Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1997
Randomized Controlled Trial Clinical TrialIntrathecal fentanyl with small-dose dilute bupivacaine: better anesthesia without prolonging recovery.
Recent concern regarding lidocaine neurotoxicity has prompted efforts to find alternatives to lidocaine spinal anesthesia. Small-dose dilute bupivacaine spinal anesthesia yields a comparably rapid recovery profile but may provide insufficient anesthesia. By exploiting the synergism between intrathecal opioids and local anesthetics, it may be possible to augment the spinal anesthesia without prolonging recovery. Fifty patients undergoing ambulatory surgical arthroscopy were randomized into two groups receiving spinal anesthesia with 3 ml 0.17% bupivacaine in 2.66% dextrose without (Group I) or with (Group II) the addition of 10 microg fentanyl. Median block levels reached T7 and T8, respectively (P = not significant [NS]). Mean times to two-segment regression, S2 regression, time out of bed, time to urination, and time to discharge were 53 vs 67 min (P < 0.01), 120 vs 146 min (P < 0.05), 146 vs 163 min (P = NS), 169 vs 177 min (P = NS), and 187 vs 195 min (P = NS) respectively. Motor blockade was similar between groups, but sensory blockade was significantly more intense in Group II (P < 0.01). Six of 25 blocks failed in Group I, whereas none failed in Group II. The addition of 10 microg fentanyl to spinal anesthesia with dilute small-dose bupivacaine intensifies and increases the duration of sensory blockade without increasing the intensity of motor blockade or prolonging recovery to micturition or street fitness. ⋯ Concerns about the neurotoxicity of lidocaine have prompted efforts to find alternatives to lidocaine spinal anesthesia. We studied 50 patients undergoing ambulatory surgical arthroscopy and found that although small-dose bupivacaine alone is inadequate for this procedure, the addition of fentanyl makes it reliable.
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Anesthesia and analgesia · Sep 1997
Comparative StudyDose-response and time course of effect of rocuronium in male and female anesthetized patients.
To determine differences from dose-response and time-course of rocuronium between male and female patients, 60 adult patients (30 male and 30 female), ASA grade I, aged 17-52 yr, undergoing elective plastic surgery were studied. Anesthesia was maintained with 60% nitrous oxide in oxygen, thiopental, and incremental doses of fentanyl as required. Neuromuscular function was assessed mechanomyographically with train-of-four (TOF) stimulation at the wrist every 12 s, and the percentage depression of the T1 response was used as the study variable. The dose-response relationship of rocuronium was determined by a cumulative dose-response technique. The results showed that the dose-response curve of rocuronium in the men was shifted to the right, indicating a decrease in the sensitivity to rocuronium-induced neuromuscular block versus the women. The 50%, 90%, and 95% effective doses of rocuronium were 178.4 +/- 53.7, 358.7 +/- 101.3, and 386.2 +/- 113.4 microg/kg, respectively, in male patients, and 128.8 +/- 42.5, 252.8 +/- 51.7, and 274.4 +/- 59.4 microg/kg in female patients. After an intravenous administration of total dose of 400 microg/kg rocuronium, neuromuscular block was significantly longer in the men than in the women. The duration of peak effect, clinical duration, and total duration were 6.5 +/- 3.0, 12.5 +/- 4.9, and 33.6 +/- 8.7 min, respectively, in male patients, and 11.8 +/- 2.7, 18.5 +/- 5.3, and 46.8 +/- 9.6 min in female patients. We conclude that women were approximately 30% more sensitive to rocuronium compared with men. ⋯ The authors found that women were 30% more sensitive to rocuronium than men. This suggests that the routine dose of rocuronium should be reduced in women compared with men.
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Anesthesia and analgesia · Sep 1997
Randomized Controlled Trial Clinical TrialSimulation of an epidural test dose with intravenous isoproterenol in isoflurane-anesthetized adults.
Although a simulated intravenous (I.V.) test dose containing 3 microg isoproterenol results in a reliable heart rate (HR) increase in anesthetized patients, hypotension may limit its clinical utility. The present study was designed to determine the incidence of hypotension and the reliability of smaller doses of isoproterenol. Forty-five healthy adult patients were anesthetized with 1% end-tidal isoflurane and nitrous oxide after endotracheal intubation and were randomized to one of three groups according to the dose of isoproterenol. Isoproterenol 1-, 2-, and 3-microg groups (n = 15 each) received 3 mL of 1.5% lidocaine with 1, 2, and 3 microg isoproterenol I.V., respectively, to simulate an intravascularly administered test dose. HR and systolic blood pressure were measured at 20-s intervals for 4 min after injection. Mean maximal HR increases were 15 +/- 6, 23 +/- 10, and 32 +/- 7 bpm (mean +/- SD) in the isoproterenol 1-, 2-, and 3-microg groups, respectively. However, the incidence and degree of systolic hypotension were similar among groups. Isoproterenol 3 microg produced 100% sensitivity in both the conventional (> or = 20 bpm increase) and the modified (> or = 10 bpm increase) HR criteria, but 2 microg resulted in 100% sensitivity on the modified criterion alone. Isoproterenol 1 microg did not elicit reliable HR changes. Significant correlation was demonstrated between the isoproterenol dose (microg/kg) and the maximal HR increase. Ninety-five percent confidence intervals to increase HR by 10 and 20 bpm were 0.015-0.02 microg/kg and 0.03-0.04 microg/kg, respectively. The application of isoproterenol as a test dose component seems promising, pending detailed studies of neural toxicity. The appropriate dose needs to be tailored according to the patient's weight. ⋯ To determine whether an epidural catheter may be in a blood vessel, various vasoactive drugs are often administered. The author found that isoproterenol might be a useful drug in place of epinephrine.
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Anesthesia and analgesia · Sep 1997
Comparative StudyThe impact of choice of muscle relaxant on postoperative recovery time: a retrospective study.
To test the hypothesis that the use of long-acting muscle relaxants is associated with prolonged postoperative recovery when compared with the use of shorter-acting relaxants, we undertook a retrospective study of 270 patients with induced paralysis recovering from general anesthesia. We calculated the mean recovery time associated with each muscle relaxant used. Regression analyses were performed to control for potential confounding of the results by length and type of surgery, as well as age and sex. Taking these into account, the adjusted difference in mean recovery time between patients receiving short- and intermediate-acting relaxants (mivacurium, atracurium, and vecuronium) versus those receiving long-acting relaxants (d-tubocurarine, pancuronium, and pancuronium and d-tubocurarine combination) was 30 min (95% confidence interval [CI] 8-53). The adjusted difference in mean recovery time between patients receiving vecuronium and those receiving pancuronium (i.e., the single most frequently used drug in each category) was 33 min (95% CI 1-66). Shortened recovery time accounted for an estimated average $37.95 decrease in recovery room charge per patient when vecuronium was used instead of pancuronium, versus a $22.84 increase in drug cost. Our data and analyses support the hypothesis that the use of long-acting muscle relaxants is associated with prolonged recovery after surgery and provide preliminary evidence that restricting the use of the more expensive, shorter-acting muscle relaxants may represent a false economy. ⋯ In this retrospective study, the use of old-fashioned, inexpensive, long-acting paralyzing drugs was found to be associated with prolonged postoperative recovery. This has implications when deciding whether, as an economic measure, to restrict the use of the more expensive, shorter-acting paralyzing drugs, because prolonged recovery also has a price.
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Anesthesia and analgesia · Sep 1997
Comparative StudyA comparative study of the vasodilator effects of prostaglandin E1 in patients with pulmonary hypertension after mitral valve replacement and with adult respiratory distress syndrome.
To determine whether the vasodilator effects of prostaglandin E1 (PGE1) differ according to the etiology and pathophysiology of pulmonary hypertension, we studied 30 patients with pulmonary hypertension after mitral valve replacement (MVR) (n = 16) or with the adult respiratory distress syndrome (ARDS) (n = 14). PGE1 was administered to decrease the mean pulmonary artery pressure to below 30 mm Hg in both groups. Cardiac index and oxygen delivery tended to increase, whereas mean systemic artery pressure, mean pulmonary artery pressure, systemic vascular resistance index (SVRI), and pulmonary vascular resistance index (PVRI) significantly decreased in both groups. A vasodilatory index was defined in this study to allow evaluation of vasodilation relative to PGE1 dose: systemic vasodilatory index (VIs) = SVRI change/PGE1 dose; and pulmonary vasodilatory index (VIp) = PVRI change/PGE1 dose. The VIp was similar in both groups, but the VIs was significantly greater in the ARDS group compared with the MVR group (13.3 +/- 7.8 vs 4.8 +/- 5.1, P < 0.01). A good correlation was found between the pretreatment intrapulmonary shunt fraction (Qs/Qt [%]) value and PGE1 extraction rate in the lung (r = 0.60), and between the pretreatment Qs/Qt value and PGE1 concentration in the radial artery (r = 0.65) in an additional 15 patients. We conclude that the vasodilator effects of PGE1 on the pulmonary circulation are similar in the two groups, whereas the vasodilator effects on the systemic circulation are significantly greater in the ARDS group and that significant reduction in VIs in the ARDS group was associated with decreased PGE1 extraction in the lung. ⋯ Pulmonary hypertension after mitral valve replacement, or with adult respiratory distress syndrome, is a major medical problem. The authors found that administration of prostaglandin E1 significantly dilated the pulmonary circulation with a concomitant decrease in pulmonary artery pressure. Because the systemic vasodilatory effect was greater in the adult respiratory distress syndrome group, the authors concluded that prostaglandin E1 concentrations in the systemic circulation depend on the severity of lung injury.