The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts


Ashley Thompson, Edward Schneider, Grant D. Wilson; Respiratory Care, Mayo Clinic, Rochester, MN

Background: Oxygen planning for fixed wing transport includes 3 parts: preflight estimate of patient needs, patient contact actual oxygen needs, and in-flight monitoring of oxygen usage. The LTV 1200 ventilator has an internal Oxygen Cylinder Duration Calculator that is useful for predicting available oxygen time when a patient is connected to the device; however, medical transport teams must predict oxygen usage prior to patient contact before departing toward the referral center. Goal: Develop a formula for preflight oxygen planning for the LTV 1200 ventilator. Methods: We tested the Viasys LTV 1200 ventilator in a number of patient scenarios, pediatric to adult, to confirm the oxygen consumption of the device is as indicated in the manufacturer’s specifications. For each scenario, the ventilator was attached to a test lung with a fixed inspired minute volume and 100% O2; the cylinder size and pressure were entered into the ventilator’s Oxygen Cylinder Duration Calculator and the resulting calculated tank duration recorded. The ventilator was then attached to an oxygen E cylinder and monitored for time until the ventilator failed to cycle. Results: The LTV 1200 ventilator’s specifications list a bias flow of 10 L/min that is active during the expiratory phase only. For the invasive ventilation scenarios, we found the ventilator consumed 7 to 8 L/min. of oxygen (dependent on I:E ratio) in addition to the inspired minute volume. When attached to a full E cylinder (707 Liters) the ventilator calculated cylinder duration at 71 minutes and had a measured duration of 78 minutes. The non-invasive simulations varied considerably with oxygen usage calculated as high as 30 L/min. with a modest mask leak. Conclusions: The LTV 1200 ventilator consumes oxygen at a predictable rate consistent with its specifications when used invasively and in a controlled mode; the LTV 1200’s internal Oxygen Cylinder Duration Calculator is fairly accurate, underestimating available oxygen slightly in the scenarios tested. Oxygen usage during Non-invasive ventilation with the LTV 1200 is not predictable, with consumption rates as high as 30 L/min. in the scenarios tested. For preflight oxygen planning when the internal calculator is not available, the formula: Inspired Minute Volume + 10L/min., for intubated patients, should provide a margin of safety that can be confirmed after the patient is attached. Sponsored Research - None