A 72-year-old female renders EMS after experiencing acute onset of dyspnea while at rest. When the EMS crew arrives on the scene, they find the patient in acute respiratory distress. She is sitting at the edge of a chair in the kitchen in a tripod position and can only speak 1-2 words at a time. She is pale and diaphoretic, her breathing is rapid and labored. Audible crackles are present without auscultation. It is clear that this patient is critically ill. Initial assessment reveals a blood pressure of 230/160 mmHg, a heart rate of 130 beats per minute, a sinus tachycardia on the monitor, a respiratory effort of 60 breaths per minute, a room air SpO2 of 78%, and an ETCO2 of 18 mmHg. Upon auscultation, rales were noted in all lung fields. One member of the crew immediately administered 3, 0.4mg SL sprays of nitroglycerine while the other member prepared to place the patient on a continuous positive airway pressure (CPAP) mask. The patient tolerated the CPAP well and a modicum of relief was immediately noted after the nitroglycerine was administered and the mask was secured. IV access was established, and A 12-lead EKG was obtained which showed no signs of ischemia or infarct. Reassessment of the patient’s vital signs revealed a blood pressure of 200/120mmHg, a heart rate of 124 bpm, a respiratory effort of 60 breaths per minute, an SPO2 of 88%, and an ETCO2 of 20 mmHg. The patient’s condition had improved somewhat but her work of breathing continued to be labored and unsustainable. One crew member expressed concerns regarding removing the CPAP mask in order to administer additional doses of sublingual nitroglycerin (NTG). Is there another alternative?
EMS administration of nitroglycerin for SCAPE
The most effective treatment modality for this patient in the prehospital environment would be additional doses of NTG. NTG is a potent vasoactive medication that at high doses causes both systemic arterial and venous vasodilation. This results in improved cardiac contractility and symptomatic improvement by decreasing both preload and afterload. In the past, EMS clinicians’ only options were continued use of sublingual sprays/tablets or the application of topical NTG paste. CPAP, which has become ubiquitous in prehospital care, is known to substantially reduce intubation and ICU admission for patients that receive it and is a vital part of the treatment strategy for patients experiencing severe respiratory distress. (23566337)
However, it is challenging to provide ongoing SL NTG therapy to a patient on CPAP. To give SL NTG, the mask must be unsecured and at least partially removed. Many EMS practitioners are hesitant to do this because it can be challenging to reapply, and the patient may no longer tolerate it. The efficacy and consistency of topical NTG is widely debated. There were no other options until recently.
However, two recent studies concluded that IV NTG administered in the field by trained paramedics was effective, safe, and potentially reduced patient mortality. (31900011) (34543690)
In its 2019 iteration, the Pennsylvania statewide EMS protocols were updated to reflect the conclusions of the research. When patients remain hypertensive (systolic >160mmHg) after initial intervention with SL NTG, the protocol allows for NTG infusions of 5-200mcg/minute titrated to a systolic blood pressure greater than 100mmHg or there is a 25% drop in blood pressure, as long an electronic IV pump is available. Many EMS agencies throughout the commonwealth and across the country do not have access to electronic IV pumps so a bolus option is also available. If bolus nitroglycerine is going to be utilized, then 200mcg can be administered via slow IV push Q5 minutes as long as the patient’s systolic blood pressure remains greater than 100mmHg or it drops more than 25%. (PA protocol)
Take note, IV NTG for SCAPE is not intended to be used in leu of rapid administration of SL NTG or the application of CPAP. It should be used to supplement these vital interventions after consulting with online medical direction.
While one member of the crew consulted with medical command via radio the other member prepared a NTG bolus. The medication was prepared by drawing 0.5mL of solution out of a vial of NTG that contained 100mg/250mL (400mcg/mL). The medication was then diluted with 2.5mL of normal saline solution which provided 200mcg of NTG in 3mL of solution. After the plan was approved by medical command the medication was slowly administered over 2-minutes. The patient continued to improve. Reassessment of the patient’s vitals signs revealed a blood pressure of 170/100mmHg, a heart rate of 118 bpm, respirations 40 and less labored, SPO2 of 94%, and an ETCO2 of 23 mmHg. The patient was secured on a stretcher, moved to the ambulance, and transport to the ED was initiated. While enroute to the ED, 1 additional 200mcg dose of IV NTG was administered and the patient continued to improve. Upon arrival at the hospital the patient’s condition had improved so much that she was quickly transitioned from CPAP to low flow oxygen via nasal cannula.
- -The combination of CPAP and NTG are an incredibly impactful treatment strategy for patients experiencing SCAPE in the field.
- -Administering SL NTG when a patient has already been placed on CPAP can be challenging and may be problematic.
- -IV NTG via pumped infusion or slow IV bolus has been demonstrated to be safe and effective for use by trained paramedics when it is impractical to give it via the SL route.