Authors: Hridesh Chatha, Jo Sutton-Klein, Jamie Miles / Editors: Rajesh Chatha, Robert Hirst / Codes: C3AP1c, CAP22, CMP2, CMP3, HMP3, U5, U8, NepC1, NepP2, RP3, RP4, SLO10, SLO6, TP2 / Published: 15/07/2021
Happy TERNSday! The aim of TERN Top Papers is to highlight the top emergency care related papers for emergency physicians, keeping them abreast of the latest practice-changing studies.
This month’s topic is diagnostic imaging. Our team in South Yorkshire narrowed down over 1600 papers to bring you eleven papers. We grouped the papers into four separate areas: echocardiography in life support, POCUS, intravenous contrast and renal function, and imaging in trauma.
Echocardiography in Life Support
Quantitative characterization of left ventricular function during pulseless electrical activity using echocardiography during out-of-hospital cardiac arrest.1
The aim of this study was to assess whether the degree of left ventricular activity as seen on echocardiography was a predictor of outcomes in pulseless electrical activity (PEA) out-of-hospital cardiac arrests (OHCA).
The investigators performed a secondary analysis on data from the REASON trial, which was a prospective cohort study on cardiac echo and cardiac arrest outcomes 2. This analysis included OHCA subjects with PEA as an initial rhythm.
They chose left ventricular fractional shortening (LVSF) as the dependent variable. This can be obtained from a single echo view, and is a fairly simple calculation of the ratio of LV diameter at end-diastole and end-systole.
Although they found no association between LVFS and survival to hospital, they did find a small association between higher LVFS and ROSC: the predicted probability of ROSC was 75% for LVFS between 23.4–96% (fourth quartile) compared to 47% for LVFS between 0–4.7% (first quartile).
An incidental but key finding was that only 29% of the eligible subjects had echocardiography images of good enough quality to measure LVFS. This limited their analytical sample to 84 subjects, and consequently the results of this study are not wildly convincing.
In this study the calculation of LVFS was done retrospectively by investigators – the predictability of bedside calculation of LVFS during a cardiac arrest situation will likely be quite different.
In the future we might be routinely calculating LVFS during PEA-cardiac arrests to predict probability of ROSC, but at present the evidence is not particularly compelling.
- Teran F, Paradis NA, Dean AJ, Delgado MK, Linn KA, Kramer JA et al. Quantitative characterization of left ventricular function during pulseless electrical activity using echocardiography during out-of-hospital cardiac arrest. Resuscitation. 2021 Jun, S0300-9572(21)00200-8. doi:10.1016/j.resuscitation.2021.05.016
- Gaspari R, Weekes A, Adhikari S, Noble VE, Nomura JT, Theodoro D et al. Emergency department point-of-care ultrasound in out-of-hospital and in-ED cardiac arrest. Resuscitation. 2016 Dec; 109:33-39. doi:10.1016/j.resuscitation.2016.09.018
Association of ultrasound-related interruption during cardiopulmonary resuscitation with adult cardiac arrest outcomes: A video-review retrospective study.3
The aim of this study was to investigate whether echocardiography-related interruption during CPR was associated with patient outcomes.
This was a retrospective, single centre study which included adult patients who had received CPR in the ED. They used video recording systems to collect data from cardiac arrest situations. 210 patients were included in the analysis.
They found that the median no-flow time was 99.5s. This was broken down into a median of 26.5s (Q1-Q3: 0.0–59.0 s) for echo-related, and 60.5s (Q1-Q3: 34.0–101.9) for non-echo related interruptions.
Longer echo-related interruptions of 77-122s were associated with increased odds of survival to hospital discharge (OR: 7.31, 95% CI: 1.59–33.59; p-value = 0.01)
While echo during CPR did increase no-flow time, it was associated with better outcomes. Reducing no-flow times should not come at the cost of not performing echocardiography or echo-associated procedures if necessary.
- Chou EH, Wang C, Monfort R, Likourezos A, Wolfshol J, Lu T et al. Association of ultrasound-related interruption during cardiopulmonary resuscitation with adult cardiac arrest outcomes: A video-reviewed retrospective study. Resuscitation 2020 Apr; 149: 74-80. doi:10.1016/j.resuscitation.2020.02.004
Barriers to point-of-care ultrasound utilization during cardiac arrest in the emergency department: a regional survey of emergency physicians.4
The aim of this study was to gain an understanding of barriers faced by physicians to performing echocardiography during cardiac arrest.
They invited 210 attending and resident emergency physicians from three training programs in South Florida to complete a survey. The surveys for attending and resident physicians differed.
Attending physicians were asked to rate 9 pre-determined barriers on a Likert scale. Residents were asked to indicate the presence or absence of 9 pre-determined barriers as binary data, as well as respond to some open-ended questions. The barriers were then ranked.
187 physicians responded. For attending physicians, the top ranked personal barriers were “I do not feel comfortable with my POCUS skills” and “I do not have sufficient time to dedicate to learning”. For residents, the top ranked barriers were “Time to retrieve and operate the machine” and “Chaotic milieu.” I’m sure we can all sympathise with the last one!
Both physicians and attendings ranked ideas about the negative impact of POCUS as low.
The research question would probably be better explored using qualitative research, however the themes that came out of this study may resonate with UK-based EM trainees.
Barriers to POCUS use appear not to stem from physicians doubting its utility. Instead, under-confidence with POCUS skills and practical barriers to operating the machine emerged as key.
- Singh MR, Jackson J, Newberry A, Riopelle C, Tran VH, PoSaw LL. Barriers to point-of-care ultrasound utilization during cardiac arrest in the emergency department: a regional survey of emergency physicians. American Journal of Emergency Medicine. 2021; 41: 28-34. doi:10.1016/j.ajem.2020.12.040
Goal-directed ultrasound protocol in patients with nontraumatic undifferentiated shock in the emergency department: prospective dual centre study.5
The aim of the study was to examine the echoSHOCK protocol to diagnose the cause of shock in ED when compared to routine workup. The echoShock protocol assessed for compressive pericardial effusion (tamponade), right ventricle dilatation and flattening of the septum, left ventricle dimension and systolic function, and indices of hypovolaemia.
The study was a prospective study performed in two emergency department (EDs). All patients >18 with shock (defined as SBP<100 mmHg or more than 40mmHg less than usual SBP with one sign of inadequate tissue perfusion). Trauma patients, patients with DNARCPR, known haemorrhagic or anaphylactic shock were excluded.
The cause of shock provided by the treating physician after routine clinical work up was compared with cause of shock determined by the echoSHOCK protocol. This in turn was compared to the gold standard cause of shock determined by an independent expert panel. A trained local investigator (not the treating physicians) performed the echoShock protocol. The trained local investigator had attended accredited training courses and performed at least 100 cardiac examinations. The primary outcome was the degree of agreements as determined by Kappa coefficients.
85 patients (with a mean age of 73±14) were included. Kappa coefficients between routine strategy and echoSHOCK for the cause of shock with the expert panel were 0.33 (95% CI 0.26-0.4) and 0.88 (95% CI 0.83-0.93), respectively. The degree of confidence in diagnosis and treatment increased from 3.9 (2.1) with routine workup to 9.3 (1.1) with echoSHOCK (p<0.001).
The main limitation was that the local investigator performing scan was not blinded to routine work up. Expert panel findings were also not independent of echo results and therefore could have influenced results. There is a potential degree of selection bias as patients presenting during busy times or out of hours were missed.
Using the echoShock protocol could improve the accuracy of diagnosing shock in those with significant training, although further work may be required.
- Leroux P, Javaudin F, Bastard QL, Lebret Y, Pes P, Arnaudet I et al. Goal-directed ultrasound protocol in patients with nontraumatic undifferentiated shock in the emergency department: prospective dual centre study. European Journal of Emergency Medicine. 2021; 28(4): 306-311. doi:10.1097/MEJ.0000000000000801
Evidence base for point-of-care ultrasound (POCUS) for diagnosis of skull fracture in children: a systematic review and meta-analysis.6
The aim of this study was to examine the current evidence for EM physicians using POCUS to diagnose skull fractures.
The primary outcome was to evaluate the sensitivity, specificity, positive predictive value and negative predictive value of POCUS in identifying skull fractures in children.
A systematic search was performed using Ovid Medline, Cochrane Library, Google Scholar, Web of Science and Embase. Prospective studies reporting skull fractures diagnosed with ultrasound in children younger than 18 years due to blunt head injury were included. Studies that did not confirm the fracture with CT were excluded. The quality of studies was evaluated using the QUADAS-2 tool. Data were extracted from the eligible studies to calculate outcomes such as sensitivity and specificity, and when possible overall outcomes were calculated.
Seven studies were included. All eligible studies included patients for whom the decision to perform a CT scan was made in advance. Overall, the included studies demonstrated low risk of bias or had minor concerns regarding risk of bias. The pooled data (n=925) demonstrated a sensitivity of 91%, specificity of 96%, positive predictive value of 88% and negative predictive value of 97%. In all the studies the scans were performed by emergency physicians or fellows. 4 studies reported 1-hour training focussed on ultrasonography of the skull, while two reported videos or skills workshops.
A high degree of sensitivity and specificity with minimal training has the potential to improve diagnosis of skull fractures in children.
However, given that trauma of this severity would carry a concomitant risk of intracerebral haemorrhage, would an ultrasound alone be performed in this patient demographic?
- Alexandridis G, Verschuuren EW, Rosendaal AV, Kanhai DA. Evidence base for point-of-care ultrasound (POCUS) for diagnosis of skull fractures in children: a systematic review and meta-analysis. Emergency Medicine Journal. 2020 Dec 3; emermed-2020-209887. doi: 10.1136/emermed-2020-209887. Online ahead of print.
Ultrasound-directed reduction of distal radius fracture in adults: a systematic review.7
The aim of the study was to conduct a systematic review of the clinical literature to determine whether ultrasound can be used to improve the reduction of distal radius fractures in adults in the ED.
EMBASE, PubMed/MEDLINE, the Cochrane Central Register of Controlled Trials and ClinicalTrials.gov of the US National Library of Medicine were searched for studies evaluating ultrasound-assisted distal radial fracture reductions in comparison with standard care. The primary outcome of interest was manipulation success rates, defined as the proportion of fracture manipulations resulting in acceptable anatomical alignment, with secondary outcome being subsequent surgical intervention rates in ultrasound and standard care group of patients.
248 studies were screened at title and abstract, and 10 studies were included for a narrative synthesis. The quality of this evidence was limited but suggests ultrasound is accurate in determining distal radius fracture reduction and may improve the quality of reduction compared with standard care. Only one study showed a statistically significant improvement. Three showed a non-statistically significant improvement. One study showed a slightly lower rate. One study showed a 97.5% success rate but had no control and one showed a big improvement on repeat reduction attempts using ultrasound.
However, there was insufficient evidence to determine whether this affects the rate of subsequent surgical intervention or functional outcome.
The main limitations are the significant heterogeneity between the studies in methodology and that the quality of studies were generally weak.
We were drawn to this paper as the potential to improve radial reduction using POCUS has exciting potential given the difficulty in obtaining portable x-ray imaging or fluoroscopy during procedural sedation. However, this review suggests there is insufficient evidence that ultrasound in closed reduction of distal radius fracture benefits the patients.
- Malik H, Appelboam A, Nunns M. Ultrasound-directed reduction of distal radius fractures in adults: a systematic review. Emergency Medicine Journal. 2021 Apr 14, emermed-2020-210464. doi:10.1136/emermed-2020-210464
Point-of-care ultrasound induced changes in management of unselected patients in the emergency department – a prospective single-blinded observational trial.8
POCUS is used to change the management in specific groups of patients in the ED. This aim of this study was to identify the effect on a patient’s clinical management if POCUS was applied to unselected patients – all patients presenting to the ED. The study also aimed to identify predictors of ultrasound changing management.
This study was a blinded observational single centre trial. A basic whole body POCUS protocol (focused cardiac ultrasound, focused lung ultrasound, Focused Assessment with Sonography in Trauma (FAST), and focused abdominal ultrasound examination) was performed in extension to the physical examination. The blinded treating physicians were interviewed about the presumptive diagnosis and plan for the patient. Subsequently, the physicians were unblinded to the POCUS results and asked to choose between five options regarding the benefit from POCUS results.
A total of 403 patients were enrolled in this study. The treating physicians regarded POCUS examinations influence on the diagnostic workup or treatment as following: no new information: 249 (61.8%), no further action: 45 (11.2%), further diagnostic workup needed: 52 (12.9%), presumptive diagnosis confirmed 38 (9.4%), and immediate treatment needed: 19 (4.7%).
Predictors of ultrasound being beneficial were a high triage category, patient comorbidities (cardiac disease, hypertension or lung disease) and patients presenting with abdominal pain, dyspnoea, or syncope.
The main limitation of the study was that all examinations were performed by an experienced principal investigator, which reduces external validity.
While this study does show that the majority of patients presenting to the ED do not necessarily benefit from POCUS, it does identify a significant number of all patients presenting to the ED who would benefit from this. Practice and training are needed to achieve reproducible results.
- Weile J, Frederiksen CA, Laursen CB, Graumann O, Sloth E, Kirkegaard H. Point-of-care ultrasound induced changes in management of unselected patients in the emergency department – a prospective single-blinded observational trial. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. 2020; 28: 47. doi:10.1186/s13049-020-00740-x
Intravenous contrast and renal function
Utility of measuring serum creatinine to detect renal compromise in ED patients receiving IV contrast CT scan.9
The aim of this study was to examine the efficacy of a number of discrete clinical factors for identifying risk for renal insufficiency in ED patients requiring intravenous contrast-enhanced CT scan (IVCE-CT) and to help mitigate the risk for developing contrast-induced nephropathy (CIN).
A review was conducted of consecutive ED patients who received IVCE-CT during a 4-month period in a single ED. The values of ED serum creatinine (SCr) performed were tabulated. The medical records of all patients with an elevated SCr (>1.4 mg/dL) were reviewed to determine and correlate the presence of clinical risk factors for underlying renal insufficiency.
During the 4-month study period, there were 2260 consecutive cases who received IVCE-CT; of these, 2250 (99.6%) had concomitant measurement of SCr. Elevated SCr occurred in 141 patients (6.2%) and 75 had a SCr>2 mg/dL (3.3%). 139/141 (98.6%) with an elevated SCr had an underlying chronic or acute medical condition (identified by medical record review) which potentially compromised renal function which included chronic renal disease, diabetes mellitus, HIV infection, cancer, hypertension, congestive heart failure, sepsis/septic shock, chronic alcoholism, and sickle cell disease. Two patients with no identified risk factor each had (mildly) elevated SCr; both had a normal SCr measured post-CT scan. The total cost of performing serum basic metabolic panel to measure SCr in all patients during the 4-month study period was $94,500.
The main limitation of this study is that this is USA based study. A UK based study would be needed to ensure findings are generalisable to the UK population.
The study shows that routine measurement of renal function for imaging may be unnecessary in patients at low risk of renal dysfunction. Development of a risk stratification pathway could reduce the number of tests needed and speed time to scan. However, given that these are tests are usually a part of routine patient work-up for patients presenting to the ED they will likely be obtained despite the need for CT, although might suggest we do not need to wait for this result in this some patients.
- Bonadio W, Molyneux K, Lavine E, Jackson K, Kagen A, Legome E. Utility of measuring serum creatinine to detect renal compromise in ED patients receiving IV contrast-enhanced CT scan. Emergency Radiology. 2021; 10.1007/s10140-021-01942-1. Online ahead of print. doi:10.1007/s10140-021-01942-1
Acute kidney injury after CT in emergency patients with chronic kidney disease: a propensity score-matched analysis.10
This study evaluated AKI incidence among ED patients with pre-existing chronic kidney disease (CKD) undergoing CT exams.
This study was a retrospective cohort study of ED patients diagnosed with CKD stages 3-5 undergoing CT exams with or without intravenous contrast. It applied propensity score matching and then applied multivariable regression adjustment for post-CT ED disposition and ED diagnosis to calculate the adjusted risk of AKI. Secondary patient-centred outcomes included 30-day mortality, end-stage renal disease (ESRD) diagnosis, and dialysis initiation.
Among 103,573 eligible ED patients undergoing CT, propensity score matching yielded 5,589 pairs. Adjusted risk ratio (ARR) for AKI was higher overall for contrast-enhanced CT (1.60; 95% CI 1.43-1.79). However, secondary outcomes were infrequent: 19/5,589 non-contrast vs. 40/5,589 contrast required dialysis within 30 days (adjusted risk 0.3% vs 0.7%; adjusted risk reduction 0.4%; 95% CI 0.1%-0.7%). Mortality was 8.5% in the non-contrast group and 7.1% in the contrast group.
The main limitation of the study was that the prevalence of CKD 4-5 was low and consequently the study lacked power in this group. In addition, it was a retrospective study subject to the usual potential biases.
This study showed that even in patients receiving contrast with known CKD the risk of patient centred outcome was low despite a high risk of AKI.
- Kene M, Arasu VA, Mahapatra AK, Huang J, Reed M. Acute Kidney Injury After CT in Emergency Patients with Chronic Kidney Disease: A Propensity Score-matched Analysis. Western Journal of Emergency Medicine. 2021; 22(3): 614-622. doi:10.5811/westjem.2021.1.50246
Imaging in trauma
Does Prehospital spinal immobilization influence in-hospital decision to obtain imaging after trauma?11
The aim of the study was to determine whether patients presenting with a cervical collar were more likely to undergo spinal imaging that those who arrived at the ED without a collar.
This was a retrospective cohort study which included all adult trauma patients presenting to a level 1 trauma center over a four-month period. 1,438 patients were stratified by acuity (categorised 1-3 based on presumed severity of injury), mechanism, and having a known injury above the clavicles on examination (defined as pain, wounds, or hematomas). Cervical spine imaging findings were recorded and patients were followed up for two years to ensure there were no missed injuries.
75% percent of all patients arrived to the ED with a cervical collar in place. 975 patients (67.8%) had a CT of their cervical spine. Those with a cervical collar in place received a cervical CT scan 80% of the time, while those arriving without a cervical collar received a cervical scan 30.6% of the time (p <.0001). None of the patients who received no imaging had a delayed or missed fracture. Category 2 and 3 patients (with and without signs of injury above the clavicle) sustaining low energy falls or those in motor vehicle collisions with collars were more likely to receive a CT of their cervical spine.
35 (2.43%) patients sustained cervical spine injury, with 26 (1.81%) of these being clinically significant. No conscious patients without complaints proximal to the clavicles had cervical injury.
The main limitations of these findings was that it was a retrospective review, and it was also performed in the USA. Practice for the use of collars may differ which means findings may not be generalizable to the UK.
This study demonstrated that patients with a pre-hospital cervical collar fitted by ambulance crew were more likely to be imaged. The study emphasised the importance of reassessing a patient at arrival to ED. In addition, the study indicated that patients without signs of injuries above the clavicle were very unlikely to have cervical spine fracture, although the study was not powered to examine this.
- Drain J, Wilson ES, Moore TA, Vallier HA. Does prehospital spinal immobilization influence in hospital decision to obtain imaging after trauma? Injury. 2020; 51(4): 935-941. doi:10.1016/j.injury.2020.02.097
Screening performance of the chest x-ray in adult blunt trauma evaluation: Is it effective and what does it miss?12
The aim of this study was to assess the use of chest x-ray as a screening tool for thoracic injury in adult blunt trauma assessment.
This study was a sub-analysis of the NEXUS chest CT study which was a prospective cohort study of blunt trauma patients >14 years of age who received chest imaging as part of their evaluation across nine trauma centres.13 4501/11477 (39.2%) of patients from the original study had both a chest x-ray and CT chest.
1496 (33.2%) were found to have an injury, of which 256 (17%) were classified as major injury. CXR missed injuries in 818 patients (54.7%), of which 63 (7.7%) were classified as major injuries.
For injuries of major clinical significance, CXR had a sensitivity of 75.4% (95% CI 69.6–80.4%), specificity of 86.2% (95% CI 85.1–87.2%),negative likelihood ratio of 0.3 (95% CI 0.2-0.4), and positive likelihood ratio of 5.5 (95% CI 4.9 – 6.0).
For any injury CXR had a sensitivity of 45.3% (95% CI 42.8–47.9%), specificity of 96.6% (95% CI 95.9–97.2%), negative likelihood ratio of 0.3 (95% CI 0.2-0.4), and positive likelihood ratio of 24.7 (95%CI 22.9 – 26.7)
The most common missed major injuries were pneumothorax (30/185; 16.2%), spinal fractures (19/39; 48.7%), and haemothorax (8/70; 11.4%). The most common missed minor injuries were rib fractures (381/836; 45.6%), pulmonary contusion (203/462; 43.9%), and sternal fractures (153/229; 66.8%).
The main limitations of the study was possible selection bias, as patients were included only if they had a chest X-ray and CT, and these patients may have had a chest X-ray because the treating physician perceived them to have been at lower risk of chest injury.
A positive chest x-ray is a good predictor of chest injury but a negative chest does not exclude injury. However, in combination with other NEXUS chest predictors (rapid deceleration mechanism, distracting injury, chest wall tenderness, chest pain, age > 60, altered mental status, and intoxication) chest x-ray may be used to assist in screening for chest injuries, although with judicious patient selection.
- Dillon DG, Rodriguez RM. Screening performance of the chest X-ray in adult blunt trauma evaluation: Is it effective and what does it miss? American Journal of Emergency Medicine. 2021; 49: 310-314. doi:10.1016/j.ajem.2021.06.034
- Rodriguez RM, Hendey GW, Mower W, Kea B, Fortman J, Merchant G et al. Derivation of a decision instrument for selective chest radiography in blunt trauma. Journal of Trauma. 2011; 71(3): 549-53. doi:10.1097/TA.0b013e3181f2ac9d.