Liver and intestinal lactate metabolism in patients with acute hepatic failure undergoing liver transplantation.

OBJECTIVE: To determine the relative contribution of the gastrointestinal tract and the liver in lactate metabolism in patients with acute liver failure (ALF) and the effect of liver transplantation on this. We hypothesized that the liver and gut are net producers of lactate in ALF and that this is reversed after liver transplantation. SETTING: A university-affiliated specialist liver transplant operating theater. SUBJECTS: Eleven patients with ALF undergoing liver transplantation. MEASUREMENTS AND INTERVENTIONS: After ethical approval, 11 patients with ALF listed for orthotopic hepatic transplantation were studied. Whole blood was analyzed for lactate concentration from radial artery (RA) catheter, portal vein (PV), and hepatic vein (HV) during the dissection phase and was repeated postreperfusion of the liver graft. Gradients across the gut and the liver were calculated to see if there was net production or consumption. RESULTS: HV lactate was significantly higher than arterial (p =.028) in patients with ALF before liver transplantation, suggesting splanchnic production of lactate. Total splanchnic lactate gradient (HV-RA) is positive in ALF. Both the gut (PV-RA) and the liver (HV-PV) were net producers of lactate. After liver transplantation, hepatic venous lactate falls below arterial levels but not significantly. The gradient across the gut (PV-RA) remained positive, but the transhepatic gradient (HV-PV) became significantly negative, showing consumption by the graft (p =.021). The magnitude of lactate consumption after transplantation correlated positively with portal venous lactate concentration (p =.029) and inversely with graft cold ischemic time (p =.007). CONCLUSION: The liver is a net producer of lactate in patients with ALF and an elevated whole blood lactate. After liver transplantation, the graft becomes a consumer of lactate as shown by the negative lactate gradient. The degree of consumption is dependent on portal venous lactate concentration and cold ischemic time.

Metoclopramide improves gastric motility in critically ill patients.

OBJECTIVE: To assess the effect of metoclopramide on gastric motility in critically ill patients. DESIGN: Prospective, controlled, single-blind cross-over trial. SETTING: A 10-bed general intensive care unit. PATIENTS: Ten critically ill, enterally fed adult patients without renal failure. INTERVENTIONS: Each patient received enteral feeding with Enrich via a nasogastric tube at 50 ml/h throughout the 5-h study period on two consecutive days. Either normal saline (control) or 10 mg of metoclopramide (treatment) was administered intravenously at the start of the study period in random order with cross-over design. MEASUREMENTS AND RESULTS: Gastric motility was measured indirectly by analysis of the absorption over time of 1.5 g of paracetamol administered into the stomach at the start of the study period together with a 100 ml bolus of Enrich feed. The rate of gastric emptying is proportional to the area under the line plot of serum paracetamol concentration against time over 120 min (AUC120). Eight of the ten patients studied showed an increased AUC120 with metoclopramide compared to that with saline. Statistical analysis with the Wilcoxon signed rank test gave a p value of 0.04, indicating a significant increase in gastric emptying following administration of metoclopramide. CONCLUSIONS: The administration of intravenous metoclopramide improved gastric emptying in a heterogeneous group of critically ill patients. Metoclopramide is a useful prokinetic drug in this patient population.

Comparison of the clinical abrasion resistance of six commercially available denture teeth.

PURPOSE: Clinical abrasion of denture teeth has certain implications when dentures are worn in excess of the average useful lifetime. The purpose of this study was to evaluate clinical denture tooth wear over a period of 3 years. MATERIAL AND METHODS: The wear of six commercially available denture teeth (Premierdent, Acrotone, vitapan, Rx1, Duravite, and Ivoclar Orthosit) and a seventh combination of teeth was compared. Seventy patients with complete dentures were divided into seven groups of 10 each to form the study population. RESULTS: There were no significant differences among the commercial denture teeth. Porcelain/Vitapan teeth exhibited the highest amount of abrasion. Significant wear was also measured between the Ivoclar Orthosit and Porcelain/Vitapan teeth.

Biostereometric quantification of clinical denture tooth wear.

In this study the wear of mandibular acrylic resin teeth opposed by porcelain maxillary teeth arranged in a lingualized occlusal scheme over a period of 3 years was measured. Six edentulous subjects received complete dentures as above and with three baseline markers of amalgam. At yearly intervals casts were made of the mandibular occlusal surfaces, including markers, and plotted by stereophotogrammetry. Volumetric loss of material was quantifiable. Ranges of 0.62-3.33 mm3/mm2 on the left side and 0.71-1.64 mm3/mm2 on the right were recorded. Friedman two-way ANOVA test indicated significant wear on teeth 35, 36, 45 and 46 but not on 34 and 44. A one-sided chewer displayed greater wear on the contralateral side, a finding difficult to explain.

Designing a transmandibular implant with the aid of biostereometric analysis.

A biostereometric survey of severely resorbed dry mandibles was used to determine whether it was possible to design a transmandibular implant that could be used for the majority of clinical situations. Computerized profiles of the relevant mandibular areas were generated and superimposed to examine the feasibility of a universal shape. It would appear that the crestal shape of the mandible between the mental foramina is on the circumference of a circle and that the surface of the inferior border is so variable that a flat surface would have to be used for a transmandibular implant. A design of a transmandibular implant is proposed on the basis of the common anatomic features of the mandible.

Compression implants: case report of a surgical, prosthetic, and cosmetic failure.

A case involving the use of non-submergible compression-type implants in an effort to rehabilitate a patient who had experienced tooth loss as a consequence of a motor vehicle accident is reported. The implants were placed in the maxillary arch without consideration of their contribution to subsequent prosthetic rehabilitation. The literature pertaining to compression-type implants is reviewed, and the difficulties related to their correct usage are delineated.

The relationship between clinical denture tooth abrasion and morphologic features of the mandible.

Biostereometric evaluation of denture tooth wear in 25 subjects was used to determine whether there was a relationship between the gonial angle, mandibular length, Frankfort-mandibular angle, and abrasion of denture teeth. The results of this study indicated no correlation could be demonstrated between any of the factors.

Three-dimensional finite element model of a human mandible incorporating six osseointegrated implants for stress analysis of mandibular cantilever prostheses.

The three-dimensional finite element stress analysis method was used to determine the distribution of stresses in and around a model of six implants which supported a typical fixed complete-arch prosthesis in a simulated human mandible. A load of 100 N was applied at different intervals along the cantilever segment. There was a decrease of stress that reached a minimal level at 15 mm along the cantilever segment. Thereafter, a progressive increase of stresses in the lingual and buccal plates was demonstrated.

Biostereometric measurement of oral tumour growth. Description of the technique and case report.

Following radiotherapy, it may be difficult to determine clinically whether tumour regression, stabilization or growth has occurred. Traditional diagnostic imaging may not be possible due to the small size of the tumour and the proximity of metallic restorations. A case of squamous cell carcinoma of the mandibular alveolar process in which these problems arose is presented. A computer-assisted biostereometric technique was used to identify volumetric change of the tumour. Polyvinylsiloxane impressions were obtained to record the anatomy of the tumour site. From these, stone models were made at four and eight weeks following radiotherapy. Using optical mapping techniques, tumour growth was demonstrated which was not evident on follow-up examinations. The methodolgy of biostereometry is presented and its advantages and potential applications are discussed.

A comparison of the bond strengths of microwave- and water bath-cured denture material.

A comparison was made of the shear bond strengths between microwave-polymerized and conventional water bath-cured polymethyl methacrylate (PMMA) bonded to denture teeth. Four groups of 15 specimens were prepared and shear bond strengths obtained by use of standardized laboratory testing methods. The results showed that microwave-cured PMMA demonstrated significantly (p 0.0001) higher bond strengths than conventional PMMA, and priming of the denture tooth surface with monomer liquid yielded significantly higher bond strengths than other surface treatment (p 0.0001).