Anesthesia and analgesia
-
Anesthesia and analgesia · Jul 1998
Comparative Study Clinical TrialComparison of plasma lidocaine concentrations after injection of a fixed small volume in the stellate ganglion, the lumbar epidural space, or a single intercostal nerve.
We measured the plasma lidocaine concentrations after stellate ganglion block (SGB) and compared them with those after intercostal nerve block (ICNB) and epidural block (EB) using identical doses of lidocaine. Thirty patients undergoing SGB (n = 10), ICNB (n = 10), or EB (n = 10) in our pain clinic participated in this study. Six milliliters of 1% lidocaine was used for all nerve blocks. SGB was performed at the C6 transverse process, ICNB was performed on a single intercostal nerve, and epidural lidocaine was injected through the lumbar epidural catheter. After drug administration, venous blood samples were taken from an indwelling catheter in the arm every minute for the first 10 min and 15, 20, 30, 45, and 60 min thereafter. Plasma lidocaine concentrations were measured by using an enzyme immunoassay method. The SGB group showed significantly higher peak plasma lidocaine concentrations than other groups (SGB 1.65 +/- 0.21 microgram/mL, ICNB 0.89 +/- 0.12 microgram/mL, EB 0.91 +/- 0.19 microgram/mL; P < 0.01). The SGB group reached peak levels significantly faster than the other groups (SGB 3.4 +/- 1.0 min, ICNB 7.9 +/- 1.5 min, EB 6.9 +/- 0.7 min; P < 0.01). We conclude that the plasma lidocaine concentrations after SGB were higher than those after ICNB and EB when using small, equal doses of lidocaine. The high and rapid peak plasma lidocaine concentrations after SGB are probably related to the high vascularity of the injection site. ⋯ Higher plasma concentrations of local anesthetics are reportedly obtained after multiple intercostal nerves blocks compared with those after other types of nerve blocks. Our results, however, showed that the peak plasma concentrations after stellate ganglion block were higher and faster than those after a single intercostal nerve block.
-
Anesthesia and analgesia · Jul 1998
Tramadol reduces the sweating, vasoconstriction, and shivering thresholds.
The analgesic tramadol inhibits the neuronal reuptake of norepinephrine and 5-hydroxytryptamine, facilitates 5-hydroxytryptamine release, and activates mu-opioid receptors. Each of these actions is likely to influence thermoregulatory control. We therefore tested the hypothesis that tramadol inhibits thermoregulatory control. Eight volunteers were evaluated on four study days, on which they received no drugs, tramadol 125 mg, tramadol 250 mg, and tramadol 250 mg with naloxone, respectively. Skin and core temperatures were gradually increased until sweating was observed and then decreased until vasoconstriction and shivering were detected. The core temperature triggering each response defined its threshold. Tramadol decreased the sweating threshold by -1.03 +/- 0.67 degrees C microgram-1.mL (r2 = 0.90 +/- 0.12). Tramadol also decreased the vasoconstriction threshold by -3.0 +/- 4.0 degrees C microgram-1.mL (r2 = 0.94 +/- 0.98) and the shivering threshold by -4.2 +/- 4.0 degrees C microgram-1.mL(r2 = 0.98 +/- 0.98). The sweating to vasoconstriction interthreshold range nearly doubled from 0.3 +/- 0.4 degree C to 0.7 +/- 0.6 degree C during the administration of large-dose tramadol (P = 0.04). The addition of naloxone only partially reversed the thermoregulatory effects of tramadol. The thermoregulatory effects of tramadol thus most resemble those of midazolam, another drug that slightly decreases the thresholds triggering all three major autonomic thermoregulatory defenses. In this respect, both drugs reduce the "setpoint" rather than produce a generalized impairment of thermoregulatory control. Nonetheless, tramadol nearly doubled the interthreshold range at a concentration near 200 ng/mL. This indicates that tramadol slightly decreases the precision of thermoregulatory control in addition to reducing the setpoint. ⋯ The authors evaluated the effects of the analgesic tramadol on the three major thermoregulatory responses: sweating, vasoconstriction, and shivering. Tramadol had only slight thermoregulatory effects. Its use is thus unlikely to provoke hypothermia or to facilitate fever.
-
Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialPeripheral nerve blocks improve analgesia after total knee replacement surgery.
Total knee replacement (TKR) produces severe postoperative pain. Peripheral nerve blocks can be used as analgesic adjuncts for TKR, but the efficacy of femoral nerve blocks alone is controversial. The sciatic nerve innervates posterior regions of the knee; thus, performance of both sciatic and femoral nerve blocks may be necessary to improve analgesia after TKR. We performed this study to determine whether peripheral nerve blocks improve analgesia after TKR. In a randomized, double-blind fashion, 36 patients undergoing TKR received either femoral, sciatic-femoral, or sham nerve blocks after a standardized spinal anesthetic. Further postoperative analgesia was provided by patient-controlled i.v. morphine and ketorolac. Pain at rest and with physical therapy, morphine use, nausea, pruritus, sedation, and patient satisfaction were assessed. Patients receiving peripheral nerve blocks reported better analgesia at rest for at least 8 h after transfer to the hospital ward (P < 0.05). Morphine use was decreased by approximately 50% in the peripheral nerve block groups until the second postoperative day (P < 0.02). Side effect profiles and patient satisfaction were similar between groups. We conclude that femoral nerve blocks improve analgesia and decrease morphine use after TKR. The addition of a sciatic nerve block to the femoral nerve block did not further improve analgesic efficacy. ⋯ Performance of femoral nerve blocks improves analgesia and decreases the need for morphine after total knee replacement surgery. The addition of a sciatic nerve block to the femoral nerve block does not provide additional benefits.
-
Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialClonidine added to the anesthetic solution enhances analgesia and improves oxygenation after intercostal nerve block for thoracotomy.
We evaluated the effect of adding clonidine to bupivacaine on postoperative pain control and oxygenation after intercostal nerve blockade (ICB) for thoracotomy, and attempted to distinguish a systemic from a local effect of clonidine. ICB with 2 mg/kg 0.5% bupivacaine was performed in 36 patients undergoing thoracotomy. Patients were randomized to one of three groups: 1) a control group that received bupivacaine with saline for ICB and an IM injection of saline, 2) an IM group that received bupivacaine with saline for ICB and an IM injection of 2 micrograms/kg clonidine, and 3) a block group that received bupivacaine with 2 micrograms/kg clonidine for ICB and an IM injection of saline. Blood gases, visual analog scale (VAS) scores, and analgesic demand were determined hourly for 8 h after arrival in the postoperative care unit (PCU). Patients in the block group had significantly lower VAS scores, higher arterial oxygen tension, and lower analgesic demand for the first 4 h in the PCU, compared with the two other groups. No difference was noted thereafter. We conclude that the addition of clonidine to bupivacaine for ICB leads to a short-term effect enhancing postoperative pain control and improving arterial oxygenation, probably mediated by a direct effect on the nerves. ⋯ Severe pain after thoracotomy can lead to impaired ventilation. We studied the effect of adding clonidine to bupivacaine for intercostal nerve blockade after thoracotomy. Clonidine administered directly on the nerves enhanced analgesia and improved oxygenation for a short time compared with systemic administration or control.
-
Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Comparative Study Clinical TrialPreemptive caudal bupivacaine and morphine for postoperative analgesia in children.
We designed this double-blind study to evaluate the efficacy of preemptive epidural bupivacaine and small-dose morphine for postoperative analgesia in children after herniorraphy. Sixty children, ASA physical status I or II, who were undergoing elective hernia repair under general anesthesia were randomly allocated into two groups. Group I (preemptive group) received 0.66 mL/kg 0.25% bupivacaine with morphine 0.02 mg/kg caudally after the induction of anesthesia but 15 min before surgery. Group II (postincisional group) received the same drug mixture after surgery. Pain was assessed using an objective pain scale (OPS). Time to first postoperative analgesics (TFA), the number of supplementary analgesic used, and the amount of morphine consumed over the ensuing 24-h period were noted. The OPS score was significantly less in Group I at 0.5, 4, and 8 h (P < 0.05) than in Group II after surgery. The median OPS score recorded over 24 h was 0 for Group I and 2 for Group II, which was significantly different (P < 0.05). The TFA in Group I (12.55 +/- 3.06 h) was significantly (P < 0.05) prolonged compared with Group II (10.62 +/- 3.18 h). The total postoperative morphine consumption in Group I (2.24 +/- 1.4 mg) was significantly (P < 0.05) less than that in Group II (3.34 +/- 2.29 mg). Nevertheless, the incidence of nausea and vomiting was not significantly different between the groups. In this study, we demonstrated that preemptive epidural bupivacaine and small-dose morphine administration is superior to the same mixture given at the conclusion of surgery for pain relief. ⋯ This study was performed on two groups of 30 children undergoing hernia repair. Group I received a bupivacaine-morphine mixture caudally before surgery, and Group II received the same drugs caudally at the completion of surgery. Postoperative assessment demonstrated longer and better pain relief in Group I.