2013 - September R3 Journal Review
Perry JJ, Stiell IG, Sililotti ML et al. Clinical Decision Rules to Rule Out Subarachnoid Hemorrhage for Acute Headache. JAMA Sept 25 2013;310(12):1248-55. This was a multicenter cohort study, involving 10 university affiliated hospitals in Canada between 2006-2010. Inclusion criteria included non-traumatic headache that peaked within one hour of onset and NO neurologic deficits. Patients were excluded if they had 3 or more similar headaches over 6 months, return visits for same headache, confirmed subarachnoid transfers, focal neuro deficits, known prior dx of subarachnoid, aneurysms, other intracerebral pathology. Subarachnoid hemorrhage, defined as (1) subarachnoid blood on computed tomography scan; (2) xanthochromia in cerebrospinal fluid; or (3) red blood cells in the final tube of cerebrospinal fluid, with positive angiography was the primary outcome measure.
After patients met criteria, the attendings/residents were approached with a form in which they had to fill out 19 clinical findings. These findings included many of the common signs/sx from prior decision rules or others that the research team thought may be significant. The form did not help them decide whether or not to order imaging/LP, etc. After the diagnosis was made, the research team compared all the signs/symptoms that were common amongst those with and without subarachnoid hemorrhages. The pre-existing decision rules were compared to each other. And finally, the research team extrapolated an all-inclusive decision rule. They found that the pre-existing “decision rule #1” was most sensitive – but when adding 2 more variable, they reached 100% sensitivity (however, naturally sacrificing specificity).
Of the 2131 enrolled patients, 132 (6.2%) had subarachnoid hemorrhage. The decision rule including any of age 40 years or older, neck pain or stiffness, witnessed loss of consciousness, or onset during exertion had 98.5% (95% CI, 94.6%-99.6%) sensitivity and 27.5% (95% CI, 25.6%-29.5%) specificity for subarachnoid hemorrhage. Adding "thunderclap headache" (ie, instantly peaking pain) and "limited neck flexion on examination" resulted in the Ottawa SAH Rule, with 100% (95% CI, 97.2%-100.0%) sensitivity and 15.3% (95% CI, 13.8%-16.9%) specificity.
Overall, this study took 3 existing decision rules that had sensitivities between 95-98% and attempted to improve upon that. By adding two additional signs/sx (thunderclap headache and limited neck flexion on exam), if a patient does NOT have one or more of these, it is unlikely they have a SAH. Limitations to this study include recall bias (if headache peaked within one hour), does not apply as an “acute headache rule”, and no gold standard definition of SAH (especially if it is clinically significant or not).
In the ED setting were headaches are extremely common, this study will be useful in identifying those who are LOW risk (ie those who do not display ANY high risk signs/sx).
The Ottawa SAH Rule: For alert patients older than 15 y with severe, nontraumatic headache reaching maximum intensity within one hour. Investigate if one or more high risk variables are present:
1. age 40 y or more
2. neck pain or stiffness
3. witnessed LOC
4. onset during exertion
5. thunderclap headache
6. limited neck flexion on exam
Yeatts D, Dutton R, Hu P, et al. Effect of Video Laryngoscopy on Trauma Patient Survival: A Randomized Controlled Trial. J Trauma Acute Care Surg. 2013 July. 75(2) 212-219. This was a single center, randomized controlled, prospective trial looking at direct laryngoscopy versus video laryngoscopy (specifically with the Glidescope) in emergency airway management of trauma patients. Of the 898 meeting study criteria, a total of 623 patients were enrolled from July 2008 through May 2010, 320 randomized to direct and 303 randomized to video. Groups were well matched without significant difference. The primary outcome was survival to hospital discharge. Secondary outcomes were intubation duration and first-pass success rate.
Primary outcome: 93% of the direct laryngoscopy group survived until hospital discharge, versus 91% of the video laryngoscopy group, with no significant difference (p=0.43).
Secondary outcomes: No statistically significant different between first pass success rate between groups, 81% for direct and 80% for video (p=0.46). There was a statistically significant difference in median intubation attempt duration (p<0.001) between the groups, 40 seconds for direct laryngscopy versus 56 seconds for video laryngoscopy. This remained true across all intubating skill levels.
Finally the authors concluded using post hoc analysis that mortality was higher severe head injured patients in video laryngoscopy (22/73, 30%) versus direct laryngoscopy (16/112, 14%), (p=0.047). They hypothesized this may be related to greater exposure to hypoxia stemming from intubation time.
This study concluded that there is no survival benefit to video laryngoscopy in emergency airway management of trauma patients. However, there are limitations. The authors admit to a high degree of study noncompliance among providers. Additionally, multiple patients were excluded from the study because there were perceived to be “difficult” intubations from the start – in all cases video laryngoscopy was used. Overall, one can conclude from this study that there is no survival benefit to video laryngoscopy in routine trauma airway management.
Meltzer AC, Baumann BM, Chen EH, et al. Poor Sensitivity of a Modified Alvarado Score in Adults With Suspected Appendicitis. Ann Emerg Med. 2013; 62: 126-131. Article describes a prospective observational study to evaluate the use of a clinical decision rule, the Modified Alvarado Score, to identify patients at low risk for appendicitis in order to reduce reliance on abdominal computed tomography for diagnosis. The study was set at two large, urban tertiary care, referral, university hospital Emergency Departments, and included adults aged 18 years or older who were determined by attending or resident evaluation to have appendicitis as one of top three likely diagnoses. Eligible patients included those with nontraumatic abdominal pain of less than 72 hours, and excluded those who were pregnant, suffered abdominal trauma, or had underwent abdominal surgery in the previous week. A total of 261 patients (68% female, 52% white, mean age 35 [ages 18-89]) out of an initial 41,000 patients presenting to either ED in a one-year period were scored according to symptoms, clinical signs and presence of leukocytosis. The primary aim of the study was whether a low Modified Alvarado Score, <4, would be able to exclude acute appendicitis as a diagnosis when suspected according to physician clinical judgment. A final diagnosis was made either at ED discharge with ordered imaging, at 7-day follow-up if no imaging ordered in ED, or at hospital discharge if admitted according to CT imaging and relevant surgical pathology. The Sensitivity/Specificity of the Modified Alvarado Score was 72% [95% CI 58%-84%]/54% [95% CI 47%-61%]. Physician clinical judgment that appendicitis was most or second most likely diagnosis demonstrated sensitivity/specificity of 93% [95% CI 82%-98%]/33% [95% CI 27%-40%]. The study concluded that a low Modified Alvarado Score was less sensitive than physician clinical judgment in excluding acute appendicitis. It should be noted, however, that 10 patients who were not enrolled did have acute appendicitis as their final diagnosis. Physicians should continue to rely on clinical judgment and an evolving ED course to guide their use of CT abdominal imaging rather than a Modified Alvarado Score < 4. Certainly, discrepancy in physician clinical judgment was likely as interns, as well as attendings were responsible for enrollment of subjects. It is not clear who, per training, was responsible for failing to include 10 patients ultimately diagnosed with appendicitis; and thus Modified Alvarado Scores were not calculated in these instances. This being stated, residents with less training than attendings, still demonstrated greater sensitivity when diagnosing appendicitis than did clinical decision rule. As per population applicability, the percentage of Asian patients meeting inclusion criteria appears less than representative than the UCD ED population.