cardio.hypertensive-emergency.autonomic-dysreflexia.v1

Autonomic dysreflexia (SCI ≥T6; remove trigger FIRST, short-acting titratable drugs second)

cardiologyacuteadultacuteinpatienttransitionoutpatient

Start encounter →Print handoutPRODUCTION

Phase E variant of cardio.hypertensive-emergency.core.v1 — narrowed to autonomic dysreflexia (AD), the spinal-cord-injury (≥T6) paroxysmal hypertensive crisis driven by an uncontrolled splanchnic sympathetic reflex to a noxious stimulus below the lesion. Defining feature: the crisis is relative to the patient's LOW SCI baseline (resting SBP often 90-110 mmHg) so absolute thresholds (180/120) under-detect it; reflex bradycardia + above-lesion flushing/sweating/headache with below-lesion pallor/piloerection are characteristic. KEY DIFFERENCES FROM PARENT: trigger removal is PRIMARY therapy (sit upright, lower legs, loosen constrictors, then bladder → bowel → skin search; bladder over-distension causes ~75-85%). Pharmacotherapy is a temporising BRIDGE using RAPID-ONSET SHORT-ACTING TITRATABLE agents (GTN, IR nifedipine bite-and-swallow, captopril SL, IV labetalol/nitroprusside) — this INVERTS the generic gradual ≤25%/h reduction rule because BP collapses abruptly when the trigger is relieved (overshoot risk with long-acting agents). NITRATES ABSOLUTELY CONTRAINDICATED if a PDE5 inhibitor was taken within 24 h (sildenafil/vardenafil) or 48 h (tadalafil) — very common in the SCI population. End-organ targets: hypertensive ICH/PRES/seizure, MI, pulmonary oedema, retinal detachment; labour-triggered AD in SCI women mimics/overlaps eclampsia. Manifest pointer reuses cardio.hypertensive-emergency.core.v1 manifest. Design-brief pointer reuses parent (AD-specific differences documented inline). Recurrence prevention (bladder/bowel programme, pre-procedure prophylaxis, AD wallet card) is integral, not optional. Status INTEGRATED. Authored 2026-05-15 by shard-06-cardio-acute as autonomic-dysreflexia hypertensive-emergency variant. Sister-differentiated from core, phaeochromocytoma-crisis, and eclampsia.

Entry points (6)

symptom
Sudden severe pounding headache + flushing/sweating ABOVE the lesion ± nasal congestion in a known SCI patient — classic autonomic dysreflexia until proven otherwise
pounding_headache_with_sweating_above_lesion_in_sci_patient
vital_abnormality
Paroxysmal SBP rise ≥20-40 mmHg above the patient's SCI baseline (baseline often only 90-110 mmHg) ± reflex bradycardia — AD crisis even if absolute SBP looks "only" 150-160
paroxysmal_sbp_rise_20_to_40_above_sci_baseline
history
Spinal cord injury at or above T6 presenting with new hypertensive symptoms — anatomic substrate for AD (splanchnic outflow above lesion uncontrolled)
sci_at_or_above_t6_with_new_hypertensive_symptoms
symptom
Blurred vision, apprehension, piloerection and cool pale skin BELOW the lesion in an SCI patient — sympathetic over-discharge below + parasympathetic flushing above
blurred_vision_anxiety_piloerection_below_lesion
problem_list
Documented recurrent AD episodes (often catheter blockage or bowel programme failure) — chronic trigger-prevention pathway
recurrent_autonomic_dysreflexia_episodes
vital_abnormality
Severe hypertension developing during cystoscopy, urodynamics, bowel care or labour in an SCI patient — procedure-triggered AD
severe_hypertension_during_sci_bladder_or_bowel_procedure

Required inputs (11)

agerequired
demographic • used at CONTEXT
Older SCI patients have stiffer vasculature + higher stroke/ICH risk during AD surges; influences urgency of pharmacologic control
sexrequired
demographic • used at CONTEXT
Female SCI patients: AD can be triggered by labour/delivery and mimic eclampsia; reproductive planning relevant
level_and_completeness_of_spinal_cord_injuryrequired
history • used at FRAME
AD requires a lesion at/above ~T6; completeness (AIS grade) and chronicity (AD typically emerges >1 month post-injury) calibrate pretest probability
patient_known_sci_resting_blood_pressure_baselinerequired
history • used at ENTRY
SCI resting SBP is frequently 90-110 mmHg; the crisis is defined relative to that baseline, not the general-population 180/120 threshold
pde5_inhibitor_use_within_24_to_48hrequired
history • used at RED_FLAGS
Sildenafil/vardenafil within 24 h or tadalafil within 48 h ABSOLUTELY contraindicates nitrates — drives drug-class selection toward CCB/alpha-blocker
headacherequired
symptom • used at ENTRY
Pounding headache is the cardinal AD symptom and a marker of cerebral hypertensive stress; abrupt change warrants escalation
blood_pressurerequired
vital • used at ENTRY
Serial BP every 2-5 min during the episode drives titration and the trigger-removal response curve
heart_raterequired
vital • used at ENTRY
Baroreceptor-mediated reflex bradycardia is characteristic; tachycardia should prompt reconsideration of the diagnosis (e.g., pain, PE, thyroid storm)
bladder_drainage_status_and_last_bowel_carerequired
history • used at INITIAL_WORKUP
Bladder over-distension (blocked/kinked catheter) causes ~75-85% of AD; faecal impaction is second — directs the trigger search immediately
urinalysis
lab • used at BRANCHING_WORKUP
UTI is a common AD trigger; pyuria/nitrites direct antimicrobial therapy as part of definitive trigger control
pregnancy_status
history • used at CONTEXT
Labour-triggered AD in SCI women mimics and coexists with pre-eclampsia/eclampsia; MFM co-management and magnesium decisions differ

12-phase flow (11)

1FRAME
Autonomic dysreflexia = noxious stimulus below an SCI lesion at/above T6 → uncontrolled splanchnic sympathetic surge → paroxysmal severe HTN + reflex bradycardia. The crisis is defined relative to the patient's low SCI baseline. Trigger removal is the primary therapy; drugs are a temporising bridge
inputs: level_and_completeness_of_spinal_cord_injury
advance: AD phenotype framed against SCI baseline
2ENTRY
Immediate non-pharmacologic bundle: sit fully upright, lower legs, loosen constrictive clothing/binders/leg-bag straps. Serial BP + HR every 2-5 min. Document symptoms above (headache, flushing, sweating, congestion) vs below (pallor, piloerection) the lesion
inputs: headache, blood_pressure, heart_rate, patient_known_sci_resting_blood_pressure_baseline
advance: positioning bundle applied + serial BP monitoring established
3CONTEXT
SCI level/completeness/chronicity, prior AD episodes and usual triggers, bladder/bowel programme, current medications (especially PDE5 inhibitors, alpha-blockers, antihypertensives), pregnancy status, recent procedures
inputs: age, sex
advance: context complete
4RED_FLAGS
Hypertensive ICH / encephalopathy / PRES / seizure, retinal detachment, myocardial ischaemia, pulmonary oedema; PDE5-inhibitor use (nitrate contraindication); pregnancy/labour-triggered AD mimicking eclampsia; sustained SBP despite trigger removal (atypical AD vs alternative diagnosis)
inputs: pde5_inhibitor_use_within_24_to_48h
actions: htn_emergency
advance: catastrophic end-organ + drug-safety screen complete
5INITIAL_WORKUP
TRIGGER HUNT (in order of frequency): (1) bladder — check catheter for kinks/blockage; if indwelling, irrigate gently or replace; if no catheter, catheterise with 2% lidocaine gel; (2) bowel — gentle digital rectal exam with topical anaesthetic for impaction AFTER BP partly controlled; (3) skin — inspect for pressure injury, tight straps, ingrown toenail; (4) other — fracture, DVT, acute abdomen, ingrown nail. ECG for ischaemia/arrhythmia during surge
inputs: bladder_drainage_status_and_last_bowel_care
actions: panel.cardiac
advance: systematic trigger search initiated
6BRANCHING_WORKUP
Targeted to suspected trigger: urinalysis + culture (UTI), KUB/bladder scan (retention/stones), abdominal imaging (acute abdomen), Doppler (DVT), X-ray (occult fracture). Neuro-imaging (CT/MRI brain) if focal deficit, seizure, or thunderclap headache to exclude ICH/PRES
inputs: urinalysis
actions: panel.renal
advance: trigger localised or dangerous mimics excluded
7RISK_STRATIFICATION
MAP trend vs SCI baseline; symptomatic vs asymptomatic; presence of end-organ injury; pregnancy; recurrence pattern. Persistent SBP ≥150 with symptoms despite positioning = pharmacotherapy indicated. Refractory AD after thorough trigger removal → escalate monitored setting + reconsider diagnosis
inputs: blood_pressure
actions: calc.map
advance: severity + pharmacotherapy threshold decided
8TREATMENT
If SBP persistently ≥150 (or symptomatic) WHILE trigger is being removed: rapid-onset SHORT-ACTING titratable agent — GTN spray/paste (NOT if PDE5i within 24-48 h), immediate-release nifedipine 10 mg bite-and-swallow, or captopril 25 mg SL; escalate to IV labetalol or sodium nitroprusside in a monitored setting for refractory/severe surges. Re-check BP every 2-5 min; STOP the agent the moment the trigger is relieved to avoid overshoot hypotension. Definitive therapy = trigger eradication (unblock/replace catheter, disimpact, treat UTI, offload pressure injury)
inputs: pde5_inhibitor_use_within_24_to_48h
advance: BP controlled toward SCI baseline + trigger definitively removed
9DISPOSITION
Most single self-limited episodes with an identified, reversed trigger and resolved symptoms can be observed then discharged with prevention counselling. Admit if: end-organ injury, refractory/recurrent AD, unclear trigger, pregnancy/labour, or need for procedural trigger management
advance: disposition decision documented
10MONITORING
Post-resolution BP monitoring ≥2 h (rebound or overshoot risk, especially if long-acting agent inadvertently used or trigger only partially relieved); neuro checks if any surge symptoms; reassess bladder/bowel programme adequacy
actions: panel.cardiac
advance: post-episode monitoring window completed without rebound
11FOLLOWUP
SCI/rehab + urology co-management: optimise bladder programme (catheter type/schedule, treat detrusor overactivity), bowel programme, skin surveillance. Provide written AD emergency protocol + wallet card; pre-procedure AD prophylaxis plan (prophylactic nifedipine or topical anaesthetic before cystoscopy/colonoscopy/urodynamics); pregnancy AD plan with MFM if applicable; educate caregivers
advance: recurrence-prevention plan + patient/caregiver education + procedural prophylaxis documented