Dr Francois Stapelberg,1 Dr Jian Li,1 Irene Zhang1, Christin Coomarasamy1,
1NZ National Burn Centre and Middlemore Hospital, Auckland, New Zealand
Gabapentininoids are registered for use in epilepsy and neuropathic pain, but are commonly used off-label during acute pain for opioid sparing. In burn injured patients there are some evidence that show reduced components of neuropathic pain in burn injured patient, but no significant opioid sparing.
In our burn centre we changed our practice to starting gabapentin on admission to the ICU along with early enteral feeding. This followed our experience with a patient who developed severe opioid induced hyperalgesia. This afforded us the opportunity to study the potential for opioid sparing from gabapentin as a single change to practice.
The study involved recording daily opioid consumption in burn patients admitted to ICU and started on enteral gabapentin, with propensity matched controls before the introduction of gabapentin. The study was powered to determine a clinically significant opioid sparing of 30% which we determined to be the minimum sparing that would result in benefit to the patient in terms of opioid related side-effects. All analgesic medication used was converted to a total opioid equivalency score expressed as mg/day morphine.
30 sequential patients who had gabapentin administered following the change in our practice were included in the study, and matched with another 30 patients who had been treated prior to the change in practice.
Mean age was 32 (13-76), mean TBSA was 38% (15-80%) in 41 males patients out of 60. Mechanism was flame in 55 from 60 patients.
Four different statistical models were used to analyse differences in opioid use. In three models the effect size for dose reduction in opioid use was 23%, which was less than the pre-set 30% difference that was judged to be potentially clinically significant. There were non-statistically significant trend towards reduced opioid dose in two of the models used.
The use of gabapentin during the ICU period of severe burns is not supported by the findings of this trial if opioid dose reduction is used as the endpoint.
Dr Stapelberg is an anaesthetist with a long-standing involvement in burn care, with an interest in pain management and the link to long-term outcomes.