Toxinology Flashcards
Funnel-web spider envenomation: signs and symptoms
Cholinergic - secretions, salivation, bronchorrhoea
+
Adrenergic - HTN, tachycardia, myocardial injury
+
Catecholaminergic carciac toxicity - MI, pulm oedema
+Neuromuscular:
Agitation, fasciculations, paraesthesias (local, distal and perioral)
Funnel-web spider envenomation: management and disposition
Antivenom x2 vials
- Signs of severe envenoming
- Move to resus
Pressure bandage
- Within 4 hours
- Remove only once antivenom commenced
Tetanus booster
Seek and support catecholamine-induced myocardial injury w/ inotropes
Observation:
- 4 hours after bite
- 2 hours after removal or pressure bandage
–> DC if well
Envenomation unlikely to develop after 2 hours
- If given antivenom, monitor 12-24 hours until signs and symptoms resolved
Redback spider toxin
Alpha-latrotoxin
Acts pre-synaptically to open cation channels (incl. Ca2+) and stimulate release of multiple motor end-plate neurotransmitters
Redback spider envenomation (Latrodectism): clinical features
Pain (primary feature)
- Local at bite site (increasing over mins->hours, can last days)
- Radiating to draining lymph nodes
- +non-specific abdo, chest, back
Local autonomic
- Local sweating
- Regional sweating w/ unusual distribution (e.g. bilateral below knees)
- Piloerection, erythema, paraesthesias, muscle spasms
Non-specific
- Malaise, lethargy
- N+V
- Irritability, agitation
- Fever
- Priapism
Redback spider: antivenom trials
RAVE 1: No difference between IV vs IM
RAVE 2: No clinical benefit vs analgesia
- Can cause adverse effects (e.g. mild hypersensitivity, serum sickness)
Redback spider envenomation: management
Anaglesia
DON’T pressure bandage
Tetanus booster
Discharge once pain well-controlled on oral analgesia (pain can last 5 days)
Snake bite: examination
- Bite site and regional lymphadenopathy
- Neuro: CN deficits + peripheral weakness
- Resp muscle weakness: VC/PEFR
- VICC: bleeding from gums/cannula site
- Myotoxicity: dark urine, muscle tenderness
Snake bite: Bloods
FBC and film
EUC
Coags, fibrinogen, D dimer
LDH
CK
Taken at:
Presentation, 1hr post-bandage removal, 6hrs, 12hrs
Snake bite: initial management (general)
- Pressure bandage + immobilisation (if <4 hrs)
- Resuscitation
- Bloods
- Early administration of antivenom if indicated
- FFP for VIC w/ bleeding (avoid if possible)
- Haemodialysis for thrombotic microangiopathy w/ renal failure
Antivenom will:
- Reverse anticoagulant coagulopathy + non-specific symptoms
- Prevent further development of other symptoms
Snake bite: when to remove pressure bandage
Antivenom given
OR:
- No evidence of envenomation clinically
- No sign of envenomation on bloods
- Monitored resus bed
- Local access to antivenom
Snake bite: discharge criteria
No envenomation:
- Bloods normal (at 0, 1hr post-bandage removal, 6hrs, 12hrs)
- No symptoms
- Normal neuro exam
Min 12hrs monitoring for all
Envenomation:
- Resolution of symptoms incl. NM paralysis
- Bloods show:
- No ATM (AKI, TTP, MAHA)
- Normal INR
- CK falling
Venom induced consumption coagulopathy (VICC) biochemistry
APTT - high or unrecordable
INR - high: >3 in complete, <3 in partial
D-dimer: high
Fibrinogen - low (partial) or undetectable
Antivenom: criteria and timing
Give on clinical features alone if symptoms of envenomation:
- Non-specific headache and vomiting
- Systemically unwell appearance
- Early cardiovascular collapse (hypotension, arrest, unconscious, seizures)
- Ptosis or blurred visison
Ideally given <2 hours
Give up to 12 hrs, no benefit >12
Repeat bloods 6, 12, 24 hours after given
Antivenom: which one when?
Most unidentified bites:
- 1x vial tiger snake monovalent
- 1x vial brown snake monovalent
Will cover: red-bellied black
Won’t cover: taipan, death adder
Tiger monovalent alone if:
- Definite red-bellied black
- In Tasmania
- Expert identification
- DW clinical tox or poisons
Polyvalent antivenom if:
- Significant doubt about snake type
- Likelihood of mulga, death adder or taipan
- Far northern Aus w/ VICC
Antivenom: monovalent vs polyvalent adverse effect rate (+polyvalent components)
Anaphylaxis or anaphylactoid reactions:
- Monovalent 1%
- Polyvalent 5%
Polyvalent:
- brown, tiger, black, death adder, taipan
Snake bite: signs and symptoms indicative of envenomation
Non-specific:
- N+V, headache, avbdo pain, diarrhoea, sweating
Significant local bite site effects
Early CV collapse (hypotension etc.)
Neurotoxicity:
- Ptsosis, blurred vision
- Descending flaccid paralysis
Myotoxicity
Coagulopathy
AKI
Brown snake envenomation: location and features
Mainland Aus
- Early CVS collapse
- VICC
- Thrombotic microangiopathy
- AKI
No myotox/neurotox
Tiger snake envenomation: location and features
Southern Aus incl. WA and Tas
EVERYTHING EXCEPT ANTICOAG
1. CV collapse
2. VICC
3. Myotox
4. Neurotox
5. Thrombotic microangiopathy
6. AKI
Same as taipan
Taipan envenomation: location and features
Northern Aus, mainly FNQ
EVERYTHING EXCEPT ANTICOAG
1. CV collapse
2. VICC
3. Myotox
4. Neurotox
5. Thrombotic microangiopathy
6. AKI
Same as tiger
Red-bellied black snake envenomation: location and features
Eastern Aus
BAM
1. Bite site pain
2. Anticoagulant coagulopathy
3. Myotoxicity
Same as mulga
Mulga snake envenomation: location and features
Mainland Aus but not eastern seaboard (opposite to RBB)
BAM
1. Bite site pain
2. Anticoagulant coagulopathy
3. Myotoxicity
Same as RBB
Death adder toxicity: location and features
Mainland Aus but not Vic
- Neurotoxicity - post-synaptic
- Local pain
Venom detection kit?
NOT used to determine envenomation
Can be used to guide choice antivenom
May have false positives
Not recommended to use - better assessment based on location, clinical syndrome
Snake envenomation: thrombotic microangiopathy biochemistry
Fragmented RBCs on film
Thrombocytopaenia
Cr >120
Raised LDH
Snake antivenom anaphylaxis
Some immediate hypersensitivity in 25% patients - urticaria, rash
Severe anaphylaxis in 2-3%
- Hypotension most common
Mx:
- Temporarily cease antivenom
- IM adrenaline if severe
- IVF, bronchodilators
- No role for pre-medication w/ adrenaline
Antivenom serum sickness: symptoms, timing and management
Fever, rash, arthralgia, myalgia, non-specific
4-14 days after administration
25-50mg PO pred for 7 days
Antivenom administration practicalities
Dilute 1:10 in NaCl 0.9%
Give IV over 15 mins
Only in resus bay w/ access to adrenaline
Only repeat dose after d/w tox
Warn about delayed serum sickness (4-14 days post)
Water animal wound management
- Remove stinger/spine
- Wash/irrigate well
- If marine, warm water (45degC) for up to 90 mins - Imaging - XR/US for FB
- Consider delayed closure or surgical washout and debridemenet
- Consider ABx covering marine infections - Doxy
- Tetanus booster
- Follow-up within 48 hours
Blue bottle management
Wash sting site with sea water (not fresh)
Remove tentacles
Immerse in hot water (45 degC) for 20 mins
- Alt. hot shower
NOT cold and NOT vinegar
Box jellyfish sting: clinical features
Local
- Immediate severe pain
- Delayed erythematous wheal
- Superficial necrosis (severe)
Systemic
- CV collapse (hypotension, arrest, LOC, seizures)
- Muscular paralysis
- Death in 20-30 mins
Box jellyfish sting: management
Remove tentacles
Vinegar + ice pack
Analgesia
If CVS collapse:
- CPR
- Box jellyfish antivenom (1 vial, 1:10 NaCl, over 15 mins)
- MgSO4 10mmol IV
Irukandji sting: clinical features
Local:
- Minor, can’t see sting site
Systemic (20-30 mins post):
- Severe generalised pain - back, abdo, chest, MSK
- Tachy + HTN
- Anxiety, agitation
- N+V
Irukandji sting: managment
Vinegar
Analgesia
ECG + trop (cardiotoxic)
Manage HTN - GTN, aim SBP <160 mmHg
Seek and treat CVS complications:
- APO
- ACS
- Takotsubo
?MgSO4 10mmol IV
NO ANTIVENOM
Stone fish sting: clinical features and management
Features:
- Pain++ at site
- Hypotension + CV collapse
- Paralysis
Mx:
- Hot water immersion - 45 deg, 90 mins
- Analgesia
- Wound care
- DON’T pressure bandage
- Stonefish antivenom if systemic symptoms
Stingray sting
Penetrating trauma
+
Tissue necrosis from venom
Mx:
Resus if thorax/abdo trauma
Hot water immersion (45degC for 90mins)
Analgesia
Wound care:
- Irrigation
- Consider surgical exploration/debridement
- Tetanus booster
- Consider ABx for marine wounds (cipro 500mg BD)
- Review wound in 24-48 hours
Blue ring octopus sting: clinical features
Tetrodotoxin = Na channel blockade
- PAINLESS bite
- Local numbness + tingling
- Descending flaccid paralysis
- CNs -> ptosis, diplopia, dysphagia
- Flaccid paralysis incl. resp muscles - Cardiorespiratory collapse
Blue ring octopus sting: management
Pressure bandage + immobilisation
Resuscitation
Intubate + ventilate
- Until resp paralysis resolves, usually 2-5 days
NO antivenom
Puffer fish or toad fish (ingestion)
Tetrodotoxin = Na channel blockade
- Facial numbness, descending paralysis
- GI upset
- Arrhythmias/CVS collapse
As per blue ring
No antivenom - supportive
I+V for 2-5 days
Atropine if bradycardic
Box jellyfish vs blue-ring octopus
Box jelly: mainly CVS collapse, can have paralysis
Blue-ring octopus/puffer: mainly paralysis, can have CVS collapse
Sea snake envenomation
- Myotox - rhabdo, spasms
- N+V, malaise
- Neurotox (rare, 2 cases)
Manage as per land snakes:
- Pressure bandage + immobilisation
- Resus
- Sea snake antivenom 1x vial
If sea snake antivenom not available, use TIGER snake monovalent
Sea urchin envenomation
Features:
Intense pain
Pigment may be visible in surrounding tissue
Systemic:
- N+V
- Paraesthesias, numbness
- Muscle paralysis
- Resp distress
- Hepatitis (uncommon)
Mx:
Hot water immersion
Remove spines
- Removal or buried spines not recommended, will resorb with time
XR for FB
Tetanus
Prophylactic ABx for deep injuries (cipro/doxy)
Cone snail toxin
Conotoxins
Potent neurotoxic peptides
Immediate pain –> progressive paralysis, perioral tingling –> resp failure/death
Mx:
Pressure immobilisation
Analgesia
Resus
Tetanus
NO antivenom
