British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Effect of intravenous magnesium on pain and secondary hyperalgesia associated with the heat/capsaicin sensitization model in healthy volunteers.
We investigated the effects of i.v. magnesium on secondary hyperalgesia following heat/capsaicin stimulation in human volunteers. Twenty-five volunteers were included in this double blind, randomized, crossover study. ⋯ In contrast, painfulness of thermal stimulation was increased in normal skin. These results suggest that i.v. magnesium has no important analgesic effects in clinically relevant doses.
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Randomized Controlled Trial Comparative Study Clinical Trial
Spinal anaesthesia for Caesarean section with bupivacaine 5 mg ml(-1) in glucose 8 or 80 mg ml(-1).
The standard spinal preparation of bupivacaine contains a high concentration of glucose (80 mg ml(-1)). However, the addition of only a small amount of glucose (8 mg ml(-1)) to plain solutions of bupivacaine results in a solution which, although no more than marginally hyperbaric, produces a more predictable block when used for spinal anaesthesia in non-pregnant patients. ⋯ Therefore, a double-blind, randomized, controlled study was carried out to compare intrathecal bupivacaine (glucose 8 mg ml(-1)) with bupivacaine (glucose 80 mg ml(-1)) in 40 pregnant patients at term. Although there was no difference between groups in onset of sensory block, dose of ephedrine or patient satisfaction, patients receiving bupivacaine (5 mg ml(-1)) with glucose (8 mg ml(-1)) had persistently higher sensory blocks between 60 and 120 min after intrathecal injection, suggesting that the spread of spinal solutions in the pregnant patient at term is not dependent on density.
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Comparative Study
Midazolam versus propofol for reducing contractility of fatigued canine diaphragm.
The effects of midazolam and propofol on the contractility of fatigued canine diaphragm were examined. Diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20 Hz applied for 30 min. After fatigue had been induced, group I (n=10) received no study drug, group II (n=10) was given a propofol infusion (0.1 mg kg(-1) loading dose plus 1.5 mg kg(-1) h(-1) maintenance dose) and group III (n=10) was given a midazolam infusion (0.1 mg kg(-1) loading dose plus 0.1 mg kg(-1) h(-1) maintenance dose). ⋯ Compared with group I, Pdi at 20 Hz stimulation was lower than fatigued values (P<0.05) during administration of the study drug in groups II and III. The decrease in Pdi was greater in group III than in group II (P<0.05). In conclusion, midazolam compared with propofol is associated with an inhibitory effect on contractility in the fatigued canine diaphragm.
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Reflex cardiovascular depression with vasodilation and bradycardia has been variously termed vasovagal syncope, the Bezold-Jarisch reflex and neurocardiogenic syncope. The circulatory response changes from the normal maintenance of arterial pressure, to parasympathetic activation and sympathetic inhibition, causing hypotension. This change is triggered by reduced cardiac venous return as well as through affective mechanisms such as pain or fear. ⋯ Treatment includes the restoration of venous return and correction of absolute blood volume deficits. Ephedrine is the most logical choice of single drug to correct the changes because of its combined action on the heart and peripheral blood vessels. Epinephrine must be used early in established cardiac arrest, especially after high regional anaesthesia.