tailieunhanh - The Anaesthesia Science Viva Book - part 3

● antecubital, hoặc hố cubital, là một hình tam giác trầm cảm intermuscular trên trước bề mặt của khớp khuỷu tay. ● Các cơ sở của tam giác được hình thành bởi các đường nối trung gian và bên epicondyles của xương cánh tay các. | CHAPTER 2 the oblique vein on the posterior surface of the left atrium the anterior cardiac vein which lies with the right coronary artery in the anterior atrio-ventricular groove and which drains directly into the right atrium. Direction the viva may take You may be asked about the physiology of coronary perfusion. At rest about 250 ml min 1 or 5 of the cardiac output is supplied to the myocardium through the coronary arteries. This can increase by up to five times during vigorous exercise. Flow is governed by the driving pressure. In the presence of a fixed coronary stenosis this pressure gradient is crucial. In the absence of a stenotic lesion the main variable that determines flow is the calibre of the blood vessels. Vasodilatation occurs mainly in response to the presence of local metabolites such as hydrogen ions adenosine potassium phosphate carbon dioxide and prostaglandins. Autonomic control of vascular tone is present but is a negligible influence in comparison. Myocardial tissue has a high oxygen extraction ratio 80 which limits its capacity for anaerobic metabolism. Increased oxygen demand therefore has to be met by an increase in coronary perfusion. During systole the sub-endocardial pressure in the left ventricle exceeds that in the outer part of the myocardium and so in the main arterial flow occurs through the arteries only in diastole. There is however some flow to the outer areas of the left ventricle throughout the cardiac cycle. In the right side of the heart which is a lower pressure system coronary perfusion persists throughout systole and diastole. At an average heart rate of 72 beats per minute about s will be spent in systole and in diastole. High heart rates can compromise ventricular perfusion as well as ventricular filling. Further direction the viva could take You may be asked about the factors that determine the balance between myocardial oxygen supply and demand. Supply Coronary blood flow as discussed above . Oxygen content .