https://www.gastrojournal.org/article/0016-5085(95)90441-7/pdf

Conscious Sedation for Gastroscopy: Patient Tolerance and Cardiorespiratory Parameters

SUMMARY

Upper gastrointestinal endoscopy can be performed without intravenous sedation but the evidence suggests that, in the United Kingdom and United States, most patients and endoscopists prefer that some form of premedication is given. Intravenous diazepam or midazolam are used by the majority of endoscopists. In the UK, the ratio of diazepam to midazolam users is approximately 2:1, while in the USA more endoscopists are now using midazolam. Midazolam is approximately twice as potent as diazepam but, when allowance is made for this, there is probably little or no difference in the propensity of the two drugs to produce respiratory depression. The antegrade amnesic effect of midazolam is significantly superior to that of diazepam. A benzodiazepine/narcotic combination can achieve a smoother and more rapid induction with less gagging and choking, but the incidence of adverse outcomes—particularly respiratory depression—is increased significantly. Over 50% of the deaths that are associated with upper gastrointestinal endoscopy are due to cardiopulmonary problems. Hypoxia is very common if measured using non-invasive monitoring equipment, such as a pulse oximeter. Methods of preventing oxygen desaturation and thus, by inference, most cardiac arrhythmias associated with endoscopy are discussed, as is the role of flumazenil, the new benzodiazepine antagonist.

Review article: premedication and intravenous sedation for upper gastrointestinal endoscopy

https://www.giejournal.org/article/S0016-5107(97)70295-5/pdf

Sedation and analgesia for colonoscopy: patient tolerance, pain, and cardiorespiratory parameters

Respiratory physiology in upper abdominal surgery.

Background/Aims: Although prolonged hypoxemia (henceforth referred to as hypoxemia) is not uncommon during moderate sedation for endoscopy, there are only sparse data regarding its

Hypoxemia during moderate sedation for gastrointestinal endoscopy: causes and associations.

Hypoxemia during esophagogastroduodenoscopy (EGD), or panendoscopy has been generally attributed to sedation. We studied 49 patients ranging in age from 17 to 71 years with normal or nearly normal lung function undergoing EGD to determine the effects of sedation and the effects of the endoscope on arterial oxygen saturation (SaO2). All patients received intravenous diazepam and 41 also received meperidine. EGD was delayed 10.7 +/- 7.5 min after intravenous diazepam administration in the 42 group 1 patients. Seven patients underwent EGD within 2 min of receiving intravenous diazepam (group 2). Ventilation decreased after diazepam, recovered, then decreased immediately after endoscope insertion in the group 1 patients. Periods of hypopnea, up to 39 s long, were observed during EGD. The average decrease in SaO2 was 4.0% after diazepam (p less than 0.0001). SaO2 returned to the pre-EGD level, then decreased 2.4% during EGD (p less than 0.0005). Maximum SaO2 decrease occurred 27 +/- 6 s after insertion of the endoscope then rapidly recovered. There was a linear correlation between the duration of hypopnea and maximum SaO2 decrease (r = 0.84, p less than 0.001). All group 2 patients experienced a period of hypopnea (13.3 +/- 9.6 s) and SaO2 declined 9.0%. The SaO2 decline was significantly greater in the group 2 subjects (p less than 0.0001). Our results confirm previous findings that intravenous sedation causes hypoventilation and hypoxemia. Moreover, hypoventilation and further arterial oxygen desaturation are caused by either the mechanical effect of the endoscope or a reflex stimulated by it.

Stephen K. Field

Papers

Mechanisms of hypoxemia during panendoscopy.