Investigating pressure bandaging for snakebite in a simulated setting: bandage type, training and the effect of transport

Harm due to the use of pressure bandage immobilisation in patients bitten by snakes in Australia

BACKGROUND

Pressure bandage immobilisation has remained the recommended first aid treatment for more than 40 years in Australia. However, whilst it is used in most people bitten by a snake, it is often applied poorly, and patients have been envenomed despite good pressure bandage immobilisation. We report two patients who suffered harm from this procedure.

CASE REPORTS

Two men, a 35-year-old and a 44-year-old, were bitten by snakes. Both had a prompt application of pressure bandage immobilisation, and both reported significant pain requiring opioid analgesia whilst being transferred from remote Australia to Cairns Hospital, Queensland. There were substantial delays (9.5 h and 7.5 h) before the pressure bandage immobilisation was released. As a result, both patients developed severe rhabdomyolysis (33,600 U/L and 16,800 U/L [normal < 171 U/L], respectively); there was no evidence of systemic envenoming. The 35-year-old developed a compartment syndrome that required urgent and repeated surgery. The 44-year-old has ongoing foot paraesthesia two years after the bite.

CONCLUSION

With limited good evidence of benefit, and many issues with its use, I recommend that pressure bandage immobilisation as a first aid measure for snakebite in Australia needs to be re-examined.

Snakebite Treatment in Tanzania: Identifying Gaps in Community Practices and Hospital Resources

Snakebite envenoming causes more than 140,000 deaths annually and at least triple this number of disabilities. The World Health Organization classified snakebite as a Neglected Tropical Disease in 2017 and developed a strategy to halve death and disability from snakebite by 2030. To achieve this goal, snakebite victims need to receive safe and effective treatment. This descriptive, cross-sectional study surveyed student health professionals (N = 312) in Dar es Salaam, Tanzania, and was designed to identify major gaps in community practices and hospital resources for snakebite treatment. Participants reported using traditional community practices (44%, 95% confidence interval (CI) = 39–50%), allopathic practices (7%, 95% CI = 5–11%), or a combination of both (49%, 95% CI = 43–54%) to treat snakebite. Harmful practices included tight arterial tourniquets (46%, 95% CI = 41–52%) and wound incisions (15%, 95% CI = 11–19%). Many participants (35%, 95% CI = 29–40%) also turned to traditional healers. Students who treated snakebite injuries within the last 5 years (N = 69) also reported their general experiences with snakebite in hospitals. Hospitals often lacked essential resources to treat snakebite victims, and 44% (95% CI = 30–59%) of snakebite victims arrived at a hospital only three or more hours after the bite. A significant percentage of snakebite victims experienced lasting damage (32%, 95% CI = 20–47%) or death (14%, 95% CI = 7–25%). Snakebite outcomes could likely be improved if hospitals were universally and consistently equipped with the essential resources to treat snakebite victims, such as antivenoms. Educational interventions aimed at communities should focus on discouraging tourniquet use and tampering with the wound. Collaboration between the allopathic and traditional health system could further boost snakebite outcomes because traditional healers are often the first health workers to see snakebite victims.

An assessment of medical students' proficiency in the diagnosis and management of snakebites: a cross-sectional study from Palestine

BACKGROUND

Snakebites are emergent and life-threatening injuries that may require intensive care. Physicians face difficulties in dealing with snakebite injuries due to the knowledge gaps in the diagnosis and management of snakebites. The study aimed to assess medical students' knowledge about the diagnosis and management of snakebite injuries, as well as their proficiency in first aid methods in case of snakebite and perception regarding snakes and snakebite injuries.

METHODS

A cross-sectional study conducted among 200 medical students in their clinical years at An-Najah National University. A questionnaire was developed and distributed among those students. The questionnaire assessed the students' knowledge regarding the diagnosis and management of snakebites and their attitude regarding snakes and snakebites. The total scores of knowledge were obtained and tested based on the participants' demographic characteristics using the Kruskal-Wallis test and the Mann-Whitney U test. P-values of < 0.05 were considered to be statistically significant.

RESULTS

The mean age of participating medical students was 22.2 ± 2.4 (year). Half of these medical students were in there final year of study (sixth year). After the analysis was done, we found a knowledge deficit in snakebite diagnosis and management among medical students. The mean knowledge scores regarding Vipera palaestinae, signs and symptoms, laboratory investigations, anti-venom, and first aid were 3.8/13, 8.2/16, 6.1/10, 3.6/11 and 8.3/15 respectively for medical students. It was found that medical students in higher years of study had a higher knowledge of laboratory investigation, and males were more knowledgeable in the correct way for first aid methods than females (p < 0.036).

CONCLUSIONS

The level of knowledge regarding the diagnosis and management of snakebites was not good enough among most of the students. In order to improve their knowledge, snakebite diagnosis and management should be introduced and focused on in medical curriculum. Also, formal first aid training classes for medical students should be introduced in order to teach them the correct and updated methods of first aid as they will be the future health care providers and proper first aid will effectively decrease morbidity and mortality of snakebites.

Two pathways for venom toxin entry consequent to injection of an Australian elapid snake venom

Here we test and refute the hypothesis that venom toxins from an Australian elapid, the Eastern Brown snake (Pseudonaja textilis, PTx), solely require lymphatic transport to enter the circulation. Studies were made using anaesthetised non-recovery rats in which a marker dye (India ink) or highly potent PTx venom was injected into the hind paw. The studies required a means of inhibiting lymphatic function, as achieved by cooling of the test hind limb to low temperatures (~3 °C). Maintained entry of a non-lethal dose (0.15 mg/kg) and respiratory arrest consequent to injection of a lethal dose (1 mg/kg) of PTx venom at these low temperatures indicate that venom including toxin components enter the circulation directly via the vascular system, a process facilitated by, but not dependent on, lymphatic transport. Notably, the venom had a direct effect on vascular permeability markedly increasing this to allow extravasation of plasma albumin (MWt ~60 kDa).

First Aid and Pre-Hospital Management of Venomous Snakebites

BACKGROUND

Antivenom is the definitive treatment for venomous snakebites, but is expensive and not available in many rural and poorly developed regions. Timely transportation to facilities that stock and administer antivenom may not be available in rural areas with poorly developed emergency medical services. These factors have led to consideration of measures to delay onset of toxicity or alternatives to antivenom therapy.

METHODS

PubMed searches were conducted for articles on snakebite treatment, or that contained first aid, emergency medical services, tourniquets, pressure immobilization bandages, suction devices, and lymphatic flow inhibitors.

RESULTS

The reviewed articles describe how venoms spread after a venomous snakebite on an extremity, list the proposed first aid measures for delaying the spread of venoms, and evaluate the scientific studies that support or refute methods of snakebite first aid. The recommendations for field treatment of venomous snakebites will be discussed.

CONCLUSIONS

The evidence suggests that pressure immobilization bandages and related strategies are the best interventions to delay onset of systemic toxicity from venomous snakebites but may increase local toxicity for venoms that destroy tissue at the site of the bite, so their use should be individualized to the circumstances and nature of the venom.

Snakebite: When the Human Touch Becomes a Bad Touch

Many issues and complications in treating snakebite are a result of poor human social, economic and clinical intervention and management. As such, there is scope for significant improvements for reducing incidence and increasing patient outcomes. Snakes do not target humans as prey, but as our dwellings and farms expand ever farther and climate change increases snake activity periods, accidental encounters with snakes seeking water and prey increase drastically. Despite its long history, the snakebite crisis is neglected, ignored, underestimated and fundamentally misunderstood. Tens of thousands of lives are lost to snakebites each year and hundreds of thousands of people will survive with some form of permanent damage and reduced work capacity. These numbers are well recognized as being gross underestimations due to poor to non-existent record keeping in some of the most affected areas. These underestimations complicate achieving the proper recognition of snakebite’s socioeconomic impact and thus securing foreign aid to help alleviate this global crisis. Antivenoms are expensive and hospitals are few and far between, leaving people to seek help from traditional healers or use other forms of ineffective treatment. In some cases, cheaper, inappropriately manufactured antivenom from other regions is used despite no evidence for their efficacy, with often robust data demonstrating they are woefully ineffective in neutralizing many venoms for which they are marketed for. Inappropriate first-aid and treatments include cutting the wound, tourniquets, electrical shock, immersion in ice water, and use of ineffective herbal remedies by traditional healers. Even in the developed world, there are fundamental controversies including fasciotomy, pressure bandages, antivenom dosage, premedication such as adrenalin, and lack of antivenom for exotic snakebites in the pet trade. This review explores the myriad of human-origin factors that influence the trajectory of global snakebite causes and treatment failures and illustrate that snakebite is as much a sociological and economic problem as it is a medical one. Reducing the incidence and frequency of such controllable factors are therefore realistic targets to help alleviate the global snakebite burden as incremental improvements across several areas will have a strong cumulative effect.

Snakebites in Africa and Europe: a military perspective and update for contemporary operations

Snakebite envenoming is rare among military patients, with few cases reported in recent years. Increasingly, however, military operations are taking place in remote parts of Africa, which are inhabited by numerous species of venomous snake, and in Europe, where dangerous species exist but are less common. Bites from a venomous snake may prove fatal, and therefore military medics must be adequately prepared to manage them. This paper reviews the most medically significant species of venomous snake present in Africa and Europe, before suggesting an evidence-based approach to snakebite prevention and management, including possible changes to the UK's Clinical Guidelines for Operations.

The Treatment of Snake Bites in a First Aid Setting: A Systematic Review

Background

The worldwide burden of snakebite is high, especially in remote regions with lesser accessibility to professional healthcare. Therefore, adequate first aid for snakebite is of the utmost importance. A wide range of different first aid techniques have been described in literature, and are being used in practice. This systematic review aimed to summarize the best available evidence concerning effective and feasible first aid techniques for snakebite.

Methods

A systematic literature screening, performed independently by two authors in the Cochrane Library, MEDLINE and Embase resulted in 14 studies, fulfilling our predefined selection criteria, concerning first aid techniques for snakebite management. Data was extracted and the body of evidence was appraised according to the GRADE approach.

Principal findings

The pressure immobilization technique was identified as the only evidence-based first aid technique with effectiveness on venom spread. However, additional studies suggest that proper application of this technique is not feasible for laypeople. Evidence concerning other first aid measures, such as the application of a tourniquet, suggests avoiding the use of these techniques.

Conclusions

The practical recommendation for the treatment of snakebite in a first aid setting is to immobilize the victim, while awaiting the emergency services. However, given the low to very low quality of the data collected, high quality randomized controlled trials concerning the efficacy and feasibility of different variations of the pressure immobilization technique are warranted.

The Belgian Red Cross-Flanders develops first aid guidelines that specifically target laypeople. In the context of updating the first aid guidelines for sub-Saharan Africa, we aimed to summarize the best available evidence for the treatment of snakebite, feasible for laypeople. Of the numerous first aid measures supported in literature and used in practice, we could only find evidence concerning effectiveness for the pressure immobilization technique on the spread of snake venom, which involves application of a firm pressure bandage on the bitten limb, together with immobilization of the limb. However, studies concerning its feasibility suggest this technique is difficult for laypeople to apply correctly. Keeping the limb immobilized on the other hand had a beneficial effect on the spread of the venom. However, given the low to very low quality of the evidence, high quality trials concerning the effectiveness and feasibility of different variations of the pressure immobilization technique are needed.

Pharmacological approaches that slow lymphatic flow as a snakebite first aid

Background

This study examines the use of topical pharmacological agents as a snakebite first aid where slowing venom reaching the circulation prevents systemic toxicity. It is based on the fact that toxin molecules in most snake venoms are large molecules and generally first enter and traverse the lymphatic system before accessing the circulation. It follows on from a previous study where it was shown that topical application of a nitric oxide donor slowed lymph flow to a similar extent in humans and rats as well as increased the time to respiratory arrest for subcutaneous injection of an elapid venom (Pseudonaja textilis, Ptx; Eastern brown snake) into the hind feet of anaesthetized rats.

Methodology/Principal Findings

The effects of topical application of the L-type Ca²⁺ channel antagonist nifedipine and the local anesthetic lignocaine in inhibiting lymph flow and protecting against envenomation was examined in an anaesthetized rat model. The agents significantly increased dye-measured lymph transit times by 500% and 390% compared to controls and increased the time to respiratory arrest to foot injection of a lethal dose of Ptx venom by 60% and 40% respectively. The study also examined the effect of Ptx venom dose over the lethal range of 0.4 to 1.5 mg/kg finding a negative linear relationship between increase in venom dose and time to respiratory arrest.

Conclusions/Significance

The findings suggest that a range of agents that inhibit lymphatic flow could potentially be used as an adjunct treatment to pressure bandaging with immobilization (PBI) in snakebite first aid. This is important given that PBI (a snakebite first aid recommended by the Australian National Health and Medical research Council) is often incorrectly applied. The use of a local anesthetic would have the added advantage of reducing pain.

Snakebite remains a major problem worldwide causing death or serious illness in many tens of thousands of victims annually. An approach to reduce the burden of envenoming is to provide optimum first aid procedures. We have previously shown that topical application of a nitric oxide (NO) donor slowed lymph flow to similar extent in humans and rats as well as increased the time to respiratory arrest by ∼50% for subcutaneous injection of eastern brown snake venom into the hind feet of anaesthetized rats. The present study examines the use of several other topical pharmacological agents that aim to slow venom toxins reaching the circulation through the lymphatic system. The study found that the agents examined were similarly effective to that previously found for the NO donor. The fact that one of these is a commonly used topical local anesthetic may be an ideal adjunct first aid, as it provides first aid while reducing pain.

Snakebite in Australia: a practical approach to diagnosis and treatment

Snakebite is a potential medical emergency and must receive high-priority assessment and treatment, even in patients who initially appear well. Patients should be treated in hospitals with onsite laboratory facilities, appropriate antivenom stocks and a clinician capable of treating complications such as anaphylaxis. All patients with suspected snakebite should be admitted to a suitable clinical unit, such as an emergency short-stay unit, for at least 12 hours after the bite. Serial blood testing (activated partial thromboplastin time, international normalised ratio and creatine kinase level) and neurological examinations should be done for all patients. Most snakebites will not result in significant envenoming and do not require antivenom. Antivenom should be administered as soon as there is evidence of envenoming. Evidence of systemic envenoming includes venom-induced consumption coagulopathy, sudden collapse, myotoxicity, neurotoxicity, thrombotic microangiopathy and renal impairment. Venomous snake groups each cause a characteristic clinical syndrome, which can be used in combination with local geographical distribution information to determine the probable snake involved and appropriate antivenom to use. The Snake Venom Detection Kit may assist in regions where the range of possible snakes is too broad to allow the use of monovalent antivenoms. When the snake identification remains unclear, two monovalent antivenoms (eg, brown snake and tiger snake antivenom) that cover possible snakes, or a polyvalent antivenom, can be used. One vial of the relevant antivenom is sufficient to bind all circulating venom. However, recovery may be delayed as many clinical and laboratory effects of venom are not immediately reversible. For expert advice on envenoming, contact the National Poisons Information Centre on 13 11 26.

Effectiveness of rapid transport of victims and community health education on snake bite fatalities in rural Nepal

Snake bite is a major public problem in the rural tropics. In southern Nepal, most deaths caused by neurotoxic envenomation occur in the village or during transport to health centers. The effectiveness of victims' transport by motorcycle volunteers to a specialized treatment center, combined with community health education, was assessed in a non-randomized, single-arm, before-after study conducted in four villages (population = 62,127). The case-fatality rate of snake bite decreased from 10.5% in the pre-intervention period to 0.5% during the intervention (relative risk reduction = 0.949, 95% confidence interval = 0.695-0.999). The snake bite incidence decreased from 502 bites/100,000 population to 315 bites/100,000 population in the four villages (relative risk reduction = 0.373, 95% confidence interval = 0.245-0.48), but it remained constant in other villages. Simple educational messages and promotion of immediate and rapid transport of victims to a treatment center decreased the mortality rate and incidence of snake bite in southeastern Nepal. The impact of similar interventions should be assessed elsewhere.

Commentary: pressure bandaging for North American snake bite? No!

This issue of The Journal of Medical Toxicology includes a position statement regarding the use of pressure immobilization for the pre-hospital treatment of North American Crotalinae envenomation. This commentary discusses the background behind the creation of the position statement and explores the issues involved in applying science to real-world public health recommendations and practice.

Pressure bandaging for North American snake bite? No!

This issue of Clinical Toxicology includes a Position Statement regarding the use of pressure immobilization for the pre-hospital treatment of North American Crotalinae envenomation. This Commentary discusses the background behind the creation of the Position Statement and explores the issues involved in applying science to real world public health recommendations and practice.

A pharmacological approach to first aid treatment for snakebite

Snake venom toxins first transit the lymphatic system before entering the bloodstream. Ointment containing a nitric oxide donor, which impedes the intrinsic lymphatic pump, prolonged lymph transit time in rats and humans and also increased rat survival time after injection of venom. This pharmacological approach should give snakebite victims more time to obtain medical care and antivenom treatment.

Snake bite in South Asia: a review

Snake bite is one of the most neglected public health issues in poor rural communities living in the tropics. Because of serious misreporting, the true worldwide burden of snake bite is not known. South Asia is the world's most heavily affected region, due to its high population density, widespread agricultural activities, numerous venomous snake species and lack of functional snake bite control programs. Despite increasing knowledge of snake venoms' composition and mode of action, good understanding of clinical features of envenoming and sufficient production of antivenom by Indian manufacturers, snake bite management remains unsatisfactory in this region. Field diagnostic tests for snake species identification do not exist and treatment mainly relies on the administration of antivenoms that do not cover all of the important venomous snakes of the region. Care-givers need better training and supervision, and national guidelines should be fed by evidence-based data generated by well-designed research studies. Poorly informed rural populations often apply inappropriate first-aid measures and vital time is lost before the victim is transported to a treatment centre, where cost of treatment can constitute an additional hurdle. The deficiency of snake bite management in South Asia is multi-causal and requires joint collaborative efforts from researchers, antivenom manufacturers, policy makers, public health authorities and international funders.

Snake bite

Snake bite is a common and frequently devastating environmental and occupational disease, especially in rural areas of tropical developing countries. Its public health importance has been largely ignored by medical science. Snake venoms are rich in protein and peptide toxins that have specificity for a wide range of tissue receptors, making them clinically challenging and scientifically fascinating, especially for drug design. Although the full burden of human suffering attributable to snake bite remains obscure, hundreds of thousands of people are known to be envenomed and tens of thousands are killed or maimed by snakes every year. Preventive efforts should be aimed towards education of affected communities to use proper footwear and to reduce the risk of contact with snakes to a minimum through understanding of snakes' behaviour. To treat envenoming, the production and clinical use of antivenom must be improved. Increased collaboration between clinicians, epidemiologists, and laboratory toxinologists should enhance the understanding and treatment of envenoming.