Abstract
Background:
Military transport of critically ill/injured patients requires judicious use of resources. Maintaining oxygen (O2) supplies for mechanically ventilated is crucial. O2 cylinders are difficult to transport and add the risk of fire in an aircraft. The proposed solution is the use of a portable oxygen concentrator (POC) to supply O2 for mechanical ventilation. As long as power is available, a POC can provide a continuous supply of O2. Evidence suggests that 3 L/min of O2 could manage 2/3 of the mechanically ventilated aeromedical transport patients.
Methods:
We evaluated two each of the AutoMedx SAVe II, Hamilton T1, Zoll 731,and one Ventec VOCSN portable ventilator over a range of settings paired with two Caire SAROS POCs. The VOCSN operates from an internal O2 concentrator using pulsed dose delivery equivalent to 6 L/min continuous flow O2. Each ventilator was attached to one chamber of a Michigan Instruments Training Test Lung (TTL). Output from the POC was bled-in to each ventilator via the mechanism provided. A Fleisch pneumotach was placed between the ventilator circuit and the TTL to measure delivered tidal volume (VT) and a fast response O2 analyzer (Oxigraf) sampled gas from the TTL to measure FIO2. Deadspace was added between the ventilator circuit and TTL for pulsed dose delivery. Ventilator parameters and FIO2 were continuously measured and recorded for later analysis. One-way ANOVA was used to determine statistically significant differences (P < .05) in FIO2 at each ventilator/POC setting.
Results:
Delivered FIO2 varied widely between ventilator models and between devices of the Hamilton T1 ventilators. Differences in FIO2 at each ventilator/POC setting was statistically significant (P < .05) but not all were clinically important. The SAVe II delivered the highest FIO2 at all conditions using a VT of 700 mL owing to limited VE capabilities. The highest delivered FIO2 was 84.6% ± 0.5 at the 250 mL VT settings using 2 POCs (P < .001). The Zoll 731 delivered the highest FIO2 at each ventilator setting using both POCs. Calculated FIO2 displayed on the VOCSN in pulsed dose mode was within ± 2% absolute of measured FIO2.
Conclusions:
Oxygen delivery utilizing POCs is dependent upon multiple factors including ventilator operating characteristics, ventilator settings, and the use of pulsed dose or continuous flow O2. Careful patient selection would be paramount to provide safe mechanical ventilation using this method of O2 delivery.
Measured FIO2 for the 250 mL VT settings at all conditions. *VOCSN internal oxygen concentrator with pulse dose settings equivalent to 1 and 2 SAROs POCs. View all access options for this article.
Ventilator Settings
731
SAVe II
T1
VOCSN
*VOCSN Int
RR30/VT250/PEEP5/CL80/1POC
51.0 ± 0.7
49.7 ± 0.6
43.0 ± 2.3
35.5 ± 0.1
34.0 ± 0.4
RR30/VT250/PEEP5/CL80/2POC
84.7 ± 0.5
72.7 ± 0.2
65.8 ± 7.2
51.2 ± 0.3
45.3 ± 0.5
RR30/VT250/PEEP20/CL20/1POC
50.7 ± 0.5
45.5 ± 0.3
43.1 ± 3.7
35.9 ± 0.1
32.0 ± 0.1
RR30/VT250/PEEP20/CL20/2POC
84.4 ± 0.5
72.7 ± 0.3
64.2 ± 10.3
52.3 ± 0.1
43.2 ± 0.1
Get full access to this article