Early Predictors of Outcome in Comatose Survivors of Ventricular Fibrillation and Non-ventricular Fibrillation Cardiac Arrest Treated with Hypothermia: A Prospective Study

The Journal of Emergency Medicine with NSTEMI and 20,233 patients with STEMI from a prospective registry. There were 455 patients with NSTEMI who presented with RBBB, and 894 patients with STEMI presented with RBBB. At baseline, patients who presented with RBBB with either STEMI or NSTEMI were older, more likely to have suffered a prior myocardial infarction or have renal failure, and more often presented with tachycardia or in cardiogenic shock. In STEMI patients, those with RBBB compared to those without more often had anterior wall MI, higher peak enzyme levels, and lower left ventricular ejection fraction, whereas the same trends were not true for NSTEMI patients. In both STEMI and NSTEMI, patients with RBBB less often received short-term reperfusion treatment as well as specific medical therapy. RBBB was associated with an increase in in-hospital death rate in both NSTEMI and STEMI and an increase in all-cause mortality after discharge in STEMI patients only. In their discussion, the authors point out the association of RBBB and less aggressive treatment, and the higher incidence of in-hospital and long-term mortality in STEMI patients. They also suggest that RBBB may be an indicator of a larger infarction area compared to similar patients without RBBB. [Michael Prendergast, MD, Denver Health Medical Center, Denver, CO] Comments: Although the authors do not explain how they excluded left bundle branch block patients in their final analysis while including them in their definition of STEMI, this study does provide important data on a common emergency department finding. The additional risk of RBBB in patients with acute myocardial infarction, especially STEMI patients, should raise concerns for patients with RBBB seen in the emergency setting.

e THE USE OF LEUKOREDUCED RED BLOOD CELL PRODUCTS IS ASSOCIATED WITH FEWER INFECTIOUS COMPLICATIONS IN TRAUMA PATIENTS. Randal SF, Sperry JL, Phelan HA, et al. Am J Surg 2008;196:56 – 61. Prior clinical studies suggest that blood-component resuscitation may lead to deleterious immune modulation with an associated increased risk of bacterial infection and possible increased mortality. However, these studies included few trauma patients, a population often requiring large amounts of transfusion products. This retrospective observational study from an urban level 1 trauma center was designed to determine whether transfusion of leukoreduced red blood cell (RBC) products have an effect on infectious complications in a trauma population. There were 240 patients enrolled in the leukoreduction group from March 2002 through December 2003; 438 patients enrolled between March 2000 and December 2001 served as a historical control group. Multivariate logistic regression controlling for age, sex, injury severity, and number of transfusions was used to determine whether the use of leukoreduced RBC products was an independent predictor of infectious complications. In those patients receiving leukoreduced RBC products, a 45% reduction in nosocomial pneumonia (odds ratio [OR] .55; 95% confidence interval [CI] .33–.91) was observed. A 52% reduction in any type of infection was also noted (OR .48, 95% CI .31–.73). Subset analysis of a group receiving massive transfusion, defined as ⬎ 6 units of RBC product in 24 h, resulted in 67% reduction of any type of

99 infection (OR .33, 95% CI .15–.73). The authors conclude that pre-storage leukoreduction of RBCs is associated with a decreased infection rate in a trauma population. This protective effect may be even more pronounced in those receiving massive transfusion. [Chris Davis, MD, Denver Health Medical Center, Denver, CO] Comment: Although the authors observe a decreased infection rate in those receiving leukoreduced blood products, it is important to note there is no associated mortality benefit. Furthermore, the use of historical controls instead of a prospective randomized design also clouds the validity of the results.

e EARLY PREDICTORS OF OUTCOME IN COMATOSE SURVIVORS OF VENTRICULAR FIBRILLATION AND NON-VENTRICULAR FIBRILLATION CARDIAC ARREST TREATED WITH HYPOTHERMIA: A PROSPECTIVE STUDY. Oddo M, Ribordy V, Feihl F, et al. Crit Care Med 2008;36:2296 –301. This study sought to determine if therapeutic hypothermia (TH) is appropriate therapy for patients with cardiac arrest (CA) regardless of initial arrest rhythm or presence of postresuscitation shock. Between December 2004 and October 2006, all post-CA patients with persistent coma admitted to the intensive care unit at an academic hospital in Switzerland were evaluated. Patients were externally cooled to a core temperature of 33 ⫾ 1°C. All received intra-arterial and pulmonary-artery catheters. Crystalloid resuscitation, norepinephrine, and dobutamine were administered to maintain a mean arterial pressure (MAP) ⬎ 70 mm Hg, SvO2 ⬎ 65%, and arterial blood lactate ⬍ 2.5 mmol/L. Patients with acute ST elevation myocardial infarction underwent angioplasty and percutaneous coronary intervention once cooling was initiated. Of 88 total patients, 14 were excluded due to age ⬎ 80 years (n ⫽ 11) or underlying terminal disease (n ⫽ 3). Among the final cohort (n ⫽ 74), 34 (46%) met criteria for shock (MAP ⬍ 60 or systolic blood pressure ⬍ 90 mm Hg requiring pressor support after resuscitation). Of the 39% (n ⫽ 29) surviving, 24 had a “good neurologic outcome” (full recovery or only moderate disability). Survivors had lower times to restoration of spontaneous circulation (ROSC) (median 15.5, interquartile range [IQR] 10 –21 min vs. 32, IQR 25–39 min, p ⬍ 0.0001) and lower initial lactate levels (median 8.1, IQR 4.7–10 mmol/L vs. 11, IQR 7.9 –14 mmol/L, p ⫽ 0.0008). No good neurologic outcome occurred in patients with time to ROSC ⬎ 25 min. Only time to ROSC (odds ratio [OR] 45.10, confidence interval [CI] 4.64 – 408.60, p ⬍ 0.001) and plasma lactate levels (OR 0.79, CI 0.64 – 0.97, p ⫽ 0.02) were associated with survival. In a separate analysis, the authors pooled data from this and a previous study including historical controls not treated with TH. The authors note that TH was associated with an improvement in neurologic outcomes among those with ROSC ⱕ 25 min (19/28, 68% vs. 7/33, 21%; no p-value provided). The authors conclude that both time to ROSC and initial lactate are important predictors of survival in CA treated with TH, and that these data suggest a group of patients with “reversible” anoxic

100 injury who are more likely to improve with TH. Second, they suggest use of TH regardless of the presence of post-resuscitation shock. [John E. Houghland, MD, Denver Health Medical Center, Denver, CO] Comment: This prospective study adds to the growing body of evidence that time from collapse to ROSC is associated with outcomes, regardless of the presence of post-resuscitation shock. The study is limited by its modest population size, and further investigation into the role of TH in non-ventricular fibrillation CA is necessary. Use of historical controls is a significant limitation of the authors’ further analysis, and the conclusions made based on these data are more problematic because no information is presented regarding the population characteristics or the resuscitative and other medical therapy these patients received.

e NOCTURIA IN MEN LESS THAN 50 YEARS OF AGE MAY BE ASSOCIATED WITH OBSTRUCTIVE SLEEP APNEA SYNDROME. Moriyama Y, Miwa K, Tanaka H, Fujihiro S, Nishino Y, Deguchi T. Urology 2008;71:1096 – 8. This study assessed the prevalence of nocturia in patients with obstructive sleep apnea syndrome and evaluates additional voiding disorder symptoms. The authors analyzed data from 73 patients to compare the Apnea-Hypopnea index score (AHI), voiding score, number of voids per night, and age. The prevalence of nocturia in this study was 41.1%. The AHI score was higher in patients with nocturia, especially among patients ⬍ 50 years of age, whereas patients aged ⬎ 50 years had no significant difference. In patients over 50, the voiding symptom score was significantly higher in patients with nocturia compared to those without nocturia. The authors note that their study suggests that in older patients, nocturia is primarily associated with voiding symptoms, whereas in younger patients there may be more association with obstructive sleep apnea symptoms. [Michael Prendergast, MD, Denver Health Medical Center, Denver, CO] Comments: This small study points out an important association between obstructive sleep apnea syndrome and urologic disease. Although less germane to the emergency setting, it may offer the emergency physician additional insight into primary disease processes in patients with complaints of nocturia or voiding abnormalities. Additional studies may be needed to explain the difference in associated symptoms between older and younger patients.

e EVALUATION OF A “TRIPLE RULE-OUT” CORONARY COMPUTED TOMOGRAPHY (CT) ANGIOGRAPHY PROTOCOL: USE OF 64-SECTION CT IN LOWTO-MODERATE RISK EMERGENCY DEPARTMENT PATIENTS SUSPECTED OF HAVING ACUTE CORONARY SYNDROME. Takakuwa KM, Halpern EJ. Radiology 2008;248:438 – 46. Chest pain is a common yet complex diagnostic challenge for the emergency physician. An estimated 6 – 8 billion dollars

Abstracts is spent each year on negative inpatient cardiac evaluations. This prospective single-center cohort study used computed tomographic (CT) angiographic “triple rule-out” to evaluate 201 patients stratified as having low-to-moderate risk of acute coronary syndrome (ACS) by thrombolysis in myocardial infarction scoring. A triple rule-out protocol allowed for accurate identification of coronary disease, pulmonary embolism, aortic dissection or other thoracic disease. A disease process other than coronary atherosclerosis explained the presenting symptoms in 11% of this population. Clinically important noncoronary diagnoses that could not explain a patient’s presenting symptoms were identified in an additional 14% of patients. Eleven percent of this cohort had moderate to severe coronary disease requiring further imaging or inpatient workup as determined by an emergency physician or cardiologist. Seventy-six percent of those patients with no more than mild coronary disease were discharged home or treated without further diagnostic imaging. At 30-day follow-up, the negative predictive value of coronary CT angiography for ACS was 99.4% in this patient population. No adverse outcomes were reported at 30 days. The authors conclude that triple rule-out CT angiography allows for safe and accurate disposition of a population with low-to-moderate risk for ACS. Coronary CT angiography precluded additional cardiac testing in the majority of patients and may represent a more timely and cost-effective strategy for risk-stratifying this patient population. [Chris Davis, MD, Denver Health Medical Center, Denver, CO] Comment: Although this study represents only a small patient population and included only one interpreting radiologist, it represents an encouraging effort to safely disposition those patients with low-to-moderate risk of ACS, often without further need of diagnostic imaging or hospitalization.

e ISO-OMOLALITY VERSUS LOW-OSMOLALITY IODINATED CONTRAST MEDIUM AT INTRAVENOUS CONTRAST-ENHANCED COMPUTED TOMOGRAPHY: EFFECT ON KIDNEY FUNCTION. Nguyen SA, Suranyi P, Ravenel JH, et al. Radiology 2008;248:97–105. This single-center, randomized, double-blind prospective trial investigated the effects of an iso-osmolality contrast medium compared with a low-osmolality agent on renal function in high-risk patients undergoing intravenous (i.v.) contrastenhanced computed tomography (CT). Patients were adults aged ⱖ 18 years undergoing CT scan with i.v. contrast who had a baseline serum creatinine (SCr) ⱖ 1.5 mg/dL or glomerular filtration rate (GFR) ⬍ 60 mL/min. Exclusion criteria included: pregnancy or lactation, receiving contrast 7 days before study, previous anaphylaxis to contrast, acute renal failure or chronic hemodialysis, heart or renal transplant, or recent use of potentially nephrotoxic medications or nonsteroidal anti-inflammatory medications other than aspirin. Serial measurements of SCr and GFR were recorded at baseline, within 24 h of CT (day 1), and on days 2 and 3. Follow-up occurred at 30 and 90 days to record adverse events. Between September 2004 and July 2006,