Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Clinical TrialNitrous oxide enhances the level of sensory block produced by intrathecal lidocaine.
We examined the effect of nitrous oxide (N2O) administration on the level of sensory block produced by intrathecal lidocaine in patients undergoing transurethral procedures. Twenty minutes after subarachnoid injection of 100 mg (5%) hyperbaric lidocaine, the level of block to pressure sensation was assessed. After establishing the baseline sensory block, patients were randomly assigned to receive either 50% nitrogen (control group) or 50% N2O in oxygen for 10 min, and the sensory level was reassessed. All patients then received 35% oxygen for 5 min, and the level of block to pressure was assessed again. Changes were measured in centimeters and standardized by dividing those results by the height of patients (in centimeters). Ten minutes after nitrogen or N2O administration, a 3.8-cm regression of sensory block was found in the control group, and a 1.8-cm cephalad increase was found in the treatment group (P < 0.0001). Discontinuation of N2O for 5 min resulted in a rapid regression of the level of sensory block (4 cm in the N2O group versus 1.9 cm in the control group, P < 0.0001). However, 5 min after discontinuation of N2O, the overall regression of the sensory block in the control group, when measured from the baseline, was 5.7 cm versus 2.2 cm in the N2O group (P < 0.001). The differences between the two groups before standardization are consistent with those after standardization (t = 9.02 at 10 min, t = 4.24 at 15 min, and t = 3.97 for the overall change at 15 min). The results suggest that inhalation of 50% N2O enhances the level of sensory block produced by intrathecal lidocaine. ⋯ We measured the level of sensory block produced by subarachnoid anesthesia with lidocaine before and after inhalation of 50% nitrous oxide for 10 min. Nitrous oxide enhanced the level of subarachnoid anesthesia with minimal hemodynamic effects. These findings are of clinical importance when subarachnoid anesthesia subsides before the completion of surgery.
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Clinical TrialAttenuation of cardiovascular responses to tracheal extubation: comparison of verapamil, lidocaine, and verapamil-lidocaine combination.
We recently showed that verapamil attenuated hemodynamic responses to tracheal extubation. The aim of the current study was to compare the efficacy of a combination of intravenous (I.V.) verapamil (0.1 mg/kg) and I.V. lidocaine (1 mg/kg) with that of each drug alone in suppressing the cardiovascular changes during tracheal extubation and emergence from anesthesia. One hundred adult patients (ASA physical status I) who were to undergo elective minor surgery were randomly assigned to one of four groups (n = 25 each): Group S = saline plus saline (control), Group V = verapamil 0.1 mg/kg I.V. plus saline, Group L = lidocaine 1 mg/kg I.V. plus saline, and Group V-L = verapamil 0.1 mg/kg I.V. plus lidocaine 1 mg/kg I.V. These medications were given 2 min before tracheal extubation. Anesthesia was maintained with 1.0%-2.0% sevoflurane and 60% nitrous oxide (N2O) in oxygen. Muscle relaxation was achieved with vecuronium, and a residual neuromuscular blockade was reversed with neostigmine 0.05 mg/kg (combined with atropine 0.02 mg/kg). Changes in heart rate (HR) and arterial blood pressure (AP) were measured during and after tracheal extubation. In the control group, the HR and systolic and diastolic AP increased significantly during tracheal extubation. Verapamil, lidocaine, and their combination attenuated the increases in these variables. The beneficial effect was the greatest with the combination of verapamil and lidocaine. These findings suggest that verapamil 0.1 mg/kg and lidocaine 1 mg/kg given I.V. concomitantly 2 min before tracheal extubation is a simple and more effective prophylaxis than verapamil or lidocaine alone for attenuating the cardiovascular changes associated with tracheal extubation. ⋯ Tachycardia and hypertension associated with tracheal extubation, which may lead to myocardial ischemia, represent a potential risk for patients with coronary arterial disease. To seek effective pharmacological prophylaxis against these complications, we compared the attenuation of hemodynamic changes among verapamil, lidocaine, and a verapamil/lidocaine combination using ASA physical status I patients and found the combination to be effective.
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Anesthesia and analgesia · Nov 1997
Is epidural anesthesia in labor associated with chronic low back pain? A prospective cohort study.
The association between epidural anesthesia during labor and subsequent postpartum low back pain remains unclear. The objective of this follow-up cohort study was to determine whether epidural anesthesia was associated with chronic back pain 1 yr after delivery. We contacted 329 women by telephone and asked them to complete a standardized questionnaire 1 yr (+/-1 mo) after delivery. One hundred sixty-four women had received epidural analgesia for labor and delivery, and 165 had not. Subjects were asked to quantify their back pain (yes/no, numeric rating score, and interference with daily activities). Differences between the two groups were tested by using the chi2 test and the Mann-Whitney U-test, and logistic regression was used to control for confounding variables. The response rate was 244 of 329 (74%). Responders and nonresponders were similar in their demographic and clinical characteristics. There was no difference in the prevalence of back pain between women who had received epidural anesthesia (12 of 121, 10%) and those who had not (17 of 123, 14%). The adjusted relative risk of low back pain at 1 yr (epidural versus nonepidural) was 0.63 (95% confidence interval 0.25, 1.56). There were also no differences between the two groups on numeric rating scores or level of interference with activities. This prospective follow-up study demonstrated no association between epidural anesthesia for labor and delivery and chronic back pain 1 yr after delivery. ⋯ We evaluated the presence of low back pain 1 yr after delivery in two groups of women-those who chose epidural analgesia for labor and those who did not. There was no increased risk of back pain in women who had used epidural analgesia. This finding is consistent with those of other North American studies.
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Anesthesia and analgesia · Nov 1997
Clinical TrialAcute normovolemic hemodilution can replace preoperative autologous blood donation as a standard of care for autologous blood procurement in radical prostatectomy.
Predonation of autologous blood (PAD) is a standard of care for patients undergoing radical prostatectomy, but recent studies have shown that PAD is not cost-effective. Acute normovolemic hemodilution (ANH) is an alternative autologous blood procurement technique that is much less costly than PAD. We compared the efficacy and costs of ANH alone to ANH combined with PAD. Two hundred-fifty patients who predonated fewer than 3 units of autologous blood before radical prostatectomy underwent ANH to a target hematocrit of 28%. Perioperative hematocrit levels, transfusion outcomes and costs, and postoperative outcomes were compared for patients who predonated 0, 1, or 2 units of blood before surgery. A computer model was used to estimate the savings in red blood cells (RBC) associated with each autologous intervention. ANH alone resulted in a 21% allogeneic transfusion rate and contributed a mean net savings of 112 mL RBC in blood conservation (equivalent to 0.6 unit of blood). The addition of 1 or 2 units of PAD reduced allogeneic exposure rates to 6% or 0%, respectively. Overall, patients who predonated blood had a mean net loss of 198 mL of RBC (equivalent to 1 blood unit), due to both an absence in compensatory erythropoiesis and to the wastage of 60% of the blood units donated. Patients who underwent ANH alone had a 60% reduction in mean total transfusion costs ($103 +/- $102) compared with patients who predeposited 2 units of autologous blood in addition to ANH ($269 +/- $11, P < 0.05). We conclude that ANH can replace PAD as an autologous blood option because it is less costly and equally effective. A combination of ANH and PAD can further decrease allogeneic blood exposure, but it increases transfusion costs and wastage. ⋯ A patient's own blood can be obtained for use in surgery by predonation or acute normovolemic hemodilution on the day of surgery. Both blood collection techniques decrease the need for blood bank transfusions, but acute normovolemic hemodilution is less expensive and more convenient for patients.
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Comparative Study Clinical TrialA comparative efficacy study of hyperbaric 5% lidocaine and 1.5% lidocaine for spinal anesthesia.
We compared the clinical efficacy of 1.5% lidocaine in dextrose 7.5% in water, which is currently available as a commercial preparation but approved for use only in obstetrical patients, with the traditional 5% lidocaine in dextrose 7.5% in water for spinal anesthesia in patients undergoing lower abdominal procedures. Fifty-one male patients scheduled to undergo inguinal herniorrhaphy were randomly divided into two groups based on the spinal anesthetic received: Group I received 1.5% lidocaine in dextrose 7.5% in water, and Group II received 5% lidocaine in dextrose 7.5% in water. After intrathecal injection of the anesthetic, each patient was evaluated for the speed of onset, the time to recovery, and the quality of the surgical anesthesia and motor block that ensued by an anesthesiologist blinded to the technique. With the exception of the patients in Group I, who achieved a higher dermatome level of sensory analgesia, we were unable to demonstrate any significant clinical differences between the two lidocaine solutions. Our results indicate that lidocaine 1.5% in dextrose 7.5% in water is clinically indistinguishable from the 5% solution as a spinal anesthetic for lower abdominal surgery. ⋯ In this study, two concentrations of lidocaine are compared as spinal anesthetics in 51 male patients undergoing inguinal hernia repair. Patients were assessed for the onset, quality, and duration of the spinal block. The study results indicate that 1.5% lidocaine is as effective as the 5% solution as a spinal anesthetic for patients undergoing inguinal hernia repair.