SEDATION AND MONITORING IN GASTROINTESTINAL ENDOSCOPY

The use of sedation and monitoring in gastrointestinal endoscopy is still open for debate. In The Netherlands, generally, no systemic sedation is used for relatively simple procedures like diagnostic upper GI endoscopy and sigmoidoscopy. In most centres, for more time-consuming and burdensome endoscopies like colonoscopy, ERCP, sclerotherapy and therapeutic procedures, some form of sedation is applied. In a survey among a number of University Hospitals in The Netherlands it was shown that the sedatives mostly used are midazolam and diazepam. In more complex endoscopies these sedatives are often combined with narcotics like pethidine, morphine, fentanyl or thalamonal. Equipment to monitor the effect of these compounds on respiratory or cardiovascular function is not routinely available. However, there is a tendency towards the use of monitoring equipment and more specific to the use of pulse oximetry. Endpoints of conscious sedation are anxiolysis, amnesia and cooperation; it should not lead to ptosis, dysarthria and drowsiness. Features of drugs for conscious sedation should include these aforementioned points as well as a defined dose-effect relationship and a broad therapeutic window. Furthermore, they should be water soluble and give rapid recovery. Signs of oversedation are hypotension, bradycardia and respiratory depression. Competitive antagonists to the receptor, like flumazenil, can reverse overdosage of benzodiazepine sedatives. The sedative of choice at this moment is midazolam. When a benzodiazepine is combined with a narcotic, the narcotic should be given first and the dosage of the sedative adjusted. Monitoring the patient during conscious sedation is first of all a matter of clinical judgement, but in more time-consuming and difficult procedures the use of a monitor device is advised. Since hypoventilation with a low oxygen saturation is the most important side effect of sedation, a pulse oximeter is the most relevant equipment. In cardiovascular high-risk patients, monitoring the heart rhythm is indicated as well. In long-standing upper gastrointestinal therapeutic procedures the administration of supplemental oxygen can prevent many of the ventilation problems of sedation.