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

Controversy exists as to whether plasma volume (PV) expansion has the potential to increase maximal oxygen uptake (VO2max). In the present study, VO2max and exercise time to fatigue were measured in nine untrained men when plasma volume (PV) was normal and then again on the next day following two levels of PV expansion. Resting PV was expanded (via intravenous infusion of a 6% dextran solution) by 282 +/- 16 ml (i.e., PVX-1) and then by 624 +/- 26 ml (i.e., PVX-2). PVX-1 increased stroke volume (CO2 rebreathing) during submaximal exercise by 15% (P less than 0.05) above normal levels. VO2max following PVX-1 was increased 4% (P less than 0.05; 3.78 to 3.92 l/min) despite a 4% reduction in hemoglobin concentration. Exercise time to fatigue was also increased (P less than 0.05). PVX-2 resulted in an 11% (P less than 0.05) reduction in hemoglobin concentration during maximal exercise and a return of VO2max and exercise time to normal levels. In summary, we have observed in untrained men that 200-300 ml of PV expansion increases SV, measured during submaximal exercise, yet causes only a small amount of hemodilution. As a result, VO2max is increased slightly and performance is improved. Further PV expansion to levels 500-600 ml above normal results in an excessive hemodilution and a subsequent decline in VO2max and performance to normal levels. There is an optimal PV for eliciting VO2max in untrained men which appears to be approximately 200-300 ml above their normal levels.
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PMID:Maximal oxygen uptake relative to plasma volume expansion. 169 70

In 40 patients, whose expected hemodynamic instability during surgery necessitated invasive monitoring (Swan-Ganz catheter) and arterial pressure monitoring the hemodynamic and oxygen transport parameters in conditions of hypervolemic hemodilution were investigated in randomized tests. After insertion of an arterial catheter (arteria radialis) as well as Swan-Ganz pulmonary arterial catheter via the vena jugularis interna, one of the two volume substitutes selected at random was infused in quantities of 125 ml/5 min and the hemodynamic changes were measured after infusion of 500 ml and finally after a wedge pressure of 18 mmHg was reached. Using either solution, the measurements indicated significant increases in mean arterial pressure as well as in central venous pressure (ZVD) and wedge pressure. The cardiac index, left ventricular stroke work index, and stroke output rose consecutively and pulmonary vascular resistance went down in both test groups. In the case of both volume substitutes, there was an improvement in oxygen availability. The hemoglobin content decreased in both groups, though to different degrees in each group. Although the hydroxyethyl starch group registered a greater improvement in the cardiac index, a bigger decrease in pulmonary vascular resistance, a higher rise in the left ventricular stroke work index and a more significant improvement in stroke output, smaller quantities of the volume substitute were required in this group than in the group in which volume substitution was carried out with human albumin 5%.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Comparative study of the intraoperative effectiveness of 5% human albumin or 10% hydroxyethyl starch (HAES-steril) on hemodynamics and oxygen transport in 40 patients]. 169 83

The effects of propranolol and hemodilution on myocardial performance and oxygen delivery were evaluated in 36 anesthetized rats. Oral propranolol treatment consisted of 64 mg/kg/d for 6 weeks prior to the experiments, whereas intravenous (IV) propranolol treatment consisted of 5 micrograms/kg/min for 60 minutes after hemodilution. The hematocrit was reduced to 20% by a hetastarch-for-blood exchange. Animals were divided into six equal groups as follows: (1) no oral drug (water), no hemodilution, no IV drug (saline); (2) oral water, hemodilution, IV saline; (3) oral water, no hemodilution, IV propranolol; (4) oral water, hemodilution, IV propranolol; (5) oral propranolol, no hemodilution, IV saline; and (6) oral propranolol, hemodilution, IV saline. Left ventricular (LV) pressure, maximal dP/dt, ascending aortic blood flow, and response to preload (peak cardiac and stroke volume indices) and afterload (LV-developed pressure) stress were measured. In group 2, hemodilution significantly increased cardiac index, stroke volume index, and dP/dt, and decreased blood pressure, peripheral resistance, and oxygen delivery compared with group 1. Compared with group 2, IV propranolol after hemodilution in group 4 significantly decreased cardiac index, dP/dt, LV-developed pressure, and peak cardiac index, and increased peripheral resistance. Stroke volume index and peak stroke volume index after preload stress remained elevated in group 4, despite the negative inotropic effects of IV propranolol. Oral propranolol in group 6 did not prevent the hemodilution-induced increase in stroke volume index and peak stroke volume index in response to preload stress, although it did decrease cardiac index and dP/dt compared with group 2. Oxygen delivery was reduced in the hemodiluted animals in proportion to the decrease in hemoglobin, regardless of propranolol treatment. It is concluded that reduced myocardial contractility and cardiac performance by nonselective pharmacological beta-adrenoceptor blockade does not interfere with the compensatory increase in stroke volume index after hemodilution.
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PMID:Effects of propranolol on myocardial performance during acute normovolemic hemodilution. 171 11

Conventional fluid resuscitation is unsatisfactory in a small percentage of equine emergency surgical cases because the large volumes of fluids required cannot be given rapidly enough to adequately stabilize the horse. In anesthetized horses, the volume expansion and cardiopulmonary effects of a small volume of highly concentrated hypertonic saline-dextran solution were evaluated as an alternative initial fluid choice. Seven halothane-anesthetized, laterally recumbent, spontaneously ventilating, normovolemic horses were treated with a 25% NaCl-24% dextran 70 solution (HSD) at a dosage of 1.0 ml/kg of body weight, IV, infused over 10 minutes, and the effects were measured for 120 minutes after infusion. Plasma volume expansion was rapid and significant (from 36.6 +/- 4.6 ml/kg to 44.9 +/- 4.8 ml/kg), and remained significantly expanded for the duration of the experiment. Packed cell volume, total blood hemoglobin, and plasma protein concentrations significantly decreased, confirming rapid and sustained volume expansion with hemodilution. Cardiac index and stroke index immediately increased and remained high for the entire study (from 69.6 +/- 15.3 ml/min/kg to 106.6 +/- 28.4 ml/min/kg, and from 1.88 +/- 0.49 ml/beat/kg to 2.50 +/- 0.72 ml/beat/kg, respectively). Systemic vascular resistance significantly decreased immediately after HSD infusion and remained decreased for the duration of the study (from 1.41 +/- 0.45 mm of Hg/ml/min/kg to 0.88 +/- 0.22 mm of Hg/ml/min/kg). Arterial and venous blood oxygen content decreased significantly because of hemodilution, but actual oxygen transport transiently increased at the 10-minute measurement before returning toward baseline.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of a highly concentrated hypertonic saline-dextran volume expander on cardiopulmonary function in anesthetized normovolemic horses. 172 55

In 80 patients with moderate hypertension the effects of nisoldipine 10 mg b.i.d., nifedipine 10 mg and 20 mg t.i.d., diltiazem 60 mg and 120 mg t.i.d., and verapamil 40 mg q.i.d. (all after single dose and 14 days' treatment) on blood pressure; hemodynamic parameters (cardiac output, stroke volume, left ventricular ejection fraction, and total peripheral resistance); and red blood cell and platelet functional state parameters (platelet aggregation, erythrocytal mechanical resistance, and free hemoglobin and ADP levels in plasma) were studied. All of the drugs studied in doses mentioned produced statistically significant hypotensive effects. Nifedipine 20 mg and nisoldipine 10 mg produced the most peripheral vasodilatator activity after a single dose and chronic treatment. Diltiazem had the same effect only in doses of 120 mg and after chronic treatment. However, all the drugs significantly normalized the red blood cell and platelet functional state disturbances in 70-80% of patients with moderate hypertension, even 2 h after a single dose. Disaggregation effect was parallel to clinical improvement. These data make it possible to predict the individual response of most patients to antihypertensive drugs on the basis of acute pharmacological tests, with determination of disaggregation effect.
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PMID:The effects of nisoldipine, diltiazem, nifedipine, and verapamil on hemodynamic parameters and red blood cells-platelet interactions in patients with arterial hypertension. 172 40

A collaborative study was conducted to measure the cardiocirculatory responses to upright tilt in eight young men at sea level (SL); after 1h at 4300m simulated altitude (SA) and at 18h, 66h and 114h during residence at 4300m (HA). Heart rate (HR), stroke volume (SV), cardiac output (CO), calf blood flow (CBF), blood pressure (BP) and total peripheral resistance (TPR) were obtained during supine rest and after 13 min of 60 degrees head-up tilt using an impedance monitor and an electrosphygmomanometer. SL to HA changes in blood volume (BV) were calculated from hematocrit and hemoglobin values. Supine HR, TPR and BP were increased while SV, CO and CBP were reduced SL to HA (P less than .05). HR and BP in the upright position were increased SL to HA (P less than .05). The responses to tilt (delta supine to upright) were unaltered SL vs SA. With prolonged exposure, SV, CO, TPR and CBP responses to tilt were reduced (P less than .05). The reduced responses to tilt at HA were associated with a 10% decline in BV (P less than .01). It was concluded that the reduction in SV during tilt at SL and SA was compensated for by increases in HR and TPR in order to maintain BP. After 18h HA, BP in the upright position was maintained only by an increase in HR.
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PMID:Cardiocirculatory responses to upright tilt at sea level and high altitude. 177 May 61

There is wide variation in the clinical manifestations of sickle cell disease (SCD) from one affected individual to another. Many investigators have sought to discern parameters that would explain this variability. In the present studies we have attempted to correlate the frequency of painful events and the extent of end organ failure in SCD with rheologic properties of packed suspensions of sickle cells, using a magneto-acoustic ball microrheometer developed in our laboratory. Using this device we have measured the steady-state viscosity, and the viscous and elastic moduli of cell suspensions in 16 individuals with hemoglobin SS disease who were untransfused and in their steady state. The rheologic parameters were then correlated with clinical parameters. The clinical parameters measured were emergency department visits, hospitalizations, hemoglobin, reticulocyte count, age, and end organ failure (nephropathy, avascular necrosis of bone, stroke, retinopathy, resting hypoxemia after acute chest syndrome(s), leg ulcer, and priapism with impotence). The P value for the correlation between the steady state viscosity and end organ failure was .001 with a correlation coefficient (R value) of .73. The P value for the correlation between the viscous modulus of viscosity and end organ failure was .00006 with an R value of .83. The P value for the correlation between the elastic modulus of viscosity and end organ failure was .0006 with an R value of .76. However, there was no significant correlation between any component of packed cell rheology and emergency department visits or hospitalizations for pain.
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PMID:Relationship of clinical severity to packed cell rheology in sickle cell anemia. 182 65

We analyzed the serum concentrations of lipids and lipoproteins and the prevalence of other risk factors in a case-control study of 304 consecutive Chinese patients with acute stroke (classified as cerebral infarction, lacunar infarction, or intracerebral hemorrhage) and 304 age- and sex-matched controls. For all strokes we identified the following risk factors: a history of ischemic heart disease, diabetes mellitus, or hypertension; the presence of atrial fibrillation or left ventricular hypertrophy; a glycosylated hemoglobin A1 concentration of greater than 9.1%; a fasting plasma glucose concentration 3 months after stroke of greater than 6.0 mmol/l; a serum triglyceride concentration 3 months after stroke of greater than 2.1 mmol/l; and a serum lipoprotein(a) concentration of greater than 29.2 mg/dl. We found the following protective factors: a serum high density lipoprotein-cholesterol concentration of greater than 1.59 mmol/l and a serum apolipoprotein A-I concentration of greater than or equal to 106 mg/dl. The patterns of risk factors differed among the three stroke subtypes. When significant risk factors were entered into a multiple logistic regression model, we found a history of hypertension, a high serum lipoprotein(a) concentration, and a low apolipoprotein A-I concentration to be independent risk factors for all strokes. The attributable risk for hypertension was estimated to be 24% in patients aged greater than or equal to 60 years. In this population, in which cerebrovascular diseases are the third commonest cause of mortality, identification of risk factors will allow further studies in risk factor modification for the prevention of stroke.
Stroke 1991 Feb
PMID:Hypertension, lipoprotein(a), and apolipoprotein A-I as risk factors for stroke in the Chinese. 192 51

I have traced the development of the optical method from Millikan's colorimetry of cat muscle myoglobin to today's high-frequency laser diode time-resolved phase modulation system study of hemoglobin and myoglobin in muscle and brain in adult humans. The path length as well as specific absorption information is obtained in terms of the rate of photon decay or by equivalent measurements using phase modulation. Localization of inhomogeneities of deoxyhemoglobin concentrations in stroke and head injury appears possible.
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PMID:Optical method. 186 11

In two patients with carotid artery stenosis and anemia, neurological deficits appeared whenever the hemoglobin level fell below a critical level of 5-6 g/dl and resolved with correction of the anemia. Profound anemia should be considered as a cause of focal neurological deficit, especially if there is evidence of cerebral atherosclerosis.
Stroke 1991 Sep
PMID:Severe anemia associated with transient neurological deficits. 192 64


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