Some complications have been discussed already under the heading “Is an epidural safe?”
Blood pressure drop
Because the local anaesthetic also blocks the nerves that supply blood vessels, these vessels will relax and dilate, resulting in a drop in blood pressure. The drop is mostly mild, but can be more pronounced if the patient is dehydrated or taking medication against high blood pressure. Before performing an epidural, the anaesthetist will therefore make sure that you’re given extra fluids intravenously. It is also advisable not to take some high-blood pressure medications while the epidural infusion is running.
Itchiness and nausea
Sometimes the anaesthetist adds morphine or related drugs to the epidural mixture that is infused after the operation. A cumbersome side effect, especially of the morphine, is nausea and itchiness, but fortunately it’s easy to treat.
Sedation and respiratory depression
Again morphine and related drugs are responsible for this, especially morphine. They can make you feel a bit drowsy and sleepy and decrease your impulse to breathe. Fortunately this rarely happens, but the nursing staff would have to check every two to four hours that you’re not becoming too sleepy and that your breathing is fine.
Headache is another complication which is rare and not dangerous, but uncomfortable. The incidence is about seven in 1 000 epidurals. It happens when the epidural needle accidentally punctures the dural membrane, causing spinal fluid to leak. This spinal fluid is in direct connection with the fluid around the brain, and any disturbance in the volume of this fluid adds stress to the sensitive ligaments around the brain, resulting in a headache. It is mostly self-limiting, but sometimes takes weeks to resolve.
The intensity of the headache ranges from mild and easily treatable to severe, where the patient has to lie down flat for a few days, sometimes up to a week or more. In severe cases, the only helpful treatment is to seal the opening in the dural membrane through which the spinal fluids are leaking. This is done with a so-called blood patch, where a small amount of the patient’s own blood is injected into the epidural space. The procedure will give immediate relief in 70% of cases.
A less invasive treatment is acupuncture. It involves the insertion of two small acupuncture needles into the top part of the neck muscles, and often provides effective relief. The treatment can be repeated safely and easily if necessary.
Reviewed by Prof CL Odendal, senior specialist at the department of anaesthesiology at the University of the Free State, April 2010.