The impact of continuous renal replacement therapy on drug therapy.

Critically ill patients with multisystem organ failure often require daily administration of large volumes of fluid to provide electrolyte and nutrition support, medications, and blood products. This often results in fluid overload, which has historically been managed with intermittent hemodialysis (IHD). Unfortunately, IHD entails a high rate of fluid and solute removal that often exacerbates hemodynamic instability. Accordingly, continuous renal replacement therapy (CRRT), involving slow and continuous removal of water and solutes from the plasma, is currently preferred for managing these patients.

Increasing doses of pentoxifylline as a continuous infusion in canine septic shock.

We investigated effects of pentoxifylline during septic shock. Two-year-old (10-12 kg), purpose-bred beagles were infected i.p. with Escherichia coli 0111:B4 (1.2-1.5 x 10(9) colony-forming units per kilogram b.wt.) in a fibrin clot and then immediately treated with one of five doses of pentoxifylline (0.5-20 mg. kg-1. h-1 i.v.) as a 36-h continuous infusion or placebo. All animals received antibiotics and fluid resuscitation. Pentoxifylline levels increased in a dose-dependent manner during (p =.001) and were undetectable 12 h after stopping the infusion. During infusion of pentoxifylline at all doses, there were increases (p =.003), and once the infusion was stopped, there were decreases (p =.049) in endotoxin levels compared with controls. After clot implantation, at all pentoxifylline doses there was a significant increase in tumor necrosis factor levels, compared with controls (p =.025). The relative risk of death was significantly increased with pentoxifylline therapy in a dose-dependent fashion (20 >/= 10 >/= 5.0 >/= 1.0 >/= 0.5 mg. kg-1, p =.008). One hypothesis consistent with these data is that high pentoxifylline levels slowed endotoxin clearance, resulting in high levels of endotoxemia and increased proinflammatory mediator release and death. Pentoxifylline, used as a long-term continuous infusion as is commonly done clinically, can be harmful during Gram-negative septic shock.

Pharmacokinetics of fentanyl during hyperthermic, isolated lung perfusion.

BACKGROUND: Hyperthermic, isolated pulmonary perfusion with tumor necrosis factor is a surgical procedure that isolates the pulmonary vasculature from the systemic circulation in patients with unresectable primary or metastatic disease confined to the chest. High drug levels are delivered to the perfused organ, avoiding systemic toxicity, and preventing loss of active drug through metabolism. METHODS: The pharmacokinetics of fentanyl are evaluated in three patients while the operative lung is hyperthermic, ventilated, and perfused with an asanguineous solution during nonpulsatile bypass. A loading dose of fentanyl, 1.5 microg/kg to 2.5 microg/kg, was given during the induction of anesthesia followed by a continuous infusion of 150 microg/hr. RESULTS: Results showed no difference in mean plasma fentanyl concentrations before, during, or after bypass and was consistent with clearance values previously reported in healthy adult surgical patients in the absence of an extracorporeal circuit. CONCLUSIONS: Adjustments in fentanyl dosing are not required before, during, or after hyperthermic, isolated pulmonary perfusion is established and a steady state of fentanyl is achieved.

Neuromuscular blocking agents in critical care.

Neuromuscular blocking agents have been used in critically ill patients for over 30 years. Recently, the pharmacology, monitoring, and toxicity of these agents have received much attention. This article reviews the pharmacology, indications, monitoring parameters, and toxicity of the neuromuscular blocking agents commonly used in the intensive care unit.