Anesthesiology
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Comparative Study
Percutaneous lumbar sympathectomy: a comparison of radiofrequency denervation versus phenol neurolysis.
A new percutaneous approach to sympathectomy using radiofrequency denervation has seemed to offer longer duration and less incidence of postsympathetic neuralgia as compared to phenol sympathetic blocks. To compare these techniques, 17 patients underwent either phenol lumbar sympathetic blocks (n = 9) or radiofrequency denervation (n = 8). ⋯ Results indicate that 89% of patients in the phenol group showed signs of sympathetic blockade after 8 weeks, as compared to 12% in the radiofrequency group (P less than 0.05). Although the incidence of post sympathetic neuralgia appears to be less with radiofrequency denervation, further refinement of needle placement to ensure complete lesioning of the sympathetic chain will be required before the technique can offer advantages over current phenol techniques.
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Comparative Study
Comparison of the effects of isoflurane and desflurane on cardiovascular dynamics and regional blood flow in the chronically instrumented dog.
Seven mongrel dogs were chronically instrumented for the measurement of aortic and left ventricular blood pressures, cardiac output, left ventricular wall thickening, left ventricular dP/dt, and circumflex coronary, renal, hepatic and portal blood flows under the influence of desflurane (D) and isoflurane (I). Administration of the two anesthetics, was randomized, as was the order of the concentrations administered. Each dog was studied awake and at 1.2, 1.4, 1.75, and 2.0 MAC of each anesthetic on different days. ⋯ Systemic vascular resistance decreased approximately the same at 1.2 MAC (D 71, I 87%) as at 2.0 MAC (D 71, I 79%). Heart rate increased but also not in a dose-dependent fashion (percent of awake values: D 177, I 145 at 1.2 MAC, and D 176, I 155 at 2.0 MAC). Coronary blood flow was increased by both anesthetics at all concentrations (percent of awake values: I 136 at 1.2 MAC and 161 at 2.0 MAC of awake, and D 131 at 1.2 MAC and 138 at 2.0 MAC.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
The electroencephalographic effects of desflurane in humans.
The electroencephalographic (EEG) effects of a new inhaled anesthetic are of interest because of the potential of such agents to produce excitatory (convulsant) activity and because of the potential usefulness of the EEG as an indicator of anesthetic depth and cerebral activity. Accordingly, we examined the EEG in 12 healthy, young male volunteers during desflurane anesthesia. Each subject had a baseline recording and then steady-state exposure to 6, 9, and 12% (0.83, 1.24, and 1.66 MAC) desflurane in O2 alone, and to 3, 6, and 9% desflurane in O2 with 60% N2O. ⋯ Desflurane significantly suppressed EEG activity; prominent burst suppression was seen at 1.24 MAC and higher. Substitution of N2O for 0.42 MAC desflurane reduced the degree of EEG suppression relative to the equipotent administration of desflurane and O2. Quantitative EEG measures for the early doses and for the later, repeated exposures did not differ.
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Randomized Controlled Trial Clinical Trial
Effects of residual concentrations of isoflurane on the reversal of vecuronium-induced neuromuscular blockade.
Thirty-six anesthetized patients (ASA physical status 1 or 2) undergoing elective surgery were monitored (isometric adductor pollicis mechanical activity) to detect the effects of discontinuing isoflurane anesthesia upon the reversal of vecuronium-induced neuromuscular blockade. Neuromuscular blockade was produced by vecuronium 100 micrograms/kg and additional doses of 20 micrograms/kg until completion of surgery. The patients were randomly divided into three groups: in the control group (n = 12), only fentanyl/N2O was given; in the "isostable" group (n = 12), isoflurane at an end-tidal concentration of 1.25% was maintained throughout anesthesia; in the "isostop" group (n = 12), isoflurane 1.25% was discontinued before neostigmine administration. ⋯ In the isostable group, final mean train-of-four was significantly less (75%) than in the other patients (88%) (P less than 0.01). Mean tetanic fade at 100 Hz was significantly less in the isostable group (31%) than in the isostop group (57%) (P less than 0.01) and control group (84%) (P less than 0.01). We conclude that discontinuing isoflurane anesthesia for 15 min improves the reversal of a vecuronium paralysis.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
Depression of ventilation by desflurane in humans.
We studied the ventilatory effects of desflurane (formerly I-653) with and without N2O in healthy male volunteers. After insertion of venous and arterial (radial and pulmonary) catheters, baseline measurements of tidal volume (VT), respiratory rate (RR), ventilatory response to CO2, and arterial and mixed venous blood gases were made. Subjects were randomly assigned to receive either desflurane with O2 (n = 6) or with O2 and 60% N2O (n = 6). ⋯ Similarly, RR increased from 15 +/- 0.5 breaths per min awake to 32 +/- 2 breaths per min at 1.66 MAC without N2O and from 14 +/- 0.5 breaths per min awake to 40 +/- 3 breaths per min at 1.66 MAC with N2O. Desflurane without N2O depressed the ventilatory response to CO2 to 45 +/- 9, 31 +/- 5, and 11 +/- 4% of the awake values at 0.83, 1.24, and 1.66 MAC, respectively. With N2O, values were 52 +/- 14, 23 +/- 5, and 26 +/- 9% of the awake value at 0.83, 1.24, and 1.66 MAC, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)