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cardio.hypertensive-emergency.autonomic-dysreflexia.v1PRODUCTION
cardio.hypertensive-emergency.autonomic-dysreflexia.v1

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

cardiologyacuteadult
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Detailed

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

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AD phenotype framed against SCI baseline

Patient inputs (11)

Older SCI patients have stiffer vasculature + higher stroke/ICH risk during AD surges; influences urgency of pharmacologic control

Female SCI patients: AD can be triggered by labour/delivery and mimic eclampsia; reproductive planning relevant

SCI resting SBP is frequently 90-110 mmHg; the crisis is defined relative to that baseline, not the general-population 180/120 threshold

Pounding headache is the cardinal AD symptom and a marker of cerebral hypertensive stress; abrupt change warrants escalation

Serial BP every 2-5 min during the episode drives titration and the trigger-removal response curve

Baroreceptor-mediated reflex bradycardia is characteristic; tachycardia should prompt reconsideration of the diagnosis (e.g., pain, PE, thyroid storm)

AD requires a lesion at/above ~T6; completeness (AIS grade) and chronicity (AD typically emerges >1 month post-injury) calibrate pretest probability

Bladder over-distension (blocked/kinked catheter) causes ~75-85% of AD; faecal impaction is second — directs the trigger search immediately

Sildenafil/vardenafil within 24 h or tadalafil within 48 h ABSOLUTELY contraindicates nitrates — drives drug-class selection toward CCB/alpha-blocker

UTI is a common AD trigger; pyuria/nitrites direct antimicrobial therapy as part of definitive trigger control

Labour-triggered AD in SCI women mimics and coexists with pre-eclampsia/eclampsia; MFM co-management and magnesium decisions differ

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Severity triggers (5)

5 need judgement
  • informationalseverehypertensive_ich_or_pres_or_seizure_during_ad_surge
    AD surge with focal neurological deficit, thunderclap headache, seizure, or encephalopathy — hypertensive intracerebral haemorrhage or posterior reversible encephalopathy syndrome (PRES); a leading cause of AD-related death
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverepde5_inhibitor_within_24_to_48h_nitrate_contraindicated
    SCI patient (very high background ED-treatment prevalence) took sildenafil/vardenafil within 24 h or tadalafil within 48 h — nitrate vasodilators (GTN, nitroprusside) are absolutely contraindicated due to refractory hypotension risk
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevererefractory_ad_despite_thorough_trigger_removal
    Persistent severe hypertension despite upright positioning, constrictor release, catheter management and disimpaction — atypical/occult trigger (occult fracture, acute abdomen, DVT, intra-abdominal pathology) or an alternative diagnosis (phaeochromocytoma, thyroid storm, pre-eclampsia)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverelabour_triggered_ad_in_sci_woman_eclampsia_overlap
    Pregnant SCI woman (lesion ≥T6) in labour with severe hypertension — uterine contractions are a potent AD trigger; AD coexists with and mimics pre-eclampsia/eclampsia; misclassification risks wrong therapy
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveread_related_myocardial_ischaemia_or_pulmonary_oedema
    AD surge precipitating chest pain, troponin rise, arrhythmia, or flash pulmonary oedema from acute LV afterload mismatch on the sympathetic surge
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Autonomic dysreflexia pharmacotherapy — trigger removal FIRST; short-acting titratable agents only while trigger is being relieved; nitrates contraindicated with recent PDE5 inhibitor (Consortium for Spinal Cord Medicine; 2025 ACC/AHA)
axis: autonomic_dysreflexia_short_acting_titratable_after_trigger_removal
Selected axis "Autonomic dysreflexia pharmacotherapy — trigger removal FIRST; short-acting titratable agents only while trigger is being relieved; nitrates contraindicated with recent PDE5 inhibitor (Consortium for Spinal Cord Medicine; 2025 ACC/AHA)" by default fallback (first axis)
  • Upright positioning + loosen constrictors + trigger removal (PRIMARY therapy)
    first line
    non_pharmacologic
    Sit fully upright, lower legs, loosen clothing/binders/leg-bag; unblock or replace catheter; disimpact bowel with topical anaesthetic; offload pressure injury • N/A • immediate, before drugs
    triggers: ad_episode_recognised, sbp_rising_in_sci_patient
    Consortium for Spinal Cord Medicine AD guideline — positioning + trigger eradication is definitive and resolves the majority of episodes; bladder cause in ~75-85%
  • nitroglycerin
    first line
    nitrate_vasodilator
    GTN 0.4 mg SL spray or 2% paste 1 inch to skin (wipe off once BP controlled) • SL/topical • repeat/titrate q3-5 min to SCI baseline
    triggers: symptomatic_ad_sbp_persistently_above_150_no_pde5i
    Rapid onset, easily removed (paste wiped off) for fast offset when trigger relieved — Krassioukov 2009 (PMID 19651276); ABSOLUTELY CONTRAINDICATED if PDE5 inhibitor within 24 h (sildenafil/vardenafil) or 48 h (tadalafil)
    rxcui 4917
  • nifedipine (immediate-release)
    first line
    dihydropyridine_ccb
    10 mg capsule bite-and-swallow • PO • may repeat once after 20-30 min
    triggers: symptomatic_ad_with_pde5i_use_nitrate_contraindicated, ad_in_community_or_pre_hospital_setting
    Short-acting, no nitrate interaction with PDE5i — preferred when sildenafil/tadalafil precludes GTN; bite-and-swallow (NOT sublingual) for predictable rapid absorption per AD guideline
    rxcui 7417
  • captopril
    second line
    ace_inhibitor
    25 mg sublingual/chewed • SL/PO • once; reassess in 15-20 min
    triggers: ad_refractory_to_first_agent, pde5i_use_with_ccb_intolerance
    Rapid-onset short-acting alternative; avoid if hyperkalaemia or significant CKD (SCI patients have high CKD prevalence — check eGFR)
    rxcui 1998
  • labetalol
    rescue
    alpha_beta_blocker
    10-20 mg IV over 2 min, repeat/double q10 min (max ~300 mg) in a monitored setting • IV • titrate to SCI baseline
    triggers: severe_or_refractory_ad_in_monitored_setting, ad_with_end_organ_injury
    IV titratable for refractory/severe AD with monitoring; combined alpha-beta blockade counters the sympathetic surge — ESC/ESH 2023 hypertensive-emergency framework
    rxcui 6185
  • sodium nitroprusside
    rescue
    arteriolar_venodilator
    0.3-0.5 mcg/kg/min IV, titrate (arterial-line monitored ICU) • IV • continuous, titrate to SCI baseline
    triggers: refractory_severe_ad_with_end_organ_threat
    Ultra-short half-life ideal for the abrupt offset when trigger relieved; ICU/arterial-line only; CONTRAINDICATED with recent PDE5 inhibitor; watch cyanide accumulation if prolonged
    rxcui 9895
  • prazosin
    add on
    alpha1_blocker
    1-2 mg PO at night (recurrence prophylaxis, NOT acute rescue) • PO • daily, for recurrent AD prevention
    triggers: recurrent_ad_prevention_program
    Alpha-1 blockade reduces frequency/severity of recurrent AD between episodes; titrate cautiously given low SCI baseline BP — Krassioukov 2009
    rxcui 8629
  • AVOID long-acting / slow-titration antihypertensives
    contraindication substitute
    do_not_use
    AVOID amlodipine, long-acting nifedipine GITS, slow IV nicardipine-only strategies as the acute agent • N/A • N/A
    triggers: acute_ad_episode
    BP can normalise abruptly the instant the trigger is relieved — long-acting agents cause profound overshoot hypotension on a low SCI baseline; this inverts the generic "gradual ≤25%/h" hypertensive-emergency paradigm

outpatient playbook — drug actions (3)

  1. 1. maintenance prazosin if recurrent AD
    rxcui 37798
    1-2 mg PO nightly • PO • daily
    trigger: Established recurrent-AD phenotype
    Chronic frequency/severity reduction
  2. 2. pre-procedure AD prophylaxis
    rxcui 7417
    IR nifedipine 10 mg ~30 min before cystoscopy/urodynamics/colonoscopy, or topical lidocaine for instrumentation • PO/topical • per procedure
    trigger: Planned procedure below the lesion
    Prevents procedure-triggered AD; AD guideline
  3. 3. home rescue agent maintained + protocol refreshed
    rxcui 4917
    GTN 0.4 mg SL or IR nifedipine 10 mg per personal plan • SL/PO • PRN
    trigger: Community AD episode
    Early self/caregiver management before EMS

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Sudden severe pounding headache + flushing/sweating ABOVE the lesion ± nasal congestion in a known SCI patient — classic autonomic dysreflexia until proven otherwise; 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; Spinal cord injury at or above T6 presenting with new hypertensive symptoms — anatomic substrate for AD (splanchnic outflow above lesion uncontrolled).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Autonomic dysreflexia (SCI ≥T6; remove trigger FIRST, short-acting titratable drugs second)** (cardio.hypertensive-emergency.autonomic-dysreflexia.v1).
Scope: 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

No severity triggers fired against current inputs.

Plan

Regimen axis: **Autonomic dysreflexia pharmacotherapy — trigger removal FIRST; short-acting titratable agents only while trigger is being relieved; nitrates contraindicated with recent PDE5 inhibitor (Consortium for Spinal Cord Medicine; 2025 ACC/AHA)**.
1. Upright positioning + loosen constrictors + trigger removal (PRIMARY therapy) Sit fully upright, lower legs, loosen clothing/binders/leg-bag; unblock or replace catheter; disimpact bowel with topical anaesthetic; offload pressure injury N/A immediate, before drugs (non_pharmacologic, first line) — Consortium for Spinal Cord Medicine AD guideline — positioning + trigger eradication is definitive and resolves the majority of episodes; bladder cause in ~75-85%
2. nitroglycerin GTN 0.4 mg SL spray or 2% paste 1 inch to skin (wipe off once BP controlled) SL/topical repeat/titrate q3-5 min to SCI baseline (nitrate_vasodilator, first line) — Rapid onset, easily removed (paste wiped off) for fast offset when trigger relieved — Krassioukov 2009 (PMID 19651276); ABSOLUTELY CONTRAINDICATED if PDE5 inhibitor within 24 h (sildenafil/vardenafil) or 48 h (tadalafil)
3. nifedipine (immediate-release) 10 mg capsule bite-and-swallow PO may repeat once after 20-30 min (dihydropyridine_ccb, first line) — Short-acting, no nitrate interaction with PDE5i — preferred when sildenafil/tadalafil precludes GTN; bite-and-swallow (NOT sublingual) for predictable rapid absorption per AD guideline
4. captopril 25 mg sublingual/chewed SL/PO once; reassess in 15-20 min (ace_inhibitor, second line) — Rapid-onset short-acting alternative; avoid if hyperkalaemia or significant CKD (SCI patients have high CKD prevalence — check eGFR)
5. labetalol 10-20 mg IV over 2 min, repeat/double q10 min (max ~300 mg) in a monitored setting IV titrate to SCI baseline (alpha_beta_blocker, rescue) — IV titratable for refractory/severe AD with monitoring; combined alpha-beta blockade counters the sympathetic surge — ESC/ESH 2023 hypertensive-emergency framework
6. sodium nitroprusside 0.3-0.5 mcg/kg/min IV, titrate (arterial-line monitored ICU) IV continuous, titrate to SCI baseline (arteriolar_venodilator, rescue) — Ultra-short half-life ideal for the abrupt offset when trigger relieved; ICU/arterial-line only; CONTRAINDICATED with recent PDE5 inhibitor; watch cyanide accumulation if prolonged
7. prazosin 1-2 mg PO at night (recurrence prophylaxis, NOT acute rescue) PO daily, for recurrent AD prevention (alpha1_blocker, add on) — Alpha-1 blockade reduces frequency/severity of recurrent AD between episodes; titrate cautiously given low SCI baseline BP — Krassioukov 2009
8. AVOID long-acting / slow-titration antihypertensives AVOID amlodipine, long-acting nifedipine GITS, slow IV nicardipine-only strategies as the acute agent N/A N/A (do_not_use, contraindication substitute) — BP can normalise abruptly the instant the trigger is relieved — long-acting agents cause profound overshoot hypotension on a low SCI baseline; this inverts the generic "gradual ≤25%/h" hypertensive-emergency paradigm

Setting playbook (outpatient) — Longitudinal SCI care to minimise AD recurrence: durable bladder/bowel programmes, skin surveillance, pre-procedure prophylaxis, reproductive planning for women, education refresh, periodic plan review
9. maintenance prazosin if recurrent AD 1-2 mg PO nightly PO daily — Established recurrent-AD phenotype (Chronic frequency/severity reduction)
10. pre-procedure AD prophylaxis IR nifedipine 10 mg ~30 min before cystoscopy/urodynamics/colonoscopy, or topical lidocaine for instrumentation PO/topical per procedure — Planned procedure below the lesion (Prevents procedure-triggered AD; AD guideline)
11. home rescue agent maintained + protocol refreshed GTN 0.4 mg SL or IR nifedipine 10 mg per personal plan SL/PO PRN — Community AD episode (Early self/caregiver management before EMS)

Non-pharmacologic actions:
- Durable bladder/bowel programme
- Skin surveillance + seating/pressure optimisation
- Annual AD education refresh + wallet card
- Reproductive planning with MFM for women
- Proceduralist communication of AD prophylaxis plan

AVOID / contraindication checks:
- Nitrate_absolute_contraindication_if_pde5_inhibitor_within_24h_sildenafil_vardenafil_or_48h_tadalafil
- Avoid_long_acting_antihypertensive_as_acute_agent_overshoot_hypotension_risk
- Captopril_avoid_in_significant_ckd_or_hyperkalaemia (check CKD EPI eGFR)
- Beta_blocker_monotherapy_caution_unopposed_alpha_in_pure_sympathetic_surge (prefer combined alpha beta labetalol)
- Decision:trigger_removal_is_primary_therapy_drugs_are_a_bridge
- Decision:pharmacotherapy_only_if_sbp_persistently_above_150_or_symptomatic_while_trigger_sought
- Decision:target_is_the_patient_own_sci_baseline_not_a_general_population_threshold
- Decision:stop_drug_immediately_when_trigger_relieved_to_prevent_overshoot
- Decision:pre_procedure_ad_prophylaxis_with_nifedipine_or_topical_anaesthetic_for_cystoscopy_colonoscopy_urodynamics
- Decision:labour_triggered_ad_in_sci_woman_comanage_with_mfm_distinguish_from_eclampsia

Monitoring

Regimen monitoring:
- serial bp and hr every 2 to 5 min during episode and for 2h after resolution
- continuous telemetry if iv agents or end organ injury
- neuro checks if any surge symptoms or focal signs (ICH/PRES screen)
- reassess bladder and bowel programme adequacy after each episode
- document trigger and response time for recurrence prevention plan
- bp rebound or overshoot surveillance especially if long acting agent inadvertently used

Setting (outpatient) monitoring:
- Quarterly programme review
- Episode diary
- Annual renal/bladder imaging surveillance
- Annual action-plan + caregiver-competence check

Follow-up plan: 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
- Close-out criterion: recurrence-prevention plan + patient/caregiver education + procedural prophylaxis documented

Monitoring phase: 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

Disposition

Current setting: outpatient — Longitudinal SCI care to minimise AD recurrence: durable bladder/bowel programmes, skin surveillance, pre-procedure prophylaxis, reproductive planning for women, education refresh, periodic plan review

Disposition criteria:
- Indefinite SCI longitudinal co-management; AD is a recurrent risk for life in lesions ≥T6

Escalation triggers (move to higher acuity):
- Rising episode frequency → urology/SCI re-evaluation (stones, detrusor overactivity, catheter issues)
- Pregnancy → MFM AD birth plan (epidural anaesthesia blunts AD)
- Any end-organ event → ED + reassessment

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [SEVERE] AD surge with focal neurological deficit, thunderclap headache, seizure, or encephalopathy — hypertensive intracerebral haemorrhage or posterior reversible encephalopathy syndrome (PRES); a leading cause of AD-related death
- [SEVERE] SCI patient (very high background ED-treatment prevalence) took sildenafil/vardenafil within 24 h or tadalafil within 48 h — nitrate vasodilators (GTN, nitroprusside) are absolutely contraindicated due to refractory hypotension risk
- [SEVERE] Persistent severe hypertension despite upright positioning, constrictor release, catheter management and disimpaction — atypical/occult trigger (occult fracture, acute abdomen, DVT, intra-abdominal pathology) or an alternative diagnosis (phaeochromocytoma, thyroid storm, pre-eclampsia)

Citations

- Consortium for Spinal Cord Medicine — Acute Management of Autonomic Dysreflexia (PVA CPG) + 2025 ACC/AHA Hypertension + ESC/ESH 2023 hypertensive emergencies [PMID:19651276](https://pubmed.ncbi.nlm.nih.gov/19651276/)
- Cited evidence (PMID 28506502) [PMID:28506502](https://pubmed.ncbi.nlm.nih.gov/28506502/)
- Cited evidence (PMID 24090290) [PMID:24090290](https://pubmed.ncbi.nlm.nih.gov/24090290/)
- Cited evidence (PMID 23459323) [PMID:23459323](https://pubmed.ncbi.nlm.nih.gov/23459323/)
- Cited evidence (PMID 11014502) [PMID:11014502](https://pubmed.ncbi.nlm.nih.gov/11014502/)

Last reconciled with current guidelines: 2026-05-15.
References
  • Consortium for Spinal Cord Medicine — Acute Management of Autonomic Dysreflexia (PVA CPG) + 2025 ACC/AHA Hypertension + ESC/ESH 2023 hypertensive emergencies — PMID:19651276
  • Cited evidence (PMID 28506502) — PMID:28506502
  • Cited evidence (PMID 24090290) — PMID:24090290
  • Cited evidence (PMID 23459323) — PMID:23459323
  • Cited evidence (PMID 11014502) — PMID:11014502