Parenteral nutrition.

Over the last 50 years, parenteral nutrition has been recognised as an invaluable and potentially lifesaving tool in the physician's arsenal in the management of patients with intestinal failure or inaccessibility; however, it may also be associated with a number of potentially life-threatening complications. A recent NCEPOD report (2010) identified a number of inadequacies in the overall provision and management of parenteral nutrition and recommendations were made with the aim of improving clinical practice in the future. This paper focuses on the practical aspects relating to parenteral nutrition for adults, including important concepts, such as patient selection, as well as general management. We also explore the various pitfalls and potential complications and how these may be minimised.

Systematic review: does gastro-oesophageal reflux disease progress?

BACKGROUND: Gastro-oesophageal reflux disease affects approximately 20% of western populations. Barrett's oesophagus, associated with severe gastro-oesophageal reflux disease, is premalignant and regular endoscopic surveillance is generally performed. In contrast, mild gastro-oesophageal reflux disease is thought not to progress and is not generally subjected to endoscopic follow-up. Aim To investigate whether gastro-oesophageal reflux disease progresses endoscopically. METHODS: Systematic review of the literature. RESULTS: Well-designed prospective studies are few, diagnostic criteria were not always standardized, management strategies varied and various sources of bias could not be excluded. Whilst most patients do not progress to more severe forms of gastro-oesophageal reflux disease, and some cases actually regress, progression is seen in a small proportion of patients. Annual progression rates for non-erosive gastro-oesophageal reflux disease developing erosive oesophagitis ranged from 0% to 30%. About 1-22% of patients with mild erosive oesophagitis developed more severe inflammation annually, while 1-13% of patients with erosive oesophagitis developed Barrett's oesophagus each year. CONCLUSION: Although most patients with gastro-oesophageal reflux disease do not progress, and some actually regress, progression does occur in a minority. Better data are required to determine whether patients with mild gastro-oesophageal reflux disease would benefit from increased surveillance with the aim of detecting more advanced disease.

The role of the hiatus hernia in gastro-oesophageal reflux disease.

A sliding hiatus hernia disrupts both the anatomy and physiology of the normal antireflux mechanism. It reduces lower oesophageal sphincter length and pressure, and impairs the augmenting effects of the diaphragmatic crus. It is associated with decreased oesophageal peristalsis, increases the cross-sectional area of the oesophago-gastric junction, and acts as a reservoir allowing reflux from the hernia sac into the oesophagus during swallowing. The overall effect is that of increased oesophageal acid exposure. The presence of a hiatus hernia is associated with symptoms of gastro-oesophageal reflux, increased prevalence and severity of reflux oesophagitis, as well as Barrett's oesophagus and oesophageal adenocarcinoma. The efficacy of treatment with proton pump inhibitors is reduced. Our view on the significance of the sliding hiatus hernia in gastro-oesophageal reflux disease has changed enormously in recent decades. It was initially thought that a hiatus hernia had to be present for reflux oesophagitis to occur. Subsequently, the hiatus hernia was considered an incidental finding of little consequence. We now appreciate that the hiatus hernia has major patho-physiological effects favouring gastro-oesophageal reflux and hence contributing to oesophageal mucosal injury, particularly in patients with severe gastro-oesophageal reflux disease.

Diverticular disease of the colon: ethnic differences in frequency.

BACKGROUND: Colonic diverticular disease is more common in Western populations than in developing countries. AIM: To determine whether the frequency of colonic diverticular disease is different in British patients of Indian-subcontinent Asian origin compared with other ethnic groups. METHODS: All colonoscopies performed over a 3-year period in a London hospital were studied. Patients of Indian-subcontinent Asian origin were identified by name. RESULTS: Five of 134 Indian-subcontinent Asian males (4%) had colonic diverticular disease, compared with 278 of 1268 patients of other ethnic groups (22%; P < 0.001). Five of 91 Indian-subcontinent Asian females (6%) had colonic diverticular disease, compared with 333 of 1486 patients of other ethnic groups (23%; P < 0.001). Although patients of Indian-subcontinent Asian origin (54.8 +/- 15.8 years) were younger than those of other ethnic groups (60.3 +/- 17.8 years; P < 0.0001), the ethnic difference in the frequency of diverticular disease persisted even when age was taken into account. CONCLUSION: There is a lower frequency of colonic diverticular disease in Indian-subcontinent Asians presenting for colonoscopy, compared with other ethnic groups. This cannot be explained by sex or age differences. Our findings require confirmation, but may provide opportunities for research into the aetiology of colonic diverticular disease.

Effect of octreotide on small intestinal motility in HIV-infected patients with chronic refractory diarrhea.

Octreotide has been used to treat HIV-associated diarrhea. We aimed to assess the effect of octreotide on small intestinal motility in a group of HIV infected individuals with chronic diarrhea. Small intestinal motility was measured continuously for 48 hr by ambulatory strain gauge manometry in 12 HIV seropositive subjects with chronic diarrhea. During the second 24-hr period, intravenous octreotide was administered (100 microg every 8 hr). Postprandial and nocturnal fasting motility data were compared before and during administration of octreotide. Octreotide was associated with increased numbers of migrating motor complexes (MMCs) (7.25 vs 4.92, P = 0.03), and a relative decrease in the duration of phase II (22% vs 49.8, P = 0.03) during nocturnal fasting activity. Postprandial activity was absent in half of the subjects and the duration significantly reduced in the remainder. In conclusion, octreotide has a significant effect on small intestinal motility in HIV-infected individuals with diarrhea, which may influence intestinal transit.

Delayed gastric emptying in human immunodeficiency virus infection: correlation with symptoms, autonomic function, and intestinal motility.

Gastric emptying may be delayed in HIV infection. We aimed to characterize the pattern of gastric emptying in HIV seropositive subjects and correlate the findings with symptoms, as well as to identify possible etiological factors. Solid gastric emptying was measured using scintigraphy in 54 HIV seropositive subjects and 12 HIV seronegative controls. Gastrointestinal symptoms were evaluated using a standardized numerical score, and autonomic function was assessed using spectral analysis of heart rate variability. Fasting and postprandial duodenojejunal activity was recorded using strain gauge manometry catheters. Gastric emptying rate, but not lag phase, was significantly delayed in HIV-infected subjects, particularly those with enteric infections and more advanced disease. Delayed gastric emptying did not correlate with symptoms, autonomic dysfunction, or small intestinal motility. In conclusion, abnormalities found in autonomic function and gastric emptying in HIV infection are multifactorial in nature. The contribution of upper gastrointestinal motor dysfunction to gastric symptoms in such individuals is unclear.

Cardiac autonomic dysfunction in AIDS is not secondary to heart failure.

OBJECTIVE: Heart rate variability (HRV) is a marker of cardiovascular autonomic tone, and is also known to be reduced in association with cardiac dysfunction. Abnormal autonomic function tests are common in HIV infected individuals, but the contribution of heart disease to such findings is not known. Spectral analysis of heart rate variability is a sensitive technique for measurement of cardiovascular autonomic function, which also allows differential assessment of parasympathetic and sympathetic components. The aim of this study was to characterise the nature of autonomic dysfunction in patients with AIDS and to compare our findings with those seen in HIV seronegative patients with established heart disease. METHODS: HRV was measured prospectively by spectral analysis in 10 subjects with dilated cardiomyopathy (age 45.7+/-6.9 years), 10 subjects with AIDS and no clinical evidence of heart disease (age 37.9+/-5.4 years), and 10 healthy HIV seronegative controls (age 41.7+/-13.9 years). RESULTS: All components of HRV were reduced in subjects with cardiomyopathy (P<0.005), and markedly so in subjects with AIDS (P<0. 0001) compared with controls. CONCLUSIONS: HIV infection may be associated with severe global autonomic dysfunction, which is not related to heart disease.

Small intestinal transit, absorption, and permeability in patients with AIDS with and without diarrhoea.

BACKGROUND: Diarrhoea in AIDS is associated with anorexia and weight loss. The importance of gastrointestinal transit in such symptoms has not been addressed. AIMS: To assess jejunal to caecal transit times in subjects with AIDS related diarrhoea and weight loss and correlate these with measures of absorptive capacity and intestinal permeability. METHODS: Jejunal to caecal transit times were assessed in 20 seronegative controls and 60 HIV seropositive subjects from serum analysis of 3-O-methyl-D-glucose and sulphapyridine after ingestion of the monosaccharide and sulphasalazine in aqueous solution. The method also allows an estimation of gastric emptying times for liquids. Intestinal absorptive capacity and permeability were assessed by a combined test using 3-O-methyl-D-glucose, D-xylose, L-rhamnose, and lactulose. RESULTS: Gastric emptying was significantly delayed in all groups of patients with AIDS. Mean jejunal to caecal transit times were not significantly different between controls (246 (62) minutes) and patients without diarrhoea (AIDS, well: 278 (103) minutes; AIDS, wasting: 236 (68) minutes), cytomegalovirus colitis (289 (83) minutes), pathogen negative diarrhoea (192 (100) minutes), or microsporidiosis (190 (113) minutes), although 30% of patients had values below the control range. Patients with cryptosporidiosis differed significantly from controls (135 (35) minutes, p<0.0001), seven of 10 having rapid transit times. Absorptive capacity was reduced and intestinal permeability significantly increased in AIDS, but did not correlate significantly with transit times. CONCLUSION: Small bowel transit is accelerated in many patients with AIDS, particularily in protozoal diarrhoea, but is not the sole explanation for malabsorption of monosaccharides.

Detection of herpesvirus DNA by nested polymerase chain reaction in cerebrospinal fluid of human immunodeficiency virus-infected persons with neurologic disease: a prospective evaluation.

A nested polymerase chain reaction-based method was used prospectively to detect herpesvirus DNA in cerebrospinal fluid (CSF) from 111 patients with AIDS, 39 of whom had a suspected diagnosis of cytomegalovirus (CMV)-associated neurologic disease (patients with encephalopathy, polyradiculopathy, or peripheral neuropathy) and 72 who had alternative diagnoses. CSF from 24 (62%) of the patients with suspected CMV-associated disease had detectable CMV DNA compared with only 8 (11%) of the patients with other diagnoses. Varicella-zoster virus DNA was detected in CSF from 3 patients (2 with myelitis and 1 with encephalitis), all of whom had recent cutaneous zoster. No CSF specimen contained detectable herpes simplex virus type 1 DNA, and none of the patients with myelitis had detectable herpes simplex virus type 2 DNA in CSF. This study demonstrates a significant association between detectable CMV DNA in CSF and suspected CMV-associated neurologic disease in patients with AIDS.

Cold-induced increases in erythrocyte count, plasma cholesterol and plasma fibrinogen of elderly people without a comparable rise in protein C or factor X.

1. Six elderly (66-71 years) and six young (20-23 years) subjects (half of each group women) were cooled for 2 h in moving air at 18 degrees C to investigate possible causes of increased mortality from arterial thrombosis among elderly people in cold weather. Compared with thermoneutral control experiments, skin temperature (trunk) fell from 35.5 to 29.5 degrees C, with little change in core temperature. 2. Erythrocyte count rose in the cold from 4.29 to 4.69 x 10(12)/l, without a change in mean corpuscular volume, indicating a 14% or 438 ml decline in plasma volume; increased excretion of water, Na+ and K+ accounted for loss of only 179 ml of extracellular water. 3. Plasma cholesterol and fibrinogen concentrations rose in the elderly subjects from 4.90 mmol/l and 2.97 g/l (control) to 5.45 mmol/l and 3.39 g/l in the cold, and in the young subjects from 3.33 mmol/l and 1.84 g/l (control) to 3.77 mmol/l and 2.07 g/l in the cold. Increases were significant for the elderly subjects, the young subjects and the group as a whole, except for cholesterol in the young subjects, and all were close to those expected from the fall in plasma volume. 4. Plasma levels of Protein C and factor X did not increase significantly in the cold in the elderly subjects, young subjects, or the group as a whole. 5. The results suggest that loss of plasma fluid in the cold concentrates major risk factors for arterial thrombosis, while small molecules, including protective Protein C, redistribute to interstitial fluid.