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

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 pre-oxygenation with 4 litres/minute for five minutes before sedation was used, followed by continuous oxygen administration, arterial oxygen saturation did not fall 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.