Anesthesia and analgesia
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In this study we sought to determine the factors influencing red blood cell (RBC) transfusions and to study the transfusion practice of anesthesiologists during liver transplants. A retrospective study of 206 successive liver transplants was undertaken during a period of 52 mo. Transfused blood products were identified. Twenty variables were analyzed in a univariate fashion. For the multivariate analysis, the cases were divided in 2 subgroups: more than 4 RBC units transfused and 4 or less RBC units transfused. The average number of RBC units transfused during a liver transplant was 2.8 (+/- 3.5) per patient, 32.0% did not receive any RBC, and 19.4% did not receive any blood products during the transplant. Three variables were related to the number of RBC units transfused: the starting International Normalized Ratio value, the starting platelet count, and the duration of surgery. We found that there was a wide difference in the transfusion practice of the anesthesiologists involved in this series of liver transplants. It was difficult to identify predictive factors for RBC transfusions when the transfusion rate was small and because of the variability in human factors. Plasma transfusion did not decrease the rate of RBC transfusions; sometimes it was the contrary. ⋯ This is a retrospective study of 206 liver transplants over 52 mo to identify the predictive factors of red blood cell transfusions and the anesthesiologists' transfusion strategies. We conclude that there is a wide difference in transfusion practices among anesthesiologists.
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Anesthesia and analgesia · May 2004
Changes in splanchnic circulation during an alveolar recruitment maneuver in healthy porcine lungs.
Recruitment maneuvers (RM) are advocated as a complement to mechanical ventilation during anesthesia and in acute lung injury. However, they produce high intrathoracic pressures and volumes that may compromise hemodynamics. Our aim was to analyze the effect of a RM on hemodynamics in 10 anesthetized pigs. We assessed carotid, pulmonary, femoral, and hepatic arterial pressures, hepatic and portal venous pressures, total splanchnic (celiac trunk + superior mesenteric artery), hepatic, splenic, renal, and carotid arterial flows, and portal venous flow. We recorded hemodynamics, respiratory mechanics and blood gases before and at 8 min after RM (sustained inflation to 40 cm H(2)O of airway pressure lasting 20 s). Hemodynamics were also measured during RM, and at 1, 3, and 5 min after RM. All flows (P = 0.030) and arterial pressures (P < or = 0.048) decreased during RM, whereas venous pressures increased (P = 0.030). Flows and pressures returned to 75%-109% of baseline immediately after RM. Total splanchnic, renal and portal flows remained decreased at 8 min after RM (P < or = 0.042). Oxygenation did not change, and respiratory mechanics improved after the RM. RM produced a marked, though transitory, impairment of blood flow in all studied vessels. Despite prompt partial recovery, total splanchnic circulation remained reduced at 8 min after RM. This residual decrease may present a risk in conditions with markedly compromised circulatory reserves. ⋯ Recruitment maneuvers (RM) produce high intrathoracic pressures and volumes that may compromise hemodynamics. We found a marked transient impairment of hemodynamics during a RM in 10 anesthetized pigs. At 8 min after RM, blood flow remained reduced in the celiac trunk, superior mesenteric, and renal arteries, as well as in the portal vein. This residual decrease may present a risk in conditions with markedly compromised circulatory reserves.
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Anesthesia and analgesia · May 2004
The effect of repeated isoflurane anesthesia on spatial and psychomotor performance in young and aged mice.
Exposure to general anesthesia may contribute to postoperative cognitive impairment in elderly patients, but the relationship remains poorly understood. We investigated whether aged mice, 18-19 mo, are more susceptible to postanesthetic cognitive impairment than young mice, 3-4 mo, using spatial memory (Barnes maze) and psychomotor (rotarod) tasks. Initially we studied the effect of a single anesthetic episode on asymptotic maze performance. We then tested whether repeated anesthesia would impair spatial memory and psychomotor performance to a greater extent in aged mice. Mice were anesthetized with isoflurane (1.4% atm) for 30 min; controls received 90% oxygen. Anesthesia, administered during the asymptotic period of maze learning, did not impair performance tested the following day (P > 0.05). Repeated anesthesia, 2-3 h after each session, did not impair overall maze or rotarod performance in young or aged mice (P > 0.05). Spatial learning appeared to be facilitated by anesthesia, F(1,204) = 7.97, P < 0.01 for pooled results. Asymptotic performance-when learning had stabilized-remained unimpaired in both the maze and rotarod tasks. These results suggest that an age-related risk of anesthetic-induced impairment appears to be limited to acquisition of a novel motor skill and that anesthesia alone does not lead to prolonged cognitive impairments in aged mice. ⋯ This study demonstrates that repeated isoflurane general anesthesia impaired psychomotor performance in aged mice during the initial learning period; however, spatial learning improved and, overall, spatial memory and psychomotor performance were unimpaired. Thus, general anesthesia alone does not appear to result in prolonged cognitive deficits in aged mice.