A Gas-Powered, Patient-Responsive Automatic Resuscitator for Use in Acute Respiratory Failure: A Bench and Experimental Study

Abstract

Background: During the COVID-19 pandemic, a need for innovative, inexpensive, and simple ventilator devices for mass use has emerged. The Oxylator is an FDA approved, fist-size, ultra-light, portable ventilation device developed for out-of-hospital emergency ventilation. It has not been tested in conditions of severe lung injury or with added PEEP. Objectives: 1) To assess the performance and reliability of the device in simulated and experimental conditions of severe lung injury, and 2) to derive monitoring methods allowing the delivery of a safe individualized ventilation during situations of surge. Methods: Functioning of the device with added PEEP valve was extensively tested on a bench, mimicking adult patients with various respiratory mechanics during controlled ventilation, spontaneous breathing, and prolonged unstable conditions where mechanics and/or breathing effort was changed at every breath. The device was further tested on a porcine model (n=4) with normal lungs and after inducing lung injury and was compared with conventional ventilation modes. Results: The device was stable and predictable: it delivered a constant flow (30 L/min) and cycled automatically at the inspiratory pressure set (minimum of 20 cmH 2 O) above auto-PEEP. Changes in respiratory mechanics manifested as changes in respiratory timing, allowing prediction of tidal volumes from respiratory rate. Simulating lung injury resulted in relatively low tidal volumes (330 mL with compliance of 20 mL/cmH 2 O). In the porcine model, arterial oxygenation, CO 2 and pH were comparable to conventional modes of ventilation. Conclusion: The Oxylator is a simple device that delivers stable ventilation with tidal volumes within a clinically acceptable range in bench and porcine lung models with low compliance. External monitoring of respiratory timing is advisable, allowing tidal volume estimation and recognition of changes in respiratory mechanics. The device can be an efficient, low-cost practical rescue solution for providing ventilatory support as a temporary bridge but requires a caregiver at bedside.

The eSpiro Ventilator: An Open-Source Response to a Worldwide Pandemic

“…The huge flow rate of patients with a severe acute respiratory failure admitted to ICUs worldwide during the first wave of the COVID-19 pandemic created a risk of ventilators shortage and urged the healthcare system to quickly implement different strategies to match the demand [ 1 , 10 ]. Strategies of note included splitting ventilators between two patients [ 11 , 12 ], developing easy-to-build, open-source, cheap ventilators [ 13 , 14 ] and using an intermediate ventilator dedicated to emergency rooms and patient transport with an enhanced production at a large scale with the help of non-medical industry. Using the same ventilator for two patients is still an experimental and non-recommended strategy [ 11 ].…”

“…Using the same ventilator for two patients is still an experimental and non-recommended strategy [ 11 ]. Jonkman et al have proposed a gas-powered, patient-responsive automatic resuscitator for use in acute respiratory failure [ 14 ]. Even if they demonstrated in a bench and porcine model that the device can be efficient, it requires a caregiver at the bedside.…”

Reply: Ventilator Options for COVID-19: Quality Trumps Quantity

“…We further agree with their nuanced categorization of the oxylator and GO2VENT as automatic resuscitators rather than ventilators. Similar to anesthesia machines, they require the constant presence of an operator ( 2 ), lack the capabilities of a typical ICU ventilator, and lack the alarms or sophisticated monitoring that a typical ICU ventilator has, as we discussed in our manuscript and as Drs. Branson and colleagues further elaborate on in their response.…”

“…As we carefully caveated in this section, these devices are essentially last-line options for very specific cases and may serve as bridges until better supply arrives. The oxylator device is described in the same manner in the paper by Jonkman and colleagues highlighted by the authors ( 2 ). Such a scenario may be a hospital setting where all invasive and noninvasive measures are in use or awaiting transition and/or cleaning while further patients require immediate invasive ventilation.…”

Ventilator Options for COVID-19: Quality Trumps Quantity

“…Jonkman and colleagues have recently evaluated the oxylator, characterizing its performance and concluding that short term attended use is the only safe application ( 3 ). Previous work by Babic and colleagues demonstrated routine, unannounced failure of the Vortran resuscitator associated with changes in device position ( 4 ).…”