[Evaluation of charcoal hemoperfusion in dogs with acute fluoroacetamide poisoning]

In the past the mortality and sequelae rate of the patients with severe fluoroacetamide (FAM) poisoning treated only with traditional remedies was high. During the recent ten years the authors treated children with severe FAM poisoning with charcoal hemoperfusion (HP) and achieved better results. However evidence was not sufficient to show that reduced mortality and sequelae rates were obtained from HP without traditional treatment because of lack of prospective randomized, controlled clinical studies. Thus, a dog model for FAM poisoning was designed in order to study the therapeutic effect, high-efficiency time of HP, the time of tissue-poisoning to release after HP, and to investigate the toxicokinetics of the poison in the course of treatment and after HP.

Fourteen dogs were given intraperitoneal FAM at a dose of 0.3 mg/kg body weight. HP was performed on 9 poisoned dogs for 30 - 120 minutes post intoxication. Each procedure lasted for 4 hours. Blood samples of the 9 poisoned dogs were collected before HP and 30, 60, 90, 120, 180, 240 minutes during HP and 2, 6, 24 hours after HP. Blood plasma was separated from blood samples and stored at -20 degrees C. The concentration of the poison was measured by gas chromatography (GC). The clinical symptoms of all the dogs were observed for one day.

The FAM concentration (ng/ml) of blood samples in poisoned dogs before HP, and 60, 120, 180, 240 minutes during HP were 230.11 +/- 52.48, 184.56 +/- 62.57, 141.00 +/- 44.83, 126.78 +/- 61.04, 113.11 +/- 54.65 respectively. The differences were significant (chi(2) = 31.978, P < 0.0005). The dispersion count between pre-HP and HP for 1 was 45.55, between 1 h and 2 h was 43.56, between 2 h and 3 h was 14.22 and between 3 h and 4 h was 13.67. The values of FAM had declined by 38.7%, 45.0% and 50.8% respectively at 2 h, 3 h, 4 h of HP compared with pre-HP. The rate of cleaning efficacy of FAM of every hour during HP were 19.79%, 23.6%, 10.09% and 10.78% respectively during HP 1, 2, 3, 4 h. The cleaning efficacy of HP was high within 2 hours during HP. The concentration of FAM slightly rose again 6 h after HP. The level of FAM had declined at 24 hour after HP when compared with pre-HP level. The reduction rate of FAM level for every hour during HP was higher than that after HP (12.71% vs 0.27% - 2.22%). The t(1/2) of FAM with and without HP were (4.50 +/- 1.20) h and (49.60 +/- 10.56) h. All the 5 poisoned dogs not treated with HP died. However 6 poisoned dogs treated with HP kept alive after HP. Three dogs had frequent seizures again 4h after HP. After HP the charcoal container was washed by 0.9% saline and FAM could not be detected in the douche.

Charcoal HP was an effective treatment for severe FAM poisoning. T(1/2) of the poison was shortened, and the poison clearing rate was accelerated by HP. The high-efficiency time of HP was 2 - 2.5 h. Activated charcoal can adsorb the poison vigorously, and return of blood to the body after HP by using 0.9% saline was feasible and safe.