On the mechanical behavior of the human biliary system.

This paper reviews the progress made in understanding the mechanical behaviour of the biliary system. Gallstones and diseases of the biliary tract affect more than 10% of the adult population. The complications of gallstones, i.e. acute pancreatitis and obstructive jandice, can be lethal, and patients with acalculous gallbladder pain often pose diagnostic difficulties and undergo repeated ultrasound scans and oral cholecystograms. Moreover, surgery to remove the gallbladder in these patients, in an attempt to relieve the symptoms, gives variable results. Extensive research has been carried out to understand the physiological and pathological functions of the biliary system, but the mechanism of the pathogenesis of gallstones and pain production still remain poorly understood. It is believed that the mechanical factors play an essential role in the mechanisms of the gallstone formation and biliary diseases. However, despite the extensive literature in clinical studies, only limited work has been carried out to study the biliary system from the mechanical point of view. In this paper, we discuss the state of art knowledge of the fluid dynamics of bile flow in the biliary tract, the solid mechanics of the gallbladder and bile ducts, recent mathematical and numerical modelling of the system, and finally the future challenges in the area.

Effectiveness of an upper-gastrointestinal haemorrhage unit: a prospective analysis of 900 consecutive cases using the Rockall score as a method of risk standardisation.

OBJECTIVES: To assess the effectiveness of a centralised upper-gastrointestinal haemorrhage (UGIH) unit. METHODS: The UK Audit of acute UGIH resulted in the formulation of a simple numerical scoring system. The Rockall score categorises patients by risk factors for death and allows case-mix comparisons. A total of 900 consecutive patients admitted to a UGIH unit between October 1995 and July 1998 were analysed prospectively. Patients were given an initial Rockall score and, if endoscopy was performed, a complete score. This method of risk stratification allowed the proportion of deaths (in our study) to be compared with the National Audit using risk standardised mortality ratios. RESULTS: The distribution of both initial and final Rockall scores was significantly higher in our study than in the National Audit. A total of 73 (8.1%) patients died, compared with the National Audit mortality of 14%. Risk-standardised mortality ratios using both initial and complete Rockall scores were significantly lower in our study when compared with those in the National Audit. CONCLUSION: A specialised UGIH unit is associated with a lower proportion of deaths from UGIH, despite comprising a greater number of high-risk patients than the National Audit. This lower mortality therefore cannot be attributed to a more favourable case mix and demonstrates that further improvements in mortality for UGIH can be made.

Simplified acute physiology score II: a valid role in the assessment of patients with medically refractory upper gastrointestinal bleeding?

BACKGROUND AND AIM: Medically refractory upper gastrointestinal hemorrhage (UGIH) is a complex clinical problem. Selection of patients suitable for surgery is difficult and often involves subjective clinical judgment. The simplified acute physiology score (SAPS) II is a validated predictor of mortality in the intensive care setting. Our aim was to assess the SAPS II score in patients with medically refractory UGIH who were referred for a surgical opinion. Patients were subsequently classed as 'accepted' or 'declined' for surgery and SAPS II scores were compared between these two groups. METHODS: From July 1996 to July 1999, patients referred for surgical intervention with UGIH were included (varices excluded). The SAPS II was calculated at the time of surgical referral. This was converted into a mortality probability using multiple regression analysis. Clinical outcome was defined as either survival to discharge or death while an inpatient. RESULTS: Ninety-nine patients were referred for surgical review. Sixty-five patients were accepted for surgery and 34 were declined. The mean SAPS II score for those who were accepted was 31.7 (mortality probability 0.16, actual mortality 15.4%, 10/65) and 30.2 (mortality probability 0.15, actual mortality 29.4%, 10/34) for those who were declined. CONCLUSION: The SAPS II scores were no different between the two groups. Observed mortality was consistent with mortality predicted in the operated group but twice that predicted in those where surgical intervention was declined. This suggests that clinical selection criteria for patients undergoing surgery for UGIH are inconsistent.

Does the addition of a prokinetic to proton pump inhibitor therapy help reduce duodenogastro-oesophageal reflux in patients with Barrett's oesophagus?

OBJECTIVE: The metaplastic change of Barrett's oesophagus is linked to both acid and duodenal reflux together with impaired motility. Proton pump inhibitors (PPI) reduce acid reflux, but no treatment is available that reduces duodenogastro-oesophageal reflux (DGOR). The aim of this study was to investigate whether adding a prokinetic to PPI treatment could improve oesophageal motility and subsequently reduce reflux. METHODS: Two groups of patients with Barrett's oesophagus on PPI therapy (prokinetic, n = 12; placebo, n = 11) were investigated. At visit 1, ambulatory oesophageal manometry was performed, and peristaltic and simultaneous wave percentage and characteristics were measured. DGOR and pH measurements were also performed. After treatment with either the prokinetic cisapride or placebo, all investigations were repeated (visit 2). Analysis of covariance and Spearman's correlation coefficients of changes from visit 1 to visit 2 were used to compare data. RESULTS: There was no significant difference between the two groups with respect to DGOR, DGOR characteristics, or the percentage of peristalsis and simultaneous waves and their characteristics. There was no correlation between DGOR and motility changes. Although no significant differences existed between acid reflux in the two groups, five patients with high supine acid reflux showed a significant reduction after treatment with cisapride. CONCLUSIONS: Addition of cisapride to PPI treatment does not appear to improve oesophageal motility or reduce DGOR in patients with Barrett's oesophagus.