Anesthesia and analgesia
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Anesthesia and analgesia · Feb 1999
Randomized Controlled Trial Comparative Study Clinical TrialAssessing neuromuscular block at the larynx: the effect of change in resting cuff pressure and a comparison with video imaging in anesthetized humans.
Neuromuscular block (NMB) at the larynx has been assessed by measuring the cuff pressure (CP) in an endotracheal tube (ETT) placed between the vocal cords. In this study, we evaluated the decrease in resting cuff pressure (RCP) after the administration of rocuronium and the effect of this decrease on the assessment of NMB, and we compared CP measurement with an alternative technique, video imaging (VI). In 20 patients, NMB was determined at the hand by mechanomyography and at the larynx initially by CP and subsequently by VI, recording images using a fiberoptic bronchoscope via a laryngeal mask. Train-of-four stimuli were applied at both sites. After baseline measurements, the ETT was replaced, and rocuronium was infused to achieve a steady-state 50% (n = 10) or 75% (n = 10) block at the hand. CP measurements were recorded before and after restoration of RCP to prerocuronium pressure, followed by further VI measurements. The mean RCP decreased from 21 +/- 4 to 12 +/- 5 mm Hg after rocuronium. At 50% block at the hand, the CP estimate of block at the larynx with reduced RCP was 62% +/- 18%, and that after restoring RCP was 29% +/- 13%; VI estimated 27% +/- 14% block. At 75% block at the hand, CP and VI estimated 52% +/- 11% and 46% +/- 9% block, respectively (RCP maintained). We conclude that RCP decreases after the administration of rocuronium, that restoring RCP significantly alters CP estimates of NMB, and that VI is in agreement with CP measurement if RCP is maintained at prerelaxant values. ⋯ In this study, we show that a muscle relaxant-induced decrease in resting tension at the larynx may confound the assessment of neuromuscular block by cuff pressure measurement. The preliminary data suggest that video imaging may provide a suitable alternative to cuff pressure measurement to assess neuromuscular block at the larynx.
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Anesthesia and analgesia · Feb 1999
Randomized Controlled Trial Comparative Study Clinical TrialAnesthesia for intranasal surgery: a comparison between tracheal intubation and the flexible reinforced laryngeal mask airway.
The purpose of the study was to assess the suitability and safety of the flexible reinforced laryngeal mask airway (FRLMA) for intranasal surgery (INS) anesthesia. A secondary objective was to compare the incidence of complications of removal of the FRLMA with tracheal extubation in awake and anesthetized patients. One hundred fourteen ASA physical status I and II patients requiring INS were randomly assigned into three groups: Group I = FRLMA, Group II = endotracheal tube (ET) extubated awake, and Group II = ET extubated deeply anesthetized. In Group I, the incidence of coughing and oxyhemoglobin desaturation at removal was significantly reduced compared with that in Groups II and III (P < 0.05). There were no episodes of postremoval laryngospasm in Group I; in Group III, the incidence was 19% (P < 0.05), whereas in Group II, it was 6% (not significantly different). The number of patients with oxyhemoglobin desaturation < or = 92% on admission to the postanesthesia care unit was 0% in Group I, 26% in Group II (P < 0.05), and 16% in Group III (not significantly different). At bronchoscopy, the incidence of blood visible in the airway was low and similar among the three groups (3%, 6%, and 3%, respectively). There were no significant differences in the incidence of airway complications between Groups II and III. ⋯ We compared airway management for intranasal surgery anesthesia using a new device, the flexible reinforced laryngeal mask airway, with the current standard of tracheal intubation. The study demonstrates that the flexible reinforced laryngeal mask airway can provide a safe, protected airway with a smoother emergence from anesthesia than tracheal intubation.
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Anesthesia and analgesia · Feb 1999
Randomized Controlled Trial Comparative Study Clinical TrialAssessment of the level of sensory block after subarachnoid anesthesia using a pressure palpator.
In a cross-over study, we compared two methods of assessing the level of sensory block during subarachnoid anesthesia: the traditional pinprick sensation or a novel pressure palpator exerting a pressure of 650 g. Fifty patients scheduled for transurethral surgery under subarachnoid anesthesia were randomly assigned to be tested for spread of sensory block. In Group 1, the pressure palpator was followed by pinprick; in Group 2, the reverse sequence was used. Evaluation was performed 15 and 25 min after the subarachnoid injection of 2 mL of 5% lidocaine hyperbaric solution. In Group 1, the level of sensory block assessed with the pressure palpator was 1.7 +/- 3.2 cm (0.5 +/- 1.2 dermatomes) higher than that with the pinprick at 15 min, and 2.2 +/- 3.4 cm (0.6 +/- 1.0 dermatomes) higher than that with the pinprick 25 min after the block. In Group 2, the difference was accentuated. The level of sensory block assessed by pinprick 15 min after subarachnoid lidocaine was 5.7 +/- 4.8 cm (1.2 +/- 0.9 dermatomes) lower than the level with the pressure palpator, and 4.2 +/- 3.3 cm (0.9 +/- 0.6 dermatomes) lower than that with the pressure palpator at 25 min. In all instances, the pressure palpator gave a significantly higher assessment than the pinprick. We conclude that the pressure palpator, when preceded by the pinprick test, is associated with an increased threshold. This method may be useful in assessing the sensory block produced by subarachnoid anesthesia. ⋯ A novel pressure palpator that maintains the integrity of the epidermis was used to assess the level of sensory block after subarachnoid anesthesia and was compared with the standard method of the pinprick sensation. This method assessed the block consistently higher than the pinprick method, but it may have advantages as a noninvasive sensory test.
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Anesthesia and analgesia · Feb 1999
Randomized Controlled Trial Comparative Study Clinical TrialCombination of intrathecal sufentanil 10 mug plus bupivacaine 2.5 mg for labor analgesia: is half the dose enough?
This controlled, double-blinded, prospective trial of 42 parturients in early labor was conducted to determine whether halving the total amount of intrathecal (i.t.) sufentanil and bupivacaine reduced the incidence of systemic hypotension while providing adequate analgesia with minimal lower limb motor block. Combined spinal-epidural analgesia (CSE) was instituted; Group A (n = 21) received a total of 10 microg of sulfentanil plus 2.5 mg of bupivacaine, whereas Group B (n = 21) received half that dose. Compared with Group B, Group A had a higher incidence of hypotension (nine parturients in Group A, two in Group B; P < 0.05), a greater degree of motor block (P < 0.05), and a higher incidence of sedation (nine parturients in Group A were sedated, one in Group B; P < 0.01). Group B had higher pain scores for the first 5 min (P < 0.05) and a lower level of sensory blockade (median of T7 in Group B compared with T4 in Group A; P < 0.01). We conclude that halving the total amount of i.t. 10 microg of sufentanil plus 2.5 mg of bupivacaine is a suitable option for CSE in labor because it reduces the incidence of some side effects, such as hypotension and maternal sedation, without compromising overall high maternal satisfaction. ⋯ We showed that adequate labor pain relief could be provided by halving the recommended dose of 10 microg of intrathecal sufentanil plus 2.5 mg of bupivacaine. The larger dose, however, produced faster pain relief, which lasted longer than the reduced dose. The mother and baby were not adversely affected with either dose.
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Anesthesia and analgesia · Feb 1999
Comparative Study Clinical Trial Controlled Clinical TrialDetermination of an effective dose of intrathecal morphine for pain relief after cesarean delivery.
Very small doses of intrathecal (i.t.) morphine (25-200 microg) have been used in an effort to provide effective postoperative pain relief while minimizing side effects after cesarean delivery. We performed a double-blinded study in 40 patients presenting for elective cesarean delivery in which i.t. morphine was administered along with oral hydrocodone/acetaminophen and other medications commonly administered after cesarean delivery. We administered i.t. morphine by up-down sequential allocation of doses. For the purposes of this study, adequate postoperative analgesia was defined as comfort not requiring i.v. morphine for 12 h after spinal anesthesia with bupivacaine, fentanyl, and morphine. In addition, a time and cost comparison was performed for study patients receiving intrathecal morphine compared with a historical group of patients receiving patient-controlled analgesia with i.v. morphine. We were unable to determine with meaningful precision a dose of i.t. morphine to provide analgesia in this context. However, very small doses of i.t. morphine combined with oral hydrocodone/acetaminophen and other medications commonly prescribed after cesarean delivery provided postoperative pain relief with no more time commitment than patient-controlled analgesia (148 +/- 61 vs 150 +/- 57 min) and with significantly less acquisition cost ($15.13 +/- $4.40 vs $34.64 +/- $15.55). ⋯ When used along with oral analgesics, very small doses of spinal morphine provide adequate pain relief after cesarean delivery. Spinal anesthetics, oral analgesics, and other medications commonly prescribed to treat side effects after cesarean delivery contribute significantly to this analgesia. When small doses of spinal morphine are used in this setting, they provide adequate analgesia and patient satisfaction that is time- and cost-effective.