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Best evidence topic report
Flumazenil and suspected benzodiazepine overdose
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  1. Pranay Kumar Singh,
  2. Katrina Richell-Herren
  1. Department of Emergency Medicine, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL

    http://dx.doi.org/10.1136/emj.17.3.214

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      Report by Pranay Kumar Singh, Medical Student Search checked by Katrina Richell-Herren, Research Fellow

      Clinical scenario

      An unresponsive young adult is brought to the emergency department. No history is available. Neurological examination reveals no focal abnormality and pupils are mid-size and reactive. Blood glucose is normal. You suspect an overdose and wonder whether flumazenil should be given to ascertain whether benzodiazepines are involved.

      Three part question

      In [patients with suspected overdose] is [a single dose of flumazenil] indicated to [safely diagnose benzodiazepine ingestion]?

      Search strategy

      Medline 1966–01/00 using the OVID interface. [({exp flumazenil OR flumazenil.mp} AND {exp overdoses OR overdoses.mp OR exp poisoning OR poisoning.mp}) AND {exp diagnosis OR exp diagnosis, differential OR diagnosis.mp OR diagnos$.mp}] LIMIT to human AND english.

      Search outcome

      Altogether 45 papers were found of which 39 were irrelevant or of insufficient quality.The remaining six papers are shown in table 3.

      View this table:
      Table 3

      Comments

      All the studies are small. Most are PRCTs investigating the use of flumazenil in the management of benzodiazepine overdose. These show that flumazenil improves conscious levels in patients who have taken overdoses. Significant adverse reactions occurred including fitting and transient increases in conscious level. Only the diagnostic study gives some idea of the clinical utility of the test.

      Clinical bottom line

      The sensitivity of a single dose of flumazenil is high enough to allow failure to respond to be used as a SnNout for benzodiazepine overdose. The specificity is too low to allow it to be used to rule-in. The possibility of mixed overdose is a relative contraindication to using flumazenil.

      Report by Pranay Kumar Singh, Medical Student Search checked by Katrina Richell-Herren, Research Fellow

      References

      1. Hojer J, Baehrendz S. The effect of flumazenil in the management of self-induced benzodiazepine poisoning. Acta Med Scand1988;224:357–65.
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      2. Ritz R, Zuber M, Elsasser S, et al. Use of flumazenil in intoxicated patients with coma. A double blind placebo controlled study in ICU. Intensive Care Med1990;16:242–7.
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      3. Hojer J, Baehrendz S. Diagnostic utility of flumazenil in comatose patients. BMJ1990;301:1308–11.
      4. Chern T, Hu S, Lee C, et al. Diagnostic and therapeutic utility of flumazenil in comatose patients. Am J Emerg Med1993;11:122–4.
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      5. Gueye PN, Hoffman JR, Taboulet P, et al. Empiric use of flumazenil in comatose patients: limited applicability of criteria to define low risk. Ann Emerg Med1996;27:730–5.
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      6. Barnett R, Grace M, Boothe P, et al. Flumazenil in drug overdose: randomized placebo controlled study to assess cost effectiveness. Crit Care Med1999;27:10–11.
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