Anesthesia and analgesia
-
Anesthesia and analgesia · Feb 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of needle bevel orientation during epidural catheter insertion in laboring parturients.
Lateral needle bevel orientation during identification of the epidural space has been recommended to reduce the risk of postdural puncture headache (PDPH). Rotation to cephalad or caudad orientation before catheter insertion is assumed necessary for analgesic success. We prospectively compared the effects of catheter insertion through lateral- and cephalad-oriented Tuohy needle bevels in laboring parturients. Anesthesiology residents were randomized to identify the epidural space with bevels oriented cephalad or lateral. Catheters were inserted without needle rotation. Outcomes compared included ease of insertion, analgesic effectiveness, and complications. We evaluated 534 catheter insertions in 500 parturients. Initial catheter insertion produced satisfactory analgesia in 80.2% of the lateral group versus 91.1% of the cephalad group (P < 0.001). Resistance preventing catheter insertion accounted for the difference. There were no differences in i.v. cannulation (5.8% vs 5.1%), dural puncture (3.8% vs 2.0%), PDPH (0.4% vs 0.7%), or asymmetric block (31% vs 27%). There was a slightly higher rate of paresthesias in the lateral group (31% vs 23%; P = 0.048). In 78% of parturients experiencing both paresthesias and asymmetric block, the side of the paresthesia and greater extent of block were the same. Analgesic effectiveness, as measured by using a visual analog scale, was not different between the groups. ⋯ Two methods of epidural catheter insertion were compared in laboring parturients. Catheter insertion with the needle orifice oriented cephalad was associated with the greatest initial success and the fewest complications.
-
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.
-
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.
-
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.
-
Anesthesia and analgesia · Feb 1999
Randomized Controlled Trial Comparative Study Clinical TrialSomatosensory evoked potential monitoring used to compare the effect of three asymmetric sternal retractors on brachial plexus function.
We compared the effect of three different asymmetric sternal retractors on brachial plexus dysfunction using intraoperative somatosensory evoked potentials (SSEPs). We studied 60 patients undergoing coronary bypass and internal mammary harvest. Assessment of brachial plexus function was performed pre- and postoperatively. Patients were assigned the use of a Pittman (MN Scientific Instruments Inc., Minneapolis, MN), Rultract (Rultract Inc., Cleveland, OH), or Delacroix-Chevalier (Delacroix-Chevalier, Paris, France) asymmetric sternal retractor for internal mammary exposure. SSEP changes from baseline during asymmetric retractor use and removal were determined, and average changes were compared among the retractor groups. Patient demographics and baseline SSEP values were similar. Fewer patients in the Delacroix-Chevalier group had decreases in SSEP amplitudes after retractor placement. Of the patients in the Rultract and Pittman groups, 45% and 25%, respectively, had amplitude decreases of >50%, compared with only 5% of the Delacroix-Chevalier patients. Three patients in both the Pittman and Rultract groups and one patient in the Delacroix-Chevalier group suffered brachial plexus symptoms postoperatively. We conclude that the Delacroix-Chevalier retractor is associated with less neurophysiologic evidence of brachial plexus dysfunction during asymmetric sternal retraction compared with either the Pittman or Rultract sternal retractors. ⋯ We used somatosensory evoked potentials to assess the effect of several different asymmetric sternal retractors on brachial plexus dysfunction and to determine which produced the least evidence of nerve damage during surgical exposure of the internal mammary artery.