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 PaO2/FIO2 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, PaO2/FIO2, and pulmonary shunt between the groups. The mean ± SD PaCO2 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.
- artificial respiration
- mechanical ventilators
- respiratory insufficiency
- ventilator-induced lung injury
- respiratory distress syndrome
- rescue ventilation
Footnotes
- Correspondence: Laurent J Brochard MD, Keenan Research Centre - St. Michael's Hospital, Unity Health Toronto, Li Ka Shing Knowledge Institute, 4th Floor, Room 411, 209 Victoria Street, Toronto, ON, M5B 1T8 Canada. E-mail: laurent.brochard{at}unityhealth.to
The authors have disclosed no conflicts of interest.
This work was supported by a grant from the University of Toronto (Toronto COVID-19 Action Initiative – Connaught/ISI (Dr Dorian), a MITACS Accelerate Training Grant (Dr Dorian), and Canadian Institutes of Health Research (PJT 156336 to Drs Post and Brochard).
Supplementary material related to this paper is available at http://www.rcjournal.com.
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