Anesthesiology
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Comparative Study
The neuromuscular blocking and cardiovascular effects of doxacurium chloride in patients receiving nitrous oxide narcotic anesthesia.
The purpose of this study was to evaluate neuromuscular and cardiovascular effects of doxacurium chloride, a new long-acting neuromuscular blocking agent, during a stable state of nitrous oxide and narcotic anesthesia. Ninety-three ASA physical status I or II patients were studied after informed written consent had been obtained. Eighty-one patients (group A) received doxacurium. ⋯ After an ED95 dose of doxacurium the time to spontaneous recovery to 95% of control twitch height was 73.7 +/- 8.7 min. With larger doses of doxacurium, 0.04 mg.kg-1 (1.7 X ED95) and 0.05 mg.kg-1 (2.2 X ED95), the time to spontaneous recovery to 95% of control twitch height was 125.8 +/- 24.8 and 204.0 +/- 21.2 minutes, respectively. When 25% twitch height recovery or more was present the reversal of doxacurium induced neuromuscular blockade was prompt.(ABSTRACT TRUNCATED AT 250 WORDS)
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The rate of cerebrospinal fluid (CSF) formation (Vf) and resistance to reabsorption of CSF (Ra) were determined in dogs at four doses of thiopental (6, 12, 18, and 24 mg.kg-1.h-1), midazolam (0.5, 1.0, 1.5, and 2.0 mg.kg-1.h-1), and etomidate (0.86, 1.72, 2.58, and 3.44 mg.kg-1.h-1). Results were compared within and between groups and to previously reported normal values for Vf (0.030-0.054 ml/min) and Ra (220-240 cmH2O.ml-1.min) in dogs. At the two lower doses of thiopental, midazolam, or etomidate Vf was not significantly different than previously reported normal values. ⋯ With midazolam Ra was elevated at the lowest and highest doses (332 +/- 25 and 378 +/- 18 cmH2O.ml-1.min) and normal at the two intermediate doses. With etomidate Ra was normal at the three lower doses and reduced at the highest dose (187 +/- 13 cmH2O.ml-1.min). It is concluded that CSF volume may be increased and the CSF pressure at which CSF volume contracts may be increased by doses of thiopental or midazolam that increase Ra, but not increased by etomidate.
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Twenty-eight adult patients anesthetized with fentanyl, then subjected to hypothermic cardiopulmonary bypass (CPB), were studied to determine the effect of phenylephrine-induced changes in mean arterial pressure (MAP) on cerebral blood flow (CBF). During CPB patients managed at 28 degrees C with either alpha-stat (temperature-uncorrected PaCO2 = 41 +/- 4 mmHg) or pH-stat (temperature-uncorrected PaCO2 = 54 +/- 8 mmHg) PaCO2 for blood gas maintenance received phenylephrine to increase MAP greater than or equal to 25% (group A, n = 10; group B, n = 6). To correct for a spontaneous, time-related decline in CBF observed during CPB, two additional groups of patients undergoing CPB were either managed with the alpha-stat or pH-stat approach, but neither group received phenylephrine and MAP remained unchanged in both groups (group C, n = 6; group D, n = 6). ⋯ In patients in group A CBF was unchanged as MAP rose from 56 +/- 7 to 84 +/- 8 mmHg. In patients in group B CBF increased 41% as MAP rose from 53 +/- 8 to 77 +/- 9 mmHg (P less than 0.001). During hypothermic CPB normocarbia maintained via the alpha-stat approach at a temperature-uncorrected PaCO2 of approximately equal to 40 mmHg preserves cerebral autoregulation; pH-stat management (PaCO2 approximately equal to 57 mmHg uncorrected for temperature, or 40 mmHg when corrected to 28 degrees C) causes cerebrovascular changes (i.e., impaired autoregulation) similar to those changes produced by hypercarbia in awake, normothermic patients.