Anesthesia and analgesia
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Anesthesia and analgesia · Feb 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe in vitro effects of isoflurane, sevoflurane, and propofol on platelet aggregation.
We studied the in vitro effects of sevoflurane, isoflurane, and propofol anesthesia on platelet function. Thirty patients undergoing minor surgical procedures were divided into three groups (n = 10 each). Induction of anesthesia was achieved by using 5 mg/kg thiopental i.v., and 0.1 mg/kg vecuronium i.v. was used for muscle relaxation. Anesthesia maintenance was provided by sevoflurane in the first, isoflurane in the second, and propofol infusion in the third group with 70% N2O in O2. Hemoglobin, hematocrit, thrombocyte count, prothrombin time, activated partial thromboplastin time, international normalized ratio, arterial pH, von Willebrand factor, viscosity, platelet aggregation, and bleeding time were measured 1 h pre-, intra-, and postanesthesia. There was no difference among the platelet aggregation ratios of the pre-, intra-, and postoperative periods in the isoflurane group. The aggregation ratios in the sevoflurane and propofol groups were significantly reduced at intraoperative periods compared with preoperative values. Diminished aggregation values were also found 1 h postoperatively compared with the control values in the sevoflurane and propofol groups. We conclude that, in patients with a bleeding tendency during the intra- and early postoperative period, isoflurane may be preferred as a general anesthetic. ⋯ In our study, using vacuum-operated tubes, we demonstrated that sevoflurane and propofol had a significant inhibitory effect on intraoperative and early postoperative platelet aggregation, whereas isoflurane had no effect. Therefore, isoflurane may be preferred as a general anesthetic in patients with a clinically relevant bleeding tendency.
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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.
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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
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 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.