Study design: Prospective study.
Setting: ED of a university-based hospital in Madrid.
Synopsis: CT angiography was performed on 47 ED patients (27 men, 20 women, with a mean age of 68 years) with an acute lower GI bleed. Study protocol included a preliminary unenhanced CT scan followed by CT angiogram prior to the standard clinical protocol, which included colonoscopy, angiography, or laparotomy.
Images were reviewed by two different ED radiologists, who were blinded to the diagnosis, and compared with the standard protocol findings. CT angiography correctly identified active acute or recent GI bleeding in 46 of the 47 patients, with a sensitivity of 100% (19 of 19), NPV of 100% (27 of 27), specificity of 96% (27 of 28), and PPV of 95% (19 of 20). CT angiography also was 93% accurate in identifying the cause of the GI bleed when compared with the standard reference.
Limitations of the study include its small size and the lack of a control group.
Bottom line: CT angiography is an accurate and more readily available modality for the diagnosis of acute lower GI bleeding, though it does not provide a therapeutic option.
Citation: Martí M, Artigas JM, Garzón G, Alvarez-Sala R, Soto JA. Acute lower intestinal bleeding: feasibility and diagnostic performance of CT angiography. Radiology. 2012;262:109-116.
Substitution of Levalbuterol to Avoid Tachyarrhythmia Not Supported
Clinical question: Does substitution of levalbuterol for albuterol in critically ill adult patients result in decreased incidence of tachyarrhythmias?
Background: Studies have indicated an increased risk of mortality from tachycardia and tachyarrhythmias in ICU patients. Levalbuterol is the R-isomer of albuterol, and it has been proposed that it may mitigate cardiac side effects seen with beta-2 agonists. For this reason, some clinicians have advocated using nebulized levalbuterol in critically ill patients.
Study design: Prospective randomized controlled trial with patient crossover.
Setting: Single academic medical center.
Synopsis: All ICU patients in a single teaching hospital were screened, and 70 patients were included. Patients were randomly crossed over between albuterol and levalbuterol every four to six hours. This resulted in a total of 836 measurements of heart rate, the primary outcome measurement. The study showed no clinically significant differences in average heart rate when using levalbuterol versus albuterol. This was a small study of ICU patients, using a surrogate endpoint of heart rate rather than mortality. Furthermore, the assessment of tachyarrhythmias was limited given the study size and relative rarity of these events. Despite these limitations, the study casts significant doubt on the theory and practice of switching from albuterol to levalbuterol solely for the purpose of reducing or avoiding tachycardia or tachyarrhythmias.
Bottom line: Substitution of levalbuterol for albuterol to avert tachycardia in critically ill patients is not warranted.
Citation: Khorfan FM, Smith P, Watt S, Barber KR. Effects of nebulized bronchodilator therapy on heart rate and arrhythmias in critically ill adult patients. Chest. 2011;140:1466-1472.