Saeed Akram, Tussadiq Khurshid.
Successful Revival of Neurotoxic Snake Bite by Artificial Ventilation and Anticholinesterases.
J Coll Physicians Surg Pak Jan ;10(7):267-9.

Envenomation after a neurotoxic snake bite causes reversible nature of muscle weakness resembling myasthenia gravis. Respiratory muscle paralysis causing ventilatory failure may occur after envenomation. We report two cases of neurotoxic snake bite. Muscular weakness was gradual in onset in one case while the other showed a dramatic onset of respiratory paralysis. Anti-snakevenom was administered to both the cases. The patient with mild symptoms showed subjective improvement after oral anticholinesterases while the patient with respiratory paralysis was successfully revived by artificial respiration and intravenous anticholinesterases.

CASE REPORT: Case No. 1: A 40 years old clerk was sleeping when snake bit him on thumb at 0220 hours on 06-07-99. He immediately woke up and saw that a snake was creeping beside him and escaped. He felt pain at site of bite but there was no local reaction, only two fang marks were barely visible. He was admitted in ward for observation. At 1100 hours, about 09 hours after bite, ptosis was observed that was bilateral but more marked on right. There was no local reaction and no ooze at the site of bite. Hundred ml of polyvalent anti-snake-venom were infused in 500m1 of 5% dextrose. At 1330 hours patient started complaining of difficulty in swallowing.He remained fully conscious, but was unable to fully protrude the tongue. There was no difficulty in respiration. Tablet pyridostigmine (mestinon) 60mg TDS was started. Patient had subjective improvement in his symptoms of swallowing. The ability to cough also improved. There was significant improvement in ptosis and endurance of upward gaze. Patient complained that after initial improvement his symptoms reappeared before the next dose. The dose interval was then decreased to qid. His ptosis and difficulty in swallowing gradually decreased and he was discharged symptom-free on 12-07-99. The investigations carried out were all within normal limits.

Case No. 2: A 30 years old Sepoy was admitted in POF Hospital with story of bite by an unknown agent at 0930 hours on 24-07-99. He felt severe pain and burning sensation at the site of bite, which immediate) became swollen. Injection Solucortef l-6 100mg, Injection Phenergan 50mg I/M and Injection TT were given in emergency and he was referred to medical specialist.He was attended one-and-a-half hour after bite in medical OPD when he complained of pain at the site of bite, nausea and vomiting, and difficulty in breathing. There were fans marks on dorsum of right foot surrounded by swelling on dorsum of foot with redness extending up to right lower leg. There was no ooze from the site of bite. Although the patient did not see the snake, however, fang marks and local reaction was suggestive of snake bite. (Later on the snake was traced, killed and identified to be a cobra.) Cuffed endotracheal tube was passed later and patient was .On his way to the ward he collapsed in the corridor. He initially had laboured breathing and then went into apnoea within minutes. He was immediately brought to ITC where patient was initially put on ventilator. Initially ventilator was set on volume controlled mode with 100% oxygen at a tidal volume of 600m1 and respiratory rate of 20 breaths/minutes. Hundred ml of ventilated with Ambu bag and mask. Polyvalent anti-snake venom were infused in 500 ml of 5% dextrose. During infusion his blood pressure remained stable but he had a generalised rash. The swelling extended up to lower thigh and a few blisters appeared on the dorsum of foot. There was no bleeding from the site of bite or the venepuncture sites. Injection Neostigmine 1mg and Injection Atropine 0.5 mg infusion was started at a rate of 10 a drops per minute. Since the patient vomitted during resuscitation Injection ceftriaxone was also started. His investigations revealed PT 17 sec, PTTK 39 sec, TLC 10000 per ml while serum urea, electrolytes, creatinine and liver enzymes were within normal limits. Patient was monitored with ECG/B.P and pulse oximeter; Urine out put was also monitored. Patient was sedated with Midazolam and Morphine infusions. Since arterial blood gases facility was not available, patient was assessed periodically clinically and ventilator parameters were adjusted accordingly and percentage of OZ was reduced to 50% after some time. Later on when some respiratory effort came back, patient was switched over to synchronized intermittent mandatory ventilation mode (SIMV) at a rate of 12/minute. After almost 8 hours of artificial respiration his level of consciousness improved which was indicated by opening of eyes spontaneously and later on by verbal command. After 10 hours of artificial ventilation when patient`s condition improved, he was weaned off the ventilator by gradually decreasing the respiratory rate. When the swelling extended up to the thigh and necrosis appeared at the site of bite, infusion of 100 ml of polyvalent antisnake venom was repeated. Neostigmine and atropine infusion was tapered off next day. He was discharged from hospital symptomfree except for a mild swelling and pain on dorsum of foot.

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