Anesthesia and analgesia
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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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Anesthesia and analgesia · Jan 2004
Randomized Controlled Trial Clinical TrialThe effects of prolonged ambulation on labor with epidural analgesia.
Ambulation during labor is becoming more popular, although its impact on the progress of labor and on pain intensity remains unclear. We wondered whether prolonged ambulation with epidural analgesia had a possible effect on duration of labor and pain. In this prospective, randomized trial, 61 parturients with uncomplicated term pregnancies were allocated to be recumbent (n = 31) or to ambulate (n = 30). Epidural analgesia was provided with intermittent administrations of 0.08% bupivacaine-epinephrine plus 1 microg/mL of sufentanil. Of the 30 women assigned to the ambulatory group, 25 actually walked. Their ambulating time was 64 +/- 34 min (mean +/- SD), i.e., 29% +/- 16% of the first stage. There were no differences between the two groups in the length of labor and in pain visual analog scale scores. However, the ambulatory group received smaller doses of bupivacaine (6.4 +/- 2.2 mg/h versus 8.4 +/- 3.6 mg/h; P = 0.01) and of oxytocin (6.0 +/- 3.7 mUI/min versus 10.2 +/- 8.8 mUI/min; P < 0.05). A greater ability to void was also found in the ambulatory group (P < 0.01). Although the duration of labor and pain relief was unchanged, these findings support that ambulation during labor may be advantageous. ⋯ This study compared the duration of labor and pain relief between parturients receiving epidural analgesia who were ambulated or were recumbent. Whereas walking had no impact on either duration of labor or pain relief, it was associated with a reduction in both bupivacaine and oxytocin requirements.
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Anesthesia and analgesia · Jan 2004
Comparative StudySpinal chloroprocaine solutions: density at 37 degrees C and pH titration.
The density and pH of a local anesthetic are important characteristics in its use as an intrathecal drug. Preservative- and antioxidant-free formulations of chloroprocaine are available and are being investigated for short-duration spinal anesthesia. In this study, we evaluated the pH and density (to 5 significant digits in g/mL, at 37.0 degrees C) of these new chloroprocaine formulations. In addition to plain 2% and 3% chloroprocaine and 2% lidocaine, mixed solutions of 2% chloroprocaine with epinephrine or with bicarbonate were evaluated. Density was also measured after water dilution and after increasing amounts of added dextrose. Chloroprocaine, 2% or 3%, is hyperbaric relative to cerebrospinal fluid (CSF) before any addition of dextrose (density 1.00123 g/mL and 1.00257 g/mL, respectively). When diluted with water, all the solutions are hypobaric relative to CSF (density <1.00028 g/mL). Plain 2% lidocaine is the only dextrose-free solution measured to be hypobaric (density 1.00004 g/mL). Bisulfite-free 2-chloroprocaine remains very acidic (pH <4.0), but the pH can be increased to more than 7.0 with a small amount of bicarbonate (0.25-0.33 mL/10 mL). The increased density of plain chloroprocaine makes it a useful hyperbaric spinal drug without the addition of dextrose. ⋯ Dextrose-free 2-chloroprocaine is hyperbaric relative to cerebrospinal fluid at 37 degrees C, and therefore can be used for spinal anesthesia without dextrose. Bisulfite-free 2-chloroprocaine remains very acidic (pH <4.0). The pH can be increased to more than 7.0 with a small amount of bicarbonate (0.25-0.33 mL/10 mL).
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Anesthesia and analgesia · Jan 2004
Clinical TrialAssessing propofol induction of anesthesia dose using bispectral index analysis.
In this study we sought to determine the propofol requirement and hemodynamic effects as guided by bispectral index (BIS) analysis during induction of anesthesia. Sixty patients were enrolled in this study. Propofol, 2 mg/kg, was given to Group I for induction. Propofol was administered for induction until loss of response to verbal commands and until BIS values were around 50 to Groups II and III. After induction, the smallest BIS value was different in Group I. Decreases in total propofol dose were 36% and 43% in Groups II and III respectively as compared with Group I. The dose of propofol assessed by BIS analysis results in an important reduction of propofol requirement without side effects. ⋯ Hypotension during induction of anesthesia with propofol is common. This study has shown that propofol requirement assessed by bispectral index analysis during anesthesia induction may decrease the dose and side effects and provide for satisfactory depth of anesthesia.
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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.