Snakebite	71

Dhruva Chaudhry, Inder Paul Singh, and Surcharita Ray

A 20-year-old male patient presented with history of diffuse abdominal pain, myalgias, difficulty in swallowing, and pooling of secretions. He also complained of difficulty in breathing and diplopia with acute onset drooping of eyes. He was conscious, oriented to time and space, with a respiratory rate of 12/min and a single breath count of 12. The power in all limbs was 4/5, but all reflexes were absent. He had ptosis, and the rest of the general and systemic examination was normal. He was absolutely normal the previous night, when he had slept on the floor.

Some snakebites result in envenomation. Most of the snakes are nonvenomous. The outcome of snakebite depends on numerous factors which include species of snake, the area of the body bitten, and the amount of venom injected.

Step 1: Initial resuscitation and assessment

Airway

•Management of airway is very important in snakebite.

•The patient should be assessed for any pooling of secretions or respiratory depression with a single breath count of less than 10 and if present should be immediately intubated following the general indications of intubation.

D. Chaudhry, M.D., D.M. (*)

Department of Pulmonary & Critical Care Medicine, Pt. B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, India

e-mail: [e-mail]

I.P. Singh, M.D., D.N.B.

Department of Pulmonary Medicine, Vallabhbhai Patel Chest Institute, New Delhi, India

S. Ray

Department of Medicine, Pt. B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, India

R. Chawla and S. Todi (eds.), ICU Protocols: A stepwise approach,	567
DOI 10.1007/978-81-322-0535-7_71, © Springer India 2012

568	D. Chaudhry et al.

Breathing

•The patient’s oxygenation status can be monitored with a bedside pulse oximeter.

•When the patient is in respiratory distress and not able to maintain oxygenation, he/she should be put on assisted ventilation.

Circulation

•Obtain a good peripheral line and start intravenous fluids.

•Be careful while venipuncturing in patients with coagulopathy.

Step 2: Take detailed history

•Detailed history such as the type of the snake color, length, timing of bite, provoked or unprovoked bite, and first-aid measures done should be taken.

•Patients with snakebite usually present with history of sudden onset of generalized weakness, with diplopia, difficulty in swallowing, pooling of secretions, ptosis, abdominal pain, and diffuse myalgias.

•Ask for local swelling or pain in the body and bleeding from any site including cardiovascular collapse.

Step 3: Perform physical examination

•A comprehensive general physical and neurological examination should be performed in all patients with suspected snakebite.

•The examination may reveal generalized motor weakness with sluggish deep tendon reflexes.

•There may be ptosis and both internal and external ophthalmoplegia giving a false impression of brain stem dysfunction. However, the patient responds to commands by using the frontalis muscle and orbicularis oculi.

•Usually, there are no local reactions in neuroparalytic snake envenomation (krait); however, in cobra bite, severe local reaction can be seen.

•The differential diagnosis of any patient presenting with sudden onset of neurological deficit with respiratory compromise is enumerated in Table 71.1.

Table 71.1 Differential diagnosis of acute neurological weakness

Acute inflammatory demyelinating polyradiculoneuropathy (AIDP, i.e., LGB syndrome)

Transverse myelitis

Periodic paralysis (hypokalemic, hyperkalemic, normokalemic)

Acute myasthenic crisis

Organophosphorus poisoning

Hypomagnesemia and hypophosphatemia

Hypoglycemia

Acute intermittent porphyrias

Polymyositis/dermatomyositis

Tick paralysis

Head/spinalcord injury

71 Snakebite		569
Table 71.2 Severity of snakebite
Severity	Local findings	Systemic findings
Nonenvenomation	None or puncture wounds only	None
(dry bite)
Mild	Puncture wounds, pain, soft tissue	None
	swelling confined to the bite site
Moderate	Swelling beyond bite site	Mild nausea, vomiting or fascicula-
		tions, paraesthesia, microscopic
		hematuria
Severe	Severe pain and swelling	Respiratory failure or hypotension
		or bleeding

•Look for features of local inflammation and if present on the status of circulation.

•Bleeding from the site may be the first manifestation of envenomation.

•Look for hematuria, epistaxis, hematemesis, and ecchymosis.

•Look for blood pressure and carefully follow and monitor.

Step 4: Severity of snakebite

Once a diagnosis of snakebite is made, the patient should be assessed for the severity, as enumerated in Table 71.2.

Step 5: Order investigations

•Complete hemogram with platelet counts, bleeding time (BT), coagulation time (CT), and clot retraction time (CRT) at 20 min or alternately slide test for observing coagulation of blood.

•Urine examination—RBCs in the absence of gross hematuria.

•Prothrombin time, INR, PTTK, fibrinogen level, creatinine kinase, fibrin degradation product, D-dimer.

•If urine is smoky and RBCs absent, look for myoglobulin to rule out myoglobinuria.

•Blood urea and serum creatinine levels should be regularly monitored in patients with renal failure.

•Serum electrolytes and blood gas analysis.

Step 6: Admit to the ICU

• Indications of ICU admission are mentioned in Table 71.3.

Step 7: General management

•All the patients should receive antitetanus toxoid, and the local wound should be cleansed with soap and water.

•The limb with the bite mark should be immobilized; however, no tourniquet should be tied.

•Keep the bitten limb lower than the heart as far as possible.

•Open the tourniquet, if applied outside, only when resuscitative measures are underway.

•Patients with mild features should be observed for at least 24 h.

570	D. Chaudhry et al.

•Do not apply ice to the bite site.

•Routine use of antibiotics is not recommended.

Step 8: Specific management

Antisnake venom

•Antisnake venom (ASV) is prepared from horses’ serum.

•It can be monovalent or polyvalent.

•One milliliter of reconstituted antivenin neutralizes 0.6-mg venom of Indian cobra and Russell’s viper and 0.45 mg of common krait and saw-scaled viper.

•If the patient tolerates the ASV, then patients are usually given 50–100 mL of reconstituted ASV in serious envenomation as an infusion over 1 h, after premedication with chlorpheniramine maleate (5 mg) and ranitidine (50 mg).

•It can also be given as push especially when the patient is bleeding profusely at the rate not more than 2 mL/min.

•Patients with moderate and severe envenomation should be given a test dose of ASV intradermally.

•Patients should be observed for any reaction to the ASV.

•ASV will not have a dramatic effect in neuroparalysis. Low-dose ASV is as effective as high dosage in neuroparalytic snake envenomation.

•ASV will however have dramatic effect in stopping bleeding in coagulation abnormalities.

•The patient should be regularly assessed for any signs of reaction to ASV.

•ASV should be given till the patient has no bleeding manifestation or platelet counts rise above 50,000 and resolution of paralysis.

Step 9: Watch for reaction

•ASV is a foreign protein. Therefore, allergic reactions including anaphylaxis are not unknown.

•An adrenaline syringe should always be kept ready before infusing ASV.

•In case the patient is sensitive to ASV or develops reaction to ASV during infusion, first stop the infusion of ASV.

•It should be followed by adrenaline—usual recommended dosage is 0.5 mg of 1:1,000 dilutions subcutaneously.

•Additional dosages of H1 (chlorpheniramine maleate) and H2 (ranitidine) blockers with hydrocortisone 100 mg, though later will take 4–6 h to act, should be given simultaneously.

•If needed, adrenaline can be repeated up to two to three dosages or an infusion can be started in dilution of 1:50,000.

•Hypotension is treated with fluids. Inotropes may be required in patients who had overt myocardial dysfunction.

Step 10: ICU management

•Initiate mechanical ventilation at appropriate time as it reduces the mortality significantly in neuroparalytic envenomation.