Postoperative pain

From greek.doctor

Surgery is painful and causes pain after the anaesthesia has weaned off. Management of postoperative pain is a major part of anaesthesiology and surgery. Post-operative pain not only is annoying to the patient, but it increases the risk of chronic post-surgical pain, acute myocardial infarction, arrhythmias, and poor outcomes in general. Post-operative pain occurs from the surgery itself, from the immobility and positioning during surgery, and from direct or indirect trauma to nerves.

Pain is not only the noxious stimulus, but also includes emotional, psychological, and social components. Fear or anxiety, for example, worsens pain.

Central sensitization to pain occurs during surgery and can worsen the postoperative pain or cause chronic pain. Preventing central sensitization is important in reducing pain.

Evaluation

It’s important to evaluate the patient’s postoperative pain, as all patients are different and experience pain differently. This can be done with a variety of different scales, like the numerical rating scale (NRS) for adults and the visual analogue scale (VAS) for children.

Management

The WHO has a pain management ladder, which can be used in postoperative pain. The first step includes non-opioid analgesics, the second weak opioids, and the third and final step strong opioids. Adjuvants can be added at any step. However, it’s important to note that in very strong pain we can start at step 3, there’s no reason to try the other steps first.

Nowadays we prefer preventive analgesia, which is a multimodal approach which aims to prevent central sensitization by blocking all pain signals associated with the surgery, from the time of the incision to the final wound healing.

Regional anaesthesia is widely used to prevent postoperative pain. A catheter can be placed so that local anaesthetics can be applied for days or weeks. Nerve blocks with local anaesthetics can be placed at the end of the surgery to provide post-operative analgesia.

Nonopioids, including NSAIDs, COX-2 inhibitors, and paracetamol, are essential in reducing the need for opioids in postoperative pain.

Opioids have a variety of problems, but their use is often unavoidable with regards to postoperative pain. There are a variety of opioids available:

  • Weak opioids
    • Tramadol
    • Dihydrocodeine
    • Codeine
  • Strong opioids
    • Morphine
    • Oxycodone
    • Fentanyl (oral, IV, or transdermal patch)

Many adjuvant analgesics are effective in preventing and treating postoperative pain, like gabapentin, pregabalin, amitriptyline, etc. Gabapentin and pregabalin are especially useful for neuropathic pain.

Patient-controlled analgesia (PCA) refers to an infusion pump where the patient themselves can choose when analgesic is released. This allows the patient to spend less time in pain, and patients tend to use less analgesics than if following a set schedule. It is commonly used for postoperative and cancer pain.

Non-pharmacological modalities are also important, like psychotherapy, transcutaneous electrical nerve stimulation (TENS), physiotherapy, acupuncture, yoga, etc.