1236 A Challenging Transition Between Volume Assured Modes in a Patient with Congenital Lung Abnormalities

Abstract Introduction The advent of volume-assured modes for non-invasive ventilation (NIV) has improved treatment of more complicated sleep-disordered breathing (SDB), although can present challenges in choosing ventilatory modes in patients with abnormal pulmonary anatomy. Report of case(s) Our Patient is a 44 year-old female with hypoplastic right lung, pulmonary hypertension and chronic hypercapnic/hypoxic respiratory failure on nocturnal NIV for complex sleep disordered breathing. She failed CPAP, BIPAP and BIPAP S/T. Average volume assured pressure support (AVAPS) NIV was initiated with stabilization in awake carbon dioxide levels, improved sleep quality and daytime energy . She was transitioned to an iVAPS (intelligent volume-assured pressure support) ventilator when eligible for new NIV. Initial settings were empiric, targeting Alveolar Ventilation 3.3 l/min to approximate similar minute ventilation set on previous AVAPS (Assumed dead space ventilation 1.05 l/min or 70 cc x 15rr). Despite relatively similar recorded pressures and respiratory parameters between the two volume-targeted ventilators, she experienced air hunger, palpitations and increased morning headaches after change from AVAPS to iVAPS. Alveolar ventilation target was increased to 4.5 l/min, yet symptoms persisted. She subsequently returned to AVAPS, with symptom resolution. Conclusion This case highlights the uncertainty in transitioning volume assured ventilator modes that use different algorithms to achieve ventilatory targets. We hypothesized incorrect dead space estimates in the setting of her abnormal pulmonary anatomy may lead to inequivalent respiratory targets between modes, but this does not appear to be the case based on available data. The sensation of dyspnea is complex, thus it is possible subtle changes in rise time, breath delivery, cycling and triggering may have contributed to air hunger. Furthermore, many assumptions are made when transitioning between intelligent ventilator modes and these assumptions are based on “normal” respiratory dynamics. Support (if any) Note- Chart would not transfer, abbreviated data placed below. Settings- (both modes) EPAP 6, Min ipap 17, max IPAP 30 AVAPS- Tidal volume 300, T insp max 2 second, rise time 200 ms iVAPS- Alveolar ventilation 3.3 l/min, T insp max 2 sec, rise time 200 ms Outcome AVAPS- RR 14-15, TV 301-313, MV 4.3, IPAP 20.6, triggered 36% iVAPS- RR 15-32, TV 300-480, MV 4.5, IPAP 20.6, Triggered 30%