ABSTRACT:Preoxygenation is a procedure done to prolong safe period of apnoea from induction of anaesthesia till the airway is secured by increasing the oxygen stores of functional residual capacity of lungs. It is of paramount importance when difficulty in ventilation and/or endotracheal intubation is anticipated e.g. in pregnant and obese patients. Here, we tried to find out a better technique of preoxygenation in obese patients.

METHODS : Sixty ASA grade I/II, obese grade 1 (30-34.9 Kg/m2) adults were randomized into two groups to receive 100% oxygen before induction of anaesthesia - Group A (to breathe normal tidal volume over 5 minutes at flow rate of 5 L/min) and group B (to breathe eight vital capacity breaths over 1 minute at flow rate of 10 L/min). Each technique was evaluated by end tidal oxygen concentration (EtO2) at end of preoxygenation and time to desaturateupto 95% (T95).

RESULTS : In groups A and B the EtO2 values were 88.4 ± 2.48 and 88.1 ± 2.10 (p value>0.05); and T95 values were 189.53 ± 17.44 and 179.30 ± 16.50 (p value<0.05) respectively.

CONCLUSIONS : We concluded that tidal volume breathing for 5 min is better technique of preoxygenation in obese (grade 1) patients compared to 8 vital capacity breaths as the former gives significantly more time to desaturateupto 95%.