Background In the paediatric surgery unit, low doses of opioid analgesics are used daily for anaesthesia. Because dilutions in series are required, potential preparation errors may occur. Thus stock solution (SS) syringes are prepared each morning in the post anaesthesia care units, resulting from a 10-fold dilution of commercial products. SS syringes are then extemporaneously diluted all day long by a factor of 2, 2.5, 5 or 10 to obtain serial dilution (SD) syringes used in the operating ward.

Purpose We quantified the concentration of ketamine (Ket), remifentanil (Rem) and sufentanil (Suf) in prepared syringes to evaluate the compounding accuracy of the anaesthetic staff before injection to children.

Material and methods Over a 1 month period, Ket, Rem and Suf samples were collected from SS and SD syringes prepared in the care unit. Samples were quantified by a HPLC-UV-DAD method, previously validated according to the SFSTP-Pharma requirements. Results were expressed as bias (%) and were considered acceptable if included between acceptance limits of ±10% of the theoretical concentration (drugs with a narrow therapeutic margin).

Results 150 syringes were collected on 31 days: 73 SS (25 Suf; 24 Rem; 24 Ket) and 77 SD (36 Suf; 24; Rem; 17 Ket). Biases were not within acceptance limits for 15 of the 31 days, representing 25 syringes (17%). Focusing on dilution modalities, the total error rate and extremes biases (min; max) obtained for the 17 SD syringes out of 77 were 28% (−17%; +12%), 21% (−10%; +15%) and 14% (−7%; +14%) for Suf, Rem and Ket, respectively. For the SS syringes, the total error rate and extremes biases (min; max) obtained were 20% (−25%; +22%), 4% (−23%; +2%) and 8% (−23%; +3%) for Suf, Rem and Ket, respectively, representing 8 syringes (11%). Whatever the drug, the error rate was higher with the SD syringes compared with the SS syringes.

Conclusion We found that 22% of syringes administered to children were not within acceptance limits. In order to reduce the occurrence of compounding error in the ward, a preparation procedure will be defined. Its impact will be further assessed.

No conflict of interest