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Conscious Sedation

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During conscious sedation, there is minimal decrease in awakening level but patient breathes and responds to commands normally. During deep sedation, patient may not respond appropriately and his/her heart and lung function may be compromised.

•  Sedation for endoscopy is not used or expected in many countries. Some people feel that sedation is not absolutely necessary for endoscopy. In US, sedation for endoscopy is the standard of care.

• The goal of sedation should be to overcome anxiety and get cooperation from the patient. Patient should not remember any unpleasantness of the procedure. It can sometimes progress to anesthesia when verbal and eye contact are lost. Sometimes, deep sedation is the only thing that works!

• A variety of drugs are used for conscious sedation. Benzodiazepines as a class are used the most, followed by opiates, and general anesthesia. Among benzodiazepines, midazolam (Versed) is used more commonly than diazepam (Valium).

• Opiates (morphine like drugs) are good for both pain relief and sedation. Meperidine (Demerol) is the most frequently used drug in this class. The dose of these drugs that may slow or stop breathing may not be enough to cause the patient to fall asleep. Fentanyl is another morphine like narcotic that is occasionally used.

   

  Droperidol may be used when patients have paradoxical reaction to standard sedatives or as an adjunct. Haloperidol is similar to droperidol and is very effective in agitated patients. Propofol and self administered nitrous oxide are used by some physicians for sedation.   Combinations of opiates and benzodiazepines are widely used by endoscopists in the United States. The combination effect is much greater than the additive effect of these individual drugs. Thus there is increased chance of complications. Whether combining these drugs helps patient comfort or tolerance is unclear.

• Occasionally, even a combination of opiates and benzodiazepines in high doses may be ineffective in achieving the desired level of sedation. In such patients, the addition of antihistamines like diphenhydramine (benedryl) or phenergan may be helpful. Unusual combinations used include a mixture of Propofol, Ketamine, and lidocaine as an intravenous drip.

• Endoscopy should not be generally performed in agitated/uncooperative patients. On occasion, the endoscopy is absolutely necessary because of patient�s condition. Higher dose of sedatives may be required. Halodol is helpful adjunct. Skeletal muscle relaxants with ventilatory support or general anesthesia are occasionally employed.

• PREGNANT AND NURSING WOMEN: FDA categorizes include Category A (safest) though category D. Category X is the least safe and the risks are far greater than any benefit. Midazolam (Versed) is part Pregnancy category D whereas of diazepam (valium) should not be used at all. Meperidine, Fentanyl, Haloperidol and Droperidol all are included in FDA category C while Propofol is falls under category B.

• We should avoid Midazolam, Propofol, Fentanyl and Haloperidol in nursing mothers since they are excreted in mothers milk.

• It is believed that most serious events due to sedatives occur because of opiates. However, because of effective opiate blocker (naloxone), deaths are relatively rare. Thus in one study with seven deaths due to sedation, only one was due to opiates and six were due to benzodiazepines.

•  Various degrees of breathing problems may occur. Even extreme drop in oxygenation may not be detected clinically even in a well lit room. The explanation may lie in the mechanism of drugs. Opiates decrease the rate of breathing while benzodiazepines may increase it, thus offsetting each others effects on breathing rate. Thus a normal rate of breathing occurs which may however be shallow enough to cause significant drop in oxygenation. Its duration may extend well beyond the procedure.

• Death may occur related to endoscopy/sedation. Daneshmend and colleagues reported one death for every 7500 to 11,000 endoscopies. In the study by Arrowsmith et al., the death rate was 3 for every ten thousand endoscopies. From March 1986 to March 1990, there were 131 reports of serious complications of heart/lung (n=21,000) including 73 deaths related to midazolam.

• Venous complications are more frequent with diazepam than with midazolam.

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