The effect of opioids on field block for hernia repair: a study comparing pethidine with a placebo

Intramuscular (IM) pethidine injection is used as pre-analgesia (pre-medication) in hernia repair under local anaesthesia in some district hospitals. We evaluated the relevance of this practice in a facility based study at one of the district hospitals in Ghana.

One hundred and twenty patients above 10 years of age with a mean age of approximately 49 years diagnosed as having inguinal hernias of different sizes were recruited into the study. Each group of 60 patients was randomly selected. A maximum of 50 ml 1% lignocaine plus 2 ml (100 mg) of pethidine was used in group A and 50 ml 1% lignocaine plus 2 ml of sterile water in group B. A score ranging from 0 to 3 was assigned at the end of each surgery depending on the degree of pain experienced.

33.3%, 33.3%, 21.7% and 11.7% of patients in group A scored 0, 1, 2, and 3 respectively in pain perception while 26.7%, 33.3%, 25% and 15.0% were the scores in group B. None of the patients in group B experienced an adverse effect to any of the agents used. 2% and 5% in group A experienced nausea and generalized pruritus respectively. Post-operation condition was satisfactory and all patients were discharged the same day.