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Jiang L, Chen H, Xie J, Liu L, Yang Y. Prognostic value of time-varying dead space estimates in mechanically ventilated patients with acute respiratory distress syndrome. JOURNAL OF INTENSIVE MEDICINE 2024; 4:187-193. [PMID: 38681797 PMCID: PMC11043632 DOI: 10.1016/j.jointm.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 08/09/2023] [Accepted: 08/10/2023] [Indexed: 05/01/2024]
Abstract
Background The dead space fraction (VD/VT) has proven to be a powerful predictor of higher mortality in acute respiratory distress syndrome (ARDS). However, its measurement relies on expired carbon dioxide, limiting its widespread application in clinical practice. Several estimates employing routine variables have been found to be reliable substitutes for direct measurement of VD/VT. In this study, we evaluated the prognostic value of these dead space estimates obtained in the first 7 days following the initiation of ventilation. Methods This retrospective observational study was conducted using data from the Chinese database in intensive care (CDIC). Eligible participants were adult ARDS patients receiving invasive mechanical ventilation while in the intensive care unit between 1st January 2014 and 31st March 2021. We collected data during the first 7 days of ventilation to calculate various dead space estimates, including ventilatory ratio (VR), corrected minute ventilation (V ˙ Ecorr ), VD/VT (Harris-Benedict), VD/VT (Siddiki estimate), and VD/VT (Penn State estimate) longitudinally. A time-dependent Cox model was used to handle these time-varying estimates. Results A total of 392 patients (median age 66 [interquartile range: 55-77] years, median SOFA score 9 [interquartile range: 7-12]) were finally included in our analysis, among whom 132 (33.7%) patients died within 28 days of admission. VR (hazard ratio [HR]=1.04 per 0.1 increase, 95% confidence interval [CI]: 1.01 to 1.06; P=0.013), V ˙ Ecorr (HR=1.08 per 1 increase, 95% CI: 1.04 to 1.12; P < 0.001), VD/VT (Harris-Benedict) (HR=1.25 per 0.1 increase, 95% CI: 1.06 to 1.47; P=0.006), and VD/VT (Penn State estimate) (HR=1.22 per 0.1 increase, 95% CI: 1.04 to 1.44; P=0.017) remained significant after adjustment, while VD/VT (Siddiki estimate) (HR=1.10 per 0.1 increase, 95% CI: 1.00 to 1.20; P=0.058) did not. Given a large number of negative values, VD/VT (Siddiki estimate) and VD/VT (Penn State estimate) were not recommended as reliable substitutes. Long-term exposure to VR >1.3, V ˙ Ecorr >7.53, and VD/VT (Harris-Benedict) >0.59 was independently associated with an increased risk of mortality in ARDS patients. These findings were validated in the fluid and catheter treatment trial (FACTT) database. Conclusions In cases where VD/VT cannot be measured directly, early time-varying estimates of VD/VT such as VR, V ˙ Ecorr , and VD/VT (Harris-Benedict) can be considered for predicting mortality in ARDS patients, offering a rapid bedside application.
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Affiliation(s)
- Lianlian Jiang
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Hui Chen
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
- Department of Critical Care Medicine, The First Affiliated Hospital of Soochow University, Soochow University, Suzhou, Jiangsu, China
| | - Jianfeng Xie
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Ling Liu
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Yi Yang
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
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Fujihara T, Shono A, Katayama N, Nikai T, Shiratsuki Y, Amano Y, Saito Y. Whole lung lavage decreases physiological dead space in patients with pulmonary alveolar proteinosis: two case reports. J Med Case Rep 2023; 17:353. [PMID: 37596611 PMCID: PMC10439532 DOI: 10.1186/s13256-023-04085-8] [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: 01/25/2023] [Accepted: 07/16/2023] [Indexed: 08/20/2023] Open
Abstract
BACKGROUND Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by progressive accumulation of the alveolar surfactant. Whole lung lavage (WLL) using a high volume of warmed saline remains the standard therapy. However, no established bedside monitoring tool can evaluate the physiological effect of WLL in the perioperative period. Indirect calorimetry, which is generally used to measure resting energy expenditure, can detect carbon dioxide (CO2) production and mixed-expired partial pressure of CO2 breath by breath. In this physiological study, we calculated CO2 elimination per breath (VTCO2,br) and Enghoff's dead space using indirect calorimetry and measured the extravascular lung water index to reveal the effect of WLL. CASE PRESENTATION We measured VTCO2,br, Enghoff's dead space, and the extravascular lung water and cardiac indices before and after WLL to assess the reduction in shunt by washing out the surfactant. A total of four WLLs were performed in two PAP patients. The first case involved an Asian 62-year-old man who presented with a 3-month history of dyspnea on exertion. The second case involved an Asian 48-year-old woman with no symptoms. VTCO2,br increased, and the Enghoff's dead space decreased at 12 h following WLL. An increase in the extravascular lung water was detected immediately following WLL, leading to a transient increase in Enghoff's dead space. CONCLUSION WLL can increase efficient alveolar ventilation by washing out the accumulated surfactant. However, the lavage fluid may be absorbed into the lung tissues immediately after WLL and result in an increase in the extravascular lung water.
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Affiliation(s)
- Tatsuya Fujihara
- Division of Emergency and Critical Care Department, Shimane Prefectural Central Hospital, 4-1-1 Himebara, Izumo, Shimane, 693-8555, Japan.
| | - Atsuko Shono
- Department of Intensive Care Medicine, Showa University School of Medicine, Tokyo, Japan
| | - Nozomi Katayama
- Department of Anesthesiology, Faculty of Medicine, Shimane University, Izumo, Japan
| | - Tetsuro Nikai
- Department of Anesthesiology, Faculty of Medicine, Shimane University, Izumo, Japan
| | - Yohei Shiratsuki
- Division of Medical Oncology and Respiratory Medicine Department of Internal Medicine, Faculty of Medicine, Shimane University, Izumo, Japan
| | - Yoshihiro Amano
- Division of Medical Oncology and Respiratory Medicine Department of Internal Medicine, Faculty of Medicine, Shimane University, Izumo, Japan
| | - Yoji Saito
- Department of Anesthesiology, Faculty of Medicine, Shimane University, Izumo, Japan
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Zheng M. Dead space ventilation-related indices: bedside tools to evaluate the ventilation and perfusion relationship in patients with acute respiratory distress syndrome. Crit Care 2023; 27:46. [PMID: 36732812 PMCID: PMC9894747 DOI: 10.1186/s13054-023-04338-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Cumulative evidence has demonstrated that the ventilatory ratio closely correlates with mortality in acute respiratory distress syndrome (ARDS), and a primary feature in coronavirus disease 2019 (COVID-19)-ARDS is increased dead space that has been reported recently. Thus, new attention has been given to this group of dead space ventilation-related indices, such as physiological dead space fraction, ventilatory ratio, and end-tidal-to-arterial PCO2 ratio, which, albeit distinctive, are all global indices with which to assess the relationship between ventilation and perfusion. These parameters have already been applied to positive end expiratory pressure titration, prediction of responses to the prone position and the field of extracorporeal life support for patients suffering from ARDS. Dead space ventilation-related indices remain hampered by several deflects; notwithstanding, for this catastrophic syndrome, they may facilitate better stratifications and identifications of subphenotypes, thereby providing therapy tailored to individual needs.
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Affiliation(s)
- Mingjia Zheng
- Department of Respiratory and Critical Care Medicine, Huzhou Central Hospital, Affiliated Central Hospital Huzhou University, No. 1558, Sanhuan North Road, Wuxing, Huzhou, Zhejiang, People's Republic of China.
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Yueyi J, Jing T, Lianbing G. A structured narrative review of clinical and experimental studies of the use of different positive end-expiratory pressure levels during thoracic surgery. THE CLINICAL RESPIRATORY JOURNAL 2022; 16:717-731. [PMID: 36181340 PMCID: PMC9629996 DOI: 10.1111/crj.13545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 09/03/2022] [Accepted: 09/12/2022] [Indexed: 01/25/2023]
Abstract
OBJECTIVES This study aimed to present a review on the general effects of different positive end-expiratory pressure (PEEP) levels during thoracic surgery by qualitatively categorizing the effects into detrimental, beneficial, and inconclusive. DATA SOURCE Literature search of Pubmed, CNKI, and Wanfang was made to find relative articles about PEEP levels during thoracic surgery. We used the following keywords as one-lung ventilation, PEEP, and thoracic surgery. RESULTS We divide the non-individualized PEEP value into five grades, that is, less than 5, 5, 5-10, 10, and more than 10 cmH2 O, among which 5 cmH2 O is the most commonly used in clinic at present to maintain alveolar dilatation and reduce the shunt fraction and the occurrence of atelectasis, whereas individualized PEEP, adjusted by test titration or imaging method to adapt to patients' personal characteristics, can effectively ameliorate intraoperative oxygenation and obtain optimal pulmonary compliance and better indexes relating to respiratory mechanics. CONCLUSIONS Available data suggest that PEEP might play an important role in one-lung ventilation, the understanding of which will help in exploring a simple and economical method to set the appropriate PEEP level.
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Affiliation(s)
- Jiang Yueyi
- The Affiliated Cancer Hospital of Nanjing Medical UniversityNanjingChina
| | - Tan Jing
- Department of AnesthesiologyJiangsu Cancer HospitalNanjingChina
| | - Gu Lianbing
- The Affiliated Cancer Hospital of Nanjing Medical UniversityNanjingChina,Department of AnesthesiologyJiangsu Cancer HospitalNanjingChina
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Difference between arterial and end-tidal carbon dioxide and adverse events after non-cardiac surgery: a historical cohort study. Can J Anaesth 2021; 69:106-118. [PMID: 34617239 PMCID: PMC8494171 DOI: 10.1007/s12630-021-02118-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 11/18/2022] Open
Abstract
Purpose The difference between arterial and end-tidal partial pressure of carbon dioxide (ΔCO2) is a measure of alveolar dead space, commonly evaluated intraoperatively. Given its relationship to ventilation and perfusion, ΔCO2 may provide prognostic information and guide clinical decisions. We hypothesized that higher ΔCO2 values are associated with occurrence of a composite outcome of re-intubation, postoperative mechanical ventilation, or 30-day mortality in patients undergoing non-cardiac surgery. Methods We conducted a historical cohort study of adult patients undergoing non-cardiac surgery with an arterial line at a single tertiary care medical centre. The composite outcome, identified from electronic health records, was re-intubation, postoperative mechanical ventilation, or 30-day mortality. Student’s t test and Chi-squared test were used for univariable analysis. Logistic regression was used for multivariable analysis of the relationship of ΔCO2 with the composite outcome. Results A total of 19,425 patients were included in the final study population. Univariable analysis showed an association between higher mean (standard deviation [SD]) intraoperative ΔCO2 values and the composite outcome (6.1 [5.3] vs 5.7 [4.5] mm Hg; P = 0.002). After adjusting for baseline subject characteristics, every 5-mm Hg increase in the ΔCO2 was associated with a nearly 20% increased odds of the composite outcome (odds ratio, 1.20; 95% confidence interval, 1.12 to 1.28; P < 0.001). Conclusions In this patient population, increased intraoperative ΔCO2 was associated with an increased odds of the composite outcome of postoperative mechanical ventilation, re-intubation, or 30-day mortality that was independent of its relationship with pre-existing pulmonary disease. Future studies are needed to determine if ΔCO2 can be used to guide patient management and improve patient outcomes.
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Wang J, Zhang J, Liu Y, Shang H, Peng L, Cui Z. Relationship between end-tidal carbon dioxide and arterial carbon dioxide in critically ill patients on mechanical ventilation: A cross-sectional study. Medicine (Baltimore) 2021; 100:e26973. [PMID: 34414969 PMCID: PMC8376328 DOI: 10.1097/md.0000000000026973] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 08/01/2021] [Indexed: 01/04/2023] Open
Abstract
So far, only a few studies have examined and confirmed the correlation between end-expiratory carbon dioxide partial pressure (PETCO2) and arterial carbon dioxide tension (PaCO2) during invasive mechanical ventilation in critically ill patients. This study aimed to observe the correlation between PaCO2 and PETCO2 in patients on invasive mechanical ventilation.This was a cross-sectional study of adult patients on invasive mechanical ventilation enrolled between June 2018 and March 2019. Patients requiring invasive mechanical ventilation underwent one of the following mechanical ventilation modes: assisted/controlled ventilation, synchronized intermittent mandatory ventilation, and spontaneous breathing. Subsequently, the difference and correlation between PETCO2 and PaCO2 were analyzed.A total of 184 patients with 298 pairs of PETCO2-PaCO2 data were included in the analysis. Without distinguishing the ventilator mode, there was significant positive correlation between PETCO2 and PaCO2. In different ventilator modes, the correlation coefficient was 0.81 for synchronized intermittent mandatory ventilation, 0.47 for assisted/controlled ventilation, and 0.55 for spontaneous breathing, respectively. In patients with chronic obstructive pulmonary disease (r = 0.80), multiple trauma (r = 0.64), severe pneumonia (r = 0.60), gastrointestinal surgery (r = 0.57), and cerebrovascular diseases (r = 0.53), PETCO2 and PaCO2 were positively correlated. For oxygenation index <200 mm Hg, correlation coefficient r = 0.69, P < .001; oxygenation index ≥200, r = 0.73, P < .001. Under different oxygenation indexes, there was no statistically significant difference between the 2 correlation coefficients. Among 116 pairs of data with oxygenation index <200 mm Hg, the difference of PaCO2-PETCO2 ≥10 mm Hg was found in 25 pairs (21.55%); in 182 pairs of data with oxygenation index ≥200 mm Hg, the difference of PaCO2-PETCO2 ≥10 mm Hg was found in 26 pairsIn patients on invasive mechanical ventilation, there was a good correlation between PETCO2 and PaCO2 in different ventilator modes, different disease types, and different oxygenation indexes, especially in synchronized intermittent mandatory ventilation mode and chronic obstructive pulmonary disease patients.
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Zuiki M, Kume R, Matsuura A, Mitsuno K, Kitamura K, Kanayama T, Komatsu H. Large difference between Enghoff and Bohr dead space in ventilated infants with hypoxemic respiratory failure. Pediatr Pulmonol 2021; 56:2102-2107. [PMID: 33866691 DOI: 10.1002/ppul.25403] [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: 11/09/2020] [Revised: 03/16/2021] [Accepted: 03/26/2021] [Indexed: 11/06/2022]
Abstract
BACKGROUND Ventilated neonates with hypoxemic respiratory failure (HRF) may show a ventilation-perfusion (V/Q) mismatch. OBJECTIVE To evaluate the difference between the Bohr (Vd, Bohr ) and Enghoff (Vd, Enghoff ) dead spaces in infants by using volumetric capnography based on ventilator graphics and capnograms. METHODS This study enrolled 46 ventilated infants (mean birth weight, 2239 ± 640 g; mean gestational age, 35.5 ± 3.3 weeks). We performed volumetric capnography and calculated Vd, Bohr and Vd, Enghoff when arterial blood sampling was necessary for treatment. According to the oxygenation index (OI) based on the Montreux definition of neonatal acute respiratory distress syndrome, each measurement was classified into the HRF (OI ≥ 4) or control (OI < 4) group. Then, a regression analysis was performed to evaluate the correlation between the OI and the difference between Vd, Enghoff and Vd, Bohr . RESULTS The median Vd, Enghoff /tidal volume (VT ) was significantly higher in the HRF group (0.55 [interquartile range, 0.47-0.68]) than in the control group (0.46 [0.37-0.57]). The HRF group showed a larger difference between Vd, Enghoff /VT and Vd, Bohr /VT than the control group (median, 0.22 [0.15-0.29] vs. 0.10 [0.06-0.14], respectively). Moreover, the regression analysis of the relationship between OI and Vd, Enghoff /VT - Vd, Bohr /VT showed a positive correlation (r = .60, p < .001). CONCLUSION Ventilated neonates with hypoxemic respiratory failure showed a large difference between Vd, Enghoff and Vd, Bohr , possibly reflecting a low V/Q mismatch and right-to-left shunting.
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Affiliation(s)
- Masashi Zuiki
- Department of Pediatrics, National Hospital Organization Maizuru Medical Center, Maizuru, Kyoto, Japan.,Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, Japan
| | - Rika Kume
- Department of Pediatrics, National Hospital Organization Maizuru Medical Center, Maizuru, Kyoto, Japan
| | - Amane Matsuura
- Department of Pediatrics, National Hospital Organization Maizuru Medical Center, Maizuru, Kyoto, Japan
| | - Kohei Mitsuno
- Department of Pediatrics, National Hospital Organization Maizuru Medical Center, Maizuru, Kyoto, Japan
| | - Kazumasa Kitamura
- Department of Pediatrics, National Hospital Organization Maizuru Medical Center, Maizuru, Kyoto, Japan
| | - Takuyo Kanayama
- Department of Pediatrics, National Hospital Organization Maizuru Medical Center, Maizuru, Kyoto, Japan
| | - Hiroshi Komatsu
- Department of Pediatrics, National Hospital Organization Maizuru Medical Center, Maizuru, Kyoto, Japan
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Rocksén D, Arborelius UP, Gustavsson J, Günther M. Severe, transient pulmonary ventilation-perfusion mismatch in the lung after porcine high velocity projectile behind armor blunt trauma. Exp Lung Res 2020; 46:271-282. [DOI: 10.1080/01902148.2020.1797246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- David Rocksén
- Department of Neuroscience, section of Experimental Traumatology, Karolinska Institutet, Stockholm, Sweden
| | - Ulf P. Arborelius
- Department of Neuroscience, section of Experimental Traumatology, Karolinska Institutet, Stockholm, Sweden
| | - Jenny Gustavsson
- Department of Neuroscience, section of Experimental Traumatology, Karolinska Institutet, Stockholm, Sweden
| | - Mattias Günther
- Department of Clinical Science and Education, Section of Anesthesiology and Intensive Care, Karolinska Institutet, Stockholm, Sweden
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Abstract
Volume capnography provides a noninvasive, continuous display of the fractional concentration or partial pressure of carbon dioxide (Pco2) versus exhaled volume. Derived measurements and calculations are influenced by changes in both ventilation and perfusion and are therefore useful for assessing both respiratory and cardiovascular function. This article provides an evidence-based review of several potential uses of volume capnography in the intensive care unit: 1) monitoring the effectiveness of ventilation by using end-tidal Pco2 as a surrogate for arterial Pco2, 2) assessing volume responsiveness, 3) measuring cardiac output, 4) determining prognosis in patients with the acute respiratory distress syndrome, 5) optimizing alveolar recruitment, and 6) excluding pulmonary embolism. Studies performed during the past few decades have clearly shown that volume capnography can provide important prognostic information in patients with acute respiratory distress syndrome and that end-tidal Pco2 should not be used to estimate or even to monitor the direction of change in the arterial Pco2 in mechanically ventilated intensive care unit patients. Unfortunately, few conclusions can be made from studies evaluating other potential applications. Of these, the most promising are the noninvasive measurement of cardiac output and optimization of alveolar recruitment in patients with acute respiratory distress syndrome and in mechanically ventilated, morbidly obese patients.
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Abstract
INTRODUCTION The use of mechanical ventilation is an invaluable tool in caring for critically ill patients. Enhancing our capabilities in mechanical ventilation has been instrumental in the ability to support clinical conditions and diseases which were once associated with high mortality. Areas covered: Within this manuscript, we will look to discuss emerging approaches to improving the care of pediatric patients who require mechanical ventilation. After an extensive literature search, we will provide a brief review of the history and pathophysiology of acute respiratory distress syndrome, an assessment of several ventilator settings, a discussion on assisted ventilation, review of therapy used to rescue in severe respiratory failure, methods of monitoring the effects of mechanical ventilation, and nutrition. Expert opinion: As we have advanced in our care, we are seeing children survive illnesses that would have once claimed their lives. Given this knowledge, we must continue to advance the research in pediatric critical care to understand the means in which we can tailor the therapy to the patient in efforts to efficiently liberate them from mechanical ventilation once their illness has resolved.
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Affiliation(s)
- Duane C Williams
- a Division of Pediatric Critical Care Medicine, Department of Pediatrics , Penn State Hershey Children's Hospital , Hershey , PA , USA
| | - Ira M Cheifetz
- b Division of Pediatric Critical Care Medicine, Department of Pediatrics , Duke Children's Hospital , Durham , NC , USA
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Sinha P, Calfee CS, Beitler JR, Soni N, Ho K, Matthay MA, Kallet RH. Physiologic Analysis and Clinical Performance of the Ventilatory Ratio in Acute Respiratory Distress Syndrome. Am J Respir Crit Care Med 2019; 199:333-341. [PMID: 30211618 DOI: 10.1164/rccm.201804-0692oc] [Citation(s) in RCA: 182] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Pulmonary dead space fraction (Vd/Vt) is an independent predictor of mortality in acute respiratory distress syndrome (ARDS). Yet, it is seldom used in practice. The ventilatory ratio is a simple bedside index that can be calculated using routinely measured respiratory variables and is a measure of impaired ventilation. Ventilatory ratio is defined as [minute ventilation (ml/min) × PaCO2 (mm Hg)]/(predicted body weight × 100 × 37.5). OBJECTIVES To determine the relation of ventilatory ratio with Vd/Vt in ARDS. METHODS First, in a single-center, prospective observational study of ARDS, we tested the association of Vd/Vt with ventilatory ratio. With in-hospital mortality as the primary outcome and ventilator-free days as the secondary outcome, we tested the role of ventilatory ratio as an outcome predictor. The findings from this study were further verified in secondary analyses of two NHLBI ARDS Network randomized controlled trials. MEASUREMENTS AND MAIN RESULTS Ventilatory ratio positively correlated with Vd/Vt. Ordinal groups of ventilatory ratio had significantly higher Vd/Vt. Ventilatory ratio was independently associated with increased risk of mortality after adjusting for PaO2/FiO2, and positive end-expiratory pressure (odds ratio, 1.51; P = 0.024) and after adjusting for Acute Physiologic Assessment and Chronic Health Evaluation II score (odds ratio, 1.59; P = 0.04). These findings were further replicated in secondary analyses of two separate NHLBI randomized controlled trials. CONCLUSIONS Ventilatory ratio correlates well with Vd/Vt in ARDS, and higher values at baseline are associated with increased risk of adverse outcomes. These results are promising for the use of ventilatory ratio as a simple bedside index of impaired ventilation in ARDS.
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Affiliation(s)
- Pratik Sinha
- 1 Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Department of Medicine
| | - Carolyn S Calfee
- 1 Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Department of Medicine.,2 Department of Anesthesia, and.,3 Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California
| | - Jeremy R Beitler
- 4 Division of Pulmonary and Critical Care Medicine, University of California, San Diego, San Diego, California
| | - Neil Soni
- 5 Magill Department of Anaesthesia, Intensive Care Medicine and Pain Management, Chelsea and Westminster Hospital, London, United Kingdom; and
| | - Kelly Ho
- 6 Respiratory Care Services, Department of Anesthesia and Perioperative Care, University of California, San Francisco at Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, California
| | - Michael A Matthay
- 1 Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Department of Medicine.,2 Department of Anesthesia, and.,3 Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California
| | - Richard H Kallet
- 6 Respiratory Care Services, Department of Anesthesia and Perioperative Care, University of California, San Francisco at Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, California
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Araos JD, Lacitignola L, Stripoli T, Grasso S, Crovace A, Staffieri F. Effects of positive end-expiratory pressure alone or an open-lung approach on recruited lung volumes and respiratory mechanics of mechanically ventilated horses. Vet Anaesth Analg 2019; 46:780-788. [PMID: 31477474 DOI: 10.1016/j.vaa.2019.04.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 03/29/2019] [Accepted: 04/24/2019] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To evaluate the effects of positive end-expiratory pressure (PEEP) alone and PEEP preceded by lung recruitment manoeuvre (LRM) on lung volumes and respiratory system mechanics in healthy horses undergoing general anaesthesia. STUDY DESIGN Controlled, prospective clinical study. ANIMALS A group of 15 horses undergoing arthroscopy. METHODS Following anaesthetic induction, initial ventilatory settings were: tidal volume 15 mL kg-1, inspiratory:expiratory ratio 1:2, respiratory rate to maintain end-tidal CO2 between 5.3-6.6 kPa (40-50 mmHg). The following settings were implemented sequentially: zero PEEP (ZEEP); PEEP 10 cmH2O (PEEP); LRM (50 cmH2O for 20 seconds) followed by 10 cmH2O of PEEP (LRM + PEEP). Static compliance (Cst), driving pressure, delta end-expiratory (ΔEELV) and recruited lung volumes (RLV) were obtained 30 minutes after initiating each ventilatory strategy. Data were analyzed with paired t test or analysis of variance followed by Tukey's post hoc test. Data are shown as mean ± standard deviation; p < 0.05 was considered significant. RESULTS PEEP induced ΔEELV of 6.68 ± 3.36 mL kg-1; ΔEELV during LRM + PEEP was 14.28 ± 5.59 mL kg-1 (p < 0.0001). The RLV was greater during the LRM + PEEP phase (12.30 ± 5.85 mL kg-1) than during PEEP (4.47 ± 3.97 mL kg-1; p < 0.0001). The Cst was unchanged from ZEEP to PEEP (0.75 ± 0.21 and 0.85 ± 0.22 mL cmH2O-1 kg-1, respectively, p = 0.36) but increased using LRM + PEEP (1.11 ± 0.25 mL cmH2O-1 kg-1, p = 0.0004). Driving pressure was lower during LRM + PEEP than during PEEP and ZEEP (16 ± 2, 19 ± 2 and 21 ± 4 cmH2O, respectively, p < 0.0001). CONCLUSIONS AND CLINICAL RELEVANCE Unlike PEEP alone, PEEP preceded by LRM increased RLV and Cst and reduced driving pressure in horses under anaesthesia.
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Affiliation(s)
- Joaquin D Araos
- Centre Hospitalier Universitaire Veterinaire, Faculte de Medecine Veterinaire, Universite de Montreal, Québec, Canada
| | - Luca Lacitignola
- Surgery Unit, Section of Veterinary Clinics and Animal Production, Department of Emergency and Organ Transplantation D.E.O.T., "Aldo Moro" University of Bari, Bari, Italy
| | - Tania Stripoli
- Section of Anesthesia and Intensive Care, Department of Emergency and Organ Transplantation (D.E.O.T.), "Aldo Moro" University of Bari, Bari, Italy
| | - Salvatore Grasso
- Section of Anesthesia and Intensive Care, Department of Emergency and Organ Transplantation (D.E.O.T.), "Aldo Moro" University of Bari, Bari, Italy
| | - Antonio Crovace
- Surgery Unit, Section of Veterinary Clinics and Animal Production, Department of Emergency and Organ Transplantation D.E.O.T., "Aldo Moro" University of Bari, Bari, Italy
| | - Francesco Staffieri
- Surgery Unit, Section of Veterinary Clinics and Animal Production, Department of Emergency and Organ Transplantation D.E.O.T., "Aldo Moro" University of Bari, Bari, Italy.
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Gogniat E, Ducrey M, Dianti J, Madorno M, Roux N, Midley A, Raffo J, Giannasi S, San Roman E, Suarez-Sipmann F, Tusman G. Dead space analysis at different levels of positive end-expiratory pressure in acute respiratory distress syndrome patients. J Crit Care 2019; 45:231-238. [PMID: 29754942 DOI: 10.1016/j.jcrc.2018.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 01/03/2018] [Accepted: 01/07/2018] [Indexed: 01/25/2023]
Abstract
PURPOSE To analyze the effects of positive end-expiratory pressure (PEEP) on Bohr's dead space (VDBohr/VT) in patients with acute respiratory distress syndrome (ARDS). MATERIAL AND METHODS Fourteen ARDS patients under lung protective ventilation settings were submitted to 4 different levels of PEEP (0, 6, 10, 16 cmH2O). Respiratory mechanics, hemodynamics and volumetric capnography were recorded at each protocol step. RESULTS Two groups of patients responded differently to PEEP when comparing baseline with 16-PEEP: those in which driving pressure increased > 15% (∆P˃15%, n = 7, p = .016) and those in which the change was ≤15% (∆P≤15%, n = 7, p = .700). VDBohr/VT was higher in ∆P≤15% than in ∆P≤15% patients at baseline ventilation [0.58 (0.49-0.60) vs 0.46 (0.43-0.46) p = .018], at 0-PEEP [0.50 (0.47-0.54) vs 0.41 (0.40-0.43) p = .012], at 6-PEEP [0.55 (0.49-0.57) vs 0.44 (0.42-0.45) p = .008], at 10-PEEP [0.59 (0.51-0.59) vs 0.45 (0.44-0.46) p = .006] and at 16-PEEP [0.61 (0.56-0.65) vs 0.47 (0.45-0.48) p = .001]. We found a good correlation between ∆P and VDBohr/VT only in the ∆P˃15% group (r = 0.74, p < .001). CONCLUSIONS Increases in PEEP result in higher VDBohr/VT only when associated with an increase in driving pressure.
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Affiliation(s)
- Emiliano Gogniat
- Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Marcela Ducrey
- Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - José Dianti
- Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Matías Madorno
- Instituto Tecnológico Buenos Aires (ITBA), Buenos Aires, Argentina
| | - Nicolás Roux
- Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Alejandro Midley
- Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Julio Raffo
- Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Sergio Giannasi
- Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Eduardo San Roman
- Department of Intensive Care Medicine, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Fernando Suarez-Sipmann
- Department of surgical Sciences, Section of Anesthesia and Critical Care, Uppsala University Hospital, Hedenstierna Laboratory, Uppsala, Sweden; CIBERES, Madrid, Spain; Servicio de Medicina Intensiva, Hospital Universitario y Politécnico La Fe, Valencia, Spain
| | - Gerardo Tusman
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina.
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Tolnai J, Fodor GH, Babik B, Dos Santos Rocha A, Bayat S, Peták F, Habre W. Volumetric but Not Time Capnography Detects Ventilation/Perfusion Mismatch in Injured Rabbit Lung. Front Physiol 2018; 9:1805. [PMID: 30618817 PMCID: PMC6299046 DOI: 10.3389/fphys.2018.01805] [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] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/29/2018] [Indexed: 12/31/2022] Open
Abstract
Whereas time capnography (Tcap) is routinely displayed during mechanical ventilation, the volumetric representation (Vcap) is seldom used. We compared the diagnostic value of indices derived from Tcap and Vcap following ventilation to perfusion ratio ( ) mismatch subsequent to experimentally induced acute respiratory distress syndrome (ARDS), and alveolar recruitment by elevating the positive end-expiratory pressure (PEEP). Lung injury was induced by iv lipopolysaccharide, whole lung lavage and injurious ventilation in anesthetized, mechanically ventilated rabbits (n = 26). Mainstream Tcap and Vcap were performed to assess normalized phase 2 (Sn2T, Sn2V) and phase 3 slopes (Sn3T, Sn3V) in the time and volumetric domains. Vcap was also used to estimate Enghoff’s physiological dead space (VDE). Lung oxygenation index (PaO2/FiO2) and intrapulmonary shunt (Qs/Qt) were derived from arterial and central venous blood gas samples. All measurements were made under baseline conditions, and, following lung injury, under moderate (6 cmH2O) and high PEEP levels (9 cmH2O). Lung injury deteriorated the PaO2/FiO2 (baseline vs. injured 466 ± 10.2 [95% confidence interval] vs. 77.3 ± 17.1 mmHg, p < 0.05) and compromised all mechanical parameters significantly, whereas Tcap parameters exhibited contradictory or inconsistent changes. Conversely, Vcap indices exhibited consistent changes and provided excellent diagnostic value in detecting lung-function deterioration subsequent to lung injury [area under the receiver operating characteristic (ROC) curve of 1.0 ± 0.0, 0.87 ± 0.22 and 0.86 ± 0.22 for VDE, Sn3V and Sn3V/Sn2V, respectively]. Elevated PEEP increased PaO2/FiO2 and decreased Qs/Qt, which was reflected only in the Vcap slope ratio (Sn3V/Sn2V, p < 0.05). Our findings demonstrate the limited value of Tcap to detect ventilation to perfusion ratio ( ) mismatch, following severe lung injury. Conversely, indices derived from Vcap proved to be sensitive for detecting lung volume loss and alveolar recruitment. Therefore, promotion of Vcap is of paramount importance as a real-time, non-invasive, bedside monitoring modality to detect the development of and to follow-up the progression of lung injury in a model of ARDS.
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Affiliation(s)
- József Tolnai
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Gergely H Fodor
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology and Intensive Care, University of Geneva, Geneva, Switzerland
| | - Barna Babik
- Department of Anesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary
| | - André Dos Santos Rocha
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology and Intensive Care, University of Geneva, Geneva, Switzerland
| | - Sam Bayat
- EA-7442 RSRM Laboratory, Department of Clinical Physiology, Sleep and Exercise, Grenoble University Hospital, University of Grenoble, Grenoble, France
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Walid Habre
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology and Intensive Care, University of Geneva, Geneva, Switzerland
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15
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Ferluga M, Lucangelo U, Blanch L. Dead space in acute respiratory distress syndrome. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:388. [PMID: 30460262 DOI: 10.21037/atm.2018.09.46] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dead space is the portion of each tidal volume that does not take part in gas exchange and represents a good global index of the efficiency of the lung function. Dead space is not routinely measured in critical care practice, because the difficulties in in interpreting capnograms and the different methods of calculations. Different dead space indices can provide useful information in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) patients, where changes in microvasculature are the main determinants for the increase in dead space and consequently a worsening of the outcome. Lung recruitment is a dynamic process that combines recruitment manoeuvres (RMs) with positive end expiratory pressure (PEEP) and low Vt to recruit collapsed alveoli. Dead space guided recruitment allows avoiding regional overdistension or reduction in cardiac output in critical care patients with ALI or ARDS. Different patterns of ventilation affect also CO2 elimination; in fact, end-inspiratory pause prolongation reduces dead space, increasing respiratory system compliance; plateau pressure and consequently driving pressure increase accordingly. Dead space measurement is a reliable method that provides important clinical and prognostic information. Different capnographic indices can be useful to evaluate therapeutic interventions or setting mechanical ventilation.
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Affiliation(s)
- Massimo Ferluga
- Emergency and Urgency Department, Cattinara Hospital, Trieste University, Trieste, Italy
| | - Umberto Lucangelo
- Emergency and Urgency Department, Cattinara Hospital, Trieste University, Trieste, Italy
| | - Lluis Blanch
- Critical Care Department, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de Barcelona, Sabadell, Spain
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16
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Blankman P, Shono A, Hermans BJM, Wesselius T, Hasan D, Gommers D. Detection of optimal PEEP for equal distribution of tidal volume by volumetric capnography and electrical impedance tomography during decreasing levels of PEEP in post cardiac-surgery patients. Br J Anaesth 2018; 116:862-9. [PMID: 27199318 PMCID: PMC4872863 DOI: 10.1093/bja/aew116] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2016] [Indexed: 01/26/2023] Open
Abstract
Background Homogeneous ventilation is important for prevention of ventilator-induced lung injury. Electrical impedance tomography (EIT) has been used to identify optimal PEEP by detection of homogenous ventilation in non-dependent and dependent lung regions. We aimed to compare the ability of volumetric capnography and EIT in detecting homogenous ventilation between these lung regions. Methods Fifteen mechanically-ventilated patients after cardiac surgery were studied. Ventilator settings were adjusted to volume-controlled mode with a fixed tidal volume (Vt) of 6–8 ml kg−1 predicted body weight. Different PEEP levels were applied (14 to 0 cm H2O, in steps of 2 cm H2O) and blood gases, Vcap and EIT were measured. Results Tidal impedance variation of the non-dependent region was highest at 6 cm H2O PEEP, and decreased significantly at 14 cm H2O PEEP indicating decrease in the fraction of Vt in this region. At 12 cm H2O PEEP, homogenous ventilation was seen between both lung regions. Bohr and Enghoff dead space calculations decreased from a PEEP of 10 cm H2O. Alveolar dead space divided by alveolar Vt decreased at PEEP levels ≤6 cm H2O. The normalized slope of phase III significantly changed at PEEP levels ≤4 cm H2O. Airway dead space was higher at higher PEEP levels and decreased at the lower PEEP levels. Conclusions In postoperative cardiac patients, calculated dead space agreed well with EIT to detect the optimal PEEP for an equal distribution of inspired volume, amongst non-dependent and dependent lung regions. Airway dead space reduces at decreasing PEEP levels.
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Affiliation(s)
- P Blankman
- Department of Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands
| | - A Shono
- Department of Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands
| | - B J M Hermans
- Institute for Biomedical Technology & Technical Medicine, University of Twente, Enschede, The Netherlands
| | - T Wesselius
- Institute for Biomedical Technology & Technical Medicine, University of Twente, Enschede, The Netherlands
| | - D Hasan
- Department of Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands Institute for Immunotherapy, Duderstadt, Germany
| | - D Gommers
- Department of Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands
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17
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Balogh AL, Petak F, Fodor GH, Tolnai J, Csorba Z, Babik B. Capnogram slope and ventilation dead space parameters: comparison of mainstream and sidestream techniques. Br J Anaesth 2018; 117:109-17. [PMID: 27317710 DOI: 10.1093/bja/aew127] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2016] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Capnography may provide useful non-invasive bedside information concerning heterogeneity in lung ventilation, ventilation-perfusion mismatching and metabolic status. Although the capnogram may be recorded by mainstream and sidestream techniques, the capnogram indices furnished by these approaches have not previously been compared systematically. METHODS Simultaneous mainstream and sidestream time and volumetric capnography was performed in anaesthetized, mechanically ventilated patients undergoing elective heart surgery. Time capnography was used to assess the phase II (SII,T) and III slopes (SIII,T). The volumetric method was applied to estimate phase II (SII,V) and III slopes (SIII,V), together with the dead space values according to the Fowler (VDF), Bohr (VDB), and Enghoff (VDE) methods and the volume of CO2 eliminated per breath ([Formula: see text]). The partial pressure of end-tidal CO2 ([Formula: see text]) was registered. RESULTS Excellent correlation and good agreement were observed in SIII,T measured by the mainstream and sidestream techniques [ratio=1.05 (sem 0.16), R(2)=0.92, P<0.0001]. Although the sidestream technique significantly underestimated [Formula: see text] and overestimated SIII,V [1.32 (0.28), R(2)=0.93, P<0.0001], VDF, VDB, and VDE, the agreement between the mainstream and sidestream techniques in the difference between VDE and VDB, reflecting the intrapulmonary shunt, was excellent [0.97 (0.004), R(2)=0.92, P<0.0001]. The [Formula: see text] exhibited good correlation and mild differences between the mainstream and sidestream approaches [0.025 (0.005) kPa]. CONCLUSIONS Sidestream capnography provides adequate quantitative bedside information about uneven alveolar emptying and ventilation-perfusion mismatching, because it allows reliable assessments of the phase III slope, [Formula: see text] and intrapulmonary shunt. Reliable measurement of volumetric parameters (phase II slope, dead spaces, and eliminated CO2 volumes) requires the application of a mainstream device.
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Affiliation(s)
- A L Balogh
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis u. H-6725, Szeged, Hungary Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, H-6720, Szeged, Hungary
| | - F Petak
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, H-6720, Szeged, Hungary
| | - G H Fodor
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, H-6720, Szeged, Hungary
| | - J Tolnai
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, H-6720, Szeged, Hungary
| | - Z Csorba
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis u. H-6725, Szeged, Hungary
| | - B Babik
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis u. H-6725, Szeged, Hungary
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18
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Mosing M, Böhm SH, Rasis A, Hoosgood G, Auer U, Tusman G, Bettschart-Wolfensberger R, Schramel JP. Physiologic Factors Influencing the Arterial-To-End-Tidal CO 2 Difference and the Alveolar Dead Space Fraction in Spontaneously Breathing Anesthetised Horses. Front Vet Sci 2018; 5:58. [PMID: 29644221 PMCID: PMC5882784 DOI: 10.3389/fvets.2018.00058] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/12/2018] [Indexed: 01/21/2023] Open
Abstract
The arterial to end-tidal CO2 difference (P(a-ET)CO2) and alveolar dead space fraction (VDalvfrac = P(a-ET)CO2/PaCO2), are used to estimate Enghoff's "pulmonary dead space" (V/QEng), a factor which is also influenced by venous admixture and other pulmonary perfusion abnormalities and thus is not just a measure of dead space as the name suggests. The aim of this experimental study was to evaluate which factors influence these CO2 indices in anesthetized spontaneously breathing horses. Six healthy adult horses were anesthetized in dorsal recumbency breathing spontaneously for 3 h. Data to calculate the CO2 indices (response variables) and dead space variables were measured every 30 min. Bohr's physiological and alveolar dead space variables, cardiac output (CO), mean pulmonary pressure (MPP), venous admixture [Formula: see text], airway dead space, tidal volume, oxygen consumption, and slope III of the volumetric capnogram were evaluated (explanatory variables). Univariate Pearson correlation was first explored for both CO2 indices before V/QEng and the explanatory variables with rho were reported. Multiple linear regression analysis was performed on P(a-ET)CO2 and VDalvfrac assessing which explanatory variables best explained the variance in each response. The simplest, best-fit model was selected based on the maximum adjusted R2 and smallest Mallow's p (Cp). The R2 of the selected model, representing how much of the variance in the response could be explained by the selected variables, was reported. The highest correlation was found with the alveolar part of V/QEng to alveolar tidal volume ratio for both, P(a-ET)CO2 (r = 0.899) and VDalvfrac (r = 0.938). Venous admixture and CO best explained P(a-ET)CO2 (R2 = 0.752; Cp = 4.372) and VDalvfrac (R2 = 0.711; Cp = 9.915). Adding MPP (P(a-ET)CO2) and airway dead space (VDalvfrac) to the models improved them only marginally. No "real" dead space variables from Bohr's equation contributed to the explanation of the variance of the two CO2 indices. P(a-ET)CO2 and VDalvfrac were closely associated with the alveolar part of V/QEng and as such, were also influenced by variables representing a dysfunctional pulmonary perfusion. Neither P(a-ET)CO2 nor VDalvfrac should be considered pulmonary dead space, but used as global indices of V/Q mismatching under the described conditions.
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Affiliation(s)
- Martina Mosing
- College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Stephan H Böhm
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
| | - Anthea Rasis
- College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Giselle Hoosgood
- College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Ulrike Auer
- Anaesthesiology and Perioperative Intensive Care Medicine, Veterinary University Vienna, Vienna, Austria
| | - Gerardo Tusman
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina
| | | | - Johannes P Schramel
- Anaesthesiology and Perioperative Intensive Care Medicine, Veterinary University Vienna, Vienna, Austria
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19
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Kacmarek RM, Villar J, Berra L. Exhaled CO 2, a guide to ARDS management during lung-protective ventilation? J Crit Care 2018; 45:229-230. [PMID: 29550109 PMCID: PMC9170239 DOI: 10.1016/j.jcrc.2018.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 03/05/2018] [Indexed: 11/26/2022]
Affiliation(s)
- Robert M Kacmarek
- Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
| | - Jesús Villar
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain; Multidisciplinary Organ Dysfunction Evaluation Research Network, Research Unit, Hospital Universitario Dr. Negrín, Las Palmas de Gran Canaria, Spain.
| | - Lorenzo Berra
- Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
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20
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Nieman GF, Satalin J, Andrews P, Aiash H, Habashi NM, Gatto LA. Personalizing mechanical ventilation according to physiologic parameters to stabilize alveoli and minimize ventilator induced lung injury (VILI). Intensive Care Med Exp 2017; 5:8. [PMID: 28150228 PMCID: PMC5289131 DOI: 10.1186/s40635-017-0121-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 01/26/2017] [Indexed: 12/15/2022] Open
Abstract
It has been shown that mechanical ventilation in patients with, or at high-risk for, the development of acute respiratory distress syndrome (ARDS) can be a double-edged sword. If the mechanical breath is improperly set, it can amplify the lung injury associated with ARDS, causing a secondary ventilator-induced lung injury (VILI). Conversely, the mechanical breath can be adjusted to minimize VILI, which can reduce ARDS mortality. The current standard of care ventilation strategy to minimize VILI attempts to reduce alveolar over-distension and recruitment-derecruitment (R/D) by lowering tidal volume (Vt) to 6 cc/kg combined with adjusting positive-end expiratory pressure (PEEP) based on a sliding scale directed by changes in oxygenation. Thus, Vt is often but not always set as a "one-size-fits-all" approach and although PEEP is often set arbitrarily at 5 cmH2O, it may be personalized according to changes in a physiologic parameter, most often to oxygenation. However, there is evidence that oxygenation as a method to optimize PEEP is not congruent with the PEEP levels necessary to maintain an open and stable lung. Thus, optimal PEEP might not be personalized to the lung pathology of an individual patient using oxygenation as the physiologic feedback system. Multiple methods of personalizing PEEP have been tested and include dead space, lung compliance, lung stress and strain, ventilation patterns using computed tomography (CT) or electrical impedance tomography (EIT), inflection points on the pressure/volume curve (P/V), and the slope of the expiratory flow curve using airway pressure release ventilation (APRV). Although many studies have shown that personalizing PEEP is possible, there is no consensus as to the optimal technique. This review will assess various methods used to personalize PEEP, directed by physiologic parameters, necessary to adaptively adjust ventilator settings with progressive changes in lung pathophysiology.
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Affiliation(s)
- Gary F. Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY USA
| | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY USA
- Cardiopulmonary Critical Care Lab, Department of Surgery, Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210 USA
| | | | - Hani Aiash
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY USA
| | - Nader M. Habashi
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland, Baltimore, MD USA
| | - Louis A. Gatto
- Biological Sciences Department, Biological Sciences Department, SUNY Cortland, Cortland, NY USA
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21
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Nardi N, Mortamet G, Ducharme-Crevier L, Emeriaud G, Jouvet P. Recent Advances in Pediatric Ventilatory Assistance. F1000Res 2017; 6:290. [PMID: 28413621 PMCID: PMC5365224 DOI: 10.12688/f1000research.10408.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/16/2017] [Indexed: 01/17/2023] Open
Abstract
In this review on respiratory assistance, we aim to discuss the following recent advances: the optimization and customization of mechanical ventilation, the use of high-frequency oscillatory ventilation, and the role of noninvasive ventilation. The prevention of ventilator-induced lung injury and diaphragmatic dysfunction is now a key aspect in the management of mechanical ventilation, since these complications may lead to higher mortality and prolonged length of stay in intensive care units. Different physiological measurements, such as esophageal pressure, electrical activity of the diaphragm, and volumetric capnography, may be useful objective tools to help guide ventilator assistance. Companies that design medical devices including ventilators and respiratory monitoring platforms play a key role in knowledge application. The creation of a ventilation consortium that includes companies, clinicians, researchers, and stakeholders could be a solution to promote much-needed device development and knowledge implementation.
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Affiliation(s)
- Nicolas Nardi
- Pediatric Intensive Care Unit, CHU Sainte-Justine, University of Montreal, Montreal, Quebec, Canada
| | - Guillaume Mortamet
- Pediatric Intensive Care Unit, CHU Sainte-Justine, University of Montreal, Montreal, Quebec, Canada
| | | | - Guillaume Emeriaud
- Pediatric Intensive Care Unit, CHU Sainte-Justine, University of Montreal, Montreal, Quebec, Canada
| | - Philippe Jouvet
- Pediatric Intensive Care Unit, CHU Sainte-Justine, University of Montreal, Montreal, Quebec, Canada
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22
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Bian W, Chen W, Chao Y, Wang L, Li L, Guan J, Zang X, Zhen J, Sheng B, Zhu X. Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model. Exp Ther Med 2017; 13:1572-1577. [PMID: 28413511 DOI: 10.3892/etm.2017.4117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/05/2016] [Indexed: 11/05/2022] Open
Abstract
This study aimed to apply the dead space fraction [ratio of dead space to tidal volume (VD/VT)] to titrate the optimal positive end-expiratory pressure (PEEP) in a swine model of acute respiratory distress syndrome (ARDS). Twelve swine models of ARDS were constructed. A lung recruitment maneuver was then conducted and the PEEP was set at 20 cm H2O. The PEEP was reduced by 2 cm H2O every 10 min until 0 cm H2O was reached, and VD/VT was measured after each decrement step. VD/VT was measured using single-breath analysis of CO2, and calculated from arterial CO2 partial pressure (PaCO2) and mixed expired CO2 (PeCO2) using the following formula: VD/VT = (PaCO2 - PeCO2)/PaCO2. The optimal PEEP was identified by the lowest VD/VT method. Respiration and hemodynamic parameters were recorded during the periods of pre-injury and injury, and at 4 and 2 cm H2O below and above the optimal PEEP (Po). The optimal PEEP in this study was found to be 13.25±1.36 cm H2O. During the Po period, VD/VT decreased to a lower value (0.44±0.08) compared with that during the injury period (0.68±0.10) (P<0.05), while the intrapulmonary shunt fraction reached its lowest value. In addition, a significant change of dynamic tidal respiratory compliance and oxygenation index was induced by PEEP titration. These results indicate that minimal VD/VT can be used for PEEP titration in ARDS.
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Affiliation(s)
- Weishuai Bian
- Department of Critical Care Medicine, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, P.R. China
| | - Wei Chen
- Department of Critical Care Medicine, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, P.R. China
| | - Yangong Chao
- Department of Critical Care Medicine, The First Affiliated Hospital, Tsing Hua University, Beijing 100016, P.R. China
| | - Lan Wang
- Department of Critical Care Medicine, Dongzhimen Chinese Medical Hospital, Beijing Chinese-Medical University, Beijing 100700, P.R. China
| | - Liming Li
- Department of Critical Care Medicine, The First Affiliated Hospital, Tsing Hua University, Beijing 100016, P.R. China
| | - Jian Guan
- Department of Critical Care Medicine, The First Affiliated Hospital, Tsing Hua University, Beijing 100016, P.R. China
| | - Xuefeng Zang
- Department of Critical Care Medicine, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, P.R. China
| | - Jie Zhen
- Department of Critical Care Medicine, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, P.R. China
| | - Bo Sheng
- Department of Critical Care Medicine, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, P.R. China
| | - Xi Zhu
- Department of Critical Care Medicine, Third Hospital, Peking University, Beijing 100083, P.R. China
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23
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Blanch L, López-Aguilar J, Lucangelo U. Dead space in acute respiratory distress syndrome: more than a feeling! CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2016; 20:214. [PMID: 27473750 PMCID: PMC4967311 DOI: 10.1186/s13054-016-1381-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Lluis Blanch
- Critical Care Center, Hospital de Sabadell, Corporació Sanitària Universitària ParcTaulí, Universitat Autònoma de Barcelona, c. ParcTaulí 1, 08208, Sabadell, Spain. .,CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
| | - Josefina López-Aguilar
- Critical Care Center, Hospital de Sabadell, Corporació Sanitària Universitària ParcTaulí, Universitat Autònoma de Barcelona, c. ParcTaulí 1, 08208, Sabadell, Spain.,CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Umberto Lucangelo
- Department of Perioperative Medicine, Intensive Care and Emergency, Cattinara Hospital, Trieste University, Trieste, Italy
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Verscheure S, Massion PB, Verschuren F, Damas P, Magder S. Volumetric capnography: lessons from the past and current clinical applications. Crit Care 2016; 20:184. [PMID: 27334879 PMCID: PMC4918076 DOI: 10.1186/s13054-016-1377-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dead space is an important component of ventilation–perfusion abnormalities. Measurement of dead space has diagnostic, prognostic and therapeutic applications. In the intensive care unit (ICU) dead space measurement can be used to guide therapy for patients with acute respiratory distress syndrome (ARDS); in the emergency department it can guide thrombolytic therapy for pulmonary embolism; in peri-operative patients it can indicate the success of recruitment maneuvers. A newly available technique called volumetric capnography (Vcap) allows measurement of physiological and alveolar dead space on a regular basis at the bedside. We discuss the components of dead space, explain important differences between the Bohr and Enghoff approaches, discuss the clinical significance of arterial to end-tidal CO2 gradient and finally summarize potential clinical indications for Vcap measurements in the emergency room, operating room and ICU.
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Affiliation(s)
- Sara Verscheure
- Department of Critical Care Medicine, University of McGill, Montreal, Quebec, Canada.,Department of General Intensive Care, University Hospital of Liege, Liege, Belgium
| | - Paul B Massion
- Department of General Intensive Care, University Hospital of Liege, Liege, Belgium
| | - Franck Verschuren
- Department of Emergency Medicine, Cliniques universitaire Saint-Luc, Université Catholique de Louvain, Brussels, Belgium
| | - Pierre Damas
- Department of General Intensive Care, University Hospital of Liege, Liege, Belgium
| | - Sheldon Magder
- Department of Critical Care Medicine, University of McGill, Montreal, Quebec, Canada.
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Dead Space and Mortality: Physiology Is Still Relevant. Crit Care Med 2016; 43:2516-7. [PMID: 26468708 DOI: 10.1097/ccm.0000000000001324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
OBJECTIVE Elevated dead space has been consistently associated with increased mortality in adults with respiratory failure. In children, the evidence for this association is more limited. We sought to investigate the association between dead space and mortality in mechanically ventilated children. DESIGN Single-center retrospective review. SETTING Tertiary care pediatric critical care unit. PATIENTS Seven hundred twelve mechanically ventilated children with an arterial catheter. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The end-tidal alveolar dead space fraction ((PaCO2-PETCO2)/PaCO2), a dead space marker, was calculated with each arterial blood gas. The initial end-tidal alveolar dead space fraction (first arterial blood gas after intubation) (per 0.1 unit increase: odds ratio, 1.59; 95% CI, 1.40-1.81) and day 1 mean end-tidal alveolar dead space fraction (odds ratio, 1.95; 95% CI, 1.66-2.30) were associated with mortality. The relationship between both initial and day 1 mean end-tidal alveolar dead space fraction and mortality held in multivariate modeling after controlling for any of the following individually: PaO2/FIO2, oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III (all p<0.01), although end-tidal alveolar dead space fraction was no longer significant after controlling for the combination of oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III. In 217 children with acute hypoxemic respiratory failure, initial end-tidal alveolar dead space fraction (per 0.1 unit increase odds ratio, 1.38; 95% CI, 1.14-1.67) and day 1 mean end-tidal alveolar dead space fraction (per 0.1 unit increase odds ratio, 1.60; 95% CI, 1.27-2.0) were associated with mortality. Day 1 mean end-tidal alveolar dead space fraction remained associated with mortality after controlling individually for any of the following in multivariate models: PaO2/FIO2, oxygenation index, and 24-hour maximal inotrope score (p≤0.02), although end-tidal alveolar dead space fraction was no longer significant after controlling for the combination of oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III. CONCLUSIONS Increased dead space is associated with higher mortality in critically ill children, although it is no longer independently associated with mortality after controlling for severity of oxygenation defect, inotrope use, and severity of illness. However, because end-tidal alveolar dead space fraction is easy to calculate at the bedside, it may be useful for risk stratification and severity-of-illness scores.
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Nassar BS, Schmidt GA. Capnography During Critical Illness. Chest 2016; 149:576-585. [DOI: 10.1378/chest.15-1369] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 09/15/2015] [Accepted: 09/16/2015] [Indexed: 11/01/2022] Open
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Abstract
PURPOSE OF REVIEW To provide an overview on most recent knowledge on methods currently available for monitoring of recruitment maneuvers at the bedside. RECENT FINDINGS The effects of recruitment maneuvers on clinical outcomes in patients with moderate to severe acute respiratory distress syndrome and in patients with healthy lungs undergoing major surgery were recently assessed. Despite being part of a multifaceted approach of protective ventilation, recruitment maneuvers are supposed to decrease mortality and improve postoperative outcomes. However, the role of recruitment maneuver remains controversial in routine practice owing to concerns regarding complications, especially its effects on hemodynamics. In addition, although recruitment maneuvers are being increasingly used, there remains a great deal of uncertainty regarding the precise way to evaluate the effect of recruitment.An effective recruitment maneuver is expected to reinflate nonaerated lung units. End-expiratory lung volume, compliance, dead space, volumetric capnography, and bedside imaging techniques such as lung ultrasound and electrical impedance tomography have all different strengths and weaknesses. A multimodal and multiparametric approach could be a valuable option for bedside monitoring of recruitment maneuvers both in the ICU and in the operative room. SUMMARY Several methods offer evaluation of lung recruitability and allow the monitoring of positive and negative effects of recruitment maneuvers. More than the type of method used, a multifaceted approach of monitoring of recruitment maneuvers should be regarded.
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Abstract
PURPOSE OF REVIEW Describe the importance of monitoring dead space during thoracic surgery, specifically during one-lung ventilation. RECENT FINDINGS The concept of dead space has gained renewed interest among anesthesiologists ever since breath-by-breath measurement by volumetric capnography became available. Monitoring dead space during thoracic surgery assesses the ventilatory deficiencies related to increases in instrumental, airway and/or alveolar dead space, when ventilating patients with positive pressure and double-lumen tubes. Another interesting use of such monitoring is to detect ventilator-induced lung injury due to tidal overdistension. This type of injury threatens the fragile lungs especially during one-lung ventilation and can clinically be recognized as an increase in airway and alveolar dead space above normal values. To date, lung protective ventilation is based on the use of low tidal volumes and airway pressures to decrease overdistension. It has been shown to reduce the incidence of postoperative pulmonary complications after thoracic surgeries. However, such a ventilatory strategy impairs ventilation and induces hypercapnia due to increases in dead space. Therefore, continuous assessment of dead space is helpful in guiding ventilation and avoiding overdistension while maintaining the elimination of CO(2) during thoracic surgery sufficiently high. SUMMARY Monitoring dead space helps anesthesiologists monitor the status of the lung and find appropriate ventilatory settings during thoracic surgeries.
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Estimating dead-space fraction for secondary analyses of acute respiratory distress syndrome clinical trials. Crit Care Med 2015; 43:1026-35. [PMID: 25738857 DOI: 10.1097/ccm.0000000000000921] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Pulmonary dead-space fraction is one of few lung-specific independent predictors of mortality from acute respiratory distress syndrome. However, it is not measured routinely in clinical trials and thus altogether ignored in secondary analyses that shape future research directions and clinical practice. This study sought to validate an estimate of dead-space fraction for use in secondary analyses of clinical trials. DESIGN Analysis of patient-level data pooled from acute respiratory distress syndrome clinical trials. Four approaches to estimate dead-space fraction were evaluated: three required estimating metabolic rate; one estimated dead-space fraction directly. SETTING U.S. academic teaching hospitals. PATIENTS Data from 210 patients across three clinical trials were used to compare performance of estimating equations with measured dead-space fraction. A second cohort of 3,135 patients from six clinical trials without measured dead-space fraction was used to confirm whether estimates independently predicted mortality. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Dead-space fraction estimated using the unadjusted Harris-Benedict equation for energy expenditure was unbiased (mean ± SD Harris-Benedict, 0.59 ± 0.13; measured, 0.60 ± 0.12). This estimate predicted measured dead-space fraction to within ±0.10 in 70% of patients and ±0.20 in 95% of patients. Measured dead-space fraction independently predicted mortality (odds ratio, 1.36 per 0.05 increase in dead-space fraction; 95% CI, 1.10-1.68; p < 0.01). The Harris-Benedict estimate closely approximated this association with mortality in the same cohort (odds ratio, 1.55; 95% CI, 1.21-1.98; p < 0.01) and remained independently predictive of death in the larger Acute Respiratory Distress Syndrome Network cohort. Other estimates predicted measured dead-space fraction or its association with mortality less well. CONCLUSIONS Dead-space fraction should be measured in future acute respiratory distress syndrome clinical trials to facilitate incorporation into secondary analyses. For analyses where dead-space fraction was not measured, the Harris-Benedict estimate can be used to estimate dead-space fraction and adjust for its association with mortality.
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Abstract
PURPOSE OF REVIEW Volumetric capnography (VCap) measures the kinetics of carbon dioxide (CO2) elimination on a breath-by-breath basis. A volumetric capnogram contains extensive physiological information about metabolic production, circulatory transport and CO2 elimination within the lungs. VCap is also the best clinical tool to measure dead spaces allowing a detailed analysis of the functional components of each tidal volume, thereby providing clinically useful hints about the lung's efficiency of gas exchange. Difficulties in its bedside measurement, oversimplifications of its interpretation along with prevailing misconceptions regarding dead space analysis have, however, limited its adoption as a routine tool for monitoring mechanically ventilated patients. RECENT FINDINGS Improvements in CO2 measuring technologies and more advanced algorithms for faster and more accurate analysis of volumetric capnograms have increased our physiological understanding and thus the clinical usefulness of VCap. The recently validated VCap-based method for estimating alveolar partial pressure of CO2 provided a breakthrough for a fully noninvasive breath-by-breath measurement of physiological dead space. SUMMARY Recent advances in VCap and our improved understanding of its clinical implications may help in overcoming the known limitations and reluctances to include expired CO2 kinetics and dead space analysis in routine bedside monitoring. It is about time to start using this powerful monitoring tool to support decision making in the intensive care environment.
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YUAN YUEYANG, YANG CHONGCHANG, LI ZHE, CAO ZHIXIN, ZHANG SIMON, SUN JASON. OSCILLATORY FLOW OF HFV DISTRIBUTED IN LEFT AND RIGHT LUNGS: A MODEL-BASED EXPERIMENT AND INVESTIGATION. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414400156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The human respiratory system is not entirely symmetric, and regional respiratory diseases can further enlarge this difference in most cases. Therefore, the lungs perform differently. This paper explored the possibilities of suppressing and enhancing the performance of a diseased lung with different high-frequency ventilation (HFV) frequencies by experimenting, as well as modeling, the oscillatory airflow distribution between the left and right lungs. The experimental setup mainly consisted of a physical respiratory model, a signal acquisition device, and a high-frequency oscillation ventilator. This ventilator outputs a positive sinusoidal air-pressure during inspiration. On these bases, a series of experiments were also conducted with different compliances and resistances in the left and the right lungs. The experiments demonstrated that the oscillatory flow distribution is primarily correlated with the oscillation frequency and the regional lung compliance.
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Affiliation(s)
- YUEYANG YUAN
- College of Mechanical Engineering, Donghua University, Shanghai 210620, P. R. China
| | - CHONGCHANG YANG
- College of Mechanical Engineering, Donghua University, Shanghai 210620, P. R. China
| | - ZHE LI
- Mechanical Engineering Department, Stanford University, 450 Serra Mall, Stanford 94305, California, USA
| | - ZHIXIN CAO
- Department of Respiratory Disease, Beijing Institute of Respiratory Disease, Beijing ChaoYang Hospital, Beijing 100043, P. R. China
| | - SIMON ZHANG
- The Department of Research and Design, Curative Medical Technology Inc, Suzhou 215163, P. R. China
| | - JASON SUN
- The Department of Research and Design, Curative Medical Technology Inc, Suzhou 215163, P. R. China
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Petersson J, Glenny RW. Gas exchange and ventilation-perfusion relationships in the lung. Eur Respir J 2014; 44:1023-41. [PMID: 25063240 DOI: 10.1183/09031936.00037014] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This review provides an overview of the relationship between ventilation/perfusion ratios and gas exchange in the lung, emphasising basic concepts and relating them to clinical scenarios. For each gas exchanging unit, the alveolar and effluent blood partial pressures of oxygen and carbon dioxide (PO2 and PCO2) are determined by the ratio of alveolar ventilation to blood flow (V'A/Q') for each unit. Shunt and low V'A/Q' regions are two examples of V'A/Q' mismatch and are the most frequent causes of hypoxaemia. Diffusion limitation, hypoventilation and low inspired PO2 cause hypoxaemia, even in the absence of V'A/Q' mismatch. In contrast to other causes, hypoxaemia due to shunt responds poorly to supplemental oxygen. Gas exchanging units with little or no blood flow (high V'A/Q' regions) result in alveolar dead space and increased wasted ventilation, i.e. less efficient carbon dioxide removal. Because of the respiratory drive to maintain a normal arterial PCO2, the most frequent result of wasted ventilation is increased minute ventilation and work of breathing, not hypercapnia. Calculations of alveolar-arterial oxygen tension difference, venous admixture and wasted ventilation provide quantitative estimates of the effect of V'A/Q' mismatch on gas exchange. The types of V'A/Q' mismatch causing impaired gas exchange vary characteristically with different lung diseases.
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Affiliation(s)
- Johan Petersson
- Section of Anaesthesiology and Intensive Care Medicine, Dept of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden Dept of Anaesthesiology, Surgical Services and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
| | - Robb W Glenny
- Dept of Medicine, Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, WA, USA Dept of Physiology and Biophysics, University of Washington, Seattle, WA, USA
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Blankman P, Hasan D, Erik G, Gommers D. Detection of 'best' positive end-expiratory pressure derived from electrical impedance tomography parameters during a decremental positive end-expiratory pressure trial. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2014; 18:R95. [PMID: 24887391 PMCID: PMC4095609 DOI: 10.1186/cc13866] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Accepted: 05/01/2014] [Indexed: 01/21/2023]
Abstract
Introduction This study compares different parameters derived from electrical impedance tomography (EIT) data to define ‘best’ positive end-expiratory pressure (PEEP) during a decremental PEEP trial in mechanically-ventilated patients. ‘Best’ PEEP is regarded as minimal lung collapse and overdistention in order to prevent ventilator-induced lung injury. Methods A decremental PEEP trial (from 15 to 0 cm H2O PEEP in 4 steps) was performed in 12 post-cardiac surgery patients on the ICU. At each PEEP step, EIT measurements were performed and from this data the following were calculated: tidal impedance variation (TIV), regional compliance, ventilation surface area (VSA), center of ventilation (COV), regional ventilation delay (RVD index), global inhomogeneity (GI index), and intratidal gas distribution. From the latter parameter we developed the ITV index as a new homogeneity parameter. The EIT parameters were compared with dynamic compliance and the PaO2/FiO2 ratio. Results Dynamic compliance and the PaO2/FiO2 ratio had the highest value at 10 and 15 cm H2O PEEP, respectively. TIV, regional compliance and VSA had a maximum value at 5 cm H2O PEEP for the non-dependent lung region and a maximal value at 15 cm H2O PEEP for the dependent lung region. GI index showed the lowest value at 10 cm H2O PEEP, whereas for COV and the RVD index this was at 15 cm H2O PEEP. The intratidal gas distribution showed an equal contribution of both lung regions at a specific PEEP level in each patient. Conclusion In post-cardiac surgery patients, the ITV index was comparable with dynamic compliance to indicate ‘best’ PEEP. The ITV index can visualize the PEEP level at which ventilation of the non-dependent region is diminished, indicating overdistention. Additional studies should test whether application of this specific PEEP level leads to better outcome and also confirm these results in patients with acute respiratory distress syndrome.
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Ferrando C, Mugarra A, Gutierrez A, Carbonell JA, García M, Soro M, Tusman G, Belda FJ. Setting Individualized Positive End-Expiratory Pressure Level with a Positive End-Expiratory Pressure Decrement Trial After a Recruitment Maneuver Improves Oxygenation and Lung Mechanics During One-Lung Ventilation. Anesth Analg 2014; 118:657-65. [DOI: 10.1213/ane.0000000000000105] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Yang Y, Huang Y, Tang R, Chen Q, Hui X, Li Y, Yu Q, Zhao H, Qiu H. Optimization of positive end-expiratory pressure by volumetric capnography variables in lavage-induced acute lung injury. ACTA ACUST UNITED AC 2013; 87:75-83. [PMID: 24296453 DOI: 10.1159/000354787] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 07/13/2013] [Indexed: 11/19/2022]
Abstract
BACKGROUND In the acute respiratory distress syndrome (ARDS), lung-protective ventilation strategies combine the delivery of small tidal volumes (VT) with sufficient positive end-expiratory pressure (PEEP). However, an optimal approach guiding the setting of PEEP has not been defined. Monitoring volumetric capnography is useful to detect changes in lung aeration. OBJECTIVES The aim of this study was to determine whether volumetric capnography may be a useful method to determine the optimal PEEP in ARDS. METHODS In 8 lung-lavaged piglets, PEEP was reduced from 20 to 4 cm H2O in steps of 4 cm H2O every 10 min followed by full lung recruitment. Volumetric capnography, respiratory mechanics, blood gas analysis, hemodynamic data and whole-lung computed tomography scans were obtained at each PEEP level. RESULTS After lung recruitment, end-expiratory lung volume progressively decreased from 1,160 ± 273 ml at PEEP 20 cm H2O to 314 ± 86 ml at PEEP 4 cm H2O. The ratio of alveolar dead space (VDalv) to alveolar VT (VTalv) and the phase III slope of volumetric capnography (SIII) reached a minimum at PEEP 16 cm H2O. At this PEEP level, overaerated lung regions were significantly reduced, nonaerated lung regions did not increase, and partial pressure of oxygen in arterial blood/fraction of inspired oxygen (P/F) and static respiratory system compliance (Crs) reached a maximum. At PEEP levels <16 cm H2O, nonaerated lung regions significantly increased, P/F and Crs deteriorated, and VDalv/VTalv and SIII began to increase. CONCLUSIONS In this surfactant-depleted model, PEEP at the lowest VDalv/VTalv and SIII allows an optimal balance between lung overinflation and collapse. Hence, volumetric capnography is a useful bedside approach to identify the optimal PEEP.
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Affiliation(s)
- Yi Yang
- Department of Critical Care Medicine, Zhong-Da Hospital, Southeast University School of Medicine, Nanjing, PR China
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Khan M, Frankel HL. Use and titration of positive end-expiratory pressure. Curr Probl Surg 2013; 50:446-51. [PMID: 24156842 DOI: 10.1067/j.cpsurg.2013.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Corrections of Enghoff's dead space formula for shunt effects still overestimate Bohr's dead space. Respir Physiol Neurobiol 2013; 189:99-105. [PMID: 23827851 DOI: 10.1016/j.resp.2013.06.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 05/19/2013] [Accepted: 06/24/2013] [Indexed: 12/28/2022]
Abstract
Dead space ratio is determined using Enghoff's modification (VD(B-E)/VT) of Bohr's formula (VD(Bohr)/VT) in which arterial is used as a surrogate of alveolar PCO₂. In presence of intrapulmonary shunt Enghoff's approach overestimates dead space. In 40 lung-lavaged pigs we evaluated the Kuwabara's and Niklason's algorithms to correct for shunt effects and hypothesized that corrected VD(B-E)/VT should provide similar values as VD(Bohr)/VT. We analyzed 396 volumetric capnograms and arterial and mixed-venous blood samples to calculate VD(Bohr)/VT and VD(B-E)/VT. Thereafter, we corrected the latter for shunt effects using Kuwabara's (K) VD(B-E)/VT and Niklason's (N) VD(B-E)/VT algorithms. Uncorrected VD(B-E)/VT (mean ± SD of 0.70 ± 0.10) overestimated VD(Bohr)/VT (0.59 ± 0.12) (p < 0.05), over the entire range of shunts. Mean (K) VD(B-E)/VT was significantly higher than VD(Bohr)/VT (0.67 ± 0.08, bias -0.085, limits of agreement -0.232 to 0.085; p < 0.05) whereas (N)VD(B-E)/VT showed a better correction for shunt effects (0.64 ± 0.09, bias 0.048, limits of agreement -0.168 to 0.072; p < 0.05). Neither Kuwabara's nor Niklason's algorithms were able to correct Enghoff's dead space formula for shunt effects.
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Gaidukov KM, Raibuzhis EN, Hussain A, Teterin AY, Smetkin AA, Kuzkov VV, Malbrain MLNG, Kirov MY. Effect of intra-abdominal pressure on respiratory function in patients undergoing ventral hernia repair. World J Crit Care Med 2013; 2:9-16. [PMID: 24701411 PMCID: PMC3953861 DOI: 10.5492/wjccm.v2.i2.9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 03/20/2013] [Accepted: 04/27/2013] [Indexed: 02/06/2023] Open
Abstract
AIM To determine the influence of intra-abdominal pressure (IAP) on respiratory function after surgical repair of ventral hernia and to compare two different methods of IAP measurement during the perioperative period. METHODS Thirty adult patients after elective repair of ventral hernia were enrolled into this prospective study. IAP monitoring was performed via both a balloon-tipped nasogastric probe [intragastric pressure (IGP), CiMON, Pulsion Medical Systems, Munich, Germany] and a urinary catheter [intrabladder pressure (IBP), UnoMeterAbdo-Pressure Kit, UnoMedical, Denmark] on five consecutive stages: (1) after tracheal intubation (AI); (2) after ventral hernia repair; (3) at the end of surgery; (4) during spontaneous breathing trial through the endotracheal tube; and (5) at 1 h after tracheal extubation. The patients were in the complete supine position during all study stages. RESULTS The IAP (measured via both techniques) increased on average by 12% during surgery compared to AI (P < 0.02) and by 43% during spontaneous breathing through the endotracheal tube (P < 0.01). In parallel, the gradient between РаСО2 and EtCO2 [Р(а-et)CO2] rose significantly, reaching a maximum during the spontaneous breathing trial. The PаO2/FiO2 decreased by 30% one hour after tracheal extubation (P = 0.02). The dynamic compliance of respiratory system reduced intraoperatively by 15%-20% (P < 0.025). At all stages, we observed a significant correlation between IGP and IBP (r = 0.65-0.81, P < 0.01) with a mean bias varying from -0.19 mmHg (2SD 7.25 mmHg) to -1.06 mm Hg (2SD 8.04 mmHg) depending on the study stage. Taking all paired measurements together (n = 133), the median IGP was 8.0 (5.5-11.0) mmHg and the median IBP was 8.8 (5.8-13.1) mmHg. The overall r (2) value (n = 30) was 0.76 (P < 0.0001). Bland and Altman analysis showed an overall bias for the mean values per patient of 0.6 mmHg (2SD 4.2 mmHg) with percentage error of 45.6%. Looking at changes in IAP between the different study stages, we found an excellent concordance coefficient of 94.9% comparing ΔIBP and ΔIGP (n = 117). CONCLUSION During ventral hernia repair, the IAP rise is accompanied by changes in Р(а-et)CO2 and PаO2/FiO2-ratio. Estimation of IAP via IGP or IBP demonstrated excellent concordance.
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Moens Y. Mechanical Ventilation and Respiratory Mechanics During Equine Anesthesia. Vet Clin North Am Equine Pract 2013; 29:51-67. [DOI: 10.1016/j.cveq.2012.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Kim SH, Choi YS, Lee JG, Park IH, Oh YJ. Effects of a 1:1 inspiratory to expiratory ratio on respiratory mechanics and oxygenation during one-lung ventilation in the lateral decubitus position. Anaesth Intensive Care 2012. [PMID: 23194211 DOI: 10.1177/0310057x1204000613] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Prolonged inspiratory to expiratory (I:E) ratio ventilation may have both positive and negative effects on respiratory mechanics and oxygenation during one-lung ventilation (OLV), but definitive information is currently lacking. We therefore compared the effects of volume-controlled ventilation with I:E ratios of 1:1 and 1:2 on respiratory mechanics and oxygenation during OLV. Fifty-six patients undergoing thoracoscopic lobectomy were randomly assigned volume-controlled ventilation with an I:E ratio of 1:1 (group 1:1, n=28) or 1:2 (group 1:2, n=28) during OLV. Arterial and central venous blood gas analyses and respiratory variables were recorded 15 minutes into two-lung ventilation, at 30 and 60 minutes during OLV, and 15 minutes after two-lung ventilation was re-initiated. Peak and plateau airway pressures in cmH2O [standard deviation] during OLV were significantly lower in group 1:1 than in group 1:2 (P <0.01) (19 [3] and 23 [4]; 16 [3] and 19 [5], respectively). The arterial to end-tidal carbon dioxide tension difference was significantly lower in group 1:1 than in group 1:2 (P <0.01), (0.5 [0.3] and 1.1 [0.5]). There were no significant differences in PaO2 during OLV between the two groups (OLV30, P=0.856; OLV60, P=0.473). In summary, volume-controlled ventilation with an I:E ratio of 1:1 reduced peak and plateau airway pressures improved dynamic compliance and efficiency of alveolar ventilation, but it did not improve arterial oxygenation in a substantial manner. Furthermore, the associated increase in mean airway pressure might have reduced cardiac output, resulting in a lower central venous oxygen saturation.
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Affiliation(s)
- S H Kim
- Department of Anaesthesiology and Pain Medicine, Anaesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea
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Brochard L, Martin GS, Blanch L, Pelosi P, Belda FJ, Jubran A, Gattinoni L, Mancebo J, Ranieri VM, Richard JCM, Gommers D, Vieillard-Baron A, Pesenti A, Jaber S, Stenqvist O, Vincent JL. Clinical review: Respiratory monitoring in the ICU - a consensus of 16. Crit Care 2012; 16:219. [PMID: 22546221 PMCID: PMC3681336 DOI: 10.1186/cc11146] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Monitoring plays an important role in the current management of patients with acute respiratory failure but sometimes lacks definition regarding which 'signals' and 'derived variables' should be prioritized as well as specifics related to timing (continuous versus intermittent) and modality (static versus dynamic). Many new techniques of respiratory monitoring have been made available for clinical use recently, but their place is not always well defined. Appropriate use of available monitoring techniques and correct interpretation of the data provided can help improve our understanding of the disease processes involved and the effects of clinical interventions. In this consensus paper, we provide an overview of the important parameters that can and should be monitored in the critically ill patient with respiratory failure and discuss how the data provided can impact on clinical management.
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Affiliation(s)
- Laurent Brochard
- Department of Intensive Care, Hôpitaux Universitaires de Genève, Rue
Gabrielle-Perret-Gentil 4, 1211 Geneva, Switzerland; and Université de
Genève, Switzerland
| | - Greg S Martin
- Division of Pulmonary, Allergy and Critical Care, Emory University School of
Medicine, Grady Memorial Hospital, 615 Michael Street, Suite 205, Atlanta, GA
30322, USA
| | - Lluis Blanch
- Critical Care Center, Corporacio Sanitaria Universitària Parc Tauli,
Universitat Autònoma de Barcelona, 08208 Sabadell, Spain, CIBER Enfermedades
Respiratorias, ISCiii, Madrid, Spain
| | - Paolo Pelosi
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa,
San Martino Hospital, Largo Rosanna Benzi 8 16132, Genoa, Italy
| | - F Javier Belda
- Department of Anesthesia and Surgical Critical Care, Hospital Clínico
Universitario, Avda Blasco Ibañez 17, 46010 Valencia, Spain
| | - Amal Jubran
- Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. VA Hospital,
111N, 5th Avenue and Roosevelt Road, Hines, IL 60141, USA
| | - Luciano Gattinoni
- Dipartimento di Anestesiologia, Terapia Intensive e Scienze Dermatologiche, and
Dipartimento do Anestesia, Rianimazione (Intensive e Subintensiva) e Terapia del
Dolore, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico,
Università degli Studi di Milano, via F, Sforza 35, 20122, Milan, Italy
| | - Jordi Mancebo
- Servicio Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Carrer St.
Quintí 89, 08041 Barcelona, Spain
| | - V Marco Ranieri
- Department of Anesthesia and Intensive Care Medicine, University of Turin, S.
Giovanni Battista, Molinette Hospital, Corso Dogliotti 14, 10126 Turin, Italy
| | - Jean-Christophe M Richard
- Department of Intensive Care, Hôpitaux Universitaires de Genève, Rue
Gabrielle-Perret-Gentil 4, 1211 Geneva, Switzerland; and Université de
Genève, Switzerland
| | - Diederik Gommers
- Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, 3015CE
Rotterdam, The Netherlands
| | - Antoine Vieillard-Baron
- Intensive Care Unit, Section Thorax - Vascular disease - Abdomen - Metabolism, CHU
Ambroise Paré, 9 avenue Charles-de-Gaulle, 92104 Boulogne, France
| | - Antonio Pesenti
- Anesthesia and Intensive Care, University of Milan-Bicocca, A.O. Ospedale S.
Gerardo, Via Pergolesi 33, 20900 Monza, Italy
| | - Samir Jaber
- Department of Critical Care Medicine and Anesthesiology, Saint Eloi University
Hospital and Montpellier School of Medicine, 80 Avenue Augustin Fliche, 34295
Montpellier - Cedex 5, France
| | - Ola Stenqvist
- Department of Anesthesiology and Intensive Care, Sahlgrenska University Hospital,
Bla Straket 5, Gothenburg, SE 413 45, Sweden
| | - Jean-Louis Vincent
- Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles,
808 route de Lennik, 1070 Brussels, Belgium
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Volumetric capnography curves as lung function test to confirm bronchoconstriction after carbachol challenge in sedated dogs. Res Vet Sci 2012; 93:1418-25. [DOI: 10.1016/j.rvsc.2012.04.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 11/25/2011] [Accepted: 04/12/2012] [Indexed: 11/30/2022]
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Non-invasive accurate measurement of arterial PCO2 in a pediatric animal model. J Clin Monit Comput 2012; 27:147-55. [DOI: 10.1007/s10877-012-9403-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
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Effects of a stepwise lung recruitment manoeuvre and positive end-expiratory pressure on lung compliance and arterial blood oxygenation in healthy dogs. Vet J 2012; 194:89-93. [DOI: 10.1016/j.tvjl.2012.02.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 02/11/2012] [Accepted: 02/26/2012] [Indexed: 11/22/2022]
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Mosing M, Iff I, Hirt R, Moens Y, Tusman G. Evaluation of variables to describe the shape of volumetric capnography curves during bronchoconstriction in dogs. Res Vet Sci 2012; 93:386-92. [DOI: 10.1016/j.rvsc.2011.05.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 03/29/2011] [Accepted: 05/17/2011] [Indexed: 10/18/2022]
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Tusman G, Sipmann FS, Bohm SH. Rationale of Dead Space Measurement by Volumetric Capnography. Anesth Analg 2012; 114:866-74. [DOI: 10.1213/ane.0b013e318247f6cc] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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49
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Unzueta C, Tusman G, Suarez-Sipmann F, Böhm S, Moral V. Alveolar recruitment improves ventilation during thoracic surgery: a randomized controlled trial. Br J Anaesth 2012; 108:517-24. [DOI: 10.1093/bja/aer415] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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50
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Lung aeration during ventilation after recruitment guided by tidal elimination of carbon dioxide and dynamic compliance was better than after end-tidal carbon dioxide targeted ventilation: a computed tomography study in surfactant-depleted piglets. Pediatr Crit Care Med 2011; 12:e362-8. [PMID: 21263364 DOI: 10.1097/pcc.0b013e31820aba6e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To test the hypothesis that tidal elimination of carbon dioxide and dynamic compliance guided lung recruitment and positive end-expiratory pressure titration in surfactant-depleted piglets result in improved aeration (repeated computed tomography scans) and reduced ventilation pressures compared to those of a control group with conventional end-tidal carbon dioxide targeted ventilation. DESIGN Prospective animal investigation. SETTING Clinical physiology research laboratory. SUBJECTS Seventeen saline-lavaged piglets. INTERVENTIONS The piglets were initially ventilated at an end-inspiratory pressure of 20 cm H2O, a positive end-expiratory pressure of 5 cm H2O, and a tidal volume of 10 mL kg for an end-tidal carbon dioxide target of 30-45 torr followed by 5 mins of ventilation without positive end-expiratory pressure. After this, the control group was ventilated for the same end-tidal carbon dioxide target during the study period. In the recruitment group, the protocol started with an increase of the positive end-expiratory pressure to 15 cm H2O. The end-inspiratory pressure was then increased in steps of 3 cm H2O to a tidal elimination of carbon dioxide peak/plateau in one recruitment group and further increased in two steps in a second recruitment group. A downward positive end-expiratory pressure titration was followed by continuous dynamic compliance monitoring. The "open lung positive end-expiratory pressure" was set 2 cm H2O above the positive end-expiratory pressure at the first dynamic compliance decline and used for a final "open lung ventilation" period. MEASUREMENTS AND MAIN RESULTS The recruitment groups showed better aeration, lower ventilatory pressure amplitude, and better dynamic compliance than the control group at the end of the study. Recruitment using airway pressures above the tidal elimination of carbon dioxide peak/plateau did not improve aeration. Using end-tidal carbon dioxide targeted ventilation in the control group restored aeration after the ventilation without positive end-expiratory pressure, but no recruitment or improvement of dynamic compliance was measured. CONCLUSIONS Aeration was significantly better after recruitment and positive end-expiratory pressure titration than in a control group managed by "conventional" end-tidal carbon dioxide targeted ventilation. An increase of the end-inspiratory pressure above the tidal elimination of carbon dioxide peak/plateau did not result in an increased amount of normally aerated lung. A recruitment maneuver resulted in a lower ventilatory amplitude for achieving a target tidal volume and better dynamic compliance at the end of the study period compared to those of the control group.
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