Monitoring during sedation for endoscopy

Comparison of colonoscopies performed under sedation with propofol or with midazolam or without sedation

BACKGROUND

Previous studies have shown that some patients are not able to tolerate colonoscopy without sedation because of low pain threshold, anxiety, colonic sensitivity and anatomical variations. Benzodiazepines are most commonly used, often in combination with pethidine. Our study compares sedation with propofol to midazolam and colonoscopy without sedation.

METHODS

In this study 147 patients were examined. The patients were divided into three groups: The first group included patients in whom propofol was used for sedation, the second group included patients sedated with midazolam, and the third group was comprised of patients who received no sedation. Oxygen saturation and heart rate were recorded continuously by pulse oxymetry. Arterial blood pressure (BP) was monitored at 3-min intervals.

RESULTS

A decrease in blood pressure and heart rate was documented in the first two groups (P < 0.001), whereas in group 3 we found an increase in both BP and heart rate (P < 0.001). Oxygen saturation dropped below 90 % in 11/102 patients sedated with propofol and in 9/23 sedated with midazolam. Two of 22 patients in whom no sedation was used were found to have oxygen saturation below 90 %. The recovery time was shorter (7 min) in group 1 (propofol) than in group 2 (midazolam), in which it was found to be 20 min.

CONCLUSIONS

Our results showed that propofol provided good sedation with excellent pain control, a short recovery time and no significant haemodynamic side effects.

Propofol for sedation during endoscopy: assessment of a computer-controlled infusion system

Propofol can be used to provide general anesthesia or sedation. Twenty patients scheduled for upper gastrointestinal endoscopy were sedated using a computer-controlled system and endoscopy was performed by the same operator. Oxygen saturation reduced significantly (p less than 0.001) during the procedure, and remained significantly lower than baseline values at the end of the procedure. Patient assessment of sedation and anxiety using linear analogue scales showed a significant increase in sedation (p less than 0.00001) and decrease in anxiety (p less than 0.003) compared with baseline values. There were variable positive (p less than 0.001) and negative (p less than 0.002) changes in blood pressure from baseline values. Overall conditions for endoscopy were good. Computer-controlled delivery of propofol provides satisfactory sedation and conditions for upper gastrointestinal endoscopy and merits further investigation.

Examination of cardiorespiratory changes during upper gastrointestinal endoscopy. Comparison of monitoring of arterial oxygen saturation, arterial pressure and the electrocardiogram

Critical events including hypoxaemia, arrhythmias and myocardial ischaemia may occur more frequently during endoscopic procedures than during anaesthesia. A study was undertaken to assess the cardiovascular changes and to evaluate suitable monitoring techniques to detect critical events during sedation and endoscopy. Twenty patients scheduled to undergo a prolonged endoscopic procedure which required deep sedation were studied. Continuous recordings of electrocardiogram, heart rate and arterial oxygen saturation were made and arterial pressure was recorded at one-minute intervals. The study commenced immediately before administration of sedatives, continued for the duration of the examination and for one hour following the examination. Oxygen saturation decreased in all patients during the examination to a mean of 82.9% (SD 11.9), and remained below baseline for the duration of the examination and into the recovery period. Statistically significant increases and reductions of systolic arterial pressure and rate-pressure product were found during the procedures compared with baseline values recorded before administration of sedatives. Sixteen of the 20 patients developed tachycardia during the examination. Ten patients developed ectopic foci which were supraventricular, ventricular or both in origin. Electrocardiogram changes resolved during the recovery period. Myocardial ischaemia was assessed by S-T segment depression and a significant correlation was found between S-T segment depression and hypoxaemia, although the magnitude of the S-T depression was small and may not have been detected clinically. No correlation was found between S-T segment depression and arterial pressure, heart rate or rate-pressure product.(ABSTRACT TRUNCATED AT 250 WORDS)

Falls in hemoglobin saturation during ERCP and upper gastrointestinal endoscopy

Fiberoptic endoscopy is practiced everyday in the field of gastroenterology and, for diagnostic purposes, carries a risk of complications and an estimated mortality of 1:5,000, which is multiplied several times during interventional procedures. Half of these complications have a cardiopulmonary origin which may be anticipated by the use of pulse oximetry to measure hemoglobin saturation (SaO2). We studied 132 patients undergoing diagnostic or procedural endoscopic retrograde cholangiopancreatography (ERCP) under sedation, and 51 undergoing esophagogastroduodenoscopy (EGD) without sedation. In the ERCP group, SaO2 fell from 95.7 +/- 2.4% (mean +/- standard deviation) to 88.9 +/- 6.4% (p less than 0.001) with a corresponding rise in pulse from 95 +/- 19 to 116 +/- 18/min (p less than 0.001) followed by recovery. The largest falls followed positioning of the endoscope (rather than following administration of the sedative or the procedure), particularly during introduction of the endoscope within 1 minute of administering diazemuls (diazepam). The EGD group also had a fall in SaO2 (97.3 +/- 1.9% to 93.9 +/- 3.3%, p less than 0.001), although the patients were younger and undergoing shorter examinations. Again, the largest falls occurred 1 minute after introduction of the endoscope. In subgroups of patients undergoing ERCP, analysis of respiratory patterns using spectral techniques and electrocardiogram during endoscopy (n = 25), or peripheral perfusion using transcutaneous oximetry and laser Doppler velocimetry (n = 12) was undertaken. No correlations were found in relation to changes in SaO2. The cause of the fall in SaO2 during endoscopy is multifactorial.(ABSTRACT TRUNCATED AT 250 WORDS)

Review article: premedication and intravenous sedation for upper gastrointestinal endoscopy

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.

Hypoxia and hypotension during endoscopy and colonoscopy

Sixty-three patients undergoing oesophagogastroduodenoscopy (OGD) (n = 24) or proctosigmoidocolonoscopy (PSC) (n = 39) had continuous monitoring of arterial oxygen saturation (SaO2), pulse and mean blood pressure (BP). The degree of patient distress, duration, dose of sedative and details of the endoscope and operator were recorded. Marked hypotensive (greater than 40% fall in BP) and hypoxic (greater than 8% fall in SaO2) changes occurred in 13% and 17% of the overall group, respectively. There were no significant differences in fall in BP, SaO2 or pulse between the OGD and PSC groups. The dose of sedative was significantly related to the fall in SaO2 (P less than 0.001) but not to the fall in BP. The falls in both SaO2 and BP were related to the duration of the procedure (P less than 0.001, P = 0.03, respectively). There were no correlations between the degree of hypoxia or hypotension and the patient's age or previous medical history. Hypotension and hypoxia occur in both colonoscopy and OGD and are neither predictable nor usually recognizable clinically. Pulse oximetric and BP monitoring throughout gastrointestinal endoscopy are recommended for maximal safety.