Bottom line: Both BID and TID dosing of UFH are acceptable thromboprophylaxis regimens in hospitalized medical patients with no difference in effect on DVT, PE, major bleeding, or death.
Citation: Phung OJ, Kahn SR, Cook DJ, et al. Dosing frequency of unfractionated heparin thromboprophylaxis: a meta-analysis. Chest. 2011;140: 374-381.
New Cardiac-Risk Calculator Improves Prediction of Intra-/Postoperative Myocardial Infarction and Cardiac Arrest
Clinical question: Can a more accurate risk calculator than the Revised Cardiac Risk Index (RCRI) be developed and validated to predict postoperative cardiac events?
Background: The majority of perioperative deaths are secondary to cardiac-related events. The RCRI is the most commonly used preoperative risk stratification tool, but it has limitations and low discriminatory ability.
Study design: Multicenter prospective National Surgical Quality Improvement Program database study.
Setting: More than 250 academic and community U.S. hospitals.
Synopsis: Data were obtained from patients over a two-year period (2007 and 2008). From the 2007 data set (n=211,410), perioperative myocardial infarction or cardiac arrest (MICA) was seen in 1,371 patients (0.65%). After multivariate analysis on the 2007 data set, five risk predictors were obtained (increasing age, American anesthesiology class, dependent functional status, abnormal serum creatinine of >1.5 mg/dL, and type of surgery). This was validated utilizing the 2008 data set (n=257,385), where MICA was seen in 1,401 patients (0.54%).
The risk-predictive model showed excellent discrimination (distinguishing between events and nonevents) after application of C statistics to the dataset. The discriminatory ability was better when compared with the RCRI model. Limitations included nonavailability of information on preoperative stress test, arrhythmia, and aortic valve disease.
Bottom line: The new risk calculator model would help predict MICA more accurately, which in turn would help in preoperative optimization and patient counseling.
Citation: Gupta PK, Gupta H, Sundaram A, et al. Development and validation of a risk calculator for prediction of cardiac risk after surgery. Circ. 2011;124:381-387.
Third-Generation CT Scans are Very Sensitive in Detecting Subarachnoid Hemorrhage
Clinical question: Are modern third-generation CT scans good enough to exclude subarachnoid hemorrhage (SAH) without a lumbar puncture (LP)?
Background: SAH is a neurosurgical emergency identified in about 1% of patients with headache in the emergency department. As the standard of care, all patients with suspected SAH have to undergo LP if a CT scan of the brain is normal. However, LP causes pain and delays discharge from the emergency department.
Study design: Prospective multicenter cohort study.
Setting: Eleven tertiary-care Canadian emergency departments.
Synopsis: From November 2000 to December 2009, data on all alert patients (n=3,132) who presented with acute headache and underwent emergent head CT were collected. Of these, 240 had SAH (7.7%). The sensitivity of CT overall for detecting SAH was 92.9% and the specificity was 100%. For the 953 patients scanned within six hours of headache onset, all 121 patients with SAH were identified by CT, yielding a sensitivity of 100% and specificity of 100%.
The study was limited largely by the lack of a consensus definition on the diagnosis of SAH and by some patient enrollment issues in the emergency department. Overall, these findings should give clinicians more confidence in forgoing an LP in patients with a negative head CT if done within six hours of the onset of their headache.
Bottom line: Modern third-generation CT scans are extremely sensitive for SAH if performed within six hours of the headache onset and interpreted by a qualified radiologist, thus possibly excluding the need for an LP.