The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts


Jay Zignego1, Robert M. DiBlasi1,2, Stewart Carlson1, Kathleen Bongiovanni1, Thomas Hansen1, Peter Richardson1,3

Background: Worldwide, nearly four million infants die each year due to birth asphyxia and prematurity. Many deaths in resource-limited regions are related to inadequate medical training and lack of simple equipment. Recently, concerns about mass casualty respiratory failure scenarios have led to increased awareness of ventilator stockpiles in preparation for a surge capacity situation. Performance characteristics for ventilators are not well defined for infants <5 kg and it is unclear whether current stockpiles of ventilators would prove efficacious in this population. We designed an inexpensive (< $100) time-cycled pressure-limited (TCPL) infant ventilator to be simple to operate with very few moving or difficult to replace components. This device functions by cycling between PIP and PEEP circuits submerged to a specified depth within a water column. A pinch exhalation valve controls the rate and timing of the inflations and a constant flow of blended gas is supplied at the airway. The patient is able to breathe spontaneously between ventilator delivered inflations. In addition, the bubbling created by gas exiting the exhalation circuit could provide physiologic advantages when recruiting diseased lung units. We hypothesized that this ventilator could be suitable for resource-limited and surge capacity circumstances.

Methods: We confirmed the function of this device using an infant lung model of respiratory distress. We configured the lung model (ASL 5000) with CL-0.6 mL/cmH2O and RAW-100 cmH2O/L/s. We connected a rigid low-compliance (reusable) circuit to the lung model via a 2.5 mm ETT. The ventilator was set to deliver PIP/PEEP of 16/6 cmH2O, TI -0.3s, and frequency of 60 breaths/min. The lung model was ventilated using this device and compared to a Galileo microprocessor ventilator (Hamilton Medical, Reno NV) and measurements were obtained under identical settings and experimental conditions. Paw and volume delivered to the lung model were measured for 17s with a pressure transducer and a flow sensor connected to an A/D converter sampling at ~1 kHz.

Results: The figure shows a comparison between the TCPL device and the Hamilton ventilator. The Paw and delivered volumes were similar in both devices with the exception of the pressure oscillations seen during exhalation in the TCPL ventilator.

Conclusion: Future studies have been designed which will focus on evaluating the effect of this ventilator on gas exchange in animal models to determine efficacy.