12-phase flow (12)

1. 1FRAME
   Frame as deep fascial-neck-space infection (retropharyngeal / parapharyngeal / prevertebral / submandibular-Ludwig / masticator / parotid / carotid-sheath) by source (odontogenic, tonsillar/pharyngeal, salivary, foreign-body, IVDU). The dominant tasks are AIRWAY-FIRST recognition, CT space-mapping, broad-spectrum IV cover, and surgical source control. The controlled-airway algorithm, the localised PTA drainage ladder, the upstream pharyngitis pathway, and the sepsis bundle are routed OUT by engine_id, not re-authored here.
   advance: deep-space scope + suspected source framed; airway/PTA/pharyngitis/sepsis ownership flagged for routing by engine_id
2. 2ENTRY
   Recognise the neck-swelling-with-fever-dysphagia-trismus, Ludwig floor-of-mouth-elevation, reciprocal-routed-in-from-ENT-engine, source-driven, or CT-ring-enhancement entry; capture the suspected source up front (odontogenic vs tonsillar vs salivary vs foreign-body vs IVDU).
   inputs: floor_of_mouth_elevation_or_tongue_displacement
   actions: workup.lymphadenopathy
   advance: entry trigger present; suspected source recorded
3. 3CONTEXT
   Build the space-localisation + severity prior: floor-of-mouth elevation/tongue displacement (submandibular/Ludwig), trismus (masticator/parapharyngeal), neck stiffness/torticollis/odynophagia out of proportion (retropharyngeal-prevertebral), fever; comorbidity (diabetes, immunocompromise, IVDU). This phase assigns the pre-CT space prior and the difficult-airway prior.
   inputs: trismus_present, neck_stiffness_torticollis_dysphagia, temperature, diabetes_mellitus, immunocompromise, ivdu_or_instrumentation_or_foreign_body
   actions: workup.acute_headache
   advance: space-localisation + difficult-airway + severity prior assigned
4. 4RED_FLAGS
   Recognise the catastrophic set: airway obstruction (stridor / can't-lie-flat / drooling / floor-of-mouth elevation) → secure airway, route the controlled-airway doctrine to ent.epiglottitis.core.v1; descending necrotising mediastinitis (chest/back pain, dyspnoea, very high CRP) → cardiothoracic + thoracic drainage; Lemierre internal-jugular septic thrombophlebitis (rigors, neck-vein tenderness, septic pulmonary emboli); carotid-sheath erosion / sentinel bleed; cervical necrotising fasciitis (crepitus, dishwater discharge, pain out of proportion); systemic toxicity / qSOFA≥2 / hypotension → route to id.sepsis.core.v1. Recognised here, the disease-specific management routed OUT by engine_id.
   inputs: airway_compromise_features, chest_back_pain_dyspnoea_mediastinal, lemierre_features_neck_vein_tenderness_septic_emboli, sbp
   actions: workup.airway_distress, workup.cellulitis_necfasc, calc.qsofa, calc.news2, protocol.septic_shock
   advance: airway / mediastinitis / Lemierre / carotid-erosion / nec-fasc / sepsis screened and routed by engine_id if positive
5. 5INITIAL_WORKUP
   Targeted labs: CBC + CRP (suppuration + mediastinitis-risk + drainage-need anchor — Arslan J Investig Med 2022; Hu Medicina 2022); CMP for hydration / renal dosing in the drooling/poor-intake patient; coagulation panel if surgical drainage planned or anticoagulated; blood glucose/HbA1c to unmask diabetes. Blood + (intra-operative) deep-space aspirate cultures incl. anaerobic/Fusobacterium media; do NOT delay airway control or surgical source control for labs.
   inputs: crp, wbc_with_differential
   actions: panel.cbc, panel.inflammation, panel.cmp, panel.coag
   advance: baseline labs sent; hydration + bleeding risk assessed; airway/source-control not delayed for labs
6. 6BRANCHING_WORKUP
   Space/abscess-mapping decision tree: contrast CT neck (the 78%-used standard — Sheikh Clin Otolaryngol 2023) defines space(s), drainable collection vs phlegmon, vessel relations, and the descending track; EXTEND CT to the chest when any mediastinal feature (chest/back pain, dyspnoea, very high CRP) — retropharyngeal/anterior-visceral spread predicts DNM (Hu Medicina 2022). POCUS is an adjunct when the patient cannot lie flat (Bridwell/Long Am J Emerg Med 2020). Phlegmon without a drainable collection → IV antibiotics + observe with a low re-image threshold.
   inputs: contrast_ct_neck_to_mediastinum
   actions: workup.cellulitis_necfasc, workup.bacterial_meningitis
   advance: space map + drainable-collection vs phlegmon resolved on CT (± chest); mediastinal extension excluded or routed
7. 7DIFFERENTIAL
   Terminal differential with pivot findings: deep-neck-space abscess vs peritonsillar abscess (peritonsillar-localised bulge + uvular deviation, neck supple — route to ent.peritonsillar-abscess.core.v1) vs epiglottitis (supraglottic, near-normal oropharynx, "thumbprint" — route to ent.epiglottitis.core.v1) vs uncomplicated pharyngitis/tonsillitis (symmetric, no trismus / floor-of-mouth elevation / neck stiffness — route to ent.pharyngitis.core.v1) vs cervical lymphadenitis (discrete mobile tender node, no fascial-space tracking on CT) vs infected branchial/thyroglossal congenital cyst (longstanding cystic lesion in a typical location, recurrent, less toxic) vs cervical necrotising fasciitis (crepitus, dishwater discharge, pain out of proportion) vs Lemierre (IJ thrombus + septic emboli pivot).
   advance: single best diagnosis selected; PTA-on-deep-space and necrotising-overlap coexistence flagged
8. 8RISK_STRATIFICATION
   Severity → disposition: single-space drainable collection, protected airway, no systemic toxicity → admit for IV antibiotics ± drainage; multispace involvement, retropharyngeal/prevertebral/anterior-visceral spread, very high/rising CRP, diabetes/immunocompromise, threatened airway, qSOFA≥2/NEWS2-high → ICU + urgent surgical source control. SIRS / qSOFA / NEWS2 layered for the systemic-toxicity and mediastinitis-risk upgrade (Hu Medicina 2022; Ho Ear Nose Throat J 2023 — mediastinitis is the dominant prolonged-stay predictor).
   inputs: temperature, sbp
   actions: calc.qsofa, calc.sirs, calc.news2
   advance: severity class + ICU-vs-ward + surgical-urgency track assigned
9. 9TREATMENT
   Airway-first → source control → antimicrobial: (1) SECURE THE AIRWAY before anything else if threatened — flexible/awake fibreoptic technique with a surgical-airway backup (route the controlled-airway doctrine to ent.epiglottitis.core.v1; in Ludwig do not force supine / blind oral intubation — Dowdy Anesth Prog 2019); (2) urgent SURGICAL source control — transcervical or transoral incision-and-drainage / decompression of a drainable collection, dental source extraction, foreign-body removal (Sheikh Clin Otolaryngol 2023 — surgical drainage in ~81%; phlegmon without a collection → medical + observe); (3) IV empiric broad-spectrum anaerobe + streptococcal + MRSA cover (ampicillin-sulbactam or piperacillin-tazobactam ± vancomycin/linezolid for MRSA; clindamycin or add metronidazole for anaerobe cover; ceftriaxone-based alternative; Fusobacterium-aware); (4) the Lemierre internal-jugular-thrombosis anticoagulation branch is genuinely DEBATED — antibiotics are the mainstay, anticoagulation is case-by-case (Adedeji Ann Pharmacother 2020 — 6-12 wk if used). Antibiotic-safety gating by pregnancy/allergy/renal. Do NOT delay airway or surgical source control for antibiotics.
   inputs: anticoagulation_or_bleeding_diathesis, pregnancy
   actions: protocol.septic_shock
   advance: airway secured if threatened; drainable collection drained (or phlegmon treated medically); broad-spectrum IV started; source controlled; ENT/OMFS/thoracic engaged
10. 10DISPOSITION
    Admit all deep-neck-space infection; ICU for threatened/secured airway, mediastinitis, septic shock, multispace disease, or significant comorbidity (Charlton J Laryngol Otol 2024 — ICU ~32%, tracheostomy ~15%). Airway / descending mediastinitis / Lemierre / necrotising fasciitis / sepsis → route OUT by engine_id (ent.epiglottitis.core.v1 for the controlled airway, cardiothoracic for the mediastinum, id.sepsis.core.v1 for the bundle) with carryover (CT space map, CRP, organism, airway status).
    inputs: temperature, sbp
    advance: admission level (ward vs ICU) documented; route-out completed if airway/mediastinitis/Lemierre/sepsis positive
11. 11MONITORING
    Expect improvement within 48-72 h of adequate source control + antibiotics; persistent fever, rising CRP, new chest/back pain, or expanding neck → re-image (CT neck-to-chest) for inadequate drainage / new space / descending mediastinitis, do NOT silently extend antibiotics. Continuous airway vigilance (re-obstruction, tracheostomy decisions — Kim J Oral Maxillofac Surg 2021 favoured maintained orotracheal intubation over upfront tracheotomy). Watch for delayed Lemierre (septic pulmonary emboli) and carotid sentinel bleed.
    inputs: crp, wbc_with_differential
    actions: panel.inflammation
    advance: objective improvement by 48-72 h, OR re-imaging / re-drainage / route-out triggered
12. 12FOLLOWUP
    Definitive source eradication (dental extraction/endodontics for an odontogenic source, tonsillectomy candidacy if recurrent tonsillar source, salivary-duct management); diabetes optimisation (DM is a recurrence + complication driver — Bandol Medicina 2025); IVDU harm-reduction / addiction referral; ENT/OMFS follow-up; counsel return precautions for re-accumulation, airway, mediastinitis, and Lemierre. Anticoagulation-duration follow-up if a Lemierre IJ thrombus was treated (Adedeji Ann Pharmacother 2020 — 6-12 wk).
    inputs: diabetes_mellitus, odontogenic_or_pharyngeal_or_ivdu_or_foreign_body_source
    advance: definitive source-eradication plan + comorbidity optimisation + follow-up + return precautions documented