Discussion:
Acute pulmonary edema is a life-threatening condition requiring immediate treatment. Usual treatment such as intravenous diuretic therapy will take time to reduce congestion. Morphine administration can be helpful but by suppressing respiratory drive it can worsen respiratory failure and hypoxia. It is also not very effective in severe pulmonary edema needing intubation. Any agent that can rapidly and safely reduce pre and afterload is ideal for this situation. Nitroglycerin is an ideal drug in this setting. However, sublingual nitroglycerin will take a while to resolve. High-dose IV nitroglycerin has been effective in patients with acute pulmonary edema (1-3) including in pre-hospital settings (4) but is not rapidly available at the bedside. Furthermore, pharmacists and nursing staff are resistant to supply providers with high doses of IV nitroglycerin as they are not familiar with such dosing which is usually over 2-3 mg.  Nitro ointment commonly called nitro paste is widely available with excellent rapid resorption if it is administrated buccally. Buccal administration of nitro ointment has been shown to be superior compared to other nitroglycerin agents in patients with angina (5-8) In patients with chronic congestive heart failure buccal administration of nitroglycerin ointment has shown superior response in comparison to other forms of nitroglycerines for rapid onset,  longer duration of drug effect and hemodynamic response using its effect on wedge pressure. (9-16  ). Nitroglycerin ointment contains 15 mg of nitroglycerin per one inch of paste that can rapidly absorbed by buccal application simulating intravenous nitroglycerin administration. Starting with a quarter of an inch of buccal nitroglycerin ointment, about 3-4 grams of nitroglycerin can be given rapidly with each administration which can lead to rapid pre- and afterload reduction thus dramatically reducing pulmonary congestion. An important part of this treatment is the presence of adequate blood pressure. This is the reason that this type of treatment should not be initiated in patients with cardiogenic shock and BP has to be rechecked before each buccal administration.
In the setting of acute pulmonary edema without cardiogenic shock, there are limited case reports and case series that have demonstrated the effectiveness of buccal nitroglycerin application.   (17-19).  However, this very effective treatment of patients with acute pulmonary edema without cardiogenic shock is hardly utilized as the medical community is not aware of this lifesaving treatment. Every time I have used this method, every single medical staff including nurses, residents, fellows, and cardiology attendings were unaware of this treatment and were surprised about its usage and effectiveness.  This case series is the largest reported case series in this regard showing very effective and safe use of buccal nitroglycerin ointment. Due to ease of use, safety, and efficacy, the use of buccal nitroglycerin ointment should be the standard of care in patients presenting with severe pulmonary edema without cardiogenic shock in order to avoid imminent intubation and mechanical ventilation.