A Bay of Plenty truck driver says he felt like a human balloon when compressed air was forced into his body after he fell onto a brass fitting that pierced his buttock.



Despite the freak accident, Opotiki's Steven McCormack, 48, was cheerful in Whakatane Hospital's intensive care unit yesterday, saying he felt "lucky to be alive".



On Saturday he was standing on the plate between the cab of his truck and semi-trailer at Waiotahi Contractors.



His foot slipped and, as he fell, he broke the hose off a brass nipple connected to the compressed air reservoir powering the truck's brakes.



He fell hard on to the nipple, which pierced the flesh of his left buttock.



As the air, compressed to 100 pounds per square inch, began rushing into his body and he started screaming.



"I felt the air rush into my body and I felt like it was going to explode from my foot," McCormack said.



"I was blowing up like a football... it felt like I had the bends - like in diving. I had no choice but just to lay there, blowing up like a balloon."



Doctors later told him that the air separated fat from muscle, and they were surprised it did not break his skin.



McCormack's workmates heard his screams and found him with the elbow-shaped nipple hooked into his rear, company co-owner Robbie Petersen said.



He said he could hear the air hissing out and quickly released the pressurised container's safety valve to stop the air flow.



The nipple remained embedded as three men - Jason Wenham, Ross Hustler and Petersen - lifted McCormack's upper torso on to the truck's plate.



Wenham put him on his side in the recovery position, a move McCormack thought probably saved his life.



It helped him breathe, although his head and neck were swollen and one lung was filling with fluid.



His workmates broke into a water cooler to find ice, which they packed around his neck to ease the swelling.



They waited an hour for ambulances to arrive from Whakatane as Opotiki's ambulance and the rescue helicopter were busy.



Aided by a doctor, ambulance officers removed the nipple and McCormack was rushed to Whakatane Hospital.



Doctors inserted a tube into his lungs to drain the fluid and cleared the wound in his buttock using what felt to him like a drill. "That was the most painful part."



He said his skin felt "like a pork roast" - crackling on the outside but soft underneath. The only way for the air to escape was the usual way gas passed from the body, he said.



He credited his workmates - Wenham especially - with saving his life and thanked emergency services and hospital staff for their actions.



He also thanked his family for their support.



Petersen said it was a "million-to-one freak accident" and he had notified the Department of Labour.



The surgeon who treated McCormack declined to be interviewed.