Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2004
Randomized Controlled Trial Clinical TrialSpinal 2-chloroprocaine: the effect of added fentanyl.
Chloroprocaine is being investigated as a possible replacement for spinal lidocaine. Adding fentanyl to lidocaine increases the quality of spinal anesthesia without prolongation of block. We report the characteristics of 2-chloroprocaine (2-CP) spinal anesthesia with or without fentanyl in 8 volunteers receiving 40 mg 2-CP with saline or 20 micro g fentanyl in a double-blinded, randomized, crossover manner. Spinal anesthesia was successful for all subjects with complete block regression, ambulation, and void by 110 min. Itching occurred in all subjects receiving fentanyl, though medication was not required. No subject reported signs of transient neurological symptoms. Peak block with fentanyl averaged T5 (T3-7) and without fentanyl T9 (L1-T4) (P = 0.005). Regression to L1 was 78 +/- 7 min with fentanyl and 53 +/- 19 min without fentanyl (P = 0.02). Tourniquet was tolerated for 51 +/- 8 min with fentanyl and for 34 +/- 14 min without fentanyl (P = 0.02). Complete regression of block occurred at 104 +/- 7 min with fentanyl and by 95 +/- 9 min without fentanyl (P = 0.02). We conclude that 2-CP spinal anesthesia provides rapid onset and adequate potency, giving it a positive profile for ambulatory surgery. The addition of fentanyl lengthens regression to L1 and tourniquet tolerance while minimally lengthening block duration. ⋯ Spinal 2-chloroprocaine (40 mg) provides rapid onset and reliable blockade without signs of transient neurological symptoms, giving it a positive profile for ambulatory surgical settings. The addition of fentanyl appears to lengthen the regression to L1 dermatome and tourniquet time while minimally lengthening duration of block.
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Anesthesia and analgesia · Jan 2004
Clinical Trial Controlled Clinical TrialClonidine prolongs spinal anesthesia in newborns: a prospective dose-ranging study.
Spinal anesthesia may reduce the incidence of morbidity that follows general anesthesia in neonates and in former preterm infants. However, bupivacaine alone provides a block too short for complete surgery in up to 40% of the patients. Clonidine lengthens spinal anesthesia in adults and caudal block in children without significant side effects. We conducted a controlled, prospective, dose-ranging study of clonidine in spinal anesthesia in 75 neonates, including 50% of former preterm infants, undergoing elective inguinal herniorrhaphy. Patients were given a spinal anesthetic with either 0.5% plain isobaric bupivacaine (1 mg/kg), or bupivacaine plus 0.25, 0.5, 1, or 2 micro g/kg clonidine. Mean arterial blood pressure, heart rate, SpO(2), sensory block extension and duration were the main data recorded. Mean arterial blood pressure, heart rate, SpO(2), and block extension were similar in the five groups. Duration of spinal block increased from 67 (58-82) min in the control group up to 111 (93-125) min in the group receiving 1 micro g/kg clonidine (P < 0.003). Transient hypotension occurred more often (P < 0.05), and caffeine was given more often, when 2 micro g/kg clonidine was given. We conclude that 1 micro g/kg clonidine provides a significant improvement in spinal anesthesia duration in newborns without significant side effects. ⋯ Spinal anesthesia is suitable but often too short for complete surgery in newborns. This controlled, randomized, prospective, dose-ranging study was conducted in 75 neonates to test the hypothesis that clonidine could significantly lengthen bupivacaine spinal block. Clonidine 1 micro g/kg, added to spinal isobaric bupivacaine, doubles the duration of the block without significant deleterious hemodynamic or respiratory side effects.
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In this clinical trial we evaluated the clinical effects of levobupivacaine in spinal anesthesia in children. An open, noncomparative study was performed on 40 children, aged 1-14 yr, undergoing elective lower abdominal or lower limb surgery. A plain solution of S(-)-bupivacaine 5 mg/mL at a mean dose of 0.3 mg/kg body weight (range, 0.2-0.5 mg/kg body weight) was administered via the L3-4 or L4-5 interspace with the patient in the lateral decubitus position. After injection, the patients were placed supine. The spread and duration of sensory analgesia and the degree of motor block were recorded. Satisfactory surgical anesthesia was achieved in 39 of the 40 children. One child received supplemental anesthesia. The mean highest level of sensory block was T4 (range, T2 to L1), and the mean time to the regression of sensory block to T10 was 90 min (range, 43-185 min). A complete motor block was achieved in 36 children. These results are similar to those obtained with racemic bupivacaine in subarachnoid anesthesia in children. ⋯ This noncomparative, descriptive study showed that levobupivacaine, the S(-)-enantiomer of bupivacaine, has equivalent clinical efficacy in spinal anesthesia in children to that of racemic bupivacaine.
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Anesthesia and analgesia · Jan 2004
Clinical TrialA novel infraclavicular brachial plexus block: the lateral and sagittal technique, developed by magnetic resonance imaging studies.
A new infraclavicular brachial plexus block method has the patient supine with an adducted arm. The target is any of the three cords behind the pectoralis minor muscle. The point of needle insertion is the intersection between the clavicle and the coracoid process. The needle is advanced 0 degrees -30 degrees posterior, always strictly in the sagittal plane next to the coracoid process while abutting the antero-inferior edge of the clavicle. We tested the new method using magnetic resonance imaging (MRI) in 20 adult volunteers, without inserting a needle. Combining 2 simulated needle directions by 15 degrees posterior and 0 degrees in the images of the volunteers, at least one cord in 19 of 20 volunteers was contacted. This occurred within a needle depth of 6.5 cm. In the sagittal plane of the method the shortest depth to the pleura among all volunteers was 7.5 cm. The MRI study indicates that the new infraclavicular technique may be efficient in reaching a cord of the brachial plexus, often not demanding more than two needle directions. The risk of pneumothorax should be minimal because the needle is inserted no deeper than 6.5 cm. However, this needs to be confirmed by a clinical study. ⋯ A new infraclavicular brachial plexus block method was investigated using magnetic resonance imaging without inserting needles in the volunteers. The study suggests two needle directions for performance of the block and that the risk of lung injury should be minimal. Expectations need to be confirmed by a clinical study.
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Anesthesia and analgesia · Jan 2004
Orthostatic hypotension occurs frequently in the first hour after anesthesia.
Symptoms of orthostatic intolerance are common after general anesthesia and are associated with an increased risk of postoperative morbidity. The contribution of orthostatic hypotension (OH) has not been well defined. We conducted a head-up tilt test on patients after general anesthesia for minor surgery to assess the incidence of and risk factors for OH after general anesthesia. One-hundred-four patients were enrolled and were prospectively divided into four groups: older female, older male, young female, and young male. The incidence of OH was 76.0%, 72.0%, 45.5%, and 62.5% respectively and was associated with increasing age (P < 0.05) and posttest dizziness (P < 0.05). Body mass index, preoperative blood pressure, ASA class, anesthetic duration, IV fluid administration, and use of analgesics and antiemetics in the postanesthetic care unit were not different in subjects who demonstrated OH compared with those with a normotensive response. Subjects with OH after general anesthesia did not increase their heart rate and diastolic blood pressure with a head-up tilt which may have been caused by persistent effects of anesthetics on reflex cardiovascular control and/or bedrest-induced dysregulation of reflex cardiovascular control. We conclude that OH is common after general anesthesia for minor surgery and may be the major cause of postoperative orthostatic intolerance. ⋯ Orthostatic hypotension, a failure to maintain blood pressure on assuming an upright posture, is common after general anesthesia for minor surgery and may be the major cause of postoperative orthostatic intolerance.