Case Report - Pressure Controlled Inverse Ratio Ventilation in Acute Respiratory Distress Syndrome Patients

Appropriate ventilatory intervention is life saving in acute respiratory distress syndrome (ARDS). Pressure controlled inverse ratio ventilation (PC-IRV) is the likely mode of ventilation benefiting in extreme conditions of ARDS. However, guidelines when to start PC-IRV are not yet well defined. The ventilation-related dilemma, which we faced in two illustrative cases of ARDS are presented. The first patient presenting clinically with ARDS but with high peak airway pressure (PIP) and low dynamic lung compliance, PC-IRV helped in reducing PIP, improved haemodynamics and the oxygenation of blood. In second patient with similar clinical presentation of ARDS, where although PIP was high but the dynamic compliance was better, the PC-IRV caused deterioration in PaO₂. Here, patient rather did better with high PEEP (15cmH₂O) and usual I:E ratio (1:2). It is probable that the dynamic lung compliance (<20ml/cmH₂O), PIP (>50cmH₂O) at conventional I:E ratio (1:2) ventilation (10ml/kg) with hypotension might form the basis to develop a scoring system for guidance to switch over to PC-IRV ventilation. Further randomised prospective controlled clinical trials will then be required to establish indication to start PC-IRV in ARDS.

Keywords
ARDS, Pressure controlled ventilation, Inverse ratio ventilation, PC-IRV, Positive pressure ventilation