12-phase flow (12)

1. 1FRAME
   Frame as an AIRWAY EMERGENCY first, an infection second. Adult disease now outnumbers paediatric post-Hib-vaccine and is more often missed; paediatric disease is the do-NOT-agitate / OR-controlled-intubation scenario (Sideris Laryngoscope 2020 PMID 31173373; McVernon Epidemiol Infect 2005 PMID 16288684). Sepsis, abscess source-control surgery, deep-neck source control, and the primary anaphylaxis/angioedema pathway are recognised then routed OUT by engine_id; this engine OWNS recognition, the controlled-airway pathway, IV antibiotic + adjunct selection, and ICU disposition.
   advance: epiglottitis scope confirmed; sepsis / abscess-surgery / angioedema concerns routed by engine_id
2. 2ENTRY
   Recognise the cardinal presentation — rapid severe sore throat + odynophagia out of proportion to a near-normal oropharynx, muffled "hot-potato" voice — and immediately gauge whether the patient looks toxic or is posturing to protect the airway. This is the fastest pivot away from "simple pharyngitis".
   inputs: odynophagia_out_of_proportion, voice_quality_muffled_hot_potato
   advance: entry trigger present; odynophagia-out-of-proportion + voice quality + first-look toxicity recorded
3. 3CONTEXT
   Age band (paediatric do-not-agitate vs adult subacute/missed), fever (infective vs angioedema/foreign-body), diabetes and immunocompromise (hard airway-intervention predictors + atypical/fungal microbiology), Hib status, ACE-inhibitor/allergen/C1-INH-deficiency (angioedema pivot), pregnancy. This phase assigns the pre-test airway-risk prior and the look-alike priors.
   inputs: age_band_pediatric_vs_adult, temperature, diabetes_mellitus, immunocompromise, angioedema_anaphylaxis_risk_ace_inhibitor_or_allergen, hib_immunisation_status
   actions: workup.airway_distress
   advance: age + comorbidity + look-alike priors assigned; do-not-agitate flag set if paediatric
4. 4RED_FLAGS
   IMPENDING-OBSTRUCTION screen: stridor, drooling/secretion pooling, tripod/sniffing posture, refusal to lie flat, accelerating distress, hypoxia (a LATE sign). In a CHILD: do NOT use a tongue depressor, do NOT cannulate or distress the child, do NOT lie supine — keep calm with a parent, give blow-by O2, and move to the OR with the most experienced airway operator + ENT scrubbed for a surgical airway. Toxic/hypotensive → recognise septic supraglottitis and route OUT to id.sepsis.core.v1 while securing the airway. Do NOT delay the airway for imaging or labs.
   inputs: drooling_inability_to_handle_secretions, stridor_or_respiratory_distress, tripod_or_sniffing_posture_unable_to_lie_flat, spo2_and_work_of_breathing, sbp
   actions: workup.airway_distress, workup.anaphylaxis, calc.qsofa, calc.news2, protocol.septic_shock
   advance: airway-obstruction red flags screened; controlled-airway pathway activated if positive; sepsis routed by engine_id if toxic
5. 5INITIAL_WORKUP
   ONLY if the airway is stable and not at the expense of definitive airway management: CBC + CRP + glucose (CRP > 100 mg/L, hyperglycaemia, neutrophilia mark the high-risk phenotype — Shapira Galitz Laryngoscope 2017 PMID 28493349; Vaid Am J Otolaryngol 2021 PMID 34044211); blood cultures before antibiotics. Start empiric IV antibiotics early — early antibiotics are associated with lower intubation (O'Brien Acad Emerg Med 2026 PMID 42023439). In a compromised airway, securing the airway PRECEDES all workup.
   inputs: crp, wbc_with_differential, blood_glucose
   actions: panel.cbc, panel.inflammation, panel.cmp, calc.sirs
   advance: airway stable AND baseline labs/cultures sent; OR airway secured first and labs deferred
6. 6BRANCHING_WORKUP
   Definitive visualisation is the diagnostic key: gentle flexible fibreoptic laryngoscopy by an airway-capable clinician (in a setting ready to convert to a definitive airway). Lateral neck X-ray "thumbprint sign" supports the diagnosis but a negative film does NOT exclude it (Bridwell Am J Emerg Med 2022 PMID 35489220). Contrast neck CT only if the airway is safe and an epiglottic abscess / deep-neck extension is suspected (abscess → source-control + strong airway-intervention predictor). Branch: abscess → drainage + route consideration; deep-neck extension → ent.deep-neck-space-infection.core.v1; angioedema picture → anaphylaxis/angioedema pathway; foreign-body history → bronchoscopy pathway.
   inputs: lateral_neck_radiograph_or_fibreoptic_laryngoscopy, contrast_neck_ct_if_abscess_suspected_and_airway_safe, blood_and_epiglottic_cultures
   actions: workup.airway_distress, workup.cellulitis_necfasc, workup.acute_headache
   advance: epiglottitis confirmed on visualisation/imaging OR an alternative look-alike assigned and routed by engine_id
7. 7DIFFERENTIAL
   Terminal differential with named pivots: epiglottitis/supraglottitis (rapid severe odynophagia out of proportion + muffled voice + drooling + minimal oropharyngeal findings + thumbprint pivot) vs croup (age 6 mo-3 y + barking cough + viral prodrome + gradual + steeple-sign pivot) vs peritonsillar abscess (trismus + unilateral bulge + uvular deviation pivot) vs retropharyngeal abscess (neck stiffness/extension refusal + retropharyngeal widening pivot) vs bacterial tracheitis (toxic + brassy cough + thick tracheal pus + croup-non-responsive pivot) vs anaphylaxis/angioedema (urticaria/allergen or ACE-I/C1-INH + lip-tongue swelling + faster tempo + afebrile pivot) vs inhaled/ingested foreign body (witnessed choking + sudden + afebrile pivot).
   actions: workup.bacterial_meningitis
   advance: single best diagnosis selected; airway look-alike explicitly excluded or routed
8. 8RISK_STRATIFICATION
   Airway-intervention risk: epiglottic abscess, stridor, and diabetes are the strongest predictors (Sideris Laryngoscope 2020 PMID 31173373 — abscess RR ≈ 2.45, stridor RR ≈ 7.15, diabetes RR ≈ 2.15); add the Shapira Galitz high-risk phenotype (male, dyspnoea, epiglottic+aryepiglottic oedema, ↑CRP, hyperglycaemia, recurrence) and O'Brien predictors (older age, comorbidity, hypoxia). qSOFA/NEWS2/SIRS escalate the septic picture out. Output: secure-airway-now vs admit-and-observe band.
   inputs: stridor_or_respiratory_distress, spo2_and_work_of_breathing, sbp, diabetes_mellitus
   actions: calc.qsofa, calc.news2, calc.sirs
   advance: airway-risk band + septic overlay assigned
9. 9TREATMENT
   AIRWAY FIRST: controlled airway in the OR/ICU with the most experienced operator, anaesthesia + ENT present, surgical-airway (tracheostomy/cricothyroidotomy) backup prepared and scrubbed (Felton West J Emerg Med 2021 PMID 34787558 — failed airways cause the deaths). Then empiric IV third-generation cephalosporin (ceftriaxone or cefotaxime) covering H. influenzae + streptococci, ADD anti-staphylococcal/anti-MRSA cover (vancomycin or clindamycin) where S. aureus/MRSA risk; ampicillin-sulbactam is an alternative. Adjuncts (DEBATED, not a substitute for the airway): single-dose IV dexamethasone and nebulised adrenaline — recent cohort data associate early steroids with lower intubation (O'Brien Acad Emerg Med 2026 PMID 42023439 — RR 0.48) but RCT-grade evidence is lacking. Antibiotic-/steroid-safety gating in pregnancy. Do NOT manage a drainable epiglottic abscess or deep-neck source with antibiotics alone — route source control.
   inputs: pregnancy, diabetes_mellitus, immunocompromise
   advance: controlled airway plan executed/declared unnecessary; empiric IV antibiotics + adjunct decision started; source control routed if abscess
10. 10DISPOSITION
    ALL suspected/confirmed epiglottitis → ICU (or equivalent high-acuity airway-observation bed) regardless of whether intubated — most do not require intervention but deterioration is fast and unpredictable (Felton West J Emerg Med 2021 PMID 34787558; Bridwell Am J Emerg Med 2022 PMID 35489220). Intubated → ICU for airway management. Septic → admit + route OUT to id.sepsis.core.v1 with carryover. Epiglottic abscess / deep-neck extension → ENT for drainage / route to ent.deep-neck-space-infection.core.v1. Discharge is NOT a disposition from the acute presentation.
    inputs: spo2_and_work_of_breathing, sbp
    advance: ICU/high-acuity airway disposition documented; septic/abscess cases admitted and routed by engine_id
11. 11MONITORING
    Continuous airway + saturation monitoring with the difficult-airway trolley and a surgical-airway kit at the bedside until the epiglottis is demonstrably resolving. Serial CRP/WBC track infective response; expect clinical improvement within 24-48 h of IV antibiotics. Extubation only when a cuff-leak and direct/endoscopic visualisation confirm supraglottic oedema has settled — failed extubation is a recognised severity trigger. Watch for evolving epiglottic abscess if no improvement at 48-72 h (Penella Eur Arch Otorhinolaryngol 2022 PMID 35396955).
    inputs: crp, wbc_with_differential
    actions: panel.inflammation
    advance: objective airway + infective improvement, OR re-evaluation/abscess/failed-extubation trigger fired
12. 12FOLLOWUP
    Post-extubation airway review and documentation of the difficult-airway event for future anaesthetic alerts. Identify and address the substrate: diabetes optimisation (a hard predictor), immunocompromise work-up if atypical/fungal/recurrent, Hib vaccination if unvaccinated and indicated. Counsel on recurrence (recurrent supraglottitis runs a more severe course — Shapira Galitz Laryngoscope 2017 PMID 28493349). ENT follow-up to confirm mucosal resolution; ACE-inhibitor cessation + allergy/immunology referral if the episode was angioedema rather than infection.
    inputs: diabetes_mellitus, hib_immunisation_status
    advance: difficult-airway alert documented; substrate-modification + recurrence-counselling + ENT follow-up plan recorded