Benjamin Bloom

The role of venous blood gas in the emergency department: a systematic review and meta-analysis.

The aim of this study is to provide a systematic review of the literature reporting agreement between arterial and venous pH, partial pressure of carbon dioxide (PCO2), bicarbonate (HCO3−), base excess and lactate; and to perform a meta-analysis of the differences. Medline and Embase searches using Eduserv Athens from 1950 to present were conducted using the terms ‘VBG’, ‘ABG’, ‘arterial’, ‘venous’, ‘blood’, ‘gas’, ‘lactate’, ‘emergency’ and ‘department’. References of the published papers were hand searched and full-text versions of those deemed helpful to the question were obtained. Mean difference (MD) and 95% limits of agreement (LOA) were either reported or calculated from the published data. Pooled MDs with 95% confidence intervals (CIs) were calculated for differences between arterial and venous pH, PCO2, bicarbonate and lactate. Thirteen articles relevant to pH, 12 relevant to PCO2, 10 relevant to bicarbonate and three relevant to lactate were found. The pooled MD (venous−arterial) for pH was −0.033 pH units (95% CI −0.039 to 0.027) with narrow 95% LOA, the pooled MD for PCO2 was 4.41 mmHg (95% CI 2.55–6.27) with 95% LOA ranging from −20.4 to 25.8 mmHg, the pooled MD for bicarbonate was 1.03 mmol/l (95% CI 0.56–1.50) with 95% LOA ranging from −7.1 to 10.0 mmol/l and the pooled MD for lactate was 0.25 mmol/l (95% CI 0.15–0.35) with 95% LOA ranging from −2.0 to 2.3 mmol/l. Venous and arterial pH and bicarbonate agree reasonably at all values, but the agreement is highest at normal values. Arteriovenous agreement for PCO2 is poor and PvCO2 cannot be relied upon as an absolute representation of PaCO2. However, normal peripheral PvCO2 has a good negative predictive value for normal arterial PCO2, and a normal PvCO2 can be used as a screen to exclude hypercapnic respiratory disease. There may be a poor agreement between arterial and venous lactate at abnormal values; however, if the venous lactate is normal, it is likely the arterial values of this parameter will also be normal.

A comparison of measurements of sodium, potassium, haemoglobin and creatinine between an Emergency Department-based point-of-care machine and the hospital laboratory.

Blood gas analysers provide electrolyte and metabolic data. In the author’s institution, these values were not used clinically because of the risk of inaccuracy. To discover whether this approach was warranted, we compared values from our Radiometer point-of-care (POC) analyser and the laboratory. A total of 207 patients from an urban Emergency Department received venepuncture for sodium, potassium, creatinine and haemoglobin. Two samples were drawn; one analysed in the laboratory, the other on the POC machine. The results were: sodium: n=182, mean difference (MD) (lab−POC) 3.36, 95% limits of agreement (LOA) 0.18–6.54; potassium: n=171, MD 0.46, 95% LOA −0.12 to 1.03; creatinine: n=183, MD 1.6, 95% LOA −16.2 to 18.7; haemoglobin: n=191, MD −0.29, 95% LOA −1.71 to 1.12. Thus, sodium and potassium showed negative bias on the Radiometer compared with the laboratory. Creatinine and haemoglobin agreed well. We advocate the clinical use of POC values when taken in clinical context.

The agreement between abnormal venous lactate and arterial lactate in the ED: a retrospective chart review.

INTRODUCTION The evidence for prognostication using lactate is often based on arterial lactate (AL). Arterial sampling is painful and difficult, and carries risks. Studies comparing peripheral venous lactate (PVL) with AL showed little difference but predominantly included patients with normal lactate. The objective of this study was to measure agreement between PVL and AL in patients with elevated venous lactate. METHODS This is a retrospective cross-sectional study. INCLUSION CRITERIA ED patients age≥16, attending from October 2010 to June 2011 inclusive, with PVL≥2.0 mmol/L and AL taken within 1 hour. EXCLUSION CRITERIA intravenous fluid prior to or between initial venous and arterial sampling. Primary endpoint: agreement between PVL and AL defined as mean difference±95% limits of agreement (LOA). The misclassification rate was assessed. RESULTS N=232. VL median 3.50 mmol/L, range 2.00 to 15.00 mmol/L. AL median 2.45 mmol/L, range 1.0 to 13.2 mmol/L. The mean difference±SD between PVL and AL for all patients was 1.06±1.30 mmol/L (95%LOA -1.53 to 3.66 mmol/L). Using a cut-off of 2 mmol/L and 4 mmol/L, 36.2% and 17.9% of patients respectively were incorrectly classified as having elevated lactate. CONCLUSION We report greater bias between VL and AL with broader LOA than previously documented. This may partly be due to the fact that we studied only patients with abnormal venous values, for whom close agreement would confer greatest clinical significance. The agreement between abnormal PVL and AL is poor and the high rate of misclassification may suggest that PVL is not a good substitute for AL if the venous lactate is abnormal.

Predictive value of S100-B and copeptin for outcomes following seizure: the BISTRO International Cohort Study.

Objective To evaluate the performance of S100-B protein and copeptin, in addition to clinical variables, in predicting outcomes of patients attending the emergency department (ED) following a seizure. Methods We prospectively included adult patients presented with an acute seizure, in four EDs in France and the United Kingdom. Participants were followed up for 28 days. The primary endpoint was a composite of seizure recurrence, all-cause mortality, hospitalization or rehospitalisation, or return visit in the ED within seven days. Results Among the 389 participants included in the analysis, 156 (40%) experienced the primary endpoint within seven days and 195 (54%) at 28 days. Mean levels of both S100-B (0.11 μg/l [95% CI 0.07–0.20] vs 0.09 μg/l [0.07–0.14]) and copeptin (23 pmol/l [9–104] vs 17 pmol/l [8–43]) were higher in participants meeting the primary endpoint. However, both biomarkers were poorly predictive of the primary outcome with a respective area under the receiving operator characteristic curve of 0.57 [0.51–0.64] and 0.59 [0.54–0.64]. Multivariable logistic regression analysis identified higher age (odds ratio [OR] 1.3 per decade [1.1–1.5]), provoked seizure (OR 4.93 [2.5–9.8]), complex partial seizure (OR 4.09 [1.8–9.1]) and first seizure (OR 1.83 [1.1–3.0]) as independent predictors of the primary outcome. A second regression analysis including the biomarkers showed no additional predictive benefit (S100-B OR 3.89 [0.80–18.9] copeptin OR 1 [1.00–1.00]). Conclusion The plasma biomarkers S100-B and copeptin did not improve prediction of poor outcome following seizure. Higher age, a first seizure, a provoked seizure and a partial complex seizure are independently associated with adverse outcomes.

Risk factors for admission at three urban emergency departments in England: a cross-sectional analysis of attendances over 1 month

Objective To investigate factors associated with unscheduled admission following presentation to emergency departments (EDs) at three hospitals in England. Design and setting Cross-sectional analysis of attendance data for patients from three urban EDs in England: a large teaching hospital and major trauma centre (site 1) and two district general hospitals (sites 2 and 3). Variables included patient age, gender, ethnicity, deprivation score, arrival date and time, arrival by ambulance or otherwise, a variety of ED workload measures, inpatient bed occupancy rates and admission outcome. Coding inconsistencies in routine ED data used for this study meant that diagnosis could not be included. Outcome measure The primary outcome for the study was unscheduled admission. Participants All adults aged 16 and older attending the three inner London EDs in December 2013. Data on 19 734 unique patient attendances were gathered. Results Outcome data were available for 19 721 attendances (>99%), of whom 6263 (32%) were admitted to hospital. Site 1 was set as the baseline site for analysis of admission risk. Risk of admission was significantly greater at sites 2 and 3 (adjusted OR (AOR) relative to site 1 for site 2 was 1.89, 95% CI 1.74 to 2.05, p<0.001) and for patients of black or black British ethnicity (AOR 1.29, 1.16 to 1.44, p<0.001). Deprivation was strongly associated with admission. Analysis of departmental and hospital-wide workload pressures gave conflicting results, but proximity to the “4-hour target” (a rule that limits patient stays in EDs to 4 hours in the National Health Service in England) emerged as a strong driver for admission in this analysis (AOR 3.61, 95% CI 3.30 to 3.95, p<0.001). Conclusion This study found statistically significant variations in odds of admission between hospital sites when adjusting for various patient demographic and presentation factors, suggesting important variations in ED-level and clinician-level behaviour relating to admission decisions. The 4-hour target is a strong driver for emergency admission.

Temporal trends in nitrate utilization for acute heart failure in elderly emergency patients: A single-centre observational study.

BACKGROUND We previously conducted a pilot study that reported the safety of isosorbide dinitrate boluses for elderly emergency patients with acute heart failure syndrome. AIMS To assess the temporal trend in the rate of elderly patients treated with isosorbide dinitrate, and to evaluate subsequent outcome differences. METHODS This was a single-centre study. We compared patients aged>75 years who attended the emergency department with a primary diagnosis of acute pulmonary oedema in the years 2007 and 2014. The primary endpoint was the rate of patients who received isosorbide dinitrate boluses in the emergency department. Secondary endpoints included in-hospital mortality, need for intensive care and length of stay. RESULTS We analysed 368 charts, 232 from patients included in 2014 (63%) and 136 in 2007 (37%). The mean age was 85±6 years in both groups. There was a significant rise in the rate of patients treated with isosorbide dinitrate between 2007 and 2014: 97 patients (42%) in 2014 vs. 24 patients (18%) in 2007 (P<0.01). Comparing the two periods, we report similar in-hospital mortality rates (8% vs. 11%; P=0.5), rates of admission to the intensive care unit (13% vs. 17%; P=0.3) and lengths of stay (10 days in both groups). CONCLUSION We observed a significant rise in the rate of elderly patients treated with isosorbide dinitrate boluses for acute heart failure. However, we did not observe any significant improvement in outcomes.

Short-stay admissions at an inner city hospital: a cross-sectional analysis

Objective To investigate factors predictive of short hospital admissions and appropriate placement to inpatient versus clinical decision units (CDUs). Method This is a retrospective analysis of attendance and discharge data from an inner-city ED in England for December 2013. The primary outcome was admission for less than 48 hours either to an inpatient unit or CDU. Variables included: age, gender, ethnicity, deprivation score, arrival date and time, arrival method, admission outcome and discharge diagnosis. Analysis was performed by cross-tabulation followed by binary logistic regression in three models using the outcome measures above and seeking to identify factors associated with short-stay admission. Results There were 2119 (24%) admissions during the study period and 458 were admitted for less than 24 hours. Those who were admitted in the middle of the week or with ambulatory care sensitive conditions (ACSCs) were significantly more likely to experience short-stays. Older patients and those who arrived by ambulance were significantly more likely to have a longer hospital stay. There was no association of length of inpatient stay with being admitted in the last 10 min of a 4 hours ED stay. Conclusion Only a few factors were independently predictive of short stays. Patients with ACSCs were more likely to have short stays, regardless of whether they were admitted to CDU or an inpatient ward. This may be a group of patients that could be targeted for dedicated outpatient management pathways or CDU if they need admission.

Short-term neurocognitive and symptomatic outcomes following mild traumatic brain injury: A prospective multi-centre observational cohort study

ABSTRACT Objective: To determine the short-term cognitive and symptomatic outcome following mild traumatic brain injury. Methods: Setting: Emergency Departments of two UK tertiary referral hospitals. Participants: Adult patients presenting to the Emergency Departments of the Royal London Hospital and Salford Royal Hospital with suspected traumatic brain injury within 24 hours and Glasgow Coma Score > 8. A non-TBI comparison group included adult patients with no head or neck injury. Design: Prospective multi-centre cohort study. Main measures: The Standardized Assessment of Concussion (SAC), the Concussion Symptom Inventory (CSI) and total number of symptoms, measured at baseline and 72 hours. Results: This study enrolled 189 patients with and 51 patients without TBI. Patients with TBI had marked cognitive impairment which persisted at 72 hours (SAC score at baseline = 25 [23–27] vs 72 hours = 25 [22–27]; p = 0.1). Patients with TBI had persistent high symptom severity, although this had decreased at 72 hours (CSI score at baseline = 9 [4–22] vs 72 hours = 5 [1–19], p = 0.002). A similar pattern was observed with the total number of symptoms (baseline = 4 [2–8] vs 72 hours = 0 [0–4]; p < 0.001). Patients with TBI had worse neurocognitive function, higher overall symptom severity and higher total number of symptoms compared with patients without TBI. Patients without TBI’ neurocognitive function and symptom severity remained constant, but the number of symptoms reduced between baseline and 72 hours. Conclusion: There is a cognitive deficit and symptom burden in patients with mild TBI presenting to the Emergency Department which persists at 72 hours.

Letter in Response to ‘Classification of Traumatic Brain Injury Severity Using Informed Data Reduction in a Series of Binary Classifier Algorithms’

Presents letters to the editor.