Liver transplantation : official publication of the American Association for the Study of Liver Diseases and the International Liver Transplantation Society
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Part 1 of our report, presented in the same issue of the Journal, shows that immediate postoperative extubation and direct transfer to the surgical ward is safe and reduces reliance on the intensive care unit in most liver transplant recipients. However, there is no method to preoperatively predict which patients will need ventilatory support after surgery. To address this issue, we examined the relationship between perioperative patient attributes and extubation outcome in patients entered into our immediate postoperative extubation study from 1996 to 1998. ⋯ Female sex (P =.02), BMI of 32 or greater (P =.015), portosystemic shunt (P =.022), and encephalopathy (P =.041) were associated with no attempt by the physician to extubate, whereas encephalopathy (P =.01) and BMI of 34 or greater (P =.002) were associated with failure to meet criteria for postoperative extubation (described in part 1 of this study). We conclude there are limited factors that predict an increased risk for postoperative respiratory failure in liver transplant recipients. Our results indicate that physicians are conservative in their approach to extubation immediately after surgery, and sole reliance on physician judgment to determine suitability for postoperative extubation leads to unnecessary use of postoperative cardiopulmonary support.
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Postoperative ventilation and admission to the intensive care unit (ICU) is the standard of care in liver transplantation and comprises a significant proportion of transplantation costs. Because immediate postoperative extubation has been reported previously in a selected group of liver transplant recipients, we questioned whether this protocol could be extended to a larger group of patients. We also sought to determine the proportion of patients extubated immediately after surgery that could be transferred to the surgical ward without intervening ICU care. ⋯ A learning curve detected during the 3-year study period showed that attempts to extubate increased from 73% to 96% and triage to the surgical ward increased from 52% to 82% without compromising patient safety. The use of this protocol in our institution resulted in a 1-day reduction in ICU use in 75.5% of study subjects. We therefore conclude that the majority of liver transplant recipients can be extubated safely and admitted to the surgical ward after liver transplantation surgery, thus decreasing the cost associated with ICU care.
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Microdialysis provides the opportunity to continuously monitor metabolic changes in tissue. The aim of the study is to monitor metabolic changes in the liver graft over time during transplantation in a pig model. Fourteen littermate female pigs with a body weight of 30 to 34 kg were used for seven orthotopic liver transplantations. ⋯ During rewarming, it showed an accelerated increase, but after reperfusion, it decreased rapidly. Rewarming and reperfusion are most harmful to the liver, reflected by an accelerated increase in glucose and glycerol levels and lactate-pyruvate ratio. High intrahepatic glucose levels during ischemia appear to be a liver-specific event, which may represent glycogen degradation in injured hepatocytes.
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Hepatopulmonary syndrome, arterial hypoxemia caused by intrapulmonary vasodilatation, occurs in approximately 10% of patients with cirrhosis. The severity of hypoxemia affects liver transplant candidacy and is associated with increased morbidity and mortality posttransplantation. Screening guidelines for detecting the presence of arterial hypoxemia do not exist. ⋯ An SpO(2) of 94% or less detected all subjects with an arterial PaO(2) less than 60 mm Hg. Pulse oximetry significantly overestimates arterial oxygenation, and the inaccuracy is not influenced by liver disease. Nevertheless, pulse oximetry can be a useful screening tool to detect arterial hypoxemia in patients with cirrhosis, but a higher threshold for obtaining an ABG must be used.
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Swelling of cerebral glial cells is a characteristic complication in patients with acute liver failure (ALF). This astrocyte edema may result in high intracranial pressure (ICP) and brain herniation before or during liver transplantation. Metabolic alterations responsible for the development of high ICP in patients with ALF are not fully understood. ⋯ Instead, we found that [lactate](ec) levels correlated in this patient with arterial lactate concentrations during and after grafting (r(2) = 0.96; P <.05), but did not correlate with arterial glucose concentrations (r(2) = 0.20; P = not significant). Also, [glutamate](ec) and [glycerol](ec) levels were severely elevated before liver transplantation, but tended to decrease in the hours after grafting. These findings indicate disturbances in glutamate neurotransmission, arachidonic acid metabolism, and lactate flux across the blood-brain barrier in patients with ALF.