[Show abstract][Hide abstract] ABSTRACT: Background: It is well known that patients undergoing shoulder surgery in the Beach Chair Position (BCP) have a potential risk for cerebral ischemia. Using Near-Infrared Spectroscopy (NIRS), this study aimed to test whether cerebral oxygenation in these patients was impaired by brachial plexus block accompanied with general anesthesia. Methods: Ultrasound-guided interscalene brachial plexus block was performed in 26 patients undergoing elective arthroscopic shoulder surgery under general anesthesia. In all subjects, cerebral oxygenation during anesthesia was evaluated by measuring the Tissue Oxygenation Index (TOI) with NIRS. Results: No differences were seen in TOI values between Pre-BCP and Post-BCP periods in both block and non-block sides, despite a decrease in mean blood pressure (P<0.05, repeated measures one-way ANOVA by the Bonferroni post hoc test). Additionally, no differences were seen in TOI values between block and non-block sides at any time point. Conclusion: Changing from the supine position to the BCP did not appear to impair cerebral oxygenation, regardless of brachial plexus block, in patients undergoing shoulder arthroscopy under general anesthesia.
Journal of Anesthesia & Clinical Research 01/2013; 4(11). DOI:10.4172/2155-6148.1000367 · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Purpose: Several different anti-hypertensive regimens have been introduced for the prevention of systemic hyperdynamic responses after electrically induced seizures. In the present study, the effects of anti-hypertensive medications on cerebral circulation were studied. Methods: Systemic blood pressure was controlled by several anti-hypertensive medications, nicardipine, prostaglandin E1, alprenolol and nitroglycerin, in 30 patients (150 electroconvulsive therapy trials). Changes in cerebral blood flow velocity were measured by transcranial Doppler sonography of the right middle cerebral artery from the start of anesthesia to 10 min after the electrical shock. Results: Administration of a Ca2+ antagonist, nicardipine, or prostaglandin E1 did not alter the augmented cerebral blood flow velocity after the seizure. However, a β-adrenergic blocking agent, alprenolol (P < 0.05) or nitroglycerin (P < 0.01) partially inhibited the increase in cerebral blood flow velocity. Maximal blood flow velocity was 133% larger than the pre-anesthesia value in the control group, 109% in the nicardipine group, 113% in the prostaglandin E1 group, 72% in the alprenolol group, and 45% in the nitroglycerin group, respectively. The increase in cerebral blood flow velocity after electrically induced seizure was independent of systemic blood pressure. Internal jugular venous saturation (SjO2) was increased, and difference in arterial and venous concentrations of lactate was not altered in all groups. Conclusions: Cerebral hemodynamics is altered by ECT, even when systemic hemodynamics are stabilized by antihypertensive medication. Although the effects of antihypertensive medicine on cerebral hemodynamics are variable, systemic blood pressure control by these agents does not induce cerebral ischemia after ECT.
Canadian Journal of Anaesthesia 04/2012; 47(8):767-774. DOI:10.1007/BF03019479 · 2.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Antidepressants are often used for the treatment of neuropathic pain. Clinical studies suggest that the efficacy of serotonin (5-HT) and noradrenaline (NA) reuptake inhibitors (SNRIs) for neuropathic pain is greater than that of selective 5-HT reuptake inhibitors (SSRIs). In the present study, we determined the efficacy and mechanisms involved in the antihyperalgesic effects of milnacipran, an SNRI, compared with paroxetine, an SSRI, and maprotiline, a selective NA reuptake inhibitor, using a rat model of neuropathic pain. Male Sprague-Dawley rats underwent spinal nerve ligation (SNL), and the withdrawal threshold to paw pressure was measured. Intraperitoneal injection of milnacipran (3-30mg/kg) produced a dose-dependent antihyperalgesic effect. The effect was reversed by intrathecal injection of the α(2)-adrenoceptor antagonist idazoxan (30μg), but not by various 5-HT receptor antagonists. Paroxetine produced an antihyperalgesic effect only at the highest dose tested (10mg/kg). This effect was reversed by intrathecal injection of both idazoxan and ondansetron (30μg), a 5-HT3 receptor antagonist. Maprotiline produced an antihyperalgesic effect (10 and 30mg/kg), and the effect was reversed by intrathecal idazoxan. In microdialysis studies, NA and 5-HT concentrations in the spinal dorsal horn were increased after injection of either milnacipran or paroxetine, and only NA was increased after maprotiline. Furthermore, the NA content in the spinal cord of SNL rats was greater than that in normal animals. These findings suggest that an increase in NA in the spinal cord plays an important role in the antihyperalgesic effects of not only NA reuptake inhibitors but also SSRIs.