Publication: Effect of Positive Airway Pressure During Preoxygenation on Safe Apnea Period: a comparison of the supine and 25° head up position
Date
2020
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Kathmandu University
Abstract
ABSTRACT
Background
Preoxygenation is performed before induction of anaesthesia which increases oxygen
reserve and provides delayed onset of hypoxia during period of apnea. Several
techniques such as positive airway pressure and head-up tilt during preoxygenation
have shown to prolong safe apnea period compared to conventional technique.
However, uniform recommendations have not yet been made.
Objective
To find out the effect of combination of 5 cmH2O continuous positive airway pressure
(CPAP) and 25° head up position during preoxygenation on safe apnea period.
Method
In this comparative study 60 non-obese adult patients were divided into three
equal groups; Group C receiving preoxygenation in conventional technique, Group
S receiving preoxygenation with 5 cmH2O continuous positive airway pressure in
supine position and Group H receiving preoxygenation in 25° head-up position
with 5 cmH2O continuous positive airway pressure . After 3 min of preoxygenation,
intubation was performed after induction of anaesthesia with propofol, fentanyl and
succinylcholine. After confirming the tracheal intubation by direct visualization, all
patients were administered vecuronium to maintain neuromuscular blockade. Post-
intubation, patients in all groups were left in same position with the tracheal tube
exposed to atmosphere and without being ventilated till the SpO2 dropped to 92%.
The primary outcome compared between the groups was the safe apnea period
(time from loss of consciousness to fall of SpO2 to 92%).
Result
The duration of safe apnea period was longer (p < 0.05) in Group H patients (405.9
± 106.69 s) as compared to the Group C (296.9 ± 99.01s) and Group S (319.65 ±
71.54s). Although the duration of safe apnea period was longer in the Group S as
compared to Group C the difference was not statistically significant.
Conclusion
Preoxygenation in 25° head-up position with 5 cmH2O continuous positive airway
pressure significantly prolongs safe apnea period in non-obese adults compared to
supine position, with or without 5 cmH2O continuous positive airway pressure .
KEY WORDS
Apnea, CPAP, Preoxygenation
Description
Dhakal Y, Bhattarai B, Khatiwada S, Subedi A
Department of Anaesthesiology and Critical Care,
BP Koirala Institute of Health Sciences,
Dharan, Nepal.
Keywords
Apnea, CPAP, Preoxygenation