Oxygen saturation during endoscopic retrograde cholangiopancreatography: a comparison of two protocols of oxygen administration.

Abstract

Patients having endoscopic retrograde cholangiopancreatography (ERCP) are generally elderly and require sedation while in the prone position. These factors may be expected to aggravate any risk of arterial hypoxia. This study evaluated two protocols of oxygen administration, one with and one without pre-oxygenation. In 25 patients in whom preoxygenation with 4 litres/minute for five minutes before sedation was used, followed by continuous oxygen administration, arterial oxygen saturation did not fail below 90% at any stage during the procedure. By contrast, in 25 patients who were not pre-oxygenated oxygen saturation fell below 90% in nine (36%). As expected, hypoxia occurred most frequently during the early stages of sedation and endoscope insertion. Hypoxia did not occur in association with operations such as sphincterotomy, stone extraction or stent insertion. This study confirms that arterial hypoxia is a common event during ERCP and can be completely prevented by pre-oxygenation with four litres of oxygen given intranasally for five minutes before sedation.

Hypoxia during upper gastrointestinal endoscopy with and without sedation and the effect of pre‐oxygenation on oxygen saturation

“…Several studies have looked at the mode of delivery of supplementary oxygen for patients undergoing upper gastrointestinal endoscopy: oxygen adminstration via nasal catheters [7] or oxygenating mouthguards [8], the effect of different oxygen flow rates [9] on maintenance of normoxaemia, the effect of pre‐oxygenation versus only giving oxygen during endoscopy [10] and the effect of supplemental oxygen during the procedure itself [11]. However, no other study has attempted to compare the effect of varying the time of pre‐oxygenation, as conducted in our study.…”

“…Rigg et al . [10] and Reed et al . [6] both recommended oxygen supplementation at 4 l.min −1 intranasally, to be given at 5 min and 2 min, respectively, before the start of endoscopy.…”

“…Withholding sedation does not necessarily prevent desaturation and hypoxia in patients undergoing endoscopy, and although sedation increases the incidence of desaturation and hypoxia, this can be completely abolished by supplementary nasal oxygen at 4 l.min −1. Since our study has shown that pre‐oxygenation confers no additional benefit, we propose that the ‘pre‐oxygenation’ time recommended by other authors [6–10] should be omitted. This could be cost and time saving, especially in a busy endoscopy unit.…”

Anaesthesia for endoscopic retrograde cholangiopancreatography

“…Various studies have shown a higher rate of hypoxia in ERCPs performed without adequate pre‐oxygenation 49,50 . Hypoxia is more likely to occur within 15 min of commencement of ERCP.…”

“…The technique of continuous pre‐oxygenation with 100% oxygen for a few minutes has been found to be superior to the four vital capacity breath technique 52,53 . Rigg et al 50 found pre‐oxygenation with 4 l/min oxygen intranasally for duration of 5 min to be adequate. In their study, pre‐oxygenated patients maintained their saturations above 90%, even with sedation levels likely to cause desaturation.…”