1170

Abstract

Introduction: Approximately 15–20% of deaths occurring in patients with severe hypoxemic respiratory failure i.e. PaO2/FIO2 < 100, results from refractory hypoxemia in those failing conventional mechanical ventilation strategies. We present a case of severe hypoxemic respiratory failure in which conventional modes of treatment failed to improve oxygenation. Hypothesis: Patient is a 35 year old female admitted to the ICU from the OR. She had been scheduled to undergo genitourinary surgery but developed severe laryngospasm prior to the procedure, resulting in fiber optic intubation. Patient developed hypotension and subsequent 1 liter fluid resuscitation resulted in flash pulmonary edema. Her oxygenation continued to rapidly deteriorate despite diuresis and optimal ventilatory support on AC/VC ventilation: tidal volume 6mL/kg IBW, RR-24, PEEP 20 cmH2O and FIO2 1.0. An ABG revealed the following: pH 7.28, PaCO2 38, PaO2 38, SaO2 65% and HCO3 17.7 Methods: The patient was subsequently placed on high frequency percussive ventilation (HFPV): percussive rate 600/min, convective rate 15/min, oscillatory CPAP 14 cmH2O and FIO2 1.0. Within an hour, an ABG revealed the following: pH-7.44, PaCO2 24, PaO2 65, SaO2 -94% and HCO3 15.9, with further improvements in subsequent serial ABGs. The patient remained on HFPV for 2 days before being switched to AC/VC ventilation. She was extubated on the 4th day of ICU admission and successfully discharged home on the 8th day of hospital stay. Results: HFPV delivers pressure limited, flow-regulated and time-cycled breaths via the volumetric diffusive respirator (VDR). It delivers a series of high-frequency (200-900 cycles/min) small volumes in a successive stepwise stacking manner that results in the formation of low-frequency convective pressure-limited breath cycles. This unique mode uses various mechanisms of gas exchange to enhance oxygenation and ventilation. In addition, the use of oscillatory CPAP further improves oxygenation through enhanced diffusion. Conclusions: High frequency percussive ventilation is a useful modality in the treatment of severe hypoxemic respiratory failure when conventional ventilatory strategies fail to achieve the necessary goals in oxygenation and ventilation.