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Snake envenomation :snake: - Coggle Diagram
Snake envenomation :snake:
Australian elapid snakes [Family Elapidae]
Venom composition
Prothrombin-activating enzymes
Diffuse intravascular thrombosis
Consumptive coagulopathy
Lipases - phospholipases (PLA2)
Damage cell membrane
H2O influx
Spherocytosis [haemolytic]
Myolysis
Peptidic neurotoxins
Progressive flaccid paralysis
Weakened reflexes; ataxia; ptyalism
Ventilatory failure
Diagnosis
Clinical signs
Flaccid paralysis ; fine tremors; laboured breathing
Jaundice
Excess Hb excreted via kidneys
Haematuria
Myoglobin ; Hb
Clin path
Coagulopathy
:arrow_down: fibrin; :arrow_up: FDP
Prolonged clotting variables: :arrow_up: ACT; OSPT; APTT
Biochem
:arrow_up: CK; :arrow_up: AST
VDK+ve - rapid enzyme immunoassay
Pathogenesis
Haemotoxic
Haemorrhagic toxins
Prolonged coagulation --> haemorrhage
Procoagulant [QLD]
Factor Xa-like prothrombin activator
Severe: venom-induced activation of coagulation cascade (VICC)
Anticoagulant
Phospholipase A2 toxins
Antivenom reversal
Inhibit clotting facors
Spontaneous haemorrhage
Coagulation cascade
Haemolytic toxins
:hocho: erythrocytes
Haemolysis --> anaemia
H2O influx
Hyperbilirubinaemia (jaundice)
Spherocytosis
:dog2: higher sensitivity
CVS
Acute thrombotic obstruction
Procoagulant action
:arrow_down: Systemic arterial bp
:arrow_up: pulmonary bp
Myocardial ischaemia
Direct acting myotoxins
Inhibit myocardium Ca2+ channels
Arrhythmias
Neurotoxic
Pre-synaptic
Blocks ACh release
Unresponsive to antivenom
Post-synaptic
Ach receptor antagonist
Reversible antivenom
Progressive LMN flaccid paralysis
Ventilatory failure
Myolytic - muscle breakdown
PLA2 enzymes
cell membrane + organelles damage
Ca2+ influx -cell death
Cell contents released into bloodstream
Rhabdomyolysis --> renal failure
Creatinine Kinase (CK) efflux
Secondary renal failure
Filtration of Hb and Mb
Precipitation + nephron blockage
Acute renal failure
Accumulation toxicity
Procoagulant - fibrin microthrombi
Glomerular capillaries deposit
Ischaemia
Acute renal failure