Mechanical Ventilation in ARDS With an Automatic Resuscitator

Mayson LA Sousa; Bhushan H Katira; Doreen Engelberts; Vanessa Hsing; Annia Schreiber; Annemijn H Jonkman; Martin Post; Paul Dorian; Laurent J Brochard

doi:10.4187/respcare.10389

Mechanical Ventilation in ARDS With an Automatic Resuscitator

Respir Care. 2023 May;68(5):611-619. doi: 10.4187/respcare.10389. Epub 2022 Nov 11.

Authors

Mayson LA Sousa^{1

2

3}, Bhushan H Katira³, Doreen Engelberts³, Vanessa Hsing³, Annia Schreiber^{1

2}, Annemijn H Jonkman^{1

2}, Martin Post³, Paul Dorian⁴, Laurent J Brochard^{5

2

3}

Affiliations

¹ Keenan Centre for Biomedical Research, Critical Care Department, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada.
² Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada.
³ Translational Medicine Program, Research Institute, Hospital for Sick Children. University of Toronto, Toronto, Ontario, Canada.
⁴ Keenan Centre for Biomedical Research, Division of Cardiology, St Michael's Hospital, Toronto, Ontario, Canada.
⁵ Keenan Centre for Biomedical Research, Critical Care Department, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada. laurent.brochard@unityhealth.to.

Abstract

Background: The Oxylator is an automatic resuscitator, powered only by an oxygen cylinder with no electricity required, that could be used in acute respiratory failure in situations in which standard mechanical ventilation is not available or feasible. We aimed to assess the feasibility and safety of mechanical ventilation by using this automatic resuscitator in an animal model of ARDS.

Methods: A randomized experimental study in a porcine ARDS model with 12 pigs randomized to the Oxylator group or the control group (6 per group) and ventilated for 4 h. In the Oxylator group, peak pressure was set at 20 cm H₂O and PEEP was set at the lowest observed breathing frequency during a decremental PEEP titration. The control pigs were ventilated with a conventional ventilator by using protective settings and PEEP at the crossing point of collapse and overdistention, as indicated by electrical impedance tomography. Our end points were feasibility and safety as well as respiratory mechanics, gas exchange, and hemodynamics.

Results: After lung injury, the mean ± SD respiratory system compliance and P_aO₂ /F_IO₂ were 13 ± 2 mL/cm H₂O and 61 ± 17 mm Hg, respectively. The mean ± SD total PEEP was 10 ± 2 cm H₂O and 13 ± 2 cm H₂O in the control and Oxylator groups, respectively (P = .046). The mean plateau pressure was kept to < 30 cm H₂O in both groups. In the Oxylator group, the tidal volume was transiently > 8 mL/kg but was 6 ± 0.4 mL/kg at 4 h, whereas the breathing frequency increased from 38 ± 4 to 48 ± 3 breaths/min (P < .001). There was no difference in driving pressure, compliance, P_aO₂ /F_IO₂ , and pulmonary shunt between the groups. The mean ± SD P_aCO₂ was higher in the Oxylator group after 4 h, 74 ± 9 mm Hg versus 58 ± 6 mm Hg (P < .001). There were no differences in hemodynamics between the groups, including blood pressure and cardiac output.

Conclusions: Short-term mechanical ventilation by using an automatic resuscitator and a fixed pressure setting in an ARDS animal model was feasible and safe.

Keywords: artificial respiration; mechanical ventilators; rescue ventilation; respiratory distress syndrome; respiratory insufficiency; ventilator-induced lung injury.

MeSH terms

Animals
Lung
Positive-Pressure Respiration / methods
Respiration, Artificial* / methods
Respiratory Distress Syndrome* / therapy
Swine
Tidal Volume