Suspected snakebite in children: a study of 156 patients over 10 years

Abstract

MJA 1996; 164: 467  

Introduction

Our aim was to describe the presenting features, treatment and outcome in children with suspected snakebite attending an emergency department. We also examined aspects of the use of the Venom Detection Kit, which was widely used as an adjunct in the diagnosis and management of these children.  

Methods

To ensure all records were found, multiple data sources were accessed, including hospital morbidity coding for inpatient admissions; intensive care unit records; and emergency department records. Data extracted from the records were entered onto a Microsoft Access 2.0 database to assist with analysis.⁵

To facilitate a comparison with the study in adults from Perth hospitals,⁴ data on patients' snakebite history and envenomation status were extracted and patients were grouped in the categories listed in the Perth study⁴ and shown in Box 1.

Systemic envenomation was deemed present if there was clinical (vomiting, abdominal pain, or neurotoxic effects -- ptosis, convulsions, or difficulty with breathing or swallowing) or laboratory evidence (coagulopathy, haemolysis, rhabdomyolysis or renal failure).

Results

Age and sex distribution
The mean age of the children was six years and eight months (range, 15 months to 14 years 4 months), and over two-thirds (68%) were boys. Athough there was an even age distribution among children who were envenomed, there were 46 (29%) toddlers (less than three years) among the children presenting.

Location
Most snakebites occurred in the victims' garden (59 cases; 38%) or surrounding suburban bushland (51 cases; 33%). Eight (5%) occurred in a house or outbuilding and 26 (17%) children were bitten in open country. The location of the remaining 12 (7%) was not specified.

Seasonal distribution
Most children presented in the summer months, with very few presentations during winter; only three of the 14 children who were envenomed were bitten outside the months of October to April.

Bite site
Most children were bitten on a limb (lower limb: 103 cases, 66%; upper limb: 43 cases, 28%). There was one bite to the torso and one to the head, with the site not recorded in eight cases. Puncture marks were noted in 81 cases (52%).

First aid
It was often difficult to determine from the patient records whether first aid had been applied. However, in 39 cases it was clearly documented that no first aid was used, and inappropriate first aid (such as washing the site or use of an arterial tourniquet) was recorded in 10 cases (i.e., at least 49 children [31%] did not have effective first aid). The pressure- immobilisation first aid technique was used in 75 children (48%), although in some it was noted that the bandage had been applied only loosely or the limb was not fully immobilised. There was no record of whether first aid was applied in 32 children (21%). In some cases first aid measures were inappropriately left in place for a prolonged period after reaching hospital.

Envenomation
Fourteen children had systemic envenomation and 17 possible systemic envenomation according to the criteria used in this study (Box 1). The details of the clinical features, management and outcome of the 14 envenomed children are summarised in Box 2. In two children with possible envenomation, laboratory coagulation tests gave values just outside the normal range; both had an uneventful course and were not given antivenom. Four other child ren classified with possible envenomation received antivenom early for non-specific symptoms, without confirmatory laboratory evidence of envenomation.

Venom detection
Of the 117 cases in which the Venom Detection Kit was used, a positive result was obtained in 21 children (12 from wound swabs, 10 from urine, and four from blood). In nine of these child ren with no evidence of systemic envenomation, venom was detected in urine in five, and in skin swabs in the other four. In a child with borderline coagulopathy, the Venom Detection Kit gave a positive result in blood, but a negative one in urine. Another child treated for possible envenomation tested positive for venom at the "bite site", but tests of urine and blood gave a negative result with the Venom Detection Kit (Case D under "Use of antivenom").

The venom type detected by the Venom Detection Kit in envenomed patients is shown in Box 2.

Use of antivenom
Antivenom was given to 18 children (polyvalent in eight cases, brown snake in seven and tiger snake in five; two patients received more than one type of antivenom). Four children who were given antivenom may not have been envenomed.

Case A: An eight-year-old boy with a witnessed bite received antivenom for regional lymphaden o pathy and headache. No venom was detected at the bite site, nor in blood or urine.

Case B: A 10-year-old girl (no snake was seen) had a negative result of a Venom Detection Kit test of a bite site, and urine and coagulation studies showed no abnormality, but she was given antivenom because of symptoms of tiredness and non-specific weakness.

Case C: A nine-month-old girl who was crying and vomiting and noted to have a mark on her arm was given polyvalent antivenom before transfer to Princess Margaret Hospital. No venom detection tests were undertaken. Her symptoms of fever and intermittent vomiting were subsequently thought to be due to a viral illness.

Case D: A six-year-old girl had tiger snake venom detected at a possible bite site (but no venom detected in blood or urine). She was given tiger snake antivenom for symptoms of headache, fever, abdominal pain and nausea. A groin abscess was noted the next day, which may possibly have been the cause of her illness.

Other supportive treatment
Three children were administered fresh frozen plasma. No child required artificial ventilation.

Outcome
All children were discharged well from hospital; no permanent morbidity was recorded.  

Discusssion

Patterns of envenomation and treatment for snakebite in Perth children were similar to those reported previously in adults.⁴ The sex distribution of victims, the seasonal pattern of envenomation and the site of bites were also similar.

The venoms of the two snake genera responsible for most bites in Perth, Pseudonaja (brown snake) and Notechis (tiger snake), have powerful procoagulants, and coagulopathy was present in most (71%) of the envenomed patients. Among Perth snakes, only the tiger snake produces myolysis, and only one patient in this series had rhabdomyo lysis. Despite local differences in fauna, these findings are very similar to those in children with snakebite in Victoria.³

Despite continuing confirmation of the great efficacy of the pressure-immobilisation first aid technique in delaying venom spread,^6,7 it is disturbing that this method is still not being used widely. In many cases it is also being applied incorrectly. More public education on first aid in snakebite is needed.

The role of the Venom Detection Kit in patients with suspected snakebite attending emergency departments is discussed in Box 4.

Although it appeared that no child came to harm after discharge from the Emergency Department, this practice is fraught with danger, as a case from 1973 illustrates. A two-year-old girl with restlessness and dry retching presented to hospital with an unclear history; the possibility of snakebite was raised by the parents. The examining medical officer concluded that she had been bitten by an insect, no investigations were ordered and she was discharged. The next morning she was found dead in bed, and it was later confirmed that tiger snake envenomation had been the cause of death. The Coroner found that there had been a lack of care on the part of the hospital, contributing to her death.¹⁰

In most children presenting to an emergency department there is no way of determining absolutely whether a venomous snakebite has occurred. There are special difficulties in obtaining a reliable history from young children and it may be tempting to use a negative result of a Venom Detection Kit to facilitate early discharge. Indeed, a number of children in this study were discharged from the Emergency Department without laboratory investigations, apart from use of the Venom Detection Kit. However, all children in whom snakebite is suspected, whether a snake was seen or not, should be admitted to hospital for observation and investigation (including coagulation profiles). In a number of cases of envenomation in our series, no snake bite was observed, and in two cases no snake was seen. Discharging children with suspected snakebite directly from emergency departments without a period of observation is not recommended.  

References

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