Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1993
Effect of phenylephrine bolus administration on left ventricular function during high thoracic and lumbar epidural anesthesia combined with general anesthesia.
The effect of phenylephrine (PHE) boluses on left ventricular (LV) function was examined in patients without cardiovascular disease who developed arterial hypotension during high thoracic epidural anesthesia (TEA) combined with general anesthesia (GA) (group 1) or lumbar epidural anesthesia (LEA) combined with GA (group 2). LV function was assessed by transesophageal echocardiography (TEE) before and after central venous injection of 1 microgram/kg PHE. Fractional diameter shortening (FDS), end-systolic wall stress (ESWS), and rate-corrected velocity of circumferential fiber shortening (mVcfc) were determined. ⋯ FDS was reduced from 38% to 25% (mean, P < 0.01) in group 1 and remained unchanged in group 2. ESWS increased from 70 to 143 x 10(3) dyne.cm-2 (P < 0.01) and from 57 to 86 x 10(3) dyne.cm-2 (P < 0.05), in groups 1 and 2, respectively. mVcfc was significantly reduced from 1.11 to 0.80 circ/s (P < 0.05) in group 1 and was not altered in group 2. The authors conclude that PHE given as an intravenous bolus to patients under high TEA plus general anesthesia causes a transient impairment of LV function.
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Anesthesia and analgesia · Mar 1993
The effect of head-down tilt on arterial blood pressure after spinal anesthesia.
We examined the usefulness of 10 degrees head-down tilt for hypotension after spinal block. Two different investigations were performed, one employing head-down tilt after arterial blood pressure had decreased (n = 40), and the other using a prophylactic tilt (n = 50). When the head-down tilt was applied to treat hypotension after spinal block (n = 40), arterial blood pressure increased only in patients whose systemic blood pressure decreased more than 30% from the control (severe hypotension group, n = 11). ⋯ When the head-down tilt was performed immediately after spinal block (n = 24), the changes in systolic blood pressure were the same as in the horizontal group (n = 26). The cephalad spread of analgesia at 20 min after spinal block was higher, however, in the head-down tilt group (T3.8 +/- 1.6) than the horizontal group (T5.2 +/- 1.9). From these results we conclude that head-down tilt for hypotension after spinal block increases arterial blood pressure only for severe hypotension, and that prophylactic head-down tilt has no effect in maintaining blood pressure.
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Anesthesia and analgesia · Mar 1993
Clinical TrialProlonged administration of isoflurane to pediatric patients during mechanical ventilation.
We undertook a prospective study of the effectiveness and potential toxicities of isoflurane sedation in pediatric patients undergoing mechanical ventilation who required large doses of opioids for sedation were considered eligible. Ten patients (ages 3 wk to 19 yr) received continuous isoflurane sedation for a mean duration of 131 minimum alveolar concentration (MAC)-hours (range 13-497 MAC-hours). The mean peak inorganic fluoride (F-) concentration was 11.0 microM, and the highest F- concentration was 26.1 microM after 441 MAC-hours. ⋯ Five patients demonstrated an abstinence syndrome which consisted of nonpurposeful movements and extreme agitation. All of these patients had received at least 70 MAC-hours of isoflurane. Our experience indicates that isoflurane can effectively provide sedation to pediatric patients for prolonged periods without significant adverse effects on cardiovascular, hepatic, or renal function.
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Anesthesia and analgesia · Mar 1993
Comparative StudyToxicity of bupivacaine encapsulated into liposomes and injected intravenously: comparison with plain solutions.
The acute central nervous system and cardiac toxicities of 0.25% bupivacaine, without adrenalin, encapsulated in multilamellar liposomes were compared with 0.25% plain solutions with and without adrenalin after intravenous infusion at a rate of 0.15 mg.kg-1 x min-1 with an increase of 0.036 mg.kg-1 x min-1 every 10 min. Three groups of six anesthetized, unventilated rabbits were studied. The doses of bupivacaine (in mg.kg-1) which produced seizure, ventricular tachycardia, and asystole were determined. ⋯ A statistical comparison of the cumulative lethal doses of bupivacaine 0.25% with adrenalin and of liposomal bupivacaine led to a P = 0.06. Adrenalin did not modify the systemic toxicity of the local anesthetic. This study showed a reduction of nervous and cardiac toxicity of bupivacaine encapsulated in multilamellar liposomes when infused intravascularly.
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Anesthesia and analgesia · Mar 1993
Right ventricular function during orthotopic liver transplantation.
Right ventricular (RV) function was assessed in 20 patients undergoing orthotopic liver transplantation to determine its role in the hemodynamic instability frequently seen during this procedure. A modified pulmonary artery catheter equipped with a fast response thermistor was used to determine RV ejection fraction (EFrv), allowing for calculation of RV end-diastolic volume index (EDVIrv, as the ratio of stroke index [SI] to EFrv) and RV end-systolic volume index (ESVIrv, as the difference between EDVIrv and SI). The above hemodynamic measures were taken during dissection for hepatectomy (stage I), during the anhepatic stage (stage II), and after reperfusion of the grafted liver, the neohepatic stage (stage III). ⋯ RV function appeared to be well preserved throughout the procedure, as indicated by a relatively constant and supranormal EFrv, although a small and probably clinically unimportant decrease in EFrv was observed during the anhepatic stage (0.52, 0.50, and 0.55 during stages I, II, and III, respectively). There was a strong correlation between SI and EDVIrv for pooled data over a wide range of EDVIrv (60-185 mL.m-2). Although unstable central blood temperature precluded the determination of EFrv within the first 5 min after reperfusion, RV function was unaltered otherwise during uncomplicated orthotopic liver transplantation using venovenous bypass, indicating that orthotopic liver transplantation per se is not associated with significant RV dysfunction.