Arterial blood flow

Vascular grafts are tubular devices implanted throughout the body to replace blood vessels which have become obstmcted by plaque, atherosclerosis, or otherwise weakened by an aneurysm. Grafts are used most often in peripheral bypass surgery to restore arterial blood flow in the legs. 

Body temperatures are primarily sensed by temperature sensors in the hypothalamus near the center of the brain. Arterial blood flowing over and near the hypothalamus gives it information about the average thermal condition of... 

When administering a drug into a vein by a venipuncture, tiie nurse should place a tourniquet above the selected vein. It is important to tighten the tourniquet so that venous blood flow is blocked but arterial blood flow is not. The nurse should allow the veins to fill (distend) and then should pull tiie skin taut (to anchor the vein and the skin) and insert tiie needle into tiie vein, bevel up, and at a short angle to tiie skin. Blood should immediately flow into the syringe if tiie needle is properly inserted into the vein. 

The adrenergic dragp are important in the care and treatment of patients in shock. Shock is defined as a life-threatening condition of inadequate perfusion. In shock, there is an inadequate supply of arterial blood flow and oxygen delivery to the cells and tissues. The body initiates compensatory mechanisms to counteract the symptoms of shock (eg, the release of epinephrine and norepinephrine), hi some situations, the body is able to compensate and blood pressure is maintained. However, if shock is untreated and compensatory mechanisms of the body fail, irreversible shock occurs and... 

Chan K-H, Miller JD, Dearden NM, Andrews PJ, Midgley S. The effect of changes in cerebral perfusion pressure upon middle cerebral artery blood flow velocity and jugular bulb venous oxygen saturation after severe brain injury. J Neurosurg 1992 77(1) 55-61. 

Percutaneous coronary intervention A minimally invasive procedure whereby access to the coronary arteries is obtained through the femoral artery up the aorta to the coronary os. Contrast media is used to visualize the coronary artery stenosis using a coronary angiogram. A guidewire is used to cross the stenosis and a small balloon is inflated and/or stent is deployed to break up atherosclerotic plaque and restore coronary artery blood flow. The stent is left in place to prevent acute closure and restenosis of the coronary artery. Newer stents are coated with antiproliferative drugs, such as paclitaxel and sirolimus, which further reduce the risk of restenosis of the coronary artery. 

Anaesthetized studies conducted using data capture systems to record six lead ECG (I, II, III, aV, and aVf), left ventricular pressure variables, arterial blood pressure and respiratory measurement of arterial blood flow in selected vascular beds, cardiac output and arterial blood gas measurement. ECG intervals are measured from the lead II ECG and Q-T interval can be corrected for heart rate using Bazett s, Friderecia s or Van De Water s formulas. 

The V/Q term describes the imbalance between ventilation (V) and perfusion (Q) in different areas of the lung. Given that alveolar ventilation is 4.5 l.min and pulmonary arterial blood flow is 5.0 l.min 1, the overall V/Q ratio is 0.9. Both ventilation and perfusion increase from top to bottom of the lung, but perfusion by much more than ventilation. 

Kodaira K, Fujishiro K, Wada T, Male K, Satoi T, Tsukiyama E, Fukumoto T, Uchida T, Yamazaki S, Okamura T (1993) A study on cerebral nicotine receptor distribution, blood flow, oxygen consumption, and other metabolic activities-a study on the effects of smoking on carotid and cerebral artery blood flow. Yakubutsu Seishin Kodo 13 157-165... 

NG headaches are ascribed to distention of intracranial veins or reduction of venous tone or insufficient tone resulting from enhanced arterial blood flow (Ref 3)... 

Thus, the patient with a toxic TCA concentration (see the case at the start of the Metabolism section) developed excessively high amitriptyline plasma levels due to the additive effects of diminished left ventricular function leading to decreased hepatic arterial blood flow alcohol and age-related decline in liver function and, finally. 

There are many different procedures used for pancreas transplantation, and there is no one standard protocol used in all transplant centers. The important considerations, however, are that the arterial blood flow supply to the pancreas and duodenal segment, and venous outflow from the pancreas via the portal vein should be adequate. The recipient s right common or external iliac artery is used to restore vascularization of the artery in the pancreas. The Y graft of the tissue is anastomosed end-to-side and the venous vascularization is performed either systemically or portally, but mostly it is done with systemic venous drainage. 

The direction of arterial blood flow in the nose runs anteriorly against inspiration. Blood vessels are arranged in such a manner as to provide an erectile capacity to the mucosa enabling the airway to widen and narrow. Blood flow through the autonomically controlled vasculature of the nasal tissue is of importance in the conditioning of inspired air. 

The occlusion pressure in the following equation is the surface pressure applied by the tourniquet required to occlude the arterial blood flow. Belt tension required for occlusion, rBocc (pounds), is found by combining the two equations above to be ... 

Blood is delivered to the human kidney by the renal artery. Blood flows to the kidneys of the adult human at a rate of roughly 1 L/min. The adult human kidney contains approximately 1 million functional units, called nephrons, to which the blood is delivered for removal of solutes. Collected materials are excreted from the body in the urine. 

The atherosclerotic lesions develop in a complex, chronic process. The first detectable lesion is the so-called fatty streak, an aggregation of lipid-laden macrophage foam cells. The next stage of development is the formation of plaques consisting of a core of lipid and necrotic cell debris covered by a layer of connective tissue and smooth muscle cells. These plaques hinder arterial blood flow and may precipitate clinical events by plaque rupture and thrombus formation. Platelets from the thrombi, activated macrophages, and smooth muscle cells release growth factors and cytokines resulting in an inflammatory-fibroproliferative response that leads to the advanced lesions of atherosclerosis. 

A number of animal models have been developed to mimic cerebral ischemia experimentally. They can be roughly categorized into global (bilateral arterial occlusion) and focal (unilateral arterial occlusion) cerebral ischemia models. Probably the widest applied method is the middle cerebral artery occlusion (MCAO), performed by transiently blocking the arterial blood flow with a removable thread or... 

Compared with brain ischemia spinal cord strokes are caused by more diverse etiologies. Up-to-now there is no satisfactory and accepted classification of spinal infarcts. Etiologies include circulatory arterial and venous disorders. From a clinical and pathoanatomical point of view it seems reasonable to differentiate between acute ischemic myelomalacia and subacute to chronic vascular myelopathy (Table 17.1). In most cases MRI enables the differentiation of these two main etiologies. A deficient spinal arterial blood flow generally has various causes, ranging from the occlusion of intercostal or lumbar arteries to affection of the intrinsic arteries of the spinal cord. ... 

Conventional treatment of raised ICP in this condition consists of artificial ventilation, osmotherapy, and barbiturate administration. The value and duration of these measures has come under scrutiny. Prolonged hyperventilation has been discouraged, as the potential decrease in cerebral arterial blood flow resulting from additional hypocarbia might exacerbate tissue ischemia (34). Early use of agents such as glycerol or mannitol, at least in theory, may actually hasten tissue shifts and therefore lead to an aggravation of brain edema (35). Barbiturate therapy has to date failed to prove to be of therapeutic benefit in the treatment of postischemic brain edema (36). 

Measurements possible in this model include end-diastolic and systolic pressure of the left ventricle, contractility of the heart (usually using peak positive LVdP/dt or LVdP/dt at a developed pressure of 40mmHg), heart rate, cardiac output and arterial blood flow in a given local perfusion bed. Test... 

A pair of rigid stainless-steel wire hook-like electrodes with a distance of 4 mm are adjusted to the artery by means of a rack and pinion gear manipulator. The artery is raised slightly away from the surrounding tissue. Isolation of the electrodes is achieved by the insertion of a small piece of parafilm under the artery. Blood flow is measured with an ultrasonic Doppler flowmeter (Transonic, Ithaca NY, USA) the flow probe (1RB) is placed proximal to the damaged area. 

Fig. 7. Schematic diagram of the canine femoral artery copper coil model of thrombolysis. A thrombogenic copper coil is advanced to either femoral artery via the left carotid artery. By virtue of the favorable anatomical angles of attachment, a hollow polyurethane catheter advanced down the left carotid artery nearly always enters the descending aorta, and with further advancement, into either femoral artery without fluoroscopic guidance. A flexible, Teflon-coated guidewire is then inserted through the hollow catheter and the latter is removed. A copper coil is then slipped over the guidewire and advanced to the femoral artery (see inset). Femoral artery flow velocity is measured directly and continuously with a Doppler flow probe placed just proximal to the thrombogenic coil and distal to a prominent sidebranch, which is left patent to dissipate any dead space between the coil and the next proximal sidebranch. Femoral artery blood flow declines progressively to total occlusion over the next 10-12 mm after coil insertion.

The cardiac effects of intracoronary infusion of cocaine have been studied in dogs and humans (42). The procedure can be performed safely and does not alter coronary arterial blood flow. The effects of direct intracoronary infusion of cocaine on left ventricle systolic and diastolic performance have been studied in 20 patients referred for cardiac catheterization for evaluation of chest pain. They were given saline or cocaine hydrochloride (1 mg/minute) in 15-minute intracoronary infusions, and cardiac measurements were made during the final 2-3 minutes of each infusion. The blood cocaine concentration obtained from the coronary sinus was 3.0 pg/ml, which is similar in magnitude to the blood-cocaine concentration reported in abusers who die of cocaine intoxication. Minimal systemic effects were produced. The overall results were that cocaine caused measurable deterioration of left ventricular systolic and diastolic performance. 

Baumgartner RW (1999). Transcranial color-coded duplex sonography. Journal of Neurology 246 637-647 Baumgartner RW, Mattie HP, Aaslid RC et al (1997). Transcranial colour-coded duplex sonography in arterial cerebrovascular disease. Cerebrovascular Diseases 7 57-63 Bishop CCR, Powell S, Insall MC et al (1986). Effect of internal carotid artery occlusion on middle cerebral artery blood flow at rest and in response to hypercapnia. Lancet i 710-712... 

OrvimU, Roald HE, Stqrhens RW, Roos N, Sakariassen KS Tissue factor-induced coagulation triggers platelet thrombus formation as effidently as fibrillar collagen at arterial blood flow conditions. Arteriosder Hirottd) 14 1976-1983,1994. 

Cardiovascular system. Both caffeine and theophylline directly stimulate the myocardium and cause increased cardiac output, tachycardia and sometimes ectopic beats and palpitations. This effect occurs almost at once after i.v. injection and lasts half an hour. Theophylline contributes usefuUy to the relief of acute left ventricular failure. There is peripheral (but not cerebral) vasodilatation due to a direct action of the drugs on the blood vessels, but stimulation of the vasomotor centre tends to counter this. Changes in the blood pressure are therefore somewhat unpredictable, but caffeine 250 mg (single dose) usually causes a transient rise of blood pressure of about 14/10 mmHg in occasional coffee drinkers (but has no additional effect in habitual drinkers) this effect can be used advantageously in patients with autonomic nervous system failure who experience postprandial hypotension (2 cups of coffee with breakfast may suffice for the day). In occasional coffee drinkers 2 cups of coffee (about 160 mg caffeine) per day raise blood pressure by 5/4 mmHg. Increased coronary artery blood flow may occur but increased cardiac work counterbalances this in angina pectoris. 

Arterial bruit A systolic rushing sound synchronized with the heart beat indicates increased arterial blood flow. This often barely audible sound is easier to discern if one listens for arterial bruit and feels the patient s pulse at the same time. It is sometimes heard where aneurysm or stenosis is present in large arteries (e.g. coeliac artery, hepatic artery) as well as in arteriovenous malformations, highly vascularized liver tumours, pronounced acute alcohol hepatitis, 1-2 days after liver biopsy resulting from temporary arteriovenous fistula, or in twisted arteries in cirrhosis. It is seldom found in healthy persons. (10, 13, 44)... 

Likewise, an attempt was made to eliminate ascites surgically by reducing the portal and arterial blood flow to the liver. This was achieved by arterial ligation in the root zone of the portal vein as well as by ligation of the hepatic artery. The results were disappointing. 

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