Impact of Positive End-Expiratory Pressure and FiO 2 on Lung Mechanics and Intrapulmonary Shunt in Mechanically Ventilated Patients with ARDS Due to COVID-19 Pneumonia

Abstract

Purpose: This study aimed to investigate the effects of inspired oxygen fraction (FiO₂) and positive end-expiratory pressure (PEEP) on gas exchange in mechanically ventilated patients with COVID-19. Methods: Two FiO₂ (100%, 40%) were tested at 3 decreasing levels of PEEP (15, 10, and 5 cmH₂O). At each FiO₂ and PEEP, gas exchange, respiratory mechanics, hemodynamics, and the distribution of ventilation and perfusion were assessed with electrical impedance tomography. The impact of FiO₂ on the intrapulmonary shunt (delta shunt) was analyzed as the difference between the calculated shunt at FiO₂ 100% (shunt) and venous admixture at FiO₂ 40% (venous admixture). Results: Fourteen patients were studied. Decreasing PEEP from 15 to 10 cmH₂O did not change shunt (24 [21-28] vs 27 [24-29]%) or venous admixture (18 [15-26] vs 23 [18-34]%) while partial pressure of arterial oxygen (FiO₂ 100%) was higher at PEEP 15 (262 [198-338] vs 256 [147-315] mmHg; P < .05). Instead when PEEP was decreased from 10 to 5 cmH₂O, shunt increased to 36 [30-39]% (P < .05) and venous admixture increased to 33 [30-43]% (P < .05) and partial pressure of arterial oxygen (100%) decreased to 109 [76-177] mmHg (P < .05). At PEEP 15, administration of 100% FiO₂ resulted in a shunt greater than venous admixture at 40% FiO_2, ((24 [21-28] vs 18 [15-26]%, P = .005), delta shunt 5.5% (2.3-8.8)). Compared to PEEP 10, PEEP of 5 and 15 cmH₂O resulted in decreased global and pixel-level compliance. Cardiac output at FiO₂ 100% resulted higher at PEEP 5 (5.4 [4.4-6.5]) compared to PEEP 10 (4.8 [4.1-5.5], P < .05) and PEEP 15 cmH₂O (4.7 [4.5-5.4], P < .05). Conclusion: In this study, PEEP of 15 cmH₂O, despite resulting in the highest oxygenation, was associated with overdistension. PEEP of 5 cmH₂O was associated with increased shunt and alveolar collapse. Administration of 100% FiO₂ was associated with an increase in intrapulmonary shunt in the setting of high PEEP. Trial registration: NCT05132933.

Keywords

COVID-19 hypoxemia intrapulmonary shunt ARDS oxygen positive end-expiratory pressure compliance venous admixture

Get full access to this article

View all access options for this article.

References

ARDS Definition Task Force, Ranieri

Rubenfeld

, et al. Acute respiratory distress syndrome: the Berlin definition. JAMA. 2012;307(23):2526-2533.

Ashbaugh

Bigelow

Petty

Levine

. Acute respiratory distress in adults. Lancet. 1967;2(7511):319-323.

Gattinoni

Caironi

Pelosi

Goodman

. What has computed tomography taught us about the acute respiratory distress syndrome? Am J Respir Crit Care Med. 2001;164(9):1701-1711.

Gattinoni

Pesenti

. The concept of “baby lung”. Intensive Care Med. 2005;31(6):776-784.

Gattinoni

Caironi

Cressoni

, et al. Lung recruitment in patients with the acute respiratory distress syndrome. N Engl J Med. 2006;354(17):1775-1786.

Gattinoni

Pesenti

Bombino

, et al. Relationships between lung computed tomographic density, gas exchange, and PEEP in acute respiratory failure. Anesthesiology. 1988;69(6):824-832.

Writing Group for the Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial (ART) Investigators, Cavalcanti

Suzumura

ÉA

, et al. Effect of lung recruitment and titrated positive end-expiratory pressure (PEEP) vs low PEEP on mortality in patients with acute respiratory distress syndrome: a randomized clinical trial. JAMA. 2017;318(14):1335-1345.

Hodgson

Cooper

Arabi

, et al. Maximal recruitment open lung ventilation in acute respiratory distress syndrome (PHARLAP). A phase II, multicenter randomized controlled clinical trial. Am J Respir Crit Care Med. 2019;200(11):1363-1372.

Grasselli

Calfee

Camporota

, et al. ESICM Guidelines on acute respiratory distress syndrome: definition, phenotyping and respiratory support strategies. Intensive Care Med. 2023;49(7):727-759.

10.

Amato

MBP

Meade

Slutsky

, et al. Driving pressure and survival in the acute respiratory distress syndrome. N Engl J Med. 2015;372(8):747-755.

11.

Briel

Meade

Mercat

, et al. Higher vs lower positive end-expiratory pressure in patients with acute lung injury and acute respiratory distress syndrome: systematic review and meta-analysis. J Am Med Assoc. 2010;303(9):865-873.

12.

Gattinoni

Coppola

Cressoni

Busana

Chiumello

. COVID-19 does not lead to a “typical” acute respiratory distress syndrome. Am J Respir Crit Care Med. 2020;201(10):1299–1300.

13.

Busana

Giosa

Cressoni

, et al. The impact of ventilation-perfusion inequality in COVID-19: a computational model. J Appl Physiol. 2021;130(3):865-876.

14.

Chiumello

Busana

Coppola

, et al. Physiological and quantitative CT-scan characterization of COVID-19 and typical ARDS: a matched cohort study. Intensive Care Med. 2020;46(12):2187-2196.

15.

Patel

Arachchillage

Ridge

, et al. Pulmonary angiopathy in severe COVID-19: physiologic, imaging, and hematologic observations. Am J Respir Crit Care Med. 2020;202(5):690-699.

16.

Perier

Tuffet

Maraffi

, et al. Effect of positive end-expiratory pressure and proning on ventilation and perfusion in COVID-19 acute respiratory distress syndrome. Am J Respir Crit Care Med. 2020;202(12):1713-1717.

17.

Pan

Chen

, et al. Lung recruitability in COVID-19-associated acute respiratory distress syndrome: a single-center observational study. Am J Respir Crit Care Med. 2020;201(10):1294-1297.

18.

Mauri

Spinelli

Scotti

, et al. Potential for lung recruitment and ventilation-perfusion mismatch in patients with the acute respiratory distress syndrome from coronavirus disease 2019. Crit Care Med. 2020;48(8):1129-1134.

19.

Beloncle

Pavlovsky

Desprez

, et al. Recruitability and effect of PEEP in SARS-CoV-2-associated acute respiratory distress syndrome. Ann Intensive Care. 2020;10(1):55.

20.

Herrmann

Mori

Bates

JHT

Suki

. Modeling lung perfusion abnormalities to explain early COVID-19 hypoxemia. Nat Commun. 2020;11(1):4883. https://www.nature.com/articles/s41467-020-18672-6

21.

Grasselli

Tonetti

Protti

, et al. Pathophysiology of COVID-19-associated acute respiratory distress syndrome: a multicentre prospective observational study. Lancet Respir Med England. 2020;8(12):1201-1208.

22.

Grieco

Bongiovanni

Chen

, et al. Respiratory physiology of COVID-19-induced respiratory failure compared to ARDS of other etiologies. Crit Care. 2020;24(1):529.

23.

Suter

Fairley

Schlobohm

. Shunt, lung volume and perfusion during short periods of ventilation with oxygen. Anesthesiology. 1975;43(6):617-627

24.

Fildissis

Katostaras

Moles

, et al. Oxygenation equilibration time after alteration of inspired oxygen in critically ill patients. Heart Lung. 2010;39(2):147-152.

25.

Weinreich

Thomsen

Hansen

Kjærgaard

Wagner

Rees

. Time to steady state after changes in FiO₂ in patients with COPD. COPD J Chronic Obstr Pulm Dis. 2013;10(4):405-410.

26.

Kassis

, et al. Titration of ventilator settings to target driving pressure and mechanical power. Respir Care. 2022;68(2):199-207

27.

Sarge

Baedorf-Kassis

Banner-Goodspeed

, et al. Effect of esophageal pressure-guided positive end-expiratory pressure on survival from acute respiratory distress syndrome: a risk-based and mechanistic reanalysis of the EPVent-2 trial. Am J Respir Crit Care Med. 2021;204(10):1153-1163.

28.

Hedenstierna

Edmark

. Mechanisms of atelectasis in the perioperative period. Best Pract Res Clin Anaesthesiol. 2010;24(2):157-169.

29.

Derosa

Borges

Segelsjö

, et al. Reabsorption atelectasis in a porcine model of ARDS: regional and temporal effects of airway closure, oxygen, and distending pressure. J Appl Physiol. 2013;115(10):1464-1473.

30.

Permutt

Bromberger-Barnea

Bane

. Alveolar pressure, pulmonary venous pressure, and the vascular waterfall. Med Thorac. 1962;19:239-260.

31.

Brower

Wise

Hassapoyannes

Bromberger-Barnea

Permutt

. Effect of lung inflation on lung blood volume and pulmonary venous flow. J Appl Physiol. 1985;58(3):954-963.

32.

Mitzner

Sylvester

. Hypoxic vasoconstriction and fluid filtration in pig lungs. J Appl Physiol Respir Environ Exerc Physiol. 1981;51(5):1065-1071.

33.

Santos

Ferrer

Roca

Torres

Hernandez

Rodriguez-Roisin

. Pulmonary gas exchange response to oxygen breathing in acute lung injury. Am J Respir Crit Care Med. 2000;161(1):26-31.

34.

Shapiro

Cane

Harrison

Steiner

. Changes in intrapulmonary shunting with administration of 100% oxygen. Chest. 1980;77(2):138–141.

35.

Ackermann

Verleden

Kuehnel

, et al. Pulmonary vascular endothelialitis, thrombosis, and angiogenesis in COVID-19. N Engl J Med. 2020;383(2):120-128.

36.

Gattinoni

Chiumello

Caironi

, et al.

COVID-19 pneumonia: different respiratory treatments for different phenotypes?

Intensive Care Med. 2020;46(6):1099-1102.

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

13.01 MB