Clinical management of envenoming and poisoning
This section describes the general circumstances of accidents with venomous and poisonous animals. Important questions regarding medical care of envenoming and poisoning are discussed.
The following questions are discussed in the "Essentials of the management of envenoming and poisoning":
- Is the situation a medical emergency?
- Does a specific and effective first aid method exist?
- What level of identification of the animal that caused the accident is necessary?
- What level of identification of the animal that caused the accident can be achieved if the animal is not available for morphological identification?
- Which strategy guarantees the best conditions for first aid, diagnosis and treatment if the animal is not available for morphological identification?
- What level of identification of the animal that caused the accident can be achieved if the animal is available for morphological identification?
- Which strategy guarantees the best conditions for first aid, diagnosis and treatment if the animal has been conclusively identified taxonomically?
- How is clinically relevant envenoming or poisoning recognised?
- How is the appropriate antivenom chosen? When is it administered?
- What is expected of an ideal antivenom?
- How reliable is the information regarding first aid, diagnosis and treatment on which the recommendations for managing accidents with venomous or poisonous animals are based?
- Which venomous or poisonous animal caused the accident?
Identification of the animal groups
Identification of venomous and poisonous animal group helps to reduce the great number of possible causes of envenoming or poisoning.
The following groups of venomous and poisonous animals are distinguished (see detailed key):
Main components of the VAPAGuide for the animal groups
In the Emergency flowcharts the acute symptoms of envenoming are listed, along with the corresponding emergency medical treatment, medically relevant animals and available antivenoms. White boxes indicate only rare or questionable evidence in this particular region. The path to the choice of appropriate antivenom(s) is shown. The Emergency flowcharts serve the following purposes:
- orientation within a group of venomous or poisonous animals,
- initial emergency medical treatment of patients in whom envenoming/poisoning is already advanced, and
- rapid determination of appropriate antivenom(s).
In the Emergency flowcharts there is a distinction between animals for which there is a good deal of evidence regarding envenoming/poisoning (grey boxes) and those about which little is known (white boxes). Naturally the well-studied animals are also those that are most likely to cause an accident. In the Emergency flowchart there is also a link to the WHO-Antivenom list and MAVIN-Antivenom index in which all the commercially available antivenoms are listed.
The Clinical flowcharts show the course of envenoming for all medically significant venomous/poisonous animals on the group level. The overall effect of a particular venom/poison is divided here into seven primary venom/poison effects (see below). Possible organ failures mark the end points of the progress of envenoming/poisoning in the Clinical flowcharts. Click on white boxes to see information on the specific venom/poison effect!
Diagnosis & Treatment
With the aid of the information and recommendations in these sections, it should be possible to solve the basic medical problems posed by an accident with a venomous or poisonous animal. This core information regarding the diagnosis and treatment of envenoming/poisoning at the group level is linked to all the other sections of the VAPAGuide, in order to provide necessary additional information whenever required. The diagnostic-therapeutic strategy of the VAPAGuide is problem-oriented.
Description of the signs and symptoms of envenoming has been systematised, in that the overall effect of each venom/poison is divided into seven primary venom/poison effects:
- autopharmacological effects,
- local effects,
- haemostatic effects,
- neurological effects,
- muscular effects,
- cardiac effects,
- renal effects.
This breakdown of the venom effects is repeated in the Clinical flowcharts and clinical Biomedical database entries.
The Biomedical database contains the best available evidence on small taxonomic units (families, genera, species, subspecies) regarding
- Clinical features, diagnosis and management.
The Biomedical database should be consulted in parallel with the Diagnosis & Treatment chapters in order to obtain more detailed information (e.g. on the efficacy of a certain antivenom). Furthermore, it contains information that enables more precise identification of the animal that caused the accident.
The structure of the Biomedical database entries is
Clinical features, diagnosis and management:
- Citation of studies and case reports and the criteria used to identify the culprits,
- Signs and symptoms of envenoming/poisoning indicated in the studies and case reports,
- Morbidity and mortality,
- Results of laboratory and physical investigations,
- Study findings with regard to first aid, symptomatic and specific treatment (antivenoms).
Annex: How to manage a snake bite
The identification keys are based on easily observable and accessible criteria. They enable laypersons to identify a dead venomous snake at the genus level.
The distribution tables list the species of snakes that occur in each country. With the help of these tables the range of species that may have potentially caused an accident can be narrowed down.
The biological tables contain information regarding the habitat, appearance, behaviour and factors relevant to envenoming for the important venomous snakes in a specific region. Together with the Distribution tables, the biological tables are an important aid in narrowing down the species of snake that caused the bite when it is not available for identification.
Annex: First aid and symptomatic treatment measures
There is information on first aid in the Diagnosis & Treatment section for each group of animals. The problems accompanying first aid measures are described, in some depth with regard to the terrestrial snakes.
The diagnosis and treatment of compartment syndrome are explained briefly. This problem is dealt with in a separate section because, from experience, errors of judgment in this context can lead to severe and even permanent damage that could otherwise have been avoided.
The scope of application of these substances is described. A treatment diagram assists with their use in clinical practice.
The information on antivenom treatment is summarised in the two treatment diagrams "Antivenom administration: practical approach" and "Antivenom reactions: types, mechanisms, treatment". They are valid for all the animal groups. These data are presented in table form to enable fast access to information on the essential treatment steps.
Annex: Background information
This section describes the fundamental principles of haemostasis and its diagnostic evaluation with regard to the specific issues in accidents with venomous and poisonous animals.
From experience, there are frequently difficulties with the choice, application and interpretation of haemostatic tests, and this section provides advice "in an emergency".
The seven primary venom/poison effects are described in detail.
Biological taxonomical nomenclature tends to be difficult for laypersons. In this section, the taxonomic classification system is explained, so that terms such as genus, species, subspecies etc. are correctly used and understood.