OTHER INVESTIGATIONS

– Peak flow meter in patients (adolescents and adults) presenting with neuroparalytic syndrome.

– If Peak flow meter is not available in PHC then assess respiratory function using bedside tests - single breath count, breath holding time and ability to complete one sentence in one health as described earlier.

– Urine examination for albumin and blood by dipstick.

In addition to the above

– Prothrombin time

– Platelet count,

– Clot retraction time

– Liver function test (LFT)

– Renal Function test (RFT)

– Serum Amylase

– Blood sugar

– ECG

– Abdominal ultrasound

– 2D Echo (if available)

In addition to the above

In neuroparalytic envenomation

• Arterial blood gases. Caution: Arterial puncture is contraindicated in patients with haemostatic abnormalities.

• Pulmonary function tests

In Vasculotoxic venomation

• For coagulopathy- BT, CT, PT, APTT, Platelet, Serum Fibrinogen, FDP D-Dimer assay, LDH, peripheral blood smear

• Hemolysis -Urine for myoglobin, Urine haemoglobin

• For renal failure- Urine microscopy for RBC, casts, RFT, urinary proteins, creatinine ratio

• Hepatic injury – LFTs including SGOT, SGPT, Alkalien phosphatase, serum proteins

• Cardiotoxicity- CPK-MB, 2D Echo, BNP

• Myotoxic – CPK, SGOT, Urine myoglobin, compartment pressure

• Infection- Serum procalcitonin, culture (blood, urine, wound) and sensitivity

– Arterial blood gases and urine examination should be repeated at frequent intervals during the acute phase to assess progressive systemic toxicity).

Rationale and interpretation of the tests:

4. Hemogram: The hemogram may show transient elevation of hemoglobin level due to hemoconcentration (because of the increased capillary leak) or may show anemia (due to hemolysis, especially in viper bites). Presence of neutrophilic leucocytosis signifies systemic absorption of venom. Thrombocytopenia may be a feature of viper envenomation.

5. Platelet count: This may be decreased in victims of envenoming by vipers.

White blood cell count: An early neutrophil leucocytosis is evidence of systemic envenoming from any species.

Blood film: Fragmented red cells (“helmet cell”, schistocytes) are seen when there is microangiopathic haemolysis.

Plasma/serum: May be pinkish or brownish if there is gross haemoglobinaemia or myoglobinaemia.

6. Serum creatinine: This is necessary to rule out acute kidney injury after viper and sea snakebite.

7. Serum creatinine phosphokinase (CPK): Elevated levels of these markers suggests muscle damage (caution for renal damage) and raised amylase suggests pancreatic injury

8. Prothrombin time (PT) and activated partial thromboplastin time (aPTT): Prolongation may be present in viper bite (to be repeated 6 hourly, if abnormal).

9. Fibrinogen and fibrin degradation products (FDPs): Low fibrinogen with elevated FDP is present when venom interferes with the clotting mechanism.

10. Urine examination for Proteinuria/ RBC/ Haemoglobinuria/ Myoglobinuria: The colour of the urine (pink, red, brown, black) should be noted and the urine should be tested by dipsticks for blood or haemoglobin or myoglobin. Standard dipsticks do not distinguish blood, haemoglobin and myoglobin. Haemoglobin and myoglobin can be separated by immunoassays but there is no easy or reliable test. Microscopy will confirm whether there are erythrocytes in the urine.

11. Electrocardiogram (ECG): Nonspecific ECG changes such as bradycardia and atrioventricular block with ST-T changes may be seen.

12. Electroencephalogram (EEG): Recently, EEG changes have been noted in up to 96% of patients bitten by snakes. These changes start within hours of the bite but are not associated with any features of encephalopathy. Sixty-two percent showed grade I changes, 31% cases manifested grade II changes (moderate to severe abnormality), and the remaining 4% showed severe abnormality (grade III).These abnormal EEG patterns were seen mainly in the temporal lobes (Ramachandran S et al 1995). However, rarely needed for patient management.

13. Pulse oximetry for oxygen in patients with respiratory failure or shock.

14. Electrolyte determinations: These tests are necessary for patients with respiratory paralysis and systemic symptoms.

15. Arterial blood gases and pH may show evidence of respiratory failure (neurotoxic

16. X-Ray/ CT/ Ultrasound (The use of X-Ray and ultrasound are of unproven benefit, apart from identification of bleeding in Viperine bites).