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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By use of the impedance noninvasive method, cardiac output (Q), stroke volume (SV), heart rate (HR), Heather index (HI), and systolic time interval (STI) values were studied in 17 subjects working at 25, 50, and 75% of their maximal oxygen uptake (Vo2 max) on a Monark bicycle. A significant increase in SV at each work load and a concomitant decrease in positive expiratory pressure (PEP), left ventricular ejection time (LVET), and PEP/LVET were observed. The linear regression equation at 75% Vo2 max between LVET and HR and SV confirms the close relationship between these parameters. The significa-t increase of the contractility index (HI) showing the stress response of the myocardium is clearly assessed. At 75% work load, its correlation with SV is low; but the high level of the correlation (r = 0.90) between HI and HR in the stress response. Consequently the changes in STI and HI provide valuable information on SV adjustment during calibrated effort responses. Consequently, the changes in STI and HI, the relationship between STI and SV, and the study of SV, HR, and Q provide valuable information about the adjustment of these parameters during calibrated efforts.
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PMID:Stroke volume and systolic time interval adjustments during bicycle exercise. 43 31

Cardiac output, using dye-dilution technique, and intra-arterial blood pressure at rest and during exercise on a bicycle ergometer were determined in six boys with bronchial asthma, mean age 11.9 years. Intra-arterial blood pressure was also measured in another group of eight boys with bronchial asthma. Cardiac output, stroke volume, arteriovenous oxygen difference, blood pressure and total peripheral vascular resistance at rest and during exercise up to maximal level were within the normal limits of healthy boys of the same age. At maximal exercise, cardiac output averaged 12.4 l/min, stroke volume 66 ml, systolic, diastolic and mean blood pressures 128, 81 and 107 mmHg, respectively, and total peripheral vascular resistance 10.9 mmHg/l/min. The maximal arteriovenous oxygen difference amounted to 14.1 ml/100 ml blood which is similar to that in healthy adults.
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PMID:Cardiac output and blood pressure at rest and during exercise in boys with bronchial asthma. 44 97

Physostigmine, at 0.1, 0.2 and 0.3 mg/kg, was tested for effect on the survival of mice exposed to 5% O2-95% N2. Some treated animals survived for one hour under the hypoxic atmosphere (2 out of 14 at 0.1 mg/kg and 8 out of 28 at 0.2 and 0.3 mg/kg), an event never observed in untreated controls. The physostigmine-treated animals that died before the hour showed a dose-related increase in survival time from 4.3 min (untreated controls) to 27.6 min (0.3 mg/kg physostigmine). The effect of physostigmine may be related to its reported ability to increase cerebral blood flow and decrease cerebral oxygen consumption
Stroke
PMID:Physostigmine-induced cerebral protection against hypoxia. 44 38

Vasopressin has been used with increasing frequency to control gastrointestinal bleeding, the beneficial effect being attributed to marked splanchnic vasoconstriction. Because vasopressin may result in impaired cardiac function and because other potent vasoconstrictive substances have been shown to increase the pulmonary shunt and decrease arterial oxygenation, this study was undertaken to determind the effect of vasopressin on oxygen availability. Ten healthy anesthetized mechanically ventilated dogs received a five hour intravenous vasopressin infusion, 0.005 U/kg/min. The heart rate decreased moderately and briefly. The mean systemic arterial pressure increased and then decreased, both minimally. The pulmonary shunt and the arterial oxygen content decreased slightly. The total systemic resistance increased and the stroke volume decreased, both substantially. The pulmonary artery wedge pressure gradually increased. The oxygen availability decreased markedly. This study demonstrated that a vasopressin infusion causes a marked decrease in oxygen availability due primarily to a decreased stroke volume and, to a lesser extent during the first hour, to a decreased heart rate. The pulmonary shunt did not increase. Increased systemic resistance followed by a gradual increase in the pulmonary wedge pressure suggests that the decreased stroke volume resulted, at least in part, from an increased afterload and left ventricular failure. It is suggested that until the effect of vasopressin on the cardiopulmonary systems and hence oxygen availability is fully studied in critically ill patients, that it be used with caution and with appropriate hemodynamic monitoring.
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PMID:The effect of vasopressin on oxygen availability. 44 98

The effects on the circulation of limited normovolaemic haemodilution with dextran 70 and subsequent haemorrhage to a mean arterial pressure of 60 mm Hg were studied with isotope-labelled microspheres in the dog. Following haemodilution, cardiac output, stroke volume and systemic oxygen transport increased. The distribution of oxygen to the heart, liver (hepatic artery), spleen and carcass (mainly muscle, skeleton and skin) was increased, while a decrease in oxygen supply to the brain was found. Following haemodilution and haemorrhage, cardiac output, systemic oxygen transport and mixed venous oxygen tension decreased. Blood flow was redistributed to maintain the cerebral, renal, hepatic arterial and coronary circulations, mainly at the expense of blood flow to the carcass and through systemic arterio-venous shunts. Thus, limited normovolaemic haemodilution does not affect the normal circulatory response to moderate haemorrhagic hypotension.
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PMID:Regional blood flow in normovolaemic and hypovolaemic haemodilution. An experimental study. 44 42

Noninvasive measurements of maximal oxygen intake and invasive measurement of systemic and pulmonary arterial pressures, arterial and mixed venous oxygen contents and direct Fick cardiac output are reported for 3 healthy men and 14 men with coronary heart disease. Observations were obtained at supine and sitting rest, during graded levels of upright exercise on a treadmill up to symptom-limited maximal effort and in two periods of recovery. The effects of 40 mg of propranolol orally were ascertained by repeating the measurements 1 to 1 1/2 hours later. The most consistent effect of propranolol was reduction of pressure-rate products at all phases; slowing of heart rate was significant only during exercise and recovery, and the greater slowing was accompanied by a significant increase in stroke volume. These changes were similar in patients with and without evidence of left ventricular impairment greater than 15 percent on exercise testing. Maximal oxygen intake decreased in healthy subjects and decreased slightly in patients with coronary heart disease with less than 15 percent left ventricular impairment or percent deviation of pressure-rate product from age-predicted normal values during the control study. Maximal oxygen intake increased in patients with more than 15 percent left ventricular impairment. Arterial-mixed venous oxygen difference increased after propranolol because of a reduction of mixed-venous oxygen content attributed to greater peripheral extraction of oxygen.
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PMID:Acute effects of oral propranolol on hemodynamic responses to upright exercise. 45 38

The inotropic effects of albumin were studied in 94 seriously injured patients who received an average of 14.5 transfusions, 9.2 liters of crystalloid and 0.9 liters of plasma prior to end of operation; 46 patients, by random selection, received added albumin averaging 31 gm during operation, 198 gm during the early postoperative period of extravascular fluid sequestration, and 395 gm during the first 4 days of the later fluid mobilization period. Left ventricular stroke work index (LVSWI) was plotted against pulmonary wedge pressure (Ppw) in 22 patients who had indwelling thermistor pulmonary artery catheters at the time of the first study. Calculated heart work units (WU) were derived from the pulse pressure, mean arterial pressure, pulse rate, and central venous pressure (CVP) in patients without LVSWI measurements. Albumin supplementation increased serum albumin (4.2 vs. 2.9 gm%), plasma volume, CVP (15 vs. 9 cm H2O), but did not alter red cell volume (1,531 vs. 1,519 ml). The ratio of LVSWI/Ppw fell in albumin patients (1.9 +/- 1.6 vs. 4.8 +/- 1.8), and the ratio of WU/CVP was significantly depressed in albumin patients (4.9 +/- 2.3 vs. 7.3 +/- 2.1). The slopes of the LVSWI/Ppw and WU/CVP were shifted to the right in albumin patients. This negative inotropic effect was associated with impaired oxygenation, as reflected by an increased ratio of inspired oxygen per arterial oxygen tension (0.62 +/- 0.06 vs. 0.33 +/- 0.1). Finally, 24 of the 46 albumin-treated patients were digitalized for heart failure, compared to only 11 of the 48 nonalbumin patients. Pending subsequent studies, albumin should be considered a potentially negative inotropic agent.
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PMID:Negative inotropic effect of albumin resuscitation for shock. 46 73

Systemic and coronary haemodynamic measurements have been made in six healthy greyhounds anaesthetized with trichloroethylene. The administration of ketamine in bolus doses of 5 mg/kg, 10 mg/kg and 5 mg/kg followed by an infusion 0.1 mg/kg/min was found to be accompanied by a decrease in arterial pressure and an increase in cardiac output produced by an increase (84%) in stroke volume. Coronary blood flow increased greatly as did myocardial oxygen consumption and there was no change in myocardial oxygen extraction.
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PMID:The effects of ketamine on the canine coronary circulation. 48 16

Twenty-four pigs were studied to assess the effect of potassium in a cardioplegic solution on the ability of the swine myocardium to maintain functional and metabolic integrity following induced ischemia. The pigs were evaluated on total and right heart bypass with measurement at normothermia and after a one-hour intervention of stroke volume (SV), coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and lactate extraction. Myocardial tissue gases (PmO2 and PmCO2) were continuously monitored and, at the conclusion of the procedure tissues were analyzed for adenosine triphosphate (ATP). There were five interventions: (1) hypothermic perfusion (28 degrees C) (Group 1); (2) hypothermic ischemia (28 degrees C) (Group 2); and hypothermic ischemia with a cardioplegic solution (nonlactated Ringer's solution, pH 7.4, 4 degrees C) using (3) normokalemia (4 mEq of potassium chloride/L, 300 mOsm/L (Group 3), (4) hyperkalemia (43 mEq of KCl/L, 390 mOsm/L) (Group 4), and (5) normokalemia with increased osmolarity (3.6 mEq of KCl/L, 400 mOsm/L) (Groups 5). A significant decrease in SV and elevation in peak PmCO2 were seen in all groups subjected to ischemia except those protected with hyperkalemic solution. We conclude that the presence of hyperkalemia in a cold root perfusion solution provides better myocardial protection than cold root perfusion alone. Furthermore, potassium arrest appears to be more protective than coronary perfusion at 28 degrees C.
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PMID:The importance of hyperkalemia in a cold perfusion solution: a correlative study examining myocardial function, metabolism, tissue gases, and substrates. 48 29

After severe ischemic injury, it is usually necessary to prolong bypass to enhance recovery. This study tests the hypothesis that the best reversal of ischemic damage is achieved by briefly rearresting the postischemic heart with a continuous infusion of an oxygenated cardioplegic solution (secondary blood cardioplegia) during the period when bypass must be prolonged. Twenty dogs underwent 45 minutes of normothermic ischemic arrest. Fifteen minutes after unclamping, no heart could support the systemic circulation. In all dogs, oxygen demands were lowered by extending bypass for 30 minutes. In 10 of these dogs, demands were further lowered by rearresting the heart for 5 minutes with a continuous infusion of a 37 degrees C blood cardioplegic solution (K+28 mEq/L; pH 7.6; Ca++ 1 mEq/L) at a pressure of 50 mm Hg. Hearts treated with secondary blood cardioplegia showed greater recovery in the rate of contraction (-dP/dt 75% versus 62%, p less than 0.05) and relaxation (-dP/dt 76% versus 58%, p less than 0.05), better recovery of compliance (85% versus 51%, p less than 0.05), a higher stroke work index (0.72 versus 0.50 gm-m/Kg, p less than 0.05), and more ability to augment oxygen uptake (85% versus 45%, p less than 0.05) to meet the demands of the working heart than hearts treated by prolonging bypass alone. We conclude that rearresting the heart with a brief, continuous infusion of a blood cardioplegic solution results in more complete reversal of ischemic damage than possible by prolongation of a bypass alone. We believe that the increased recovery with secondary cardioplegia results from diversion of delivered oxygen toward reparative processes rather than its being expended needlessly on electromechanical work during the time when bypass must be prolonged.
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PMID:Reversal of ischemic damage with secondary blood cardioplegia. 49 22


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