Journal of critical care
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Journal of critical care · Dec 1996
Reversal of muscle fatigue in intact rabbits by intravenous potassium chloride.
Skeletal muscle fatigue has been associated with potassium efflux from the myocytes, resulting in endogenous increases in blood potassium concentration ([K+]). Conversely, exogenous increases in extracellular [K+] potentiates contraction in isolated muscle preparations. The mechanisms responsible for these contradictory effects of [K+] on skeletal muscle function are unknown. Moreover, little is known about the effect of exogenous increases in [K+] on force generation by intact animals, given potassium's deleterious effect on cardiac function. ⋯ Exogenous increases in blood [K+] potentiate skeletal muscle contraction in intact animals and reverse low-frequency twitch fatigue. A possible mechanism may be the maintenance of intracellular [K+] by hindering K+ efflux from skeletal muscle cells.
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Journal of critical care · Dec 1996
Clinical TrialEffect of passive range of motion on intracranial pressure in neurosurgical patients.
A prospective patient study was done to evaluate the effect of passive range of motion (PROM) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in neurosurgical patients. ⋯ PROM results in no significant changes in ICP or CPP in stable, neurosurgical patients in the absence of intracranial hypertension.
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The increase of cardiac output (CO) in sepsis must be matched by an increase in venous return. Our goal was to determine which of the determinants of venous return are responsible in volume-loaded and nonvolume-loaded pigs with endotoxemia. The determinants include stressed volume, venous compliance (Cv), venous resistance (RVR) and right atrial pressure (Pra). We also tested the effect of the nitric oxide (NO) synthase inhibitor, N omega-nitro-L-arginine-methyl ester (L-NAME) after the hemodynamics with endotoxin stabilized. ⋯ Changes in vascular tone during endotoxemia are dependent on volume status. The increased cardiac output in volume-treated septic animals occurred because of an increase in stressed volume due to the volume given in combination with a dilated vasculature. L-NAME restored arterial tone but decreased CO because of a rise in RVR and decrease in cardiac function.
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Journal of critical care · Dec 1996
Central venous pressure, pulmonary artery occlusion pressure, intrathoracic blood volume, and right ventricular end-diastolic volume as indicators of cardiac preload.
Central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP) and right ventricular end-diastolic volume (RVEDV) are often regarded as indicators of both circulating blood volume and cardiac preload. to evaluate these relationships, the response of each variable to induced volume shifts was tested. The relationships between these variables and cardiac index (CI) and stroke volume index (SVI) was also recorded to assess the utility of each variable as an indicator of cardiac preload. The responses of the new variable intrathoracic blood volume (ITBV) to the same maneuvers was also tested. To examine the effects of changes in cardiac output alone on ITBV, the effects of infusing dobutamine were studied. ⋯ Under the experimental conditions chosen neither CVP, PAOP, nor RVEDV reliably indicated changes in circulating blood volume, nor were they linearly and tightly correlated to the resulting changes in SVI. ITBV reflected both changes in volume status and the resulting alteration in cardiac output. The possibility that ITBV might be cardiac output-dependent was not supported. ITBV, therefore, shows potential as a clinically useful indicator of overall cardiac preload.
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Journal of critical care · Dec 1996
Anti-CD18 antibodies improve cardiac function following cardiopulmonary bypass in dogs.
Cardiopulmonary bypass is associated with activation of neutrophils, which may adhere to vascular endothelium causing lung, heart, and brain injury. We tested whether blocking neutrophil adherence would improve organ function following cardiopulmonary bypass in dogs. ⋯ Monoclonal antibodies to CD18 can prevent the deterioration in cardiac function routinely observed following cardiopulmonary bypass.