Improved oxygenation in prone positioning of mechanically ventilated patients with COVID-19 acute respiratory distress syndrome is associated with decreased pulmonary shunt fraction: a prospective multicenter study

Piotr Harbut; Francesca Campoccia Jalde; Martin Dahlberg; Anders Forsgren; Elisabeth Andersson; Andreas Lundholm; Jaroslaw Janc; Patrycja Lesnik; Michal Suchanski; Pawel Zatorski; Janusz Trzebicki; Tomasz Skalec; Mattias Günther

doi:10.1186/s40001-023-01559-9

Improved oxygenation in prone positioning of mechanically ventilated patients with COVID-19 acute respiratory distress syndrome is associated with decreased pulmonary shunt fraction: a prospective multicenter study

Eur J Med Res. 2023 Dec 16;28(1):597. doi: 10.1186/s40001-023-01559-9.

Authors

Affiliations

¹ Department of Clinical Sciences Danderyd, Karolinska Institutet, Stockholm, Sweden.
² Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
³ Department of Perioperative Medicine and Intensive Care, Thoracic Anesthesia and Intensive Care Unit, Karolinska University Hospital, Stockholm, Sweden.
⁴ Department of Clinical Science and Education Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.
⁵ Department of Clinical Science and Education Södersjukhuset, Section for Anesthesiology and Intensive Care, Karolinska Institutet, Sjukhusbacken 10, SE-118 83, Stockholm, Sweden.
⁶ 4th Military Clinical Hospital, Wroclaw, Poland.
⁷ Medical University of Warsaw, Warsaw, Poland.
⁸ Wroclaw Medical University, Wroclaw, Poland.
⁹ Department of Clinical Science and Education Södersjukhuset, Section for Anesthesiology and Intensive Care, Karolinska Institutet, Sjukhusbacken 10, SE-118 83, Stockholm, Sweden. mattias.gunther@ki.se.

Abstract

Background: Prone position is used in acute respiratory distress syndrome and in coronavirus disease 2019 (Covid-19) acute respiratory distress syndrome (ARDS). However, physiological mechanisms remain unclear. The aim of this study was to determine whether improved oxygenation was related to pulmonary shunt fraction (Q's/Q't), alveolar dead space (Vd/Vtalv) and ventilation/perfusion mismatch (V'_A/Q').

Methods: This was an international, prospective, observational, multicenter, cohort study, including six intensive care units in Sweden and Poland and 71 mechanically ventilated adult patients.

Results: Prone position increased PaO₂:FiO₂ after 30 min, by 78% (83-148 mm Hg). The effect persisted 120 min after return to supine (p < 0.001). The oxygenation index decreased 30 min after prone positioning by 43% (21-12 units). Q's/Q't decreased already after 30 min in the prone position by 17% (0.41-0.34). The effect persisted 120 min after return to supine (p < 0.005). Q's/Q't and PaO₂:FiO₂ were correlated both in prone (Beta -137) (p < 0.001) and in the supine position (Beta -270) (p < 0.001). V'_A/Q' was unaffected and did not correlate to PaO₂:FiO₂ (p = 0.8). Vd/Vtalv increased at 120 min by 11% (0.55-0.61) (p < 0.05) and did not correlate to PaO₂:FiO₂ (p = 0.3). The ventilatory ratio increased after 30 min in the prone position by 58% (1.9-3.0) (p < 0.001). PaO₂:FiO₂ at baseline predicted PaO₂:FiO₂ at 30 min after proning (Beta 1.3) (p < 0.001).

Conclusions: Improved oxygenation by prone positioning in COVID-19 ARDS patients was primarily associated with a decrease in pulmonary shunt fraction. Dead space remained high and the global V'_A/Q' measure could not explain the differences in gas exchange.

Keywords: Acute respiratory distress syndrome; COVID-19; Intensive care; Prone position; Pulmonary shunt fraction.

Publication types

Observational Study
Multicenter Study

MeSH terms

Adult
COVID-19* / therapy
Cohort Studies
Hemodynamics
Humans
Prone Position
Prospective Studies
Pulmonary Gas Exchange / physiology
Respiration, Artificial
Respiratory Distress Syndrome* / therapy