A clinical study of significance of diffusion hypoxia after general anaesthesia with nitrous oxide and oxygen

Dr. Jonanalagadda Venkata Subba Rao; Dr. Syeda Huma Gulbadeen; Dr. G Raghavendra Prasad

Volume : VIII, Issue : V, May - 2018

A clinical study of significance of diffusion hypoxia after general anaesthesia with nitrous oxide and oxygen

Dr. Jonanalagadda Venkata Subba Rao, Dr. Syeda Huma Gulbadeen, Dr. G Raghavendra Prasad

Abstract :

Introduction: At the end of general anaesthesia rapid excretion of nitrous oxide into the alveoli dilutes the oxygen concentration in the alveoli . Breathing that hypoxic mixture will result in diffusion hypoxia. Administration of 100% oxygen after extubation will reverse this hypoxia . We carried out a clinical study to test the above hypothesis

Material and Methods : We have taken 44 young healthy patients and allocated them into two groups . Group l patients were given 100% oxygen for 5 minutes. Patients in group ll were allowed to eathe room air after extubation . Oxygen saturation of all patients was assessed with pulse oximetry every minute for fifteen minutes after extubation. Pulse rate and respiratory rate was also observed at the same intervals.

Results : We observed that in patients who eathed room air after extubation , there was a 2 to 3% fall of oxygen saturation compared with pre op saturation . None of the patients had clinically significant hypoxia .There was no fall of oxygen saturation in patients who were given 100% oxygen. When the fall of oxygen saturation in patients who eathed room air was compared with the oxygen saturation of patients who received 100% oxygen the fall of saturation was statistically significant . None of the patients had alterations in pulse or respiratory rate in relation to oxygen saturation.

Conclusions : We conclude that clinically significant hypoxia does not occur in young healthy patients after nitrous oxide anaesthesia. Five minute oxygen administration after extubation may not be required in young healthy patients