The Journal of surgical research
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Norepinephrine (NE) is used clinically to increase oxygen delivery (DO2) by increasing cardiac output (CO). The rate of administration of NE is usually based on frequent measurements of blood pressure (BP) and infrequent measurements of CO with little regard for oxygen delivery or consumption dynamics. Although the ultimate goal of an inotropic drug is to increase DO2 in excess of metabolic requirements (VO2), the effect of NE on the DO2/VO2 ratio has not been previously studied. ⋯ However, the increase in DO2 minimally exceeded the increase in VO2 at lower doses of NE and the relative increase in VO2 exceeded the change in DO2 at a dose of 0.04 microgram/kg/min. Minimal advantage to oxygen utilization physiology at low doses of NE and a potential deleterious effect at a dose of 0.04 microgram/kg/min were observed, therefore, despite associated increases in mean systemic blood pressure. The effectiveness of NE administration could be most effectively monitored by the mixed venous oxygen saturation (SVO2), rather than by intermittent assessment of BP, CO, or DO2.(ABSTRACT TRUNCATED AT 250 WORDS)
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The myocardial response to catecholamines is significantly diminished in many types of shock or heart failure. The guinea pig heart is an ideal model for the study of shock, as it is relatively inexpensive, and the cardiovascular system of the guinea pig most closely resembles that of the human. Using this model, we have developed techniques to characterize and quantitate changes in beta-adrenergic receptors (beta AR) in the guinea pig heart after burn injury. ⋯ The membrane preparations used in this study bound both agonists and antagonists with a rank order of potency and stereospecificity characteristic of a beta-adrenergic receptor. Finally, agonist competition curves were performed with isoproterenol in the presence and absence of Gpp(NH)p to determine receptor regulation by the Gs protein. Analysis using computer-assisted techniques suggests that the fraction of high-affinity beta-receptors is significantly reduced after burn injury (41.2 +/- 4.7%) compared to sham-burned controls (54 +/- 2%, P < or = 0.023).(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study Clinical Trial Controlled Clinical Trial
Bioimpedance hemodynamics compared to pulmonary artery catheter monitoring during orthotopic liver transplantation.
Simultaneous cardiac output measurements were obtained using bioimpedance (BI) and thermodilution (TD) methods in 10 patients undergoing orthotopic liver transplantation (OLT). BI and TD data were collected during five intraoperative phases of OLT. ⋯ Sv-O2 correlated poorly with cardiac index determined by TD (r = 0.41) or BI (r = .47). BI is an accurate reproducible method for measuring cardiac output and may be a useful adjunct to the pulmonary artery catheter for hemodynamic monitoring during OLT.
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This study was undertaken to evaluate the effect of a cyclooxygenase inhibitor, ibuprofen, at various time intervals in a live Escherichia coli model of canine septic shock. Group I (control) animals (n = 5) received a LD100 dose of 10(9) live E. coli per kilogram were given no further treatment. Group II animals (n = 5) received a 10 mg/kg bolus of ibuprofen 10 min prior to bacterial infusion. ⋯ Plasma levels of tumor necrosis factor (TNF) and interleukin-6 (IL-6) were significantly elevated (P less than 0.05) from baseline in all animals (Groups I, II, and III), but ibuprofen treatment failed to either increase or decrease these levels. This study demonstrates that ibuprofen treatment can significantly reverse the deleterious hemodynamic and metabolic effects commonly seen in live E. coli septic shock without depressing the endogenous production of TNF or IL-6. These data support the hypothesis that sepsis initiates a cascade of mediators with the cytokines TNF and IL-6 being proximal events which in turn stimulate the next level, with ibuprofen probably exerting its inhibitory effect distal to this point in the cascade.
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Clinical and basic studies have documented a high susceptibility to pneumococcal infection in asplenic humans and animals. It has been suggested that autotransplantation of splenic tissue might be a method of providing host resistance when total splenectomy is necessary. However, the effect of splenic autograft has remained controversial. ⋯ Intraperitoneal and intramuscular implanted rats did not show a significant difference from the splenectomized rats. More than 50% of splenic tissue for autograft showed a significant increase in pneumococcal clearance and survival rate as compared with that of splenectomized rats. It was suggested that the most effective site of autotransplantation is the omental pouch and approximately 50% of the whole spleen would be necessary for prevention from sepsis.