EM Evidence Rundown — Issue 31

EM EVIDENCE RUNDOWN — ISSUE 31 — 25 SEPTEMBER 2026

EM Evidence Rundown

Emergency medicine evidence for UK clinicians — weekly — emevidence.org

Jake Turner — Senior Registrar in Emergency Medicine, ST6 — Curated with the assistance of AI (Perplexity). All content editorially reviewed.

Lead (Analgesia): Morphine + IV paracetamol vs morphine alone in acute ED pain — multicentre double-blind RCT (JAMA Network Open, n=424, 11 French EDs): morphine alone did NOT meet noninferiority. Adding IV paracetamol reduced 30-minute pain more and cut rescue analgesia need from 13% to 2% in nontraumatic pain. Multimodal analgesia remains the standard. Change This Week: Syncope/presyncope: hospitalisation has diagnostic yield only in higher-risk patients. FAINT=0 patients show no benefit from admission in this prospective study (n=1,263). Discharge low-risk syncope with outpatient monitoring rather than admitting reflexively. Informing: Anaphylaxis observation: a risk-stratified approach is supported by 10 years of data. The 6-hour inflection point aligns with NICE CG134. Psychiatric patients presenting to ED: routine bloods are not supported by society guidelines across 145 studies. Paediatric EM (4 items): IV dexamethasone for paeds migraine relapse does NOT work (RCT, ARD -4%); POCUS improves paeds urethral catheterisation success (NNT=6); selective CT guided by decision rules is supported in paeds blunt abdominal trauma; anaphylaxis risk-stratification in children. Core Revision: WPW and Pre-Excitation — the delta wave, pre-excited AF (the dangerous rhythm), why AV-nodal blockers are contraindicated, DCCV, and ablation. FRCEM-relevant.

BOTTOM LINE UP FRONT — 25 SEPTEMBER 2026

ACT ON THIS NOW

LEAD Morphine + IV paracetamol (JAMA Netw Open 2026): Morphine alone does not meet noninferiority vs morphine + IV paracetamol at 30 min. Rescue analgesia: 13% vs 2% in nontraumatic pain. Use multimodal analgesia (paracetamol + morphine) as standard for severe acute ED pain. IV paracetamol is not always needed — oral achieves comparable levels if patient can swallow.

CHANGE Syncope discharge (AEM 2026, n=1,263): FAINT=0 patients get no diagnostic yield from hospitalisation. Discharge low-risk syncope with ambulatory cardiac monitoring rather than admitting. FAINT ≥1: hospitalisation detects SAO in 8% (vs 2.1% if discharged).

INFORMING Anaphylaxis obs (10-yr data): 6h is the inflection point. Low-risk: 1-4h. High-risk: 6-12h. Universal 24h observation is not supported. Align with NICE CG134. Key risk factor: need for 2+ adrenaline doses.

UK RCEM ACP statement: ACPs are an integral and valued part of the ED workforce. Clinical activity must be under supervision of a tier 4/5 doctor. Do not normalise unsupervised ACP practice. Support credentialled ACP development.

KNOW FOR NEXT TIME

PAEDS EM IV dexamethasone for paeds migraine (RCT, n=87): Relapse 39% vs 44% placebo; ARD -4% (CI -32 to 24%). Do not use IV dexamethasone routinely for paediatric migraine relapse prevention. Standard rescue therapy (IV metoclopramide + diphenhydramine) remains the priority.

PAEDS EM POCUS for paeds catheterisation (SR/MA, n=337): First-attempt success 89.7% vs 72.5% (NNT=6). Reduced futile attempts from 23.9% to 3.6%. Use POCUS-guidance for catheterisation in young children where available.

PAEDS EM CT in paeds abdominal trauma (SJTREM SR): Intervention rate 7.7%, mortality 1.4%. Selective CT with clinical decision rules is supported. Avoid routine CT for all paeds blunt abdominal trauma.

CORE REVISION WPW — pre-excited AF is broad/irregular/fast >200 bpm. NEVER give AV nodal blockers. DC cardiovert immediately if unstable. FRCEM.

This week's lead is a rigorous double-blind trial that puts to rest a long-standing debate in EM analgesia: adding IV paracetamol to morphine provides meaningful benefit at 30 minutes compared with morphine alone, particularly for nontraumatic pain. The clinical implication is not to always reach for IV paracetamol specifically — oral achieves equivalent bioavailability in patients who can swallow — but to ensure you are using multimodal analgesia rather than opioid monotherapy. The syncope paper provides the first prospective data supporting risk-stratified rather than reflexive admission of syncope patients. Paediatric EM has four items this week, including a genuinely negative trial for IV dexamethasone in paediatric migraine and strong evidence for POCUS-guided catheterisation in young children. The core revision covers WPW — a high-stakes ECG diagnosis with a lethal arrhythmia variant (pre-excited AF) that requires DCCV, not drugs.

WHAT'S INSIDE — ISSUE 31

• Lead: Morphine + IV paracetamol vs morphine alone (JAMA Netw Open)
• Change: Syncope/presyncope — FAINT=0, no benefit from admission
• Informing: Anaphylaxis observation — 6h inflection point (NICE aligned)
• Informing: Medical screening of psychiatric ED patients — scoping review
• UK: RCEM reaffirms support for Advanced Clinical Practice
• PEM: IV dexamethasone for paeds migraine relapse — no benefit (RCT)
• PEM: POCUS for paediatric urethral catheterisation — NNT=6
• PEM: CT in paediatric blunt abdominal trauma — selective use supported
• PEM: Anaphylaxis — risk-stratified observation (also adult section)
• FOAMed: EMCrit 434 — Temporary Haemodialysis Catheters
• FOAMed: SGEM#520 — Morphine + IV paracetamol RCT
• Core Revision: WPW and Pre-Excitation (ECG)

Contents: 1. Key Trials & Articles — 2. Guidelines & UK Updates — 3. Paediatric Emergency Medicine — 4. FOAMed & Critical Appraisal — 5. Action Points — 6. Trials to Watch — 7. Core Revision: WPW (ECG)

1 — KEY TRIALS & ARTICLES

LEAD DOUBLE-BLIND RCT FRCEM

Morphine Plus IV Paracetamol vs Morphine Alone for Acute ED Pain — Noninferiority Not Met (JAMA Network Open 2026)

Cattin G, Viglino D, Segard J, Volteau C, Chauvin A, Galinski M, et al. Morphine Plus Placebo vs Morphine Plus Acetaminophen for Acute Pain in the Emergency Department: A Randomized Clinical Trial. JAMA Netw Open. 2026;9(2):e2560250. doi:10.1001/jamanetworkopen.2025.60250. PMID: 41733913. French Ministry of Health funded. SGEM#520, 19 September 2026.

Design: Prospective, multicentre, double-blind, randomised, placebo-controlled noninferiority trial. 11 French EDs. Adults ≥18 years with acute severe pain (NRS ≥5/10) lasting <24 hours: traumatic (43%) or nontraumatic (57%). n=424 in modified intention-to-treat (mITT) population. Randomised to: (1) titrated IV morphine 0.1 mg/kg then 0.05 mg/kg every 10 min + placebo, or (2) identical morphine + 1g IV paracetamol. Primary outcome: mean NRS change from baseline to 30 minutes. Noninferiority margin: 1 NRS point. Noninferiority required both PP and mITT analyses to support it.

Key results: Morphine alone did NOT meet noninferiority to morphine + IV paracetamol in either pain stratum. For nontraumatic pain: per-protocol difference 0.80 NRS points (95% CI 0.19–1.41), mITT 0.76 (95% CI 0.11–1.41) — both CI upper bounds exceed the 1-point margin. For traumatic pain: PP difference 0.32 (95% CI −0.29 to 0.94) was within the margin, but the mITT confidence interval (0.36; 95% CI −0.28 to 1.01) narrowly missed noninferiority. The most clinically striking secondary finding: rescue analgesia was needed in 13% of the morphine-alone nontraumatic group vs only 2% with paracetamol (adjusted ARD −12pp; 95% CI −17.0 to −3.7; p=.01). Morphine consumption was similar between groups. No serious adverse events.

• 0.80 NRS DIFFERENCE FAVOURING PARACETAMOL (NONTRAUMATIC PAIN, PP; CI 0.19–1.41)
• 13% RESCUE ANALGESIA NEEDED: MORPHINE ALONE (NONTRAUMATIC)
• 2% RESCUE ANALGESIA NEEDED: MORPHINE + PARACETAMOL
• ARD -12pp RESCUE ANALGESIA (95% CI -17 TO -3.7; P=.01)

Critical appraisal: This is a well-designed double-blind RCT addressing a clinically important question. The noninferiority design is appropriate: the trial asks whether morphine alone is as good as morphine + paracetamol, which is a reasonable hypothesis given that morphine drives analgesia and paracetamol's additive effect might be modest. The study was severely disrupted by COVID-19, forcing a protocol amendment to reduce power from 90% to 80% — the traumatic-pain stratum was particularly underpowered (n=181 vs 572 planned). The result for traumatic pain is therefore less reliable than for nontraumatic pain, and the failure of noninferiority in traumatic pain is driven by the mITT CI touching 1.01 — a marginal result. For nontraumatic pain, the finding is cleaner and the CI is well above the margin. The rescue-analgesia finding (13% vs 2%) is arguably the most clinically meaningful result: even if the mean NRS difference at 30 minutes is <1 point, requiring rescue analgesia in 13% of the morphine-alone group represents a meaningful treatment gap. Importantly, this trial studied IV paracetamol — not the same as oral. In patients who can swallow, oral paracetamol achieves equivalent serum levels at a fraction of the cost and with no IV administration burden. The trial does not support universal IV paracetamol; it supports ensuring paracetamol is part of the analgesic plan wherever it can safely be given.

UK ED practice: For severe acute ED pain requiring IV morphine: always use multimodal analgesia. Give paracetamol 1g PO or IV (if PO not possible) alongside titrated IV morphine. Oral paracetamol is appropriate in most patients who can swallow — IV paracetamol should be reserved for patients who cannot take oral medication or where rapid effect is essential. Ensuring paracetamol and an NSAID are prescribed concurrently with opioids is a simple, low-cost step that reduces opioid requirements and rescue medication rates. Review your department's standard analgesic order set to include paracetamol as a default co-analgesic.

CHANGE THIS WEEK PROSPECTIVE OBSERVATIONAL FRCEM

Syncope/Presyncope: Hospitalisation Has Diagnostic Yield Only in FAINT ≥1 Patients — No Benefit for Low-Risk (FAINT=0)

Baugh CW, Winskill C, Suh EH, Sacco DL, DeAngelis J, et al. Diagnostic Yield of Hospitalization for Emergency Department Patients With Syncope and Presyncope. Acad Emerg Med. 2026;33(8):e70393. doi:10.1111/acem.70393. PMID: 42573572. JournalFeed EM Speed Read, 23 September 2026. NCT04533425.

Design: Planned secondary analysis of a prospective, multicentre, observational study. Six urban US EDs. Adults aged ≥40 years presenting with syncope or presyncope in whom no serious diagnosis was made during the ED visit. Enrollment September 2020–September 2024. n=1,263 (562 hospitalised, 700 discharged). Mean age 64.8 years. Primary outcome: serious adverse outcome (SAO) within 30 days, including death, significant cardiac arrhythmia, MI, structural heart disease, CPR, stroke, subarachnoid haemorrhage, sepsis, PE, aortic dissection, haemorrhage requiring transfusion, or cardiac intervention. Propensity-score adjustment and Bayesian logistic regression used to account for confounding. FAINT score subgroup analysis (FAINT: heart Failure, Age, Initial ECG abnormality, elevated N-terminal proBNP, elevated serum Troponin).

Key results: Any 30-day SAO: 5.9% overall. Among hospitalised patients, SAOs found during admission: 8.0% (45/562). Among discharged patients, SAOs within 30 days: 2.1% (15/700). Propensity-score-adjusted OR for SAO in hospitalised vs discharged: 3.70 (95% CrI 1.85–6.82). Time-to-SAO was substantially shorter in hospital (HR 12.43; 95% CI 2.94–52.48 during admission). The most common SAO was significant cardiac arrhythmia (37 patients, 2.9%), predominantly symptomatic SVT. In the FAINT=0 subgroup: OR 1.57 (95% CI 0.14–17.53) — no significant benefit from hospitalisation. In FAINT ≥1: OR 3.35 (95% CI 1.78–6.31) — significant diagnostic benefit. Notably, hospitalisation was associated with 13% iatrogenic adverse events (delirium, hypoglycaemia, falls).

• 5.9% 30-DAY SAO OVERALL (N=1,263)
• 8.0% SAO FOUND DURING ADMISSION (HOSPITALISED)
• 2.1% SAO WITHIN 30 DAYS (DISCHARGED)
• 13% IATROGENIC ADVERSE EVENTS FROM HOSPITALISATION

Critical appraisal: This prospective multicentre study provides the strongest available evidence on the diagnostic yield of syncope hospitalisation. The study is not an RCT — patients were not randomly assigned to admission or discharge, and despite sophisticated propensity-score adjustment, residual confounding is inevitable (sicker patients were more likely to be admitted and more likely to have SAOs). The FAINT=0 finding is particularly useful: OR 1.57 with a very wide CI (0.14–17.53) reflects small numbers in this subgroup and does not definitively prove that hospitalisation is harmful for low-risk patients — but it strongly suggests no measurable benefit. The study enrolled patients aged ≥40 years from six urban US academic EDs — generalisability to younger patients and to UK DGH populations is uncertain. The key practical message is not that all syncope patients should be discharged, but that admission for monitoring is a meaningful diagnostic strategy in higher-risk patients (particularly those with abnormal ECGs, elevated biomarkers, or cardiac history), while adding no demonstrable diagnostic yield for genuinely low-risk patients.

UK ED practice: Use a validated risk score (FAINT, ROSE, Canadian Syncope Risk Score) to guide disposition decisions in unexplained syncope. FAINT=0: discharge with prompt ambulatory cardiac monitoring (patch monitor for 1–2 weeks or implantable loop recorder for recurrent unexplained syncope). FAINT ≥1: hospitalisation for monitoring and workup is justified. Do not admit all syncope reflexively — 13% of hospitalised patients in this study had iatrogenic harm. Presyncope carries similar 30-day serious cardiac outcome risk to syncope — do not dismiss it as low-risk solely because consciousness was preserved.

INFORMING NARRATIVE REVIEW 10 YEARS

Anaphylaxis Observation: 6-Hour Inflection Point, Risk-Stratified Approach — 10 Years of Data (NICE CG134 Aligned)

Abouelmagd K, Alhaddad J, Oyedele TJ, Ali RR, et al. Post-anaphylaxis observation in the ED: a decade of data challenging the traditional 24-hour rule. Int J Emerg Med. 2026;19:63. doi:10.1186/s12245-026-01175-4. PMID: 41832433. JournalFeed Paeds Speed Read, 24 September 2026.

Design: Narrative review. Literature searched from January 2015 to November 2025. Included systematic reviews, meta-analyses, large cohort studies, and major society guidelines. Synthesises data on biphasic anaphylaxis incidence, timing, risk factors, and the evidence for various observation durations.

Key findings: Biphasic anaphylaxis occurs in approximately 4–6% of cases (pooled incidence 4.6%, Lee et al. 2015 SR; 4.9%, Kim et al. 2019 meta-analysis). Median onset of biphasic reactions: 11 hours (range 0.2–72 hours); more than half occur after 4–6 hours. The most consistent risk factor for biphasic reaction is the need for two or more adrenaline doses. Food-triggered reactions carry lower biphasic risk (OR 0.62); unknown-trigger and initial hypotension carry higher risk. Observation duration evidence: NPV at 2h approximately 95.8% (42 missed reactions per 1,000 discharged); at 6h 97.3% (27 missed/1,000); beyond 8h marginal additional benefit. The 6-hour mark is the inflection point beyond which incremental benefit diminishes markedly in unselected populations. NICE CG134 recommends 6–12h observation based on treatment response, and a shorter period only for promptly resolved low-risk reactions with robust aftercare.

• 4–6% BIPHASIC ANAPHYLAXIS INCIDENCE (POOLED ACROSS STUDIES)
• 11h MEDIAN TIME TO BIPHASIC REACTION ONSET
• 97.3% NPV AT 6H OBSERVATION (KIM 2019 MA, N=2,890)
• 6h INFLECTION POINT: MARGINAL GAIN BEYOND THIS IN UNSELECTED PATIENTS

Critical appraisal: This is a narrative rather than systematic review — it does not perform formal pooled analysis and synthesises evidence selectively. The heterogeneity in biphasic anaphylaxis definitions, populations, and observation periods across included studies makes direct comparison difficult. Reported biphasic rates range from 1% to 20% across studies (with most between 4–6%), reflecting genuine variation in patient populations and case-mix. The 6-hour inflection point is a reasonable clinical heuristic derived from the Kim et al. meta-analysis, but the NPV difference between 2h (95.8%) and 6h (97.3%) represents only 15 fewer missed reactions per 1,000 patients — a clinically modest benefit. The review's important UK-specific content is its explicit alignment with NICE CG134, which recommends 6–12h observation as standard with shorter periods only for promptly controlled low-risk presentations.

UK ED practice: Follow NICE CG134. Low-risk features (single adrenaline dose, rapid complete resolution, known food trigger, no hypotension/hypoxia/asthma, reliable home support): 1–4h observation acceptable with robust discharge plan. High-risk features (two or more adrenaline doses, delayed response to adrenaline, unknown trigger, cardiovascular compromise, asthma, beta-blocker use, mast cell disorder, limited home support): minimum 6h, typically 6–12h. Consider admission for multiple risk factors or persistent instability. Every discharge: adrenaline auto-injector prescription, correct technique demonstration, written action plan, allergy referral arranged.

INFORMING SCOPING REVIEW

Medical Screening of Psychiatric Patients in the ED: Routine Labs Are Not Supported Across 145 Studies

Unlu L, Griese JA, Minotti B, Carpenter CR, Appenzeller-Herzog C, et al. Medical Screening of Adult Psychiatric Patients Presenting to the Emergency Department. Ann Emerg Med. 2026; doi:10.1016/j.annemergmed.2026.04.001. PMID: 42233919. EMA Daily, 24 September 2026.

Design: Scoping review. Databases searched: Medline, PsycInfo, EMBASE, Web of Science (from inception to April 2025). 9,128 records screened, 145 publications included (62 original research articles representing 34,836 patients; 74 nonoriginal publications; 9 society recommendations). Predominantly retrospective studies (59.7%).

Key findings: Medical screening practices for psychiatric ED presentations can be categorised into 8 domains: laboratory testing (62.9% of studies), history taking, vital signs, physical examination, diagnostic imaging, medical screening tools, ECG, and system-level factors. The most important finding: most society recommendations explicitly discourage routine laboratory testing for psychiatric emergency presentations. None of the society recommendations were developed using gold-standard guideline methodology (National Academy of Medicine criteria or GRADE). The review calls for high-quality prospective evidence on the diagnostic accuracy of specific screening components.

Critical appraisal: This scoping review maps the literature rather than synthesising it analytically — it does not provide pooled diagnostic accuracy figures or practice-changing recommendations. Its value lies in documenting that the evidence base for medical "clearance" is predominantly retrospective, heterogeneous, and that current society recommendations universally discourage the reflexive ordering of full blood counts, glucose, and routine biochemistry for every psychiatric presentation. This has practical significance: routine labs in the absence of specific clinical indication add cost, delay, and false-positive results that can prevent timely psychiatric assessment. The review reinforces a focused, history-and-examination-driven approach to identifying patients who genuinely need medical investigation before psychiatric assessment.

UK ED practice: Do not order routine labs (FBC, U&E, LFT, glucose, TFT) for all psychiatric presentations to the ED. Perform a targeted history, vital signs (including temperature, SpO2, BM), and physical examination. Order investigations based on specific clinical indications: altered consciousness or known metabolic risk → glucose; suspected infection → CRP, WCC; medication toxicity (lithium, clozapine, antiepileptics) → relevant drug levels and renal function; undifferentiated delirium → broader screen. An ECG is appropriate in medication-related presentations and before starting QTc-prolonging drugs. Focused assessment reduces unnecessary delay and improves flow to liaison psychiatry review.

2 — GUIDELINES & UK UPDATES

UK RCEM

RCEM Reaffirms Strong Support for Advanced Clinical Practice in Emergency Departments — 22 September 2026

Royal College of Emergency Medicine. Press release. Published 22 September 2026. rcem.ac.uk

RCEM has reaffirmed its strong support for Advanced Clinical Practitioners (ACPs) as an integral part of the emergency department workforce, spanning nursing, paramedic science, physiotherapy, and pharmacy backgrounds. Key positions: ACPs complement and work collaboratively with doctors, and must not be used as medical substitutes. The most senior clinician in any ED must always be a tier 4 or 5 doctor with overall responsibility for clinical care and supervision. RCEM supports its own EM:ACP curriculum and credentialing framework, and calls for clarity around nomenclature, training pathways, qualifications, scope of practice, and supervision. RCEM acknowledges concerns about medical substitution, difficulties with training post availability, and medical unemployment, while strongly supporting safe ACP integration.

UK ED practice: Support credentialled ACPs in your department and ensure their scope of practice, supervision requirements, and governance arrangements are clearly defined and documented. If you are a doctor of any grade, understand your supervision responsibilities in relation to ACP colleagues. ACPs cannot replace the medical registrar or consultant at clinical or governance level. Use the RCEM EM:ACP credentialing pathway as the reference standard when assessing ACP capability in your department.

3 — PAEDIATRIC EMERGENCY MEDICINE

PAEDS EM DOUBLE-BLIND RCT NEGATIVE

IV Dexamethasone Does NOT Prevent Paediatric Migraine Relapse — RCT (n=87, ARD −4%)

Tourigny-Ruel G, Bailey B, Jean-Charles S, Gravel J. Randomized controlled trial of intravenous dexamethasone to prevent relapse in the treatment of migraine in a pediatric emergency department. Headache. 2026 Apr 3. doi:10.1111/head.70087. PMID: 41933931. EMA Daily, 18 September 2026.

Design: Randomised, double-blind, placebo-controlled trial. Single tertiary paediatric ED (CHU Sainte-Justine, Montreal, Canada). Children aged 8–17 years with acute migraine requiring IV rescue therapy. n=116 enrolled (July 2013–February 2025); 87 (75%) provided 48-hour outcome data in the mITT population. Intervention: dexamethasone 0.6 mg/kg IV (max 15 mg) before discharge, vs placebo. Standard rescue therapy: IV metoclopramide + diphenhydramine. All received oral naproxen for 48 hours post-discharge. Primary outcome: relapse within 48 hours (recurrence or worsening of headache after initial improvement).

Key results: Relapse at 48 hours: 39% dexamethasone (16/41) vs 44% placebo (20/46). Absolute risk difference: −4% (95% CI −32% to 24%). This confidence interval comfortably crosses zero — the study demonstrates no significant benefit from IV dexamethasone for preventing paediatric migraine relapse. Pain scores, return to school, functional recovery, and healthcare revisits did not differ significantly between groups. Adverse events were infrequent and mild in both arms.

• 39% RELAPSE AT 48H: DEXAMETHASONE (16/41)
• 44% RELAPSE AT 48H: PLACEBO (20/46)
• ARD −4% 95% CI −32% TO 24%; P=NS

Critical appraisal: The trial is appropriately designed (double-blind, placebo-controlled) but severely underpowered — the original sample-size calculation was not stated, but the 75% follow-up from 116 enrolled yields only 87 patients in the primary analysis, which is insufficient to detect a clinically meaningful difference of 15–20 percentage points with 80% power. The wide confidence interval (−32% to +24%) reflects this imprecision; the study cannot exclude a clinically meaningful benefit or harm. However, this is consistent with adult data where IV dexamethasone for migraine relapse prevention has shown similarly unreliable results across trials. The study ran for 12 years (2013–2025), which may introduce secular changes in migraine management protocols. Despite its limitations, this trial adds to a pattern of evidence that dexamethasone is not a reliable migraine rescue adjunct in the paediatric population, and the prolonged trial duration without a clear signal should reduce enthusiasm for routine use.

UK PEM practice: Do not routinely add IV dexamethasone to the migraine rescue protocol in paediatric ED patients in the hope of preventing relapse. Standard rescue therapy (IV metoclopramide 0.15–0.25 mg/kg + IV prochlorperazine or equivalent) plus oral ibuprofen and hydration remains the evidence-based approach. For refractory migraine: involve paediatric neurology. Ensure a confirmed migraine diagnosis and document red flag exclusions (meningism, thunderclap headache, focal neurology, papilloedema).

PAEDS EM SR/MA 3 RCTS

POCUS Guidance for Paediatric Urethral Catheterisation — SR/MA: First-Attempt Success 89.7% vs 72.5%, NNT=6

Vieira da Silva HF, Watanabe ET, Tavares MC, et al. Point-of-Care Ultrasound for Pediatric Urethral Catheterization: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Acad Emerg Med. 2026;33(6):e70342. doi:10.1111/acem.70342. PMID: 42246462. JournalFeed Paeds Speed Read, 17 September 2026.

Design: Systematic review and meta-analysis of RCTs (PRISMA). Databases: PubMed, Embase, CENTRAL. PROSPERO registered. 3 RCTs included; 337 participants (children aged ≤36 months). Intervention: real-time POCUS-assisted urethral catheterisation vs standard blind technique. Primary outcome: first-attempt catheterisation success rate. Evidence certainty: moderate for the primary outcome.

Key results: First-attempt success: POCUS 89.7% vs standard 72.5% (RR 1.25; 95% CI 1.08–1.45; p=0.0022; NNT=6). Futile attempts ("dry taps"): POCUS 3.6% vs standard 23.9% (RR 0.25; 95% CI 0.13–0.47; p<0.0001; NNT=5 to prevent one futile attempt). Higher caregiver satisfaction and lower perceived patient distress with POCUS. Workflow time was not significantly increased despite the requirement for bladder filling confirmation before the procedure.

• 89.7% FIRST-ATTEMPT SUCCESS: POCUS
• 72.5% FIRST-ATTEMPT SUCCESS: STANDARD TECHNIQUE
• NNT=6 TO GAIN ONE ADDITIONAL FIRST-ATTEMPT SUCCESS
• 23.9% FUTILE ATTEMPTS: STANDARD (VS 3.6% POCUS)

Critical appraisal: Only 3 RCTs included (n=337 total) — this is a small meta-analysis. Evidence certainty is moderate for the primary outcome. All included studies may not have been conducted in UK ED populations. The POCUS technique involves scanning the suprapubic area to confirm a distended bladder before catheterisation, which is a simple and rapidly acquired skill. The magnitude of effect (first-attempt success +17pp, futile attempts -20pp, NNT=6) is clinically meaningful and consistent across included trials. The study population is young children ≤36 months — a group in whom blind catheterisation failure is common due to poor anatomical landmarks, particularly in girls. Moderate certainty evidence with consistent direction supports adoption of this technique wherever POCUS is available.

UK PEM practice: Where POCUS equipment is available in your paediatric ED, use real-time bladder POCUS to guide urethral catheterisation in young children (≤36 months), particularly for girls. The technique: suprapubic scan to confirm a bladder with adequate volume before attempting catheterisation, and real-time visualisation during the procedure if feasible. This reduces futile attempts and distress for child and family. Incorporate POCUS-guided catheterisation into your paediatric POCUS training curriculum. Where POCUS is not available, ensure experienced operators perform the procedure and communicate the risk of multiple attempts to families.

PAEDS EM SR/MA

CT in Paediatric Blunt Abdominal Trauma: Selective Use Supported — Intervention Rate 7.7%, Mortality 1.4%

Alsabri M, Rath S, Elkarargy MA, et al. Computed tomography in pediatric blunt abdominal trauma: current evidence, challenges, and future directions — a systematic review and meta-analysis. Scand J Trauma Resusc Emerg Med. 2026. doi:10.1186/s13049-026-01578-5. PMID: 41654849. JournalFeed Paeds Speed Read, 22 September 2026.

Design: Systematic review and meta-analysis. Databases: PubMed, Web of Science, Cochrane, Scopus (through August 2025). 15 studies, 7,430 children. Bayesian random-effects meta-analyses. GRADE framework applied.

Key results: Among paediatric patients imaged by CT for blunt abdominal trauma, the pooled posterior median prevalence of intra-abdominal injury (IAI) was 84.5% (95% CrI 62–94%) — but this represents a highly selected population who had already been sent for CT. More importantly: the probability of requiring any intervention was only 7.7%, and mortality was 1.4%. Solid organ injuries predominated (liver 13.1%, bowel 11.2%, spleen 11.1%). Meta-regression showed higher IAI probability with increasing age and male sex. Certainty of evidence was moderate for overall IAI prevalence, low for other outcomes.

Critical appraisal: This SR synthesises evidence from studies where CT was already performed, creating significant selection bias — the high 84.5% IAI prevalence reflects clinicians' appropriate use of CT in children with clinical concern, not a rate applicable to all blunt abdominal trauma. The critically important finding is the low intervention rate (7.7%) and mortality (1.4%), which supports the principle that most CT-detected IAIs in children are managed non-operatively. This underpins the use of validated clinical decision rules (PECARN abdominal trauma rule, FAST examination) to identify children who truly need CT, rather than scanning all blunt abdominal trauma presentations. The PECARN abdominal trauma prediction rule identifies children at very low risk of clinically important IAI who can safely avoid CT — seven clinical predictors are validated for this purpose.

UK PEM practice: Use the PECARN paediatric blunt abdominal trauma decision rule to guide CT use. Very-low-risk features (no abdominal tenderness, no GCS alteration, no vomiting, no thoracic wall trauma, no abdominal wall trauma or seatbelt sign, no decreased breath sounds): CT can safely be avoided. Selective use of CT in children reduces cumulative radiation exposure and is supported by the low intervention rate in those who test positive. For clinically unstable children: bedside FAST first, urgent surgical referral, CT only if stable and uncertainty about injury extent remains.

PAEDS EM EVIDENCE REVIEW

Paediatric Anaphylaxis: Low-Risk, Short-Observation Pathways Lead to Faster Discharge Safely

Same paper as above (PMID: 41832433). JournalFeed Paeds Speed Read, 24 September 2026.

As discussed in the adult anaphylaxis section, the paediatric data in this review (Short et al. 2024, n=292 children) show a biphasic rate of 3.4% — lower than many adult series. Biphasic reactions in children occurred as late as 33 hours post-discharge, but four of six events in the first 2.5 hours were relatively early. Paediatric triggers are predominantly food-related (lower biphasic risk), and most paediatric anaphylaxis is managed with a single adrenaline dose. NICE CG134 recommends admission of children <16 years under paediatric care rather than brief ED discharge — this remains the UK standard. For children in whom a truly low-risk picture is confirmed (single adrenaline, food trigger, complete resolution, no asthma or significant comorbidity): a risk-stratified shorter observation period may be considered, but only with senior paediatric sign-off and robust discharge arrangements.

UK PEM practice: Children <16 years with anaphylaxis should be reviewed by the paediatric team before discharge per NICE CG134. Mandatory discharge bundle: adrenaline auto-injector x2 prescribed (show technique), written action plan, instructions on recognising biphasic reactions, allergy referral arranged. Do not discharge before a minimum 4–6h observation in most paediatric cases, with longer periods for high-risk features.

4 — FOAMED & CRITICAL APPRAISAL

EMCRIT FRCEM

EMCrit 434 — Temporary Haemodialysis Catheters: Site Selection, Venous Confirmation, and Avoiding Catastrophic Complications

Scott Weingart. EMCrit. Published 21 September 2026. emcrit.org/emcrit/hd-caths/

Weingart argues that waiting for outside renal services or HD fellows to place emergent dialysis catheters directly harms critically ill patients requiring immediate RRT or exchange transfusion. The episode covers non-tunnelled HD catheter selection (12F standard, 15–16 cm for RIJ, 24 cm for femoral), site hierarchy (RIJ first, femoral second, LIJ third, subclavian last resort — subclavian destroys future AV fistula options), and three critical procedural rules: (1) always confirm venous entry before passing any dilator (pressure transduction, agitated-saline bubble test, or micropuncture), (2) use real-time ultrasound throughout, (3) if a 12F catheter is accidentally dilated into an artery, do NOT pull it out — leave it in place and call vascular surgery. Guidewire exchange of a non-infected RIJ central line for an HD catheter is safe. BMI matters for femoral access: BMI <24 kg/m² — femoral lower colonisation risk; BMI >28 kg/m² — strongly prefer jugular. Episode also covers the use of HD catheters as large-bore resuscitation lines in massive haemorrhage (label clearly: "for massive transfusion only — not prepared for dialysis").

UK context: ED clinicians in UK major trauma centres and resuscitation units should be capable of placing temporary non-tunnelled HD catheters in genuinely emergent situations. Ensure your department has the correct catheter sizes stocked (12F, 16 cm for RIJ; 24 cm for femoral). Know the venous confirmation steps before dilation — accidental arterial dilation with a 12F catheter is catastrophic. Train with ultrasound before you need this skill in extremis. This skill is not commonly required in district general emergency departments but is expected at major resuscitation and trauma centre level.

SGEM FRCEM

SGEM#520 — Morphine Plus IV Paracetamol: Does Acetaminophen Really Add Benefit?

The Skeptics Guide to Emergency Medicine. SGEM#520. Published 19 September 2026. thesgem.com. Guest: Dr Caitlin Jones (Sydney University musculoskeletal research).

SGEM reviews the Cattin et al. JAMA Network Open trial (lead item this issue). Ken Milne and Dr Jones provide an accessible critical appraisal of the noninferiority trial design, the COVID disruption that underpowered the traumatic-pain stratum, and the clinical interpretation of "failure of noninferiority." Key SGEM bottom line: morphine alone did not meet the criterion for noninferiority to morphine + IV paracetamol, particularly for nontraumatic pain, and the rescue-analgesia finding (13% vs 2%) is clinically meaningful. However, this does not mean every patient receiving IV morphine needs IV paracetamol — for patients who can tolerate oral medication, inexpensive oral paracetamol achieves equivalent levels and should be co-prescribed routinely. The SGEM episode is recommended listening alongside this issue's lead.

5 — ACTION POINTS

4

Psychiatric screening bloods: Stop ordering routine bloods (FBC, U&E, LFT) for every psychiatric presentation. Targeted investigation based on specific clinical indications only. Review your department's "medical clearance" pathway to ensure it reflects current evidence.

6 — TRIALS TO WATCH

ONGOING / EXPECTED

CORE REVISION — ISSUE 31 — 25 SEPTEMBER 2026

WPW and Pre-Excitation

The delta wave, pre-excited AF, why AV nodal blockers are dangerous, DCCV, treatment — FRCEM

Exam goal: Describe the WPW ECG pattern (short PR, delta wave, wide QRS); distinguish WPW pattern from WPW syndrome; explain orthodromic AVRT; recognise pre-excited AF (broad, irregular, fast >200 bpm, variable QRS width); explain why AV nodal blockers are absolutely contraindicated in pre-excited AF; state the treatment (DCCV); describe the long-term management pathway; localise the accessory pathway from the delta-wave axis. FRCEM exam regularly tests these principles — particularly the "drugs to avoid" list and the mechanism of danger in pre-excited AF.

1. THE WPW ECG PATTERN (NORMAL SINUS RHYTHM)

In WPW, an accessory pathway (the bundle of Kent) provides a direct connection between atria and ventricles, bypassing the AV node. In sinus rhythm, the accessory pathway conducts faster than the AV node — so ventricular depolarisation begins via the accessory pathway before the normal AV nodal conduction arrives. This creates a "fusion beat" where the early accessory pathway activation produces the characteristic features:

WPW pattern vs WPW syndrome: WPW pattern = the ECG findings alone. WPW syndrome = WPW pattern + documented SVT or symptoms (palpitations, syncope). Only approximately 50% of patients with a WPW pattern on ECG ever develop clinical WPW syndrome. Intermittent pre-excitation (some beats pre-excited, some not) indicates a lower-risk accessory pathway incapable of sustaining rapid conduction.

2. ARRHYTHMIAS IN WPW

3. RECOGNISING PRE-EXCITED AF

Pre-excited AF is the most dangerous arrhythmia associated with WPW. The ECG features are distinct and must be recognised immediately:

Mnemonic for pre-excited AF on ECG: "FIRE" — Fast (>200), Irregular, Really broad, Erratic QRS morphology.

4. WHY AV NODAL BLOCKERS ARE ABSOLUTELY CONTRAINDICATED IN PRE-EXCITED AF

This is the most important and most frequently examined fact about WPW. In pre-excited AF, two pathways are conducting: the AV node and the accessory pathway. They compete, and the AV node's refractoriness partly limits how fast the accessory pathway can drive the ventricles (because a ventricular beat from the AV node can render the accessory pathway transiently refractory).

If you block the AV node with any AV-nodal blocking drug, you remove this natural competition. The accessory pathway gains complete, uninhibited control of ventricular rate. This can accelerate the ventricular rate dramatically and cause ventricular fibrillation and cardiac arrest.

ABSOLUTELY CONTRAINDICATED in pre-excited AF:

AMAD: Adenosine, Metoprolol/beta-blockers, Amiodarone, Diltiazem/verapamil/calcium channel blockers Any drug that slows the AV node is contraindicated. Amiodarone is included despite sometimes being used as a "safe" antiarrhythmic — its AV nodal blocking effects make it dangerous in pre-excited AF. Even digoxin (AV nodal blocker) is contraindicated.

5. TREATMENT OF PRE-EXCITED AF

Unstable patient (hypotension, reduced consciousness, severe ischaemia): DC cardioversion immediately. Synchronised cardioversion. Do not delay for drug treatment. Sedate if conscious and time permits, but prioritise cardioversion.

Stable patient: Options that work on the accessory pathway rather than the AV node:

In most UK ED scenarios: if a patient is in pre-excited AF, the safest approach is early DCCV regardless of haemodynamic stability, given the limited availability of procainamide and ibutilide. Have a senior cardiologist involved urgently.

6. TREATMENT OF ORTHODROMIC AVRT (NARROW COMPLEX, REGULAR)

Treat the same as AVNRT (the common narrow complex SVT):

KEY DISTINCTION: Adenosine IS safe in narrow-complex orthodromic AVRT (the circuit runs through the AV node and adenosine terminates it). Adenosine is dangerous ONLY when there is pre-excited AF (broad, irregular, >200 bpm) — never give adenosine to diagnose or treat a broad irregular tachycardia.

7. LONG-TERM MANAGEMENT

All patients with confirmed WPW syndrome (pattern + documented arrhythmia) should be referred for electrophysiology (EP) study. EP study maps the accessory pathway and assesses its refractory period — short refractory period (<250 ms) indicates high risk for rapid ventricular conduction in AF. Catheter ablation of the accessory pathway is curative in >95% of cases and is the definitive treatment for symptomatic WPW. Asymptomatic WPW pattern: risk stratification by EP study may be considered, but the evidence for benefit of prophylactic ablation in truly asymptomatic patients is less clear. Sports/high-risk occupation: EP study is usually recommended.

8. LOCALISING THE ACCESSORY PATHWAY FROM THE ECG

The delta wave polarity across leads helps localise the accessory pathway. The key principle: the delta wave vector points away from the pathway location. A simplified clinical rule:

For FRCEM purposes: you are not expected to precisely localise the pathway from the ECG, but understanding that different lead patterns reflect pathway position is useful context. What matters most is recognising the WPW pattern, identifying pre-excited AF, and knowing the management.

FRCEM exam focus: (1) WPW ECG = short PR (<120 ms) + delta wave (slurred QRS upstroke) + widened QRS. (2) WPW pattern vs WPW syndrome (pattern + documented SVT). (3) Pre-excited AF = broad, irregular, fast (>200 bpm), variable QRS width — the most dangerous arrhythmia. (4) NEVER give AV nodal blockers in pre-excited AF: adenosine, diltiazem, verapamil, metoprolol, amiodarone, digoxin are all contraindicated. (5) Unstable pre-excited AF: DCCV immediately. (6) Orthodromic AVRT (narrow, regular): treat as AVNRT — vagal manoeuvres → adenosine → DCCV. (7) Long-term: EP study and catheter ablation. (8) Adenosine IS safe in narrow-complex orthodromic AVRT; dangerous only in pre-excited AF.

EM Evidence Rundown — Issue 31 — 25 September 2026 Curated by Jake Turner, Senior Registrar in Emergency Medicine (ST6). Produced with the assistance of AI (Perplexity). All content editorially reviewed. Not a substitute for clinical judgement or local guidelines. Feedback: Submit feedback | Archive: emevidence.org Unsubscribe: Reply UNSUBSCRIBE to this email. To update your preferences, visit emevidence.org