effect of dexmedetomidine on electrophysiological properties of normal conduction system and accessory pathways in Wolff-Parkinson-White syndrome during tanscatheter cryoablation

The effects of dexmedetomidine sedation upon the electrophysiologic [EP] properties of normal atrioventricular [A-V] and accessory pathway [AP] conduction were studied in twenty five patients with Wolff-Parkinson-White [WPW] syndrome during accessory pathway cryoablation in cardiac catheterization laboratories [CCL]. The presence of an AP was confirmed by baseline EP studies. Sedation was induced in 25 patients using dexmedetomidine [Imcg/kg] over 10 minutes and maintained with dexmedetomidine infusion [0.2 to 0.7 mcg/kg/hr]. A baseline EP study was performed which consisted of effective refractory period [ERP] and shortest cycle length [SCC] measurement during antegrade conduction in the normal A-V pathway and AP, as well as during retrograde conduction in the AP. Comparison with baseline EP studies indicated that the administration of sedation had no effect upon conduction or ERP in either patlway. Haemodynamic, blood gases showed no significant changes throughout the ablation procedure with no development of dysrrhythmia. We conclude that dexmedetomidine sedation is suitable for patients undergoing ablative procedures for accessory pathways in cardiac catheterization laboratories [CCL]

Comparison of colloid versus crystalloid preload for prevention of hypotension during spinal anesthesia for elective cesarean section in women with positive supine stress test

If parturient prone to develop caval compression in the supine position were identified before delivery; this might be a method of predicting hypotension during cesarean section under spinal anesthesia. Colloid preloading is thought to be superior to crystalloid in reducing the risk for spinal anesthetic induced hypotension. It is postulated that parturients preoperalively susceptible to the supine position would benefit the most from colloid preloading. The aim of this study is to compare colloid versus crystalloid preload for prevenilon of hypotension during spinal anesthesia for elective cesarean section in women with positive supine stress test [SST]. Forty healthy women, with term singleton normal pregnandes presenling for elective cesarean section under spinal anesthesia were included in the study. All patients were positivefir supine stress test [SST], they were divided into 2 equal groups [20 palients each], crystalloid preload group [group I] and colloid preload group [group II]. IViaternal hypotension, nausea, vomiting or dizziness and ephedrine requirements were recorded during the study. Induction-to-uterotomy interval, uterotomy-to-delivery interval and inlraoperative blood loss, were also recorded. Moreover, Apgar score and umbilical artery add-base status at delivery were measured. Our results showed that in patients received crystalloid preload [group I] the frequendes of occurrence of decreased systolic blood pressure below 100 mmHg or 20% from baseline, occurrence of vomiting, nausea or dizziness were 14[70%], 7[35%], 9[45%], and 7[35%], respectively, while, in palients received colloid preload [group II] were 6[30%], 1[5%], 2[10%], and 1[5%], respectively. So, patients received crystalloid preload showed a higher frequency of hypotension, vomiting, nausea and dizziness compared to colloid group [P<0.05], and also a greater need for ephedrine, mean[+SD] was 21[11.4] in group I compared to 7.25.3]mg in group II[P<0.05]. Pregnant women with a positive preoperative supine stress test constitute a subset at increased risk for clinically significant hypotension during cesarean delivery under spinal anesthesia. These women seem more likely to benefit from prophylaclic colloid solution preload

Effects of sevoflurane and isoflurane on coagulation system a comparative study

Several studies of the effects of inhalational anesthetic agents on platelet function have been reported since Ueda demonstrated in 1971 that clinical concentrations of halothane inhibited ADP-induced platelet aggregation. Sevoflurane in particular has recently been the subject of several investigations; however, the results remain contradictory. Platelets play an important role in hemostasis during and after surgery. Among multiple factors, interactions of drugs used in anesthesia with platelet function have been implicated to aggravate the risk of perioperative bleeding. In this study, the aim was to assess the effects of sevoflurane and isoflurane on the coagulation system. Patients were randomly divided into two groups [30 patients each]: isoflurane group [group I] and sevoflurane group [group S] according to the inhalational anesthetic used for maintenance of anesthesia. Blood samples were withdrawn before induction, 1 hour after induction and 1 hour postoperatively to measure red blood cells count, hemoglobin level, platelets count, bleeding time, prothrombin time and activity, activated partial thromboplastin time, pH, body temperature and platelet aggregation tests. The results of this study showed that red blood cells count, hemoglobin level, blood pH values and vital signs measurements were insignificantly changed during the predetermined times of measurements. Sevoflurane had a significant inhibitory effect on intraoperative platelet aggregation. Also, it had a residual suppressive effect 1 hour postoperatively, whereas it had no significant effect on other coagulation parameters including platelet count, bleeding time, prothrombin time and activity and activated partial thromboplastin time. As regards isoflurane, it had no significant effect neither on platelet aggregation nor other coagulation parameters during the intraoperative and postoperative periods. The conclusion of this study is that sevoflurane has a significant inhibitory effect on intraoperative platelet aggregation, whereas isoflurane has no effect. There is also a residual suppressive effect 1 hour postoperatively with sevoflurane. Therefore, in patients at increased risk of intraoperative and postoperative bleeding, isoflurane may be preferred as an inhalational agent for maintenance of general anesthesia.