The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts


Matt McNally1, Harold Manning2; 1Respiratory Care, Dartmouth Hitchcock Medical Center, Lebanon, NH; 2Pulmonary Medicine, Dartmouth Hitchcock Medical Center, Lebanon, NH

Background: Any air leak in the patient-ventilator circuit may cause problems with ventilator triggering. In contrast to traditional pneumatic triggering, neurally adjusted ventilatory assist (NAVA) uses the electrical activity of the diaphragm (edi) to trigger and cycle a patient breath. Case: A 26 year old male with HIV/AIDS was admitted to the ICU with respiratory failure secondary to pneumocystis jirovecii pneumonia. The patientÂ’s course was complicated by bilateral pneumothoraces resulting in large air leaks. The air leaks caused false triggering of the ventilator that could be prevented only by making the trigger sensitivity so low that the patient was not able to trigger the ventilator at all. In order to tolerate the settings, the patient required large amounts of sedation (fentanyl at 1800 mcg/hr and midazolam at 20 mg/hr). These difficulties prompted us to proceed with a trial of NAVA utilizing a 16fr Edi catheter. With a NAVA level of 0.6 cm H2O/mv, the patient had an Edi Peak of 15, a respiratory rate of 6-10 breaths/min, and an inspired Vt of 600-650 ml. The exhaled Vt averaged only about 200 ml, which was well less than half the inspired Vt. On these settings, no false triggering was noted, and the patient tolerated a significant decrease in sedation. After 24 hours the patient was weaned to a t-piece CPAP at 7.5 cmH2O. Over the ensuing days, the patient alternated between CPAP and NAVA, with continued weaning of the patientÂ’s sedation. Over the following week the air leak subsided and the patient was able to remain on the CPAP valve continuously without an increase in Edi. Discussion: NAVA is a novel mode of ventilation that has the potential to enhance patient synchrony and comfort and reduce the need for sedation. However, there are no randomized, controlled trials of NAVA, and the literature consists of physiological studies involving small numbers of patients. Our experience with the patient presented here suggests that NAVA can be used effectively and safely to mechanically ventilate patients with large air leaks who are unable to be managed with conventional pneumatic triggering. We also found that Edi monitoring during the transition from the ventilator to CPAP and then to a trach collar provided valuable information. The Edi signal allowed the team to estimate the work of breathing and identify impending respiratory failure before there were indications from other physiologic signs. Sponsored Research - None