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Emergency Ultrasound

Journal Summary

Emergency department point-of-care ultrasound in out-of-hospital and in-ED cardiac arrest
Review by Michael Boniface, MD

It is commonly acknowledged that survival to discharge in patients with out-of-hospital cardiac arrest is abysmal. Previously, small sample-size observational data has shown that the presence or absence of cardiac activity during cardiac arrest with PEA or asystole can help predict survival, but most of these data were single site and small sample size. Tremendous effort and planning were clearly put into this study which represents the combined effort of dozens of investigators across 20 clinical sites in the United States. Overall, 953 patients presenting with cardiac arrest were enrolled and 793 included in final analysis. Patients were excluded if the arrest was trauma-related, resuscitative efforts lasted less than 5 minutes, if no ACLS meds were given representing non-adherence to study protocol, if resuscitation was not continued after initial ultrasound, or to honor a do-not-resuscitate order. Primary outcome was percentage of patients surviving to hospital admission and secondary outcomes were survival to hospital discharge and ROSC. Multivariate analysis showed that presence of cardiac activity on the initial ultrasound during resuscitation was the variable most associated with survival following arrest, outperforming other variables such as location of arrest, bystander CPR, and amount of epinephrine administered. Primary outcome of survival to hospital admission was 14.4% for all patients but 28.9% for patients with cardiac activity on ultrasound. Only 7.2% of patients without cardiac activity survived to hospital admission. Secondary outcome of survival to discharge was 3.8% vs 0.6% in patients with cardiac activity vs without. Also of note is that when cardiac ultrasound identified an intervenable problem, such as pericardial effusion, survival was higher. Survival to hospital discharge was 15.4% in 13 patients who underwent pericardiocentesis. A journal summary or abstract really cannot do this study justice. I strongly recommend that you read this in its entirety and even propose it for your next journal club.

Gaspari R, Weekes A, Adhikari S, et al. Emergency department point-of-care ultrasound in out-of-hospital and in-ED cardiac arrest. Resuscitation. 2016 Sep 28;109:33-39. doi: 10.1016/j.resuscitation.2016.09.018. [Epub ahead of print]

 

Corrected flow time: a noninvasive ultrasound measure to detect preload reduction by nitroglycerin
Review by Michael Boniface, MD

Realizing that IVC measurement is not the panacea for noninvasive volume assessment we once hoped it would be, recent studies have investigated the use of “corrected flow time” for measurement of preload and cardiac output. This corrected flow time is a Doppler analysis of arterial blood flow, previously measured in the carotid artery. Specifically, it represents the systolic flow time corrected for heart rate. While prior studies have shown an increase in corrected flow time (FTc) with volume administration, this aim of this study was to show a reciprocal relationship with relative preload reduction following administration of a single dose of 0.3mg sublingual nitroglycerin in a prospective cohort of chest pain observation patients who had ruled out for MI by enzymes. Interestingly, the investigators chose the brachial artery rather than the carotid, which had not previously been studied. Fifty-four patients were included in final analysis and sure enough the mean FTc decreased from 339ms to 325ms (p = .0001). Also observed was a statistically significant change in heart rate, although increasing only from a mean of 70bpm to 75bpm. No significant change in blood pressure was observed. The data analysis involved what seem to be some cumbersome manual measurements during image post-processing and this may have affected inter-rater reliability, but with p-values this low it probably doesn’t matter. Keep your eye out for future research into this technique because potential applications in trauma, sepsis, and a variety of other clinical conditions are very intriguing.

Pare JR, Liu R, Moore CL, et al. Corrected flow time: a noninvasive ultrasound measure to detect preload reduction by nitroglycerin. Am J Emerg Med. 2016 Sep;34(9):1859-62. doi: 10.1016/j.ajem.2016.06.077. Epub 2016 Jun 24.

Point-of-care ultrasonography for the management of shoulder dislocation in ED
Review by Tomislav Jelic, MD

Shoulder dislocations account for a large proportion of large joint dislocations that emergency physicians encounter. Standard assessment of the glenohumeral joint (GHJ) involves x-rays however several case reports show that POCUS assessment of the GHJ is feasible. The hypothesis of this study was to evaluate the utility of POCUS assessment in the diagnosis of shoulder dislocations, as compared to plain film x-rays. Secondary outcomes were to assess the ability of POCUS to confirm GHJ reduction and fracture diagnosis.

This was a prospective observational study based out of two hospitals in Turkey. Patients 15 years and older were eligible to be enrolled if their physical exam was concerning for possible GHJ dislocation. Patients were excluded if they were a victim of polytrauma, any associated fractures, less than 15 years of age or could not provide consent. 

8 attending physicians with a considerable amount of POCUS experience (median 7.5 years!) were trained using a 30-minute lecture and 2 hour hands on scanning session. Physicians performing GHJ POCUS were then asked to rate if there was pathology present or not. If there was uncertainty, then this was categorized into the pathology present group. A very detailed description of the scanning protocol is available in the study.

103 patients were enrolled in the study. POCUS diagnosed 98 patients with dislocations, and 5 as normal. This correlated perfectly with x-ray findings, yielding a sensitivity and specificity of 100% and 100%. Shoulder reduction was confirmed in 93/94 patients with POCUS, and one reduction failure. For shoulder fractures, POCUS confirmed 5 fractures, 15 possible fractures and 80 with no fractures seen. Only 3 of the 15 possible fractures had them confirmed on x-ray, the remainders were negative. This yielded a sensitivity of 100% and specificity of 84.2% for diagnosis of fractures with POCUS.

This was overall a well done study. One could argue the limitation of x-ray, but it is widely accepted as the gold standard. This was a convenience sampling of patients and we do not know anything about their body habitus or other factors affecting the ease of scanning. Nor do we know the time it took to perform the scan. Experienced providers did all scans, questioning its generalizability. Enrollment also occurred only if trained POCUS providers were on duty.

In general, this is still an attractive modality to learn and this article supports its accuracy. It is particularly helpful in those patients where you may be unsure if the reduction is successful and the patient is still sedated. In this group, assessing GHJ position with POCUS could save you a re-sedation of your patient if you wait for them to wake up and take an x-ray.

Akyol C, Gungor F, Akyol AJ, et al. Point-of-care ultrasonography for the management of shoulder dislocation in ED. Am J Emerg Med. 2016 May;34(5):866-70. doi: 10.1016/j.ajem.2016.02.006. Epub 2016 Feb 16.



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