[Perioperative use of metamizole and other nonopioid analgesics in children : Results of a survey].

BACKGROUND: Nonopioid analgesics are frequently used for perioperative pain management in children. In many countries, the nonopioid metamizole (dipyrone) is administered as an alternative to paracetamol and traditional NSAIDs (nonsteroidal anti-inflammatory drugs), such as ibuprofen and diclofenac; however, concerns over possible life-threatening adverse events (agranulocytosis) have prompted a debate over the use of metamizole.

OBJECTIVE: To investigate current practice and use of nonopioid analgesics, particularly of metamizole in children younger than 14 years, in the perioperative setting. Furthermore, metamizole-related side effects, safety and approaches used to inform patients were addressed.

METHODS: A link to an online questionnaire on the perioperative use of nonopioid analgesics in children, with a specific focus on dipyrone, was sent by e‑mail to members of the German Society of Anesthesiology and Intensive Care Medicine (DGAI) and to members of the German Pain Society.

RESULTS: A total of 2284 anesthesiologists filled out the questionnaire. Of these, 1476 were involved in the perioperative care of children younger than 14 years. The majority of respondents worked in German hospitals (90.5%) but Austria, Switzerland and the Netherlands were also among the countries represented. Of the respondents, 99.1% reported using nonopioid analgesics in the perioperative setting. The NSAID, metamizole, paracetamol and COX-2 inhibitors were administered by 83.9%, 68.6%, 67.5% and 2% of the respondents, respectively. Intravenous metamizole was the preferred nonopioid analgesic during surgical procedures, but following surgery, NSAID, metamizole and paracetamol were given with the same frequency by anesthesiologists. Of the respondents, 49.3% reported using metamizole in combination with another nonopioid analgesic in cases of severe pain, 14.8% used it as the sole nonopioid analgesic, and 23.2% never used it at all. Nearly half of the respondents administered metamizole i.v. in doses of 15 mg/kg body weight or lower, whereas 26% administered doses of at least 16 mg/kg up to more than 20 mg/kg. Of the physicians, 298 (20.2%) restricted the duration of metamizole use, varying between one single administration (4.7%), administration for 1 day (27.5%), or for 1-2 weeks (29.2%). Of the anesthesiologists, 65.6% reported no metamizole-related adverse effects. Allergic reactions/anaphylaxis and a drop in blood pressure requiring intervention were observed by 3-4% of the respondents. No change in blood cell counts within the last 2 years was reported by 73.1% of the respondents, whereas 17 anesthesiologists (1.3%) had observed children with altered blood cell counts, with 2 (0.14%) reporting agranulocytosis. In most cases these were incidental findings. No severe sequelae or deaths were reported. Few respondents (5.5%) performed routine blood cell counts to monitor metamizole therapy. Furthermore, only a minority always (3.5%) or sometimes (6.1%) informed a child's parents of possible side effects of treatment with metamizole.

CONCLUSION: The survey confirmed that metamizole is frequently used in children in the perioperative setting. Intravenous metamizole is the preferred nonopioid analgesic administered intraoperatively for pain prophylaxis. Clinical symptoms of agranulocytosis should be monitored and patients should be better informed about metamizole-related side effects.