Preparation, premedication, and surveillance.

The endoscopic literature published during the past year has once again confirmed that there is significant variation from country to country regarding whether or not patients wish to receive conscious sedation during endoscopy (and particularly colonoscopy) - and there may even be variation from one endoscopic unit to another within the same country. Particular attention has been given to attempts to identify "ideal" candidates for conscious sedation, and to the importance of providing patients with information before the procedure. It has been shown that patients who receive detailed information about a medical procedure beforehand are able to benefit from this. The role of benzodiazepines, particularly midazolam, was investigated in studies emphasizing that the dosage should be kept to the minimum that is compatible with patient comfort and successful performance of the procedure. There have been few publications comparing propofol with midazolam. As expected, in view of the known pharmacological properties of the two drugs, the quality of sedation was better and the recovery time was shorter in patients who were treated with propofol. However, important questions are still open regarding the narrow therapeutic range of propofol and the methods by which it is administered (by endoscopists or by anesthesiologists). An important aspect of sedation procedures is the prevention of hypoxia and cardiopulmonary complications. Recent endoscopic reports have added little further information concerning the well-known risk of oxygen desaturation during conscious sedation. Performing endoscopy in unsedated patients reduces, but does not eliminate, the risk of hypoxia. Among the various risk factors, it has been found that chronic respiratory failure and coronary heart disease are factors predictive of severe desaturation and relevant electrocardiographic changes. The use of electronic monitoring techniques with pulse oximetry is recommended as a standard procedure during digestive endoscopy; however, it has been observed that when supplemental oxygen is administered, pulse oximetry no longer reflects normal ventilatory function and does not detect episodes of severe CO2 retention. Transcutaneous measurement of PCO2 therefore seems more reliable as a means of assessing hypoventilation. Several papers have proposed "ideal formulas" for bowel preparation for endoscopic procedures. Various regimens have been proposed as alternatives to polyethylene glycol electrolyte lavage solution (PEG-ELS) and sodium phosphate compounds, with different results. On the whole, there is still little information regarding the best and most cost-effective method of bowel cleansing for colonoscopy and flexible sigmoidoscopy.