Copperhead snakebites: clinical severity of local effects

Clinical Risk Factors Associated with Poor Outcomes in Snake Envenoming: A Narrative Review

Snakebite-related fatalities disproportionately affect populations in impoverished socio-economic regions, marked by limited access to adequate healthcare and constrained antivenom availability. Early medical intervention is pivotal in mitigating mortality and morbidity associated with snakebite envenoming (SBE). While clinical assessment remains fundamental in treating SBE, this review aims to spotlight objective parameters that could also affect outcomes. Selected studies that identify factors associated with poor outcomes are predominantly region-specific, single-site, and observational, yet collectively reveal similar findings. They consistently report factors such as treatment delays, susceptibility in vulnerable groups such as children and pregnant women, as well as various biochemical and haematological abnormalities. Acute kidney injury (AKI), low platelets, leucocytosis, abnormal coagulation, and elevated creatine kinase (CK) all show an association with poor outcomes. Furthermore, recognising rare and unusual SBE presentations such as adrenal insufficiency, severe hypertension, intracranial haemorrhage, acute angle closure glaucoma, and bowel ischaemia also has a bearing on outcomes. Despite the integration of these parameters into clinical decision tools and guidelines, the validation of this evidence is limited. This review underscores the imperative for high-quality, multi-centre studies aligned with consensus-driven Core Outcome Sets (COS) and Patient-Reported Outcome Measures (PROMS) to validate and strengthen the current evidence.

Evaluation of the properties of Bungarus caeruleus venom and checking the efficacy of antivenom used in Bangladesh for its bite treatment

As a disaster-prone country with unique geographical features, snake biting is a major public health concern in Bangladesh. The primary reasons of mortality from snakebite include late presentation to the hospital, low efficacy of antivenom, and a lack of adequate management facilities. Because snake venom characteristics vary depending on geographical location, antivenom should be manufactured from snakes native to the region in which it would be administered. Bungarus caeruleus is a highly venomous snake contributing to the major snakebite issue in Bangladesh. Therefore, the neutralization efficacy of the antivenom against B. caeruleus venom was evaluated in the current study along with the characterization of venom. For biological characterization of venom, RP-HPLC and SDS-PAGE profiling, hemolytic activity, hemorrhagic activity, phospholipases A₂ (PLA₂) activity, edema inducing activity and histopathological observations were carried out following standard protocol. LD₅₀ of the venom was calculated along with neutralization potency of Incepta antivenom through probit analysis. Results showed that venom possesses phospholipase A₂ activity, hemolytic activity and edema inducing activity while hemorrhagic activity was absent in the skin of envenomed mice. Histopathological alterations including necrosis, congestion and infiltrations were observed in envenomed mice organs after hematoxylin and eosin staining. Neutralization study showed that Incepta polyvalent antivenom could neutralize (potency 0.53 mg/ml) the lethal effect in in vitro study on mice. Further investigation on snakebite epidemiology and clinical observations of the envenomed patients will help in combating the snakebite problem more efficiently.

A Viper bite in an urban area : A case report

Envenomous viper snakes are not natural inhabitants of Istanbul, Turkey. The city is crowded and lacks an appropriate area for wild life. Viper snakes are mostly found in southern and middle rural Anatolia in Turkey. To our knowledge, viper bites have not been reported in our urban area previously. Here, we report a envenomous snakebite case, treated with polyvalent antivenom successfully. The snake was identified as Vipera Pontica, by the National Poisons Center.

Predictors of FabAV use in copperhead envenomation

CONTEXT

Crotaline snake envenomation is a serious medical condition affecting thousands of Americans each year. Variation in the treatment of Crotaline snakebites exists among physicians in the United States. Management of copperhead snakebites is controversial with some experts advocating minimal intervention, rarely necessitating antivenom use and, even more rarely, surgical intervention. This study assessed the use of Crotaline Polyvalent Immune Fab antivenom (Ovine) (FabAV) and explored factors influencing the decision to prescribe antivenom for copperhead envenomation in patients in Northeastern Oklahoma.

METHODS

A retrospective cohort study examining electronic medical records of patients with copperhead snakebites from July 1, 2014 to August 31, 2019. Data collected included: patient demographics, transfer information, snake species, bite site, progression of local tissue effects, additional clinical and lab results, patient comorbidities, and treatment strategy. Associations between patient variables and treatment were evaluated using the chi-square test of independence, median test, and logistic regression analysis. Associations were statistically significant if p < 0.05.

DISCUSSION

Of the 130 patients bitten by a copperhead, a majority (75%) received FabAV. Symptoms of copperhead envenomation were mostly limited to the progression of tissue damage. Predictors of treatment with FabAV included progression of venom effects across major joints, younger age, comorbidities, and upper extremity bites.

CONCLUSIONS

Patients who have multiple comorbidities, upper extremity bites and progression of venom effects across major joints are more likely to be treated with FabAV. The high usage of FabAV at the study site underscores the need for continued work to optimize the use of antivenom for copperhead envenomations.

Retrospective Analysis of the Demographic and Clinical Features of Snake Bites Followed in the Intensive Care Unit

Objective Cases of poisoning due to snake bite are a medical condition that requires an emergency treatment approach, which creates serious health problems that can be seen in our country and all over the world. In the Eastern Anatolia Region, poisoning cases due to the bites of viper snakes, especially from the Viperidae family, are frequently seen. The aim of this study is to examine the bite sites, clinical stages, antivenom needs and doses, changes in blood biochemistry, prognostic characteristics of patients treated in our intensive care unit for snake bites in our region, and to present our regional experience with snake bites. Material and Methods Our study included 44 patients who were treated in the intensive care clinic with the complaint of snake bite between August 1, 2018 and August 1, 2021. Symptoms, bite sites, clinical stages, need and doses of antivenom, length of hospital stay, changes in blood biochemistry and mortality of these patients who were exposed to snake bites were retrospectively investigated. Results A total of 44 patients, 13 female (29.55%) and 31 male (70.45%), aged between 18-72 years, who were followed up due to snake bites, were included in the study. In our study, 1 (2.27%) patients in Stage 0, 18 (40.90%) in Stage 1, 21 (47.7%) in Stage 2 and 4 (9.09%) patients in Stage 3 it was found that he was followed up due to snake bite. While total antivenom (4.33±2.18) vials were given to 10 intoxication cases with stage (0-1), vials of total antivenom were given to 25 (7.65±3.03) intoxication cases with stage (2-3). Conclusion We believe that in addition to antivenom treatment in sufficient doses and in an early time, the first correct intervention to snake bite can prevent problems that may develop after poisoning.

No Change in the Use of Antivenom in Copperhead Snakebites in Ohio

INTRODUCTION

Historically, copperhead snake (Agkistrodon contortrix) envenomations were not treated with antivenom owing to related adverse events and little benefit. However, recent studies have shown improved outcomes with antivenom use. We hypothesized that the frequency of antivenom use for copperhead envenomation in Ohio has increased as benefits of administration became more widely known.

METHODS

All copperhead snakebites reported to the Ohio poison control centers from 2006 through 2016 were compiled. Antivenom use, bite severity, and disposition were abstracted. A nonparametric test for trend was used to evaluate changes over time for the number of patients treated with antivenom and patient disposition. Logistic regression was used to assess the odds of admission vs discharge with antivenom administration, bite severity, age, and sex as independent variables.

RESULTS

Ninety-eight patients reported copperhead snakebites to the poison control centers. The test of trend showed no change in the proportion of patients treated with antivenom by year (P=0.42). There was no difference in the proportion of patients discharged home (P=0.38) per year. Logistic regression showed antivenom use was associated with an odds ratio for admission of 46.7 (95% CI: 7.3-296.4).

CONCLUSIONS

The frequency of antivenom use for copperhead bites did not significantly increase between 2006 and 2016. Administration of antivenom was associated with a large increase in the odds of admission to the hospital, even when controlling for bite severity. Further education regarding the benefits and safety of antivenom may increase its use for copperhead snakebites, but may lead to an increase in hospital admissions.

Negative pressure wound therapy for skin necrosis prevention after snakebite in the emergency department: A retrospective cohort study

This retrospective cohort study aimed to compare the effectiveness of conventional treatment and ultra-early application of negative pressure wound therapy (NPWT) in patients with snakebites.Patients who visited the emergency department within 24 hours after a snakebite were assigned to the non- NPWT or NPWT group. Swelling resolution time and rates of necrosis, infection, and operations were compared between the 2 groups. The Stony Brook Scar Evaluation Scale was used to measure short- and long-term wound healing results.Among the included 61 patients, the swelling resolution time was significantly shorter in the NPWT group than in non- NPWT group (P = .010). The NPWT group showed lower necrosis (4.3% versus 36.8%; P = .003) and infection (13.2% and 4.3%; P = .258) rates than the non- NPWT group. The median Stony Brook Scar Evaluation Scale scores were higher in the NPWT group than in the non- NPWT group (P< .001).These findings suggest that ultra-early application of NPWT reduces edema, promotes wound healing, and prevents necrosis in patients with snakebites.

Delayed Splenic Rupture: A Rare Complication of Snakebites

Bites by venomous snakes can cause fatal systemic and coagulation disorders. Rare complications, such as compartment syndrome and hemoperitoneum, may also require surgical intervention. Here, we describe our experience with an unusual case of snakebite-induced delayed splenic rupture. A 54-y-old male with no specific medical history visited a local hospital for a bite by an unidentified snake. He had been bitten on the left thumb and was administered antivenom. He was discharged from the local hospital after 3 d when his symptoms had improved. However, he revisited our emergency medical center 2 d later, reporting dizziness with diaphoresis. Focused abdominal ultrasonography and computed tomography revealed large amounts of intraperitoneal fluid collection and hemoperitoneum with splenic rupture, respectively. The patient underwent immediate blood transfusion and received antivenom treatment in our emergency department and, subsequently, emergency splenectomy. Histopathologic findings at the time of surgery revealed multifocal lacerations on the external surface of the spleen, with fresh hemorrhage. He recovered 7 d after surgery without any complication.

Comparison of venom from wild and long-term captive Gloydius caucasicus and the neutralization capacity of antivenom produced in rabbits immunized with captive venom

Gloydius caucasicus (NIKOLSKY, 1916) is a member of the Viperidae family in Iran. Comprehensive understanding of the toxigenic characteristics of snake venom is important for clinical monitoring of snakebite patients and effective therapy. We compared the toxic activities of venoms and the neutralization capacity of antivenoms produced with venoms from wild adult (WA) with long-term captive adult (LCA) of G. caucasicus in order to obtain more effective antivenom from LCA in therapy, and subsequently protect G. caucasicus from overharvesting for its venom, which poses a real threat of extinction for the species. Our results showed that LD50 of WA and LCA were 16.8 μg/dose and 17.7 μg/dose, respectively. Lower hemorrhagic and necrotic (p ≥ 0.05), and higher coagulative and edematogenic activities (p ≤ 0.05) were observed in WA compared with LCA venom. Also, captive-born neonates exhibited weaker toxic activities compared with captive adult snakes, which could be an age-related difference. Study data illustrated that effective capacity of LCA antivenom to neutralize the toxic activities of WA viper venom. According to the results, about 0.4-4 μl of LCA antivenom is required to neutralize the toxic activities of 1 μg of WA venom, indicating its efficacy in treatment of snakebites in humans. On this basis, it is recommended that capture of wild snakes for their venom be discontinued to reduce their future extinction risk.

Does This Patient Have a Severe Snake Envenomation?: The Rational Clinical Examination Systematic Review

Importance

Venomous snakebite severity ranges from an asymptomatic dry bite to severe envenomation and death. The clinical evaluation aids in prognosis and is essential to determine the risks and potential benefits of antivenom treatment.

Objectives

To identify historical features, clinical examination findings, basic laboratory testing, and clinical grading scales that will risk-stratify patients with pit viper snake envenomation for severe systemic envenomation, severe tissue injury, and/or severe hematologic venom effects.

Data Sources

We conducted a structured search of PubMed (1966-October 3, 2017) and Embase database (1980-October 3, 2017) to identify English-language studies that evaluated clinical features predictive of severe envenomation.

Study Selection

We included studies that evaluated the test performance of at least 1 clinical finding with an acceptable reference standard of severe envenomation for venomous snakes of the Western Hemisphere. Only studies involving the most common subfamily, Crotalinae (pit vipers), were evaluated. Seventeen studies with data were available for abstraction.

Data Extraction and Synthesis

The clinical features assessed and severity outcome measures were extracted from each original study. We assessed severity in 3 categories: systemic toxicity, tissue injury, and hematologic effects. Differences were resolved by author consensus.

Results

The pooled prevalence of severe systemic envenomation was 14% (95% CI, 9%-21%). The pooled prevalence of severe tissue injury and severe hematologic venom effects were 14% (95% CI, 12%-16%) and 18% (95% CI, 8%-27%), respectively. Factors increasing the likelihood of severe systemic envenomation included the time from bite to care of 6 or more hours (likelihood ratio [LR], 3.4 [95% CI, 1.1-6.4]), a patient younger than 12 years (LRs, 3.2 [95% CI, 1.5-7.1] and 2.9 [95% CI, 1.3-6.2]), large snake size (LR, 3.1 [95% CI, 1.5-5.7]), and ptosis (LRs, 1.4 [95% CI, 1.0-2.1] and 3.8 [95% CI, 1.8-8.3]). Envenomation by the genus Agkistrodon (copperhead and cottonmouth), as opposed to rattlesnakes, decreased the likelihood of severe systemic envenomation (LR, 0.28 [95% CI, 0.10-0.78]). Initial hypofibrinogenemia (LR, 5.1 [95% CI, 1.7-15.0]) and thrombocytopenia (LR, 3.7 [95% CI, 1.9-7.3]) increased the likelihood of severe hematologic venom effects. Other clinical features from history, physical examination, or normal laboratory values were not discriminative.

Conclusions

Clinical features can identify patients at increased risk of severe systemic envenomation and severe hematologic venom effects, but there are few features that are associated with severe tissue injury or can confidently exclude severe envenomation. Physicians should monitor patients closely and be wary of progression from nonsevere to a severe envenomation and have a low threshold to escalate therapy as needed.

Biochemical and immunochemical characterization of venoms from snakes of the genus Agkistrodon

In the present work, venoms from five species of the genus Agkistrodon were evaluated in terms of their enzymatic (Phospholipase A2 and caseinolytic) and biological (edema forming, hemorrhagic, procoagulant and lethal) effects. Horses were used to produce monovalent hyperimmune sera against each of three venoms (A. bilineatus, A. contortrix and A. piscivorus) and their neutralizing potency, expressed as Median Effective Dose (ED50), was determined against the venoms of all five species. In terms of PLA2 and caseinolytic activities, all venoms are extremely homogeneous. PLA2 activity is high, while caseinolytic activity is low when in contrast with that of the rattlesnake Crotalus simus. On the other hand, biological activities showed marked interspecific differences, particularly between the species from Mexico and those from the United States. Mexican species displayed higher edema-forming, hemorrhagic and lethal effects than US species, while none of the species studied presented procoagulant activity. All three monovalent hyperimmune sera showed good neutralizing potency against the analyzed venoms. Nonetheless, we observed relevant immunochemical differences among the venoms using ELISA and Western Blot assays. We conclude that the venoms of A. piscivorus (USA) and A. bilineatus would be ideal to use as immunogens for the production of a polyvalent antivenom with good neutralizing potency against the venoms of all the species of the genus.

Effectiveness of repeated antivenom therapy for snakebite-related systemic complications

Objective

This study aimed to determine the effect of repeated antivenom therapy compared with that of single antivenom therapy for treating snakebite-related systemic complications.

Methods

A retrospective medical record review from January 2008 to September 2016 was performed. Patients with snakebite injury who visited the Emergency Department in one tertiary center of Korea were included. The primary outcome was the survival rate. The secondary outcome was the effect of repeated antivenom therapy for treating snakebite-related systemic complications compared with that of single antivenom therapy on hospital length of stay.

Results

A total of 110 patients with snakebites were included. All patients survived to discharge. Twenty-nine (26.4%) patients had snakebite-related systemic complications. Of these, nine patients received repeated antivenom therapy and 20 patients received single antivenom therapy. The length of stay was significantly longer in those who received repeated antivenom therapy compared with those who received single antivenom therapy (10.0 [4.0–11.0] vs. 3.5 [0–7.0] days).

Conclusion

We were unable to demonstrate any superiority of repeated versus single antivenom therapy. However, repeated antivenom therapy is associated with a longer hospital stay. The reason for this finding is unknown.

Misidentification of copperhead and cottonmouth snakes following snakebites

INTRODUCTION

Copperhead (Agkistrodon contortrix) and cottonmouth or water moccasin (Agkistrodon piscivorus) snakes account for the majority of venomous snakebites in the southern United States. Cottonmouth snakes are generally considered to have more potent venom. Copperheads are considered less venomous and there is some controversy as to whether or not bites from copperhead snakes need to be treated with antivenom. Copperhead and juvenile cottonmouth snakes are both brown in color. The purpose of this study was to evaluate the accuracy of identification by the public and healthcare providers between these two species.

METHODS

Snakebite victims sometimes bring dead snakes to the hospital or have taken pictures of the snake. When this occurred, ED personnel were asked to take a picture of the snake, and forward the picture to the state poison control center. The identification of the snake by witnesses and/or hospital personnel was compared to the identification by the state herpetologist.

RESULTS

During the study period, there were 286 cases of snakebites reported to the state poison control center. Pictures were obtained on 49 of the responsible snakes. All copperhead snakes were identified correctly by callers. However, only 21% of cottonmouth snakes were identified correctly, with 74% of cottonmouth snakes being identified as copperheads. Both public and medical personnel performed poorly on identification of cottonmouth snakes.

CONCLUSIONS

Forty percent of the snakes identified as copperheads were actually cottonmouth snakes. Juvenile cottonmouth snakes were often identified as copperhead snakes.

Administration of CroFab Antivenom by a Helicopter Emergency Medical Service Team

The case presented here highlights an unconventional use of a helicopter emergency medical service (HEMS) to provide a specialized medication to a critically ill patient when definitive transport was delayed. A 39-year-old man presented to a rural hospital 1 hour after sustaining a copperhead envenomation. He developed severe symptoms and was intubated. Arrangements were made for transfer to a tertiary referral center by HEMS, but because of incoming weather conditions, the team would not be able to make the return flight safely. The decision was made for the HEMS team to fly antivenom to the patient, administer the medication, and then transport the patient by ground to the tertiary medical center. This plan was executed, and the patient was safely transported to the accepting facility. Antivenom is most effective when administered early because this will halt the progression of edema and may reverse the systemic effects of envenomation. In this case, HEMS transport of antivenom to the patient with severe toxicity prevented a delay to administration and likely improved the patient's outcome. Although the traditional role of HEMS is to provide rapid transport to critically ill patients, HEMS teams can also function to deliver specialized medications to remote settings.

An Analysis of Media-Reported Venomous Snakebites in the United States, 2011-2013

BACKGROUND

Venomous snakebite is a widespread natural hazard in the United States. A common perception exists that the majority of these snakebites are "illegitimate," resulting from deliberate interaction with snakes (such as attempting to move or kill the animal), but there is little quantitative information available regarding the conditions under which bites occur.

METHODS

To better understand the circumstances under which victims are bitten, we compiled a dataset of media-reported snakebites in the United States between 2011 and 2013. A total of 332 reported snakebites were recorded. Of these, 307 were from snakes encountered under natural circumstances and 25 were under captive-care conditions.

RESULTS

Most reported victims were adult males. Although some bites occurred during intentional handling of snakes and such activity may relate to bite severity, the majority of victims reported being unaware of the snake before they were bitten. Accidentally stepping on or placing the hands near an unseen snake were the activities most frequently associated with bites under natural conditions.

CONCLUSIONS

Although bias in snakebite reporting patterns by the media is likely, across the United States "legitimate" bites from unseen snakes appear to be the norm.

Does the traditional snakebite severity score correctly classify envenomated patients?

OBJECTIVE

This study aims to help set domestic guidelines for administration of antivenom to envenomated patients after snakebites.

METHODS

This retrospective observational case series comprised 128 patients with snake envenomation. The patients were divided into two groups according to the need for additional antivenom after the initial treatment based on the traditional snakebite severity grading scale. One group successfully recovered after the initial treatment and did not need any additional antivenom (n=85) and the other needed an additional administration of antivenom (n=43).

RESULTS

The group requiring additional administration of antivenom showed a higher local effect score and a traditional snakebite severity grade at presentation, a shorter prothrombin and activated partial prothrombin time, a higher frequency of rhabdomyolysis and disseminated intravascular coagulopathy, and longer hospitalization than the group that did not need additional antivenom. The most common cause for additional administration was the progression of local symptoms. The independent factor that was associated with the need for additional antivenom was the local effect pain score (odds ratio, 2.477; 95% confidence interval, 1.309 to 4.689). The optimal cut-off value of the local effect pain score was 1.5 with 62.8% sensitivity and 71.8% specificity.

CONCLUSION

When treating patients who are envenomated by a snake, and when using the traditional snakebite severity scale, the local effect pain score should be taken into account. If the score is more than 2, additional antivenom should be considered and the patient should be frequently assessed.

A Multidisciplinary Approach with Hyperbaric Oxygen Therapy Improve Outcome in Snake Bite Injuries

Aim:

Snakebite injuries are common in tropical India among those who are involved in outdoor activities. These injuries results in cellulitis, gangrene at the bite area, bleeding manifestations, compartment syndrome, regional lymphadenopathy, septicemia, hypotension, and disseminated intravascular coagulation (DIC) resulting in significant morbidity and mortality. The purpose of this study is to share our experience of multidisciplinary approach in the management of snakebite injuries of the extremities with various treatment modalities including hyperbaric oxygen (HBO) therapy, surgical debridement, and soft tissue reconstruction to provide an effective treatment for snake bite injuries.

Methods:

The study was conducted in the Department of Plastic Surgery, during the period October 2012–December 2014, wherein all the patients who were admitted with snakebite injuries were enrolled and the patients treated in plastic surgery department were included into the study. Out of total 766 patients, there were 323 patients treated with anti snake venom (ASV) and 29 died among the treated patients; 205 patients belonged to pediatric age group.

Results:

Out of 112 patients referred to Department of Plastic Surgery, 50 cases presented with cellulitis, 24 patients with compartment syndrome, and 38 patients were referred for the management of soft tissue cover over the extremities. Among 112 patients, 77 involved the lower extremity and 35 the upper extremity.

Conclusion:

Multidisciplinary approach including hyperbaric oxygen (HBO) therapy improves outcome in the management of snakebite injuries of the extremities.

FabAV antivenin use after copperhead snakebite: clinically indicated or knee-jerk reaction?

Background

Crotalidae Polyvalent Immune Fab (Ovine) (FabAV) antivenin is commonly recommended after pit viper snakebites. Because copperhead envenomations are usually self-limited, some physicians are reluctant to use this costly treatment routinely, while others follow a more liberal approach. We hypothesized that, in practice, only patients with evidence of significant (moderate or severe) copperhead envenomation [those with snakebite severity score (SSS) > 3] receive FabAV and examined a large cohort to determine the relationship between clinical findings and FabAV administration.

Methods

All data from patients evaluated for copperhead snakebite at a rural tertiary referral center from 5/2002 to 10/2013 were compiled. Demographics, transfer status, antivenin use, and clinical findings were collected; SSS was calculated. The relationships among FabAV use, clinical findings, and SSS were analyzed using t-test, chi-square, and Pearson’s coefficient (p < 0.05 was significant).

Results

During the study period, 318 patients were treated for copperhead snakebite; 44 (13.8 %) received antivenin. Median dose was four vials (range: 1–10; IQR: 4,6). There were no deaths. Most patients receiving FabAV (63.6 %) were admitted. With regard to demographics and symptoms, only the degree of swelling (moderate vs. none/mild; p < 0.01) and bite location (hand/arm vs. leg: p < 0.0001) were associated with FabAV use. A SSS > 3, indicating moderate or severe envenomation, was only very weakly correlated with antivenin use (r = 0.217; p < 0.0001). The majority of patients with SSS > 3 (65.8 %) did not receive antivenin while most patients who did receive antivenin (70.5 %) had SSS ≤ 3 (indicating mild envenomation).

Conclusions

Considerable variation occurs in antivenin administration after copperhead snakebite. Use of FabAV appears poorly correlated with patients’ symptoms. This practice may expose patients to the risks of antivenin and increasing costs of medical care without improving outcomes. Guidelines used for treating other pit viper strikes, such as rattlesnake or cottonmouth snakebite may be too liberal for copperhead envenomations. Our data suggests that most patients with mild or moderate envenomation appear to do well independent of FabAV use. We suggest, for patients with copperhead snakebite, that consideration be given to withholding FabAV for those without clinical evidence of severe envenomation until prospective randomized data are available.

Presumptive intraperitoneal envenomation resulting in hemoperitoneum and acute abdominal pain in a dog

OBJECTIVE

To describe the clinical features, diagnostic findings, treatment, and outcome of a dog with acute abdominal pain and hemoperitoneum secondary to a presumptive intraperitoneal (IP) snakebite.

CASE SUMMARY

A 10-month-old castrated male mixed-breed dog was evaluated for suspected snake envenomation. The dog presented recumbent and tachycardic with signs of severe abdominal pain. Two cutaneous puncture wounds and hemoperitoneum were discovered during evaluation. Ultrasonographic examination revealed communication of the wounds with the peritoneal cavity. The dog was treated with supportive care, parenteral analgesia, packed red blood cell and fresh frozen plasma transfusions, crotalid antivenom, and placement of an IP catheter to provide local analgesia. The dog recovered fully and was discharged 5 days after initial presentation.

NEW OR UNIQUE INFORMATION PROVIDED

To our knowledge, this is the first report of IP envenomation accompanied by hemorrhage treated with continuous IP analgesia in the veterinary literature.

Rebound coagulopathy in patients with snakebite presenting with marked initial coagulopathy

OBJECTIVE

An estimated 70% of patients with pit viper snakebites require antivenom to treat serious complications such as coagulopathy. Evidence-based guidance is limited for the appropriate administration of Crotalinae Polyvalent Immune Fab (FabAV) and the duration of laboratory follow-up. The objective of our study was to assess the incidence of marked and recurrent envenomation coagulopathy at our trauma center and identify practice patterns that may prevent serious complications.

METHODS

A retrospective case review was conducted over a 3-year period on patients treated for symptomatic snakebite injury. Case records were reviewed for the inclusion criteria of international normalized ratio (INR) greater than 2.0. The exclusion criterion was limited to patients receiving anticoagulant therapy.

RESULTS

In all, 61 patients were identified on retrospective chart review and 3 patients (4.9%) met inclusion criteria. Two of the 3 patients had marked rebound coagulopathy requiring readmission and additional treatment. In our small series, 2 patients presenting after crotaline envenomation with increased INR (>6.0), decreased fibrinogen (<60 mg/dL), and decreased platelet count (<100,000/mL) had recurrent coagulopathy and were asymptomatic, and recurrence was noted only with follow-up laboratory testing. All patients responded positively within a matter of hours to repeat FabAV administration, with resolution of rebound coagulopathy.

CONCLUSIONS

We recommend periodic monitoring of patients with increased INR, decreased fibrinogen, and decreased platelet count. Patients should be monitored for 10 to 14 days after envenomation to identify asymptomatic rebound coagulopathy. Prompt readministration of FabAV appears to correct the coagulopathy.

Time to antivenom administration is not associated with total antivenom dose administered in a copperhead-predominant snakebite population

OBJECTIVES

To prevent unnecessary antivenom administration in crotaline snakebite, observation for progression is recommended for the patient with minor envenomation whose condition is stable and not progressing. The objective of this study was to determine the association between the time from bite to initial antivenom administration (Time(AV)) and the total amount of antivenom administered (Total(AV)) and to determine what proportion of patients did not have progression of the envenomation syndrome and did not receive antivenom.

METHODS

This was a retrospective chart review of patients presenting with crotaline snakebite within 24 hours from 2009 through 2012. Blinded dual-chart abstraction and strict data point definitions were used. Spearman correlation was used to determine the association between Time(AV) and Total(AV). A general linear model was used to examine this association using Time(AV) categorized to early and late administration, adjusted for likely confounders. Confounders included age, extremity involved, initial severity, and year of envenomation.

RESULTS

Ninety-five eligible patients were analyzed with 45 (47%) males and a mean (±SD) age of 36.5 (±21.1) years. Eighty-five (89%) received antivenom, with a median Time(AV) of 3.3 hours (interquartile range [IQR] = 2.5 to 5.2 hours). The median Total(AV) was 10 vials (IQR = 6 to 14 vials). The univariate analysis showed a small but statistically significant decrease in Total(AV) given to patients treated greater than 6 hours from bite (r = -0.26, p = 0.015). The multivariate analysis resulted in no significant relation between early or late Time(AV) and Total(AV) (p = 0.10) after adjustment for confounders. Most minimal envenomation syndromes (80%, or 41 of 51) progressed to moderate grade envenomations.

CONCLUSIONS

Time(AV) was not associated with Total(AV) when adjusted for likely confounders and supports current recommendations to observe for progression in minor envenomation. The majority of envenomations progressed, resulting in only a small proportion of patients not eventually receiving antivenom. The authors recommend observation in an environment where the patient can be adequately reassessed for progression of the envenomation.

Unified treatment algorithm for the management of crotaline snakebite in the United States: results of an evidence-informed consensus workshop

BACKGROUND

Envenomation by crotaline snakes (rattlesnake, cottonmouth, copperhead) is a complex, potentially lethal condition affecting thousands of people in the United States each year. Treatment of crotaline envenomation is not standardized, and significant variation in practice exists.

METHODS

A geographically diverse panel of experts was convened for the purpose of deriving an evidence-informed unified treatment algorithm. Research staff analyzed the extant medical literature and performed targeted analyses of existing databases to inform specific clinical decisions. A trained external facilitator used modified Delphi and structured consensus methodology to achieve consensus on the final treatment algorithm.

RESULTS

A unified treatment algorithm was produced and endorsed by all nine expert panel members. This algorithm provides guidance about clinical and laboratory observations, indications for and dosing of antivenom, adjunctive therapies, post-stabilization care, and management of complications from envenomation and therapy.

CONCLUSIONS

Clinical manifestations and ideal treatment of crotaline snakebite differ greatly, and can result in severe complications. Using a modified Delphi method, we provide evidence-informed treatment guidelines in an attempt to reduce variation in care and possibly improve clinical outcomes.

[Epidemiology of envenomation by snakebite in pediatric intensive care unit at Children's hospital of Rabat, Morocco]

The snakebite is the most severe form of envenomation. The aim of this retrospective study was to describe the epidemiological, diagnostic, therapeutic and evolutionary snakebites in Children in paediatric intensive care unit of the children's hospital of Rabat. The criteria of severity were studied in four grades : grade 0 (traces of hooks at the bite, no swelling or local reaction), grade 1 (local oedema, absence of constitutional symptoms), grade 2 (swelling of regional member and/or moderate symptoms), grade 3 (extensive swelling up the trunk and/or severe symptoms). The number of patients included was 17 between January 2004 and December 2009. The male predominance (59%), bites by snakes (76%), bites during the afternoons (76%) and summer (53%), bites to the lower limb (65%) were net, corroborating the data from the literature on the subject. The median period of treatment was 9.5 hours, 53% of cases of severe grade 2 and 3 versus 47% in grades 0 and 1. The median duration of hospitalization was five days. One child died (6%). No child received antivenin treatment. Our analysis calls for the availability of specific immunotherapy in local health institutions in high-risk areas, such as ours.

Evidence-Based, Multidisciplinary Approach to the Development of a Crotalidae Polyvalent Antivenin (CroFab) Protocol at a University Hospital

Background:

Several thousand people are bitten annually by venomous snakes in the US. While the development of ovine Crotalidae polyvalent immune Fab antivenin (FabAV) for Crotalinae snakebite envenomations has greatly changed the way this clinical presentation is treated, multiple issues complicate its use. From patient assessment and evaluation, to medication preparation and administration, to the management of adverse drug reactions, the use of this antidote carries with it multiple points of possible medication variances. The inappropriate use of this agent can result in adverse patient consequences and a significant financial burden for both the hospital and the patient.

Objective:

To describe an evidence-based, multidisciplinary approach that was taken to ensure optimal, safe, and cost-effective treatment of patients with FabAV.

Methods:

Following an analysis of the available literature, a multidisciplinary committee was formed to construct a protocol for use of FabAV. This group included clinical pharmacists, pharmacy administrators, emergency medicine physicians who specialized in wilderness medicine and pharmacy residents.

Results:

A multidisciplinary FabAV usage protocol was constructed and implemented to ensure appropriate patient evaluation, FabAV use and preparation, monitoring, and follow-up. This protocol was based on the available literature and the expert opinion of the committee. Through the use of a 24-hour in-house pharmacy resident on-call system, clinical pharmacy services were provided to ensure a multidisciplinary approach to the care of these patients emergently. Although limited, initial data show that this approach is effective and may result in substantial cost savings.

Conclusions:

Initial results from implementation of a protocol for use of FabAV have limited inappropriate use, reduced medication wastage, and decreased costs.

Crotalidae polyvalent immune Fab for the treatment of pediatric crotaline envenomation

Crotaline snakebites occur frequently in children, often resulting in significant morbidity. Crotalidae Polyvalent Immune Fab antivenom (FabAV) became available for clinical use in the US in 2000 and is currently the standard of care for the treatment of crotaline envenomation. The pediatric emergency care provider should be familiar with FabAV because its judicious use in affected children can greatly decrease morbidity caused by crotaline snakebites. This article will review the use of FabAV for the treatment of pediatric crotaline envenomation.

Use of CroFab® antivenin in the management of a very young pediatric copperhead envenomation

The use of crotalid Fab antivenin (CroFab) in the treatment of snake envenomations in the pediatric population is still an underexplored area. There are very limited data to confirm the efficacy and safety of dosing children the same as adults and even less information available to evaluate this antivenin use in copperhead snake bites in children. We report the first use of crotalid Fab antivenin in an adult dose for a copperhead snake envenomation in a 2-year-old child. She had rapid resolution of symptoms with no adverse effects. The report serves to increase the literature supporting the current dosing recommendations of crotalid Fab antivenin in very young pediatric patients evidenced by its effectiveness in this patient.

Initial experience with Crotalidae polyvalent immune Fab (ovine) antivenom in the treatment of copperhead snakebite

STUDY OBJECTIVE

Crotalidae polyvalent immune Fab (ovine) (CroFab; FabAV) effectively treats patients bitten by rattlesnakes. The copperhead snake (Agkistrodon contortrix) caused 37% of venomous snakebites reported to US poison centers in 2001 and is the major envenomating reptile in the southeastern United States. FabAV has not been tested in human beings envenomated by copperhead snakes.

METHODS

In this preliminary study, we performed a retrospective chart review of all copperhead snake envenomations reported to the Carolinas Poison Center that were treated with FabAV. Progression of limb swelling, coagulopathy, and hemodynamic status before and after FabAV administration, adverse effects of FabAV therapy, and recurrence phenomena were recorded.

RESULTS

Of approximately 400 copperhead envenomation cases reported to the poison center during the study period, 32 received FabAV and were included. Most patients had moderate envenomation. The median time to FabAV administration was 4.0 hours. The median time to achieve initial control was 1.0 hour, with a median dose of 4 vials of FabAV. A rapid initial response, defined as cessation of the progression of local tissue injury within 4 hours of FabAV administration, occurred in 28 cases (88%; 95% confidence interval [CI] 76% to 99%). Four cases (13%; 95% CI 1% to 24%) were considered treatment failures. Recurrent swelling occurred in 6 cases (19%; 95% CI 5% to 32%). The incidence of recurrent swelling was not reduced by administration of repeated doses of antivenom on a planned schedule. One patient developed late-onset coagulopathy. One minor allergic reaction was observed.

CONCLUSION

In this select group of patients bitten by copperhead snakes, local tissue effects of envenomation halted promptly after FabAV treatment in most cases. Treatment failures occurred, and recurrence of swelling and defibrination syndrome was sometimes problematic. Time to return to work and long-term limb function were not assessed. A controlled trial with long-term follow-up is needed to define the role of FabAV treatment for copperhead envenomation.

Preclinical assessment of the ability of polyvalent (Crotalinae) and anticoral (Elapidae) antivenoms produced in Costa Rica to neutralize the venoms of North American snakes

Polyvalent (Crotalinae) and anticoral (Elapidae) antivenoms produced by Instituto Clodomiro Picado, Costa Rica, were assessed for their ability to neutralize various toxic activities of the venoms of North American snakes of the genera Crotalus, Agkistrodon and Micrurus, in assays involving preincubation of venom and antivenom. When the intraperitoneal route of injection was utilized, polyvalent (Crotalinae) antivenom was effective in the neutralization of the venoms of Crotalus atrox, Crotalus adamanteus, Crotalus viridis viridis, Crotalus horridus atricaudatus, Agkistrodon contortrix contortrix and Agkistrodon piscivorus piscivorus, whereas the venom of Crotalus scutulatus was not neutralized. When the intravenous route was used, results differed depending on the "challenge dose" of venom employed. Polyvalent antivenom neutralized all venoms when mice were challenged with 2 LD(50)s of venom. When 5 LD(50)s were used, antivenom neutralized the venoms of C. atrox, C. adamanteus, C. v. viridis and C. h. atricaudatus, being ineffective in the neutralization of C. scutulatus, A. c. contortrix and A. p. piscivorus. Polyvalent antivenom was effective in the neutralization of hemorrhagic and myotoxic activities of all venoms studied. It also neutralized coagulant activity of C. adamanteus venom, whereas most of the venoms were devoid of clotting activity on plasma in vitro. Moreover, it neutralized defibrinating activity of the only three venoms that induced this effect (i.e. C. adamanteus, A. c. contortrix and A. p. piscivorus). Anticoral (Elapidae) antivenom neutralized lethality induced by the venom of Micrurus fulvius, using either the intravenous or the intraperitoneal routes of injection. Moreover, it neutralized myotoxic effect of this venom as well. It is concluded that polyvalent antivenom neutralizes lethality and other activities of most of the crotaline venoms tested. However, since it is ineffective in neutralizing the lethal effect of C. scutulatus venom, it is suggested that a venom containing presynaptically-active neurotoxic phospholipases A(2) related to "mojave toxin" needs to be introduced in the immunizing mixture in order to increase the neutralizing scope of this product in North America. Anticoral antivenom is highly effective in the neutralization of the venom of M. fulvius.

Prospective study of morbidity associated with snakebite envenomation

BACKGROUND

The morbidity associated with snakebite envenomation has not been well documented.

METHOD

Using a standardized questionnaire all patients with snakebite reported to a regional poison center during the year 2001 were followed after hospital discharge by telephone until resolution of symptoms.

RESULTS

One hundred and twenty-eight snakebite cases were reported, of which 16 (12.5%) were lost to follow-up and 31 (24.2%) reported no progression of symptoms beyond puncture and were deemed "dry bites." Eighty-one (63.3%) patients were followed for the duration of symptoms. Age ranged from 1 to 86 years with a mean of 32 years. There were 64 males (79%). The snakes were identified as copperhead (n = 57), unidentified venomous (n = 17), timber rattlesnake (n = 6), and cottonmouth (n = 1). All patients were initially evaluated in a hospital emergency department of which 51 were admitted. Nine patients received antivenin. Of the 37 patients who had a job, 33 lost a mean of 14 days of work (SD +/- 18.1). Mean duration of edema was reported as 11.4 days (S.D +/- 12). Recurrent edema frequently occurred with limb activity. Pain was scored on a scale of 1 to 10, with a mean score of 4.8 (SD +/- 2.7). Mean duration of pain was reported as 7.8 days (SD +/- 6.4). Thirty patients required accommodation for ambulation including crutches (n = 11), limp (n = 11), and no shoes or loose shoes (n = 14). Of the 26 patients bitten on the hand or finger, duration of reduced function persisted for a mean of 14.3 days (SD +/- 10.4) and reduction of hand strength persisted for a mean of 22 days (SD +/- 25.5). Five patients had poorly healing wounds at the bite site which persisted from 14 to 77 days with a mean of 45 days (SD +/- 22.8)

CONCLUSION

In this study snakebite resulted in significant duration and extent of morbidity in a majority of patients.

Copperhead envenomations in the Carolinas

INTRODUCTION

Although the copperhead (Akistrodon contortrix) is responsible for most Crotaline envenomations in the Carolinas, manifestations and treatment are poorly characterized.

OBJECTIVE

We sought to describe the clinical course after copperhead bites.

METHOD

Structured review of copperhead exposures reported to a regional poison center from 1997-2000. Hospital records were reviewed when available. Phone followup was attempted.

RESULTS

A total of 178 cases were identified. Of these 75% were males. The median age was 31 yr (range 2-93). The bite site included hand (52%), foot (36%), leg (7%), and arm (5%). Classification included dry (7%), mild (48%), moderate (39%), and severe (6%). The most common symptom was pain (93%). Local findings included swelling (94%), fang marks (93%), ecchymosis (53%), erythema (37%), bullae (13%), and tissue necrosis (8%). Eleven of 37 patients developed abnormal PT and/or PTT. Two patients bled. Patients were treated at a healthcare facility in 160 cases, with 79 patients admitted. Opioid analgesics were the most common therapy (81%). Equine-derived antivenin was given in 14 cases (range 2-30 vials). Antivenin reactions developed in three. Two patients received blood products. Surgical treatment included debridement (6), grafting (2), digit amputation (1), digit dermotomy (1), and fasciotomy (1). No patients died. In followup, 18 patients reported limb dysfunction ranging from 5-365 days.

CONCLUSION

Copperhead bites typically result in mild to moderate envenomation due to local tissue effects. Significant systemic manifestations are rare. Limb dysfunction can be prolonged.