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Diagnosis & Treatment — Hospital

 

Autopharmacological effects

S  Signs & Symptoms
  • Abdominal colic, vomiting, diarrhoea,
  • angio-oedema,
  • dyspnoea, bronchospasm,
  • arterial hypotension and shock.
D  Diagnostics

Clinical.

T  Treatment
  • Treatment of the anaphylactic/anaphylactoid shock,
  • possibly antivenom.
S  Signs & Symptoms

Generalised tissue oedema (increased capillary permeability!).

D  Diagnostics

Clinical.

T  Treatment
  • Antivenom,
  • treatment of the hypovolaemia/hypovolaemic shock.
S  Signs & Symptoms
  • Non-cardiogenic pulmonary oedema,
  • cerebral seizures (cerebral oedema),
  • (increased capillary permeability!).
D  Diagnostics
  • Clinical,
  • physical investigations:
    • chest X-ray,
    • CT.
T  Treatment
  • Antivenom,
  • treatment of the non-cardiogenic pulmonary oedema/cerebral oedema.
C  Comments

In most cases the cause of autopharmacological reactions is the direct toxin-induced release of biogenic amines. Immediate hypersensitivity reactions (type I) appear to be rare.

Species of snakes in the Far East that cause autopharmacological effects

C  Comments

The venoms of Protobothrops flavoviridis and Daboia russelli in particular can cause hypotensive shock within minutes after the bite and hypovolaemic shock within hours (note that such reports are primarily from Myanmar). The most common cause of death from Protobothrops flavoviridis bites is shock (Sawai 1989).

Local effects

S  Signs & Symptoms
  • Local swelling that can extend to the trunk,
  • local signs of haemorrhage (ecchymosis),
  • long-term sequelae: necrosis that can involve the subcutaneous tissue and musculature,
  • external eye: conjunctivitis, corneal lesions, uveitis.
D  Diagnostics
  • Clinical:
    • extent and intensity of the swelling,
    • inspection of the eyes (spitting cobras!).
  • Split lamp, fluorescein stain (spitting cobras!).
T  Treatment
  • Antivenom:
    • as long as there are concurrent signs of systemic envenoming,
    • if extensive or rapidly progressive swelling is present, especially with snakebites from those species known to cause necrosis.
  • Symptomatic treatment:
    • fluid replacement if there is extensive or rapidly progressive swelling. 
C  Comments

Tourniquets can cause local swelling and thus mimic local venom effects.

For some species of snakes local signs of envenoming, in particular swelling, are a reliable parameter for possible systemic envenoming, while for other species they provide no indication at all.

The efficacy of antivenom with regard to local effects, such as swelling and necrosis, is also controversial in the Far East.

Species of snakes in the Far East that cause local signs of envenoming

C  Comments

Necrosis develops after Cobra bites: N. atra, but also Ophiophagus hannah; and after crotalid bites: Gloydius sp., Deinagkistrodon acutus, Trimeresurus sp. (in the old taxonomic sense). Especially marked necrosis with large tissue defects and permanent severe functional impairment has been described in Japan (Amami Islands) following Protobothrops flavoviridis bites and in Taiwan following Deinagkistrodon acutus bites.

Compartment syndrome

D  Diagnostics
T  Treatment

Treatment of the compartment syndrome (see surgical literature).

C  Comments

There are no reports from the Far East of compartment syndrome.

The decision to perform a fasciotomy must have a rational basis (evidence of increased intra-compartmental pressure; reduced or absent arterial blood flow).

Haemostatic effects

S  Signs & Symptoms
  • Bleeding from injuries (apart from bite wounds),
  • bleeding into the skin (ecchymosis, petechiae),
  • gingival bleeding, epistaxis,
  • haematemesis, haemoptysis, bleeding per rectum, including melaena, haematuria (macro/micro),
  • clinical signs of shock (haemorrhagic shock!),
  • acute abdomen (intra-abdominal bleeding!),
  • flank pain/renal bed sensitive to percussion (ischaemia, renal haemorrhage!),
  • focal neurological signs, meningismus (intracranial bleeding!),
  • blue sclerae (anaemia due to bleeding!).
D  Diagnostics
  • Clinical,
  • laboratory parameters:
    • Hb, Hct,
    • clotting time,
    • PT/aPTT,
    • TT,
    • fibrinogen,
    • FSP,
    • D-dimers,
    • platelets,
    • blood group/blood sample for cross-matching.
T  Treatment
  • Antivenom.
  • Symptomatic treatment:
    • Whole blood.
    • Replacement of clotting factors and platelets following antivenom administration to bridge the gap until the antivenom starts being effective, insofar as evident bleeding or the imminent threat of critical bleeding makes this necessary. Also in cases where antivenom is not available or is ineffective and bleeding or the risk of bleeding makes intervention necessary (Warrell 1990b). However, it is important to note that replacement of clotting factors and platelets is only effective in the short-term while circulating haemostatically active venom components are still present. 
    • Treatment of the haemorrhagic shock.

Species of snakes in the Far East that cause haemostatic defects

C  Comments

The haemostatic defects caused by crotalids in the Far East are primarily due to direct activation of fibrinogen ("thrombin-like" activity), while those caused by D. russelli are due to procoagulative venom components (DIC).

Haemolytic effects

S  Signs & Symptoms
  • Icterus,
  • anaemia.
D  Diagnostics
  • Clinical,
  • laboratory parameters:
    • Hb, Hct,
    • free haemoglobin in the plasma and urine,
    • haptoglobin,
    • blood group/blood sample for cross-matching.
T  Treatment

Blood transfusion.

C  Comments

Even coagulation disorders that are severe according to laboratory tests may only be clinically apparent to a slight degree, or not at all. There is a threat of spontaneous haemorrhage with extensive loss of blood or focal bleeding (e.g. intracranial) as long as the haemostatic defect exists (untreated, i.e. without antivenom treatment, days to weeks). The risk is even greater if a patient does not receive appropriate treatment at a hospital and is then exposed to trauma, even very minor trauma, for example while working.

Loss of large volumes of blood can occur due to blood oozing from the bite wound or from injuries or due to medical or paramedical intervention.
If antivenom is effective, spontaneous systemic bleeding should cease within 1530 min, and blood coagulability should be restored within 1
6 h. The clotting time test is a simple means to regulate the antivenom dose. The initial dose should be repeated if the blood is still not coagulable 6 h after the first dose (Warrell 1990b).

If antivenom treatment is not successful, it is necessary to consider the possibility of misidentification of the snake that caused the bite, especially if monospecific antivenoms were used.

Species of snakes in the Far East that cause haemolysis

No reports are available.

Neurological effects

S  Signs & Symptoms
  • Cranial nerve paralysis, such as ptosis, opthalmoplegia, dysphagia, dysarthria.
  • Paralysis of the skeletal musculature, including the respiratory musculature, with respiratory insufficiency/respiratory failure.
D  Diagnostics
  • Clinical,
  • physical investigations:
    • blood gas analysis,
    • forced expiration test (peak expiratory flow).
T  Treatment
C  Comments

The efficacy of the currently available and clinically tested antivenoms with regard to neurological effects is not very convincing and, if present at all, is slow to occur (Watt 1992). If the neurological symptoms persist for longer than 30 min after the initial dose, a further dose should be given (Warrell 1990b).

At the same time, it is always necessary to consider the possibility of misidentification of the snake that caused the bite (see below), especially if monovalent antivenoms were used.

Due to the highly questionable efficacy of antivenom against neurotoxic symptoms of envenoming, the other two available treatment approaches need to be used concurrently and in a timely manner:

  • Endotracheal intubation and artificial respiration: endotracheal intubation is certain to prevent any form of aspiration. Manual or mechanical ventilation, even though it may have to be employed over a long period of time, can ensure survival of a patient with neurotoxin-induced respiratory failure.
  • The edrophonium (Tensilon®) test should be performed immediately in every patient with signs of paralysis, in order, if the result is positive, to make the most of the improvement in neuromuscular transmission that can be achieved through use of a longer-acting acetylcholinesterase inhibitor (neostigmine) (Watt 1992).

Species of snakes in the Far East that cause neurological effects

Muscular effects

S  Signs & Symptoms
  • Muscle pain,
  • tenderness of the musculature on pressure,
  • resistance to passive stretch,
  • pseudotrismus,
  • dark-brown/red urine (differential diagnosis haemoglobinuria).
D  Diagnostics
  • Clinical,
  • laboratory parameters:
    • myoglobin in the serum/urine,
    • serum creatinine kinase (CK, CPK),
    • GOT (AST),
    • serum potassium,
    • serum phosphate,
    • serum calcium.
T  Treatment
  • Antivenom,
  • symptomatic treatment:
    • prevention of myoglobinuric nephropathy,
    • immobilisation (regeneration of the damaged musculature).

Species of snakes in the Far East that cause rhabdomyolysis

Gloydius sp. ? (China, Korea).

Cardiac effects

S  Signs & Symptoms
  • Cardiac dysrhythmias,
  • cardiac insufficiency/failure.
D  Diagnostics
  • Clinical,
  • blood pressure, pulse,
  • ECG.
T  Treatment
  • Antivenom,
  • symptomatic treatment.
C  Comments

Cardiac dysrhythmias and cardiac insufficiency and failure are usually secondary effects (hyperkalaemia from various causes; in the context of shock).

Species of snakes in the Far East that cause cardiac effects

There are no data available.

Renal effects

S  Signs & Symptoms
  • Flank pain, renal bed sensitive to percussion,
  • eyelid oedema,
  • oliguria/anuria, polyuria.
D  Diagnostics
  • Clinical,
  • urine output (balance, hourly),
  • laboratory parameters:
    • serum creatinine,
    • serum potassium,
    • serum bicarbonate.
T  Treatment
  • Antivenom,
  • symptomatic treatment:
    • treatment of the acute renal failure.

Species of snakes in the Far East that cause renal effects

C  Comments

Acute renal failure is the most common cause of death from Gloydius blomhoffii bites (Sawai 1989).

With Daboia russelli and Rhabdophis sp. bites, acute renal failure is most probably primarily associated with renal ischaemia resulting from DIC. Periods of arterial hypotension also play a role.

However, a direct nephrotoxic effect of Daboia russelli venom has also been discussed (Ratcliffe et al. 1989).

How is the appropriate antivenom chosen?

D  Diagnostics
C  Comments

Difficulties arise if only monospecific antivenoms are available and the snake that caused the bite needs to be identified at the species level in order to be able to choose the appropriate antivenom.

In the majority of cases the snake is not available for identification or the patient's description of the snake is not conclusive.

Differentiation according to symptom complexes can aid regional identification (see Clinical flowchart: The Far East):

 

Signs of paralysis of the cranial nerves, extremities and respiratory musculature with no or minimal local effects:

 

Signs of paralysis of the cranial nerves, extremities and respiratory musculature, sometimes with marked local effects:

 

Haemostatic defects (abnormal clotting time) with spontaneous bleeding and local effects:


Local effects, hypotensive shock in the early phase (bleeding?) (clotting time normal):

 

If the selected antivenom is not effective, 3 possible causes need to be considered:

  1. correct identification of the cause, but insufficient dose administered;
  2. correct identification of the cause, but inadequate efficacy of the antivenom;
  3. incorrect identification of the cause → revision of identification.

How are antivenoms administered and complications caused by antivenoms treated?

T  Treatment

Monitoring of the patient

1. After administration of antivenom (assessment of success of antivenom or indication for continued antivenom treatment)

D  Diagnostics

Specific examinations are based on the signs and symptoms as well as laboratory parameters that were used to determine the indications for antivenom administration.

Viperids (D. russelli), crotalids (several Trimeresurus sp. in the old taxonomic sense, Deinagkistrodon acutus), colubrids (Rhabdophis sp.):

Elapids (Naja sp., Bungarus sp.), crotalids (Gloydius blomhoffii):

  • spontaneous breathing,
  • signs of respiratory insufficiency,
  • fist grasp,
  • upward gaze,
  • forced expiration test.

Other crotalids (Protobothrops flavoviridis, Gloydius sp.):

  • See Biomedical database entries.
C  Comments

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 due to continued absorption of venom from a depot in the region of the bite.

Patients bitten by species of snakes whose venom causes haemostatic defects should be kept in hospital for up to several days after initial treatment, and blood coagulability should continue to be monitored twice daily.

The same considerations apply to patients suffering from elapid bites.

2. If there is no indication for antivenom treatment following the initial investigation

D  Diagnostics

At least hourly:

  • state of consciousness,
  • ptosis,
  • heart rate and rhythm,
  • blood pressure,
  • respiratory rate,
  • bleeding,
  • local swelling,
  • other newly appearing signs and symptoms.

6-hourly (or more frequently if there is cause for suspicion):

Follow-up
1. Wounds, in particular necrosis

D  Diagnostics
  • Inspection,
  • bacterial smears.
T  Treatment
  • Excision of necrotic material,
  • surgical debridement under general or regional anaesthesia, 
  • skin grafting (split-thickness).

2. Contractures and other forms of impairment or loss of function of the extremities

D  Diagnostics

Clinical.

T  Treatment
  • Physiotherapy,
  • surgical correction.

3. Eyes (corneal lesions)

D  Diagnostics
  • Split lamp,
  • fluorescein stain.
T  Treatment

Local treatment.

4. If antivenom was administered: serum sickness

D  Diagnostics
T  Treatment