High-Dose Nitroglycerin for Sympathetic Crashing Acute Pulmonary Edema (SCAPE)
Pharmacy Friday Pearl – Pharmacy & Acute Care University
Introduction
- SCAPE is a form of hypertensive heart failure triggered by a surge in catecholamines.
- The result is pulmonary capillary leakage and alveolar flooding.
- Management includes non-invasive ventilation and pharmacologic agents such as nitroglycerin.
- Dose-dependent afterload reduction with nitroglycerin requires doses >50–150 mcg/min.
Pharmacology of Nitroglycerin (NTG)
| Parameter | Details |
|---|---|
| Mechanism of Action | Organic nitrate vasodilator that reduces tension on vascular smooth muscle and dilates peripheral veins and arteries (at higher doses). |
| Dose |
• Chest pain: 5–400 mcg/min (starting at 5 mcg/min) • Pulmonary edema/afterload reduction: 50–400 mcg/min • Titrate to symptom improvement and tolerated blood pressure |
| Administration |
• IV infusion: 50–400 mcg/min until symptom resolution • IV bolus: 400–2000 mcg over 2–5 min (check hospital policy) • Sublingual: 400 mcg tab, 2–4 tablets (≈160–320 mcg/min IV) • Ointment: slow onset 30–60 min |
| PK/PD |
• Onset: IV 1–5 min; SL 1–3 min • Peak: 3–15 min • Duration: IV 5–10 min; SL 10–60 min • Elimination: 22% renal |
| Adverse Effects | Headache, hypotension, syncope, rebound hypertension, tolerance with prolonged use (~24 hrs) |
| Warnings/Interactions |
• PDE inhibitors • Aortic stenosis, preload-dependent cardiomyopathy, hypertrophic obstructive cardiomyopathy, hypotension at any time |
| Compatibility | Incompatible with levofloxacin, SMX-TMP, daptomycin, and phenytoin |
Clinical pearl: Higher doses of IV or bolus nitroglycerin may reduce ICU admissions and intubation risk in SCAPE.
Overview of Key Evidence
| Author/Year | Design (n) | Intervention & Comparison | Key Findings |
|---|---|---|---|
| Patrick, 2020 | Observational (n=48) | IV NTG 1 mg bolus by EMS | ↓SBP by 31 mmHg, ↓HR by 10 bpm, ↑O2 from 86% to 98%; 2% symptomatic hypotension |
| Hsieh, 2018 | Case Report (n=3) | SL NTG 0.6 mg x 3, IV NTG bolus 1 mg Q2 min, then infusion 40 mcg/min | Normalized respiratory status, avoided intubation & ICU admission |
| Paone, 2018 | Case Report (n=1) | IV NTG 400 mcg/min titrated | Symptom resolution at 6 minutes |
| Wilson, 2016 | Observational (n=395) | IV NTG bolus (500–2000 mcg) Q3–5 min vs infusion vs both | ↓ICU admissions, shorter LOS, no increase in intubations |
| Levy, 2007 | Observational (n=29) | IV NTG bolus 2 mg IV Q3 min | ↓Intubation, ↓BiPAP/ICU admission |
| Sharon, 2000 | RCT (n=40) | IV isosorbide bolus 4 mg Q4 min vs infusion + BiPAP | ↓Intubation, MI, mortality; ↑PaO₂ |
| Cotter, 1998 | RCT (n=104) | IV isosorbide bolus 3 mg Q5 min + furosemide vs infusion titration | ↓MV & MI, ↑PaO₂, fewer adverse effects |
Clinical Conclusions
- High-dose nitroglycerin (bolus and/or infusion) is effective in rapidly reducing preload and afterload in SCAPE.
- Doses of ≥400 mcg/min (or equivalent bolus) are supported by case reports and observational studies.
- High-dose IV or sublingual NTG has been associated with improved respiratory status, fewer ICU admissions, and reduced need for intubation.
- Symptomatic hypotension is rare but monitoring is necessary, especially with bolus regimens.
- Bolus dosing strategies may outperform continuous infusions in acute SCAPE decompensation.
Full Reference List
- Nitroglycerin. Micromedex [Electronic version]. Greenwood Village, CO: Truven Health Analytics. Retrieved March 5, 2020, from http://www.micromedexsolutions.com/
- Kramer K. Am Heart J. 2000;140:451–5.
- Agrawal N. Crit Care Med. 2016;20:39–43.
- Mebazaa A. Eur J Heart Fail. 2015;17:544–58.
- Viau DM. Heart. 2015;101:1861–7.
- McMurray JJ. Eur J Heart Fail. 2012;14:803–69.
- López-Rivera F. Am J Case Rep. 2019 Jan 21;20:83–90.
- Clemency BM. Prehosp Disaster Med. 2013 Oct;28(5):477–81.
- Yancy CW. J Am Coll Cardiol. 2013;62:e147–239.
- Hsieh Y. Turk J Emerg Med. 2018;18(1):34–36.
- Wilson SS. Am J Emerg Med. 2017;35(1):126–31.
- Levy P. Ann Emerg Med. 2007;50:144–52.
- Sharon A. J Am Coll Cardiol. 2000;36(3):832–7.
- Cotter G. Lancet. 1998;351(9100):389–93.
- Paone S. Am J Emerg Med. 2018;36(8):1526.e5–1526.e7.
- Patrick C. Prehosp Emerg Care. 2020 Jan 27:1–7.