2004 OPEN FORUM Abstracts
THE iNOVENT INJECTOR IN HIGH FREQUENCY JET VENTILATION, A BENCH STUDY.
Richard M. Hoskins RRT C-CPT CPFT Christus St Joseph Hospital NICU, Houston Texas
Background: Very few references are available on the safe and efficacious use of Inhaled Nitric Oxide (iNO) with High Frequency Jet Ventilation (HFJV) iNOthereapueutics has described in their technical bulletin that the use of the iNOVent (INOTherapeutics) is not approved for use with the Bunnell Life Port HFJV (Bunnell Inc) due to some cases in that the jet servo pressure may exceed 6 PSI, which is beyond the safe operating pressure for the iNOVent Injector module. Platt et al, has described a method of using the iNOVent Injector with HFJV (J.of Perinatology 2003; 28:287-291, and personal communication) in that the injector module is placed proximal to the humidification module of the HFJV, for more accurate delivery of iNO.
Study Question: Can the iNOVent Injector module be used with the Bunnell HFJV without exceeding the operational pressures of the injector as outlined by the iNOVent Operators Manual?
Method: A HFJV/ iNO system was constructed as outlined in the study described by Platt et al, using an iNOVent system, a Bunnell HFJV, and a Sechrist IV 100B Infant Ventilator. An RT-200 Calibration Analyzer (Timeter Corp) was used to verify the pressures observed in the iNOVent Injector. The injector was inserted in the Gas Out line proximal to the Humidifier module of the HFJV, Two 4.5 mm ETT adapters and a 22mm/15mm adapter was used to connect the HFJV Gas Out tubing to the Injector module. Various ventilatory scenarios of PIP and PEEP, and with and without Conventional Ventilation (CV) breaths. Compliance of the test lungs was also changed to determine if increased resistance would increase the Servo Pressure, and thereby increase the pressures in the Injector Module. Observation of the pressures obtained by the RT-200, compared to the pressures displayed on the Servo Pressure displayed on the HFJV was noted. That the Servo Pressures reflect the actual pressures in the Gas Out line, was confirmed in communication with the technical support of Bunnell Inc. (D.Platt, personal communication) Ventilatory scenarios were set for our patient population. (urban level III NICU) using observed data from previous patient records. In our level III NICU, we have not observed instances of the servo pressureexceeding 5 PSI, in our patient population.
Conclusion: In this bench study we have observed that the Servo Pressure as displayed on the Bunnell HFJV closely correlates with measured pressures within the Gas Out line proximal to the HFJV humidifier. We have concluded that the application of iNO with HFJV, as described by Platt et al, can be administered without violating the operating parameters as outlined by iNOTherapeutics in their Technical Bulletin, as long as the Servo Pressure is monitored and remains below 6 PSI. We have not attempted to test this system in a larger or pediatric population model.