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Haudebourg AF, Maraffi T, Tuffet S, Le Corvoisier P, Mekontso Dessap A, Carteaux G. Influence of different noninvasive oxygenation support devices on tidal volume. Ann Intensive Care 2023; 13:116. [PMID: 38006434 PMCID: PMC10676331 DOI: 10.1186/s13613-023-01200-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 09/30/2023] [Indexed: 11/27/2023] Open
Abstract
BACKGROUND Multiple devices are available for noninvasive oxygenation support, including non-rebreather oxygen mask (O2-mask), high-flow oxygen through nasal cannula (HFNC), continuous positive airway pressure (CPAP), mask noninvasive ventilation (Mask-NIV) and helmet NIV (Helmet-NIV). As tidal volume is a key determinant of efficacy and safety during ventilatory support, we assessed whether it was influenced by the type of noninvasive oxygenation device. METHODS A bench study using a manikin with a realistic face connected to a lung simulator was performed. Six conditions were assessed: no device, O2-mask, HFNC, CPAP, Mask-NIV and Helmet-NIV. Three respiratory mechanics were simulated (normal, obstructive, restrictive), at three simulated efforts (low, moderate, respiratory distress). Flow was recorded at the lung simulator inlet and mouth pressure into the manikin mouth. The same devices were evaluated on healthy volunteers with tidal volume assessed by electrical impedance tomography (EIT). RESULTS Tidal volume was significantly influenced by oxygenation devices in bench model. As compared to O2-mask, HFNC and CPAP delivered significantly lower tidal volumes (440 ± 352 mL, 414 ± 333 mL and 377 ± 297 mL, respectively), while Mask-NIV or Helmet-NIV were associated with significantly higher tidal volumes (690 ± 321 mL and 652 ± 366 mL, respectively). Tidal volume was strongly correlated with the specific effect of each device on mouth pressure during inspiration: HFNC and CPAP were characterized by a negative PTPmouth (- 0.3 [- 0.8 to - 0.2] and - 0.7 [- 2.2 to - 0.5] cmH2O.sec/cycle, respectively), while Helmet-NIV and Mask-NIV were associated with a positive PTPmouth (4.5 [4.1-4.6] and 6.1 [5.9-7.1] cmH2O.sec/cycle, respectively). Tidal volume was also significantly influenced by oxygenation devices in healthy volunteers, with similar tidal volumes between O2-mask and CPAP (644 [571-764] and 648 [586-770] mL) but higher with HFNC, Mask-NIV and Helmet-NIV (819 [609-918], 1110 [661-1305] and 1086 [833-1243] mL). CONCLUSIONS Tidal volume is significantly influenced by noninvasive oxygenation support devices, with a strong correlation with the pressure variation generated into the mouth during inspiration. NIV was associated with the highest tidal volumes and CPAP with the lowest ones. Clinical studies are needed to clarify the clinical implications of these effects.
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Affiliation(s)
- Anne-Fleur Haudebourg
- Service de Médecine Intensive Réanimation, Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor - Albert Chenevier, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France.
- Faculté de Santé, Groupe de Recherche Clinique CARMAS, Université Paris Est-Créteil, 94010, Créteil, France.
| | - Tommaso Maraffi
- Service de Réanimation Adultes Et Surveillance Continue, Centre Hospitalier Intercommunal Créteil, 40, Avenue de Verdun, 94000, Créteil, France
| | - Samuel Tuffet
- Service de Médecine Intensive Réanimation, Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor - Albert Chenevier, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France
- Faculté de Santé, Groupe de Recherche Clinique CARMAS, Université Paris Est-Créteil, 94010, Créteil, France
| | - Philippe Le Corvoisier
- Centre d'Investigation Clinique 1430, Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor - Albert Chenevier, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France
| | - Armand Mekontso Dessap
- Service de Médecine Intensive Réanimation, Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor - Albert Chenevier, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France
- Faculté de Santé, Groupe de Recherche Clinique CARMAS, Université Paris Est-Créteil, 94010, Créteil, France
- INSERM U955, Institut Mondor de Recherche Biomédicale, 94010, Créteil, France
| | - Guillaume Carteaux
- Service de Médecine Intensive Réanimation, Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor - Albert Chenevier, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France
- Faculté de Santé, Groupe de Recherche Clinique CARMAS, Université Paris Est-Créteil, 94010, Créteil, France
- INSERM U955, Institut Mondor de Recherche Biomédicale, 94010, Créteil, France
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Liu L, Li HL, Lu C, Patel P, Wang D, Beck J, Sinderby C. Estimation of transpulmonary driving pressure during synchronized mechanical ventilation using a single lower assist maneuver (LAM) in rabbits: a comparison to measurements made with an esophageal balloon. Crit Care 2023; 27:325. [PMID: 37626372 PMCID: PMC10463600 DOI: 10.1186/s13054-023-04607-2] [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] [Received: 04/17/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
BACKGROUND Mechanical ventilation is applied to unload the respiratory muscles, but knowledge about transpulmonary driving pressure (ΔPL) is important to minimize lung injury. We propose a method to estimate ΔPL during neurally synchronized assisted ventilation, with a simple intervention of lowering the assist for one breath ("lower assist maneuver", LAM). METHODS In 24 rabbits breathing spontaneously with imposed loads, titrations of increasing assist were performed, with two neurally synchronized modes: neurally adjusted ventilatory assist (NAVA) and neurally triggered pressure support (NPS). Two single LAM breaths (not sequentially, but independently) were performed at each level of assist by acutely setting the assist to zero cm H2O (NPS) or NAVA level 0 cm H2O/uV (NAVA) for one breath. NPS and NAVA titrations were followed by titrations in controlled-modes (volume control, VC and pressure control, PC), under neuro-muscular blockade. Breaths from the NAVA/NPS titrations were matched (for flow and volume) to VC or PC. Throughout all runs, we measured diaphragm electrical activity (Edi) and esophageal pressure (PES). We measured ΔPL during the spontaneous modes (PL_PES) and controlled mechanical ventilation (CMV) modes (PL_CMV) with the esophageal balloon. From the LAMs, we derived an estimation of ΔPL ("PL_LAM") using a correction factor (ratio of volume during the LAM and volume during assist) and compared it to measured ΔPL during passive (VC or PC) and spontaneous breathing (NAVA or NPS). A requirement for the LAM was similar Edi to the assisted breath. RESULTS All animals successfully underwent titrations and LAMs for NPS/NAVA. One thousand seven-hundred ninety-two (1792) breaths were matched to passive ventilation titrations (matched Vt, r = 0.99). PL_LAM demonstrated strong correlation with PL_CMV (r = 0.83), and PL_PES (r = 0.77). Bland-Altman analysis revealed little difference between the predicted PL_LAM and measured PL_CMV (Bias = 0.49 cm H2O and 1.96SD = 3.09 cm H2O). For PL_PES, the bias was 2.2 cm H2O and 1.96SD was 3.4 cm H2O. Analysis of Edi and PES at peak Edi showed progressively increasing uncoupling with increasing assist. CONCLUSION During synchronized mechanical ventilation, a LAM breath allows for estimations of transpulmonary driving pressure, without measuring PES, and follows a mathematical transfer function to describe respiratory muscle unloading during synchronized assist.
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Affiliation(s)
- Ling Liu
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, 210009, China
| | - Hong-Liang Li
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Cong Lu
- Institute of Medical Science, University of Toronto, Toronto, Canada
- Department of Critical Care, St. Michael's Hospital, Keenan Research Centre for Biomedical Science of St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada
| | - Purab Patel
- Department of Critical Care, St. Michael's Hospital, Keenan Research Centre for Biomedical Science of St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada
| | - Danqiong Wang
- Department of Critical Care Medicine, The Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou, 324000, China
| | - Jennifer Beck
- Department of Critical Care, St. Michael's Hospital, Keenan Research Centre for Biomedical Science of St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada.
- Department of Pediatrics, University of Toronto, Toronto, Canada.
- Member, Institute for Biomedical Engineering and Science Technology (iBEST) at Ryerson University and St-Michael's Hospital, Toronto, Canada.
| | - Christer Sinderby
- Department of Critical Care, St. Michael's Hospital, Keenan Research Centre for Biomedical Science of St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada
- Member, Institute for Biomedical Engineering and Science Technology (iBEST) at Ryerson University and St-Michael's Hospital, Toronto, Canada
- Department of Medicine and Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
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Quantifying ventilator unloading in CPAP ventilation. Comput Biol Med 2022; 142:105225. [PMID: 35032739 DOI: 10.1016/j.compbiomed.2022.105225] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 01/04/2022] [Accepted: 01/04/2022] [Indexed: 11/21/2022]
Abstract
BACKGROUND The intrinsic (muscular) patient effort driving inspiration in non-invasive ventilation modes, such as continuous positive airway pressure (CPAP) therapy, has not been identified from non-invasive data. Current CPAP settings are based on clinical judgment and assessment of symptoms of respiratory distress. Non-optimal settings, including too much positive end expiratory pressure (PEEP) can cause unintended lung injury and ventilator unloading, where patient effort drops and the CPAP device enables too much work being imposed on the injured lung. Currently, there is no non-invasive means of quantifying or identifying these effects. METHODS A novel model-based method of ascertaining intrinsic patient work of breathing (WOB) in CPAP is developed based on linear single compartment and 2nd order b-spline models previously used in invasive ventilation modes. Results are compared to current clinical indications, such as total Imposed WOB from the CPAP device and beak length, the latter of which is the clinical metric used to indicate alveolar overdistension. Intrinsic and Imposed WOB are compared. The hypothesis is that ventilator unloading can be assessed as a decrease in Intrinsic WOB relative to Imposed WOB, as PEEP and associated ventilator unloading rise. This hypothesis is tested using 14 subjects from a CPAP trial of several breathing rates at two PEEP levels. RESULTS The ratio of Intrinsic to Imposed WOB, normalised per unit tidal volume, decreased with increasing PEEP (4-7 cm H2O), capturing the expected trend of ventilator unloading. Ventilator unloading was observed across all breathing rates. Beak length measurements showed no conclusive evidence of capturing overdistension at higher PEEP or ventilator unloading. CONCLUSIONS Patient Intrinsic WOB in CPAP was non-invasively quantified using model-based methods, based on pressure and flow measurements. The ratio of Intrinsic to Imposed WOB per unit tidal volume clearly and consistently showed ventilator unloading across all patients and breathing rates, with Intrinsic WOB decreasing with increasing PEEP. This trend was not observed in the current clinical metric of beak length. Non-invasively quantifying Intrinsic WOB and ventilator unloading is the critical first step to objectively optimising clinical CPAP settings, patient care, and outcomes.
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Knopp JL, Chase JG, Kim KT, Shaw GM. Model-based estimation of negative inspiratory driving pressure in patients receiving invasive NAVA mechanical ventilation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 208:106300. [PMID: 34348200 DOI: 10.1016/j.cmpb.2021.106300] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 07/17/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Optimisation of mechanical ventilation (MV) and weaning requires insight into underlying patient breathing effort. Current identifiable models effectively describe lung mechanics, such as elastance (E) and resistance (R) at the bedside in sedated patients, but are less effective when spontaneous breathing is present. This research derives and regularises a single compartment model to identify patient-specific inspiratory effort. METHODS Constrained second-order b-spline basis functions (knot width 0.05 s) are used to describe negative inspiratory drive (Pp, cmH2O) as a function of time. Breath-breath Pp are identified with single E and R values over inspiration and expiration from n = 20 breaths for N = 22 patients on NAVA ventilation. Pp is compared to measured electrical activity of the diaphragm (Eadi) and published results. RESULTS Average per-patient root-mean-squared model fit error was (median [interquartile range, IQR]) 0.9 [0.6-1.3] cmH2O, and average per-patient median Pp was -3.9 [-4.5- -3.0] cmH2O, with range -7.9 - -1.9 cmH2O. Per-patient E and R were 16.4 [13.6-21.8] cmH2O/L and 9.2 [6.4-13.1] cmH2O.s/L, respectively. Most patients showed an inspiratory volume threshold beyond which Pp started to return to baseline, and Pp at peak Eadi (end-inspiration) was often strongly correlated with peak Eadi (R2=0.25-0.86). Similarly, average transpulmonary pressure was consistent breath-breath in most patients, despite differences in peak Eadi and thus peak airway pressure. CONCLUSIONS The model-based inspiratory effort aligns with electrical muscle activity and published studies showing neuro-muscular decoupling as a function of pressure and/or volume. Consistency in coupling/dynamics were patient-specific. Quantification of patient and ventilator work of breathing contributions may aid optimisation of MV modes and weaning.
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Affiliation(s)
- Jennifer L Knopp
- Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
| | - J Geoffrey Chase
- Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Kyeong Tae Kim
- Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Geoffrey M Shaw
- Department of Intensive Care, Christchurch Hospital, Private Bag 4710, Christchurch, New Zealand
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Akoumianaki E, Vaporidi K, Georgopoulos D. The Injurious Effects of Elevated or Nonelevated Respiratory Rate during Mechanical Ventilation. Am J Respir Crit Care Med 2019; 199:149-157. [PMID: 30199652 DOI: 10.1164/rccm.201804-0726ci] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Respiratory rate is one of the key variables that is set and monitored during mechanical ventilation. As part of increasing efforts to optimize mechanical ventilation, it is prudent to expand understanding of the potential harmful effects of not only volume and pressures but also respiratory rate. The mechanisms by which respiratory rate may become injurious during mechanical ventilation can be distinguished in two broad categories. In the first, well-recognized category, concerning both controlled and assisted ventilation, the respiratory rate per se may promote ventilator-induced lung injury, dynamic hyperinflation, ineffective efforts, and respiratory alkalosis. It may also be misinterpreted as distress delaying the weaning process. In the second category, which concerns only assisted ventilation, the respiratory rate may induce injury in a less apparent way by remaining relatively quiescent while being challenged by chemical feedback. By responding minimally to chemical feedback, respiratory rate leaves the control of V. e almost exclusively to inspiratory effort. In such cases, when assist is high, weak inspiratory efforts promote ineffective triggering, periodic breathing, and diaphragmatic atrophy. Conversely, when assist is low, diaphragmatic efforts are intense and increase the risk for respiratory distress, asynchronies, ventilator-induced lung injury, diaphragmatic injury, and cardiovascular complications. This review thoroughly presents the multiple mechanisms by which respiratory rate may induce injury during mechanical ventilation, drawing the attention of critical care physicians to the potential injurious effects of respiratory rate insensitivity to chemical feedback during assisted ventilation.
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Affiliation(s)
- Evangelia Akoumianaki
- 1 Intensive Care Medicine Department, University Hospital of Heraklion, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Katerina Vaporidi
- 1 Intensive Care Medicine Department, University Hospital of Heraklion, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Dimitris Georgopoulos
- 1 Intensive Care Medicine Department, University Hospital of Heraklion, Medical School, University of Crete, Heraklion, Crete, Greece
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Effect of inspiratory synchronization during pressure-controlled ventilation on lung distension and inspiratory effort. Ann Intensive Care 2017; 7:100. [PMID: 28986852 PMCID: PMC5630544 DOI: 10.1186/s13613-017-0324-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 09/19/2017] [Indexed: 12/22/2022] Open
Abstract
Background In pressure-controlled (PC) ventilation, tidal volume (VT) and transpulmonary pressure (PL) result from the addition of ventilator pressure and the patient’s inspiratory effort. PC modes can be classified into fully, partially, and non-synchronized modes, and the degree of synchronization may result in different VT and PL despite identical ventilator settings. This study assessed the effects of three PC modes on VT, PL, inspiratory effort (esophageal pressure–time product, PTPes), and airway occlusion pressure, P0.1. We also assessed whether P0.1 can be used for evaluating patient effort. Methods Prospective, randomized, crossover physiologic study performed in 14 spontaneously breathing mechanically ventilated patients recovering from acute respiratory failure (1 subsequently withdrew). PC modes were fully (PC-CMV), partially (PC-SIMV), and non-synchronized (PC-IMV using airway pressure release ventilation) and were applied randomly; driving pressure, inspiratory time, and set respiratory rate being similar for all modes. Airway, esophageal pressure, P0.1, airflow, gas exchange, and hemodynamics were recorded. Results VT was significantly lower during PC-IMV as compared with PC-SIMV and PC-CMV (387 ± 105 vs 458 ± 134 vs 482 ± 108 mL, respectively; p < 0.05). Maximal PL was also significantly lower (13.3 ± 4.9 vs 15.3 ± 5.7 vs 15.5 ± 5.2 cmH2O, respectively; p < 0.05), but PTPes was significantly higher in PC-IMV (215.6 ± 154.3 vs 150.0 ± 102.4 vs 130.9 ± 101.8 cmH2O × s × min−1, respectively; p < 0.05), with no differences in gas exchange and hemodynamic variables. PTPes increased by more than 15% in 10 patients and by more than 50% in 5 patients. An increased P0.1 could identify high levels of PTPes. Conclusions Non-synchronized PC mode lowers VT and PL in comparison with more synchronized modes in spontaneously breathing patients but can increase patient effort and may need specific adjustments. Clinical Trial Registration Clinicaltrial.gov # NCT02071277 Electronic supplementary material The online version of this article (doi:10.1186/s13613-017-0324-z) contains supplementary material, which is available to authorized users.
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Becher T, Schädler D, Rostalski P, Zick G, Frerichs I, Weiler N. Determination of respiratory system compliance during pressure support ventilation by small variations of pressure support. J Clin Monit Comput 2017; 32:741-751. [DOI: 10.1007/s10877-017-0063-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 09/16/2017] [Indexed: 10/18/2022]
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Comparing changing neurally adjusted ventilatory assist (NAVA) levels in intubated and recently extubated neonates. J Perinatol 2016; 36:1097-1100. [PMID: 27629375 DOI: 10.1038/jp.2016.152] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 07/26/2016] [Accepted: 08/10/2016] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Neurally adjusted ventilatory assist (NAVA) is a mode of mechanical ventilation that delivers ventilatory support in synchrony to the patient's respiratory needs using NAVA level, a proportionality constant that converts the electrical activity of the diaphragm (Edi) into a peak pressure (PIP). Recent published studies suggest that neonates can control the delivered ventilatory support through neural feedback. Systematically increasing the NAVA level initially increases the PIP while maintaining a constant Edi until an inflection point or breakpoint (BrP) is reached, at which time the PIP plateaus and the Edi signal decreases. This study was performed to establish if there is a correlation of pre- and post-extubation BrP in premature neonates. STUDY DESIGN NAVA level was increased by 0.5 cm H2O mcV-1 every 3 min from 0.1 to 3.0 cm H2O mcV-1. PIP and Edi Peak and Minimum were recorded. STATISTICS PIP and phasic Edi (Edi peak-Edi min) were averaged for each NAVA level, plotted on a graph, and the BrP was determined by visual inspection of the inflection point for PIP. The data from the studies were then combined by averaging each variable at the BrP and for each change in NAVA level above and below the BrP. RESULTS Fifteen infants were studied for paired titration studies. PIP increased until the BrP was reached and then plateaued during both the intubated and extubated titration studies. Edi decreased after the BrP was reached during the titration studies. The BrP increased when patients were extubated from NAVA to noninvasive (NIV) NAVA. As the NAVA level rose above the BrP, PIP plateaued at a higher level and Edi decreased less during the NIV NAVA titration study. CONCLUSIONS Neonates demonstrated an increase in BrP, higher PIP and Edi when extubated from NAVA to NIV NAVA. This is most likely owing to the inefficiencies of NIV ventilation and suggests that neonates require a higher NAVA level when transitioning from NAVA to NIV NAVA.
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Comparison Between Neurally Adjusted Ventilatory Assist and Pressure Support Ventilation Levels in Terms of Respiratory Effort. Crit Care Med 2016; 44:503-11. [PMID: 26540399 DOI: 10.1097/ccm.0000000000001418] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To understand the potential equivalence between neurally adjusted ventilatory assist and pressure support ventilation levels in terms of respiratory muscle unloading. To compare the respiratory pattern, variability, synchronization, and neuromuscular coupling within comparable ranges of assistance. DESIGN Prospective single-center physiologic study. SETTING A 13-bed university medical ICU. PATIENTS Eleven patients recovering from respiratory failure. INTERVENTIONS The following levels of assistance were consecutively applied in a random order: neurally adjusted ventilatory assist levels: 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, and 7 cm H2O/μvolt; pressure support levels: 7, 10, 15, 20, and 25 cm H2O. MEASUREMENTS AND MAIN RESULTS Flow, airway pressure, esophageal pressures, and peak electrical activity of the diaphragm were continuously recorded. Breathing effort was calculated. To express the percentage of assist assumed by the ventilator, the total pressure including muscular and ventilator pressure was calculated. The median percentage of assist ranged from 33% (24-47%) to 82% (72-90%) between pressure support 7 and 25 cm H2O. Similar levels of unloading were observed for neurally adjusted ventilatory assist levels from 0.5 cm H2O/μvolt (46% [40-51%]) to 2.5 cm H2O/μvolt (80% [74-84%]). Tidal variability was higher during neurally adjusted ventilatory assist and ineffective efforts appeared only in pressure support. In neurally adjusted ventilatory assist, double triggering occurred sometimes when electrical activity of the diaphragm signal depicted a biphasic aspect, and an abnormal oscillatory pattern was frequently observed from 4 cm H2O/μvolt. For both modes, the relationship between peak electrical activity of the diaphragm and muscle pressure depicted a curvilinear profile. CONCLUSIONS In patients recovering from acute respiratory failure, levels of neurally adjusted ventilatory assist between 0.5 and 2.5 cm H2O/μvolt are comparable to pressure support levels ranging from 7 to 25 cm H2O in terms of respiratory muscle unloading. Neurally adjusted ventilatory assist provides better patient-ventilator interactions but can be sometimes excessively sensitive to electrical activity of the diaphragm in terms of triggering.
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Firestone KS, Fisher S, Reddy S, White DB, Stein HM. Effect of changing NAVA levels on peak inspiratory pressures and electrical activity of the diaphragm in premature neonates. J Perinatol 2015; 35:612-6. [PMID: 25764328 DOI: 10.1038/jp.2015.14] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 01/02/2015] [Accepted: 02/02/2015] [Indexed: 11/09/2022]
Abstract
BACKGROUND Neurally adjusted ventilator assist (NAVA) uses electrical activity of the diaphragm (Edi) to provide patient-directed ventilatory support. The NAVA level determines the proportional amount of ventilatory support. Systematically increasing NAVA level initially increases peak inspiratory pressure (PIP) while maintaining a constant Edi until a breakpoint (BrP) is reached. Further increases in NAVA level reduce the Edi, while the PIP plateaus. This study was performed to establish whether premature neonates have intact neural feedback systems allowing them to have a BrP. METHOD NAVA level was increased by 0.5 cm H2O μV(-1) every 3 min from 0.5 to 4.0 cm H2O μV(-1). PIP, Edi, mean blood pressure, heart rate, respiratory rate, oxygen saturation and FIO2 were recorded. Statistics: Non-linear regression was done for PIP and Edi. Linear regression was done for the other variables. The data from the trials were combined by normalizing to NAVA levels above and below the BrP. RESULT Nine neonates were studied on NAVA and 12 on non-invasive NAVA. PIP increased until the BrP was reached and then remained unchanged. Edi decreased after the BrP was reached. All other variables remained unchanged. CONCLUSION Neonates demonstrated a BrP suggesting intact neural feedback mechanisms that may protect lungs from over distention with NAVA ventilation.
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Affiliation(s)
- K S Firestone
- Neonatology, Akron Children's Hospital, Akron, OH, USA
| | - S Fisher
- Promedica Physician Group, Blissfield, MI, USA
| | - S Reddy
- Dayton Gastroenterology, Beavercreek, OH, USA
| | - D B White
- Mathematics and Statistics, The University of Toledo, Toledo, OH, USA
| | - H M Stein
- Neonatology, Promedica Toledo Children's Hospital, Toledo, OH, USA
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Liu L, Liu S, Xie J, Yang Y, Slutsky AS, Beck J, Sinderby C, Qiu H. Assessment of patient-ventilator breath contribution during neurally adjusted ventilatory assist in patients with acute respiratory failure. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:43. [PMID: 25882607 PMCID: PMC4339109 DOI: 10.1186/s13054-015-0775-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 01/07/2015] [Indexed: 12/18/2022]
Abstract
INTRODUCTION We previously showed in animals that the ratio of inspired tidal volume (Vtinsp) to inspiratory peak electrical activity of the diaphragm (EAdipk) can be used to quantify the respective patient and ventilator breath contributions (PVBCs) during neurally adjusted ventilatory assist (NAVA). The PVBC index has not been tested clinically. METHODS We studied 12 intubated and mechanically ventilated patients with acute respiratory failure and measured EAdipk, airway (Paw) and inspiratory esophageal pressure (Pes) and Vtinsp. We applied 11 different NAVA levels, increasing them every 3 minutes in steps of 0.3 cm H₂O/μV from 0 to 3.0 cmH₂O/μV. At each NAVA level, one breath was non-assisted (NAVA level 0). PVBC indices were calculated by relating Vtinsp/EAdipk of the non-assisted breath to Vtinsp/EAdipk of the assisted breath(s) using one ((N1)PVBC) or the mean value of five preceding assisted breaths ((X5)PVBC). During assisted breaths, inspiratory changes in Pes (∆Pes) and transpulmonary (ΔPtp) pressures were used to calculate the relative contribution of patient to total inspiratory lung-distending pressures (ΔPes/ΔPtp). Matching of respiratory drive indices and squaring of the PVBC was evaluated for their effect on the correlation between PVBC and ΔPes/ΔPtp. Linear regression analysis and Bland-Altman analysis were applied to compare indices. RESULTS Using an average of five assisted breaths prior to the non-assisted breath and squaring the PVBC ((X5)PVBC(2)) improved determination coefficients (P <0.05), adjusted the regression slope and intercept between PVBC and ΔPes/ΔPtp toward identity (P <0.05) and reduced bias (P <0.05). Matching EAdipk between non-assisted and assisted breaths within the range of 0.77 to 1.30 improved the relationship between (X5)PVBC(2) and ΔPes/ΔPtp (P <0.05) and abolished the need for EAdi normalization in the PVBC calculation (R(2) = 0.96; bias = 0.16 ± 0.06; precision = 0.33 ± 0.08 (mean and 95% confidence interval)). CONCLUSIONS This clinical study confirms previous experimental results showing that the PVBC(2) predicts the contribution of the inspiratory muscles versus that of the ventilator during NAVA, when differences in effort (EAdi) between non-assisted and assisted breaths are limited. PVBC could help to quantify and standardize the adjustment of the level of assist, and hence reduce the risks of excessive ventilatory assist in patients. TRIAL REGISTRATION ClinicalTrials.gov NCT01663480. Registered 9 August 2012.
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Affiliation(s)
- Ling Liu
- Department of Critical Care Medicine, Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China.
| | - Songqiao Liu
- Department of Critical Care Medicine, Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China.
| | - Jianfeng Xie
- Department of Critical Care Medicine, Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China.
| | - Yi Yang
- Department of Critical Care Medicine, Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China.
| | - Arthur S Slutsky
- Keenan Research Centre for Biomedical Science and Department of Critical Care, St Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada. .,Department of Medicine and Interdepartmental Division of Critical Care Medicine, University of Toronto, Suit RFE3-805, 200 Elizabeth Street, Toronto, ON, M5G 2C4, Canada.
| | - Jennifer Beck
- Keenan Research Centre for Biomedical Science and Department of Critical Care, St Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada. .,Department of Pediatrics, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
| | - Christer Sinderby
- Keenan Research Centre for Biomedical Science and Department of Critical Care, St Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada. .,Department of Medicine and Interdepartmental Division of Critical Care Medicine, University of Toronto, Suit RFE3-805, 200 Elizabeth Street, Toronto, ON, M5G 2C4, Canada.
| | - Haibo Qiu
- Department of Critical Care Medicine, Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China.
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Moorhead KT, Piquilloud L, Lambermont B, Roeseler J, Chiew YS, Chase JG, Revelly JP, Bialais E, Tassaux D, Laterre PF, Jolliet P, Sottiaux T, Desaive T. NAVA enhances tidal volume and diaphragmatic electro-myographic activity matching: a Range90 analysis of supply and demand. J Clin Monit Comput 2012; 27:61-70. [DOI: 10.1007/s10877-012-9398-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 09/15/2012] [Indexed: 10/27/2022]
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Piquilloud L, Tassaux D, Bialais E, Lambermont B, Sottiaux T, Roeseler J, Laterre PF, Jolliet P, Revelly JP. Neurally adjusted ventilatory assist (NAVA) improves patient-ventilator interaction during non-invasive ventilation delivered by face mask. Intensive Care Med 2012; 38:1624-31. [PMID: 22885649 DOI: 10.1007/s00134-012-2626-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 06/16/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE To determine if, compared to pressure support (PS), neurally adjusted ventilatory assist (NAVA) reduces patient-ventilator asynchrony in intensive care patients undergoing noninvasive ventilation with an oronasal face mask. METHODS In this prospective interventional study we compared patient-ventilator synchrony between PS (with ventilator settings determined by the clinician) and NAVA (with the level set so as to obtain the same maximal airway pressure as in PS). Two 20-min recordings of airway pressure, flow and electrical activity of the diaphragm during PS and NAVA were acquired in a randomized order. Trigger delay (T(d)), the patient's neural inspiratory time (T(in)), ventilator pressurization duration (T(iv)), inspiratory time in excess (T(iex)), number of asynchrony events per minute and asynchrony index (AI) were determined. RESULTS The study included 13 patients, six with COPD, and two with mixed pulmonary disease. T(d) was reduced with NAVA: median 35 ms (IQR 31-53 ms) versus 181 ms (122-208 ms); p = 0.0002. NAVA reduced both premature and delayed cyclings in the majority of patients, but not the median T(iex) value. The total number of asynchrony events tended to be reduced with NAVA: 1.0 events/min (0.5-3.1 events/min) versus 4.4 events/min (0.9-12.1 events/min); p = 0.08. AI was lower with NAVA: 4.9 % (2.5-10.5 %) versus 15.8 % (5.5-49.6 %); p = 0.03. During NAVA, there were no ineffective efforts, or late or premature cyclings. PaO(2) and PaCO(2) were not different between ventilatory modes. CONCLUSION Compared to PS, NAVA improved patient ventilator synchrony during noninvasive ventilation by reducing T(d) and AI. Moreover, with NAVA, ineffective efforts, and late and premature cyclings were absent.
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Affiliation(s)
- Lise Piquilloud
- Intensive Care and Burn Unit, University Hospital of Lausanne (CHUV), Lausanne, Switzerland.
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Neurally adjusted ventilatory assist improves patient–ventilator interaction in infants as compared with conventional ventilation. Pediatr Res 2012; 72:194-202. [PMID: 22580718 DOI: 10.1038/pr.2012.64] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Neurally adjusted ventilatory assist (NAVA) is a mode of ventilation controlled by the electrical activity of the diaphragm (Edi). The aim was to evaluate patient-ventilator interaction in infants during NAVA as compared with conventional ventilation. METHODS Infants were successively ventilated with NAVA, pressure control ventilation (PCV), and pressure support ventilation (PSV). Edi and ventilator pressure (Pvent) waveforms were compared and their variability was assessed by coefficients of variation. RESULTS Ten patients (mean age 4.3 ± 2.4 mo and weight 5.9 ± 2.2 kg) were studied. In PCV and PSV, 4 ± 4.6% and 6.5 ± 7.7% of the neural efforts failed to trigger the ventilator. This did not occur during NAVA. Trigger delays were shorter with NAVA as compared with PCV and PSV (93 ± 20 ms vs. 193 ± 87 ms and 135 ± 29 ms). During PCV and PSV, the ventilator cycled off before the end of neural inspiration in 12 ± 13% and 21 ± 19% of the breaths (0 ± 0% during NAVA). During PCV and PSV, 24 ± 11% and 25 ± 9% of the neural breath cycle was asynchronous with the ventilator as compared with 11 ± 3% with NAVA. A large variability was observed for Edi in all modes, which was transmitted into Pvent during NAVA (coefficient of variation: 24 ± 8%) and not in PCV (coefficient of variation 2 ± 1%) or PSV (2 ± 2%). CONCLUSION NAVA improves patient-ventilator interaction and delivers adequate ventilation with variable pressure in infants.
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Assessment of patient-ventilator breath contribution during neurally adjusted ventilatory assist. Intensive Care Med 2012; 38:1224-32. [PMID: 22584798 DOI: 10.1007/s00134-012-2588-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 04/17/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE During neurally adjusted ventilatory assist (NAVA), it is difficult to quantify the relative contribution of the patient versus the ventilator to the inspiratory tidal volume (Vt(insp)). To solve this problem, we developed an index, the "patient-ventilator breath contribution" (PVBC), using the inspiratory deflection of the diaphragmatic electrical activity (∆EAdi) and Vt(insp) during assisted and non-assisted breaths. This study evaluated the PVBC index in an experimental setup. METHOD Nine intubated and sedated rabbits were studied during repeated ramp increases of the NAVA level. One breath was non-assisted at each NAVA level. The PVBC index was evaluated during resistive loading and after acute lung injury. PVBC was calculated by relating Vt(insp)/∆EAdi of a non-assisted breath to that of the preceding assisted breath. The PVBC was compared to the relative contribution of esophageal pressure (∆Pes) to transpulmonary pressure deflections (∆P (L,dyn)). RESULTS The relationship between PVBC and ∆Pes/∆P (L,dyn) was slightly curvilinear with an intercept different from zero (y = -1x (2 )+ 1.64x + 0.21) and a determination coefficient (R (2)) of 0.95. Squaring the PVBC values resulted in a near perfect linear relationship (y = 1.02x + 0.05) between PVBC(2) and ∆Pes/∆P (L,dyn) with an R (2) of 0.97. CONCLUSION This study shows that Vt(insp) and EAdi can be used to predict the contribution of the inspiratory muscles versus that of the ventilator during NAVA. If clinically applicable, this could serve to quantify and standardize the adjustment of the level of assist, and hence reduce the risks of excessive ventilatory assist. Further studies are required to evaluate if this method is clinically applicable.
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BARWING J, LINDEN N, AMBOLD M, QUINTEL M, MOERER O. Neurally adjusted ventilatory assist vs. pressure support ventilation in critically ill patients: an observational study. Acta Anaesthesiol Scand 2011; 55:1261-71. [PMID: 22092132 DOI: 10.1111/j.1399-6576.2011.02522.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2011] [Indexed: 01/20/2023]
Abstract
BACKGROUND During neurally adjusted ventilatory assist (NAVA), the inspiratory support is controlled by the patients' respiratory drive influenced by an operator-controlled gain factor (NAVA level). The purpose of our observational study was to transfer patients from conventional pressure support ventilation (PSV) to NAVA safely. We compared two approaches to set the NAVA level and evaluated the effect of NAVA. METHODS We studied mechanically ventilated patients capable of spontaneous breathing. For the change of the ventilator mode, we used a NAVA level calculated to generate a peak inspiratory pressure equal to PSV. We compared this NAVA level with a NAVA level determined by a NAVA level titration. Ventilatory and haemodynamic data were recorded during an observational period of 6 h. RESULTS All 20 patients included in the study could be transferred from PSV to NAVA and completed the observation interval. Setting the NAVA level according to prior PSV settings proved to be a feasible approach, but in 75% of our patients, we modified the NAVA level according to the titration results. Gas exchange and ventilatory mechanics during the observation interval remained stable. CONCLUSIONS The ventilator mode NAVA seems to be well tolerated in a heterogeneous group of critically ill patients. Pre-setting of the NAVA level during PSV can result in an overestimation of the required ventilator support. An additional titration of the NAVA level ads valuable information although difficult to interpret in some cases.
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Affiliation(s)
- J. BARWING
- Department of Anesthesiology, Emergency and Intensive Care Medicine; University of Göttingen Medical School; Göttingen; Germany
| | - N. LINDEN
- Department of Anesthesiology, Emergency and Intensive Care Medicine; University of Göttingen Medical School; Göttingen; Germany
| | - M. AMBOLD
- Department of Anesthesiology, Emergency and Intensive Care Medicine; University of Göttingen Medical School; Göttingen; Germany
| | - M. QUINTEL
- Department of Anesthesiology, Emergency and Intensive Care Medicine; University of Göttingen Medical School; Göttingen; Germany
| | - O. MOERER
- Department of Anesthesiology, Emergency and Intensive Care Medicine; University of Göttingen Medical School; Göttingen; Germany
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Patient-ventilator interaction during pressure support ventilation and neurally adjusted ventilatory assist*. Crit Care Med 2010; 38:518-26. [DOI: 10.1097/ccm.0b013e3181cb0d7b] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Campoccia Jalde F, Almadhoob AR, Beck J, Slutsky AS, Dunn MS, Sinderby C. Neurally adjusted ventilatory assist and pressure support ventilation in small species and the impact of instrumental dead space. Neonatology 2010; 97:279-85. [PMID: 19887857 PMCID: PMC3701441 DOI: 10.1159/000255167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 05/18/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND Neurally adjusted ventilatory assist (NAVA) is a pneumatically-independent mode of mechanical ventilation controlled by diaphragm electrical activity (EAdi), and has not yet been implemented in very small species. OBJECTIVES The aims of the study were to evaluate the feasibility of applying NAVA in very small species and to compare this to pressure support ventilation (PSV) in terms of ventilatory efficiency and breathing pattern, and evaluate the impact of instrumental dead space on breathing pattern during both modes. METHODS Nine healthy rats (mean weight 385 +/- 4 g) were studied while breathing on PSV or NAVA, at baseline or with added dead space. RESULTS A clear difference in breathing pattern between NAVA and PSV was observed during both baseline and dead space, where PSV - despite similar EAdi and tidal volume as during NAVA - caused shortened inspiratory time (p < 0.05) and increased the respiratory rate (p < 0.05). A higher minute ventilation (p < 0.05) in order to reach the same arterial CO(2) was observed. Ineffective inspiratory efforts occurred only during PSV and decreased with the dead space. CONCLUSION This study demonstrates, in a small group of animals, that NAVA can deliver assist in very small species with a higher efficiency than PSV in terms of eliminating CO(2) for a given minute ventilation.
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Affiliation(s)
- Francesca Campoccia Jalde
- Department of Anaesthesiology and Intensive Care, Karolinska Hospital and Institute, Stockholm, Sweden
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Lecomte F, Brander L, Jalde F, Beck J, Qui H, Elie C, Slutsky AS, Brunet F, Sinderby C. Physiological response to increasing levels of neurally adjusted ventilatory assist (NAVA). Respir Physiol Neurobiol 2009; 166:117-24. [DOI: 10.1016/j.resp.2009.02.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 02/21/2009] [Accepted: 02/25/2009] [Indexed: 10/21/2022]
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Brander L, Leong-Poi H, Beck J, Brunet F, Hutchison SJ, Slutsky AS, Sinderby C. Titration and Implementation of Neurally Adjusted Ventilatory Assist in Critically Ill Patients. Chest 2009; 135:695-703. [DOI: 10.1378/chest.08-1747] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Reduction of patient-ventilator asynchrony by reducing tidal volume during pressure-support ventilation. Intensive Care Med 2008; 34:1477-86. [PMID: 18437356 DOI: 10.1007/s00134-008-1121-9] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Accepted: 03/27/2008] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To identify ventilatory setting adjustments that improve patient-ventilator synchrony during pressure-support ventilation in ventilator-dependent patients by reducing ineffective triggering events without decreasing tolerance. DESIGN AND SETTING Prospective physiological study in a 13-bed medical intensive care unit in a university hospital. PATIENTS AND PARTICIPANTS Twelve intubated patients with more than 10% of ineffective breaths while receiving pressure-support ventilation. INTERVENTIONS Flow, airway-pressure, esophageal-pressure, and gastric-pressure signals were used to measure patient inspiratory effort. To decrease ineffective triggering the following ventilator setting adjustments were randomly adjusted: pressure support reduction, insufflation time reduction, and change in end-expiratory pressure. MEASUREMENTS AND RESULTS Reducing pressure support from 20.0 cm H(2)O (IQR 19.5-20) to 13.0 (12.0-14.0) reduced tidal volume [10.2ml /kg predicted body weight (7.2-11.5) to 5.9 (4.9-6.7)] and minimized ineffective triggering events [45% of respiratory efforts (36-52) to 0% (0-7)], completely abolishing ineffective triggering in two-thirds of patients. The ventilator respiratory rate increased due to unmasked wasted efforts, with no changes in patient respiratory rate [26.5 breaths/min (23.1-31.9) vs. 29.4 (24.6-34.5)], patient effort, or arterial PCO(2). Shortening the insufflation time reduced ineffective triggering events and patient effort, while applying positive end-expiratory pressure had no influence on asynchrony. CONCLUSIONS Markedly reducing pressure support or inspiratory duration to reach a tidal volume of about 6 ml/kg predicted body weight eliminated ineffective triggering in two-thirds of patients with weaning difficulties and a high percentage of ineffective efforts without inducing excessive work of breathing or modifying patient respiratory rate.
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Spahija J, Beck J, de Marchie M, Comtois A, Sinderby C. Closed-Loop Control of Respiratory Drive Using Pressure-Support Ventilation. Am J Respir Crit Care Med 2005; 171:1009-14. [PMID: 15665323 DOI: 10.1164/rccm.200407-856oc] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
By using diaphragm electrical activity (multiple-array esophageal electrode) as an index of respiratory drive, and allowing such activity above or below a preset target range to indicate an increased or reduced demand for ventilatory assistance (target drive ventilation), we evaluated whether the level of pressure-support ventilation can be automatically adjusted in response to exercise-induced changes in ventilatory demand. Eleven healthy individuals breathed through a circuit (18 cm H2O/L/second inspiratory resistance at 1 L/second flow; 0.5-1.0 L/second expiratory flow limitation) connected to a modified ventilator. Subjects breathed for 6-minute periods at rest and during 20 and 40 W of bicycle exercise, with and without target drive ventilation (the target was set to 60% of the increase in diaphragm electrical activity observed between rest and 20 W of unassisted exercise). With target drive ventilation during exercise, the level of pressure-support ventilation was automatically increased, reaching 13.3 +/- 4.0 and 20.3 +/- 2.8 cm H2O during 20- and 40-W exercise, respectively, whereas diaphragm electrical activity was reduced to a level within the target range. Both diaphragmatic pressure-time product and end-tidal CO2 were significantly reduced with target drive ventilation at the end of the 20- (p < 0.01) and 40-W (p < 0.001) exercise periods. Minute ventilation was not altered. These results demonstrate that target drive ventilation can automatically adjust pressure-support ventilation, maintaining a constant neural drive and compensating for changes in respiratory demand.
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Affiliation(s)
- Jadranka Spahija
- Research Center, Respiratory Health Research Unit, Sacré-Coeur Hospital of Montreal, Canada H4J 1C5.
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Respiratory Muscle Unloading during Mechanical Ventilation. Intensive Care Med 2003. [DOI: 10.1007/978-1-4757-5548-0_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Brochard L. When ventilator and patient's end of inspiration don't coincide: what's the matter? Am J Respir Crit Care Med 2002; 166:2-3. [PMID: 12091158 DOI: 10.1164/rccm.2205008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Heyer L, Baconnier PF, Eberhard A, Biot L, Viale JP, Perdrix JP, Carry PY. Non-invasive detection of respiratory muscles activity during assisted ventilation. C R Biol 2002; 325:383-91. [PMID: 12161918 DOI: 10.1016/s1631-0691(02)01435-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The instantaneous pressure applied by the respiratory muscles [Pmus(t)] of a patient under ventilatory support may be continuously assessed with the help of a model of the passive respiratory system updated cycle by cycle. Inspiratory activity (IA) is considered present when Pmus goes below a given threshold. In six patients, we compared IA with (i) inspiratory activity (IAref) obtained from esophageal pressure and diaphragmatic EMG and (ii) that (IAvent) detected by the ventilator. In any case, a ventilator support onset coincides with an IA onset but the opposite is not true. IA onset is always later than IAref beginning ((0.21 +/- 0.10 s) and IA end always precedes IAref end (0.46 +/- 0.16 s). These results clearly deteriorate when the model is not updated.
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Affiliation(s)
- Laurent Heyer
- Laboratoire TIMC/IMAG, faculté de médecine de Grenoble, université Joseph-Fourier, 38700 La Tronche, France
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Patroniti N, Foti G, Pesenti A. Assisting Ventilation by Pressure Support: More than a Weaning Tool. Intensive Care Med 2002. [DOI: 10.1007/978-1-4757-5551-0_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Beck J, Gottfried SB, Navalesi P, Skrobik Y, Comtois N, Rossini M, Sinderby C. Electrical activity of the diaphragm during pressure support ventilation in acute respiratory failure. Am J Respir Crit Care Med 2001; 164:419-24. [PMID: 11500343 DOI: 10.1164/ajrccm.164.3.2009018] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We compared crural diaphragm electrical activity (EAdi) with transdiaphragmatic pressure (Pdi) during varying levels of pressure support ventilation (PS) in 13 intubated patients. With changing PS, we found no evidence for changes in neuromechanical coupling of the diaphragm. From lowest to highest PS (2 cm H(2)O +/- 4 to 20 cm H(2)O +/- 7), tidal volume increased from 430 ml +/- 180 to 527 ml +/- 180 (p < 0.001). The inspiratory volume calculated during the period when EAdi increased to its peak did not change from 276 +/- 147 to 277 +/- 162 ml, p = 0.976. Respiratory rate decreased from 23.9 (+/- 7) to 21.3 (+/- 7) breaths/min (p = 0.015). EAdi and Pdi decreased proportionally by adding PS (r = 0.84 and r = 0.90, for mean and peak values, respectively). Mean and peak EAdi decreased (p < 0.001) by 33 +/- 21% (mean +/- SD) and 37 +/- 23% with the addition of 10 cm H(2)O of PS, similar to the decrease in the mean and peak Pdi (p < 0.001) observed (34 +/- 36 and 35 +/- 23%). We also found that ventilator assist continued during the diaphragm deactivation period, a phenomenon that was further exaggerated at higher PS levels. We conclude that EAdi is a valid measurement of neural drive to the diaphragm in acute respiratory failure.
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Affiliation(s)
- J Beck
- Hôpital Ste-Justine, Department of Pediatrics, Montreal, Quebec, Canada.
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Abstract
The ventilatory drive is affected by several factors such as chemosensitivity, basal arterial oxygen or carbon dioxide tension, mechanical impedance, and respiratory muscle dysfunction. Blunted ventilatory drive or a decrease in the perception of dyspnea in bronchial asthma and chronic obstructive pulmonary disease (COPD) could lead to a decrease in the alarm reaction to dangerous situations such as severe airway obstruction, severe hypoxemia, or severe hypercapnia. This could delay management and treatment, causing an increase in the morbidity and mortality of patients with bronchial asthma and COPD. The ventilatory drive to chemical stimuli can be altered by a beta-2-agonist, oxygen administration; and lung volume reduction, and an increased dyspnea sensation may be improved by corticosteroid, chest wall vibration, or lung volume reduction. The ventilatory drive has been found to play a key role in determining the severity of asthma and COPD.
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Affiliation(s)
- W Hida
- First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan
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