EM Evidence Rundown — Issue 22

EM EVIDENCE RUNDOWN — ISSUE 22 — 24 JULY 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.

This week: Fosfomycin RCT establishes oral step-down for ESBL UTI as a carbapenem-sparing strategy. HYDRA trial confirms YEARS algorithm is safe in cancer patients with suspected PE. GMC Training Survey highlights corridor care is actively harming EM training quality. NHS England winter planning letter names corridor care elimination a patient safety priority. PEM: intranasal midazolam high-dose (0.5 mg/kg) works better for paediatric procedural sedation, and troponin 0/1 pathway is non-inferior to 0/3 for safety. Safety: MHRA EL(26)A/35 — Xaggitin XL (methylphenidate) incorrect tablet counts in Schedule 2 controlled drug batches; physical count check required on receipt. Core Revision: Sinus tachycardia — a first-principles physiology map (Supply / Demand / Perfusion).

BOTTOM LINE UP FRONT

ACT ON THIS NOW

CHANGE THIS MONTH ESBL UTI: Oral fosfomycin non-inferior to IV beta-lactam for step-down in ESBL complicated UTI (n=193, RCT). Avoid unnecessary carbapenem continuation.

CHANGE THIS MONTH Paeds sedation: Intranasal midazolam 0.5 mg/kg reduces need for rescue sedation vs 0.2 mg/kg. Increase your default dose for ED procedural sedation.

SAFETY MHRA EL(26)A/35: Xaggitin XL (methylphenidate, Schedule 2) — incorrect tablet counts. Physically count on receipt. All strengths 27/36/54 mg affected.

CHANGE THIS MONTH Troponin pathway: 0/1 hr ESC algorithm non-inferior to 0/3 hr for safety of discharge. Median length of stay reduced. Consider local adoption.

INFORMING PRACTICE YEARS in cancer PE: HYDRA trial (n=683 RCT) confirms YEARS algorithm safe in cancer patients; 22% avoided CTPA. NI margin met. Apply with appropriate posterior risk caution.

CHANGE THIS MONTH Tox consult: Bedside toxicology consultation associated with higher appropriate ED discharge rates (13,241 patients). Request early for complex overdose.

KNOW FOR NEXT TIME

INFORMING PRACTICE NHS winter letter: Corridor care named a patient safety priority. Model ED requirements must be in place before winter. Board assurance due 30 September 2026.

INFORMING PRACTICE RCEM/GMC survey: Corridor care actively degrading EM trainee supervision quality. RCEM calls for action. FRCEM curriculum continuity at risk.

INFORMING PRACTICE Delayed discharges: 570,957 delayed discharge incidents in 2025/26 (Age UK/RCEM). Delayed transfers drive corridor care — system fix not ED fix required.

INFORMING PRACTICE Paeds sepsis markers: Base deficit and alactic base excess outperform lactate alone for early shock prediction in paediatric sepsis (n=44, preliminary).

INFORMING PRACTICE Intussusception: Age >48 months, symptoms >48 hrs, constipation + bowel wall thickening on US predict hydrostatic reduction failure (n=231). Prompt surgical review.

INFORMING PRACTICE NICE sepsis update: Procalcitonin guidance (GID-NG10467) delayed to 11 September 2026. No change to current NG253 pathway.

The NHS often feels like a slow-moving system, but this week saw two sharply practical papers — one clinching oral fosfomycin as a carbapenem-sparing step-down option for ESBL urinary infections, another confirming YEARS is safe even in cancer patients with suspected PE. Both carry immediate ward-round and resus implications. Meanwhile, the RCEM and GMC Training Survey have given us something uncomfortable to sit with: corridor care is not just bad for patients, it is measurably damaging the quality of emergency medicine training. On the paediatrics front, a granular study of intussusception predictors offers a practical framework for anticipating hydrostatic failure, and higher-dose intranasal midazolam is now the evidence-backed default for paediatric procedural sedation. This issue also carries the Core Revision slot on sinus tachycardia physiology — a topic that repays first-principles thinking every time a clinician reaches too quickly for bisoprolol.

WHAT'S INSIDE

• ESBL UTI — fosfomycin oral step-down RCT (LEAD)
• HYDRA: YEARS algorithm in cancer PE (JAMA RCT)
• Toxicology consultation & triage outcomes
• PE and DOAC outpatient safety data
• UK Guidelines & NHS winter planning
• RCEM response: corridor care & training
• MHRA Xaggitin XL safety alert (Schedule 2)
• Paeds: high-dose intranasal midazolam RCT
• Paeds: intussusception reduction failure predictors
• Paeds: base deficit vs lactate in paediatric sepsis
• Troponin 0/1 vs 0/3 pathway comparison
• EMCrit RACC-Lit & RUSH 2.0 update
• Quick Hits — 5 items
• Core Revision: Sinus Tachycardia (Supply/Demand/Perfusion)

• Action Points & Trials to Watch

CHANGE TONIGHT immediate practice change CHANGE THIS MONTH act within the month GUIDELINE new or updated guidance INFORMING PRACTICE context for decisions SAFETY patient safety alert PEM paediatric EM UK SPECIFIC

FOAMED

S1 Key Trials | S2 UK Guidelines & Policy | S3 Paediatric EM | S4 FOAMed & Critical Appraisal | S5 Quick Hits | Core Revision: Sinus Tachycardia | S6 Action Points | Trials to Watch

SECTION 1 — KEY TRIALS & JOURNAL ARTICLES

LEAD CHANGE THIS MONTH ANTIMICROBIALS

Fosfomycin as Oral Step-Down for ESBL Complicated UTI — RCT Establishes Non-Inferiority

Seo JW et al. Clinical Infectious Diseases, ciag345. Published 18 June 2026. PMID: 42313397. pubmed.ncbi.nlm.nih.gov/42313397

Why it matters: ESBL-producing Enterobacterales UTIs are increasingly common in UK EDs and on short-stay wards. The reflex has been to continue intravenous carbapenems once started, for want of a validated oral option. This multicentre open-label RCT (South Korea) challenges that assumption directly.

Design: Adults admitted with complicated UTI (including pyelonephritis, catheter-associated, obstructed) caused by ESBL-producing Enterobacterales, who had clinically improved after initial IV antibiotics, were randomised to oral fosfomycin (3g every 48 hours) versus continued IV beta-lactam. Primary outcome: clinical and microbiological cure at test-of-cure.

• Non-inf PRIMARY OUTCOME MET
• Oral CARBAPENEM-SPARING
• Compl. COMPLICATED UTI ONLY
• n=193 MULTICENTRE RCT

Bottom line: Oral fosfomycin was non-inferior to continued IV beta-lactam for clinical and microbiological cure in ESBL complicated UTI in adults who had responded to initial IV therapy. This supports fosfomycin as a carbapenem-sparing oral step-down option for patients who are improving clinically.

UK / FRCEM context: Fosfomycin 3g sachets are available on NHS prescription. Local microbiology must confirm susceptibility before switching. This does not apply to uncomplicated cystitis (where single-dose fosfomycin already has evidence). In the ED, the practical application is early discharge planning for improving ESBL UTI patients: discuss with micro and document susceptibility. This does not change empirical antibiotic choice in the ED. UK hospitals are under antimicrobial stewardship pressure — early switch to oral reduces healthcare contact and IV line risk.

Critical appraisal: Open-label design (blinding not feasible), single-region RCT (South Korea ESBL patterns differ from UK), ESBL epidemiology and susceptibility patterns may not be directly transferable. Non-inferiority margin and primary cure definition should be checked against local pharmacy and micro standards. Small n (193) means effect size confidence intervals are wide. This is supportive evidence for a practice already recommended by some UK micro teams — it is not a mandate to switch without susceptibility testing.

CHANGE THIS MONTH PE / CHEST PAIN EMCRIT REVIEWED

HYDRA Trial: YEARS Algorithm Safe in Cancer Patients with Suspected PE — 22% Avoid CTPA

Akerboom B et al; Hydra Study Investigators. JAMA. Published online 12 July 2026. DOI: 10.1001/jama.2026.10676 | EMCrit review: emcrit.org/emnerd/the-case-of-the-malignant-cohort

Why it matters: Cancer patients with suspected PE are traditionally managed with direct CTPA — the YEARS algorithm (three clinical items + D-dimer) was validated in the general population, but its safety in cancer patients has been uncertain. The HYDRA trial fills this gap.

Design: Randomised, multicentre non-inferiority trial. Adults with active cancer and suspected PE were randomised to YEARS-based diagnostic algorithm versus CTPA-only strategy. Primary outcome: 90-day VTE or PE-related death rate.

• 1.8% YEARS ARM VTE/PE DEATH
• 5.5% CTPA-ONLY ARM
• 22% AVOIDED CTPA
• n=683 MULTICENTRE RCT

Bottom line: The YEARS algorithm met its non-inferiority margin (pre-specified: 2.6%) against CTPA-only in cancer patients. ARD: −3.7% (99.9% CI −8.8 to 1.4). 22% of YEARS-arm patients avoided CTPA. This is a pragmatic win for a population already overburdened with contrast-heavy investigations.

UK / FRCEM context: The YEARS algorithm (three items: haemoptysis, PE most likely diagnosis, clinical DVT; D-dimer threshold 1000 ng/mL if 0 items, 500 if ≥1 item) is already widely used in UK EDs. Applying it to cancer patients means: if all three YEARS items negative and D-dimer <1000 ng/mL, CTPA can be withheld. EMCrit commentary notes the posterior risk remains slightly higher than in non-cancer populations — clinical judgement is required and the strategy should align with local pathway agreements.

TOXICOLOGY CHANGE THIS MONTH

Bedside Toxicology Consultation Associated with Better Triage and Fewer Unnecessary Admissions (n=13,241)

McCabe DJ et al. Am J Emerg Med. 2026. PMID: 42314343. pubmed.ncbi.nlm.nih.gov/42314343

Among 13,241 poisoned patients, bedside medical toxicology consultation (where available) was associated with higher rates of appropriate ED discharge and correct escalation to ICU care, compared with patients managed without toxicology input. This suggests that integrating toxicology expertise early — including via telephone consultation where not available locally — may reduce unnecessary admissions and improve appropriate high-acuity triage.

UK context: Dedicated toxicology services exist in some UK centres (NPIS, Guy's toxicology). For UK EDs without on-site toxicologists, the National Poisons Information Service (NPIS) telephone line (0344 892 0111) fulfils an equivalent function. The practical take: use TOXBASE and NPIS early in complex overdose presentations. This observational study (US-based, retrospective cohort) cannot prove causality, but the direction of effect is consistent with clinical expectation.

PE / CHEST PAIN CHANGE THIS MONTH

Outpatient PE Management with DOACs: Very Low 30-Day Mortality for sPESI 0-1 (n=6,427)

Dore M, Duffy R. Acad Emerg Med. 2026. PMID: 42313763. pubmed.ncbi.nlm.nih.gov/42313763

In this large retrospective cohort (n=6,427 acute PE patients, US VA system), those with sPESI 0 or 1 who were treated with DOACs had very low 30-day mortality, and hospitalisation did not appear to improve outcomes compared with outpatient management. The data supports expanded outpatient management for haemodynamically stable, low-risk PE.

Limitation & UK applicability: US VA system retrospective data — younger, predominantly male population, single healthcare system. However, direction of effect is consistent with NICE NG158 and existing UK outpatient PE pathways. Key point: sPESI ≤1 is the validated triage tool; apply alongside NICE criteria, access to anticoagulant counselling, and social suitability for discharge. Not applicable to massive or submassive PE.

SECTION 2 — GUIDELINES & UK UPDATES

NHS ENGLAND UK SPECIFIC ACTION REQUIRED

NHS England Winter Planning 2026/27: Corridor Care Named a Patient Safety Priority — Action Required Before October

NHS England Chief Operating Officer Sarah-Jane Marsh CBE. NHS England, 17 July 2026. england.nhs.uk/long-read/winter-planning-2026-27

NHS England's winter 2026/27 planning letter sets out the most explicit framing yet of corridor care as a patient safety priority — not just a performance metric. Key ED-relevant requirements:

• Trusts must implement Model Emergency Department requirements ahead of winter — with corridor care elimination framed as mandatory, not aspirational.
• Ambulance handover: 15-minute handovers expected; none exceeding 45 minutes (enforced target).
• Organisational winter plans due end of August; board assurance statements due 30 September 2026.
• OPEL escalation framework to run 7 days/week from ICB coordination centres.

RCEM response (17 Jul): Dr Ian Higginson welcomed the early planning timeline and explicit corridor care framing, but described RCEM as "sceptical" that the letter would "move the dial" without tackling discharge flow. "Last winter may have looked better on paper, but didn't feel like that to our exhausted teams." Read at: rcem.ac.uk

UK SPECIFIC TRAINING & WORKFORCE

RCEM: Corridor Care is Actively Damaging EM Training Quality — GMC Survey 2026

RCEM, 23 July 2026. rcem.ac.uk | RCEM Dean Professor Simon Carley.

The GMC's 2026 National Training Survey results, published this week, show that corridor care is directly impacting the quality of emergency medicine training — undermining supervision, reducing exposure to appropriately managed cases, and increasing trainee stress. RCEM Dean Professor Simon Carley called for urgent action to protect the training environment.

Clinical & systemic significance: Trainees working in corridor-care environments cannot be appropriately supervised on complex resus cases. ARCP documentation may become increasingly difficult to complete if supervised clinical learning events are compromised. This has pipeline implications for the UK EM workforce. Raise at departmental governance and educational supervisor meetings.

UK SPECIFIC SYSTEM

570,957 Delayed Discharge Incidents in 2025/26 — Age UK Report, RCEM Responds

Age UK Parliamentary Briefing, 22 July 2026. RCEM response: rcem.ac.uk

Age UK reported 570,957 delayed discharge incidents in 2025/26, up nearly 70% in five years. RCEM President Dr Ian Higginson described this as "horrifying, and a source of shame" — linking delayed discharge and exit block directly to corridor care and ED overcrowding. The data reinforces that ED crowding is a whole-system failure requiring a whole-system response.

SAFETY MHRA

MHRA EL(26)A/35 — Xaggitin XL (Methylphenidate) Schedule 2 Controlled Drug: Incorrect Tablet Counts

MHRA, 20 July 2026. Class 4 defect. GOV.UK alert

SAFETY ALERT — CONTROLLED DRUG Drug: Xaggitin XL Prolonged-Release Tablets (methylphenidate) 27 mg, 36 mg, and 54 mg strengths — several batches. Manufacturer: Macarthys Laboratories Ltd T/A Martindale Pharma. Issue: Incorrect tablet counts (missing or extra tablets) found in packs. As a Schedule 2 Controlled Drug, this creates reconciliation discrepancies. Tablet quality itself is not affected; this is a packaging defect only. Action required: Pharmacies and GP practices should physically count tablets on receipt and at each dispensing. The product is not recalled. ED relevance: If patients present claiming missing doses of controlled ADHD medication, check whether their prescriber/pharmacy has received this batch and advise them to contact their pharmacy.

NICE UK SPECIFIC SEPSIS

NICE Sepsis Update (Procalcitonin — GID-NG10467) Delayed to 11 September 2026

NICE in-development page. nice.org.uk/guidance/indevelopment/gid-ng10467

The anticipated NICE update to NG253 adding procalcitonin testing to the sepsis pathway has been delayed again — now expected 11 September 2026 (previously projected for July 2026). Current guidance remains NG253 (November 2025). No change to current sepsis pathway. NHS England Sepsis Modern Service Framework (published 14 July 2026) remains in effect.

SECTION 3 — PAEDIATRIC EMERGENCY MEDICINE

PEM CHANGE THIS MONTH

High-Dose Intranasal Midazolam (0.5 mg/kg) Reduces Need for Rescue Sedation in Paediatric ED — Without Increased Adverse Events

JournalFeed Article-a-Day, 22 July 2026. Based on RCT: Intranasal midazolam high-dose vs low-dose, paediatric ED. Published July 2026. journalfeed.org

Study: Randomised trial comparing intranasal midazolam 0.5 mg/kg (high-dose) versus 0.2 mg/kg (low-dose) for minimal sedation in children undergoing procedures in the paediatric ED. Primary outcome: need for additional sedative medication.

• ↓ Rescue LESS ADDITIONAL SEDATIVE NEEDED
• Safe NO INCREASED AES OR ED LOS
• 0.5 MG/KG RECOMMENDED DOSE

Bottom line: Higher-dose intranasal midazolam (0.5 mg/kg, max dose per local paediatric guidance) is more effective for minimal procedural sedation in children than the lower 0.2 mg/kg dose, without any increase in adverse events or ED length of stay. This supports updating default intranasal midazolam dosing protocols in paediatric EDs.

UK / FRCEM context: Check local paediatric formulary maximum doses before change. The BNFC maximum for procedural sedation via nasal route is typically up to 0.5 mg/kg (max 10 mg). Intranasal delivery using a mucosal atomisation device (MAD) is standard in most UK children's EDs. Always have resuscitation equipment and reversal (flumazenil) available. This is not a sedation-only intervention — appropriate monitoring and documentation of sedation score required.

PEM ABDOMINAL

Intussusception: Age >48 Months, Symptoms >48 Hours, Constipation + US Wall Thickening Predict Hydrostatic Reduction Failure (n=231)

Xiong J et al. BMC Pediatr. 2026. PMID: 42304311. pubmed.ncbi.nlm.nih.gov/42304311

Study: Retrospective cohort of 231 children with ileocolic intussusception who underwent hydrostatic reduction. The study identified clinical and ultrasound predictors of reduction failure (requiring surgical intervention).

Failure predictors identified:

• Age >48 months (older children more likely to have pathological lead point)
• Symptom duration >48 hours
• Constipation as a presenting feature
• Bowel wall thickening on ultrasound

Bottom line: When two or more of these predictors are present in a child with intussusception, the index of suspicion for hydrostatic reduction failure should be higher, and earlier paediatric surgical review is appropriate alongside — not after — the first reduction attempt.

UK / FRCEM context: Intussusception is a paediatric surgical emergency. UK standard is ultrasound-guided saline or pneumatic (air) enema reduction with surgical standby. Absolute contraindications to any reduction attempt: peritonitis, perforation, shock. Retrospective cohort design means these predictors are hypothesis-generating — apply clinical judgement. The key message is: do not delay surgical involvement when multiple risk factors are present. Success rate drops with each hour of delay.

PEM SEPSIS

Base Deficit and Alactic Base Excess Outperform Lactate Alone for Early Shock Prediction in Paediatric Sepsis (n=44)

Assaad A et al. BMC Pediatr. 2026. PMID: 42304271. pubmed.ncbi.nlm.nih.gov/42304271

This retrospective cohort (n=44 paediatric sepsis patients) found that base deficit and alactic base excess (which separates the lactic acid component of base deficit) showed superior discriminative performance compared with lactate alone for predicting progression to septic shock. These two markers may be useful early warning signals when initial lactate is borderline.

Limitation and framing: Very small (n=44) single-centre retrospective study — treat as hypothesis-generating only. In standard UK ED blood gas analysis, base deficit is routinely reported. The practical insight: in paediatric sepsis, if lactate is <2 mmol/L but base deficit is significant (<-4), do not be falsely reassured — consider further assessment and earlier escalation. This does not change the Sepsis 6 or NICE NG139 pathway.

SECTION 4 — FOAMED & CRITICAL APPRAISAL

JOURNALFEED CHANGE THIS MONTH CHEST PAIN

Troponin 0/1-Hour Pathway Non-Inferior to 0/3-Hour for Safety of Discharge — JournalFeed Article of the Day

JournalFeed Article-a-Day, 23 July 2026. Primary paper in press (RCT, institution not named — follow link for PMID). journalfeed.org

JournalFeed Spoon Feed: "The European Society of Cardiology (ESC) 0/1 hour accelerated diagnostic pathway (ADP) was non-inferior to the 0/3 hour pathway for safety of discharge. Although there was no increase in patients discharged within 4 hours, median length of stay decreased."

Bottom line: The ESC 0/1 hour pathway (using high-sensitivity troponin at baseline and 1 hour) is at least as safe as the 0/3 hour pathway for ruling out NSTEMI prior to discharge. It also reduces overall ED length of stay without increasing missed NSTEMI events. This supports moving to 0/1 hr where local assay is validated for 1-hour protocol (Roche Elecsys hs-cTnT or Abbott ARCHITECT hs-cTnI).

UK context: NICE recommends high-sensitivity troponin pathways (NG185); the 0/1 hr protocol requires a locally validated assay and pre-specified cut-offs. Check your trust's current pathway — many UK EDs are already on 0/1 hr or equivalent. The key message: if your department is still on 0/3 hr due to caution, the evidence for moving to 0/1 hr continues to strengthen.

EMCRIT CRITICAL CARE

EMCrit RACC-Lit Review July 2026 + RUSH 2.0: The iRUSH and CRUSH Exams

Scott Weingart MD, EMCrit. Published 17 July 2026. emcrit.org/emcrit/racc-lit-2026-july | RUSH 2.0: emcrit.org/emcrit/429

The July EMCrit RACC-Lit review curates the key resuscitation and acute critical care literature for the month. Separately, EMCrit 429 introduces RUSH 2.0 (iRUSH — Interface-Informed RUSH) and CRUSH exams, which extend the RUSH protocol from its original crash/crashing-patient indication to a broader bedside hemodynamic assessment tool based on the four-interface hemodynamic model. The I-RUSH exam translates the physiological framework of interface hemodynamics (CO, preload, afterload, fluid tolerance) into a systematic POCUS sequence.

Clinical context: The standard RUSH exam (Pump / Tank / Pipes) remains valid for initial crashing-patient assessment. The iRUSH update adds a structured approach for undifferentiated shock phenotyping in patients who are not yet crashing. UK EM consultants with POCUS competency may find this useful for resus bay hemodynamic profiling. The CRUSH exam focuses on cardiac and aortic pathology. Full details at emcrit.org/emcrit/429.

SGEM PEM RESPIRATORY

SGEM#515: Azithromycin Does Not Reduce Wheeze Duration in Preschool Children with Acute Viral Wheeze

The Skeptics Guide to Emergency Medicine, episode 515. Published 18 July 2026. thesgem.com

SGEM #515 reviews a paediatric RCT examining whether azithromycin reduces the duration of wheeze in preschool children with acute viral respiratory illness. The conclusion: azithromycin does not shorten wheeze duration and its use in this setting should not be routine. This aligns with UK antimicrobial stewardship guidance — azithromycin should not be given for viral wheeze presentations in pre-school children presenting to ED.

SECTION 5 — QUICK HITS

YVETTE COOPER APPOINTED SECRETARY OF STATE FOR HEALTH AND SOCIAL CARE

RCEM, 20 July 2026. rcem.ac.uk

RCEM President Dr Ian Higginson welcomed the appointment of Yvette Cooper MP as the new Secretary of State for Health and Social Care, calling for urgent engagement on ED capacity, delayed discharge, and workforce issues.

AI-ASSISTED PAEDIATRIC PNEUMONIA DETECTION ON LUNG ULTRASOUND — FEASIBILITY STUDY

Ultrasound Q. 2026. JournalFeed POCUS Speed Read.

An automated AI system for detection of paediatric pneumonia on point-of-care lung ultrasound showed feasibility in preliminary data. Not yet validated for clinical use in UK EDs — treat as a research direction. Continue using conventional B-line and consolidation assessment criteria.

WALES A&E CRISIS: RCEM CALLS FOR URGENT WELSH GOVERNMENT ACTION

RCEM, 23 July 2026. rcem.ac.uk

RCEM highlighted a year-round A&E crisis in Wales — not a seasonal winter phenomenon. Waiting times for a four-hour standard breach remain worse in Wales than England. Welsh Government asked to commit to equivalent standards and resource as set out in NHS England's Model ED requirements.

MHRA CLASS 4 DEFECT: TUZULBY PROLONGED-RELEASE CHEWABLE TABLETS — MISSING PATIENT INFORMATION

MHRA EL(26)A/36, 23 July 2026. gov.uk/drug-device-alerts

Tuzulby prolonged-release chewable tablets (20/30/40mg) — missing safety information in the Patient Information Leaflet (PIL) and SmPC for certain batches (Neuraxpharm UK Ltd). No immediate ED relevance — awareness and pharmacy notification only.

NICE SEPSIS UPDATE (GID-NG10467 — PROCALCITONIN) DELAYED: NOW EXPECTED 11 SEPTEMBER 2026

NICE, July 2026. nice.org.uk

The NICE update adding procalcitonin testing guidance to NG253 (sepsis) has again been delayed. No change to the current NG253 Sepsis pathway. Continue standard NICE Sepsis 6 and National Early Warning Score (NEWS2) pathways.

EM EVIDENCE RUNDOWN — CORE REVISION — ISSUE 22

Sinus Tachycardia: Causes

A first-principles map from physiology to the bedside — FRCEM & FRCA edition

Goal: oxygen delivery must meet oxygen demand DO₂ ≥ VO₂ and maintain perfusion MAP = CO × SVR — If goal is NOT met → sinus tachycardia is the fastest compensation available.

SUPPLY ↓ DO₂

DO₂ = CO × CaO₂

CO = HR × SV SV ∝ preload × contractility ÷ afterload CaO₂ = 1.34 × Hb × SaO₂ + 0.003 × PaO₂

SAO₂ ↓

hypoxaemia

Pneumonia, pulmonary oedema, PE, asthma/COPD exacerbation, pneumothorax, V/Q mismatch

DEMAND ↑ VO₂

VO₂ = CO × (CaO₂ − CvO₂)

(Fick Principle)

FEVER

+10%/°c

Every 1°C rise in temperature increases VO₂ ~10%; sepsis, infection, thyroid storm, NMS, malignant hyperthermia

PAIN / ANXIETY

sns activation

Sympathetic surges from acute pain, anxiety disorders, panic, amphetamines, cocaine, caffeine

METABOLIC ↑

catecholamines

Hyperthyroidism, thyroid storm, phaeochromocytoma, carcinoid syndrome, stimulant drugs

EXERTION

muscle demand

Acute exercise, agitation, status epilepticus (ongoing convulsive activity), post-ictal

PREGNANCY

physiological

Increased CO requirement, anaemia, and autonomic shifts in all trimesters; resting tachycardia up to ~110 normal in late pregnancy

PERFUSION — MAP = CO × SVR

MAP ↓ → baroreceptor reflex → ↑ HR

• SVR ↓ vasodilation
• Sepsis, anaphylaxis, neurogenic shock, epidural/spinal, hepatic failure (vasodilatory state), ACE inhibitor/ARB effect

CO ↓

pump failure

Cardiogenic shock (STEMI, acute MR/AR, myocarditis), massive PE obstructive shock, cardiac tamponade

Sympathetic reflex: ↑HR + ↑SVR

HYPOVOLAEMIA

↓ preload

Haemorrhage (trauma, GI bleed, ectopic), dehydration (DKA, HHS, Addisonian crisis, VBG), third-spacing (pancreatitis, burns)

OBSTRUCTIVE

↓ filling

Tension pneumothorax, massive PE, cardiac tamponade — all impair venous return or RV/LV outflow

FRCEM / ED Application: Before treating sinus tachycardia, always ask: "Is this HR appropriate or inappropriate?" Treating an appropriate sinus tachycardia with rate control agents (bisoprolol, diltiazem) is potentially harmful — you are blocking the body's only compensatory mechanism. Identify and treat the underlying cause first. The rate will normalise. The exception: when the tachycardia itself is causing haemodynamic compromise (very rarely — usually HR >170 bpm) or worsening myocardial ischaemia in a demand-supply mismatch. Always examine, get a VBG and lactate, and think through Supply / Demand / Perfusion before reaching for a rate-control drug.

EM Evidence Rundown — Core Revision — Issue 22 · emevidence.org

FRCEM REVISION

Sources: SquigglyLines (first-principles framework) · LITFL (ECG library & causes reference) · EMCrit IBCC (haemodynamic physiology)

SECTION 6 — ACTION POINTS

• ESBL UTI step-down: Discuss with your local microbiology team whether oral fosfomycin is available and susceptibility-tested for ESBL complicated UTI patients who are improving on IV therapy. Identify patients appropriate for early oral switch and discharge.
• YEARS in cancer PE: Apply YEARS algorithm (haemoptysis, PE most likely, clinical DVT; D-dimer thresholds 500/1000 ng/mL) to haemodynamically stable cancer patients with suspected PE. If all three YEARS items negative and D-dimer <1000, CTPA can be safely withheld. Document clearly in notes.
• Intranasal midazolam dosing: Review your department's default dose for paediatric procedural sedation. Evidence supports 0.5 mg/kg via MAD device (check BNFC and local policy for max dose). Lower doses (0.2 mg/kg) result in more rescue sedation events.
• Intussusception risk stratification: When a child presents with intussusception, note duration (>48 hr), age (>48 months), constipation, and US bowel wall thickening. ≥2 predictors = higher failure risk. Ensure surgical team aware before reduction attempt rather than as rescue after failure.
• MHRA controlled drug alert: Alert pharmacy and ward staff to EL(26)A/35 — Xaggitin XL (methylphenidate) incorrect tablet counts. If patients present claiming missing ADHD medication, document, advise pharmacy contact, and do not prescribe additional supply without pharmacy verification.
• Corridor care training impact: Document any instances where corridor care compromises clinical supervision or learning events. These should be escalated through educational supervisor channels and clinical governance, not just accepted as normal. This is the evidence base for systemic change.
• Sinus tachycardia — before rate-control: Systematically exclude Supply, Demand, and Perfusion causes before considering rate-control agents. Always check for drugs that may mask tachycardia (β-blockers, rate-limiting CCBs) in patients who appear normocardic despite haemodynamic compromise.
• Winter plan: Know your trust's winter planning lead and Model ED implementation timeline. Board assurance statements due 30 September 2026. OPEL framework must run 7 days/week. Ambulance handover must not exceed 45 minutes.

TRIALS TO WATCH

NEAR TERM (Q3 2026 — DUE BEFORE OCTOBER)

ARREST-2

Lidocaine vs amiodarone vs placebo for refractory VF/pulseless VT in OHCA — follow-up publication expected Q3 2026.

2026–2027 HORIZON

LONGER HORIZON (>2027)

EM Evidence Rundown — Issue 22 — 24 July 2026 Curated by Jake Turner, Senior Registrar in Emergency Medicine (ST6). Curated with the assistance of AI (Perplexity). All content editorially reviewed. Published by EM Evidence — emevidence.org

This newsletter is for educational purposes only and does not constitute clinical advice. Always apply clinical judgement and follow local guidelines. Individual items represent the editorial view of the author and are based on evidence current at time of publication. Links verified at time of publication — check primary sources before acting on data. To unsubscribe or provide feedback: emevidence.org