PlateletTransfusion AABBandICTMGInternationalClinical PracticeGuidelines 2025

Prevention of CLABSI

SCAPE

Sympathetic crashing acute pulmonary edema ( SCAPE) is a specific  subset of acute heart failure in which patients present with acute onset of pulmonary congestion and severe dyspnea with severe systolic hypertension due to sympathetic surge.

Pathophysiology

• Catecholamine release during this sympathetic surge leads to an increase in arterial tone and redistribution of fluid causing flash pulmonary edema.Activtion of renin-angiotesin-aldosterone system leads to increase in peripheral vascular resistance, sodium and water resabsorption, which worsens the cardiac function.Hypoxia, dyspnea and further sympathetic surge ensue as the intravascular fluid shifts into the pulmonary interstitium and alveoli.

• The shift of fluid in the lung is the major problem rather than hypervolemia.

Treatment

• NTG

• NTG is converted to nitirc oxide while activating cyclic guanosine monophosphate. This leads to smooth muscle relaxation and thereby reducing the preload due to venodilatation and higher doses reduces afterload by causing arterial dilatation.
• But conventional low dose NTG < 100mcg/min has not been shown to reduce the arterial tone. Studies have shown much higher doses > 100mcg/min  (upto 250 mcg/min) have shown beneficial in reduction in arterial tones.

• Diuretics
• Loop diuretics such as furosemide have been primarily used in the management of acute pulmonary edema. The effect starts in 30 min and peaks by 1.5h. 
• The role of diuretics in SCAPE is doubtful in euvolemic patients as the mechanism is fluid redistribution rather than fluid overload. 

• NIV

• NIV improves oxygenation, opens collpased alveoli. NIV causes reduction of preload and afterload. NIV also reduces the work of breathing.
• NIV should be started with higher PEEP (12-14) and titrated once the patient is stabilised. 

Evidence

• Kelly at al (Am J Emerg Med. 2023) published a retrospective, single centre study done on 41 patients to compare the clinical outcome when using low dose  NTG < 100 mcg/min (n=27)v/s high dose NTG > 100mcg/min (n=14). 8 out of 14 patients in the high dose group reached their BP target within first hour of treatment compared to 6 out of 27 in the low dose group. 

• Houseman et al (Am J Emerg Med. 2023) published a study on 67 patients to assess the clinical outcome on patients receive high dose NTG > (100 mcg/min).Study used median dose of 100 mcg/min with maximum upto 400mcg/min. Study concluded that high dose NTG infusion is safe.

• Levy at (Ann Emerg Med. 2007) published a feasibility and outcome assessment of the treatment of severe decomopensated heart failure with high dose nitroglycerin. Enrolled patients (N=29) were given bolus high dose of NTG (2mg) every 3 minutes upto a total of 10 doses. Patients treated with high dose NTG was assosciated with ET, BiPAP and ICU admisssion less frequently. 

Conclusion

• SCAPE is a important medical emergency and it is important recognise this entity . High dose NTG and NIV are two main treatment modality.

Reference

• Verma A, Jaiswal S, Mahawar A, Lal M, Gupta S, Begum R. Managing Patients With Sympathetic Crashing Acute Pulmonary Edema (SCAPE) Using the SCAPE Treatment Protocol: A Case Series. Perm J. 2024 Jun 14;28(2):116-120. doi: 10.7812/TPP/23.149. Epub 2024 Mar 29. PMID: 38549439; PMCID: PMC11249274.

• Agrawal N, Kumar A, Aggarwal P, Jamshed N. Sympathetic crashing acute pulmonary edema. Indian J Crit Care Med. 2016 Dec;20(12):719-723. doi: 10.4103/0972-5229.195710. PMID: 28149030; PMCID: PMC5225773.