gms | German Medical Science

Objectives: To examine the use of opioid analgesics in neurosurgical patients, using British National Formulary (BNF) recommendations for opioid dosing as a guide. To correlate opioid use with pain scores using a simplified visual pain score.

Methods: Patients who had undergone neurosurgery in the previous two days were identified on ward round each day. Patients were excluded if they were unable to rate their pain on a simple visual pain scale, if their drug chart was unavailable, or they did not consent to participation. Patients were asked to rate their pain on a smiley face chart and prescriptions for regular and “as required’ analgesics were recorded.

Results: One-hundred patients were identified over six weeks, of which 51 were male and the average age was 55.9 years. Operations included craniotomy (n=30), burrhole(s) alone (n=22), spinal surgery (n=19), endovascular procedures (n=11), craniectomy (n=8), transsphenoidal surgery (n=4), cranial nerve decompression (n=4) and cranioplasty (n=2).

Ninety-three percent of patients had regular paracetamol prescribed and the remaining 7 patients had it on the “as required” section of the drug chart. Thirty-eight patients had regular non-paracetamol analgesia prescribed, which included codeine/dihydrocodeine (n=16), long acting strong opioids (n=8), neuropathic pain medications (n=3), nefopam (n=2), and non-steroidal anti-inflammatories (n=1) and a combination of two or three analgesics (n=8). Ninety-four percent had “as required” opioids, most commonly immediate release oral morphine (n=68), followed by a combination of oral morphine and codeine (n=11), then codeine alone (n=9), oxycodone (n=4) and patient controlled analgesia (n=2).

The BNF suggests that the “as required” dose of opioid should be 1/6^th – 1/10^th the dose of the total regular opioid used in 24 hours. Just three patients had the suggested “as required” dose available; one of whom reported no pain, one some pain, and one severe pain. Of those patients with regular long acting opioids prescribed, the majority (n=24) had too large a dose of “as required” opioid prescribed (or indeed, too low a dose of regular opioid). Of those patients who had <10% of their total regular opioid available “as required”, three had no breakthrough pain relief at all and one had 3 to 6% (although this patient was already taking three opioids regularly for difficult to manage pain). Half of the patients reported some pain post-operatively, with 10% selecting the worst pain score, regardless of whether or not regular opioids were prescribed.

Conclusion: Very few of the analgesia prescriptions followed the BNF guidance, hence it remains unclear whether regular opioids are helpful in post-operative neurosurgical patients. Further work is being undertaken to increase the use of long acting opioids and assess the effect on pain score in these patients, in the hope of developing prescribing guidelines.