Study to compare pressure support ventilation and T-piece as strategies of spontaneous breathing trials for weaning in ICU

Spontaneous breathing trial is a method to identify readiness of extubation by incorporating a technique which allows gradual decrease in mechanical support of ventilator. SBT can be conducted by different methods like T-piece breathing, low level pressure support ventilation with or without PEEP, low level continuous airway pressure and flow trigger with no pressure applied to airway. There are some advanced methods of SBT like closed-loop systems with intelligent modes, adaptive support ventilation (ASV), neurally adjusted ventilatory assist (NAVA), and proportional assisted ventilation (PAV). Low level PSV and T piece are most common methods used for SBT. Low level PSV includes a pressure of upto 8 cm H2O in adults and upto 10 cm H2O in pediatric patients. In T-piece trial, patients are disconnected from ventilator and put on t-tube with oxygen support of 9-11 litres /min. SBT can be given for 30 to 120 minutes and after that success of trial can be monitored using subjective and objective criteria.

Depending on success of these SBTs, weaning can be classified further according to different classifications to assess success of weaning. We will be using WIND criteria. According to the success of SBT patients will be classified in following four weaning groups: 1. Group NW: patients who never experienced any separation attempt (SA); 2. Group 1: the first SA resulted in termination of the weaning process within 1 day 3. Group 2: weaning was completed after more than 1 day but in less than 1 week after the first SA 4. Group 3: weaning was not terminated by 7 days after the first SA Patients who will not be weaned off after 7 days will be regarded as failure of weaning.