Clinical practice guidelines: to what end?

The move to develop clinical practice guidelines in Australia is gaining momentum as part of a national approach to improving the quality of clinical practice. The National Health and Medical Research Council has published a "guidelines for guidelines". While it has also produced guidelines for nine specific clinical topics, it is now passing this role to professional organisations, such as clinical colleges and learned societies, and reverting to an overseeing, facilitating and credentialling role.

Control of defecation in patients with spinal injuries by stimulation of sacral anterior nerve roots.

OBJECTIVE: To observe the effects of stimulation of the sacral anterior roots on anorectal and low colonic pressures and to programme implanted stimulators to produce defecation. DESIGN: Prospective study of 12 consecutive patients. SETTING: Spinal injuries unit and university gastrointestinal physiology department. PATIENTS: 12 Patients with complete supraconal spinal cord lesions. Their injuries had been sustained at least two years before the study. INTERVENTIONS: A Brindley-Finetech intradural sacral anterior root stimulator was implanted in all patients. Three months postoperatively the stimulator settings were adjusted after measurement of simultaneous anorectal and low colonic pressures. MAIN OUTCOME MEASURES: Full defecation. RESULTS: Six patients achieved complete rectal evacuation of faeces using the implant and subsequently did not require manual help for defecation. For all but one of the patients the total time taken to complete defecation was reduced, and all were free from constipation, the most prevalent gastrointestinal symptom in patients with spinal injuries. CONCLUSIONS: Sacral anterior root stimulators can be programmed to achieve complete unassisted defecation and can considerably improve the quality of life of patients with spinal injuries.

Placental transfer of omeprazole in maternal and fetal sheep.

The placental transfer of omeprazole was studied over a 4-fold dose range in 7 nonanesthetized near-term pregnant sheep. There was a 5 to 1 maternal to fetal transplacental gradient of steady-state total omeprazole concentrations after both low dose (maternal plasma 556 +/- 361 ng/ml, fetal plasma 101 +/- 57 ng/ml) and high dose (maternal plasma 2,660 +/- 1,130 ng/ml, fetal plasma 563 +/- 182 ng/ml). Although this was in part due to differences in plasma protein binding between mother (unbound fraction 6.6 +/- 5.5%) and fetus (unbound fraction 11.9 +/- 2.4%), a 2 to 1 maternal to fetal gradient of steady-state unbound omeprazole concentration was still present (144 +/- 73 ng/ml vs. 64 +/- 32 ng/ml). Fetal omeprazole total plasma concentrations correlated strongly with maternal total drug concentrations (r = 0.84, p less than 0.025) and with the inverse of maternal omeprazole total systemic clearance (r = 0.77, p less than 0.05), indicating that maternal drug disposition was a major determinant of fetal omeprazole plasma concentrations. Urinary clearance of omeprazole was low in both mother (0.137 +/- 0.046 ml/min) and fetus (0.067 +/- 0.039 ml/min). This study demonstrates that the fetus is exposed to about one half of the unbound omeprazole concentration in maternal plasma and suggests that the extent of fetal exposure is largely dictated by maternal drug distribution and elimination characteristics.

High dose of antacid (Mylanta II) reduces bioavailability of ranitidine.

To investigate the effect of antacid on the bioavailability and disposition of ranitidine six healthy volunteers were studied on two occasions one week apart. In the first study the received ranitidine 150 mg with 60 ml water, and in the second study they received ranitidine 150 mg plus 30 ml of an aluminium/magnesium hydroxide mixture (Mylanta II) and 30 ml water. Giving antacid reduced both the maximum plasma ranitidine concentration and the area under the curve by one-third; elimination of the drug was not changed. Thus giving a high dose of antacid significantly diminished the bioavailability of ranitidine.

Consequences of ileal dysfunction: an approach to management.

Fourteen patients with ileal dysfunction due to resection or bypass were encountered over an 18-month period. Symptoms had been present for a mean period of 1.8 years. Diarrhoea was a universal symptom, and varied from mild to incapacitating. Weight loss, due in part to malabsorption and in part to the patients' fear of eating, occurred in 10 of 14 patients. The chief metabolic abnormalities were steatorrhoea and hypokalaemia. Vitamin B12 deficiency, folate deficiency, anaemia, hypoalbuminaemia, hypocalcaemia, hypomagnesaemia, hyperoxaluria, and an abnormal prothrombin ratio were less frequently seen. Treatment with cholestyramine and/or long-chain fat restriction effectively reduced diarrhoea in every case, and this was supplemented by replacement of specific deficiencies. There was little added benefit from non-specific antidiarrhoeal agents. It was found that the major symptoms of ileal dysfunction are readily treated, but that attention should also be given to a number of nutritional deficiencies.

The recognition and treatment of the irritable bowel syndrome.

The irritable bowel syndrome (IBS) is characterized by abdominal pain and/or altered bowel habit in the absence of detectable organic bowel disease. By convention, people with simple constipation are not usually included in this group of patients. IBS is a symptom-complex with many synonyms such as irritable colon, functional bowel disorder, nervous diarrhoea or spastic colon.

Glucagon and the colon.

The effect of glucagon on human colonic myoelectrical activity is described. By means of intraluminal, serosal, and surface electrodes, recordings from all areas of the large bowel have been obtained. Glucagon inhibited both electrical and pressure rhythms in all subjects tested. Evidence is produced to suggest a direct action on colonic smooth muscle. A controlled trial using glucagon during routine barium enema examinations suggests that it may prove to be useful for hypotonic examinations of the colon where painful spasm is present.