View clinical trials related to Spinal Anesthesia.
Filter by:Patients undergoing lower extremity surgery with spinal anesthesia are often sedated to reduce patient discomfort due to large noises during surgery and also to reduce anxiety. Most commonly used sedatives include propofol and midazolam, but these agents are known to often cause hypotension or respiratory depression. Dexmedetomidine is a selective alpha 2 adrenergic drug, which acts as a sedative and also has analgesia effects. In contrast to propofol or midazolam, dexmedetomidine rarely causes respiratory depression, and therefore is often used in critically ill patients in the ICU and also in patients undergoing simple procedures. Hemodynamically, dexmedetomidine evokes a biphasic blood pressure response with a short hypertensive phase and subsequent hypotension. Bradycardia is also observed in many patients, which may lead to more serious outcomes when progressing to sinus pause or shock. Therefore, drugs to prevent bradycardia during dexmedetomidine infusion may help patients maintain a more stable hemodynamic state. The present study aims to compare the ability of atropine and glycopyrrolate to prevent bradycardia during dexmedetomidine infusion in patients undergoing lower extremity orthopedic surgery with spinal anesthesia.
ECG changes during caesarean section are common. Incidence of ST depression on the ECG is up to 81% in some studies. Although this may indicate inadequate oxygen supply to the heart muscle (myocardial ischaemia) many other theories have been suggested including air entering the circulation from the placental bed, high heart rate, hormone or nervous system influences and spasm of the coronary blood supply. Perioperative ST depression often reflects an imbalance between heart muscle oxygen supply and demand. At the time of delivery, high heart rate is common and there is a further increase in the amount of blood the heart has to pump every minute due to blood coming back to the circulation from the placental bed. This increases oxygen demand and most ST changes are seen at the time of delivery or within 30 minutes. The clinical significance of these changes is much debated, and apart from a few case reports do not appear to be associated with poor heart muscle function or ischaemia (lack of oxygen supply). Management of the mother's blood pressure during caesarean section has changed greatly in recent years. Intermittent boluses of ephedrine, given when blood pressure is low, have been replaced with prevention of low blood pressure and phenylephrine has become the drug of choice. Ephedrine increases heart rate and contractility of the heart muscle and is likely to increase oxygen demand. Phenylephrine reduces heart rate while maintaining blood pressure which may result in a more favorable oxygen supply demand ratio. The investigators aim to compare the incidence of ECG changes if the mother's blood pressure is maintained with phenylephrine as compared to ephedrine. To see if these ECG changes are associated with myocardial ischaemia, the investigators will perform troponin T analysis after delivery. Troponin T is a molecule released by ischaemic heart muscle.