Perioperative analgesia with intraoperatively started infusion of high-dose dipyrone in orthopaedic and trauma surgery

Metamizole-associated adverse events: a systematic review and meta-analysis

Background

Metamizole is used to treat pain in many parts of the world. Information on the safety profile of metamizole is scarce; no conclusive summary of the literature exists.

Objective

To determine whether metamizole is clinically safe compared to placebo and other analgesics.

Methods

We searched CENTRAL, MEDLINE, EMBASE, CINAHL, and several clinical trial registries. We screened the reference lists of included trials and previous systematic reviews. We included randomized controlled trials that compared the effects of metamizole, administered to adults in any form and for any indication, to other analgesics or to placebo. Two authors extracted data regarding trial design and size, indications for pain medication, patient characteristics, treatment regimens, and methodological characteristics. Adverse events (AEs), serious adverse events (SAEs), and dropouts were assessed. We conducted separate meta-analyses for each metamizole comparator, using standard inverse-variance random effects meta-analysis to pool the estimates across trials, reported as risk ratios (RRs). We calculated the DerSimonian and Laird variance estimate T² to measure heterogeneity between trials. The pre-specified primary end point was any AE during the trial period.

Results

Of the 696 potentially eligible trials, 79 trials including almost 4000 patients with short-term metamizole use of less than two weeks met our inclusion criteria. Fewer AEs were reported for metamizole compared to opioids, RR = 0.79 (confidence interval 0.79 to 0.96). We found no differences between metamizole and placebo, paracetamol and NSAIDs. Only a few SAEs were reported, with no difference between metamizole and other analgesics. No agranulocytosis or deaths were reported. Our results were limited by the mediocre overall quality of the reports.

Conclusion

For short-term use in the hospital setting, metamizole seems to be a safe choice when compared to other widely used analgesics. High-quality, adequately sized trials assessing the intermediate- and long-term safety of metamizole are needed.

Bradycardia and hypotension associated with fomepizole infusion during hemodialysis

We report a case of hypotension and bradycardia associated with intravenous fomepizole infusion.

CASE REPORT

A 59-year-old man presented to hospital 10 hours after ethylene glycol ingestion with ataxia, slurred speech, metabolic acidosis, heart rate 70/min, blood pressure 160/100 mmHg. Treatment with hemodialysis and fomepizole began 7.5 hours after admission. Severe bradycardia (29/min) and hypotension (69 mmHg systolic) occurred immediately following a 30 minute intravenous infusion of the first (19 mg/kg) fomepizole dose, but rapidly corrected with 1 mg atropine. Transient bradycardia (48/min) and hypotension (89/57 mmHg) recurred immediately after the second (10 mg/kg) fomepizole dose, also given during dialysis.

DISCUSSION

Hemodialysis may cause a drop in blood pressure and heart rate; however, the close temporal relationship with fomepizole infusions, dose-related symptom intensity and recurrence with rechallenge suggest a causal relationship with fomepizole. Hemodialysis, acidosis and high initial fomepizole dose may have enhanced patient susceptibility, as a post-dialysis fomepizole dose was well tolerated.

CONCLUSION

Fomepizole may precipitate bradycardia and/or hypotension during hemodialysis. Monitor vital signs closely during and immediately after infusion.

The treatment of pain in urology

Contemporary medicine is characterized by sophisticated specialization of the individual physician. The specialist in urological surgery may undertake one of the most important and primary medical tasks, the mitigation and therapy of pain. This review aims to provide an overview of the concepts of pain therapy in urology. Most patients benefit from basic concepts of analgesia, including measuring and documenting pain scores at the bedside by the nursing staff. Patients undergoing very painful operative procedures require more potent techniques of analgesia, e.g. intravenous patient-controlled analgesia and epidural analgesia. These techniques need adequate supervision by an acute pain service, but their implementation improves the outcome in some situations. Pain in acute renal obstruction varies in intensity and duration; hence, analgesic therapy has to be tailored to the individual patient. Pain syndromes from cancer can be more complex than those after surgery. Neuropathic pain is probably the most difficult to manage and requires consultation with a pain-management specialist. In the case of neuropathic pain, treatment only with opioids is of limited efficacy and combination with co-analgesics is necessary. In addition, invasive analgesic therapies should sometimes be considered.