Background. Comparative studies of ephedrine and phenylephrine in prevention of hypotension after... more Background. Comparative studies of ephedrine and phenylephrine in prevention of hypotension after spinal anaesthesia for Caesarean section have lacked a consensus on dose equivalence. The aim of this study was to determine the minimum vasopressor dose for each of these drugs to calculate the dose ratio for clinical equivalence in the prevention of hypotension. Methods. Patients with a normal singleton pregnancy beyond 36 weeks gestation undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups. The first patient in Group A received 50 mg of ephedrine in saline 0.9% w/v, 500 ml, at 999 ml h À1 , the maximum rate possible on the pump and the first patient in Group B received 500 mg of phenylephrine in saline 0.9% w/v, 500 ml, at the same rate. The initial dose for dilution was an arbitrary choice. The dose of vasopressor in the saline bag for every subsequent patient was established by the efficacy of the dose in preventing hypotension in the previous patient according to the technique of up-down sequential allocation. Minimum vasopressor dose for each drug was determined according to the Dixon-Massey formula. Results. The minimum vasopressor dose in saline 500 ml was 532.9 mg (95% CI 506.0-559.8) for phenylephrine and 43.3 mg (95% CI 39.2-47.3) for ephedrine. The concentration needed for equivalence at an infusion rate of 999 ml h À1 was 1.07 mg ml À1 for phenylephrine and 86.66 mg ml À1 for ephedrine. Mean (SD) dose used for phenylephrine was 496.45 (78.3) mg and for ephedrine 39.64 (6.33) mg. Conclusion. This study demonstrates a potency ratio of 81.2 (95% CI 73.0-89.7) for equivalence between phenylephrine and ephedrine in prevention of hypotension after spinal anaesthesia for Caesarean section.
Background. Comparative studies of ephedrine and phenylephrine in prevention of hypotension after... more Background. Comparative studies of ephedrine and phenylephrine in prevention of hypotension after spinal anaesthesia for Caesarean section have lacked a consensus on dose equivalence. The aim of this study was to determine the minimum vasopressor dose for each of these drugs to calculate the dose ratio for clinical equivalence in the prevention of hypotension. Methods. Patients with a normal singleton pregnancy beyond 36 weeks gestation undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups. The first patient in Group A received 50 mg of ephedrine in saline 0.9% w/v, 500 ml, at 999 ml h À1 , the maximum rate possible on the pump and the first patient in Group B received 500 mg of phenylephrine in saline 0.9% w/v, 500 ml, at the same rate. The initial dose for dilution was an arbitrary choice. The dose of vasopressor in the saline bag for every subsequent patient was established by the efficacy of the dose in preventing hypotension in the previous patient according to the technique of up-down sequential allocation. Minimum vasopressor dose for each drug was determined according to the Dixon-Massey formula. Results. The minimum vasopressor dose in saline 500 ml was 532.9 mg (95% CI 506.0-559.8) for phenylephrine and 43.3 mg (95% CI 39.2-47.3) for ephedrine. The concentration needed for equivalence at an infusion rate of 999 ml h À1 was 1.07 mg ml À1 for phenylephrine and 86.66 mg ml À1 for ephedrine. Mean (SD) dose used for phenylephrine was 496.45 (78.3) mg and for ephedrine 39.64 (6.33) mg. Conclusion. This study demonstrates a potency ratio of 81.2 (95% CI 73.0-89.7) for equivalence between phenylephrine and ephedrine in prevention of hypotension after spinal anaesthesia for Caesarean section.
Background: Use of Kirschner wires (K-wires) is common in pediatric elbow fracture treatment. We ... more Background: Use of Kirschner wires (K-wires) is common in pediatric elbow fracture treatment. We investigate whether anxiety levels at removal of wires may be reduced using oral midazolam. Methods: This was a prospective randomized controlled trial with 2 groups, with midazolam and with placebo. Results: Forty-two children with an average age of 7.1 years (range, 3.6-12.3 y) had complete documentation for analysis. The change in anxiety scores was not significantly different between the 2 groups. Forty-five percent of children in the midazolam group had reduced anxiety levels compared with 18% of children given placebo, but this difference was not significant (P = 0.102). The anxiety scores before and after wire removal in the midazolam group were not significantly different from the placebo group scores. Conclusions: We do not recommend the routine administration of midazolam (0.2 mg/kg) to all children requiring K-wire removal in the outpatient department. Level of Evidence: I.
Facial and hand muscles are used frequently for monitoring neuromuscular blockade. Therefore, we ... more Facial and hand muscles are used frequently for monitoring neuromuscular blockade. Therefore, we compared changes in electrically evoked muscle potential magnitude in upper facial and hypothenar muscles after fixed doses of neuromuscular blockers (succinylcholine, 750 p~g/kg; pancuronium, 70 Ixg/kg; vecuronium, 50 p~g/kg; and atracurium, 300 p~g/kg). Face-hand comparisons were made in both anesthetized (nitrous oxide/narcotic, n = 51) and comatose (closed-head injuries, n = 5) patients. In 24 anesthetized patients, complete blockade of the hypothenar muscles prevented quantitative comparison. In the remaining 27 patients, the relaxant effect (as determined by the percentage change from prerelaxant baseline muscle potentials) was significantly smaller (P < 0.0001) in the upper facial muscles (65-+ 24% versus 92 + 8%, mean-+ SD). All four evoked muscle responses to train-of-four stimulation were detectable in upper facial muscles of the 19 patients receiving nondepolarizing neuromuscular blocking drugs; this pattern was seen in hand muscles of only 7 patients (P < 0.001). The neuromuscular blockade in both the hand (49-+ 54%) and the upper facial area (68-+ 28%, P > 0.05) of comatose patients was smaller and more variable than that seen during anesthesia. These results illustrate the value of quantitative monitoring of neuromuscular function, especially during highly variable and unpredictable drug-induced blockade in the comatose state. We conclude that during narcotic-based anesthesia the upper facial and hand musdes are differentially sensitive to commonly used neuromuscular blockers.
Background. Comparative studies of ephedrine and phenylephrine in prevention of hypotension after... more Background. Comparative studies of ephedrine and phenylephrine in prevention of hypotension after spinal anaesthesia for Caesarean section have lacked a consensus on dose equivalence. The aim of this study was to determine the minimum vasopressor dose for each of these drugs to calculate the dose ratio for clinical equivalence in the prevention of hypotension. Methods. Patients with a normal singleton pregnancy beyond 36 weeks gestation undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups. The first patient in Group A received 50 mg of ephedrine in saline 0.9% w/v, 500 ml, at 999 ml h À1 , the maximum rate possible on the pump and the first patient in Group B received 500 mg of phenylephrine in saline 0.9% w/v, 500 ml, at the same rate. The initial dose for dilution was an arbitrary choice. The dose of vasopressor in the saline bag for every subsequent patient was established by the efficacy of the dose in preventing hypotension in the previous patient according to the technique of up-down sequential allocation. Minimum vasopressor dose for each drug was determined according to the Dixon-Massey formula. Results. The minimum vasopressor dose in saline 500 ml was 532.9 mg (95% CI 506.0-559.8) for phenylephrine and 43.3 mg (95% CI 39.2-47.3) for ephedrine. The concentration needed for equivalence at an infusion rate of 999 ml h À1 was 1.07 mg ml À1 for phenylephrine and 86.66 mg ml À1 for ephedrine. Mean (SD) dose used for phenylephrine was 496.45 (78.3) mg and for ephedrine 39.64 (6.33) mg. Conclusion. This study demonstrates a potency ratio of 81.2 (95% CI 73.0-89.7) for equivalence between phenylephrine and ephedrine in prevention of hypotension after spinal anaesthesia for Caesarean section.
Background. Comparative studies of ephedrine and phenylephrine in prevention of hypotension after... more Background. Comparative studies of ephedrine and phenylephrine in prevention of hypotension after spinal anaesthesia for Caesarean section have lacked a consensus on dose equivalence. The aim of this study was to determine the minimum vasopressor dose for each of these drugs to calculate the dose ratio for clinical equivalence in the prevention of hypotension. Methods. Patients with a normal singleton pregnancy beyond 36 weeks gestation undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups. The first patient in Group A received 50 mg of ephedrine in saline 0.9% w/v, 500 ml, at 999 ml h À1 , the maximum rate possible on the pump and the first patient in Group B received 500 mg of phenylephrine in saline 0.9% w/v, 500 ml, at the same rate. The initial dose for dilution was an arbitrary choice. The dose of vasopressor in the saline bag for every subsequent patient was established by the efficacy of the dose in preventing hypotension in the previous patient according to the technique of up-down sequential allocation. Minimum vasopressor dose for each drug was determined according to the Dixon-Massey formula. Results. The minimum vasopressor dose in saline 500 ml was 532.9 mg (95% CI 506.0-559.8) for phenylephrine and 43.3 mg (95% CI 39.2-47.3) for ephedrine. The concentration needed for equivalence at an infusion rate of 999 ml h À1 was 1.07 mg ml À1 for phenylephrine and 86.66 mg ml À1 for ephedrine. Mean (SD) dose used for phenylephrine was 496.45 (78.3) mg and for ephedrine 39.64 (6.33) mg. Conclusion. This study demonstrates a potency ratio of 81.2 (95% CI 73.0-89.7) for equivalence between phenylephrine and ephedrine in prevention of hypotension after spinal anaesthesia for Caesarean section.
Background: Use of Kirschner wires (K-wires) is common in pediatric elbow fracture treatment. We ... more Background: Use of Kirschner wires (K-wires) is common in pediatric elbow fracture treatment. We investigate whether anxiety levels at removal of wires may be reduced using oral midazolam. Methods: This was a prospective randomized controlled trial with 2 groups, with midazolam and with placebo. Results: Forty-two children with an average age of 7.1 years (range, 3.6-12.3 y) had complete documentation for analysis. The change in anxiety scores was not significantly different between the 2 groups. Forty-five percent of children in the midazolam group had reduced anxiety levels compared with 18% of children given placebo, but this difference was not significant (P = 0.102). The anxiety scores before and after wire removal in the midazolam group were not significantly different from the placebo group scores. Conclusions: We do not recommend the routine administration of midazolam (0.2 mg/kg) to all children requiring K-wire removal in the outpatient department. Level of Evidence: I.
Facial and hand muscles are used frequently for monitoring neuromuscular blockade. Therefore, we ... more Facial and hand muscles are used frequently for monitoring neuromuscular blockade. Therefore, we compared changes in electrically evoked muscle potential magnitude in upper facial and hypothenar muscles after fixed doses of neuromuscular blockers (succinylcholine, 750 p~g/kg; pancuronium, 70 Ixg/kg; vecuronium, 50 p~g/kg; and atracurium, 300 p~g/kg). Face-hand comparisons were made in both anesthetized (nitrous oxide/narcotic, n = 51) and comatose (closed-head injuries, n = 5) patients. In 24 anesthetized patients, complete blockade of the hypothenar muscles prevented quantitative comparison. In the remaining 27 patients, the relaxant effect (as determined by the percentage change from prerelaxant baseline muscle potentials) was significantly smaller (P < 0.0001) in the upper facial muscles (65-+ 24% versus 92 + 8%, mean-+ SD). All four evoked muscle responses to train-of-four stimulation were detectable in upper facial muscles of the 19 patients receiving nondepolarizing neuromuscular blocking drugs; this pattern was seen in hand muscles of only 7 patients (P < 0.001). The neuromuscular blockade in both the hand (49-+ 54%) and the upper facial area (68-+ 28%, P > 0.05) of comatose patients was smaller and more variable than that seen during anesthesia. These results illustrate the value of quantitative monitoring of neuromuscular function, especially during highly variable and unpredictable drug-induced blockade in the comatose state. We conclude that during narcotic-based anesthesia the upper facial and hand musdes are differentially sensitive to commonly used neuromuscular blockers.
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