Extra Topic 5.6 -- Retrobulbar Block

Question 1

Why do you think this patient is unconscious and apneic?

Answer 1

The timing suggests that local anesthetic injected for the retrobulbar block has spread through the optic nerve sheath and into the central nervous system, resulting in general anesthesia and apnea.

However, I would also consider other possibilities, including –

• narcotic or anxiolytic overdose,
• stroke, and
• cardiac arrest.

Therefore, I would quickly assess the patient; provide supportive care, including intubation and positive pressure ventilation; review all the medications that were given; and order tests and lab work as indicated.

Question 2

What are the possible complications of retrobulbar block?

Answer 2

Complications from retrobulbar block are uncommon, but include –

• direct trauma to the optic nerve,
• retrobulbar hemorrhage,
• increased intraocular pressure (IOP) secondary to transient globe compression,
• globe perforation,
• stimulation of the oculocardiac reflex,
• intravascular or intraneural injection, and
• apnea secondary to local anesthetic spread into the CNS.

Question 3

How would you manage this patient?

Answer 3

As I mentioned before, I would cancel the case;

provide supportive care, including intubation and positive pressure ventilation;

review all the medications that were given;

order tests and lab work as indicated; and

monitor the patient closely until he returned to his baseline status.

At the same time, I would be prepared to treat any bradycardia, cardiac arrest, or seizure activity, as necessary.