Abstract
Background: In March of 2022 UC Davis Children’s Hospital NICU began utilizing first-intention HFJV with lung protective ventilation strategies in VLBW neonates < 29 wks. Often VLBW infants are intubated and transported from the delivery room. We strive to provide consistent, non-interrupted HFJV management. Transport of HFJV requires not only an external power source but mixed gases as well. Tank life is a limiting factor to transport. We performed bench testing on our transport capable HFJV with pneumatic conventional ventilator to inform time limits for safe transport.
Methods: For bench testing we established variables we hypothesized would most impact tank life. Jet PIP, jet frequency, jet PEEP, and FIO2 were identified as testing variables. E-cylinder air and oxygen tanks were measured at 2,000 psi beginning each test. We utilized a digital stopwatch to quantify time. All experiments utilized a 50 mL neonatal lung model. Pneumatic conventional ventilator flow setting was controlled at 10 L constant flow for all experiments. We controlled for all settings in each experiment except for the variable(s) in question (Table 1).
Results: The average time to empty when testing HFJV frequency was 63 min ± 4; no linear relationship identified with jet rate and time to empty. The average time to empty when testing jet PIP was 58 min ± 4; no linear relationship identified with jet PIP and time to empty. The average time to empty when testing HFJV PEEP was 60 min ± 2; no linear relationship identified with conventional PEEP and time to empty. FIO2 was tested at 0.21 and 0.50. Tank time to empty utilizing 0.21 experiment was 44 min and tank time to empty was 66 min utilizing 0.50.
Conclusions: Neither HFJV frequency, PIP or PEEP had an appreciable effect on tank time to empty during our bench testing. FIO2 had the largest effect on tank time to empty. It can be safely surmised that any PIP, PEEP, or frequency setting with a constant flow of 10 L, patients can be safely transported on full E-cylinder tanks with any FIO2 under 0.50 for at least 40 min. This serves as a good starting point for transporting neonates on HFJV and raises more questions regarding various FIO2 levels that were not tested in this bench experiment. Future testing with conventional constant flows less than and greater than 10 L is warranted. Although not reported here, battery life is also a limiting factor to transport time.
HFJV, pneumatic conventional ventilator, bench testing environment.
Footnotes
Commercial Relationships: Brian J Smith, MSc, RRT: Fisher Paykel; AARC
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