Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Context: Preoperative anemia may affect postoperative mortality and morbidity following elective cranial operations.', 'The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was used to identify elective cranial neurosurgical cases (2006-2012). Morbidity was defined as wound infection, systemic infection, cardiac, respiratory, renal, neurologic, and thromboembolic events, and unplanned returns to the operating room. For 30-day postoperative mortality and morbidity, adjusted odds ratios (ORs) were estimated with multivariable logistic regression.', 'Of 8015 patients who underwent elective cranial neurosurgery, 1710 patients (21.4%) were anemic. Anemic patients had an increased 30-day mortality of 4.1% versus 1.3% in non-anemic patients (P < 0.001) and an increased 30-day morbidity rate of 25.9% versus 14.14% in non-anemic patients (P < 0.001). The 30-day morbidity rates for all patients undergoing cranial procedures were stratified by diagnosis: 26.5% aneurysm, 24.7% sellar tumor, 19.7% extra-axial tumor, 14.8% intra-axial tumor, 14.4% arteriovenous malformation, and 5.6% pain. Following multivariable regression, the 30-day mortality in anemic patients was threefold higher than in non-anemic patients (4.1% vs 1.3%; OR = 2.77; 95% CI: 1.65-4.66). The odds of postoperative morbidity in anemic patients were significantly higher than in non-anemic patients (OR = 1.29; 95% CI: 1.03-1.61). There was a significant difference in postoperative morbidity event odds with a hematocrit level above (OR = 1.07; 95% CI: 0.78-1.48) and below (OR = 2.30; 95% CI: 1.55-3.42) 33% [hemoglobin (Hgb) 11 g/dl].
Answer: Preoperative anemia in elective cranial neurosurgery was independently associated with an increased risk of 30-day postoperative mortality and morbidity when compared to non-anemic patients. A hematocrit level below 33% (Hgb 11 g/dl) was associated with a significant increase in postoperative morbidity.
Does preoperative anemia increase postoperative morbidity in elective cranial neurosurgery?

Context: 99mTc-HMPAO is a well-established isotope useful in the detection of regional cerebral blood flow. Diabetes gives rise to arterial atherosclerotic changes that can lead to significant end organ dysfunction, prominently affecting perfusion to the heart, kidneys, eyes and brain. In the current study, we investigated the role of 99mTc-HMPAO cerebral perfusion scans in detecting early vascular changes in the diabetic brain.', 'Cerebral perfusion studies were performed on both control and streptozotocin-(STZ) induced diabetic male Wistar rats. Rat brain imaging using a gamma camera was performed for each group 0.5, 2, 4, and 24 hours post 99mTc-HMPAO injection. Data processing for each cerebral perfusion scan was performed by drawing a region of interest (ROI) circumferentially around the brain (B). Background (BKG) due to signal from the soft tissue of each rat was subtracted. Brain 99mTc-HMPAO uptake minus background counts (net brain counts; NBC) were then compared between the two groups.', 'The NBC (mean +/- SD) for the STZ group were statistically significantly higher (p = 0.0004) than those of the control group at each of the time points studied.
Answer: 99mTc-HMPAO brain scan may be useful in the detection of early atherosclerotic changes in the diabetic rat brain.
Does perfusion scanning using 99mTc-HMPAO detect early cerebrovascular changes in the diabetic rat?

Context: Because of the immunomodulatory effects of transfusion, we attempted to identify factors associated with blood product use and determine the association of transfusion quantity with postoperative infection.', 'We studied total perioperative transfusion of blood products for 15,592 cardiovascular operations performed from July 1998 to May 2003. Infection end points were septicemia/bacteremia (n=351, 2.2%) and superficial (n=353, 2.3%) and deep (n=212, 1.4%) sternal wound infections. Factors associated with blood product administration were used to form balancing scores to adjust for differences in patient characteristics among those receiving and not receiving blood products.', 'Fifty-five percent of patients received packed red blood cells (RBC), 21% received platelets, 13% got fresh frozen plasma (FFP), and 3% got cryoprecipitate. Factors associated with RBC use included older age, female gender, higher New York Heart Association class, lower hematocrit, reoperation, and longer cardiopulmonary bypass time--all indicative of higher-risk patients. The more RBC units transfused, the higher was the occurrence of septicemia/bacteremia (p < 0.0001) and superficial (p=0.0007) and deep (p < 0.0001) sternal wound infection. Use of FFP (septicemia/bacteremia) and platelets (septicemia/bacteremia and deep sternal wound infection) mitigated against this association only slightly.
Answer: Blood products tended to be used in the sickest patients. But after accounting for this, risk of infection increased incrementally with each unit of blood transfused. Although cause and effect cannot be established, results suggested that blood product transfusion is an independent risk factor for postoperative infection in cardiac surgical patients, blood products are more likely to be used in the sickest patients, and no amount of blood loss treated by transfusion is innocuous.

Does transfusion increase the risk of postoperative infection after cardiovascular surgery?