In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

[EX Q]: Context: Abnormalities of serum sodium are common after subarachnoid hemorrhage (SAH) and have been linked to poor outcome. This study analyzed whether abnormal serum sodium levels are associated with cardiac outcomes and mortality after subarachnoid hemorrhage (SAH).', "In a prospective cohort study of SAH patients, the primary predictor variable was subjects' sodium level. Hypernatremia was defined as sodium >143 mmol/L and hyponatremia was <133 mmol/L. Cardiac troponin I (cTi) was measured and echocardiography was performed on three study days. Dichotomous outcome variables were cTi > 1.0 microg/L, left-ventricular ejection fraction (LVEF) <50%, presence (vs absence) of regional wall motion abnormalities (RWMA) of the LV, pulmonary edema, and death. Additional analyses studied the degree of hypernatremia and sodium supplementation, and the temporal relationship between hypernatremia and cardiac outcomes.", 'The study included 214 subjects. Forty-eight subjects (22%) were hypernatremic on at least one study day, and 45 (21%) were hyponatremic. After multivariate adjustment, hypernatremia was an independent predictor of LVEF <50% (OR 4.7, CI 1.3-16.2, p = 0.015), elevated cTi (OR 3.7, CI 1.2-11.9, p = 0.028), and pulmonary edema (OR 4.1 CI 1.4-1.5, p = 0.008). It was not, however a statistically significant predictor of mortality (p = 0.075).\Question: Does hypernatremia predict adverse cardiovascular and neurological outcomes after SAH?
[EX A]: In the acute period after SAH, hypernatremia is associated with adverse cardiac outcomes and death. SAH patients with hypernatremia should be monitored for evidence of cardiac dysfunction.

[EX Q]: Context: Although the echolucent plaque in carotid stenosis is associated with future ischemic stroke, the predictive value of echogenicity in small and medium size carotid plaques on vascular events has not been thoroughly examined. Thus, we prospectively tested the hypothesis that plaque echogenicity of carotid atheroma can predict the future total cardiovascular events in patients with vascular risk factors.', 'Ultrasound assessment of carotid intima-media complex thickness (IMT) and plaque echogenicity using integrated backscatter (IBS) analysis was performed in 596 patients aged 40 or more, with any history of vascular events or with at least 1 risk factor, who were enrolled between 2001 and 2006 in the Osaka Follow-up Study for Carotid Atherosclerosis, part 2 (OSACA2). We followed the incidence of total cardiovascular events including cerebrovascular events, coronary heart disease (CHD), and peripheral artery disease (PAD) for 6.4 years. We divided the patients into two groups according to the IBS index above (echorich plaques) and under (echolucent plaque) the median value, and calculated the hazard ratios (HR) of the echolucent group compared with the echogenic group in the risk of cardiovascular events.', 'Among 596 patients, carotid stenosis was found only in 87 patients. During the follow-up period, we observed 121 cardiovascular events including 63 cerebrovascular events, 45 CHD cases, and 13 PAD cases. The patients with incident cardiovascular events had larger plaque thickness and lower IBS index than those without incident vascular events. The relative risk of vascular events for echolucent versus echorich plaques was 1.45 (95% confidence interval [CI] 0.99-2.13, p = 0.058) after adjustment for risk factors and plaque thickness. In patients with plaque size above the median value (>2.1 mm), the relative risk of vascular events for echolucent plaques was 1.72 (95% CI 1.06-2.85, p = 0.029), but this association was not observed in patients with plaque size <2.0 mm.\Question: Does echogenicity of medium-to-large carotid plaques predict future vascular events?
[EX A]: The association between echogenicity of carotid plaque and incident vascular events is dependent on the plaque size. Echolucent medium-to-large plaques, but not small plaques, are associated with the risk of future total cardiovascular events. This finding suggests that measurement of echolucency in medium-to-large carotid plaques may improve selection of patients at high risk for total vascular events.

[EX Q]: Context: To investigate the influence of different phlebotomy postures on clinical chemistry testing.', 'Nineteen volunteers were recruited from the laboratory staff. A first set of samples was drawn after 25 min of resting in supine position, a second after 20 min in sitting position, and a third after 20 min in upright position. Clinical chemistry testing was performed on Roche Cobas C501.', 'The plasma volume change (PVC) was -3.4% from supine to sitting, -14.1% from supine to standing and -9.7% from sitting to standing. Compared to quality specifications for bias, hemoglobin, hematocrit, albumin and total proteins exhibited meaningful increases from supine to sitting, whereas meaningful increases were observed for hemoglobin, hematocrit, albumin, alkaline phosphatase (ALP), amylase, aspartate aminotransferase (AST), total bilirubin, calcium, total and high-density lipoprotein (HDL) cholesterol, gamma-glutamyl transferase (GGT), glucose, lactate dehydrogenase (LDH), magnesium, total protein and triglycerides from sitting to standing. The parameters with meaningful bias from sitting to upright were hemoglobin, hematocrit, albumin, ALP, total bilirubin, calcium, total and HDL cholesterol, glucose, LDH and total protein.\Question: Is postural change during venous blood collection a major source of bias in clinical chemistry testing?
[EX A]:
These results provide further support to the need of standardizing patient's posture during phlebotomy.