The effects of transcranial electrical stimulation on anaesthesia and analgesia in rats.

In this study, we determined the effects of transcranial electrical stimulation (TCES) on the anaesthetic requirements of thiopental and the analgesic requirements of remifentanil, in rats. The experiments were performed on 120 albino male Wistar rats, which were randomly allocated to four groups (n=30). (Thiopental, Thiopental+TCES, Thiopental+Remifentanil, and Thiopental+Remifentanil+TCES). Animals were anaesthetized with thiopental, and 15 min later, remifentanil was injected to rats in the Remifentanil groups. TCES was started in the stimulated groups 20 min after thiopental administration. Rats were stimulated 5 times for this experiment. The times for recovery, herein called Cognition Recovery Time and Motion Recovery Time were measured. Cognition Recovery and Motion Recovery Times were not affected by the stimulation. Analgesia was assessed using the wet tail-flick latency (TFL). In the Thiopental group, the analgesia level returned to control values on the 35th min. In the Thiopental+Remifentanil group, the analgesia level returned to control values on the 50th min. In the Thiopental+ TCES group, the analgesia level reached the peak value on the 65th min. In the Thiopental+Remifentanil+TCES group, the analgesia level reached the peak value on the 35th min and analgesia remained high during the 90 min after cessation of the stimulation. The analgesic potency for the Thiopental+Remifentanil+TCES group was increased by 30-40% when compared with the prior TFL values, 160% when compared with the control group, and 50-75% when compared with Thiopental+TCES group on the 35th min (P<0.001). In conclusion, TCES markedly decreases the anaesthetic and analgesic requirements for thiopental and remifentanil in rats.

Comparison of postoperative analgesic effects of preemptively used epidural ketamine and neostigmine.

STUDY OBJECTIVE: To compare the analgesic and side effects of preemptively used epidural ketamine +bupivacaine, neostigmine +bupivacaine, and bupivacaine alone on postoperative analgesia after major abdominal surgery. DESIGN: Randomized, controlled study. SETTING: Inpatient anesthesia at the department of surgery of a metropolitan hospital. PATIENTS: 30 ASA physical status I, II, and III patients scheduled for abdominal surgery. INTERVENTIONS: Group K received 1 mL (50 mg) ketamine and 5 mL (25 mg) bupivacaine epidurally, Group N received 1 mL (0.5 mg) neostigmine and 5 mL (25 mg) bupivacaine epidurally, and Group B received 1 mL saline and 5 mL (25 mg) bupivacaine epidurally 30 minutes before operation. All patients underwent anesthesia induction with thiopental and vecuronium; anesthesia was maintained with isoflorane and vecuronium. For postoperative analgesia, all patients received epidural morphine for 48 hours postoperatively. MEASUREMENTS AND MAIN RESULTS: Standard monitoring included: 48 hours of analgesic requirement, visual analog scale (VAS), mean arterial pressure (MAP), and heart rate (HR) in the 1st, 2nd, 6th, 12th, 24th, and 48th hours. Data were analyzed using Kruskall-Wallis and Mann Whitney U tests, with a p < 0.05 considered statistically significant. No significant differences were observed regarding MAP and HR among the groups during the study period. In Group N, VAS was significantly lower than Group K and Group B. The total opioid consumption in Group N was significantly lower than in Groups K and B in the first 48 hours after the operation. CONCLUSIONS: Preemptive neostigmine can be a good choice for postoperative analgesia.

Ambulatory inguinal herniorrhaphy: paravertebral block versus spinal anesthesia.

AIM: Inguinal herniorrhaphy (IH) is a common surgical procedure that can be successfully performed by using general, regional or local anesthesia and is usually performed in an outpatient setting. In this study, recovery profile, incidence of adverse effects, postoperative pain scores and patient satisfaction between paravertebral block (PVB) and spinal anesthesia (SA) for fast track ambulatory IH were compared. METHODS: Sixty patients were randomly assigned to receive either PVB or unilateral SA under standardized protocols (PVB at T9-L1 levels with 5 mL of 0.5 % levobupivacaine for each, unilateral SA at L2-L3 level with 8 mg 0.5% hyperbaric levobupivacaine). All patients were sedated with propofol, 10-70 mg.kg.min. Data on anesthesia, surgery and PACU times, hemodynamic changes, home readiness, pain, and incidence of adverse effects were recorded. RESULTS: One block failed in the PVB group. Anesthesia-related time and onset time were longer in the PVB group, but phase 1 PACU time, time to home-readiness with and without voiding and actual discharge time were significantly shorter in the PVB group. Although the fast-tracking rate was higher in the PVB group, this difference was not significant. The mean propofol dose was higher in the PVB group (52.03+/-19.32 [35-73] mg x kg x min-1) than in the SA group (44.0+/-18.8 [33-70] mg x kg x min-1) (P=0.002). VAS scores at 4, 6 and 12 hours were significantly lower in the PVB group, both at rest and during movement. VAS scores at 30, 60, 120, 180 min and at 18, 24 and 48 hours were comparable in the two groups. Duration of sensory block, onset time of discomfort, time to first analgesic, and time to first rescue analgesic were longer in the PVB group. CONCLUSIONS: In ambulatory IH, PVB provided shorter home readiness time, long lasting postoperative analgesia and improved quality of recovery, and could be a good alternative to SA.

Can remifentanil be a better choice than propofol for colonoscopy during monitored anesthesia care?

BACKGROUND AND OBJECTIVE: This prospective, randomized trial was designed to test the hypothesis that continuous infusion of low-dose remifentanil can provide effective analgesia, sedation, amnesia, patient comfort and stable recovery profile without respiratory depression when compared with propofol infusion during colonoscopy. METHODS: One hundred patients were randomly assigned to receive either remifentanil (group R, 0.5 microg/kg followed by 0.05 microg/kg/min, n = 50) or propofol (group P, 0.5 mg/kg followed by 50 microg/kg/min, n = 50). Supplemental doses of remifentanil 12.5 microg in group R and propofol 10 mg in group P were given to treat complaints of moderate to severe pain and discomfort. Hemodynamic and respiratory data, pain, discomfort and sedation scores, patient and gastroenterologist satisfaction and recovery profiles were recorded. RESULTS: The duration of colonoscopy was longer in group P. The mean arterial pressure, heart rate and end-tidal CO2 remained stable during the procedure and were comparable between the groups. After bolus injection of the study drugs, the respiratory rate and oxygen saturation values were lower in group R than in group P. Only one patient in group R required airway support. Pain and discomfort scores were better in group R than in group P. Sedation levels were higher in group P than in group R. Group P needed more supplemental doses than group R. The time to reach an Aldrete score of nine or more was shorter in group R, but discharge times were similar in the two groups. Amnesia was better in group P. Nausea and vomiting were more frequent in group R during the recovery phase. CONCLUSION: Low-dose remifentanil infusion with intermittent bolus injections can provide adequate sedation, amnesia and better analgesia than propofol infusion during colonoscopy. However, remifentanil-induced nausea and vomiting may be a problem during the recovery phase.

Effects of remifentanil and alfentanil on seizure duration, stimulus amplitudes and recovery parameters during ECT.

BACKGROUND AND OBJECTIVE: Propofol may decrease seizure duration in electroconvulsive therapy. Although not proven, prolonged seizures may be more efficacious. The goal of this study was to evaluate and compare effects of alfentanil and remifentanil on seizure duration, recovery parameters and degree of stimulus amplitude in patients undergoing electroconvulsive therapy. METHODS: Twenty-four ASA I-II patients enrolled in this prospective, randomized trial, each receiving a total of seven electroconvulsive therapies. Patients were randomized to receive only Propofol, group P (0.75 mg kg-1, n=8), Propofol with alfentanil, group A (10 microg kg-1 alfentanil+0.5 mg kg-1 Propofol, n=8) and Propofol with remifentanil, group R (1 microg kg-1 remifentanil +0.5 mg kg-1 propofol, n=8) via an iv route. Supplemental doses of propofol were given as required to achieve loss of consciousness. Succinylcholine 0.5 mg kg-1 iv was given to all groups for muscular paralysis. We recorded hemodynamic parameters, cortical and motor seizure durations, and recovery parameters. RESULTS: Mean motor seizure duration was found to be significantly longer in patients receiving propofol-remifentanil anesthesia (53.3+/-13.6 s) and propofol-alfentanil anesthesia (52.2+/-0.4 s) compared with propofol anesthesia (37.6+/-9.2 s) (P=0.001). Recovery parameters and stimulus amplitudes were similar in groups A and R; significantly different from group P (P=0.001). CONCLUSIONS: Adding 10 microg kg-1 alfentanil or 1 microg kg-1 remifentanil to reduced doses of propofol provided unconsciousness and increased seizure durations. For patients who need higher stimulus amplitudes for longer seizure durations, combining low-dose propofol with alfentanil or remifentanil may be good alternative regimens for ECT.

Propofol and intralipid interact with reactive oxygen species: a chemiluminescence study.

We have studied the ability of propofol and Intralipid to inhibit reactive oxygen species generated either by stimulated human leucocytes or cell-free systems using luminol chemiluminescence. Human leucocytes were stimulated by a chemotactic peptide, FMLP 1 mumol litre-1, or by a phorbol ester, PMA (protein kinase C activator) 0.1 mumol litre-1. In cell-free experiments, superoxide-hydrogen peroxide, hypochlorous acid or hydroxyl radical-induced chemiluminescence responses were initiated by xanthine 0.1 mmol litre-1 with xanthine oxidase 10 mu. ml-1, NaOCl 70 mumol litre-1 and FeSO4 3 mumol litre-1, respectively. Propofol with Intralipid, and to a lesser degree Intralipid alone, produced a concentration-dependent reduction in chemiluminescence from stimulated leucocytes. Similar attenuations were also observed using propofol with Intralipid on xanthine with xanthine oxidase-, HOCl- and ferrous iron-induced chemiluminescence. However, Intralipid produced a reduction only at high concentrations. Intralipid produced marked decreases in ferrous iron-induced chemiluminescence. This study suggests that propofol had a direct scavenging activity against HOCl, superoxide-hydrogen peroxide and hydroxyl radical in the concentrations used. These direct scavenging effects may contribute to the effect of propofol on human leucocyte chemiluminescence.