Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Comparative Study Clinical TrialComparison of 9 mg of intrathecal plain and hyperbaric bupivacaine both with fentanyl for cesarean delivery.
We randomized 76 parturients to a double-blinded trial to receive spinal anesthesia with either hyperbaric or plain bupivacaine 9 mg with fentanyl 20 microg for elective cesarean delivery. A combined spinal-epidural technique was used. The onset and duration of anesthesia (absence of pinprick sensation), analgesia (absence of sharp sensation to pinprick), and absence of cold sensation and motor block were measured until recovery from the motor block. No major differences were seen in onset or duration of anesthesia between the groups. Motor block, however, vanished faster when hyperbaric bupivacaine was used (P < 0.05). The level of anesthesia (no pinprick sensation) required for painless operation was at dermatome T5. At this time, the absence of cold sensation ranged from dermatome T1 to C3. The median time for the anesthesia to reach dermatome T5 was 10 min. Cervical spread of pinprick anesthesia was noted in six patients, and five needed supplementary analgesics during surgery (not significant between the groups). Maternal satisfaction was good. Nine milligrams of either plain or hyperbaric bupivacaine with fentanyl intrathecally provided similar onset, depth, and duration of sensory anesthesia for cesarean delivery with good maternal satisfaction. Motor block developed and diminished faster with the hyperbaric solution. ⋯ Nine milligrams of either plain or hyperbaric bupivacaine with fentanyl intrathecally provided similar onset, depth, and duration of sensory anesthesia for cesarean delivery with good maternal satisfaction. Motor block developed and diminished faster with the hyperbaric solution.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Comparative Study Clinical TrialInterscalene brachial plexus analgesia after open shoulder surgery: continuous versus patient-controlled infusion.
In this prospective, randomized, double-blinded study, we assessed the efficacy of patient-controlled analgesia (PCA) for continuous interscalene analgesia after open shoulder surgery. Sixty patients were divided into three groups of 20. During a 48-h period, they received, via an interscalene catheter, a continuous infusion of 0.125% bupivacaine with sufentanil 0.1 microg/mL and clonidine 1 microg/mL at 10 mL /h in Group 1; a continuous infusion of the same solution at 5 mL/h plus PCA boluses (2.5 mL/30 min) in Group 2; and only PCA boluses (5 mL/30 min) of the same solution in Group 3. Pain scores, sensory block, supplemental analgesia, bupivacaine consumption, side effects, and satisfaction scores were recorded. At 24 and 48 h, sensory block was more frequent and pain control was significantly better in Groups 1 and 2 than in Group 3 (P < 0.001). In Group 3, larger doses of paracetamol were required. Bupivacaine consumption was significantly less in Groups 2 and 3 than in Group 1 (P < 0.001). Satisfaction was significantly higher in Groups 1 and 2 than in Group 3 (P < 0.01). Side effects were comparable in the three groups. We conclude that continuous interscalene analgesia requires a background infusion after open shoulder surgery. Because it reduces the local anesthetic consumption and allows the patients to rapidly reinforce the block shortly before physiotherapy, a basal infusion rate of 5 mL/h combined with PCA boluses (2.5 mL/ 30 min) is the recommended technique. ⋯ In this study, we demonstrated that continuous interscalene analgesia requires a background infusion to provide efficient pain relief after open shoulder surgery. A basal infusion of 5 mL/h combined with patient-controlled analgesia boluses (2.5 mL/30 min) seems to be the most appropriate technique.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Comparative Study Clinical TrialPressures exerted against the cervical vertebrae by the standard and intubating laryngeal mask airways: a randomized, controlled, cross-over study in fresh cadavers.
In this randomized, controlled, cross-over study, we measured the pressures exerted by the standard laryngeal mask airway (LMA) and the intubating laryngeal mask airway (ILM) against the cervical vertebrae during insertion, intubation, and maneuvers commonly used to facilitate intubation. We also assessed the effect of these pressures on cervical spine (C-spine) movement. Twenty cadavers (6-24 h postmortem) without cervical abnormality were initially studied. Three microchip pressure sensors were implanted into the pharyngeal surface of C2-3. The size 5 ILM and LMA were inserted in random order into each cadaver with the head-neck in the neutral position. Maximal cervical pressures (CPmax) were recorded for both devices during cuff inflation from 0-40 mL and with the intracuff pressure (ICP) at 60 cm H2O, insertion, fiberscope-guided intubation, partial withdrawal/reinsertion (ILM only), elevation/depression of the handle with 20 N of force applied (ILM only). In five additional matched cadavers, the effect of pressure on posterior displacement of C3 was assessed, and CPmax was measured during laryngoscope- and fiberscope-guided oro/nasotracheal intubation (controls). CPmax was higher for the ILM than the LMA over the inflation range (96 vs 15 cm H2O; P < 0.0001) and with the ICP at 60 cm H2O (95 vs 10 cm H2O; P < 0.0001). During cuff inflation, CPmax was generally unchanged for the ILM but was always increased for the LMA. CPmax for the LMA and ILM was similar during insertion (224 vs 273 cm H2O) but higher for the ILM during fiberscope-guided intubation (96 vs 43 cm H2O; P < 0.0001). At 60 cm H2O ICP, CPmax increased during LMA (224 cm H2O; P < 0.0001) and ILM insertion (273 cm H2O; P < 0.0001) and increased for the LMA (43 cm H2O; P < 0.0001) but was unchanged for the ILM (96 cm H2O) during fiberscope-guided intubation. For the ILM, CP-max increased during handle depression (394 cm H2O; P < 0.0001) and partial withdrawal/reinsertion (265 cm H2O; P < 0.0001) but decreased during handle elevation (6 cm H2O; P < 0.00001). CPmax for the controls was usually zero and was always less than the LMA/ ILM (P < 0.0001). The mean (range) for posterior displacement of C3 was 0.8 (0-2) mm at 100 cm H2O and 2.8 (1-5) mm at 400 cm H2O. Laryngeal mask devices exert greater pressures against the cervical vertebrae than established intubation techniques and can produce posterior displacement of the C-spine. ⋯ Laryngeal mask devices exert greater pressures against the cervical vertebrae than established intubation techniques and can produce posterior displacement of the cervical spine. We recommend that laryngeal mask devices only be used in the unstable cervical spine if difficulties are anticipated or encountered with established techniques, pending the results of studies demonstrating its relative safety.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialThe effect of midazolam premedication on mental and psychomotor recovery in geriatric patients undergoing brief surgical procedures.
To assess the effect of IV midazolam premedication on recovery of cognitive function, 90 geriatric patients (aged 65-81 yr) undergoing brief transurethral procedures were enrolled into this prospective, placebo-controlled, double-blinded study. In all cases, a standard general anesthetic was administered. Thirty minutes before operating room transfer, patients in Group 0.5 mg, Group 2 mg, and Group S received 0.5 mg of midazolam, 2 mg of midazolam, or an equal volume of saline, respectively. Before study-drug administration (baseline), at 15 min thereafter, as well as on arrival in the postanesthesia care unit (PACU), and at 60 min and 120 min, postoperatively, we administered a digit-symbol substitution test, a mini-mental test, a shape-sorter test, and a patient-generated 100-mm visual analog score (0 = minimal and 100 = maximal) for anxiety, sleepiness, and coordination. A 4-point scale was used to assess the degree of patient sedation at 7, 15, and 30 min after study-drug administration. Using a modified Aldrete scoring system, PACU discharge was determined by the PACU staff. Patient anxiety, sleepiness, and coordination scores at baseline and at 15 min after study-drug administration were similar. When compared with saline, midazolam was associated with a significantly (P < 0.05) higher incidence of "deep" sedation. In Group 2 mg, the incidence of a low preoperative Spo2 (<94%) was significantly (P < 0.05) higher when compared with Group S. Emergence, extubation, and orientation times, as well as time to follow commands were unaffected by midazolam premedication. Postoperatively, the digit-symbol substitution test, mini-mental test, and shape-sorter test were similar among the groups. However, time to PACU discharge was significantly (P = 0.03) longer in the two midazolam treatment groups (41 +/-25 min, 60 +/- 32 min, 53 +/- 39 min for Groups S, 0.5 mg, and 2 mg, respectively). Finally, patient satisfaction was unaffected by the randomization schedule. ⋯ IV premedicant midazolam 0.5 mg or 2 mg does not adversely affect mental and psychomotor recovery in geriatric patients undergoing brief surgical procedures. However, midazolam administration significantly prolonged postanesthesia care unit discharge time. Finally, during the preoperative period, midazolam increases the incidence of a Spo2 <94% in a dose-dependent manner.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialThe lateral approach to the sciatic nerve at the popliteal fossa: one or two injections?
It has not been proven whether one or multiple nerve stimulations and injections provide a higher rate of complete sensory block in both major sciatic nerve sensory distributions below the knee when a popliteal sciatic nerve block is performed using the lateral approach. This prospective, randomized, single-blinded study compared the success rate of the sciatic nerve block using this approach when one or both major components of this nerve (i.e., tibial nerve and common peroneal nerves) are stimulated in 50 patients undergoing foot or ankle surgery. In Group 1 STIM, 24 patients received a single injection of 20 mL of a mixture of 2% lidocaine and 0.5% bupivacaine with 1:200,000 epinephrine after foot inversion had been elicited. In Group 2 STIM (n = 26), 10 mL of the same solution was injected after stimulation of each sciatic nerve component. For patients with complete sensory motor block, there was no difference in onset between groups. However, Group 2 STIM showed a greater success rate compared with the Group 1 STIM (2 STIM: 88% vs 1 STIM :54%; P = 0.007). When two stimulations were used, the onset time of anesthesia in the cutaneous distribution of the common peroneal nerves was shorter than in the tibial nerve (17.5 vs 30 min; P < 0.0001). We conclude that a two-stimulation technique provides a better success rate than a single-injection technique when a popliteal sciatic nerve block is performed using the lateral approach with 20 mL of local anesthetic. ⋯ A better success rate is achieved with a double stimulation technique than with a single injection for the sciatic nerve block via the lateral approach at the popliteal fossa when 20 mL of local anesthetics is used.