Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1998
Randomized Controlled Trial Clinical TrialThe effects of maternal position during induction of combined spinal-epidural anesthesia for cesarean delivery.
Combined spinal-epidural anesthesia (CSE) is a popular technique for cesarean delivery. Regional blocks in obstetrics are often performed with the parturient in the sitting position because the midline may be recognized more easily than in the lateral decubitus position. When conventional spinal anesthesia is performed in the sitting position, the patient is placed supine immediately after drug injection. In contrast, when CSE is performed with the woman sitting, there is a delay in assuming the supine position because of epidural catheter placement, which may affect the incidence of hypotension. Healthy women, at term of pregnancy, about to undergo an elective cesarean section under CSE, were randomly assigned to the sitting or lateral recumbent position for initiation of the block. All parturients were given 1000 mL of lactated Ringer's solution in the 15 min preceding induction and an additional 300-500 mL while the actual block was being performed. On completion of the CSE, they were turned to the supine position with left uterine displacement. A second anesthesiologist, blinded to the woman's position during CSE, evaluated the sensory level of anesthesia, maternal heart rate, blood pressure, oxygen saturation, need for ephedrine, and occurrence of nausea and vomiting. Results are expressed as mean +/- SD. Twelve women were studied in the sitting group and 10 were studied in the lateral recumbent group. The severity and duration of hypotension were greater in those parturients who had CSE induced in the sitting (47%+/-7% and 6+/-3 min, respectively) compared with the lateral recumbent position (32%+/-14% and 3+/-2 min, respectively). Women in the sitting group also required twice as much ephedrine (38+/-18 mg) to correct hypotension compared with the other group (17+/-12 mg). In conclusion, the severity and duration of hypotension were greater when CSE was induced in the sitting compared with the lateral decubitus position. ⋯ We studied the induction of combined spinal-epidural anesthesia (CSE) in the sitting versus lateral recumbent positions in healthy women undergoing a scheduled cesarean delivery. The severity and duration of hypotension were greater when CSE was induced in the sitting position. Thus, the position used for induction of CSE should be among the factors considered when there is greater maternal or fetal risk from hypotension.
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Anesthesia and analgesia · Sep 1998
Randomized Controlled Trial Clinical TrialOral antihistamines reduce the side effects from rapid vancomycin infusion.
Rapid infusion of vancomycin causes histamine-mediated side effects, hypotension, and rash, known as "red man syndrome." In this prospective, randomized, double-blind, placebo-controlled study, we examined the ability of oral antihistamines to attenuate three clinical end points: rash, hypotension, and vancomycin discontinuation, and we compared these findings with those of a similar study using IV antihistamines. Patients (ASA physical status I-III) who required vancomycin prophylaxis for elective arthroplasty received either oral antihistamines (diphenhydramine < or = 1 mg/kg and cimetidine < or = 4 mg/kg, n = 20) or placebo (n = 10) 1 h before rapid vancomycin infusion (1 g over 10 min). The vancomycin infusion was discontinued if the mean arterial blood pressure decreased by > or = 20% or if itching was intolerable for the patient. Clinically significant hypotension developed in no treated patients, compared with five (50%) patients in the placebo group (P = 0.001). Rapid infusion was stopped for one treated patient (5%) and for five (50%) patients in the placebo group (P = 0.004). Incidence (P = 0.011) and severity of rash (P = 0.015) were also reduced in treated patients. Peak histamine levels were increased but were similar for patients in both groups (mean +/- SD, 1.9+/-2.5 vs 1.6+/-2.4 ng/mL; P = 0.75). Oral antihistamines were as effective as IV antihistamines. In conclusion, oral H1 and H2 antihistamine pretreatment is a practical, safe, and inexpensive option to attenuate histamine-mediated side effects associated with rapid vancomycin infusion. ⋯ Clinicians often must administer vancomycin faster than the 1-h recommended time, which can cause "red man syndrome" (rash, itching, hypotension). Our randomized, double-blind, placebo-controlled study showed that oral H1 and H2 antihistamine pretreatment significantly reduced the histamine-related side effects of rapid vancomycin infusion.
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Anesthesia and analgesia · Sep 1998
Randomized Controlled Trial Clinical TrialIntrathecal, but not intravenous, clonidine reduces experimental thermal or capsaicin-induced pain and hyperalgesia in normal volunteers.
Clonidine is approved for intraspinal administration in the treatment of neuropathic cancer pain. Some studies have suggested an analgesic effect after systemic clonidine administration. The purpose of this study was to compare the analgesic effects of intrathecal and IV clonidine with acute noxious stimulation and with hyperalgesia from intradermal capsaicin injection in volunteers. Sixteen healthy volunteers received intradermal injections of capsaicin (100 microg) before and after the IV or intrathecal injection of clonidine 50 or 150 microg in a randomized, double-blind manner. Pain and areas of mechanical hyperalgesia and allodynia were determined at specified intervals. In addition, pain to noxious heat stimulation was determined. The capsaicin injection produced pain, followed by hyperalgesia and allodynia. The intrathecal, but not IV, injection of 150 microg of clonidine reduced capsaicin-induced pain and area of hyperalgesia. Intrathecal clonidine (150 microg) reduced pain to heat stimulation, whereas IV clonidine did not. The groups did not differ in hemodynamic or sedative effects from clonidine. These data support the value of intraspinal administration of clonidine for the treatment of acute pain and of pain states associated with hyperalgesia. Similarly, they suggest that analgesia from the systemic administration of this alpha2-adrenergic agonist, if any, is weak in doses that produce sedation and reduce blood pressure. ⋯ To the extent that the experimental pain conditions used in this study reflect those in patients with acute and chronic pain, these data support the spinal rather than IV injection of clonidine for analgesia.