Nitrous Oxide Gas May be a Promising Therapy for Acute Priapism in Patients with Sickle Cell Disease: A Case Report

Background : Nitrous oxide (N₂O) is an inhalational medication that has anxiolytic, amnestic, potent venodilatory and mild-to-moderate analgesic properties commonly used in the emergency department (ED) setting. N₂O has a rapid onset of action (<5 minutes) and recovery (< 5 minutes) and can be quickly titrated to effect without the need for IV access. It has few side effects, does not require renal or hepatic metabolism for excretion and has no reports of allergic reaction. Priapism is a serious complication of sickle cell disease (SCD) affecting approximately 35% of males, with an adverse impact on quality of life. Treatment options are limited and not evidence based, including hydration, alkalization, analgesia, oxygenation to prevent further sickling, and exchange transfusion. Patients who do not respond within 4 hours often require a painful invasive procedure that includes aspiration of blood from the corpus cavernosum and phenylephrine injections. Case reports have described a therapeutic benefit from oral pseudoephedrine, sildenafil, and IV arginine, however controlled clinical trials are lacking. Although a 50:50 nitrous oxide/oxygen mix is commonly used in France to enhance analgesia in patients with SCD and vaso-occlusive pain events (VOE) not sufficiently responding to IV morphine, there are no reports of its use to treat priapism.

Objective: To describe the effects of N₂O for the treatment of acute priapism associated with SCD in a pediatric ED.

Methods: This is a case report of a child with Hb-SS who on 2 separate occasions presented to the ED with acute priapism that failed oral therapy (pseudoephedrine and opioids). On each occasion he received standard treatment for VOE pain based on institutional guidelines for SCD that included oral opioids and intranasal fentanyl prior to IV access. N₂O gas was utilized to help facilitate IV catheter placement.

Results: In each presentation (at ages 8 and 10 years) the patient experienced complete resolution of the priapism within 5-15 min of receiving N₂O (max 60%). The patient was discharged from the ED following each presentation and had no recurrence during the subsequent week.

Conclusions: Priapism is a challenging complication of SCD associated with long-term morbidity and a paucity of treatment options. Given the risks and inconsistent results of current recommended therapy, N₂O may represent a potentially superior treatment option for priapism presenting to the ED that warrants further investigation. Although anecdotal, N₂O inhalation is a safe consideration during a time when a treating ED physician has few alternatives.