Aim : To evaluate the relative success rates of PC-BIPAP (pressure controlled bilevel positive airway pressure) mode with mechanical ventilators versus AVAPS mode (average volume assured pressure support) of conventional BiPAP in patients of hypercapnic respiratory failure.

Method : Single center, unblinded, randomised control trial conducted at Intensive care unit of a tertiary care hospital in India. Fifty patients of hypercapnic respiratory failure arterial pH between 7.15-7.25, fulfilling the inclusion criteria were randomised (1:1) to recieved Non-invasive ventilation (NIV) though mechanical ventilators or conventinal BiPAP. They were followed up till outcome defined as intubation or arterial pH>7.35 or pCO2>55mmHg.

Results : Sixty two patients were enrolled, 25 assingned to each group. Treatment failure of NIV
occurred in 8% of patients in Ventilator group and 12% of patients in BiPAP group (p=0.667).COPD patient without co-morbidities had most favorable outcome.ABG parameters at admission do not determine the outcome for arterial pH range (7.15-7.25). The change in pH and pCO2 after 2 hours of NIV predicted the favorable outcome (p<0.001).

Conclusion : NIV trial with either mechanical ventilator or conventional BiPAP can be given in all spontaneously breathing patients of hypercapnic failure if there are no contraindications. An ICU setup and trained staff for intubation are must before considering NIV.