scholarly journals Positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome: the heterogeneous effects

Critical Care ◽  
2021 ◽  
Vol 25 (1) ◽  
Author(s):  
Davide Chiumello ◽  
Matteo Bonifazi ◽  
Tommaso Pozzi ◽  
Paolo Formenti ◽  
Giuseppe Francesco Sferrazza Papa ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Dead Space ◽  
Respiratory Mechanics ◽  
Peep Level ◽  
Lung Mechanics ◽  
Mechanical Power ◽  
Respiratory System Compliance ◽  
Lung Elastance ◽  
Lung Stress

Abstract Background We hypothesized that as CARDS may present different pathophysiological features than classic ARDS, the application of high levels of end-expiratory pressure is questionable. Our first aim was to investigate the effects of 5–15 cmH2O of PEEP on partitioned respiratory mechanics, gas exchange and dead space; secondly, we investigated whether respiratory system compliance and severity of hypoxemia could affect the response to PEEP on partitioned respiratory mechanics, gas exchange and dead space, dividing the population according to the median value of respiratory system compliance and oxygenation. Thirdly, we explored the effects of an additional PEEP selected according to the Empirical PEEP-FiO2 table of the EPVent-2 study on partitioned respiratory mechanics and gas exchange in a subgroup of patients. Methods Sixty-one paralyzed mechanically ventilated patients with a confirmed diagnosis of SARS-CoV-2 were enrolled (age 60 [54–67] years, PaO2/FiO2 113 [79–158] mmHg and PEEP 10 [10–10] cmH2O). Keeping constant tidal volume, respiratory rate and oxygen fraction, two PEEP levels (5 and 15 cmH2O) were selected. In a subgroup of patients an additional PEEP level was applied according to an Empirical PEEP-FiO2 table (empirical PEEP). At each PEEP level gas exchange, partitioned lung mechanics and hemodynamic were collected. Results At 15 cmH2O of PEEP the lung elastance, lung stress and mechanical power were higher compared to 5 cmH2O. The PaO2/FiO2, arterial carbon dioxide and ventilatory ratio increased at 15 cmH2O of PEEP. The arterial–venous oxygen difference and central venous saturation were higher at 15 cmH2O of PEEP. Both the mechanics and gas exchange variables significantly increased although with high heterogeneity. By increasing the PEEP from 5 to 15 cmH2O, the changes in partitioned respiratory mechanics and mechanical power were not related to hypoxemia or respiratory compliance. The empirical PEEP was 18 ± 1 cmH2O. The empirical PEEP significantly increased the PaO2/FiO2 but also driving pressure, lung elastance, lung stress and mechanical power compared to 15 cmH2O of PEEP. Conclusions In COVID-19 ARDS during the early phase the effects of raising PEEP are highly variable and cannot easily be predicted by respiratory system characteristics, because of the heterogeneity of the disease.

scholarly journals Lung Mechanics in Type L CoVID-19 Pneumonia: A Pseudo-Normal ARDS.

2020 ◽  
Author(s):  
Lorenzo Viola ◽  
Emanuele Russo ◽  
Marco Benni ◽  
Emiliano Gamberini ◽  
Alessandro Circelli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Blood Gases ◽  
Lung Mechanics ◽  
Prone Positioning ◽  
Arterial Blood Gases ◽  
Arterial Blood ◽  
Esophageal Balloon ◽  
Early Phases

Abstract Background. This study was conceived to provide systematic data about lung mechanics during early phases of CoVID-19 pneumonia, as long as to explore its variations during prone positioning. Methods. We enrolled four patients hospitalized in the Intensive Care Unit of “M. Bufalini” hospital, Cesena (Italy); after the positioning of an esophageal balloon, we measured mechanical power, respiratory system and transpulmonary parameters and arterial blood gases every 6 hours, just before decubitus change and 1 hour after prono-supination. Results. Both respiratory system and transpulmonary compliance and driving pressure confirmed the pseudo-normal respiratory mechanics of early CoVID-19 pneumonia (respectively, CRS 40.8 ml/cmH2O and DPRS 9.7 cmH2O; CL 53.1 ml/cmH2O and DPL 7.9 cmH2O). Interestingly, prone positioning involved a worsening in respiratory mechanical properties (CRS,SUP 56.3 ml/cmH2O and CRS,PR 41.5 ml/cmH2O – P 0.37; CL,SUP 80.8 ml/cmH2O and CL,PR 53.2 ml/cmH2O – P 0.23). Conclusions. Despite the severe ARDS pattern, respiratory system and lung mechanical properties during CoVID-19 pneumonia are pseudo-normal and tend to worsen during pronation. Trial registration. Restrospectively registered.

scholarly journals Radiological pattern in ARDS patients: partitioned respiratory mechanics, gas exchange and lung recruitability

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Silvia Coppola ◽  
Tommaso Pozzi ◽  
Martina Gurgitano ◽  
Alessandro Liguori ◽  
Ejona Duka ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Recruitment Maneuver ◽  
Blood Gas Analysis ◽  
Gas Analysis ◽  
Driving Pressure ◽  
Lung Weight ◽  
Focal Pattern ◽  
Lung Ct

Abstract Background The ARDS is characterized by different degrees of impairment in oxygenation and distribution of the lung disease. Two radiological patterns have been described: a focal and a diffuse one. These two patterns could present significant differences both in gas exchange and in the response to a recruitment maneuver. At the present time, it is not known if the focal and the diffuse pattern could be characterized by a difference in the lung and chest wall mechanical characteristics. Our aims were to investigate, at two levels of PEEP, if focal vs. diffuse ARDS patterns could be characterized by different lung CT characteristics, partitioned respiratory mechanics and lung recruitability. Methods CT patterns were analyzed by two radiologists and were classified as focal or diffuse. The changes from 5 to 15 cmH2O in blood gas analysis and partitioned respiratory mechanics were analyzed. Lung CT scan was performed at 5 and 45 cmH2O of PEEP to evaluate lung recruitability. Results One-hundred and ten patients showed a diffuse pattern, while 58 showed a focal pattern. At 5 cmH2O of PEEP, the driving pressure and the elastance, both the respiratory system and of the lung, were significantly higher in the diffuse pattern compared to the focal (14 [11–16] vs 11 [9–15 cmH2O; 28 [23–34] vs 21 [17–27] cmH2O/L; 22 [17–28] vs 14 [12–19] cmH2O/L). By increasing PEEP, the driving pressure and the respiratory system elastance significantly decreased in diffuse pattern, while they increased or did not change in the focal pattern (Δ15-5: − 1 [− 2 to 1] vs 0 [− 1 to 2]; − 1 [− 4 to 2] vs 1 [− 2 to 5]). At 5 cmH2O of PEEP, the diffuse pattern had a lower lung gas (743 [537–984] vs 1222 [918–1974] mL) and higher lung weight (1618 [1388–2001] vs 1222 [1059–1394] g) compared to focal pattern. The lung recruitability was significantly higher in diffuse compared to focal pattern 21% [13–29] vs 11% [6–16]. Considering the median of lung recruitability of the whole population (16.1%), the recruiters were 65% and 22% in the diffuse and focal pattern, respectively. Conclusions An early identification of lung morphology can be useful to choose the ventilatory setting. A diffuse pattern has a better response to the increase of PEEP and to the recruitment maneuver.

scholarly journals Differential Effects of Endotracheal Suctioning on Gas Exchanges in Patients with Acute Respiratory Failure under Pressure-Controlled and Volume-Controlled Ventilation

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Xiao-Wei Liu ◽  
Yan Jin ◽  
Tao Ma ◽  
Bo Qu ◽  
Zhi Liu
Keyword(s):  
Gas Exchange ◽  
Respiratory Mechanics ◽  
Initial Level ◽  
Lung Compliance ◽  
Respiratory System Compliance ◽  
Endotracheal Suctioning ◽  
Gas Exchanges ◽  
Volume Controlled Ventilation ◽  
Volume Controlled ◽  
Pressure Controlled

This study was conducted to evaluate the effects of open endotracheal suctioning on gas exchange and respiratory mechanics in ARF patients under the modes of PCV or VCV. Ninety-six ARF patients were treated with open endotracheal suctioning and their variations in respiratory mechanics and gas exchange after the suctions were compared. Under PCV mode, compared with the initial level of tidal volume (VT), ARF patients showed 30.0% and 27.8% decrease at 1 min and 10 min, respectively. Furthermore, the initial respiratory system compliance (Crs) decreased by 29.6% and 28.5% at 1 min and 10 min, respectively. Under VCV mode, compared with the initial level, 38.6% and 37.5% increase in peak airway pressure (PAP) were found at 1 min and 10 min, respectively. Under PCV mode, the initial PaO2increased by 6.4% and 10.2 % at 3 min and 10 min, respectively, while 18.9% and 30.6% increase of the initial PaO2were observed under VCV mode. Summarily, endotracheal suctioning may impair gas exchange and decrease lung compliance in ARF patients receiving mechanical ventilation under both PCV and VCV modes, but endotracheal suctioning effects on gas exchange were more severe and longer-lasting under PCV mode than VCV.

scholarly journals Comparative effects of flow vs. volume-controlled one-lung ventilation on gas exchange and respiratory system mechanics in pigs

2020 ◽  
Vol 8 (S1) ◽  
Author(s):  
Jakob Wittenstein ◽  
Martin Scharffenberg ◽  
Xi Ran ◽  
Diana Keller ◽  
Pia Michler ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Lung Ventilation ◽  
Minute Volume ◽  
Mechanical Power ◽  
One Lung Ventilation ◽  
Impedance Tomography ◽  
Controlled Ventilation ◽  
Ventilation Modes ◽  
Volume Controlled

Abstract Background Flow-controlled ventilation (FCV) allows expiratory flow control, reducing the collapse of the airways during expiration. The performance of FCV during one-lung ventilation (OLV) under intravascular normo- and hypovolaemia is currently unknown. In this explorative study, we hypothesised that OLV with FCV improves PaO2 and reduces mechanical power compared to volume-controlled ventilation (VCV). Sixteen juvenile pigs were randomly assigned to one of two groups: (1) intravascular normovolaemia (n = 8) and (2) intravascular hypovolaemia (n = 8). To mimic inflammation due to major thoracic surgery, a thoracotomy was performed, and 0.5 μg/kg/h lipopolysaccharides from Escherichia coli continuously administered intravenously. Animals were randomly assigned to OLV with one of two sequences (60 min per mode): (1) VCV–FCV or (2) FCV–VCV. Variables of gas exchange, haemodynamics and respiratory signals were collected 20, 40 and 60 min after initiation of OLV with each mechanical ventilation mode. The distribution of ventilation was determined using electrical impedance tomography (EIT). Results Oxygenation did not differ significantly between modes (P = 0.881). In the normovolaemia group, the corrected expired minute volume (P = 0.022) and positive end-expiratory pressure (PEEP) were lower during FCV than VCV. The minute volume (P ≤ 0.001), respiratory rate (P ≤ 0.001), total PEEP (P ≤ 0.001), resistance of the respiratory system (P ≤ 0.001), mechanical power (P ≤ 0.001) and resistive mechanical power (P ≤ 0.001) were lower during FCV than VCV irrespective of the volaemia status. The distribution of ventilation did not differ between both ventilation modes (P = 0.103). Conclusions In a model of OLV in normo- and hypovolemic pigs, mechanical power was lower during FCV compared to VCV, without significant differences in oxygenation. Furthermore, the efficacy of ventilation was higher during FCV compared to VCV during normovolaemia.

scholarly journals Lung mechanics in type L CoVID-19 pneumonia: a pseudo-normal ARDS

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Lorenzo Viola ◽  
Emanuele Russo ◽  
Marco Benni ◽  
Emiliano Gamberini ◽  
Alessandro Circelli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Blood Gases ◽  
Lung Mechanics ◽  
Prone Positioning ◽  
Arterial Blood Gases ◽  
Arterial Blood ◽  
Esophageal Balloon ◽  
Early Phases

Abstract Background This study was conceived to provide systematic data about lung mechanics during early phases of CoVID-19 pneumonia, as long as to explore its variations during prone positioning. Methods We enrolled four patients hospitalized in the Intensive Care Unit of “M. Bufalini” hospital, Cesena (Italy); after the positioning of an esophageal balloon, we measured mechanical power, respiratory system and transpulmonary parameters and arterial blood gases every 6 hours, just before decubitus change and 1 hour after prono-supination. Results Both respiratory system and transpulmonary compliance and driving pressure confirmed the pseudo-normal respiratory mechanics of early CoVID-19 pneumonia (respectively, CRS 40.8 ml/cmH2O and DPRS 9.7 cmH2O; CL 53.1 ml/cmH2O and DPL 7.9 cmH2O). Interestingly, prone positioning involved a worsening in respiratory mechanical properties throughout time (CRS,SUP 56.3 ml/cmH2O and CRS,PR 41.5 ml/cmH2O – P 0.37; CL,SUP 80.8 ml/cmH2O and CL,PR 53.2 ml/cmH2O – P 0.23). Conclusions Despite the severe ARDS pattern, respiratory system and lung mechanical properties during CoVID-19 pneumonia are pseudo-normal and tend to worsen during pronation. Trial registration Restrospectively registered.

scholarly journals Respiratory system compliance at the same PEEP level is similar in COVID and non-COVID ARDS

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Federica Fusina ◽  
Filippo Albani ◽  
Serena Crisci ◽  
Alessandro Morandi ◽  
Francesca Tansini ◽  
...  
Keyword(s):  
Propensity Score ◽  
Linear Model ◽  
Respiratory System ◽  
Peep Level ◽  
Respiratory System Compliance ◽  
Positive End Expiratory Pressure ◽  
Anthropometric Characteristics ◽  
Residual Capacity ◽  
Secondary Analyses ◽  
Clinically Significant

Abstract Background The comparison of respiratory system compliance (Crs) between COVID and non-COVID ARDS patients has been the object of debate, but few studies have evaluated it when considering applied positive end expiratory pressure (PEEP), which is one of the known determinants of Crs itself. The aim of this study was to compare Crs taking into account the applied PEEP. Methods Two cohorts of patients were created: those with COVID-ARDS and those with non-COVID ARDS. In the whole sample the association between Crs and type of ARDS at different PEEP levels was adjusted for anthropometric and clinical variables. As secondary analyses, patients were matched for predicted functional residual capacity and the same association was assessed. Moreover, the association between Crs and type of ARDS was reassessed at predefined PEEP level of 0, 5, 10, and 15 cmH2O with a propensity score-weighted linear model. Results 367 patients were included in the study, 276 patients with COVID-ARDS and 91 with non-COVID ARDS. The association between Crs and type of ARDS was not significant in both the complete cohorts (p = 0.17) and in the matched cohorts (p = 0.92). This was true also for the propensity score weighted association at PEEP 5, 10 and 15 cmH2O, while it was statistically significant at PEEP 0 (with a median difference of 3 ml/cmH2O, which in our opinion is not clinically significant). Conclusions The compliance of the respiratory system is similar between COVID ARDS and non-COVID ARDS when calculated at the same PEEP level and while taking into account patients’ anthropometric characteristics.

Passive total respiratory system compliance and gas exchange in newborns with hyaline membrane disease

1989 ◽  
Vol 6 (1) ◽  
pp. 2-7 ◽  
Author(s):  
E. Dreizzen ◽  
M. Migdal ◽  
J.P. Praud ◽  
M.A. Saby ◽  
B. Chambille ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Hyaline Membrane Disease ◽  
Respiratory System Compliance ◽  
Hyaline Membrane

scholarly journals The interactions between respiratory and cardiovascular systems in systolic heart failure

2020 ◽  
Vol 128 (1) ◽  
pp. 214-224 ◽  
Author(s):  
Troy James Cross ◽  
Chul-Ho Kim ◽  
Bruce D. Johnson ◽  
Sophie Lalande
Keyword(s):  
Heart Failure ◽  
Gas Exchange ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Systolic Heart Failure ◽  
Multiple Organ ◽  
Pulmonary Gas Exchange ◽  
Organ Systems ◽  
Respiratory Systems ◽  
The Impact

Heart failure (HF) is a complex and multifaceted disease. The disease affects multiple organ systems, including the respiratory system. This review provides three unique examples illustrating how the cardiovascular and respiratory systems interrelate because of the pathology of HF. Specifically, these examples outline the impact of HF pathophysiology on 1) respiratory mechanics and the mechanical “cost” of breathing; 2) mechanical interactions of the heart and lungs; and on 3) abnormalities of pulmonary gas exchange during exercise, and how this may be applied to treatment. The goal of this review is to, therefore, raise the awareness that HF, though primarily a disease of the heart, is accompanied by marked pathology of the respiratory system.

scholarly journals Electrical Impedance Tomography Analysis Between Two Similar Respiratory System Compliance During Decremetal PEEP Titration in ARDS Patients

2021 ◽  
Author(s):  
Po-Lan Su ◽  
Wei-Chieh Lin ◽  
Yen-Fen Ko ◽  
Kuo-Sung Cheng ◽  
Chang-Wen Chen
Keyword(s):  
Electrical Impedance Tomography ◽  
Respiratory System ◽  
Electrical Impedance ◽  
Peep Level ◽  
Stress Index ◽  
Respiratory System Compliance ◽  
Impedance Tomography ◽  
Additional Information ◽  
Alveolar Collapse ◽  
The Difference

Abstract Purpose The positive end-expiratory pressure (PEEP) level with best respiratory system compliance (Crs) is frequently used for PEEP selection in acute respiratory distress syndrome (ARDS) patients. On occasion, two similar best Crs (where the difference between the Crs of two PEEP levels is < 1 ml/cm H2O) may be identified during decremental PEEP titration. Selecting PEEP under such conditions is challenging. The aim of this study was to provide supplementary rationale for PEEP selection by assessing the global and regional ventilation distributions between two PEEP levels in this situation. Methods Eight ARDS cases with similar best Crs at two different PEEP levels were analyzed using examination-specific electrical impedance tomography (EIT) measures and airway stress index (SIaw). Five Crs were measured at PEEP values of 25 cm H2O (PEEP25), 20 cm H2O (PEEP20), 15 cm H2O (PEEPH), 11 cm H2O (PEEPI), and 7 cm H2O (PEEPL). The higher PEEP value of the two PEEPs with similar best Crs was designated as PEEPupper, while the lower designated as PEEPlower. Results PEEPH and PEEPI shared the best Crs in two cases, while similar Crs was found at PEEPI and PEEPL in the remaining six cases. SIaw was higher with PEEPupper as compared to PEEPlower (1.06 ± 0.10 versus 0.99 ± 0.09, p = 0.05). Proportion of lung hyperdistension was significantly higher with PEEPupper than PEEPlower (7.0 ± 5.1% versus 0.3 ± 0.5%, p = 0.0002). In contrast, proportion of recruitable lung collapse was higher with PEEPlower than PEEPupper (18.6 ± 4.4% versus 5.9 ± 3.7%, p < 0.0001). Cyclic alveolar collapse and reopening during tidal breathing was higher at PEEPlower than PEEPupper (34.4 ± 19.3% versus 16.0 ± 9.1%, p = 0.046). The intratidal gas distribution (ITV) index was also significantly higher at PEEPlower than PEEPupper (2.6 ± 1.3 versus 1.8 ± 0.7, p = 0.042). Conclusions PEEPupper is a rational selection in ARDS cases with two similar best Crs. EIT provides additional information for the selection of PEEP in such circumstances.

Partial liquid breathing with perflubron improves arterial oxygenation in acute canine lung injury

1993 ◽  
Vol 75 (6) ◽  
pp. 2696-2702 ◽  
Author(s):  
S. E. Curtis ◽  
J. T. Peek ◽  
D. R. Kelly
Keyword(s):  
Gas Exchange ◽  
Lung Mechanics ◽  
Arterial Oxygenation ◽  
Respiratory System Compliance ◽  
Perfluorocarbon Liquid ◽  
The Third ◽  
Lung Histology ◽  
Residual Capacity ◽  
O2 Delivery ◽  
Arterial Po2

Tidal liquid breathing with perfluorocarbon liquid improves lung mechanics and gas exchange in surfactant-deficient lambs. We asked whether an intratracheal dose of perflubron equal to liquid functional residual capacity (FRC) or less (partial liquid breathing) would alter gas exchange in gas-ventilated, anesthetized, and oleic acid (OA)-injured dogs. We gave eight dogs perflubron in six aliquots, each equal to one-sixth of liquid FRC [sequential dose (SEQ) group], starting 90 min after OA. Two other groups of eight dogs each received a liquid FRC dose of perflubron (60–70 ml/kg) either just before (P-Pre) or 90 min after (P-Post) OA, and eight control (CON) dogs received OA but no perflubron. In CON, SEQ, and P-Post dogs, OA caused a significant decrease in static respiratory system compliance (Crs) (1.50 +/- 0.05 to 1.15 +/- 0.06 ml.cmH2O–1.kg-1) and arterial PO2 (508 +/- 10 to 113 +/- 16 Torr) by minute 90. In P-Pre, P-Post, and after the third dose of perflubron (50% FRC) in SEQ dogs, arterial PO2 was significantly higher than that in the CON dogs but was similar to that in the CON dogs after perflubron removal. Perflubron doses less than two-thirds of liquid FRC were associated with increased Crs compared with CON dogs, but further lung filling caused a decrease in Crs. Lung histology showed widespread edema and hemorrhage and was similar in perflubron and CON dogs. O2 delivery and uptake were well maintained in all four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

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