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Sett A, Dahm SI, Tingay DG. Lung Ultrasound and Regional Heterogeneity: A Bedside Solution to an Underrecognized Problem? Anesthesiology 2024; 141:635-637. [PMID: 39254536 DOI: 10.1097/aln.0000000000005136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Affiliation(s)
- Arun Sett
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia; Joan Kirner Women's and Children's, Sunshine Hospital, Melbourne, Australia; Department of Obstetrics, Gynaecology and Newborn Health, University of Melbourne, Melbourne, Australia
| | - Sophia I Dahm
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia
| | - David G Tingay
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia
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2
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Hibberd J, Leontini J, Scott T, Pillow JJ, Miedema M, Rimensberger PC, Tingay DG. Neonatal high-frequency oscillatory ventilation: where are we now? Arch Dis Child Fetal Neonatal Ed 2024; 109:467-474. [PMID: 37726160 DOI: 10.1136/archdischild-2023-325657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 09/04/2023] [Indexed: 09/21/2023]
Abstract
High-frequency oscillatory ventilation (HFOV) is an established mode of respiratory support in the neonatal intensive care unit. Large clinical trial data is based on first intention use in preterm infants with acute respiratory distress syndrome. Clinical practice has evolved from this narrow population. HFOV is most often reserved for term and preterm infants with severe, and often complex, respiratory failure not responding to conventional modalities of respiratory support. Thus, optimal, and safe, application of HFOV requires the clinician to adapt mean airway pressure, frequency, inspiratory:expiratory ratio and tidal volume to individual patient needs based on pathophysiology, lung volume state and infant size. This narrative review summarises the status of HFOV in neonatal intensive care units today, the lessons that can be learnt from the past, how to apply HFOV in different neonatal populations and conditions and highlights potential new advances. Specifically, we provide guidance on how to apply an open lung approach to mean airway pressure, selecting the correct frequency and use of volume-targeted HFOV.
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Affiliation(s)
- Jakob Hibberd
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Justin Leontini
- Department of Mechanical and Product Design Engineering, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Thomas Scott
- Department of Mechanical and Product Design Engineering, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - J Jane Pillow
- School of Human Science, The University of Western Australia, Perth, Western Australia, Australia
- NCCU, King Edward Memorial Hospital Neonatal Clinical Care Unit, Subiaco, Western Australia, Australia
- Telethon Kids Institute, Perth, Western Australia, Australia
| | - Martijn Miedema
- Neonatology, Amsterdam Universitair Medische Centra, Amsterdam, The Netherlands
| | | | - David Gerald Tingay
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
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3
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Mammel MC. Evolution of mechanical ventilation of the newborn infant. Semin Perinatol 2024; 48:151884. [PMID: 38555220 DOI: 10.1016/j.semperi.2024.151884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
Artificial ventilation of the newborn infant is the foundation of neonatology. Early practitioners included pediatricians, anesthesiologists, cardiologists, respiratory therapists, and engineers. The discovery of surfactant, followed by the death of Patrick Kennedy, jump-started the new area, with investment and research rapidly expanding. The ever more complex design of mechanical ventilators necessitated a more thorough understanding of newborn pulmonary physiology in order to provide support with minimal associated injury. This piece briefly reviews and highlights this history.
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Affiliation(s)
- Mark C Mammel
- Professor of Pediatrics, University of Minnesota, Minneapolis, MN 55455, United States.
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4
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Courtney SE, van Kaam AH, Pillow JJ. Neonatal high frequency ventilation: Current trends and future directions. Semin Perinatol 2024; 48:151887. [PMID: 38556386 DOI: 10.1016/j.semperi.2024.151887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
High frequency ventilation (HFV) in neonates has been in use for over forty years. Some early HFV ventilators are no longer available, but high frequency oscillatory ventilation (HFOV) and jet ventilators (HFJV) continue to be commonly employed. Advanced HFOV models available outside of the United States are much quieter and easier to use, and are available as options on many conventional ventilators, providing important improvements such as tidal volume measurement and targeting. HFJV excels in treating air leak and non-homogenous lung disease and is often used for other diseases as well. High frequency non-invasive ventilation (hfNIV) is a novel application of HFV that remains under investigation. Similar to bubble CPAP, hfNIV has been applied with a variety of high-frequency ventilators. Efficacy and safety of hfNIV with any device have not yet been established. This article describes the current approaches to these HFV therapies and stresses the importance of understanding how each device works and what disease processes may respond best to the technology employed.
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Affiliation(s)
- Sherry E Courtney
- Department of Pediatrics, Section of Neonatology, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, One Children's Way, Little Rock, AR 72202 USA.
| | - Anton H van Kaam
- Department of Neonatology, Emma Children's Hospital, Amsterdam UMC, Amsterdam Reproduction and Development Research Institute, Amsterdam, the Netherlands
| | - J Jane Pillow
- School of Human Sciences, University of Western Australia, Telethon Kids Institute, Perth, Australia
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5
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De Luca D, Loi B, Tingay D, Fiori H, Kingma P, Dellacà R, Autilio C. Surfactant status assessment and personalized therapy for surfactant deficiency or dysfunction. Semin Fetal Neonatal Med 2023; 28:101494. [PMID: 38016825 DOI: 10.1016/j.siny.2023.101494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
Surfactant is a pivotal neonatal drug used both for respiratory distress syndrome due to surfactant deficiency and for more complex surfactant dysfunctions (such as in case of neonatal acute respiratory distress syndrome). Despite its importance, indications for surfactant therapy are often based on oversimplified criteria. Lung biology and modern monitoring provide several diagnostic tools to assess the patient surfactant status and they can be used for a personalized surfactant therapy. This is desirable to improve the efficacy of surfactant treatment and reduce associated costs and side effects. In this review we will discuss these diagnostic tools from a pathophysiological and multi-disciplinary perspective, focusing on the quantitative or qualitative surfactant assays, lung mechanics or aeration measurements, and gas exchange metrics. Their biological and technical characteristics are described with practical information for clinicians. Finally, available evidence-based data are reviewed, and the diagnostic accuracy of the different tools is compared. Lung ultrasound seems the most suitable tool for assessing the surfactant status, while some other promising tests require further research and/or development.
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Affiliation(s)
- Daniele De Luca
- Division of Pediatrics and Neonatal Critical Care, "Antoine Béclère" Hospital, Paris Saclay University Hospitals, APHP, Paris, France; Physiopathology and Therapeutic Innovation Unit, INSERM U999, Paris Saclay University, Paris, France; Department of Pediatrics, Division of Neonatology, Stanford University, School of Medicine - Lucile Packard Children's Hospital, Palo Alto, CA, USA.
| | - Barbara Loi
- Division of Pediatrics and Neonatal Critical Care, "Antoine Béclère" Hospital, Paris Saclay University Hospitals, APHP, Paris, France; Physiopathology and Therapeutic Innovation Unit, INSERM U999, Paris Saclay University, Paris, France
| | - David Tingay
- Neonatal Research Unit, Murdoch Children's Research Institute, Parkville, Australia; Department of Pediatrics, University of Melbourne, Melbourne, Australia
| | - Humberto Fiori
- Division of Neonatology, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Paul Kingma
- Perinatal Institute, Cincinnati Children's University Hospital Medical Center, Cincinnati, OH, USA
| | - Raffaele Dellacà
- Department of Electronics, Information and Bio-engineering, Polytechnical University of Milan, Milan, Italy
| | - Chiara Autilio
- Department of Biochemistry and Molecular Biology and Research Institute Hospital October 12 (imas12), Faculty of Biology, Complutense University, Madrid, Spain; Clinical Pathology and Microbiology Unit, San Carlo Hospital, Potenza, Italy
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Sahin O, Colak D, Tasar S, Yavanoglu Atay F, Guran O, Mungan Akin I. Point-of-Care Ultrasound versus Chest X-Ray for Determining Lung Expansion Based on Rib Count in High-Frequency Oscillatory Ventilation. Neonatology 2023; 120:736-740. [PMID: 37634488 DOI: 10.1159/000533318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 07/25/2023] [Indexed: 08/29/2023]
Abstract
INTRODUCTION Chest X-ray (CXR) is the most prevalent method for evaluating lung expansion in high-frequency oscillatory ventilation (HFOV). The purpose of this study was to compare the accuracy of chest radiography with point-of-care ultrasound (POCUS) in determining lung expansion. METHODS This prospective study included newborns who required HFOV and were monitored in a neonatal intensive care unit. A single neonatologist assessed lung expansion with CXR and POCUS to measure the costal level of the right hemidiaphragm and compared the results. RESULTS A neonatologist performed 55 measurements in 28 newborns with a gestational age of 32 (23.2-39.4) weeks, followed by HFOV. The rib counts obtained from anterior chest ultrasonography and posterior CXR showed a statistically high concordance (r = 0.913, p < 0.001). CONCLUSION Lung ultrasonography is a reliable method for the evaluation of lung expansion based on rib count in patients with HFOV.
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Affiliation(s)
- Ozlem Sahin
- Division of Neonatology, University of Health Sciences, Umraniye Training and Research Hospital, Istanbul, Turkey
| | - Derya Colak
- Division of Neonatology, University of Health Sciences, Umraniye Training and Research Hospital, Istanbul, Turkey
| | - Sevinc Tasar
- Department of Radiology, University of Health Sciences, Umraniye Training and Research Hospital, Istanbul, Turkey
| | - Funda Yavanoglu Atay
- Division of Neonatology, University of Health Sciences, Umraniye Training and Research Hospital, Istanbul, Turkey
| | - Omer Guran
- Division of Neonatology, University of Health Sciences, Umraniye Training and Research Hospital, Istanbul, Turkey
| | - Ilke Mungan Akin
- Division of Neonatology, University of Health Sciences, Umraniye Training and Research Hospital, Istanbul, Turkey
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Respiratory Management of the Preterm Infant: Supporting Evidence-Based Practice at the Bedside. CHILDREN 2023; 10:children10030535. [PMID: 36980093 PMCID: PMC10047523 DOI: 10.3390/children10030535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/10/2023] [Accepted: 03/08/2023] [Indexed: 03/14/2023]
Abstract
Extremely preterm infants frequently require some form of respiratory assistance to facilitate the cardiopulmonary transition that occurs in the first hours of life. Current resuscitation guidelines identify as a primary determinant of overall newborn survival the establishment, immediately after birth, of adequate lung inflation and ventilation to ensure an adequate functional residual capacity. Any respiratory support provided, however, is an important contributing factor to the development of bronchopulmonary dysplasia. The risks correlated to invasive ventilatory techniques increase inversely with gestational age. Preterm infants are born at an early stage of lung development and are more susceptible to lung injury deriving from mechanical ventilation. Any approach aiming to reduce the global burden of preterm lung disease must implement lung-protective ventilation strategies that begin from the newborn’s first breaths in the delivery room. Neonatologists today must be able to manage both invasive and noninvasive forms of respiratory assistance to treat a spectrum of lung diseases ranging from acute to chronic conditions. We searched PubMed for articles on preterm infant respiratory assistance. Our narrative review provides an evidence-based overview on the respiratory management of preterm infants, especially in the acute phase of neonatal respiratory distress syndrome, starting from the delivery room and continuing in the neonatal intensive care unit, including a section regarding exogenous surfactant therapy.
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Sett A, Kenna KR, Sutton RJ, Perkins EJ, Sourial M, Chapman JD, Donath SM, Sasi A, Rogerson SR, Manley BJ, Davis PG, Pereira-Fantini PM, Tingay DG. Lung ultrasound of the dependent lung detects real-time changes in lung volume in the preterm lamb. Arch Dis Child Fetal Neonatal Ed 2023; 108:51-56. [PMID: 35750468 PMCID: PMC9763221 DOI: 10.1136/archdischild-2022-323900] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 06/03/2022] [Indexed: 12/28/2022]
Abstract
BACKGROUND Effective lung protective ventilation requires reliable, real-time estimation of lung volume at the bedside. Neonatal clinicians lack a readily available imaging tool for this purpose. OBJECTIVE To determine the ability of lung ultrasound (LUS) of the dependent region to detect real-time changes in lung volume, identify opening and closing pressures of the lung, and detect pulmonary hysteresis. METHODS LUS was performed on preterm lambs (n=20) during in vivo mapping of the pressure-volume relationship of the respiratory system using the super-syringe method. Electrical impedance tomography was used to derive regional lung volumes. Images were blindly graded using an expanded scoring system. The scores were compared with total and regional lung volumes, and differences in LUS scores between pressure increments were calculated. RESULTS Changes in LUS scores correlated moderately with changes in total lung volume (r=0.56, 95% CI 0.47-0.64, p<0.0001) and fairly with right whole (r=0.41, CI 0.30-0.51, p<0.0001), ventral (r=0.39, CI 0.28-0.49, p<0.0001), central (r=0.41, CI 0.31-0.52, p<0.0001) and dorsal (r=0.38, CI 0.27-0.49, p<0.0001) regional lung volumes. The pressure-volume relationship of the lung exhibited hysteresis in all lambs. LUS was able to detect hysteresis in 17 (85%) lambs. The greatest changes in LUS scores occurred at the opening and closing pressures. CONCLUSION LUS was able to detect large changes in total and regional lung volume in real time and correctly identified opening and closing pressures but lacked the precision to detect small changes in lung volume. Further work is needed to improve precision prior to translation to clinical practice.
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Affiliation(s)
- Arun Sett
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia .,Newborn Research Centre, The Royal Women's Hospital, Melbourne, Victoria, Australia.,Newborn Services, Joan Kirner Women's and Children's, Sunshine Hospital, Western Health, Melbourne, Victoria, Australia.,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia.,Paediatric Infant Perinatal Emergency Retrieval, The Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Kelly R Kenna
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Rebecca J Sutton
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia,Translational Research Unit, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Magdy Sourial
- Translational Research Unit, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Jack D Chapman
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Susan M Donath
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Arun Sasi
- Paediatric Infant Perinatal Emergency Retrieval, The Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Sheryle R Rogerson
- Newborn Research Centre, The Royal Women's Hospital, Melbourne, Victoria, Australia,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia,Paediatric Infant Perinatal Emergency Retrieval, The Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Brett J Manley
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia,Newborn Research Centre, The Royal Women's Hospital, Melbourne, Victoria, Australia,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia
| | - Peter G Davis
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia,Newborn Research Centre, The Royal Women's Hospital, Melbourne, Victoria, Australia,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia
| | - Prue M Pereira-Fantini
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - David G Tingay
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia,Newborn Research Centre, The Royal Women's Hospital, Melbourne, Victoria, Australia,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia,Department of Neonatology, The Royal Children's Hospital, Melbourne, Victoria, Australia
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9
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Solis-Garcia G, González-Pacheco N, Ramos-Navarro C, Vigil-Vázquez S, Gutiérrez-Vélez A, Merino-Hernández A, Rodríguez Sánchez De la Blanca A, Sánchez-Luna M. Lung recruitment in neonatal high-frequency oscillatory ventilation with volume-guarantee. Pediatr Pulmonol 2022; 57:3000-3008. [PMID: 35996817 DOI: 10.1002/ppul.26124] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 07/13/2022] [Accepted: 08/07/2022] [Indexed: 01/11/2023]
Abstract
BACKGROUND AND OBJECTIVES The optimal lung volume strategy during high-frequency oscillatory ventilation (HFOV) is reached by performing recruitment maneuvers, usually guided by the response in oxygenation. In animal models, secondary spontaneous change in oscillation pressure amplitude (ΔPhf) associated with a progressive increase in mean airway pressure during HFOV combined with volume guarantee (HFOV-VG) identifies optimal lung recruitment. The aim of this study was to describe recruitment maneuvers in HFOV-VG and analyze whether changes in ΔPhf might be an early predictor for lung recruitment in newborn infants with severe respiratory failure. DESIGN AND METHODS The prospective observational study was done in a tertiary-level neonatology department. Changes in ΔPhf were analyzed during standardized lung recruitment after initiating early rescue HFOV-VG in preterm infants with severe respiratory failure. RESULTS Twenty-seven patients were included, with a median gestational age of 24 weeks (interquartile range [IQR]: 23-25). Recruitment maneuvers were performed, median baseline mean airway pressure (mPaw) was 11 cm H2 O (IQR: 10-13), median critical lung opening mPaw during recruitment was 14 cm H2 O (IRQ: 12-16), and median optimal mPaw was 12 cm H2 O (IQR: 10-14, p < 0.01). Recruitment maneuvers were associated with an improvement in oxygenation (FiO2 : 65.0 vs. 45.0, p < 0.01, SpO2/FiO2 ratio: 117 vs. 217, p < 0.01). ΔPhf decreased significantly after lung recruitment (mean amplitude: 23.0 vs. 16.0, p < 0.01). CONCLUSION In preterm infants with severe respiratory failure, the lung recruitment process can be effectively guided by ΔPhf on HFOV-VG.
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Affiliation(s)
- Gonzalo Solis-Garcia
- Neonatology Division, Hospital General Universitario Gregorio Marañón, Madrid, Spain.,Universidad Complutense de Madrid, Madrid, Spain.,The Hospital for Sick Children, Toronto, Canada
| | - Noelia González-Pacheco
- Neonatology Division, Hospital General Universitario Gregorio Marañón, Madrid, Spain.,Universidad Complutense de Madrid, Madrid, Spain
| | - Cristina Ramos-Navarro
- Neonatology Division, Hospital General Universitario Gregorio Marañón, Madrid, Spain.,Universidad Complutense de Madrid, Madrid, Spain
| | - Sara Vigil-Vázquez
- Neonatology Division, Hospital General Universitario Gregorio Marañón, Madrid, Spain.,Universidad Complutense de Madrid, Madrid, Spain
| | - Ana Gutiérrez-Vélez
- Neonatology Division, Hospital General Universitario Gregorio Marañón, Madrid, Spain.,Universidad Complutense de Madrid, Madrid, Spain
| | - Amaia Merino-Hernández
- Neonatology Division, Hospital General Universitario Gregorio Marañón, Madrid, Spain.,Universidad Complutense de Madrid, Madrid, Spain
| | | | - Manuel Sánchez-Luna
- Neonatology Division, Hospital General Universitario Gregorio Marañón, Madrid, Spain.,Universidad Complutense de Madrid, Madrid, Spain
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Sett A, Foo GWC, Kenna KR, Sutton RJ, Perkins EJ, Sourial M, Rogerson SR, Manley BJ, Davis PG, Pereira-Fantini PM, Tingay DG. Quantitative lung ultrasound detects dynamic changes in lung recruitment in the preterm lamb. Pediatr Res 2022; 93:1591-1598. [PMID: 36167816 PMCID: PMC10172106 DOI: 10.1038/s41390-022-02316-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/24/2022] [Accepted: 09/07/2022] [Indexed: 11/09/2022]
Abstract
BACKGROUND Lung ultrasound (LUS) may not detect small, dynamic changes in lung volume. Mean greyscale measurement using computer-assisted image analysis (Q-LUSMGV) may improve the precision of these measurements. METHODS Preterm lambs (n = 40) underwent LUS of the dependent or non-dependent lung during static pressure-volume curve mapping. Total and regional lung volumes were determined using the super-syringe technique and electrical impedance tomography. Q-LUSMGV and gold standard measurements of lung volume were compared in 520 images. RESULTS Dependent Q-LUSMGV moderately correlated with total lung volume (rho = 0.60, 95% CI 0.51-0.67) and fairly with right whole (rho = 0.39, 0.27-0.49), central (rho = 0.38, 0.27-0.48), ventral (rho = 0.41, 0.31-0.51) and dorsal regional lung volumes (rho = 0.32, 0.21-0.43). Non-dependent Q-LUSMGV moderately correlated with total lung volume (rho = 0.57, 0.48-0.65) and fairly with right whole (rho = 0.43, 0.32-0.52), central (rho = 0.46, 0.35-0.55), ventral (rho = 0.36, 0.25-0.47) and dorsal lung volumes (rho = 0.36, 0.25-0.47). All correlation coefficients were statistically significant. Distinct inflation and deflation limbs, and sonographic pulmonary hysteresis occurred in 95% of lambs. The greatest changes in Q-LUSMGV occurred at the opening and closing pressures. CONCLUSION Q-LUSMGV detected changes in total and regional lung volume and offers objective quantification of LUS images, and may improve bedside discrimination of real-time changes in lung volume. IMPACT Lung ultrasound (LUS) offers continuous, radiation-free imaging that may play a role in assessing lung recruitment but may not detect small changes in lung volume. Mean greyscale image analysis using computer-assisted quantitative LUS (Q-LUSMGV) moderately correlated with changes in total and regional lung volume. Q-LUSMGV identified opening and closing pressure and pulmonary hysteresis in 95% of lambs. Computer-assisted image analysis may enhance LUS estimation of lung recruitment at the bedside. Future research should focus on improving precision prior to clinical translation.
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Affiliation(s)
- Arun Sett
- Neonatal Research, Murdoch Children's Research Institute, Parkville, VIC, Australia. .,Newborn Research Centre, The Royal Women's Hospital, Parkville, VIC, Australia. .,Joan Kirner Women's and Children's Hospital, Western Health, St Albans, VIC, Australia. .,Department of Obstetrics and Gynaecology, The University of Melbourne, Parkville, VIC, Australia. .,Paediatric Infant Perinatal Emergency Retrieval, The Royal Children's Hospital, Parkville, VIC, Australia.
| | - Gillian W C Foo
- Newborn Research Centre, The Royal Women's Hospital, Parkville, VIC, Australia
| | - Kelly R Kenna
- Neonatal Research, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Rebecca J Sutton
- Neonatal Research, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Translational Research Unit, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Magdy Sourial
- Translational Research Unit, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Sheryle R Rogerson
- Newborn Research Centre, The Royal Women's Hospital, Parkville, VIC, Australia.,Department of Obstetrics and Gynaecology, The University of Melbourne, Parkville, VIC, Australia.,Paediatric Infant Perinatal Emergency Retrieval, The Royal Children's Hospital, Parkville, VIC, Australia
| | - Brett J Manley
- Neonatal Research, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Newborn Research Centre, The Royal Women's Hospital, Parkville, VIC, Australia.,Department of Obstetrics and Gynaecology, The University of Melbourne, Parkville, VIC, Australia
| | - Peter G Davis
- Neonatal Research, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Newborn Research Centre, The Royal Women's Hospital, Parkville, VIC, Australia.,Department of Obstetrics and Gynaecology, The University of Melbourne, Parkville, VIC, Australia
| | - Prue M Pereira-Fantini
- Neonatal Research, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Newborn Research Centre, The Royal Women's Hospital, Parkville, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia
| | - David G Tingay
- Neonatal Research, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Newborn Research Centre, The Royal Women's Hospital, Parkville, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia.,Department of Neonatology, The Royal Children's Hospital, Parkville, VIC, Australia
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11
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De Luca D, Tingay DG, van Kaam AH, Courtney SE, Kneyber MCJ, Tissieres P, Tridente A, Rimensberger PC, Pillow JJ. Epidemiology of Neonatal Acute Respiratory Distress Syndrome: Prospective, Multicenter, International Cohort Study. Pediatr Crit Care Med 2022; 23:524-534. [PMID: 35543390 DOI: 10.1097/pcc.0000000000002961] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Age-specific definitions for acute respiratory distress syndrome (ARDS) are available, including a specific definition for neonates (the "Montreux definition"). The epidemiology of neonatal ARDS is unknown. The objective of this study was to describe the epidemiology, clinical course, treatment, and outcomes of neonatal ARDS. DESIGN Prospective, international, observational, cohort study. SETTING Fifteen academic neonatal ICUs. PATIENTS Consecutive sample of neonates of any gestational age admitted to participating sites who met the neonatal ARDS Montreux definition criteria. MEASUREMENTS AND MAIN RESULTS Neonatal ARDS was classified as direct or indirect, infectious or noninfectious, and perinatal (≤ 72 hr after birth) or late in onset. Primary outcomes were: 1) survival at 30 days from diagnosis, 2) inhospital survival, and 3) extracorporeal membrane oxygenation (ECMO)-free survival at 30 days from diagnosis. Secondary outcomes included respiratory complications and common neonatal extrapulmonary morbidities. A total of 239 neonates met criteria for the diagnosis of neonatal ARDS. The median prevalence was 1.5% of neonatal ICU admissions with male/female ratio of 1.5. Respiratory treatments were similar across gestational ages. Direct neonatal ARDS (51.5% of neonates) was more common in term neonates and the perinatal period. Indirect neonatal ARDS was often triggered by an infection and was more common in preterm neonates. Thirty-day, inhospital, and 30-day ECMO-free survival were 83.3%, 76.2%, and 79.5%, respectively. Direct neonatal ARDS was associated with better survival outcomes than indirect neonatal ARDS. Direct and noninfectious neonatal ARDS were associated with the poorest respiratory outcomes at 36 and 40 weeks' postmenstrual age. Gestational age was not associated with any primary outcome on multivariate analyses. CONCLUSIONS Prevalence and survival of neonatal ARDS are similar to those of pediatric ARDS. The neonatal ARDS subtypes used in the current definition may be associated with distinct clinical outcomes and a different distribution for term and preterm neonates.
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Affiliation(s)
- Daniele De Luca
- Division of Pediatrics and Neonatal Critical Care, "A.Béclère" Medical Centre, Paris Saclay University Hospitals, APHP, Paris, France
- Physiopathology and Therapeutic Innovation Unit-INSERM U999, Paris Saclay University, Paris, France
| | - David G Tingay
- Division of Pediatrics and Neonatal Critical Care, "A.Béclère" Medical Centre, Paris Saclay University Hospitals, APHP, Paris, France
- Physiopathology and Therapeutic Innovation Unit-INSERM U999, Paris Saclay University, Paris, France
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia
- Department of Neonatology, Royal Children's Hospital, Melbourne, VIC, Australia
- Department of Pediatrics, University of Melbourne, Melbourne, VIC, Australia
- Department of Neonatology, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR
- Department of Pediatrics, Division of Pediatric Critical Care Medicine, Beatrix Children's Hospital Groningen, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
- Critical Care, Anesthesiology, Peri-operative & Emergency Medicine (CAPE), University of Groningen, Groningen, The Netherlands
- Division of Pediatric Critical Care and Neonatal Medicine, "Kremlin-Bicetre" Hospital, Paris Saclay University Hospitals, APHP, Paris, France
- Host-Pathogen Interactions Team, Integrative Cellular Biology Institute-UMR 9198, Paris Saclay University, Paris, France
- Intensive Care Unit, Whiston Hospital, "St. Helens and Knowsley" Teaching Hospitals NHS Trust, Liverpool, United Kingdom
- Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Division of Neonatology and Pediatric Critical Care, Department of Pediatrics, University Hospital of Geneva, University of Geneva, Geneva, Switzerland
- School of Human Sciences, The University of Western Australia, Perth, WA, Australia
- Wal-yan Respiratory Research Centre and Neonatal Cardiorespiratory Health, Telethon Kids Institute, Perth, WA, Australia
| | - Anton H van Kaam
- Department of Neonatology, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Sherry E Courtney
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Martin C J Kneyber
- Department of Pediatrics, Division of Pediatric Critical Care Medicine, Beatrix Children's Hospital Groningen, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
- Critical Care, Anesthesiology, Peri-operative & Emergency Medicine (CAPE), University of Groningen, Groningen, The Netherlands
| | - Pierre Tissieres
- Division of Pediatric Critical Care and Neonatal Medicine, "Kremlin-Bicetre" Hospital, Paris Saclay University Hospitals, APHP, Paris, France
- Host-Pathogen Interactions Team, Integrative Cellular Biology Institute-UMR 9198, Paris Saclay University, Paris, France
| | - Ascanio Tridente
- Intensive Care Unit, Whiston Hospital, "St. Helens and Knowsley" Teaching Hospitals NHS Trust, Liverpool, United Kingdom
- Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
| | | | - J Jane Pillow
- School of Human Sciences, The University of Western Australia, Perth, WA, Australia
- Wal-yan Respiratory Research Centre and Neonatal Cardiorespiratory Health, Telethon Kids Institute, Perth, WA, Australia
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12
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Abstract
Extremely preterm infants who must suddenly support their own gas exchange with lungs that are incompletely developed and lacking adequate amount of surfactant and antioxidant defenses are susceptible to lung injury. The decades-long quest to prevent bronchopulmonary dysplasia has had limited success, in part because of increasing survival of more immature infants. The process must begin in the delivery room with gentle assistance in establishing and maintaining adequate lung aeration, followed by noninvasive support and less invasive surfactant administration. Various modalities of invasive and noninvasive support have been used with varying degree of effect and are reviewed in this article.
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13
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High-frequency ventilation in preterm infants and neonates. Pediatr Res 2022:10.1038/s41390-021-01639-8. [PMID: 35136198 DOI: 10.1038/s41390-021-01639-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 06/20/2021] [Accepted: 06/21/2021] [Indexed: 11/08/2022]
Abstract
High-frequency ventilation (HFV) has been used as a respiratory support mode for neonates for over 30 years. HFV is characterized by delivering tidal volumes close to or less than the anatomical dead space. Both animal and clinical studies have shown that HFV can effectively restore lung function, and potentially limit ventilator-induced lung injury, which is considered an important risk factor for developing bronchopulmonary dysplasia (BPD). Knowledge of how HFV works, how it influences cardiorespiratory physiology, and how to apply it in daily clinical practice has proven to be essential for its optimal and safe use. We will present important aspects of gas exchange, lung-protective concepts, clinical use, and possible adverse effects of HFV. We also discuss the study results on the use of HFV in respiratory distress syndrome in preterm infants and respiratory failure in term neonates. IMPACT: Knowledge of how HFV works, how it influences cardiorespiratory physiology, and how to apply it in daily clinical practice has proven to be essential for its optimal and safe use. Therefore, we present important aspects of gas exchange, lung-protective concepts, clinical use, and possible adverse effects of HFV. The use of HFV in daily clinical practice in lung recruitment, determination of the optimal continuous distending pressure and frequency, and typical side effects of HFV are discussed. We also present study results on the use of HFV in respiratory distress syndrome in preterm infants and respiratory failure in term neonates.
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14
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Abstract
Mechanical ventilation can be life-saving for the premature infant, but is often injurious to immature and underdeveloped lungs. Lung injury is caused by atelectrauma, oxygen toxicity, and volutrauma. Lung protection must include appropriate lung recruitment starting in the delivery suite and throughout mechanical ventilation. Strategies include open lung ventilation, positive end-expiratory pressure, and volume-targeted ventilation. Respiratory function monitoring, such as capnography and ventilator graphics, provides clinicians with continuous real-time information and an adjunct to optimize lung-protective ventilatory strategies. Further research is needed to assess which lung-protective strategies result in a decrease in long-term respiratory morbidity.
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15
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Thomson J, Rüegger CM, Perkins EJ, Pereira-Fantini PM, Farrell O, Owen LS, Tingay DG. Regional ventilation characteristics during non-invasive respiratory support in preterm infants. Arch Dis Child Fetal Neonatal Ed 2021; 106:370-375. [PMID: 33246967 DOI: 10.1136/archdischild-2020-320449] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/14/2020] [Accepted: 11/03/2020] [Indexed: 01/04/2023]
Abstract
OBJECTIVES To determine the regional ventilation characteristics during non-invasive ventilation (NIV) in stable preterm infants. The secondary aim was to explore the relationship between indicators of ventilation homogeneity and other clinical measures of respiratory status. DESIGN Prospective observational study. SETTING Two tertiary neonatal intensive care units. PATIENTS Forty stable preterm infants born <30 weeks of gestation receiving either continuous positive airway pressure (n=32) or high-flow nasal cannulae (n=8) at least 24 hours after extubation at time of study. INTERVENTIONS Continuous electrical impedance tomography imaging of regional ventilation during 60 min of quiet breathing on clinician-determined non-invasive settings. MAIN OUTCOME MEASURES Gravity-dependent and right-left centre of ventilation (CoV), percentage of whole lung tidal volume (VT) by lung region and percentage of lung unventilated were determined for 120 artefact-free breaths/infant (4770 breaths included). Oxygen saturation, heart and respiratory rates were also measured. RESULTS Ventilation was greater in the right lung (mean 69.1 (SD 14.9)%) total VT and the gravity-non-dependent (ND) lung; ideal-actual CoV 1.4 (4.5)%. The central third of the lung received the most VT, followed by the non-dependent and dependent regions (p<0.0001 repeated-measure analysis of variance). Ventilation inhomogeneity was associated with worse peripheral capillary oxygen saturation (SpO2)/fraction of inspired oxygen (FiO2) (p=0.031, r2 0.12; linear regression). In those infants that later developed bronchopulmonary dysplasia (n=25), SpO2/FiO2 was worse and non-dependent ventilation inhomogeneity was greater than in those that did not (both p<0.05, t-test Welch correction). CONCLUSIONS There is high breath-by-breath variability in regional ventilation patterns during NIV in preterm infants. Ventilation favoured the ND lung, with ventilation inhomogeneity associated with worse oxygenation.
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Affiliation(s)
- Jessica Thomson
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia .,Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Christoph M Rüegger
- Newborn Research, The Royal Women's Hospital, Parkville, Victoria, Australia.,Newborn Research, Department of Neonatology, University Hospital and University of Zürich, Zürich, Switzerland
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | | | - Olivia Farrell
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Louise S Owen
- Newborn Research, The Royal Women's Hospital, Parkville, Victoria, Australia
| | - David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatology, The Royal Children's Hospital Melbourne, Parkville, Victoria, Australia
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16
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Abstract
Supplemental Digital Content is available in the text. OBJECTIVES: Clinicians have little guidance on the time needed before assessing the effect of a mean airway pressure change during high-frequency oscillatory ventilation. We aimed to determine: 1) time to stable lung volume after a mean airway pressure change during high-frequency oscillatory ventilation and 2) the relationship between time to volume stability and the volume state of the lung. DESIGN: Prospective observational study. SETTING: Regional quaternary teaching hospital neonatal ICU. PATIENTS: Thirteen term or near-term infants receiving high-frequency oscillatory ventilation and muscle relaxants. INTERVENTIONS: One to two cm H2O mean airway pressure changes every 10 minutes as part of an open lung strategy based on oxygen response. MEASUREMENTS AND MAIN RESULTS: Continuous lung volume measurements (respiratory inductive plethysmography) were made during the mean airway pressure changes. Volume signals were analyzed with a biexponential model to calculate the time to stable lung volume if the model R2 was greater than 0.6. If volume stability did not occur within 10 minutes, the model was extrapolated to maximum 3,600 s. One-hundred ninety-six mean airway pressure changes were made, with no volume change in 33 occurrences (17%). One-hundred twenty-five volume signals met modeling criteria for inclusion; median (interquartile range) R2, 0.96 (0.91–0.98). The time to stable lung volume was 1,131 seconds (718–1,959 s) (mean airway pressure increases) and 647 seconds (439–1,309 s) (mean airway pressure decreases), with only 17 (14%) occurring within 10 minutes and time to stability being longer when the lung was atelectatic. CONCLUSIONS: During high-frequency oscillatory ventilation, the time to stable lung volume after a mean airway pressure change is variable, often requires more than 10 minutes, and is dependent on the preceding volume state.
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17
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Tingay DG, Farrell O, Thomson J, Perkins EJ, Pereira-Fantini PM, Waldmann AD, Rüegger C, Adler A, Davis PG, Frerichs I. Imaging the Respiratory Transition at Birth: Unraveling the Complexities of the First Breaths of Life. Am J Respir Crit Care Med 2021; 204:82-91. [PMID: 33545023 DOI: 10.1164/rccm.202007-2997oc] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Rationale: The transition to air breathing at birth is a seminal respiratory event common to all humans, but the intrathoracic processes remain poorly understood. Objectives: The objectives of this prospective, observational study were to describe the spatiotemporal gas flow, aeration, and ventilation patterns within the lung in term neonates undergoing successful respiratory transition. Methods: Electrical impedance tomography was used to image intrathoracic volume patterns for every breath until 6 minutes from birth in neonates born by elective cesearean section and not needing resuscitation. Breaths were classified by video data, and measures of lung aeration, tidal flow conditions, and intrathoracic volume distribution calculated for each inflation. Measurements and Main Results: A total of 1,401 breaths from 17 neonates met all eligibility and data analysis criteria. Stable FRC was obtained by median (interquartile range) 43 (21-77) breaths. Breathing patterns changed from predominantly crying (80.9% first min) to tidal breathing (65.3% sixth min). From birth, tidal ventilation was not uniform within the lung, favoring the right and nondependent regions; P < 0.001 versus left and dependent regions (mixed-effects model). Initial crying created a unique volumetric pattern with delayed midexpiratory gas flow associated with intrathoracic volume redistribution (pendelluft flow) within the lung. This preserved FRC, especially within the dorsal and right regions. Conclusions: The commencement of air breathing at birth generates unique flow and volume states associated with marked spatiotemporal ventilation inhomogeneity not seen elsewhere in respiratory physiology. At birth, neonates innately brake expiratory flow to defend FRC gains and redistribute gas to less aerated regions.
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Affiliation(s)
- David G Tingay
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Neonatology, Royal Children's Hospital, Melbourne, Australia.,Neonatal Research, The Royal Women's Hospital, Melbourne, Australia
| | - Olivia Farrell
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Jessica Thomson
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia
| | - Prue M Pereira-Fantini
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Andreas D Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Germany
| | | | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada; and
| | - Peter G Davis
- Neonatal Research, The Royal Women's Hospital, Melbourne, Australia
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
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18
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Rodríguez Sánchez de la Blanca A, Sánchez Luna M, González Pacheco N, Ramos Navarro C, Santos González M, Tendillo Cortijo F. New indicators for optimal lung recruitment during high frequency oscillator ventilation. Pediatr Pulmonol 2020; 55:3525-3531. [PMID: 32965770 DOI: 10.1002/ppul.25084] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 08/26/2020] [Accepted: 09/15/2020] [Indexed: 11/09/2022]
Abstract
UNLABELLED Previous research has demonstrated the potential benefit derived from the combination of high frequency oscillatory ventilation and volume guarantee mode (HFOV-VG), a procedure that allows us to explore and control very low tidal volumes. We hypothesized that secondary spontaneous change in oscillation pressure amplitude (∆Phf), while increasing the mean airway pressure (MAP) using HFOV-VG can target the lung recruitment. METHODS A two-step animal distress model study was designed; in the first-step (ex vivo model), the animal's lungs were isolated to visually check lung recruitment and, in the second one (in vivo model), they were checked through arterial oxygen partial pressure improvement. Baseline measurements were performed, ventilation was set for 10 min and followed by bronchoalveolar lavage with isotonic saline to induce depletion of surfactant and thereby achieve a low compliance lung model. The high-frequency tidal volume and frequency remained constant and the MAP was increased by 2 cmH2 O (ex vivo) and 3 cmH2 O steps (in vivo) every 2 min. Changes in ΔPhf to achieve the fixed volume were recorded at the end of each interval to describe the maximum drop point as the recruitment point. RESULTS Fourteen Wistar Han rats were included, seven on each sub-study described. After gradual MAP increments, a progressive decrease in ΔPhf related to recruited lung regions was visually demonstrated. In the in vivo model we detected a significant comparative decrease of ΔPhf, when measured against the previous value, after reaching a MAP of 11 cmH2 O up to 17 cmH2 O, correlating with a significant improvement in oxygenation. CONCLUSION The changes in ∆Phf, linked to a progressive increase in MAP during HFOV-VG, might identify optimal lung recruitment and could potentially be used as an additional lung recruitment marker.
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Affiliation(s)
| | - Manuel Sánchez Luna
- Division of Neonatology, Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | | | | | - Martín Santos González
- Medical and Surgical Research Unit, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain
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19
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Tingay DG, Pereira-Fantini PM, Oakley R, McCall KE, Perkins EJ, Miedema M, Sourial M, Thomson J, Waldmann A, Dellaca RL, Davis PG, Dargaville PA. Gradual Aeration at Birth Is More Lung Protective Than a Sustained Inflation in Preterm Lambs. Am J Respir Crit Care Med 2020; 200:608-616. [PMID: 30730759 DOI: 10.1164/rccm.201807-1397oc] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Rationale: The preterm lung is susceptible to injury during transition to air breathing at birth. It remains unclear whether rapid or gradual lung aeration at birth causes less lung injury.Objectives: To examine the effect of gradual and rapid aeration at birth on: 1) the spatiotemporal volume conditions of the lung; and 2) resultant regional lung injury.Methods: Preterm lambs (125 ± 1 d gestation) were randomized at birth to receive: 1) tidal ventilation without an intentional recruitment (no-recruitment maneuver [No-RM]; n = 19); 2) sustained inflation (SI) until full aeration (n = 26); or 3) tidal ventilation with an initial escalating/de-escalating (dynamic) positive end-expiratory pressure (DynPEEP; n = 26). Ventilation thereafter continued for 90 minutes at standardized settings, including PEEP of 8 cm H2O. Lung mechanics and regional aeration and ventilation (electrical impedance tomography) were measured throughout and correlated with histological and gene markers of early lung injury.Measurements and Main Results: DynPEEP significantly improved dynamic compliance (P < 0.0001). An SI, but not DynPEEP or No-RM, resulted in preferential nondependent lung aeration that became less uniform with time (P = 0.0006). The nondependent lung was preferential ventilated by 5 minutes in all groups, with ventilation only becoming uniform with time in the No-RM and DynPEEP groups. All strategies generated similar nondependent lung injury patterns. Only an SI caused greater upregulation of dependent lung gene markers compared with unventilated fetal controls (P < 0.05).Conclusions: Rapidly aerating the preterm lung at birth creates heterogeneous volume states, producing distinct regional injury patterns that affect subsequent tidal ventilation. Gradual aeration with tidal ventilation and PEEP produced the least lung injury.
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Affiliation(s)
- David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatology, The Royal Children's Hospital, Parkville, Victoria, Australia.,Neonatal Research, The Royal Women's Hospital, Parkville, Victoria, Australia.,Department of Paediatrics and
| | - Prue M Pereira-Fantini
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Department of Paediatrics and
| | - Regina Oakley
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Karen E McCall
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatology, The Royal Children's Hospital, Parkville, Victoria, Australia
| | - Martijn Miedema
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatology, Amsterdam University Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
| | - Magdy Sourial
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Jessica Thomson
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | | | - Raffaele L Dellaca
- Dipartimento di Elettronica, Informazione e Ingegneria Biomedica, Politecnico di Milano University, Milan, Italy
| | - Peter G Davis
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatal Research, The Royal Women's Hospital, Parkville, Victoria, Australia.,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia
| | - Peter A Dargaville
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatal and Paediatric Intensive Care Unit, Royal Hobart Hospital, Hobart, Tasmania, Australia; and.,Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
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20
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Hooper SB, Te Pas AB, Polglase GR, Wyckoff M. Animal models in neonatal resuscitation research: What can they teach us? Semin Fetal Neonatal Med 2018; 23:300-305. [PMID: 30001819 DOI: 10.1016/j.siny.2018.07.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Animal models have made and continue to make important contributions to neonatal medicine. For example, studies in fetal sheep have taught us much about the physiology of the fetal-to-neonatal transition. However, whereas animal models allow multiple factors to be investigated in a logical and systematic manner, no animal model is perfect for humans and so we need to understand the fundamental differences in physiology between the species in question and humans. Although most physiological systems are well conserved between species, some small differences exist and so wherever possible the knowledge generated from preclinical studies in animals should be tested in clinical trials. However, with the rise of evidence-based medicine the distinction between scientific knowledge generation and evidence gathering has been confused and the two have been lumped together. This misunderstands the contribution that scientific knowledge can provide. Science should be used to guide the gathering of evidence by informing the design of clinical trials, thereby increasing their likelihood of success. While scientific knowledge is not evidence, in the absence of evidence it is likely to be the best option for guiding clinical practice.
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Affiliation(s)
- Stuart B Hooper
- The Ritchie Centre, Hudson Institute for Medical Research, Melbourne, Australia; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia.
| | - Arjan B Te Pas
- Division of Neonatology, Department of Paediatrics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Graeme R Polglase
- The Ritchie Centre, Hudson Institute for Medical Research, Melbourne, Australia; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
| | - Myra Wyckoff
- Department of Pediatrics, Neonatal and Perinatal Medicine, University of Texas, South Western Medical Center, Dallas, TX, USA
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21
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Abstract
Chronic respiratory morbidity is a common complication of premature birth, generally defined by the presence of bronchopulmonary dysplasia, both clinically and in trials of respiratory therapies. However, recent data have highlighted that bronchopulmonary dysplasia does not correlate with chronic respiratory morbidity in older children born preterm. Longitudinally evaluating pulmonary morbidity from early life through to childhood provides a more rational method of defining the continuum of chronic respiratory morbidity of prematurity, and offers new insights into the efficacy of neonatal respiratory interventions. The changing nature of preterm lung disease suggests that a multimodal approach using dynamic lung function assessment will be needed to assess the efficacy of a neonatal respiratory therapy and predict the long-term respiratory consequences of premature birth. Our aim is to review the literature regarding the long-term respiratory outcomes of neonatal respiratory strategies, the difficulties of assessing dynamic lung function in infants, and potential new solutions. Better measures are needed to predict chronic respiratory morbidity in survivors born prematurely http://ow.ly/1L3n30ihq9C
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22
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Miedema M, McCall KE, Perkins EJ, Oakley RB, Pereira-Fantini PM, Rajapaksa AE, Waldmann AD, Tingay DG, van Kaam AH. Lung Recruitment Strategies During High Frequency Oscillatory Ventilation in Preterm Lambs. Front Pediatr 2018; 6:436. [PMID: 30723711 PMCID: PMC6349831 DOI: 10.3389/fped.2018.00436] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 12/31/2018] [Indexed: 01/28/2023] Open
Abstract
Background: High frequency oscillatory ventilation (HFOV) is considered a lung protective ventilation mode in preterm infants only if lung volume is optimized. However, whilst a "high lung volume strategy" is advocated for HFOV in preterm infants this strategy is not precisely defined. It is not known to what extent lung recruitment should be pursued to provide lung protection. In this study we aimed to determine the relationship between the magnitude of lung volume optimization and its effect on gas exchange and lung injury in preterm lambs. Methods: 36 surfactant-deficient 124-127 d lambs commenced HFOV immediately following a sustained inflation at birth and were allocated to either (1) no recruitment (low lung volume; LLV), (2) medium- (MLV), or (3) high lung volume (HLV) recruitment strategy. Gas exchange and lung volume changes over time were measured. Lung injury was analyzed by post mortem pressure-volume curves, alveolar protein leakage, gene expression, and histological injury score. Results: More animals in the LLV developed a pneumothorax compared to both recruitment groups. Gas exchange was superior in both recruitment groups compared to LLV. Total lung capacity tended to be lower in the LLV group. Other parameters of lung injury were not different. Conclusions: Lung recruitment during HFOV optimizes gas exchange but has only modest effects on lung injury in a preterm animal model. In the HLV group aiming at a more extensive lung recruitment gas exchange was better without affecting lung injury.
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Affiliation(s)
- Martijn Miedema
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia.,Department of Neonatology, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Karen E McCall
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia.,School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Regina B Oakley
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | | | - Anushi E Rajapaksa
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia.,Department of Neonatology, Royal Children's Hospital, Melbourne, VIC, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | | | - David G Tingay
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, VIC, Australia.,Department of Neonatology, Royal Children's Hospital, Melbourne, VIC, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Anton H van Kaam
- Department of Neonatology, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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23
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McCall KE, Waldmann AD, Pereira-Fantini P, Oakley R, Miedema M, Perkins EJ, Davis PG, Dargaville PA, Böhm SH, Dellacà R, Sourial M, Zannin E, Rajapaksa AE, Tan A, Adler A, Frerichs I, Tingay DG. Time to lung aeration during a sustained inflation at birth is influenced by gestation in lambs. Pediatr Res 2017; 82:712-720. [PMID: 28604757 DOI: 10.1038/pr.2017.141] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/20/2017] [Indexed: 11/10/2022]
Abstract
BackgroundCurrent sustained lung inflation (SI) approaches use uniform pressures and durations. We hypothesized that gestational-age-related mechanical and developmental differences would affect the time required to achieve optimal lung aeration, and resultant lung volumes, during SI delivery at birth in lambs.Methods49 lambs, in five cohorts between 118 and 139 days of gestation (term 142 d), received a standardized 40 cmH2O SI, which was delivered until 10 s after lung volume stability (optimal aeration) was visualized on real-time electrical impedance tomography (EIT), or to a maximum duration of 180 s. Time to stable lung aeration (Tstable) within the whole lung, gravity-dependent, and non-gravity-dependent regions, was determined from EIT recordings.ResultsTstable was inversely related to gestation (P<0.0001, Kruskal-Wallis test), with the median (range) being 229 (85,306) s and 72 (50,162) s in the 118-d and 139-d cohorts, respectively. Lung volume at Tstable increased with gestation from a mean (SD) of 20 (17) ml/kg at 118 d to 56 (13) ml/kg at 139 d (P=0.002, one-way ANOVA). There were no gravity-dependent regional differences in Tstable or aeration.ConclusionsThe trajectory of aeration during an SI at birth is influenced by gestational age in lambs. An understanding of this may assist in developing SI protocols that optimize lung aeration for all infants.
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Affiliation(s)
- Karen E McCall
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | | | - Prue Pereira-Fantini
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Regina Oakley
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Martijn Miedema
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Peter G Davis
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatal Research, The Royal Women's Hospital, Parkville, Victoria, Australia.,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia
| | - Peter A Dargaville
- Department of Paediatrics, Royal Hobart Hospital, Hobart, Tasmania, Australia.,Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
| | | | - Raffaele Dellacà
- TBM Lab, Dipartimento di Elettronica, Informazione e Ingegneria Biomedica-DEIB, Politecnico di Milano University, Milano, Italy
| | - Magdy Sourial
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Emanuela Zannin
- TBM Lab, Dipartimento di Elettronica, Informazione e Ingegneria Biomedica-DEIB, Politecnico di Milano University, Milano, Italy
| | - Anushi E Rajapaksa
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Andre Tan
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatal Research, The Royal Women's Hospital, Parkville, Victoria, Australia.,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia.,Department of Neonatology, The Royal Children's Hospital, Parkville, Victoria, Australia
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Bhatia R, Davis PG, Tingay DG. Regional Volume Characteristics of the Preterm Infant Receiving First Intention Continuous Positive Airway Pressure. J Pediatr 2017; 187:80-88.e2. [PMID: 28545875 DOI: 10.1016/j.jpeds.2017.04.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/27/2017] [Accepted: 04/21/2017] [Indexed: 01/19/2023]
Abstract
OBJECTIVE To determine whether applying nasal continuous positive airway pressure (CPAP) using systematic changes in continuous distending pressure (CDP) results in a quasi-static pressure-volume relationship in very preterm infants receiving first intention CPAP in the first 12-18 hours of life. STUDY DESIGN Twenty infants at <32 weeks' gestation with mild respiratory distress syndrome (RDS) managed exclusively with nasal CPAP had CDP increased from 5 to 8 to 10 cmH2O, and then decreased to 8 cmH2O and returned to baseline CDP. Each CDP was maintained for 20 min. At each CDP, relative impedance change in end-expiratory thoracic volume (ΔZEEV) and tidal volume (ΔZVT) were measured using electrical impedance tomography. Esophageal pressure (Poes) was measured as a proxy for intrapleural pressure to determine transpulmonary pressure (Ptp). RESULTS Overall, there was a relationship between Ptp and global ΔZEEV representing the pressure-volume relationship in the lungs. There were regional variations in ΔZEEV, with 13 infants exhibiting hysteresis with the greatest gains in EEV and tidal volume in the dependent lung with no hemodynamic compromise. Seven infants did not demonstrate hysteresis during decremental CDP changes. CONCLUSION It was possible to define a pressure-volume relationship of the lung and demonstrate reversal of atelectasis by systematically manipulating CDP in most very preterm infants with mild RDS. This suggests that CDP manipulation can be used to optimize the volume state of the preterm lung.
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Affiliation(s)
- Risha Bhatia
- Newborn Research, The Royal Women's Hospital, Melbourne, Australia; Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia; The University of Melbourne, Melbourne, Australia; Monash Newborn, Monash Children's Hospital, Melbourne, Australia.
| | - Peter G Davis
- Newborn Research, The Royal Women's Hospital, Melbourne, Australia; Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia; The University of Melbourne, Melbourne, Australia
| | - David G Tingay
- Newborn Research, The Royal Women's Hospital, Melbourne, Australia; Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia; The University of Melbourne, Melbourne, Australia; Department of Neonatology, The Royal Children's Hospital, Melbourne, Australia
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25
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Abouzeid T, Perkins EJ, Pereira-Fantini PM, Rajapaksa A, Suka A, Tingay DG. Tidal Volume Delivery during the Anesthetic Management of Neonates Is Variable. J Pediatr 2017; 184:51-56.e3. [PMID: 28410092 DOI: 10.1016/j.jpeds.2017.01.074] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 01/03/2017] [Accepted: 01/31/2017] [Indexed: 11/24/2022]
Abstract
OBJECTIVES To describe expiratory tidal volume (VT) during routine anesthetic management of neonates at a single tertiary neonatal surgical center, as well as the proportion of VT values within the range of 4.0-8.0 mL/kg. STUDY DESIGN A total of 26 neonates needing surgery under general anesthesia were studied, of whom 18 were intubated postoperatively. VT was measured continuously during normal clinical care using a dedicated neonatal respiratory function monitor (RFM), with clinicians blinded to values. VT, pressure, and cardiorespiratory variables were recorded regularly while intubated intraoperatively, during postoperative transport, and for 15 minutes after returning to the neonatal intensive care unit (NICU). In addition, paired VT values from the anesthetic machine were documented intraoperatively. RESULTS A total of 2597 VT measures were recorded from 26 neonates. Intraoperative and postoperative transport expiratory VT values were highly variable compared with the NICU VT (P < .0001, Kruskal-Wallis test), with 51% of inflations outside the 4.0-8.0 mL/kg range (35% and 38% of VT >8.0 mL/kg, respectively), compared with 29% in the NICU (P < .001, χ2 test). The use of a flow-inflating bag resulted in a median (range) VT of 8.5 mL/kg (range, 5.3-11.4 mL/kg) vs 5.6 ml/kg (range, 4.3-7.9 mL/kg) using a Neopuff T-piece system (P < .0001, Mann-Whitney U test). The mean anesthetic machine expiratory VT was 3.2 mL/kg (95% CI, -4.5 to 10.8 mL/kg) above RFM. CONCLUSIONS VT is highly variable during the anesthetic care of neonates, and potentially injurious VT is frequently delivered; thus, we suggest close VT monitoring using a dedicated neonatal RFM.
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Affiliation(s)
- Thanaa Abouzeid
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia; Department of Pediatrics, University of Melbourne, Melbourne, Australia
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
| | | | - Anushi Rajapaksa
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia; Department of Pediatrics, University of Melbourne, Melbourne, Australia
| | - Asha Suka
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia; Department of Pediatrics, University of Melbourne, Melbourne, Australia
| | - David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia; Department of Pediatrics, University of Melbourne, Melbourne, Australia; Neonatology, The Royal Children's Hospital, Parkville, Australia.
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26
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Zannin E, Doni D, Ventura ML, Fedeli T, Rigotti C, Dellacá RL, Tagliabue PE. Relationship between Mean Airways Pressure, Lung Mechanics, and Right Ventricular Output during High-Frequency Oscillatory Ventilation in Infants. J Pediatr 2017; 180:110-115. [PMID: 27745747 DOI: 10.1016/j.jpeds.2016.09.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 07/28/2016] [Accepted: 09/08/2016] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To characterize changes in lung mechanics and right ventricular output (RVO) during incremental/decremental continuous distending pressure (CDP) maneuvers in newborn infants receiving high-frequency oscillatory ventilation, with the aim of evaluating when open lung maneuvers are needed and whether they are beneficial. STUDY DESIGN Thirteen infants on high-frequency oscillatory ventilation were studied with a median (IQR) gestational age of 261 (253-291) weeks and median (IQR) body weight of 810 (600-1020) g. CDP was increased stepwise from 8 cmH2O to a maximum pressure and subsequently decreased until oxygenation deteriorated or a CDP of 8 cmH2O was reached. The lowest CDP that maintained good oxygenation was considered the clinically optimal CDP. At each CDP, the following variables were evaluated: oxygenation, respiratory system reactance (Xrs), and RVO by Doppler echocardiography. RESULTS At maximal CDP reached during the trial, 19 [1] cmH2O (mean [SEM]), oxygenation markedly improved, and Xrs and RVO decreased. During deflation, oxygenation remained stable over a wide range of CDP settings, Xrs returned to the baseline values, and RVO increased but the baseline values were not readily restored in all patients. CONCLUSION These results suggest that Xrs and RVO are more sensitive than oxygenation to overdistension and they may be useful in clinical practice to guide open lung maneuvers.
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Affiliation(s)
- Emanuela Zannin
- Department of Electronics, Informatics and Bioengineering, Politecnico di Milano University, Milan, Italy
| | - Daniela Doni
- Neonatal Intensive Care Unit, Fondazione MBBM, Monza, Italy
| | | | - Tiziana Fedeli
- Neonatal Intensive Care Unit, Fondazione MBBM, Monza, Italy
| | | | - Raffaele L Dellacá
- Department of Electronics, Informatics and Bioengineering, Politecnico di Milano University, Milan, Italy
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Tingay DG, Rajapaksa A, Zannin E, Pereira-Fantini PM, Dellaca RL, Perkins EJ, Zonneveld CEE, Adler A, Black D, Frerichs I, Lavizzari A, Sourial M, Grychtol B, Mosca F, Davis PG. Effectiveness of individualized lung recruitment strategies at birth: an experimental study in preterm lambs. Am J Physiol Lung Cell Mol Physiol 2016; 312:L32-L41. [PMID: 27881405 DOI: 10.1152/ajplung.00416.2016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 11/20/2016] [Indexed: 02/02/2023] Open
Abstract
Respiratory transition at birth involves rapidly clearing fetal lung liquid and preventing efflux back into the lung while aeration is established. We have developed a sustained inflation (SIOPT) individualized to volume response and a dynamic tidal positive end-expiratory pressure (PEEP) (open lung volume, OLV) strategy that both enhance this process. We aimed to compare the effect of each with a group managed with PEEP of 8 cmH2O and no recruitment maneuver (No-RM), on gas exchange, lung mechanics, spatiotemporal aeration, and lung injury in 127 ± 1 day preterm lambs. Forty-eight fetal-instrumented lambs exposed to antenatal steroids were ventilated for 60 min after application of the allocated strategy. Spatiotemporal aeration and lung mechanics were measured with electrical impedance tomography and forced-oscillation, respectively. At study completion, molecular and histological markers of lung injury were analyzed. Mean (SD) aeration at the end of the SIOPT and OLV groups was 32 (22) and 38 (15) ml/kg, compared with 17 (10) ml/kg (180 s) in the No-RM (P = 0.024, 1-way ANOVA). This translated into better oxygenation at 60 min (P = 0.047; 2-way ANOVA) resulting from better distal lung tissue aeration in SIOPT and OLV. There was no difference in lung injury. Neither SIOPT nor OLV achieved homogeneous aeration. Histological injury and mRNA biomarker upregulation were more likely in the regions with better initial aeration, suggesting volutrauma. Tidal ventilation or an SI achieves similar aeration if optimized, suggesting that preventing fluid efflux after lung liquid clearance is at least as important as fluid clearance during the initial inflation at birth.
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Affiliation(s)
- David G Tingay
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia; .,Neonatology, The Royal Children's Hospital, Parkville, Australia.,Neonatal Research, The Royal Women's Hospital, Parkville, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Anushi Rajapaksa
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Emanuela Zannin
- TBM Laboratory, Dipartimento di Elettronica, Informazione e Ingegneria Biomedica-DEIB, Politecnico di Milano University, Milano, Italy
| | - Prue M Pereira-Fantini
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Raffaele L Dellaca
- TBM Laboratory, Dipartimento di Elettronica, Informazione e Ingegneria Biomedica-DEIB, Politecnico di Milano University, Milano, Italy
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia.,Neonatology, The Royal Children's Hospital, Parkville, Australia
| | | | - Andy Adler
- Systems and Computer Engineering, Carleton University, Ottawa, Canada
| | - Don Black
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Anna Lavizzari
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia.,NICU, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico-Università degli Studi di Milano, Milano, Italy
| | - Magdy Sourial
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia
| | - Bartłomiej Grychtol
- Fraunhofer Project Group for Automation in Medicine and Biotechnology, Mannheim, Germany; and
| | - Fabio Mosca
- NICU, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico-Università degli Studi di Milano, Milano, Italy
| | - Peter G Davis
- Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia.,Neonatal Research, The Royal Women's Hospital, Parkville, Australia.,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Australia
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An Official American Thoracic Society/European Respiratory Society Workshop Report: Evaluation of Respiratory Mechanics and Function in the Pediatric and Neonatal Intensive Care Units. Ann Am Thorac Soc 2016; 13:S1-11. [PMID: 26848609 DOI: 10.1513/annalsats.201511-730st] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ready access to physiologic measures, including respiratory mechanics, lung volumes, and ventilation/perfusion inhomogeneity, could optimize the clinical management of the critically ill pediatric or neonatal patient and minimize lung injury. There are many techniques for measuring respiratory function in infants and children but very limited information on the technical ease and applicability of these tests in the pediatric and neonatal intensive care unit (PICU, NICU) environments. This report summarizes the proceedings of a 2011 American Thoracic Society Workshop critically reviewing techniques available for ventilated and spontaneously breathing infants and children in the ICU. It outlines for each test how readily it is performed at the bedside and how it may impact patient management as well as indicating future areas of potential research collaboration. From expert panel discussions and literature reviews, we conclude that many of the techniques can aid in optimizing respiratory support in the PICU and NICU, quantifying the effect of therapeutic interventions, and guiding ventilator weaning and extubation. Most techniques now have commercially available equipment for the PICU and NICU, and many can generate continuous data points to help with ventilator weaning and other interventions. Technical and validation studies in the PICU and NICU are published for the majority of techniques; some have been used as outcome measures in clinical trials, but few have been assessed specifically for their ability to improve clinical outcomes. Although they show considerable promise, these techniques still require further study in the PICU and NICU together with increased availability of commercial equipment before wider incorporation into daily clinical practice.
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Milesi I, Tingay DG, Zannin E, Bianco F, Tagliabue P, Mosca F, Lavizzari A, Ventura ML, Zonneveld CE, Perkins EJ, Black D, Sourial M, Dellacá RL. Intratracheal atomized surfactant provides similar outcomes as bolus surfactant in preterm lambs with respiratory distress syndrome. Pediatr Res 2016; 80:92-100. [PMID: 26954481 DOI: 10.1038/pr.2016.39] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/21/2015] [Indexed: 11/09/2022]
Abstract
BACKGROUND Aerosolization of exogenous surfactant remains a challenge. This study is aimed to evaluate the efficacy of atomized poractant alfa (Curosurf) administered with a novel atomizer in preterm lambs with respiratory distress syndrome. METHODS Twenty anaesthetized lambs, 127 ± 1 d gestational age, (mean ± SD) were instrumented before birth and randomized to receive either (i) positive pressure ventilation without surfactant (Control group), (ii) 200 mg/kg of bolus instilled surfactant (Bolus group) at 10 min of life or (iii) 200 mg/kg of atomized surfactant (Atomizer group) over 60 min from 10 min of life. All lambs were ventilated for 180 min with a standardized protocol. Lung mechanics, regional lung compliance (electrical impedance tomography), and carotid blood flow (CBF) were measured with arterial blood gas analysis. RESULTS Dynamic compliance and oxygenation responses were similar in the Bolus and Atomizer groups, and both better than Control by 180 min (all P < 0.05; two-way ANOVA). Both surfactant groups demonstrated more homogeneous regional lung compliance throughout the study period. There were no differences in CBFConclusion:In a preterm lamb model, atomized surfactant resulted in similar gas exchange and mechanics as bolus administration. This study suggests evaluation of supraglottic atomization with this system when noninvasive support is warranted.
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Affiliation(s)
- Ilaria Milesi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano University, Milano, Italy
| | - David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia.,Neonatology, The Royal Children's Hospital, Parkville, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Emanuela Zannin
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano University, Milano, Italy
| | - Federico Bianco
- Research and Development Department, Chiesi Farmaceutici SpA, Parma, Italy
| | | | - Fabio Mosca
- NICU, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico-Università degli Studi di Milano
| | - Anna Lavizzari
- NICU, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico-Università degli Studi di Milano
| | | | - C Elroy Zonneveld
- Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia
| | - Don Black
- Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia
| | - Magdy Sourial
- Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia
| | - Raffaele L Dellacá
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano University, Milano, Italy
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Tingay DG, Rajapaksa A, McCall K, Zonneveld CEE, Black D, Perkins E, Sourial M, Lavizzari A, Davis PG. The interrelationship of recruitment maneuver at birth, antenatal steroids, and exogenous surfactant on compliance and oxygenation in preterm lambs. Pediatr Res 2016; 79:916-21. [PMID: 26866905 DOI: 10.1038/pr.2016.25] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 12/07/2015] [Indexed: 12/22/2022]
Abstract
BACKGROUND To describe the interrelationship between antenatal steroids, exogenous surfactant, and two approaches to lung recruitment at birth on oxygenation and respiratory system compliance (Cdyn) in preterm lambs. METHODS Lambs (n = 63; gestational age 127 ± 1 d) received either surfactant at 10-min life (Surfactant), antenatal corticosteroids (Steroid), or neither (Control). Within each epoch lambs were randomly assigned to a 30-s 40 cmH2O sustained inflation (SI) or an initial stepwise positive end-expiratory pressure (PEEP) open lung ventilation (OLV) maneuver at birth. All lambs then received the same management for 60-min with alveolar-arterial oxygen difference (AaDO2) and Cdyn measured at regular time points. RESULTS Overall, the OLV strategy improved Cdyn and AaDO2 (all epochs except Surfactant) compared to SI (all P < 0.05; two-way ANOVA). Irrespective of strategy, Cdyn was better in the Steroid group in the first 10 min (all P < 0.05). Thereafter, Cdyn was similar to Steroid epoch in the OLV + Surfactant, but not SI + Surfactant group. OLV influenced the effect of steroid and surfactant (P = 0.005) on AaDO2 more than SI (P = 0.235). CONCLUSIONS The antenatal state of the lung influences the type and impact of a recruitment maneuver at birth. The effectiveness of surfactant maybe enhanced using PEEP-based time-dependent recruitment strategies rather than approaches solely aimed at initial lung liquid clearance.
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Affiliation(s)
- David G Tingay
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia.,Department of Neonatology, The Royal Children's Hospital, Melbourne, Victoria, Australia.,Neonatal Research Group, The Royal Women's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Anushi Rajapaksa
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Karen McCall
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Cornelis E E Zonneveld
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Don Black
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Elizabeth Perkins
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Magdy Sourial
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia.,Department of Neonatology, The Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Anna Lavizzari
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia.,NICU, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico-Università degli Studi di Milano, Milano, Italy
| | - Peter G Davis
- Neonatal Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia.,Neonatal Research Group, The Royal Women's Hospital, Melbourne, Victoria, Australia.,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia
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Samransamruajkit R, Rassameehirun C, Pongsanon K, Huntrakul S, Deerojanawong J, Sritippayawan S, Prapphal N. A comparison of clinical efficacy between high frequency oscillatory ventilation and conventional ventilation with lung volume recruitment in pediatric acute respiratory distress syndrome: A randomized controlled trial. Indian J Crit Care Med 2016; 20:72-7. [PMID: 27076706 PMCID: PMC4810936 DOI: 10.4103/0972-5229.175940] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
PURPOSE To determine the efficacy of lung volume recruitment maneuver (LVRM) with high frequency oscillatory ventilation (HFOV) on oxygenation, hemodynamic alteration, and clinical outcomes when compared to conventional mechanical ventilation (CV) in children with severe acute respiratory distress syndrome (ARDS). MATERIALS We performed a randomized controlled trial and enrolled pediatric patients who were diagnosed to have severe ARDS upon pediatric intensive care unit (PICU) admission. LVRM protocol combined with HFOV or conventional mechanical ventilation was used. Baseline characteristic data, oxygenation, hemodynamic parameters, and clinical outcomes were recorded. RESULTS Eighteen children with severe ARDS were enrolled in our study. The primary cause of ARDS was pneumonia (91.7%). Their mean age was 47.7 ± 61.2 (m) and body weight was 25.3 ± 27.1 (kg). Their initial pediatric risk of mortality score 3 and pediatric logistic organ dysfunction were 12 ± 9.2 and 15.9 ± 12.8, respectively. The initial mean oxygen index was 24.5 ± 10.4, and mean PaO2/FiO2 was 80.6 ± 25. There was no difference in oxygen parameters at baseline the between two groups. There was a significant increase in PaO2/FiO2 (119.2 ± 41.1, 49.6 ± 30.6, P = 0.01*) response after 1 h of LVRM with HFOV compare to CV. Hemodynamic and serious complications were not significantly affected after LVRM. The overall PICU mortality of our severe ARDS at 28 days was 16.7%. Three patients in CV with LVRM group failed to wean oxygen requirement and were cross-over to HFOV group. CONCLUSIONS HFOV combined with LVRM in severe pediatric ARDS had superior oxygenation and tended to have better clinical effect over CV. There is no significant effect on hemodynamic parameters. Moreover, no serious complication was noted.
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Affiliation(s)
- Rujipat Samransamruajkit
- Division of Pediatric Critical Care, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Chavisa Rassameehirun
- Department of Pediatrics, Division of Pediatric Pulmonary, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Khemmachart Pongsanon
- Division of Pediatric Critical Care, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Sumalee Huntrakul
- Department of Pediatrics, Division of Pediatric Pulmonary, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Jitladda Deerojanawong
- Department of Pediatrics, Division of Pediatric Pulmonary, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Suchada Sritippayawan
- Department of Pediatrics, Division of Pediatric Pulmonary, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Nuanchan Prapphal
- Department of Pediatrics, Division of Pediatric Pulmonary, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, 10330, Thailand
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McCall KE, Davis PG, Owen LS, Tingay DG. Sustained lung inflation at birth: what do we know, and what do we need to know? Arch Dis Child Fetal Neonatal Ed 2016; 101:F175-80. [PMID: 26527635 DOI: 10.1136/archdischild-2015-309611] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/10/2015] [Indexed: 11/04/2022]
Abstract
A sustained inflation has been advocated as a potential method of augmenting lung aeration at birth. Clinical trials have suggested that a sustained inflation may lead to a reduced need for intubation and ventilation in the first few days of life, without cardiovascular compromise or increased lung injury. Despite this, a sustained inflation is not currently a standard of practice, mainly due to a lack of clarity regarding the optimal delivery method. Animal trials have sought to refine delivery techniques. This review will outline current recommendations regarding a sustained inflation, discuss potential strategies for its optimal delivery and suggest priorities for future research.
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Affiliation(s)
- Karen E McCall
- Newborn Research, Murdoch Children's Research Institute, Melbourne, Australia School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Peter G Davis
- Newborn Research, Murdoch Children's Research Institute, Melbourne, Australia Department of Obstetrics, University of Melbourne, Melbourne, Australia Neonatal Research, Royal Women's Hospital, Melbourne, Australia
| | - Louise S Owen
- Newborn Research, Murdoch Children's Research Institute, Melbourne, Australia Department of Obstetrics, University of Melbourne, Melbourne, Australia Neonatal Research, Royal Women's Hospital, Melbourne, Australia
| | - David G Tingay
- Newborn Research, Murdoch Children's Research Institute, Melbourne, Australia Neonatal Research, Royal Women's Hospital, Melbourne, Australia Department of Neonatology, Royal Children's Hospital, Melbourne, Australia Department of Paediatrics, University of Melbourne, Melbourne, Australia
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Tingay DG, Rajapaksa A, Zonneveld CE, Black D, Perkins EJ, Adler A, Grychtol B, Lavizzari A, Frerichs I, Zahra VA, Davis PG. Spatiotemporal Aeration and Lung Injury Patterns Are Influenced by the First Inflation Strategy at Birth. Am J Respir Cell Mol Biol 2016; 54:263-72. [DOI: 10.1165/rcmb.2015-0127oc] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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Determination of Lung Volume and Hemodynamic Changes During High-Frequency Ventilation Recruitment in Preterm Neonates With Respiratory Distress Syndrome. Crit Care Med 2015; 43:1685-91. [DOI: 10.1097/ccm.0000000000000967] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Tingay DG, John J, Harcourt ER, Black D, Dargaville PA, Mills JF, Davis PG. Are All Oscillators Created Equal? In vitro Performance Characteristics of Eight High-Frequency Oscillatory Ventilators. Neonatology 2015; 108:220-8. [PMID: 26304262 DOI: 10.1159/000431216] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 05/07/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND The mode of waveform generation and circuit characteristics differ between high-frequency oscillators. It is unknown if this influences performance. OBJECTIVES To describe the relationships between set and delivered pressure amplitude (x0394;P), and the interaction with frequency and endotracheal tube (ETT) diameter, in eight high-frequency oscillators. METHODS Oscillators were evaluated using a 70-ml test lung at 1.0 and 2.0 ml/cm H2O compliance, with mean airway pressures (PAW) of 10 and 20 cm H2O, frequencies of 5, 10 and 15 Hz, and an ETT diameter of 2.5 and 3.5 mm. At each permutation of PAW, frequency and ETT, the set x0394;P was sequentially increased from 15 to 50 cm H2O, or from 20 to 100% maximum amplitude (10% increments) depending on the oscillator design. The x0394;P at the ventilator (x0394;PVENT), airway opening (x0394;PAO) and within the test lung (x0394;PTRACH), and tidal volume (V(T)) at the airway opening were determined at each set x0394;P. RESULTS In two oscillators the relationships between set and delivered x0394;P were non-linear, with a plateau in x0394;P thresholds noted at all frequencies (Dräger Babylog 8000) or ≥10 Hz (Dräger VN500). In all other devices there was a linear relationship between x0394;PVENT, x0394;PAO and x0394;PTRACH (all r2 >0.93), with differing attenuation of the pressure wave. Delivered V(T) at the different settings tested varied between devices, with some unable to deliver V(T) >3 ml at 15 Hz, and others generating V(T)>20 ml at 5 Hz and a 1:1 inspiratory-to-expiratory time ratio. CONCLUSIONS Clinicians should be aware that modern high-frequency oscillators exhibit important differences in the delivered x0394;P and V(T).
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Affiliation(s)
- David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Vic., Australia
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Monitoring Lung Volumes During Mechanical Ventilation. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7193716 DOI: 10.1007/978-3-642-01219-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Respiratory inductive plethysmography (RIP) is a non-invasive method of measuring change in lung volume which is well-established as a monitor of tidal ventilation and thus respiratory patterns in sleep medicine. As RIP is leak independent, can measure end-expiratory lung volume as well as tidal volume and is applicable to both the ventilated and spontaneously breathing patient, there has been a recent interest in its use as a bedside tool in the intensive care unit.
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Setting the Ventilator in the NICU. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7122498 DOI: 10.1007/978-3-642-01219-8_42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Success in providing respiratory support to the neonate requires a clear understanding of the context in which it is being applied. Perhaps more than for any other age group, the array of different situations in which ventilation is applied to the newborn infant is extremely broad, with in each case different pathophysiological disturbances and often the need to use a specific approach to apply ventilation optimally. Table 42.1 provides a list of the more common situations in which conventional ventilation is used in the neonate and includes some considerations regarding ventilator settings for each situation. For each situation, a suggested mode of ventilation is indicated, along with target ranges for positive end-expiratory pressure (PEEP) and tidal volume (VT). Further discussion of the physiological rationale and available evidence for ventilator settings is set out below.
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Rimensberger PC. Clinical Use of Nonconventional Modes of Ventilator Support. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7193707 DOI: 10.1007/978-3-642-01219-8_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
High-frequency oscillatory ventilation (HFOV) is now a mainstay of respiratory care for the neonatal patient. In this chapter, we will define HFOV as those ventilators with a “true” active expiratory phase created by a piston or diaphragm. Jet ventilation and flow interrupters are discussed elsewhere in this book.
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Affiliation(s)
- Peter C. Rimensberger
- Service of Neonatology and Pediatric Intensive Care, Department of Pediatrics, University Hospital of Geneva, Geneve, Switzerland
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Cross-Sectional Changes in Lung Volume Measured by Electrical Impedance Tomography Are Representative for the Whole Lung in Ventilated Preterm Infants. Crit Care Med 2014; 42:1524-30. [DOI: 10.1097/ccm.0000000000000230] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Zannin E, Ventura ML, Dellacà RL, Natile M, Tagliabue P, Perkins EJ, Sourial M, Bhatia R, Dargaville PA, Tingay DG. Optimal mean airway pressure during high-frequency oscillatory ventilation determined by measurement of respiratory system reactance. Pediatr Res 2014; 75:493-9. [PMID: 24375086 DOI: 10.1038/pr.2013.251] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 09/24/2013] [Indexed: 11/09/2022]
Abstract
BACKGROUND The aims of the present study were (i) to characterize the relationship between mean airway pressure (PAW) and reactance measured at 5 Hz (reactance of the respiratory system (X RS), forced oscillation technique) and (ii) to compare optimal PAW (P opt) defined by X RS, oxygenation, lung volume (VL), and tidal volume (VT) in preterm lambs receiving high-frequency oscillatory ventilation (HFOV). METHODS Nine 132-d gestation lambs were commenced on HFOV at PAW of 14 cmH2O (P start). PAW was increased stepwise to a maximum pressure (P max) and subsequently sequentially decreased to the closing pressure (Pcl, oxygenation deteriorated) or a minimum of 6 cmH2O, using an oxygenation-based recruitment maneuver. X RS, regional V L (electrical impedance tomography), and V T were measured immediately after (t 0 min) and 2 min after (t 2 min) each PAW decrement. P opt defined by oxygenation, X RS, V L, and V T were determined. RESULTS The PAW-X RS and PAW-VT relationships were dome shaped with a maximum at Pcl+6 cmH2O, the same point as P opt defined by VL. Below Pcl+6 cmH2O, X RS became unstable between t 0 min and t 2 min and was associated with derecruitment in the dependent lung. P opt, as defined by oxygenation, was lower than the P opt defined by X RS, V L, or V T. CONCLUSION X RS has the potential as a bedside tool for optimizing PAW during HFOV.
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Affiliation(s)
- Emanuela Zannin
- Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano University, Milano, Italy
| | - Maria Luisa Ventura
- Neonatology and Neonatal Intensive Care Unit, Fondazione MBBM - Ospedale San Gerardo, Monza, Italy
| | - Raffaele L Dellacà
- Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano University, Milano, Italy
| | - Miria Natile
- Neonatology and Neonatal Intensive Care Unit, Fondazione MBBM - Ospedale San Gerardo, Monza, Italy
| | - Paolo Tagliabue
- Neonatology and Neonatal Intensive Care Unit, Fondazione MBBM - Ospedale San Gerardo, Monza, Italy
| | - Elizabeth J Perkins
- 1] Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia [2] Department of Neonatology, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Magdy Sourial
- Department of Neonatology, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Risha Bhatia
- Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Peter A Dargaville
- 1] Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia [2] Department of Paediatrics, Royal Hobart Hospital and University of Tasmania, Hobart, Tasmania, Australia [3] Neonatal Respiratory Group, Menzies Research Institute, Hobart, Tasmania, Australia
| | - David G Tingay
- 1] Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia [2] Department of Neonatology, Royal Children's Hospital, Melbourne, Victoria, Australia [3] Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
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Effect of sustained inflation vs. stepwise PEEP strategy at birth on gas exchange and lung mechanics in preterm lambs. Pediatr Res 2014; 75:288-94. [PMID: 24257321 DOI: 10.1038/pr.2013.218] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Accepted: 06/27/2013] [Indexed: 11/08/2022]
Abstract
BACKGROUND Sustained inflation (SI) at birth facilitates establishment of functional residual capacity (FRC) in the preterm lung, but the ideal lung recruitment strategy is unclear. We have compared the effect of SI and a stepwise positive end-expiratory pressure (PEEP; SEP) strategy in a preterm model. METHODS 127 d gestation lambs received either 20-s SI (n = 9) or 2 cmH2O stepwise PEEP increases to 20 cmH2O every 10 inflations, and then decreases to 6 cmH2O (n = 10). Ventilation continued for 70 min, with surfactant administered at 10 min. Alveolar-arterial oxygen gradient (AaDO2), compliance (C(dyn)), end-expiratory thoracic volume (EEVRIP; respiratory inductive plethysmography), and EEV and C(dyn) in the gravity-dependent and nondependent hemithoraces (electrical impedance tomography) were measured throughout. Early mRNA markers of lung injury were analyzed using quantitative real-time PCR. RESULTS From 15 min of life, AaDO2 was lower in SEP group (P < 0.005; two-way ANOVA). SEP resulted in higher and more homogeneous C(dyn) (P < 0.0001). Mean (SD) EEVRIP at 5 min was 18 (9) ml/kg and 6 (5) ml/kg following SEP and SI, respectively (P = 0.021; Bonferroni posttest); this difference was due to a greater nondependent hemithorax EEV. There was no difference in markers of lung injury. CONCLUSION An SEP at birth improved gas exchange, lung mechanics, and EEV, without increasing lung injury, compared to the SI strategy used.
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Tingay DG, Wallace MJ, Bhatia R, Schmölzer GM, Zahra VA, Dolan MJ, Hooper SB, Davis PG. Surfactant before the first inflation at birth improves spatial distribution of ventilation and reduces lung injury in preterm lambs. J Appl Physiol (1985) 2013; 116:251-8. [PMID: 24356523 DOI: 10.1152/japplphysiol.01142.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interrelationship between the role of surfactant and a sustained inflation (SI) to aid ex utero transition of the preterm lung is unknown. We compared the effect of surfactant administered before and after an initial SI on gas exchange, lung mechanics, spatial distribution of ventilation, and lung injury in preterm lambs. Gestational-age lambs (127 days; 9 per group) received 100 mg/kg of a surfactant (Curosurf) either prior (Surf+SI) or 10 min after birth (SI+Surf). At birth, a 20-s, 35 cmH2O SI was applied, followed by 70 min of positive pressure ventilation. Oxygenation, carbon dioxide removal, respiratory system compliance, end-expiratory thoracic volume (via respiratory inductive plethysmography), and distribution of end-expiratory volume and ventilation (via electrical impedance tomography) were measured throughout. Early markers of lung injury were analyzed using quantitative RT-PCR. During the first 15 min, oxygenation, carbon dioxide removal, and compliance were better in the Surf+SI group (all P < 0.05). End-expiratory volume on completion of the sustained inflation was higher in the Surf+SI group than the SI+Surf group; 11 ± 1 ml/kg vs. 7 ± 1 ml/kg (mean ± SE) (P = 0.043; t-test), but was not different at later time points. Although neither achieved homogenous aeration, spatial ventilation was more uniform in the Surf+SI group throughout; 50.1 ± 10.9% of total ventilation in the left hemithorax at 70 min vs. 42.6 ± 11.1% in the SI+Surf group. Surf+SI resulted in lower mRNA levels of CYR61 and EGR1 compared with SI+Surf (P < 0.001, one-way ANOVA). Surfactant status of the fetal preterm lung at birth influences the mechanical and injury response to a sustained inflation and ventilation by changing surface tension of the air/fluid interface.
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Affiliation(s)
- David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
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Schmölzer GM, Bhatia R, Davis PG, Tingay DG. A comparison of different bedside techniques to determine endotracheal tube position in a neonatal piglet model. Pediatr Pulmonol 2013; 48:138-45. [PMID: 22615185 DOI: 10.1002/ppul.22580] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 03/06/2012] [Indexed: 12/22/2022]
Abstract
RATIONALE Endotracheal tube (ETT) malposition is common and an increasing number of non-invasive techniques to aid rapid identification of tube position are available. Electrical impedance tomography (EIT) is advocated as a tool to monitor ventilation. OBJECTIVE This study aimed to compare EIT with five other non-invasive techniques for identifying ETT position in a piglet model. METHODOLOGY Six saline lavage surfactant-depleted piglets were studied. Periods of ventilation with ETT placed in the oesophagus or a main bronchus (MB) were compared with an appropriately placed mid-tracheal ETT. Colorimetric end-tidal CO(2) (Pedi-Cap®), SpO(2) and heart rate, tidal volume (${\rm V}_{{\rm T}_{{\rm ao}} } $) using a hot-wire anemometer at the airway opening, tidal volume using respiratory inductive plethysmography (${\rm V}_{{\rm T}_{{\rm RIP}} } $) and regional tidal ventilation within each hemithorax (EIT) were measured. RESULTS Oesophageal ventilation: Pedi-Cap® demonstrated absence of color change. ${\rm V}_{{\rm T}_{{\rm ao}} } $, ${\rm V}_{{\rm T}_{{\rm RIP}} } $, and EIT correctly demonstrated no tidal ventilation. SpO(2) decreased from mean (SD) 96 (2)% to 74 (12)% (P < 0.05; Bonferroni post-test), without heart rate change. MB ventilation: SpO(2) , heart rate and Pedi-Cap® were unchanged compared with mid-tracheal position. ${\rm V}_{{\rm T}_{{\rm ao}} } $ and ${\rm V}_{{\rm T}_{{\rm RIP}} } $ decreased from a mean (SD) 10.8 (5.6) ml/kg and 14.6 (6.2) ml/kg to 5.5 (1.9) ml/kg and 6.4 (2.6) ml/kg (both P < 0.05; Bonferroni post-test). EIT identified the side of MB ventilation, with a mean (SD) 95 (3)% reduction in tidal volume in the unventilated lung. CONCLUSIONS EIT not only correctly identified oesophageal ventilation but also localized the side of MB ventilation. At present, no one technique is without limitations and clinicians should utilize a combination in addition to clinical judgement.
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Affiliation(s)
- Georg M Schmölzer
- Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Australia.
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Indicators of Optimal Lung Volume During High-Frequency Oscillatory Ventilation in Infants*. Crit Care Med 2013; 41:237-44. [DOI: 10.1097/ccm.0b013e31826a427a] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
The lungs of an extremely preterm infant ≤28 weeks gestation are structurally and biochemically immature and vulnerable to injury from positive pressure ventilation. A lung protective approach to respiratory support is vital, aiming to ventilate an open lung, using the lowest pressure settings that maintain recruitment and oxygenation and avoiding hyperinflation with each tidal breath. For infants with severe respiratory distress syndrome and persistent atelectasis, lung protective ventilation requires recruitment using stepwise pressure increments, followed by reduction in ventilator pressures in search of an optimal point at which to maintain ventilation. Several studies, including a single randomised controlled trial, have found this lung protective strategy to be more effectively administered using high-frequency oscillatory ventilation rather than conventional ventilation. Many extremely preterm infants have minimal atelectasis and low oxygen requirements in the first days of life, and the ventilatory approach in this case should be one of avoidance of factors including overdistension that are known to contribute to later pulmonary deterioration. From a practical perspective, this means setting positive end-expiratory pressure at the lowest value that maintains oxygenation and restricting tidal volume using a volume-targeted mode of ventilation.
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Affiliation(s)
- Peter A Dargaville
- Department of Paediatrics, Royal Hobart Hospital and University of Tasmania, Hobart, Tasmania, Australia.
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Hepponstall JM, Tingay DG, Bhatia R, Loughnan PM, Copnell B. Effect of closed endotracheal tube suction method, catheter size, and post-suction recruitment during high-frequency jet ventilation in an animal model. Pediatr Pulmonol 2012; 47:749-56. [PMID: 22290736 DOI: 10.1002/ppul.21607] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Accepted: 11/03/2011] [Indexed: 11/10/2022]
Abstract
RATIONALE High-frequency jet ventilation (HFJV) is often used to treat infants with pathologies associated with gas trapping and abnormal lung mechanics, who are sensitive to the adverse effects of suction. OBJECTIVE This study aimed to investigate the effect of closed suction (CS), catheter size, and the use of active post-suction sighs on tracheal pressure (P(trach)), and global and regional end-expiratory lung volume (EELV) during HFJV. METHODS Six anaesthetized and muscle-relaxed adult rabbits were stabilized on HFJV. CS was performed using all permutations of three CS methods (Continual negative pressure, negative pressure applied during Withdrawal, and HFJV in Standby) and 6 French gauge (6 FG) and 8 French gauge (8 FG) catheter, randomly assigned. The sequence was repeated using post-suction sighs. P(trach), absolute (respiratory inductive plethysmography) and regional (electrical impedance tomography; expressed as percentage of vital capacity for the defined region of interest, %Z(VCroi) ) EELV were measured before, during and 60 sec post-suction. RESULTS CS methods exerted no difference on ΔP(trach), ΔEELV(RIP), or Δ%Z(VCroi) . 8FG catheter resulted in a mean (95%CI) 20.0 (17.9,22.2) cm H(2)O greater loss of P(trach) during suction compared to 6FG (Bonferroni post-test). Mean (± SD) ΔEELV(RIP) was -6(±3) and -2(±1) ml/kg with the 8 and 6 FG catheters (P < 0.0001; Bonferroni post-test). ΔEELV was 31.7 (21.1,42.4) %Z(VCroi) and 24.8 (10.9,38.7) %Z(VCroi) greater in the ventral and dorsal hemithoraces using the 8 FG. Only after 8 FG CS was post-suction recruitment required to restore EELV. CONCLUSIONS In this animal model receiving HFJV, ΔP(trach), ΔEELV, and need for post-suction recruitment during CS were most influenced by catheter size. Volume changes within the lung were uniform.
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Affiliation(s)
- J Michele Hepponstall
- Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria 3052, Australia.
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Singh R, Courtney SE, Weisner MD, Habib RH. Respiratory mechanics during high-frequency oscillatory ventilation: a physical model and preterm infant study. J Appl Physiol (1985) 2012; 112:1105-13. [DOI: 10.1152/japplphysiol.01120.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Accurate mechanics measurements during high-frequency oscillatory ventilation (HFOV) facilitate optimizing ventilator support settings. Yet, these are influenced substantially by endotracheal tube (ETT) contributions, which may dominate when leaks around uncuffed ETT are present. We hypothesized that 1) the effective removal of ETT leaks may be confirmed via direct comparison of measured vs. model-predicted mean intratracheal pressure [mPtr (meas) vs. mPtr (pred)], and 2) reproducible respiratory system resistance (Rrs) and compliance (Crs) may be derived from no-leak oscillatory Ptr and proximal flow. With the use of ETT test-lung models, proximal airway opening (Pao) and distal (Ptr) pressures and flows were measured during slow-cuff inflations until leaks are removed. These were repeated for combinations of HFOV settings [frequency, mean airway pressure (Paw), oscillation amplitudes (ΔP), and inspiratory time (%tI)] and varying test-lung Crs. Results showed that leaks around the ETT will 1) systematically reduce the effective distending pressures and lung-delivered oscillatory volumes, and 2) derived mechanical properties are increasingly nonphysiologic as leaks worsen. Mean pressures were systematically reduced along the ventilator circuit and ETT (Paw > Pao > Ptr), even for no-leak conditions. ETT size-specific regression models were then derived for predicting mPtr based on mean Pao (mPao), ΔP, %tI, and frequency. Next, in 10 of 11 studied preterm infants (0.77 ± 0.24 kg), no-to-minimal leak was confirmed based on excellent agreement between mPtr (meas) and mPtr (pred), and consequently, their oscillatory respiratory mechanics were evaluated. Infant resistance at the proximal ETT (RETT; resistance airway opening = RETT + Rrs; P < 0.001) and ETT inertance ( P = 0.014) increased significantly with increasing ΔP (50%, 100%, and 150% baseline), whereas Rrs showed a modest, nonsignificant increase ( P = 0.14), and Crs was essentially unchanged ( P = 0.39). We conclude that verifying no-leak conditions is feasible by comparison of model-derived vs. distending mPtr (meas). This facilitated the reliable and accurate assessment of physiologic respiratory mechanical properties that can objectively guide ventilatory management of HFOV-treated preterm infants.
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Affiliation(s)
- Rachana Singh
- Division of Newborn Medicine, Baystate Medical Center, Springfield, Massachusetts
| | - Sherry E. Courtney
- Division of Neonatology, Stony Brook University Medical Center, Stonybrook, New York
| | | | - Robert H. Habib
- Department of Internal Medicine, American University of Beirut, Beirut, Lebanon
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Bhatia R, Schmölzer GM, Davis PG, Tingay DG. Electrical impedance tomography can rapidly detect small pneumothoraces in surfactant-depleted piglets. Intensive Care Med 2011; 38:308-15. [DOI: 10.1007/s00134-011-2421-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 10/18/2011] [Indexed: 10/15/2022]
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Kneyber MCJ. High-frequency oscillatory ventilation and pediatric cardiac surgery: yes, we can! Crit Care 2011; 15:1011. [PMID: 22126408 PMCID: PMC3388685 DOI: 10.1186/cc10529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In the previous issue of Critical Care, Bojan and colleagues reported their experiences with high-frequency oscillatory ventilation (HFOV) after pediatric cardiac surgery. A total of 120 patients were treated with HFOV on the day of surgery, thus excluding rescue HFOV use. The main finding of the authors was that the duration of mechanical ventilation was significantly shorter in patients in whom HFOV was initiated on the day of surgery. Especially interesting about this work is that the authors used HFOV when there was evidence of pulmonary hypertension or right ventricular (RV) failure in their patients. This is an interesting approach as it is often assumed that high intra-thoracic pressures increase RV afterload and thus may enhance RV dysfunction. The findings of Bojan and colleagues may be explained by the fact that they were able to decrease the pulmonary vascular resistance by finding a proper balance between atelectasis and overdistension of the lung. It can be argued that it is possible to do so by applying positive end-expiratory pressure. But, at the same time, this may coincide with the delivery of high inspiratory pressures (>30 cm H2O). As HFOV is, in fact, a continuous positive airway pressure system, its advantage is that it is possible to maintain sufficient lung volume without large injurious pressure swings. Although the observations by Bojan and colleagues need to be confirmed in a prospective randomized trial, they have provided arguments not to rule out the early use of HFOV in pediatric cardiac surgery patients.
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Early detection of deteriorating ventilation by monitoring bilateral chest wall dynamics in the rabbit. Intensive Care Med 2011; 38:120-7. [PMID: 22105962 DOI: 10.1007/s00134-011-2398-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 08/29/2011] [Indexed: 10/15/2022]
Abstract
PURPOSE Mechanical complications during assisted ventilation can evolve due to worsening lung disease or problems in airway management. These complications affect lung compliance or airway resistance, which in turn affect the chest wall dynamics. The objective of this study was to explore the utility of continuous monitoring of the symmetry and dynamics of chest wall motion in the early detection of complications during mechanical ventilation. METHODS The local tidal displacement (TDi) values of each side of the chest and epigastrium were measured by three miniature motion sensors in 18 rabbits. The TDi responses to changes in peak inspiratory pressure (n = 7), induction of one-lung intubation (n = 7), and slowly progressing pneumothorax (PTX) (n = 6) were monitored in parallel with conventional respiratory (SpO(2), EtCO(2), pressure and flow) and hemodynamic (HR and BP) indices. PTX was induced by injecting air into the pleural space at a rate of 1 mL/min. RESULTS A strong correlation (R(2) = 0.99) with a slope close to unity (0.94) was observed between percent change in tidal volume and in TDi. One-lung ventilation was identified by conspicuous asymmetry development between left and right TDis. These indices provided significantly early detection of uneven ventilation during slowly developing PTX (within 12.9 ± 6.6 min of onset, p = 0.02) almost 1 h before the SpO(2) dropped (77.3 ± 27.4 min, p = 0.02). Decreases in TDi of the affected side paralleled the progression of PTX. CONCLUSIONS Monitoring the local TDi is a sensitive method for detecting changes in tidal volume and enables early detection of developing asymmetric ventilation.
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