ackground : Respiratory failure being the most common cause of death in acute organophosphorus poisoning has been known to develop due to acute cholinergic effect, but it may persist after disappearance of acute cholonergic symptoms and may also
develop
after acute cholinergic period. Atropine and PAM have been used as an antidote in the treatment of acute organophosphorus poisoning, but it has been recognized that they could not prevent
the development of respiratory failure that ocurs after acute cholinergic period.
Method : 94 patients with acute organophosphorus poisoning have been studied
retrospectively by the authors at the Pohang Sunlin Presbyterian Hospital from Jan 1988 to
Dec 1992. Of this number, 19 patients with respiratory failure were evaluated.
Results :
1) Among the exposed organophosphates in 19 patients with respiratory failure, fenthion
was the most common in 5 cases, dichlorvos in 3 cases, demeton in 2 cases, phenthoate and
edifenphos each in 1 case and unknown agents in 7 cases.
2) Mean time to onset of the respiratory failure was 22.2±20.1 hours (range from 1 to 77
hours) and mean time to recovery of the respiratory function in 7 cases who received
respiratory support for protracted period was 9 days (range from 5 to 16 days).
3) Serum cholinesterase activity on arrival had no significant difference between patients
with and without respiratory failure (22.5% vs 34.4% of normal subjects).
4) Mean dose of PAM administered within first 24 hours had no significant difference
between patients with and without respiratory failure (1.35±1.01 g vs 1.02±1.21 g). Mean
dose of atropine administered within first 24 hours was significantly higher in patients with
than patients without respiratory falure (48.75±37.58 mg vs 22.71±29.45 mg).
5) 12 patients among a total of 94 patients expired, so that the mortality rate was 12.8%.
Among the expired cases, 6 patients discontinued treatment due to economic problems and
only 6 patients died in hospital during the treatment.
Conclusion : These results suggest that respiratory failure in acute organophosphorus
poisoning may develop without any cholinergic symptoms and has no correlation with serum
cholinesterase activity. Atropine and PAM could not prevent the development of respiratory
depression, so that establishment of airway and respiratory support should be done in all
cases of respiratory failure.
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