Opiates. Additional analgesics are sometimes used to assist colonoscopy; the most common is a combination of benzodi-azepine and opiate (e.g., Dolantin). Dolantin (0.6-1 mg/kg) is administered intravenously. If combining substances one must be aware that the sedative effect of a benzodiazepine can be exponentially increased when used in combination with opiates, increasing the risk of respiratory depression. Flumazenil (Anexate) and Naloxon (Narcanti) are antagonists for benzodi-azepines and opiates.
Propofol. Another option is the use of propofol, which rapidly induces hypnosis and has a short half-life of 2-5 minutes. However, propofol has a very narrow therapeutic index; in other words, a small change in dosage can produce either a sedative or a narcotic effect. A notable side effect is the possibility of a pronounced drop in blood pressure; patient blood pressure must therefore be monitored closely. No antagonist is available for this drug and various professional organizations strongly recommend that propofol only be used when an anesthetist is immediately available (4, 9). However, results from a study in which nurses administered propofol during colonoscopy under supervision of the endoscopist (a nonanesthesiologist with training in emergency medicine) did not report any complications (8). In our opinion, propofol should only be used when a trained physician, experienced in emergency medicine, is present alongside the examiner to monitor the patient's condition.
Cardiopulmonary complications. In 0.1-0.5% of patients pre-medication causes serious cardiopulmonary complications. Thus, the adequate administration of medication and monitoring of the patient during and after examination are of the utmost importance.
■ Sedation and Analgesics
Colonoscopy can theoretically be performed without sedation, and there are no fixed rules for premedication. Nonetheless, premedication improves examination conditions for both patient and physician. This has been confirmed by results from a study by Terruzzi et al. comparing routine premedication prior to colonoscopy to "on-demand" sedation during the examination. Among patients who began the procedure without sedation, 66 % requested an analgesic during the examination and a larger number of them also refused to undergo another colonoscopy in the future (22% vs. 10% in the comparison group) (10).
Benzodiazepines. The vast majority of patients visiting our en-doscopic unit receive routine sedation prior to colonoscopy. "Conscious sedation" and, if possible anesthesia-induced amnesia, are desirable. Sedation is generally administered intravenously, using a benzodiazepine (Midazolam, Diazepam, Di-azemuls); Midazolam (Dormicum; 0.07-0.1 mg/kg i. v.) has the advantages of a pronounced amnestic effect and a short half-life of 1.5-3 hours.
■ Other Medications/Endocarditis Prophylaxis
Spasmolytics. In addition to analgesics, antispasmodics should be available during colonoscopy to inhibit intestinal peristalsis (e.g., Butylscopolamine [Buscopan]; or Glucagon if there are contraindications).
Prevention of Endocarditis. If the patient has preexisting cardiac disease, the prevention of endocarditis and the risk of bacteremia must be considered prior to examination. The risk of bacteremia is ca. 4% for colonoscopy and ca. 2% for sigmoidos-copy; polypectomies do not significantly increase the risk for bacteremia. However, given the high risk of endocarditis among patients with heart valve replacement or a medical history of endocarditis, an antibiotic prophylaxis must always be used. For low-risk or moderate-risk patients (e.g., hereditary or acquired heart valve disease without previous endocarditis, mitral valve prolapse with mitral insufficiency), antibiotics are not strictly required for ileocolonoscopy (7). Currently, there are no standard recommendations regarding medication; however, for endoscopy of the lower gastrointestinal tract Enterococcus faecalis,
Safety of the Patient and Monitoring in particular, should be considered a potential source of infection. In our clinic we administer ampicillin and gentamycin for patients with especially high risk before the examination begins and ampicillin again six hours after examination (orally for outpatient procedures, if appropriate). If the patient has a penicillin allergy, we use vancomycin combined with gentamycin (Tab. 4.1). Our procedures are based on the recommendations of the American Heart Association (AHA) (2).
Allergies and Contraindications. The patient must be carefully interviewed prior to examination regarding allergies or other contraindications related to any medications. Penicillin allergy is a common example of information required for using an endocarditis prophylaxis. Possible contraindications must also be ascertained if Buscopan is to be used, and the patient should be asked specifically about these. If the patient reports any contraindications or if they are indicated (e.g., glaucoma, urinary retention, tachyarrhythmia), it cannot be used. It is also advisable to inquire about possible pregnancy prior to colonoscopy.
Table 4.1 Endocarditis prophylaxis based on recommendations of the American Heart Association (2)
High risk for endocarditis:
► mechanical and bioprosthetic heart valves
► previous bacterial endocarditis
► cyanotic congenital heart disease
Antibiotic prophylaxis ampicillin 2 g i. v. and gentamycin 1.5 mg/kg i. v. (maximum 120 mg) before colonoscopy; ampicillin 1 g i.v. six hours after colonoscopy (alternative: amoxicillin 1 g orally six hours after colonoscopy)
in case of penicillin allergy: vancomycin 1 g i. v. (over 1-2 hours) and gentamycin 1.5 mg/kg i. v. (max. 120 mg) by start of colo-noscopy
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