Management of Incapacitating Agent Exposure

Anticholinergic incapacitating agents such as 3-quinuclidinyl benzilate (BZ) cause hyperactivity and confusion, which must be controlled as quickly as possible to 

Physostigmine (a naturally occurring carbamate anticholinesterase compound extracted from the Calabar bean) may be used as an antidote to the effects of BZ. It should be administered intravenously with care in severely affected patients in doses of 2-4 mg given at hourly intervals. 

Knockdown agents are a special form of incapacitating agent which rapidly produces an anaesthetic-Uke state following inhalation. There is one substantiated case of such agents being used in the civil setting, namely the 2002 Moscow Theatre incident, where the Russian special forces claimed they used a powerful opiate compound (a fentanyl). Fatalities occurred from respiratory failure and arrest (see Chap. 10). 

In the management of an opiate knockdown agent exposure, early airway and ventilation assessment is essential and intermittent positive pressure ventilation with 100 % oxygen should start as soon as possible if there is a respiratory failure. An antidote to the respiratory depression caused by opiates is naloxone which is used both in anaesthetic and clinical toxicological practice. This is given in doses of 0.4 mg IV repeated until there is a reversal of the respiratory depression. It should be noted that in cases of mixed injury where opioids may have been given for pain relief, the analgesic effect will also be reversed. 

Artificial ventilation must be continued while naloxone is being administered until the patient has a sufficient respiratory effort. This can be detected clinically and by using a portable ventilator with a demand function set to continuous mandatory ventilation (CMV) demand. The Moscow theatre incident (see Chap. 10) showed the lethal effects of opioids on respiration and the dangers of relying on antidote therapy alone. 

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