Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2000
Randomized Controlled Trial Clinical TrialThe effect of remifentanil on the bispectral index change and hemodynamic responses after orotracheal intubation.
In order to examine whether changes in the bispectral index (BIS) may be an adequate monitor for the analgesic component of anesthesia, we evaluated the effect of remifentanil on the BIS change and hemodynamic responses to laryngoscopy and tracheal intubation. Fifty ASA physical status I patients were randomly assigned, in a double-blinded fashion, to one of five groups (n = 10/group) according to the remifentanil target effect compartment site concentration (0, 2, 4, 8, or 16 ng/mL). The target-controlled infusion (TCI) of remifentanil was initiated 3 min after the TCI of propofol that was maintained at the effect-site concentration of 4 microg/mL throughout the study. After the loss of consciousness and before the administration of vecuronium 0.1 mg/kg, a tourniquet was applied to one arm and inflated above the systolic blood pressure in order to detect any gross movement within the first minute after tracheal intubation, which was performed 3 min after remifentanil TCI began. A BIS value was generated every 10 s. Arterial blood pressure and heart rate (HR) were measured every minute, noninvasively. Measures of mean arterial pressure (MAP), HR, and BIS were obtained before the induction, before the start of remifentanil TCI, before laryngoscopy, and 5 min after intubation. The relationships between remifentanil effect-site concentrations and BIS change or hemodynamic responses (changes in MAP and HR) to intubation were determined by logarithmic regression. BIS values were not affected by remifentanil before laryngoscopy. During this period, MAP and HR decreased significantly (P < 0.01) in the remifentanil 8 and 16 ng/mL groups. Changes in BIS, MAP, and HR were negatively correlated with remifentanil effect-site concentration (P < 0.0001). The number of movers in the remifentanil 0-, 2-, 4-, 8-, and 16-ng/mL groups was, respectively, 10, 9, 7, 1, and 0. Hypotensive episodes (MAP < 60 mm Hg) were noted in 1, 2, and 5 patients in the remifentanil 4-, 8-, and 16-ng/mL groups, respectively. We conclude that the addition of remifentanil to propofol affects BIS only when a painful stimulus is applied. Moreover, remifentanil attenuated or abolished increases in BIS and MAP after tracheal intubation in a comparable dose-dependent fashion. ⋯ Bispectral index change is as sensitive as hemodynamic responses after a painful stimulus for detecting deficits in the analgesic component of anesthesia. It may, therefore, be a useful monitor of the depth of anesthesia in patients who are incapable of HR and MAP responses to noxious stimuli because of medications or cardiovascular disease.
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Anesthesia and analgesia · Jan 2000
Randomized Controlled Trial Clinical TrialThree-in-one blocks with ropivacaine: evaluation of sensory onset time and quality of sensory block.
The purpose of this prospective, randomized, double-blinded study was to evaluate the sensory onset time and the quality of sensory block of ropivacaine, a new long-acting local anesthetic, compared with bupivacaine, for 3-in-1 blocks. Fifty ASA physical status I-III patients undergoing hip surgery after trauma were randomly assigned to two study groups of 25 patients each. The two study groups received a 3-in-1 block with either 20 mL of ropivacaine 0.5% or 20 mL of bupivacaine 0.5%. Blocks in both groups were performed using a nerve stimulator. The sensory onset time and the quality of sensory block was assessed by pinprick test in the central sensory region of each of the three nerves and compared with the same stimulation in the contralateral leg. We used a scale from 100% (normal sensation) to 0% (no sensory sensation). We did not find significant differences in sensory onset times between the ropivacaine group and the bupivacaine group (30+/-11 vs 32+/-10 min). The quality of sensory blocks was also comparable between the study groups (19%+/-20% vs 21%+/-15%). We conclude that the sensory onset time and quality of sensory block during 3-in-1 blocks performed with ropivacaine are comparable to those with bupivacaine. Ropivacaine is described as being less potent than bupivacaine, making this local anesthetic promising for 3-in-1 blocks because of its reportedly lower incidence of cardiovascular and central nervous system complications. ⋯ Ropivacaine 0.5% has a sensory onset time and quality of sensory block during 3-in-1 blocks similar to that of bupivacaine 0.5%. Ropivacaine is described as being less potent than bupivacaine, making it a promising local anesthetic for 3-in-1 blocks because of its reportedly lower cardiovascular and central nervous system toxicity.
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Anesthesia and analgesia · Jan 2000
Randomized Controlled Trial Clinical TrialTwo-lung and one-lung ventilation in patients with chronic obstructive pulmonary disease: the effects of position and F(IO)2.
We compared the effects of position and fraction of inspired oxygen (F(IO)2) on oxygenation during thoracic surgery in 24 consenting patients randomly assigned to receive an F(IO)2 of 0.4 (eight patients, Group 0.4), 0.6 (eight patients, Group 0.6), or 1.0 (eight patients, Group 1.0) during the periods of two-lung (TLV) and one-lung ventilation (OLV) in the supine and lateral positions. TLV and OLV were maintained while the patients were first in the supine and then in the lateral position for 15 min each. Thereafter, respiratory mechanical data were obtained, and arterial blood gas samples were drawn. Pao2 decreased during OLV compared with TLV in both the supine and lateral positions. In all three groups, Pao2 was significantly higher during OLV in the lateral than in the supine position: 101 (72-201) vs 63 (57-144) mm Hg in Group 0.4; 268 (162-311) vs 155 (114-235) mm Hg in Group 0.6; and 486 (288-563) vs 301 (216-422) mm Hg in Group 1.0, respectively (P < 0.02, Wilcoxon's signed rank test). We conclude that, compared with the supine position, gravity augments the redistribution of perfusion as a result of hypoxic pulmonary vasoconstriction, when patients are in the lateral position, which explains the higher Pao2 during OLV. ⋯ This study compares oxygenation during thoracic surgery during periods of two-lung and one-lung ventilation with patients in the supine and lateral positions when using three different fraction of inspired oxygen values. Arterial oxygen tension was decreased in all three groups during one-lung ventilation in comparison with the two-lung ventilation values, but the decrease was significantly less in the lateral, compared with the supine position.
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Anesthesia and analgesia · Jan 2000
Randomized Controlled Trial Clinical TrialThe benefits of intraoperative small-dose ketamine on postoperative pain after anterior cruciate ligament repair.
In a randomized, double-blinded study with three parallel groups, we assessed the analgesic effect of intraoperative ketamine administration in 45 ASA physical status I or II patients undergoing elective arthroscopic anterior ligament repair under general anesthesia. The patients received either IV ketamine 0.15 mg/kg after the induction of anesthesia and before surgical incision and normal saline at the end of surgery (PRE group); normal saline after the induction of anesthesia and before surgical incision and IV ketamine at the end of surgery (POST group); or normal saline at the beginning and the end of surgery (CONT group). Anesthesia was performed with propofol (2 mg/kg for induction, 60-200 microg x kg(-1) x min(-1) for maintenance), sufentanil (0.2 microg/kg 10 min after surgical incision, followed by an infusion of 0.25 microg x kg(-1) x h(-1) stopped 30 min before skinclosure), vecuronium (0.1 mg/kg), and 60% N2O in O2 via a laryngeal mask airway. Postoperative analgesia was initially provided with IV morphine in the postanesthesia care unit, then with IV patient-controlled analgesia started before discharge from the postanesthesia care unit. Pain scores, morphine consumption, side effects, and degree of knee flexion were recorded over 48 h and during the first and second physiotherapy periods, performed on Days 1 and 2. Patients in the ketamine groups required significantly less morphine than those in the CONT group over 48 h postoperatively (CONT group 67.7+/-38.3 mg versus PRE group 34.3+/-23.2 mg and POST group 29.5+/-21.5 mg; P < 0.01). Better first knee flexion (CONT group 35+/-10 degrees versus PRE group 46+/-12 degrees and POST group 47+/-13 degrees; P < 0.05) and lower morphine consumption (CONT group 3.8+/-1.7 mg versus PRE group 1.2+/-0.4 mg and POST group 1.4+/-0.4 mg; P < 0.05) were noted at first knee mobilization. No differences were seen between the PRE and POST groups, except for an increase in morphine demand in the PRE versus the POST group (P < 0.05) in the second hour postoperatively. ⋯ We found that intraoperative small-dose ketamine reduced postoperative morphine requirements and improved mobilization 24 h after arthroscopic anterior ligament repair. No differences were observed in the timing of administration. Intraoperative small-dose ketamine may therefore be a useful adjuvant to perioperative analgesic management.