Before the Examination

4	Before the Examination A. Probst

Informing the Patient

The decision if colonoscopy is the best diagnostic or therapeutic approach should be made based on present indications (see also Chapter 1). If the indication supports the need for colonoscopy, the patient must be informed prior to examination about the necessity, procedure, and possible complications of the examination and he must sign a consent form.

Serious complications are rare and the vast majority are due to cardiopulmonary complications. Risk varies greatly from one individual to the next, depending on cardiopulmonary disease status and the use of an analgesic. In addition to more general risks, there are also potential complications specifically related to colonoscopy (foremost bleeding and perforation; see also Chapter 1). In any discussion preceding colonoscopy, the patient must also be informed of the possibility of polypectomy, which entails increased risk.

For outpatient examinations, the patient must be cautioned against performing any activities that could cause harm to him or others for a period of 24 hours following sedation (e.g., driving, operating heavy or complex machinery, signing important documents such as contracts). Alternative examination and therapeutic options should also be mentioned. Standardized written consent forms may make discussion and documentation easier, but they cannot replace an informative discussion. The patient must be given sufficient time between discussion and the actual examination to consider his decision; according to German law, the examination can be performed no sooner than one day after the discussion between patient and physician (7).

Sedation and Medication

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, Diazemuls); 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.

Opiates. Additional analgesics are sometimes used to assist colonoscopy; the most common is a combination of benzodiazepine 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 benzodiazepines 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 premedication causes serious cardiopulmonary complications. Thus, the adequate administration of medication and monitoring of the patient during and after examination are of the utmost importance.

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 en-doscopy of the lower gastrointestinal tract Enterococcus faecalis,

Only gold members can continue reading. Log In or Register to continue