Diagnosis & Treatment — Hospital
Who requires antivenom?
Autopharmacological effects
- Abdominal colic, vomiting, diarrhoea,
- angio-oedema,
- dyspnoea, bronchospasm,
- arterial hypotension and shock.
Clinical.
Treatment of the anaphylactic shock.
On the basis of the cases of Hydrophiidae bites reported to date, it seems that autopharmacological effects are not an issue.
Local effects
From experience to date, local effects are typically absent.
Tourniquets can cause local swelling and thus mimic local venom effects.
Haemostatic effects
From experience to date, there are no haemostatic effects.
Neurological effects
- Cranial nerve paralysis (ptosis, opthalmoplegia, dysphagia, dysarthria),
- paralysis of the skeletal musculature, including the respiratory musculature (→ dyspnoea/respiratory failure).
- Clinical,
- physical investigations:
- respiratory rate,
- blood gas analysis,
- forced expiration test (peak expiratory flow).
- Antivenom,
- symptomatic treatment:
- endotracheal intubation and artificial respiration,
- edrophonium (Tensilon®)/neostigmine.
Muscular effects
- Favouring of the affected limb (muscle pain),
- myalgia upon active and passive movement,
- muscle compression painful,
- pseudotrismus,
- muscle spasms,
- urine dark, brown/black or red,
- diminished or absent grip and pinch strength (danger of aspiration; respiratory insufficiency/failure),
- acute renal insufficiency,
- hyperkalaemia (cardiac disturbances).
- Clinical,
- laboratory parameters:
- myoglobin in the serum/urine,
- CPK,
- AST (GOT),
- serum potassium,
- serum phosphate,
- serum calcium,
- ECG (signs of hyperkalaemia).
- Antivenom,
- symptomatic treatment:
- prevention of myoglobinuric nephropathy,
- immobilisation (regeneration of the damaged musculature).
The venom of some species of Hydrophiidae (E. schistosa (=Hydrophis schistosus)) contains myotoxic phospholipase A (Fohlman and Eaker 1977), which dominates the course of envenoming caused by these species (Reid 1961a, 1975, 1979). It induces rhabdomyolysis. Only the skeletal musculature appears to be affected.
For the clinical course and classification of severity see E. schistosa (=Hydrophis schistosus).
Cardiac effects
- Cardiac dysrhythmias,
- cardiac insufficiency and failure.
- Blood pressure, pulse,
- serum potassium,
- ECG (signs of hyperkalaemia, cardiac dysrhythmias).
- Antivenom,
- treatment of the hyperkalaemia.
From experience to date, the cardiac effects caused by Hydrophiidae envenoming appear to be secondary in nature.
Rhabdomyolysis and acute renal failure induce hyperkalaemia and related cardiac sequelae.
Renal effects
- Flank pain, renal bed sensitive to percussion,
- eyelid oedema,
- oliguria/anuria, polyuria.
- Clinical,
- urine output (balance, hourly),
- laboratory parameters:
- serum creatinine,
- serum potassium,
- serum bicarbonate,
- ECG.
- Antivenom,
- symptomatic treatment,
- treatment of acute renal failure, including dialysis.
From experience to date, the nephrological effects caused by Hydrophiidae envenoming appear, at least in large part, to be secondary in nature.
The acute renal failure occurs in the context of the rhabdomyolysis. Histological investigations following autopsy and biopsies resulted in the finding of distal tubular necrosis (Marsden and Reid 1961, Reid 1979, Sitprija et al. 1971).
Dialysis: apart from the acute renal insufficiency, dialysis also improved the skeletal musculature symptoms (Sitprija et al. 1971).
How is the appropriate antivenom chosen?
- See Emergency flowchart: Sea snakes,
- see the MAVIN Antivenom index,
- see the Biomedical database entries for additional information.
How are antivenoms administered and complications caused by antivenoms treated?
See Antivenom treatment.
If the administration of antivenom is not effective, 2 possible causes need to be considered:
- Correct identification of the cause, but insufficient dose administered.
- Correct identification of the cause, but inadequate efficacy of the antivenom. However, according to in vitro and in vivo investigations (Baxter and Gallichio 1974, 1976) and clinical experience (Reid 1962, 1975a, b, Mercer et al. 1981, Audley 1985, Fulde and Smith 1984), the efficacy of the available antivenoms and their cross-reactivity appear to be good.
Monitoring of the patient
1. After administration of antivenom (assessment of success of antivenom or indication for continued antivenom treatment)
Specific examinations are based on the signs and symptoms as well as laboratory parameters that were used to determine the indications for antivenom administration.
Even if the desired effect of antivenom administration, namely normalisation of the parameters relevant to envenoming (findings on physical examinations, physical and laboratory investigations), is achieved quickly, this does not mean that the symptoms of envenoming may not re-occur (Mercer et al. 1981), possibly due to continued absorption of venom from a depot in the region of the bite.
2. If there is no indication for antivenom treatment following the initial investigation
At least hourly:
- state of consciousness,
- ptosis, dysphagia, dysphonia,
- heart rate and rhythm,
- blood pressure,
- respiratory rate,
- myalgia upon active or passive movement,
- urine colour (myoglobinuria),
- other newly appearing signs and symptoms,
- the following laboratory parameters are highly sensitive: serum AST, CPK,
- ECG (hyperkalaemia).
Follow-up
1. Wounds
- Inspection,
- bacterial smears.
2. Following rhabdomyolysis
- Bed rest/physical rest,
- physiotherapy.
Overstretching and tearing of the sarcolemmal sheaths, which are apparently not affected by the myonecrosis, must be prevented in order to ensure regeneration of the muscle fibres that pass through these structures (Reid 1979).
The duration of the illness following a Hydrophiidae bite with rhabdomyolytic effects can be estimated in the following manner: each day on which myoglobin is detectable in the urine means the duration of the illness will be prolonged by a week (Reid 1979).