Blind Bronchoalveolar lavage. Patients were preoxygenated for 5-10 minutes with 100% oxygen and sterile, disposable swivel adapter was inserted between ETT tube and ventilator circuit. Thus, all the patients received ventilation during the procedure. The catheter used for performing the blind BAL was a balloon tipped wedge pressure catheter (Model A1- 07121, Arrow International, PA 19605, USA). This was 60cm in length, 4Fr, double lumen with inflatable balloon of 0.6 mL capacity at the distal end. The length of the catheter was primed and filled with saline before insertion. The catheter was introduced into the ETT tube via swivel adapter's small opening and advanced much further than the length of the ETT from the lip level till resistance met. To increase the chances of obtaining lavage from affected lung, head turning maneuver was used as described previously. The distal balloon was inflated with 1.0mL of normal saline since fluid is less compressible than air. Attempt was also made to wedge the catheter properly by further pushing it if possible. The volume of saline aliquot injected through catheter varied with the weight of the child. We used 3 mL for babies less than 5 Kg, 5 mL for children between 5 - 10 Kg, 7.5 mL for 11- 20 Kg and 10 mL for patients above 20 Kg. An aliquot of sterile saline was injected over 10 seconds and immediately reaspirated into the syringe attached to the 3-way of the catheter. Four such separate aliquots were used without withdrawing the catheter and using 4 different syringes. The first syringe aspirate was discarded while other 3 samples were collected in a sterile mucus trap.