Anesthesia and analgesia
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Anesthesia and analgesia · Feb 1996
Randomized Controlled Trial Comparative Study Clinical TrialHemodynamic effects of spinal anesthesia in the elderly: single dose versus titration through a catheter.
Sixty elderly patients (> 70 yr old) undergoing surgery for hip fracture were prospectively studied in order to compare hemodynamic tolerance of titrated doses of hyperbaric bupivacaine using continuous spinal anesthesia (CSA) versus single-dose spinal anesthesia (SDSA). Patients were randomized into two groups (CSA group: n = 30; SDSA group: n = 30). The SDSA patients received 10-15 mg of 0.5% hyperbaric bupivacaine (based on age and height), and the CSA patients received a starting dose of 5 mg of 0.5% hyperbaric bupivacaine, followed after 15 min by optional reinjection of 2.5 mg every 5 min until a T10 level sensory block was reached. ⋯ The mean dose of ephedrine was significantly less in the CSA group (1.8 +/- 0.7 mg, administered to only 37% of patients) than in the SDSA group (19.4 +/- 3.3 mg administered to all patients, P < 0.0001). No late complications related to the spinal anesthesia technique were observed in either group. We concluded that CSA, using small titrated doses of 0.5% hyperbaric bupivacaine, is safe, efficient, and provides better hemodynamic stability than SDSA in elderly patients.
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Anesthesia and analgesia · Feb 1996
The influence of carbon dioxide and body position on near-infrared spectroscopic assessment of cerebral hemoglobin oxygen saturation.
Near-infrared spectroscopy may allow continuous and noninvasive monitoring of regional brain hemoglobin oxygen saturation by measuring the differential absorption of infrared light by oxyhemoglobin and deoxyhemoglobin. We have previously examined the correlation between the spectroscopic signal generated by a prototype cerebral oximeter (Invos 3100; Somanetics, Troy, MI), and global brain hemoglobin oxygen saturation calculated from arterial and jugular venous bulb oxygen saturations. Because the technology does not distinguish between arterial and venous hemoglobin saturation, changes in the proportion of cerebral arterial and venous blood volume, which may result from changes in blood flow or venous distending pressure, may confound measurements. ⋯ We found that changes in position did not influence the association between CSfO2 and CScombO2 (r2 = 0.69-0.885) during hypoxic challenge. In a second set of eight volunteers, we studied the influence of hypercapnia and hypocapnia and body position on the association between CSfO2 and CScombO2, and found that they were less well correlated (r2 = 0.366-0.976) in individual patients. Because changes in body position and Paco2 confound the relationship between CSfO2 and CScombO2, changes in CSfO2 can best be assessed if position and Paco2 are constant.
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Anesthesia and analgesia · Feb 1996
Repeated dural punctures increase the incidence of postdural puncture headache.
Previous studies have failed to find a significant correlation between the number of dural punctures and the incidence of postdural puncture headache (PDPH), questioning the hypothesis that leakage of cerebrospinal fluid (CSF) through the dural tear is the cause of PDPH. We hypothesized that insufficient statistical power of these studies was the cause for this unexpected finding, and re-examined whether repeated dural punctures increase the incidence of PDPH by analyzing prospectively collected data on 8034 spinal anesthetics. Uneventful spinal anesthetics, including a single subarachnoid injection of local anesthetics, occurred in 7865 (97.9%) cases, whereas failed spinal anesthetics requiring repeated dural puncture for a second subarachnoid injection of local anesthetics occurred in 165 (2.1%) cases. ⋯ We found that repeated dural punctures significantly increased the incidence of PDPH. We conclude that increased risk of PDPH is a disadvantage of performing a second subarachnoid injection of local anesthetics after a failed spinal anesthetic. Moreover, this result suggests that leakage of CSF through the dural tear is the most plausible cause of PDPH.
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Anesthesia and analgesia · Feb 1996
Bupivacaine plasma concentrations during continuous epidural anesthesia in infants and children.
Venous bupivacaine plasma concentrations were measured in six neonates and infants aged 4 days to 3.9 mo (mean, 2.1 mo) and 10 infants and children aged 9 mo to 6 yr (mean, 3.1 yr) after administration of an initial bolus of 0.5 mL/kg bupivacaine 0.25%, followed by a continuous infusion of local anesthetic (0.25 mL.kg-1.h-1) over a period of 4 h (first hour: bupivacaine 0.25%, then reduced to 0.125%). Plasma concentrations of local anesthetic measured at 180 min and 300 min after beginning of bupivacaine administration were significantly higher in younger infants when compared to older infants and children (180 min: 0.67 +/- 0.24 micrograms/mL [0.25-0.97] vs 0.27 +/- 0.11 micrograms/mL [0.19-0.55], P < 0.01; 300 min: 0.86 +/- 0.36 micrograms/mL [0.35-1.25] vs 0.34 +/- 0.12 micrograms/mL [0.18-0.57], P < 0.01). The results of our study show that despite applying the same dosage of epidural bupivacaine significantly higher plasma concentrations were seen after short periods of continuous infusion in infants up to 4 mo than in children older than 9 mo.