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Poisonous animals
 
Cnidarians (Jellyfish, Corals and Anemones)
 
Venomous fish
 
Scorpions
 
Spiders
 
Hymenopterans (Bees, Wasps and Ants)
 
Sea snakes
 
Terrestrial snakes
 
Miscellaneous animals
 
 
 
 
 
 
 
 

Diagnosis & Treatment — General practitioner / health post

 

General problems

At particular risk are: children, elderly people, patients with pre-existing conditions, such as coronary heart disease, arterial hypertension, lung disease, kidney disease, allergies (sensitisation) and patients taking particular drugs, such as beta-blockers.

Patient presents with a tourniquet on the affected extremity

D  Diagnostics

Check venous and arterial blood supply in the extremity.

C  Comments

If a tourniquet has been applied, it should not be removed until antivenom is at hand and the means for treating complications, including possible complications caused by the antivenom, are available.

One case was reported in which a Hydrophiidae bite led to neurological symptoms and subsequent respiratory insufficiency after cessation of stasis in the lower leg, even though the child, who had been bitten by an Astrotia stokesii, was previously asymptomatic (Mercer et al. 1981).

Is it likely that a clinically relevant injection of venom has taken place?

D  Diagnostics

Inquire re:

  • time of the bite,
  • nausea, vomiting,
  • blurred vision, double images,
  • flank pain.

Assess:

  • state of consciousness.

Measure:

  • blood pressure/pulse,
  • respiratory rate,
  • urinary output.

Observe/investigate:

  • bite marks,
  • favouring of the affected limb (muscle pain),
  • signs of paralysis:
    • cranial nerve deficits, such as ptosis, ophthalmoplegia, dysphagia, dysarthria,
    • paralysis of the skeletal musculature including the respiratory musculature (→ respiratory insufficiency/respiratory failure),
  • pseudotrismus,
  • muscle spasms,
  • urine (dark, brown/black or red),
  • passive movement of the musculature painful,
  • muscle compression painful,
  • flank pain and renal bed sensitive to percussion.

Determine:

  • cause of the accident by detection of specific venom antigen,
  • venom concentration in the serum using the ELISA method (if clinically proven and standardised test kits are commercially available), 
  • arterial blood gases,
  • ECG (cardiac dysrhythmia, signs of hyperkalaemia).
C  Comments

The symptoms and degree of envenoming depend not only on the amount of venom injected and numerous other variables, but also on the time that has elapsed since the bite. This variable factor must be taken into account when making the following decisions:

  • exclusion of envenoming,
  • the time interval between clinical examinations,
  • emergency care.

The fact that a patient has been bitten by a sea snake and the presence of bite marks do not automatically allow the conclusion that a clinically relevant injection of venom has taken place [39 of 55 Enhydrina schistosa bites, 11/14 Hydrophis cyanocinctus bites and 6/9 Hydrophis spiralis bites did not involve a clinically relevant injection of venom (Reid 1975b)].

Local signs, such as swelling and pain at the site of the bite, are usually absent and thus completely unreliable as clinical indicators of an injection of venom.

There seem to exist 2 forms of Hydrophiidae envenoming with different courses:

  1. primarily myotoxic envenoming (e.g. Enhydrina schistosa): signs and symptoms arising in the skeletal musculature; secondary effects of rhabdomyolysis: dark urine (myoglobinuria), acute renal failure, cardiac dysrhythmias (hyperkalaemia);
  2. neurotoxic/(myotoxic) envenoming (e.g. Astrotia stokesii): initially prominent are acute neurotoxic symptoms that occur a short time after the bite and their corresponding signs: ptosis, ophthalmoplegia, dysphagia, dysphonia; progressive paralysis of the respiratory musculature with respiratory insufficiency and failure.

Exclusion of clinically relevant envenoming

D  Diagnostics

Monitoring for signs and symptoms (see above) that would indicate systemic envenoming for at least 12(–24) h (recommended examinations see Therapy phase: Hospital: Monitoring of the patient):

  • preparalytic phase: within minutes,
  • preclinical phase of effects of the venom on the skeletal musculature: 0.5–4 h (Reid 1979).
C  Comments

According to observations by Reid in Penang (Malaysia) severe envenoming can be excluded if there is no skeletal muscle pain upon movement 2 h after the bite (Reid 1979). However, these observations were made chiefly in patients who had been bitten by Enhydrina schistosa.

Who requires antivenom?

D  Diagnostics

Antivenom indications (overview)
Systemic signs of envenoming:

  • myalgia upon active or passive movement,
  • ptosis, ophthalmoplegia, dysphagia, dysarthria,
  • paralysis of the limb musculature,
  • paralysis of the respiratory musculature with respiratory insufficiency and failure,
  • myoglobinuria (dark, brown/black or red urine).
  • acute renal failure,
  • raised CPK, raised serum AST.

How is the appropriate antivenom chosen?

D  Diagnostics

How are antivenoms administered and complications caused by antivenoms treated?

T  Treatment
C  Comments

Symptomatic emergency medical treatment and antivenom treatment are complementary strategies.

The aim of antivenom treatment is neutralisation of the venom.

The success of antivenom treatment depends on the quality of the antivenom, the specific properties of those venom components relevant to envenoming and the time point at which antivenom is administered.

Symptomatic emergency medical treatment

S  Signs & Symptoms
  • Clinical signs of progressive paralysis of the skeletal musculature including paralysis of the respiratory musculature (→ dyspnoea, respiratory failure),
  • clinical signs of rhabdomyolysis with acute renal failure and hyperkalaemia (ECG).
T  Treatment
C  Comments

Symptomatic emergency medical treatment and antivenom treatment are complementary strategies.

The aim of symptomatic emergency medical treatment is the rapid correction of critical parameters (fluid balance, blood pressure, oxygenation etc.) and the maintenance of vital functions (respiratory, cardiovascular).

Symptomatic measures help bridge the gap until specific treatment (antivenom) can be administered and starts being effective. If no antivenom is available or if the required effect is not achieved with antivenom, the goal is to employ symptomatic measures until such time as the venom naturally starts losing its activity. 

Neostigmine appears to have been ineffective in the cases observed by Reid (1956, 1961a).

However, this does not exclude the possibility that it could be effective in those cases of Hydrophiidae envenoming in which the neurological effects of the venom are prominent (e.g. Astrotia stokesii).

Local treatment

Bite wound, including the surrounding reaction

D  Diagnostics

Assessment of the wound according to the usual criteria.

T  Treatment
  • Cleaning, disinfection and dressing of the wound at regular intervals.
  • Immobilisation of the extremity with a splint.
  • Possibly also prophylactic antibiotic treatment.

Tetanus

T  Treatment

Tetanus prophylaxis.