British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
A prospective, randomized comparison of preoperative and continuous balanced epidural or paravertebral bupivacaine on post-thoracotomy pain, pulmonary function and stress responses.
Both epidural and paravertebral blocks are effective in controlling post-thoracotomy pain, but comparison of preoperative and balanced techniques, measuring pulmonary function and stress responses, has not been undertaken previously. We studied 100 adult patients, premedicated with morphine and diclofenac, allocated randomly to receive thoracic epidural bupivacaine or thoracic paravertebral bupivacaine as preoperative bolus doses followed by continuous infusions. All patients also received diclofenac and patient-controlled morphine. ⋯ Areas under the plasma concentration vs time curves for cortisol and glucose were significantly lower in the paravertebral groups. Side effects, especially nausea, vomiting and hypotension, were troublesome only in the epidural group. We conclude that with these regimens, paravertebral block was superior to epidural bupivacaine.
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Randomized Controlled Trial Comparative Study Clinical Trial
Augmentation of vecuronium-induced neuromuscular block during sevoflurane anaesthesia: comparison with balanced anaesthesia using propofol or midazolam.
We have quantified the potentiating effects of 1.7% sevoflurane (n = 12) on vecuronium-induced neuromuscular block and compared the results with those obtained during balanced anaesthesia with propofol (n = 12) or midazolam (n = 12) in 36 patients. Neuromuscular function was monitored using an accelerograph and the train-of-four responses of the adductor pollicis muscle to ulnar nerve stimulation. Vecuronium 0.1 mg kg-1 was administered as an intubating dose, and maintenance doses of 0.02 mg kg-1 were administered on three occasions when T1/T0 had recovered to 25%. ⋯ Times to 25% recovery of T1/T0 (DUR25) after an intubating dose of vecuronium did not differ between groups (mean 44.2 (SD 18.7) min for sevoflurane, 38.3 (7.5) min for propofol and 35.5 (9.5) min for midazolam). DUR25 values after each maintenance dose were 29.8 (9.5) min, 30.3 (10.4) min and 31.6 (10.7) min during sevoflurane anaesthesia, and were significantly longer than values for propofol (21.7 (6.0) min, 21.5 (5.8) min and 21.9 (5.8) min) and midazolam (20.0 (5.9) min, 19.3 (7.7) min and 19.8 (8.0) min) (P < 0.05) in each case). Recovery index25-75% and interval from T1/T0 = 25% to T4/T1 = 0.7 after the final dose of vecuronium were significantly prolonged by sevoflurane (28.3 (13.2) min and 42.7 (16.4) min) compared with propofol (17.6 (6.1) min and 26.6 (9.8) min) or midazolam (16.3 (9.4) min and 26.0 (10.2) min) (P < 0.05 in each case).
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Randomized Controlled Trial Clinical Trial
A potential mechanism of propofol-induced pain on injection based on studies using nafamostat mesilate.
To elucidate the mechanism of propofol-induced pain on injection, we performed several studies using nafamostat mesilate, a kallikrein inhibitor, or lidocaine. As both pretreatment and low-dose mixing with nafamostat produced the same effects on pain reduction, we used the latter method in the following experiments. Low-dose mixing had the same effect on injection pain as mixing with lidocaine. ⋯ Injection of the lipid solvent before propofol significantly aggravated pain compared with prior injection of saline, although the lipid solvent injected twice caused no change in pain. These results suggest that the lipid solvent for propofol activates the plasma kallikrein-kinin system and produces bradykinin which modifies the injected local vein. This modification of the peripheral vein may increase the contact between the aqueous phase propofol and the free nerve endings of the vessel, resulting in aggravation of propofol-induced pain.
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Randomized Controlled Trial Clinical Trial
Re-evaluation of appropriate size of the laryngeal mask airway.
We have assessed 32 males and 31 females in a randomized, crossover study to see if there was any difference in the correct positioning of the laryngeal mask, optimal ventilation (defined as no gas leak around the mask at an airway pressure of 18 cm H2O) and cuff visibility between sizes 4 and 5 masks in males and sizes 3 and 4 in females. The position of the mask in relation to the glottis was assessed using a fibreoptic bronchoscope. ⋯ Gas leak was significantly less frequent for a larger than a smaller mask (P < 0.01 for both sexes), whereas the cuff was more often seen in the mouth with larger masks (P < 0.02 for males and P < 0.01 for females). Therefore, larger masks (size 4 in females and size 5 in males) provided a better seal than smaller sizes without worsening the relative position of the mask to the glottis; however, the larger mask came up within the mouth more often, which could interfere with tonsillectomy and could increase the risk of sore throat or lingual nerve damage.
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Randomized Controlled Trial Clinical Trial
Effects of dexmedetomidine on isoflurane requirements in healthy volunteers. 2: Auditory and somatosensory evoked responses.
The anaesthetic-sparing activity of dexmedetomidine during isoflurane anaesthesia was examined, using the end-point of lack of response to tetanic nerve stimulation. Nine subjects were given two doses of dexmedetomidine (target plasma concentrations of 0.3 ng ml-1 and 0.6 ng ml-1, respectively) and saline on separate occasions. We measured auditory (AER) and somatosensory (SER) evoked responses at end-tidal isoflurane concentrations of 0.2-1.4%. ⋯ The dose of dexmedetomidine had a significant interaction with this trend (P < 0.002). Decreasing the concentration of isoflurane at the high dose of dexmedetomidine had less impact on P15-N20 amplitude than decreasing isoflurane at the low dose or with saline. The mechanism by which dexmedetomidine spares isoflurane is discussed in the light of these evoked response changes.