Whole Blood Clotting Test Research Articles

Clinical Profile and Outcome of Snake Bite Patients from Tertiary Healthcare Center: In Sub-Himalayan Region: A Medical College-based Study.

Snake bite is an emergency in tropical and subtropical countries. It is a neglected disease and is most commonly seen in rural setups, where people are ignorant about the venomous snake bites. It results in increased mortality and morbidity because precious time is wasted, either in consulting traditional healers or waiting for the development of signs and symptoms of envenomation. Then only the patient is shifted to a health center. Here we studied the clinical profile, management, and outcome of snake bite patients. This study was done by retrieving the records of patients with snake bites admitted to the Department of Medicine, Indira Gandhi Medical College & Hospital, Shimla, from 1st January 2017 through December 2019. The recorded data was entered in a precoded performa, and analysis was done with respect to various variables. We evaluated the records of 190 patients. The incidence of the bite was higher among females, 62.1% (n = 118). The commonest age group involved was 21-50 years, 70.1% (n = 34). In 55.8% (n = 106), the site of the bite was the upper limb. The daytime bite was present in 54.7% (n = 106). The maximum incidence of snake bites was found during the rainy season, 81.5% (n = 155). 28.4% (n = 54) of patients presented within 6 hours of the bite. Coagulopathy [whole blood clotting test (WBCT) of >20 minutes] and neurotoxicity were seen in 77.9 and 7.9% of patients, respectively. Anti-snake venom (ASV) was given to 87.8% (n = 167) of patients. In 80% (n = 152) of the cases, hospital stay was up to 3 days. Mortality was seen in only two (1.05%) cases. There is a need to create awareness among the community, particularly in rural areas, about snake bite envenomation and early transportation of victims to the nearest health center. Training of health professionals is also needed to manage cases of snake bites efficiently and judiciously, thereby reducing morbidity and morbidity.

Gelatin/calcium chloride electrospun nanofibers for rapid hemostasis.

Blood coagulation is the body's main defense to bleeding caused by trauma and is divided into endogenous and exogenous pathways. Calcium ions play a very important role in the process of blood coagulation, as the ions activate the many enzymes that are required for coagulation. In this paper, gelatin hemostatic membranes containing calcium ions were prepared by electrospinning. The fibers were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The biocompatibility and coagulation processes using the calcium ion-containing gelatin fibrous membranes were evaluated in vitro with dynamic whole-blood coagulation tests, hemolysis tests, coagulation time tests, and platelet adhesion tests. It was demonstrated that the calcium ion-containing gelatin membranes had lower hemolysis rates and shorter clotting times than commercially available hemostatic sponges and hemostatic gauzes. In vivo hemostasis experiments were also conducted on the tail vein and liver of mice. Animal experiments demonstrated that the incorporation of calcium ions into the electrospun gelatin membranes promoted platelet aggregation, ensured adhesion of the electrospun membrane to the wound and reduced the bleeding volume and hemostasis time. The composite calcium ion-gelatin electrospun membranes exhibited good in vivo and in vitro hemostatic abilities and accelerated blood clotting by stimulating the coagulation pathway to promote platelet aggregation at the wounds and the formation of mature blood clots for a new approach for acute trauma treatment.

Comparison of bedside clotting tests for detecting venom-induced consumption coagulopathy following Sri Lankan viper envenoming

Background The whole blood clotting test (WBCT) is commonly used for diagnosing venom-induced consumption coagulopathy (VICC) in resource-poor settings. We aimed to investigate the diagnostic accuracy of the WBCT and capillary blood clotting test (CBCT) for detecting VICC in viper envenoming in Sri Lanka. Methods All confirmed snakebites admitted to Teaching Hospital Anuradhapura from July 2020 to June 2021 were included. On admission, WBCTs after 15, 20 and 25 min observation times (WBCT-15, WBCT-20 and WBCT-25) and CBCT observed in 30 s intervals (CBCT-t), 5 and 10 min CBCT (CBCT-5 and CBCT-10) were done. Blood was collected simultaneously for prothrombin time (PT)/international normalized ratio (INR) and plasma fibrinogen. We defined VICC as an INR >1.5 (Incomplete VICC = INR>1.5 and complete VICC = ≥3.0). Results A total of 272 confirmed snakebites (Russell’s viper[76], hump-nosed viper[89], non-venomous snakes[51] and unidentified bites[56]) were recruited (median age: 42 y [interquartile range: 30- 53 y]; 189 males [69%]). On admission, 82 (30%) had incomplete VICC (INR >1.5 and <3) and 77 (28%) had complete VICC (INR ≥3). Sixteen (6%) developed clinically apparent bleeding. The WBCT-15 had the best sensitivity of 47% for detecting VICC and 68% for complete VICC. The sensitivities of the WBCT-20, WBCT-25, CBCT-5 and CBCT-10 was 30–35%. The sensitivities of all tests were better in detecting complete VICC, VICC in Russell’s viper bites and more than 2 h post-bite. The WBCT-15 test had a sensitivity of 76% for VICC in confirmed Russell’s viper bites. For detection of VICC, CBCT-t had an an excellent sensitivity of 97%, but a poor specificity of 35% for an optimal cut-off of >6.25 min. Conclusion WBCTs are poorly diagnostic for VICC in Russell’s viper and hump-nosed viper envenoming, missing up to two-thirds of patients for some tests. The WBCT-15 was the best test, improving for more severe VICC and greater than 2 h post-bite.

Point-of-care infrared thermal imaging for differentiating venomous snakebites from non-venomous and dry bites.

Local envenomation following snakebites is accompanied by thermal changes, which could be visualized using infrared imaging. We explored whether infrared thermal imaging could be used to differentiate venomous snakebites from non-venomous and dry bites. We prospectively enrolled adult patients with a history of snakebite in the past 24 hours presenting to the emergency of a teaching hospital in southern India. A standardized clinical evaluation for symptoms and signs of envenomation including 20-minute whole-blood clotting test and prothrombin time was performed to assess envenomation status. Infrared thermal imaging was done at enrolment, 6 hours, and 24 hours later using a smartphone-based device under ambient conditions. Processed infrared thermal images were independently interpreted twice by a reference rater and once by three novice raters. We studied 89 patients; 60 (67%) of them were male. Median (IQR) time from bite to enrolment was 11 (6.5-15) hours; 21 (24%) patients were enrolled within 6 hours of snakebite. In all, 48 patients had local envenomation with/without systemic envenomation, and 35 patients were classified as non-venomous/dry bites. Envenomation status was unclear in six patients. At enrolment, area of increased temperature around the bite site (Hot spot) was evident on infrared thermal imaging in 45 of the 48 patients with envenomation, while hot spot was evident in only 6 of the 35 patients without envenomation. Presence of hot spot on baseline infrared thermal images had a sensitivity of 93.7% (95% CI 82.8% to 98.7%) and a specificity of 82.9% (66.3% to 93.4%) to differentiate envenomed patients from those without envenomation. Interrater agreement for identifying hot spots was more than substantial (Kappa statistic >0.85), and intrarater agreement was almost perfect (Kappa = 0.93). Paradoxical thermal changes were observed in 14 patients. Point-of-care infrared thermal imaging could be useful in the early identification of non-venomous and dry snakebites.

COAGULATION PROFILE IN CASES OF SNAKE BITES.

Introduction Snake bite is an important occupational and rural hazard because India had always been a land of Exotic snakes. India is inhabited by more than 60 species of venomous snakes. Objectives 1) To study the coagulation profile in cases of snake bites. 2) To study different clinical manifestation in cases of snake bites. 3) To correlate severity of clinical findings with the results of coagulation profile. Methods- The current studyis a two year cross sectional study, study includes snake bite coming to tertiary care hospital during the period two years. A written informed assent was taken from all the cases remembered for the examination for the treatment, investigations and research purpose. Results- In the current study, during the period of two years, a total 165 study subjects, 91 (55.2%) patients had vasculotoxic bite, Mean age in the current investigation was 34.7 years. The male to female proportion in the current study was 1.6:1. Farmers were affected more with 111 (70.2%) Majority of the cases were admitted within 6 hours of snake bite comprising of 85 (53.8%) cases.Local pain was symptom observed in 133 (84.2%) cases followed by swelling at the site of bite which comprised of 127 (80.4%) cases. The most common presentation of envenomation seen in 60 (65.9%) cases, 20 minute whole blood clotting test (WBCT) in 53 (58.2%) vasculotoxicstudy subjects. APTT was increased in 67 (73.6%) out of 91 vasculotoxic snake bite ases. Bleeding time was increased in 13 (14. 28%) out of 91 vasculotoxicstudy subjects. Thrombocytopenia was seen in 26 (28.6%) out of 91 vasculotoxicstudy subjects. Acute renal failure developed in 11 out of16 cases. Thus, clinical severity is well correlated with the deranged coagulation profile and increased hospital stay. There was no mortality reported in our study. Conclusions Coagulation tests should be routinely performed on all patients presenting to the emergency department with complaints of snake bite, as early detection of coagulopathy reduces the morbidity and prevents the mortality in vasculotoxicstudy subjects.

Trimeresurus Malabaricus Bites: Need of Species-specific Management for Snakebites.

Dear Editor, Apart from the “big four” species of venomous snakes, the pit vipers (hump nosed, Malabar, bamboo) and banded kraits are the other types seen in Kerala. Malabar pit viper (Trimeresurus malabaricus) is an elusive species, seen in the forests of the Western Ghats. We have come across the case of a 54-year-old healthy female after a snakebite. On examination, she had a bite mark on the right parietal region of the scalp, with swelling and tenderness in the surrounding area extending to the neck. She also had multiple tender lymph nodes in the right jugulodigastric and posterior auricular groups [Figure 1a]. She had no features of neurotoxicity. Her 20-min whole blood clotting test (WBCT) was prolonged. The snake was later identified and confirmed to be a Malabar pit viper [Figure 1b]. 20-min WBCT and coagulation profiles repeated periodically for the next 48 hr were normal. Even though characteristics of pit viper bites have been previously profiled,[12] the incidence of Malabar pit viper bites is less. Envenomation following Malabar pit viper bites results in significant local reaction and hematotoxicity, along with milder forms of renal impairment. The Polyvalent anti-snake venom (ASV) used in India does not contain antibodies against pit viper venom and since cross neutralization with venoms of other species of snakes has not been proven,[3] its use is considered futile the treatment. With snakebites other than the “big four” snakes covered by the polyvalent ASV on the rise, the need for newer techniques for identification of snakes and development of species and region-specific antivenom is the need of the hour.Figure 1: (a) Enlarged right jugulodigastric lymph node with swelling seen on the right neck. (b) Photograph of the offending snake Malabar pit viper (Trimeresurus malabaricus) on the tree branchDeclaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Characterization and Hemostatic Potential of Two Kaolins from Southern China

The physicochemical properties and potential hemostatic application of Wenchang kaolin and Maoming kaolin were inspected and evaluated. Chemical composition analysis, Fourier transform infrared (FTIR) spectroscopy, surface area determination, X-ray diffraction, particle size, scanning electron microscopy (SEM) observations, and zeta potential analysis were performed to quantify the physical and chemical properties of the two kaolins. The results showed that both kaolins have typical FTIR bands of kaolinite with a weight fraction for kaolinite over 90 wt%. Larger conglobate aggregates of Maoming kaolin demonstrated wider particle size distributions with two peaks at 3.17 and 35.57 μm, while the book-like Wenchang kaolin had narrow particle size distribution, with a frequent size of 5.64 μm. Furthermore, thrombelastography, the whole blood clotting tests (WBCT), plasma recalcification time (PRT) measurement, and MTT assay were performed to measure the clotting activities and biocompatibility of the two kaolins. The results showed that both kaolins could promote blood coagulation with good cytocompatibility, while Wenchang kaolin had a better procoagulant activity than Maoming kaolin. These findings demonstrated Wenchang kaolin to be a more suitable local source material for application as a hemostatic agent.

Functional Coagulation Differences Between Lobar and Deep Intracerebral Hemorrhage Detected by Rotational Thromboelastometry: A Pilot Study.

Lobar intracerebral hemorrhage (ICH) is known to have better clinical outcomes and preliminary evidence of less hematoma expansion compared to deep ICH. No functional coagulation differences between lobar and deep ICH have been identified using traditional plasma-based coagulation tests. We investigated for coagulation differences between lobar and deep ICH using whole-blood coagulation testing (Rotational Thromboelastometry: [ROTEM]). Clinical, radiographic, and laboratory data were prospectively collected for primary ICH patients enrolled in a single-center ICH study. Patients with preceding anticoagulant use or admission coagulopathy on traditional laboratory testing were excluded. Lobar and deep ICH patients receiving admission ROTEM were analyzed. Linear regression was used to assess the association of ICH location with coagulation test results after adjusting for potential confounders. There were 12 lobar and 19 deep ICH patients meeting inclusion criteria. Lobar ICH patients were significantly older and predominantly female. Lobar ICH had faster intrinsic pathway coagulation times (139.8 vs 203.2s; 95% CI - 179.91 to - 45.96; p = 0.002) on ROTEM testing compared to deep ICH after adjusting for age, sex, and hematoma volume. This revealed functional coagulation differences, specifically quicker clot formation in lobar compared to deep ICH. No differences were noted using traditional coagulation testing (prothrombin time/partial thromboplastin time/platelet count). Our pilot data may suggest that there are functional coagulation differences between lobar and deep ICH identified using ROTEM. Whole-blood coagulation testing may be useful in assessing coagulopathy in ICH patients and in determining reversal treatment paradigms, though further work is needed.

An introduction to point-of-care testing in extracorporeal circulation and LVADs.

There is a delicate balance between bleeding and clotting in patients on circuits such as ventricular assist devices or extracorporeal membrane oxygenation. Traditional coagulation tests, prothrombin time, activated partial thromboplastin time, and anti-factor Xa levels, are used to monitor patients on these devices. However, turnaround times and inability to assess global hemostasis, including platelets and fibrinogen have contributed to a recognition that faster, accurate, and more informative coagulation tests are needed. Activated clotting time is used to monitor heparin in patients on circuits and has the advantages of being a near-patient point-of-care test. However, its utility is limited to heparin monitoring. Viscoelastic tests (thromboelastometry and thromboelastography) are global, whole-blood coagulation tests, and whole-blood platelet aggregometry evaluates platelet function. Ideally, these tests can ensure that patients are within the therapeutic range of their antithrombotic medications, identify patients at risk for hemorrhagic or thrombotic complications, and guide management of acute bleeding complications. This ideal is currently hampered by a lack of studies that delineate clear ranges that are clinically relevant. Future research is needed to better understand the optimal use of point-of-care coagulation testing in patients on extracorporeal circuits and ventricular assist devices.

Delayed double reading of whole blood clotting test (WBCT) results at 20 and 30 minutes enhances diagnosis and treatment of viper envenomation

BackgroundThe whole blood clotting test (WBCT) is a simple test of coagulation that is often used in the assessment, diagnosis, and therapeutic monitoring of snakebite patients in sub-Saharan Africa. WBCT requires only a clean glass tube and several milliliters of venous blood and is ideal for use in poorly equipped health centers throughout the rural areas where 95% of snakebites occur. However, questions surrounding the accuracy and reliability of the test remain unanswered due to variations in testing conditions and a lack of comparative research with which to validate them. This is the first study to evaluate WBCT results at both 20-min (WBCT20) and 30-min (WBCT30) reading times in the same group of snakebite patients.MethodsIn order to define the best reading time, the authors compared the results of serial WBCT evaluation at both 20 and 30 min after collection in 23 patients treated for snake envenomation in Bembèrèkè, northern Benin.ResultsWBCT results were identical at both reading times in patients without coagulopathy or when coagulation was restored permanently following a single dose of antivenom. Out of 17 patients with coagulopathy, 14 showed discrepancies between WBCT20 and WBCT30 results in at least one pair of serial evaluations. These could be completely contradictory results (e.g. normal clot at WBCT20 and no clot at WBCT30) or a marked difference in the quality of the clot (e.g. no clotting activity at WBCT20 and an unstable partial clot at WBCT30). WBCT discrepancies were encountered most frequently in three situations: initial normalization of hemostasis following antivenom therapy, detection of a secondary resumption of coagulopathy, or final restoration of hemostasis after a secondary resumption had occurred.ConclusionsThis study suggests that the WBCT is robust and that a sequential reading should improve the diagnosis and monitoring of venom-induced coagulopathies. It also indicates the possibility of discrepancies in the sensitivity of WBCT20 and WBCT30 for detecting the resolution or reoccurrence of coagulopathy and identifies how these findings, if confirmed, may be used to increase the efficacy and efficiency of antivenom treatment in the field.

Utility of Clot Waveform Analysis in Russell's Viper Bite Victims with Hematotoxicity.

Introduction:In Russell's viper bites, due to the lack of a better alternative, whole blood clotting test (WBCT) remains the standard test even though its reliability and sensitivity has been shown to be low. Activated partial thromboplastin time (aPTT)-based clot waveform analysis (CWA) is an optic absorbance assay that can be used as a global clotting test. In this study, the objective was to assess the changes in CWA and to compare CWA to WBCT and aPTT in patients with Russell's viper envenomation.Methods:The datum was collected prospectively over 2 months as a pilot observational study in a tertiary care center. All proven cases of Russell's viper-envenomated individuals with preliminary CWA data and WBCT were included in the study. The clot wave (CW) of the five individuals, which met all the stringent inclusion criteria, was analyzed and interpreted.Results:CW absorbance sigmoid waveform was deranged in all 5 cases, of which 4 showed a change in CWA even before an abnormal aPTT. Three of the 5 had a normal WBCT but showed early changes in CWA. Atypical biphasic waveform reported in disseminated intravascular coagulation in other prior studies is seen in venom-induced consumptive coagulopathy also. In all patients where a second derivative was plotted, the second (lower) phase of the second derivative showed a slow rise to baseline.Conclusion:CWA showed changes which provided information earlier than the conventional coagulation studies in the snakebite victims studied. While aPTT or WBCT reflects clotting time, CWA conveys the dynamic process of clot formation and stabilization. CWA may reveal disorders of clotting in snakebite victims before the conventional tests become abnormal. Future research should assess the speed and accuracy of the test in diagnosing hemotoxic envenomation and its potential role in guiding antivenom therapy.

Effect of distance and delay in access to care on outcome of snakebite in rural north-eastern Nigeria

Snakebite envenoming is a major cause of morbidity and mortality in rural areas of the tropics. Timely administration of effective antivenom remains the mainstay of management. The study was a quantitative descriptive study aimed at exploring the causes and effects of delay, distance and time taken to access care on snakebite outcomes in Nigeria. All prospective snakebite victims reporting to Kaltungo General Hospital were enrolled. Data on demography, date and time bitten, date and time admitted, site of bite, circumstances of snakebite, responsible snake, clinical features, 20-minute whole-blood clotting test, antivenom administered and outcome were recorded. Delay arising from use of traditional first aid (TFA), time elapsed from snakebite to presentation and the shortest distance from bite location to the hospital was calculated or obtained using a global positioning system. The association between delay before hospital presentation and poor outcome was not statistically significant, even though there was a 2% higher likelihood of poor outcome among those with a 1-hour delay compared to those without delay (odds ratio 1.02, 95% confidence interval 1.00-1.03). There was no difference in distance from bite location to hospital between those with a poor outcome (74) compared to those with a good outcome (325). Those with a poor outcome had more severe envenomation requiring more antivenoms and longer hospital stays. Given poor access to antivenom therapy at distant locations &#8805;100 km, victims were more likely to use TFA such as black 'snake' stone, with consequent prolonged delays. Antivenoms should be more readily available at distant places. Community education on avoiding potentially harmful TFA and prompt access to care is recommended. There is a need to provide snakebite care to multiple peripheral, relatively more rural inaccessible areas.

Study of multi-functional electrospun composite nanofibrous mats for smart wound healing

Composite nanofibers derived from synthetic and natural polymers normally show desirable characteristics in biomedical applications. In this study, composite nanofibrous mats (denoted as CNMs) with diameters of around 300nm were fabricated facilely using blends of chitosan, gelatin and shape memory polyurethane (SMPU) by electrospinning and subsequent post-treatment with a silver nitrate solution. The obtained CNMs have shape memory effect and show desirable water vapor transmission ratio, surface wettability, satisfactory biological properties including antibacterial activity against the common Gram-negative and Gram-positive bacteria, cytocompatibility demonstrated to fibroblast, and the hemostatic property through a whole-blood clotting test. In addition, such CNMs can possibly benefit the wound healing through shape fixation-assisted easy processing and shape recovery-assisted closure of cracked wounds, which can be fine-tuned by pre-programming. Therefore, the CNMs presented in this study can be used as potential smart wound dressings.

Black hemostatic sponge based on facile prepared cross-linked graphene

In this study, we demonstrate for the first time the remarkable hemostatic performance of a cross-linked graphene sponge (CGS) as a superb hemostat. The CGS can absorb plasma immediately (<40ms) to form a blood cell layer and promotes subsequent clotting. The interaction between the interface of the CGS and blood cells reveals that the fast blood coagulation is primarily attributed to the enrichment of hemocytes and platelets on the wound surface. An in vitro dynamic whole-blood clotting test further highlights the effectiveness of the CGS. Considering the facile preparation, low cost, nontoxicity, and long shelf life of the portable black sponge, the CGS has great potential for trauma treatment.

Management of Snakebite and Systemic Envenomation in Rural Ecuador Using the 20-minute Whole Blood Clotting Test

In low-income countries, snakebites are frequently managed in rural areas in health centers with severely constrained resources. Many healthcare providers in these settings have limited access to the numerous and relatively expensive laboratory studies used to diagnose envenomation. The relatively simple and inexpensive 20-minute whole blood clotting test (WBCT) has been recommended by several international organizations for the diagnosis of certain venomous snakebites. This study proposes to confirm the utility of the WBCT as the sole laboratory diagnostic tool to determine systemic envenomation in hematotoxic snakebite management in severely resource-constrained areas of the world. The authors reviewed all 110 cases of snakebite during a 6-year period in a small hospital in rural Ecuador using the WBCT. All cases presented within 24 hours of snakebite. Twenty cases revealed normal coagulation with no clinical evidence of systemic envenomation. Ninety cases had no evidence of clot formation (positive WBCT) at 20 minutes, suggesting systemic envenomation. Of these 90 cases, according to a classification scale, 54 were mild, 26 were moderate, and 10 were severe envenomations requiring transfer to tertiary care. All mild and moderate systemic envenomations were successfully treated at the rural hospital. All severe envenomations were treated initially with antivenom before transfer to tertiary care. One patient with severe envenomation died in tertiary care. The WBCT was predictive of the presence or absence of systemic envenomation from snakebite in our region. The WBCT guided the successful management of mild and moderate systemic envenomation, and spared patients with no evidence of systemic envenomation from potential side effects of antivenom.

Bedside Whole-Blood Clotting Times: Validity after Snakebites

BackgroundVenomous snakebites contribute to morbidity and mortality throughout the world, most commonly in resource-poor areas, with about 2.5 million humans sustaining snakebites annually. Coagulopathy is a significant cause of both morbidity and mortality in these patients. In the absence of more sophisticated hematological studies or obvious physical findings, many clinicians must rely on whole-blood clotting times to assess whether their patients are coagulopathic. Alternative (bedside) methods to assess clotting times are often officially recommended and used, but have not been validated. ObjectiveWe assessed two bedside methods for measuring whole-blood clotting time after snakebites for their congruence with results from a hospital laboratory. MethodsOver a 5-month period, 46 sequential patients presenting with a possible snakebite had blood drawn for bedside (using syringe and ceftriaxone bottle as containers) and laboratory whole-blood clotting tests. All three tests used ∼5 mL whole blood and looked for any clot formation within 20 min. ResultsCompared to the laboratory, the syringe method correctly classified the patients 84.7% of the time (sensitivity 88.9%; specificity 82.4%). The bottle method correctly classified the patients 86.8% of the time (sensitivity 83.3%; specificity 90.0%). Comparing the area under the Receiver Operator Characteristics curves shows that both the syringe and bottle methods do not differ in their discrimination for identifying clotting. ConclusionsBoth the syringe and ceftriaxone bottle bedside clotting test methods appear to be accurate enough to help guide therapy after potential snake envenomations when formal laboratory testing is unavailable.

Epidemiology and outcome of snake bite cases evaluated at a Tertiary Care Hospital in Oman

To study the epidemiology of snake bite patients evaluated at the Royal Hospital, Muscat, Sultanate of Oman, and to study their clinical course and outcome. A retrospective study of 65 adult patients presenting at Royal Hospital following a snake bite from May 2006 to August 2008. The main symptoms were local pain at the bite site (26 patients, 40%) and swelling (17 patients, 26%). Only five patients (7.7%) had signs of bleeding. After assessment, only 47 of the 65 patients were admitted. White cell count (WCC) was raised in 15 cases (23%) on presentation to the emergency room. Prothrombin time was prolonged in 34 patients (52%) and APTT was prolonged in 25 patients (38%) on presentation. Thirty-six patients received anti-snake venom (antivenom) at a mean time of 8h after the bite and 4h after arrival in the emergency department. Patients with deranged coagulation profile needed a mean of fourteen vials of antivenom for correction of the abnormal coagulation profile. Two patients died: both had delayed presentation to the hospital. Patients with envenoming following snakebite should receive antivenom as soon as possible: delayed presentation or administration may be very dangerous. The decision to give antivenom should be initiated as soon as possible after patients' arrival at the Emergency Department and the use of the whole blood clotting test (WBCT) may facilitate the early administration of antivenom.

Plastic containers and the whole-blood clotting test: glass remains the best option

This is the first study to identify normal whole-blood clotting times in various plastic containers and to identify the effect of the addition of various concentrations of Pseudechis australis (Mulga snake) venom on the clotting time in glass and plastic. Polycarbonate was identified as a potential alternative to glass as a testing container owing to a whole-blood clotting time within acceptable limits for a bedside test (mean 29.5 min) and equivalent performance to glass in the presence of P. australis venom. Other plastic containers (such as polypropylene and polyethylene) were found to be unsuitable owing to very prolonged clotting times (>60 min) or impaired performance in the presence of venom. Overall, owing to the variation between the performance of different plastics and the difficulty in differentiating between them, plastic containers cannot be recommended as an alternative to glass when performing the whole-blood clotting test for envenomed patients.

Venomous bites and stings

Abstract Venomous bites and stings occur worldwide and are a particular problem for rural workers in the remote tropics. They are caused by a large variety of terrestrial and marine animals and are associated with both mortality and morbidity. Most snakebites occur on the lower limbs; not all bites by venomous species lead to envenoming, but they may result in both local and systemic effects. Clinical features depend on the species of snake; elapids tend to cause minimal local damage and neurotoxicity, whereas vipers may cause local swelling and necrosis in addition to coagulopathy and shock. Careful clinical observation of patients after snakebite is crucial; the 20-minute whole-blood clotting test is useful in the diagnosis of some viper bites. Intravenous infusion of antivenom is the mainstay of treatment in those with clear signs of envenoming; the antivenom used should be appropriate to the biting species and the geographical region. The dose of antivenom is the same for adults and children, and supportive care (e.g. fluid replacement in shock, respiratory support for severe neurotoxicity) is crucial. Scorpion stings commonly cause pain, but in children may lead to systemic envenoming with transmitter release from autonomic nerves; antivenom is effective in some regions. There are many venomous spider species; some cause local skin necrosis, others cause severe systemic envenoming. Many marine animals are venomous, often causing severe pain at the site of the sting. Some jellyfish (e.g. box jellyfish) can cause life-threatening systemic envenoming.

The Haemocompatibility of Biomaterials In Vitro: Investigations on the Mechanism of the Whole-blood Clot Formation Test

Twenty years ago Imai &amp; Nose introduced a whole-blood clotting test for the estimation of haemocompatibility of biomaterials in vitro In our paper a modification of this assay is described and the mechanism of clot formation further elucidated. It was found that neither the inhibition of platelet function nor the removal of platelets from blood significantly changed the clot formation rate on glass and polyvinyl chloride in comparison to the rate tor whole blood. Scanning electron microscopy demonstrated that platelets were not involved in clot formation near the blood/biomaterial interface. Thus, it was concluded that the system of contact activation of the coagulation cascade dominates during clot formation under static conditions. The latter conclusion was supported by the fact that preadsorption of human serum albumin or human fibrinogen onto the glass plates used, decreased the clot formation rate in the same manner.