Antivenom Therapy for Crotaline Snakebites: Has the Poison Control Center Provided Effective Guidelines?

The Clinical Usefulness of Taiwan Bivalent Freeze-Dried Hemorrhagic Antivenom in Protobothrops mucrosquamatus- and Viridovipera stejnegeri-Envenomed Patients

Snakebites from Protobothrops mucrosquamatus (Taiwan habus) and Viridovipera stejnegeri (green bamboo vipers) account for the most venomous snakebites in Taiwan. The bivalent freeze-dried hemorrhagic (FH) antivenom is employed to treat these two snakebite patients without a strict clinical trial. We evaluated the clinical usefulness of Taiwan bivalent freeze-dried hemorrhagic (FH) antivenom in Taiwan habu- and green bamboo viper-envenomed patients. We checked ELISA- based serum venom antigen levels before and after FH antivenom to evaluate FH's ability to neutralize patients' serum snake venom and its usefulness in reducing limb swelling after snakebites. Patients who had higher serum venom antigen levels had more severe limb swelling. Of the 33 enrolled patients, most of their snake venom antigen levels were undetected after the appliance of antivenom. Most enrolled patients (25/33) had their limb swelling subside within 12 h after antivenom treatment. The failure to reduce limb swelling was probably due to an inadequate antivenom dose applied in more severely envenomated patients. Our data indicate the feasibility of the FH antivenom in effectively eliminating venom and resolving the affected limb swelling caused by Taiwan habu and green bamboo viper bites.

Prediction of Compartment Syndrome after Protobothrops mucrosquamatus Snakebite by Diastolic Retrograde Arterial Flow: A Case Report

Post-snakebite compartment syndrome (PSCS) is an uncommon but dangerous condition. Compartment syndrome-like symptoms after snakebite by Protobothrops mucrosquamatus (P. mucrosquamatus) are not effective in guiding fasciotomy. Objective evaluation of intracompartmental pressure measurements in patients with suspected PSCS is recommended. However, there is a lack of consensus regarding PSCS and indications for surgical intervention, including the threshold value of chamber pressure. In addition, intracompartmental pressure measurements may not be readily available in all emergency service settings. Measuring intracompartmental pressure in all snakebite patients for early diagnosis of PSCS is impractical. Therefore, identifying risk factors, continuous real-time monitoring tools, and predictive factors for PSCS are important. Sonography has proved useful in identifying the location and extension of edema after a snakebite. In this study, we attempted to use point-of-care ultrasound to manage PSCS in real-time. Here, we describe a rare case of snakebite from P. mucrosquamatus. PSCS was considered as diastolic retrograde arterial flow (DRAF) was noted in the affected limb with a cobblestone-like appearance in the subcutaneous area, indicating that the target artery was compressed. The DRAF sign requires physicians to aggressively administer antivenom to salvage the limb. The patient was administered 31 vials of P. mucrosquamatus antivenom, and fasciotomy was not performed. DRAF is an early sign of the prediction of PSCS.

The role of a point-of-care ultrasound protocol in facilitating clinical decisions for snakebite envenomation in Taiwan: a pilot study

BACKGROUND

The incidence of acute compartment syndrome (ACS) following snakebite envenomation may be seriously overestimated in Taiwan. Snakebite-induced ACS is difficult to determine solely by clinical examination. Snakebite patients previously underwent surgical intervention based on speculation and general clinical examinations suggesting ACS presentations instead of direct intracompartmental pressure (IP) measurement prior to fasciotomy. Point-of-care ultrasound (POCUS) is a relatively widely available noninvasive tool. This study aimed to evaluate snakebite-envenomated patients for the presence of subcutaneous edema and diastolic retrograde arterial flow (DRAF).

MATERIALS AND METHODS

Snakebite patients were prospectively recruited between 2017 and 2019. All patients were examined with POCUS to locate edema and directly visualize and measure the arterial flow in the compressed artery. The presence of DRAF in the compressed artery is suggestive of ACS development because when compartment space restriction occurs, increased retrograde arterial flow is observed in the artery.

RESULTS

Twenty-seven snakebite patients were analyzed. Seventeen patients (63%) were bitten by Crotalinae snakes, seven (26%) by Colubridae, one (4%) by Elapidae, and two (7%) had unidentified snakebites. All Crotalinae bit patients received antivenom, had subcutaneous edema and lacked DRAF in a POCUS examination series.

DISCUSSION

POCUS facilitates clinical decisions for snakebite envenomation. We also highlighted that the anatomic site of the snakebite is an important factor affecting the prognosis of the wounds. There were limitations of this study, including a small number of patients and no comparison with the generally accepted invasive evaluation for ACS.

CONCLUSIONS

We are unable to state that POCUS is a valid surrogate measurement of ACS from this study but see this as a starting point to develop further research in this area. Further study will be needed to better define the utility of POCUS in patients envenomated by snakes throughout the world.

The Treatment of Unidentified Hematotoxic Snake Envenomation and the Clinical Manifestations of a Protobothrops kelomohy Bite

Hematotoxic snake envenomation is clinically important and has serious complications. This case report describes the clinical manifestations of a bite from a newly described species of hematotoxic snake and the outcomes of treatment using locally available antivenom and supportive management. A 39-y-old male was bitten on his right ankle by an unidentified snake. The patient developed coagulopathy, rhabdomyolysis, and clinical signs of compartment syndrome of his right leg within the first day. Eight doses (30 mL, or 3 vials per dose), or a total of 240 mL, of hemato-polyvalent antivenin (Thai Red Cross, Thailand) were given. Aggressive intravenous hydration and alkalinization of urine were performed, and a fasciotomy was performed for the treatment of suspected compartment syndrome. The patient's clinical symptoms and laboratory results indicated progressive improvement during the 5 d of hospitalization. The snake was later identified as Protobothrops kelomohy, a novel snake species with no clinical data available regarding its envenomation of humans. This case shows that P kelomohy envenomation can produce severe effects that occur both locally and systemically. The benefits of the use of polyvalent antivenom in this situation were unclear. However, with supportive treatment in conjunction with serial clinical and laboratory monitoring, the patient recovered, albeit after 7 d of hospitalization.

Effects of Sodium Silicate Complex against Hemorrhagic Activities Induced by Protobothrops mucrosquamatus Venom

Protobothrops mucrosquamatus poses a serious medical threat to humans in Southern and Southeastern Asia. Hemorrhage is one of the conspicuous toxicities related to the pathology of P. mucrosquamatus envenoming. Previous in vitro and in vivo studies showed that a silica-derived reagent, sodium silicate complex (SSC), was able to neutralize hemorrhagic and proteolytic activities induced by pit viper venoms, including Crotalus atrox, Agkistrodon contortrix contortrix and Agkistrodon piscivorus leucostoma. In this study, we validated that SSC could neutralize enzymatic and toxic effects caused by the venom of P. mucrosquamatus. We found that SSC inhibited the hemolytic and proteolytic activities induced by P. mucrosquamatus venom in vitro. In addition, we demonstrated that SSC could block intradermal hemorrhage caused by P. mucrosquamatus venom in a mouse model. Finally, SSC could neutralize lethal effects of P. mucrosquamatus venom in the mice. Therefore, SSC is a candidate for further development as a potential onsite first-aid treatment for P. mucrosquamatus envenoming.

Benefits of Early In-Hospital Antivenom Administration to Patients with Protobothrops mucrosquamatus Envenomation

Protobothrops mucrosquamatus is one of the common venomous snakes in Southeast Asia. This retrospective cohort study conducted in six medical institutions in Taiwan aimed to obtain information on the optimal management strategies for P. mucrosquamatus snakebite envenomation. Data were extracted from the Chang Gung Research Database from January 2006 to December 2016. The association between early antivenom administration and patient demographics, pain requiring treatment with analgesic injections, and hospital length of stay was analyzed. A total of 195 patients were enrolled; 130 were administered antivenom within 1 hour after emergency department arrival (early group), whereas 65 were treated later than 1 hour after arrival (late group). No in-hospital mortality was identified. The difference in surgical intervention rates between the early and late groups was statistically insignificant (P = 0.417). Compared with the early group, the late group showed a higher rate of antivenom skin test performance (46.9% versus 63.1%, respectively, P = 0.033), longer hospital stay (42 ± 62 hours versus 99 ± 70 hours, respectively, P = 0.016), and higher rate of incidences of pain requiring treatment with analgesic injections (29.2% versus 46.2%, respectively, P = 0.019). After adjusting for confounding factors, early antivenom administration was associated with decreased pain requiring treatment with analgesic injections (adjusted odds ratio: 0.51, 95% CI: 0.260-0.985). Antivenom administration within 1 hour of arrival was associated with a decreased likelihood of experiencing pain and hospital length of stay in patients with P. mucrosquamatus snakebites. Antivenom skin testing was associated with delays in antivenom administration.

Protobothrops mucrosquamatus Bites to the Head: Clinical Spectrum from Case Series

Protobothrops mucrosquamatus (Trimeresurus mucrosquamatus) is a medically important species of pit viper with a wide geographic distribution in Southeast Asia. Bites by P. mucrosquamatus mostly involve the extremities. Little is known about the toxic effects of P. mucrosquamatus envenoming to the head because of the infrequency of such occurrence. To better delineate the clinical manifestations of envenoming to the head, we report three patients who suffered from P. mucrosquamatus bites to the head and were treated successfully. All three patients developed progressive soft tissue swelling extending from head to neck, with two patients expanding further onto the anterior chest wall. Mild thrombocytopenia was noted in two patients. One patient had transient acute renal impairment and airway obstruction, necessitating emergent intubation. All three patients received high doses of species-specific antivenom with recovery within 1 week. No adverse reactions to antivenom were observed.

Contributing Factors for Complications and Outcomes in Patients With Snakebite: Experience in a Medical Center in Southern Taiwan

OBJECTIVES

Snakebite usually results in various complications, such as significant soft tissue damage, infection, hematological, and neurological deficit. Surgical intervention, usually, is indicated in patients with tissue necrosis, infection, and compartment syndrome. To identify the contributing factors for complications and outcomes in different patients with snakebite so that outcomes can be evaluated and treatment of such patients can be initiated at the earliest.

METHODS

Information was collected regarding age, sex, underlying disease, species of snake, and the course of treatment of the victims of snakebite who visited the emergency department of a medical center in southern Taiwan between 2004 and 2014. The data obtained were analyzed using SPSS 20.0.

RESULTS

The bites from Taiwan cobra (Naja naja atra) significantly resulted in more complications than those from other snakes and required surgical intervention. The use of antivenin and antibiotics, immediate presentation to the hospital, and the location of the bite also were significant contributing factors.

CONCLUSIONS

Taiwan cobra significantly results in higher possibility of prolonged hospitalization, operation, tissue necrosis, infection, and necrotizing fasciitis. Location of the bite, immediate presentation to the hospital, and use of antivenin and antibiotics affect the outcome of snakebite. Knowledge of these factors will help in a better management of patients with snakebite.

Bungarus multicinctus multicinctus Snakebite in Taiwan

AbstractAlthough specific antivenom is available in Taiwan, respiratory failure and general pain frequently accompany Bungarus multicinctus envenomation and there have been few reports on the management of B. multicinctus envenomation. We retrospectively analyzed 44 cases of B. multicinctus bite admitted to Taichung Veterans General Hospital (VGH) or to Taipei VGH. Demographic data, treatment, and outcome of patients with and without respiratory failure were compared. In this study, 20.5% patients had bites without noticeable signs or symptoms of significant envenoming, 27.3% developed respiratory failure, and 27.3% experienced general pain. Bivalent specific antivenom for B. multicinctus and N. atra was administered in all envenomed cases. Respiratory failure occurred 1.5-6.5 hours post-bite and general pain occurred 1-12 hours post-bite. Specific antivenom for B. multicinctus and N. atra at the recommended dose (i.e., 2-4 vials) might not effectively prevent respiratory failure and pain. Respiratory failure, general pain, and autonomic effects after B. multicinctus bite were probably caused, at least partly, by β-bungarotoxin. Although general weakness, ptosis, dysarthria, and dilated pupils were significantly associated with respiratory failure, their predictive value could not be accurately determined in such a retrospective study. Due to the rapid onset of respiratory failure, every suspected envenomed case thus should be closely monitored in the first few hours. We recommend the initial administration of four vials of antivenom in all envenomation cases, and a subsequent four vials be considered if the patient's condition is deteriorating. Prospective evaluation of the antivenom dosing regimen is urgently needed to improve B. multicinctus envenomation treatment.

Naja atra snakebite in Taiwan

BACKGROUND

Naja atra snakebite is uncommon in Taiwan and causes distinct effects on its victims. Although the Taiwan government produces its own specific antivenom, little information on the management of N. atra snakebite is available.

MATERIALS AND METHODS

We retrospectively evaluated 183 patients admitted to two medical centers. Of these, 45 were identified as definite cases of N. atra snakebite, 86 as suspected cases, and 52 as clinical cases. Demographic data, symptomatology, and management were compared between these case groups.

RESULTS

Symptomatology and management were similar in the three groups. Among the 183 patients, 10 (5.5%) were asymptomatic and nine (4.9%) had transient and partial ptosis or body weakness. The principal effects were local tissue swelling and pain in 173 patients (94.5%), followed by clinically suspected wound infection in 148 (80.9%), skin necrosis in 120 (65.6%), necrotizing soft tissue infection in 77 (42.1%), fever in 59 (32.2%), and gastrointestinal effects in 53 (29%). The median total dose of specific antivenom needed to treat N. atra envenoming was 10 vials. In the envenomed patients, debridement was required in 74 patients (42.8%), fasciotomy/fasciectomy in 46 (26.6%), and finger or toe amputation in seven (4%). The first operation was performed at a median of 3.5 days after the bite.

DISCUSSION AND CONCLUSIONS

Based on these typical manifestations, clinical diagnosis of N. atra snakebites may be feasible and practical. In contrast to other snakes of Elapidae family, N. atra bite did not cause serious neurological effects. Early surgical consultation should be obtained because half of the patients underwent surgery due to infectious complications. Acute compartment syndrome was the surgical indication in rare cases; however, overestimation of the incidence may have occurred. This syndrome should be confirmed by serial intracompartmental pressure monitoring instead of only physical examination, and a sufficient dose of antivenom should be given prior to surgical decompression.

Predictors of the development of post-snakebite compartment syndrome

Background

To identify the factors associated with the development of post-snakebite compartment syndrome (PSCS) in snakebite patients and to analyze the clinical prognosis of these patients.

Methods

We retrospectively reviewed the medical records of patients who presented to our institution with snakebites from March 2009 to December 2012. The clinical data, hospital course and outcome were all recorded.

Results

A total of 136 patients were included in the present study. Nine patients developed PSCS and underwent fasciotomy. Relative to the non-PSCS group, the PSCS group demonstrated a significant increase in the white blood cell count (WBC, p = 0.006), segment form (Seg, p ≤ 0.001), aspartate aminotransferase level (AST, p = 0.002) and alanine aminotransferase level (ALT, p = 0.008). Elevated WBC count and AST level were identified as independent risk factors for PSCS (p = 0.028 and 0.037, respectively) in a multivariate analysis.

Conclusions

Snakebite patients have a high likelihood of developing locoregional complications such as PSCS. Symptomatic snakebite patients should be observed for at least 48 h, and increased WBC counts and AST levels are risk factors for PSCS.

Pattern of Use of Antibiotics Following Snake Bite in a Tertiary Care Hospital

INTRODUCTION

There are several conflicting recommendations on the use of antibiotics in snakebite victims. This study aimed to identify the pattern of antibiotics used following snake envenomation in a tertiary care hospital of Kerala.

MATERIALS AND METHODS

Retrospective review of case records from January to August 2011 was done and all the cases filed as snakebite were reviewed and details entered in a structured performa. Data was analysed using SPSS 16 and results were expressed mainly using descriptive statistics.

RESULTS

Three hundred and thirteen cases were evaluated with mean age 37.58± 14.54 year and 51.1% were males. Out of total, 94.6% received antibiotics of which 88.85% were oral, 8.1% parenteral and 3.04% both. There were total 454 prescriptions of antibiotics. In all seven different types of antibiotics were prescribed alone or in combination of which Ampicillin (205) was the commonest followed by Cloxacillin (194). The mean antibiotic usage was 1.46±0.716 per patient and the mean duration of antibiotic use was 3.16±1.446 days. In patients with no envenomation the mainly prescribed antibiotic was Cloxacillin (126). Intravenous antibiotics like Piperacillin plus Tazobactam were given only in patients with either local or systemic envenomation.

CONCLUSION

The main pattern of use of antibiotics following snakebite envenomation is Ampicillin alone or in combination empirically, Cloxacillin prophylatically and Piperacillin with Tazobactam for severe established infections. The choice of antibiotics is based on the clinician's discretion. Since the study setting is in a developing country the prophylactic use of antibiotics may be justified weighing the concerns of secondary infections.

Bacterial infection in association with snakebite: a 10-year experience in a northern Taiwan medical center

BACKGROUND

Microbiological data of secondary wound infections following snakebites is rarely reported in Taiwan. The objective of this study was to assess the secondary wound infection after venomous snakebites.

METHODS

We conducted a 10-year retrospective survey on patients admitted for venomous snakebites and microbiological data of wound cultures at a medical center in northern Taiwan.

RESULTS

Between April 2001 and April 2010, 231 patients who experienced snakebites were included. Male predominated, accounting for 62.3% (144). The age range of patients was 4-95 years. Ninety-five (41.1%) people were bitten by Trimeresurus mucrosquamatus, followed by Tstejnegeri, and cobra. A total of 61 pathogens were obtained from 21 patients. Thirty-nine (63.9%) isolates were gram-negative bacteria, 14 (23%) gram-positive pathogens, and 8 (13.1%) anaerobic pathogens. There were 17 patients bitten by cobra in these 21 patients. Morganella morganii and Enterococcus species were the most common pathogens identified in the wound cultures.

CONCLUSION

Cobra bite causes more severe bacterial infection than other kinds of snakebites. Oral amoxicillin/clavulanate plus ciprofloxacin or parenteral piperacillin/tazobactam alone can be the choices for empirical or definitive treatment, and surgical intervention should be considered for established invasive soft tissue infections.