When indicated, epidural analgesia is the Rolls-Royce of postoperative pain relief. It can be administered for all types of surgery of the chest, abdomen and legs, but not the neck, arms or head. The latter would involve an epidural effect that reaches too high up, making it impossible to breathe or maintain a normal blood pressure and heart rate. Since the local anaesthetic in the epidural space blocks the nerves where they enter (and leave) the spinal cord, all pain and sensation can be taken away, even while you move or cough.
It differs from morphine and other painkillers that are administered systemically (i.e. orally, intravenously, intramuscularly or rectally – they go to the “whole system”) in that systemically administered painkillers can never completely relieve pain. Pain receptors in the brain and tissues are blocked, but not the action of the nerves that conduct the pain impulse to the spinal cord and brain. With systemic painkillers, you are rarely pain free in the physiotherapy, movement and coughing can still be painful.
Because the pain relief is so complete, breathing and coughing are completely or almost completely free of pain. This allows for better expansion of the lungs, better uptake of oxygen, and better coughing up of secretions, which is especially important for smokers. Overall, it leads to a decreased risk of pneumonia.
Less stress on the heart
Pain increases heart rate and blood pressure, which can be harmful to patients with a poor heart and even cause a heart attack. Perfect pain relief with an epidural can therefore decrease the risk of cardiac complications after an operation.
The local anaesthetic in the epidural infusion improves bowel contraction. Systemically administered morphine (via intravenous or intramuscular injection) paralyses the bowel, and this can be avoided almost completely if epidural pain relief is used. It allows patients to start eating the day after surgery, even after abdominal operations (i.e. surgery on the intestines).
Decreased risk of deep venous thrombosis (DVT)
Major surgery, and especially orthopaedic surgery, predisposes one to the formation of blood clots in the legs or pelvis, which can shoot up to the lungs and be fatal. Epidural analgesia decreases the risk for this complication by 30 percent.
Decrease in general stress response
Surgery subjects your body to a lot of stress – not the stress of daily life, such as sitting in traffic jams or living at a hectic pace, but physiological stress: pain, cooling during surgery, blood loss, etc. If all these stressing factors are treated appropriately, the challenge (“stress”) to the body will be much less, allowing for a speedier and less complicated recovery. For example: the stress of pain increases your heart rate and blood pressure, and in a person with heart disease, this can lead to a heart attack.
Decreased incidence in chronic pain
Poorly treated pain after surgery can sometimes become chronic and last several months or years. This has been described for chest surgery, but might also be true of other types of surgery.
Reviewed by Prof CL Odendal, senior specialist at the department of anaesthesiology at the University of the Free State, April 2010.