What is the next step in managing refractory priapism with hypoxemia, hypercapnia, and acidosis?

Management of Refractory Priapism with Hypoxemia, Hypercapnia, and Acidosis

For a 52-year-old man with an 18-hour history of priapism refractory to aspiration and blood gas values showing hypoxemia (pO₂ 30 mmHg), hypercapnia (pCO₂ 60 mmHg), and acidosis (pH 7.25), the next step in management should be cavernosal injection of phenylephrine (option C).

Rationale for Phenylephrine Injection

The American Urological Association (AUA) guidelines recommend a stepwise approach to managing ischemic priapism:

1. The blood gas values confirm ischemic priapism with characteristic hypoxemia, hypercapnia, and acidosis 1.
2. Despite previous aspiration, the priapism persists, indicating the need for additional intervention.
3. Before proceeding to surgical shunting procedures, intracavernosal injection of sympathomimetics (specifically phenylephrine) should be attempted 2, 1.
4. The AUA explicitly states that "the use of surgical shunts for the treatment of ischemic priapism should be considered only after a trial of intracavernous injection of sympathomimetics has failed" 2.

Phenylephrine Administration Protocol

• Use phenylephrine at a concentration of 100-500 μg/mL diluted in saline 1, 3
• Inject 1 mL every 3-5 minutes for up to one hour (maximum 1 mg in an hour) 3
• Monitor for cardiovascular side effects including hypertension, reflex bradycardia, tachycardia, and cardiac arrhythmias 2, 1

Why Not Other Options?

• Penile duplex Doppler ultrasound (option A): This is primarily diagnostic for non-ischemic priapism and is unnecessary when blood gas confirmation of ischemic priapism is already available 1.

• Arteriography with selective embolization (option B): This is the treatment of choice for non-ischemic (high-flow) priapism, not ischemic priapism 1, 4.

• Distal glanular shunt (option D) or proximal corpora-spongiosal shunt (option E): Surgical shunting procedures should only be considered after failure of intracavernosal phenylephrine injection 2, 1. If shunting becomes necessary, distal shunts should be attempted before proximal shunts.

Important Considerations

• The 18-hour duration is concerning but not yet at the point where phenylephrine would be completely ineffective. The AUA guidelines note that phenylephrine becomes "less effective in priapism of more than 48 hours in duration" 2.

• However, patients should be informed that priapism lasting more than 18 hours carries a significant risk of erectile dysfunction 1.

• If phenylephrine injection fails, proceed to surgical shunting, with distal shunts (cavernoglanular/corporoglanular) as the first choice due to easier performance and fewer complications 2, 1.

• Research shows that in cases of very prolonged ischemic priapism (>48-72 hours), high-dose phenylephrine may be ineffective due to widespread smooth muscle cell apoptosis 5, but at 18 hours, sympathomimetic injection still has potential efficacy.

Treatment Algorithm

1. Confirm ischemic priapism with blood gas analysis (already done)
2. Attempt aspiration with or without irrigation (already attempted)
3. Current step: Intracavernosal phenylephrine injection
4. If unsuccessful, proceed to distal shunting procedures (Winter, Ebbehøj, or Al-Ghorab)
5. If distal shunts fail, consider proximal shunting procedures (Quackels or Grayhack)