The Yale journal of biology and medicine
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There are multiple sites at which the brachial plexus block can be induced in selecting regional anesthesia for upper extremity surgical patients. The most frequently used blocks are axillary, infraclavicular, supraclavicular, and interscalene. One must understand brachial plexus anatomy to use these blocks effectively, as well as the practical clinical differences between the blocks. ⋯ Interscalene block is especially effective for surgical procedures involving the shoulder or upper arm because the roots of the brachial plexus are most easily blocked with this technique. The final needle tip position with this block is potentially near the centroneuraxis and arteries perfusing the brain, thus careful aspiration of the needle and incremental injection are important. In summary, when an understanding of branchial plexus anatomy is combined with proper block technique and a patient- and procedure-specific balancing of risk-benefit, our patients and colleagues will be coadvocates of our branchial plexus regional blocks.
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This paper will review the basics of neurostimulation in the perioperative period. Following a brief overview of neuromuscular physiology, the mechanism of action of depolarizing and non-depolarizing relaxants will be discussed. ⋯ Clinical assessment of neuromuscular function will then be compared with both subjective and objective means of assessment of adequacy of intraoperative relaxation and postoperative reversal. The principles reviewed in this paper will then be applied in the clinical setting, and risks and benefits associated with perioperative use of muscle relaxants will be discussed.
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The relative merits of general vs regional anesthesia for patients undergoing major vascular surgery has been the subject of debate over the past decade. Previous studies of regional vs general anesthesia often were deficient in experimental design and, therefore, did not produce definitive answers. Some of these deficiencies related to non-standardized, poorly conducted, and/or described general anesthetic techniques, nonstandardized methods of postoperative analgesia in the general anesthesia groups, and variations in preoperative cardiac status in the study groups. ⋯ The reported beneficial effects have included amelioration of the neuroendocrine stress response to surgery, improvement in pulmonary function, cardiovascular stability, enhancement of lower limb blood flow, reduction in the incidence of graft thrombosis, and a reduction in the thrombic response to surgery. Skeptics still question whether recent studies have the power to determine whether regional anesthesia decreases the incidence of cardiac and pulmonary complications following major vascular surgery. Furthermore, the issue of whether the beneficial effects of regional anesthesia on the incidence of graft thrombosis and the thrombotic response to surgery relating to intraoperative or postoperative regional anesthesia/analgesia, to regional anesthesia per se, or to the systemic effects of absorbed local anesthetics remains unresolved.
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The development of ambulatory electrocardiographic recorders and analysers and the application of transesophageal echocardiography in the mid-1980's enabled investigators to quantify and describe the occurrence of silent as well as symptomatic ischemia in the perioperative period. Several technical advances which have recently occurred in ECG monitoring include the use of miniaturized digital computing equipment to store and analyze data. In addition, real time ST-segment analysis has become widely available on multicomponent monitors in both the operating room and intensive care units. ⋯ Postoperative pain, physiological and emotional stress may all combine to cause tachycardia, hypertension, increase in cardiac output, and fluid shifts which, in high risk patients, might result in subendocardial ischemia and eventual myocardial infarction. If postoperative myocardial ischemia is the cause of late postoperative myocardial infarction in patients undergoing non-cardiac surgery, then treatment of postoperative myocardial ischemia should reduce morbidity. In addition, reducing pain and stress and avoiding postoperative hypoxemia might prevent postoperative myocardial ischemia and minimize the need for extensive preoperative cardiac evaluation.
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Perioperative cardiac events continue to represent a significant cause of morbidity in patients undergoing noncardiac surgery. The evaluation of the high risk patient should begin with an assessment of the probability of coronary artery disease and exercise tolerance. Decisions to undergo further evaluation, including noninvasive testing, should be based upon the perioperative morbidity and mortality rate for the planned surgical procedure. In patients with significant coronary artery stenoses and a high probability of perioperative cardiac morbidity, coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, and preoperative optimization of hemodynamics in an intensive care unit have all been advocated as means of reducing risk.