1995 OPEN FORUM Abstracts
LAB EVALUATION OF NITRIC OXIDE DELIVERY VIA TRANSPORT VENTILATOR
John Newhart RCP CRTT, F. Wayne Johnson RCP, Richard N. Channick MD. UCSD Medical Center, San Diego, Ca.
The ability of inhaled nitric oxide (INO) to improve pulmonary hypertension and hypoxia has been previously described in the literature. At our institution INO has been utilized in selected patients with ARDS and pulmonary hypertension. Because some of these patients need to be transported to ancillary services, we devised a simple method of delivering INO via our transport ventilator. We evaluated the performance of this system in a laboratory setting. Background: Our transport systems are based on the Puritan Bennett Companion 2800 (2800) ventilator (Puritan Bennett, Lenexa Kansas) mounted on a specialy built cart to transport patients throughout the institution (Cates, Resp Prac, 88). The 2800 is a piston type home care/transport ventilator that has pediatric and adult capabilities. Oxygen enrichment is achieved by means of an internally baffled O2 accumulator attached to the gas intake.
Methods: We used nitric oxide (NO) 450ppm balance nitrogen as source gas. The NO cylinder was inserted into a fabricated holder that was attached to the transport cart. Attached to the NO cylinder is a stainless steel regulator (Puritan Bennett) and a 0-3 lpm flow meter. The NO was titrated via flow meter into the ventilator oxygen accumulator through a "Y" fitting. Pure oxygen from an "E" cylinder was introduced into the accumulator via the other branch of the "Y". A 0-15 lpm flow meter was used for O2 titration. Expired NO and Nitrogen Dioxide NO2 was scrubbed by passing the exhalate through a 4"x 20" acrylic cylinder filled with potassium permanganate pellets. This cylinder was attached to the transport cart. Analysis of inspired NO and (NO2) was via a API 200 Chemiluminescent analyzer (Advanced Pollution Instrumentation San Diego CA.) with the sample line at the ventilator outlet. Oxygen was analyzed with a MiniOx I (MSA Medical Products Pittsburg, PA) at the outlet port of the ventilator. The ventilator was attached to a Bio-Tek VT1 lung simulator (Bio-Tek Instruments Inc, Winooski VT). Ventilator settings were (Vt 1L, RR 15, Flow 60 LPM, PIP 22 cmH_2O, PEEP 0, Mode Control)
Results: By manipulating the NO and O2 flowmeters the following concentrations were delivered from the ventilator.
All values are flow rates expressed in LPM: NO, (O2)
NO Delivered 60% O280% O295% O2
NO 10PPM0.375 (7.5)0.375 (12) 0.5 (23)
NO 20PPM 0.875 (10) 0.875 (13) 1.5 (22)
NO 40PPM2.0 (10)2.125 (13) not possible
Conclusion: The highest inspiratory NO2 concentration measured was 0.3PPM. This is below the 5ppm OSHA Standard. Exhaled gas from the scrubber was NO 0PPM, NO2 0PPM. INO can be safely delivered and the exhalate scavenged while utilizing the Bennett 2800 ventilator, enabling transport of patients without interruption of INO.