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Geoffrey K Isbister

Publications and source records attributed to Geoffrey K Isbister.

At least 37 records · Page 2Linked to original sources
PubMed2003

Suspected snakebite: one year prospective study of emergency department presentations.

AIM: Snakebite is an uncommon, but potentially life-threatening condition. The more common clinical scenario is suspected snake-bite. Our aim was to characterise the epidemiology, diagnosis and management of patients with suspected snakebites. METHODS: Prospective cohort study of patients presenting with suspected snakebites to a tertiary referral hospital serving a large rural region in tropical northern Australia where a standard admission protocol for suspected snakebites is used. RESULTS: Of 70 suspected snakebite cases, there were 45 definite bites: three severe envenomings (two western brown snakes [Pseudonaja nuchalis] and one mulga snake [Pseudechis australis]); seven mild/moderate envenomings by other snakes, two non-envenomings by identified P. nuchalis, five bites by identified non-venomous snakes and 28 definite bites without envenoming. The remaining 25 cases were either suspected bites (8), unlikely bites (15) and two people hit by snakes. Definite snake-bites occurred throughout the year, peaking in May and December. There were three severe envenomings (mainly coagulopathy), requiring antivenom treatment, but no deaths or major complications. Most patients had appropriate investigations. Of 47 venom detection kit swabs collected, 34 were not tested, venom was not detected in nine and was positive in the three envenomings with one false-positive tiger snake. Whole blood clotting time was highly sensitive for procoagulant coagulopathy and envenoming in this study. Median length of time from the bite to discharge was 20 h (interquartile range: 12-27). CONCLUSIONS: The study shows that although suspected snakebite was common, severe envenoming occurred in less than 5% of cases. The study supports the proposition that a structured approach and admission policy of suspected snakebites leads to the appropriate management of severe envenoming, with no cases discharged early and no cases of non-envenoming treated with antivenom.

Adolescent↗
PubMed2003

Presumed Angel's trumpet (Brugmansia) poisoning: clinical effects and epidemiology.

OBJECTIVE: To investigate the pattern and epidemiology of anticholinergic plant poisoning, and to characterize its time course and clinical features. METHODS: We reviewed all anticholinergic plant poisonings using a prospective database of all poisonings admitted to a major toxicology unit in Australia. All patients that presented with anticholinergic plant poisoning between July 1990 and June 2000 were included. Patient demographics, details of poisoning, diagnostic clinical features, adverse effects (seizures, arrhythmias, hypotension, accidental injury), and treatments required were obtained. Important diagnostic features were analysed and compared to previous studies. RESULTS: Thirty-three patients were presumed to have ingested Brugmansia spp. (Angel's trumpet) based on their description of the plant; median age 18 years (interquartile range 16-20); 82% males. Thirty-one ingested a brewed tea or parts of the plant (flower). Thirty-one used it recreationally. Common clinical features were: mydriasis (100%), mean duration 29 h (SD 13) and delirium (88%) with a mean duration of 18 h (SD 12). Tachycardia only occurred in 11 of the 33 patients (33%). In 24 patients where the time of ingestion was certain, 7 of 8 (88%) patients presenting within 5 h had tachycardia and only 5 out of 16 (31%) presenting after 5 h had tachycardia. There were no deaths, seizures or arrhythmias (excepting tachycardia). One patient had hypotension and two sustained accidental traumatic injuries. Nineteen patients required sedation, mainly with benzodiazepines. Physostigmine was used diagnostically in eight cases. CONCLUSIONS: Anticholinergic plant abuse is sporadic in nature. Most cases were moderate in severity, requiring sedation only, and severe toxicity was rare. Mydriasis and delirium were the commonest features, the later having important implications for management.

Adolescent↗
PubMed2003

Nefazodone poisoning: toxicokinetics and toxicodynamics using continuous data collection.

Nefazodone overdose has been reported infrequently. The commonest effects reported are drowsiness, nausea, dizziness, and vomiting, less commonly hypotension and bradycardia. We report a case of single-agent nefazodone poisoning. Serial drug concentrations were taken for quantification of parent drug and metabolites. Clinical findings were documented every 1 to 2 hours. We modeled both the toxicokinetics of nefazodone and correlated this with clinical effects and electrocardiograph (ECG) abnormalities. A 16-year-old female took 2.4 g of nefazodone. She had significant drowsiness in the first 6 hours, associated with hypotension (systolic BP < 90 mmHg; lowest BP 70/30 mmHg) for 18 hours, and mild bradycardia (slowest rate of 56 bpm). She had a prolonged QT/QTc which normalized over 24 hours. She was given charcoal and intravenous fluids and was observed carefully, recovering with no problems. The terminal elimination half-life for nefazodone was 8.3 hours, and its metabolite hydroxy(OH)-nefazodone was 14.6 hours. BP-time curves demonstrated an 18-hour period of hypotension. There was a significant correlation between systolic BPand OH-nefazodone (R2 = 0.602). HR remained between 56 and 66 bpm for 30 hours despite hypotension. QT was significantly correlated with nefazodone (R2 = 0.911) and OH-nefazodone (R2 = 0.797), but no significant relationship between QTc and drug concentrations. The case demonstrates that nefazodone may potentially cause cardiac toxicity, which appears to be concentration-dependent. Although QT was concentration-dependent, this would need confirmation with other cases. Bradycardia, hypotension, and drowsiness are the most significant effects and are maximal in the first 12 hours when parent and metabolite concentrations are high.

Adolescent↗
PubMed2003

Clinical toxinology--where are we now?

Clinical toxinology encompasses a broad range of medical conditions resulting from envenomation by venomous terrestrial and marine organisms, and also poisoning from ingestion of animal and plant toxins. Toxin-related disease is an important cause of morbidity and mortality worldwide, particularly in the tropical and subtropical continents. Snake bite is the single most important toxin-related disease, causing substantial mortality in many parts of Africa, Asia, and the Americas. The most important snake families are Viperidae and Elapidae, causing a range of clinical effects including local necrosis, neurotoxicity, coagulopathy and hemorrhage, myotoxicity and renal toxicity. These effects vary according to geography and group of snake. Arachnid envenomation results mainly in morbidity, particularly scorpion stings which can cause severe systemic envenomation. Spider bite is far less of a problem, and the majority of medically important cases can be attributed to widow spiders (Latrodectus spp.) and recluse spiders (Loxosceles spp.). Marine-related envenomations are common, but severe effects are less so. Plant and mushroom poisoning occur in most parts of the world, but the types and methods of poisoning vary considerably between continents. Management of toxin-related disease is often difficult, and in many cases meticulous supportive care is all that is available. The mainstay of treatment is the use of antivenoms for many envenomations and poisoning, although these do not exist for all dangerous organisms. Unfortunately antivenoms are not an economically viable product, so development and manufacture of these agents have been limited. This is now further worsened by a current shortage of antivenom. There is a need for improvement in the preventionand management of toxin-related disease. This will require well-designed studies to define the extent of the problem, initiatives to improve the prevention and management of these conditions, and development of new, and continuation of current, antivenom supplies.

Animals↗
PubMed2003

Antivenom treatment in arachnidism.

Envenomation by arachnids causes significant medical illness worldwide. Scorpion sting is the most important arachnid envenomation causing adult morbidity and pediatric mortality. Important groups of spiders include the widow spiders (Latrodectus spp.), the recluse spiders (Loxosceles spp.), and two spiders confined to single countries: the Australian funnel web spider (Atrax and Hadronyche spp.) and the armed spider (Phoneutria spp.) from Brazil. There are four widow spider antivenoms available, including the Australian redback spider antivenom and the American black widow antivenom. Despite good in vitro animal work demonstrating effective neutralization with these antivenoms, and cross-reactivity between many species, there continues to be a reluctance to use them in some countries. They are both associated with a relatively low rate of allergic reactions. Redback antivenom is routinely used by the intramuscular route, which may not be as effective as intravenous use based on clinical experience and animal studies. Antivenoms are available for Loxosceles spp., but there is little evidence to support their effectiveness, particularly against local effects. The Australian funnel web spider causes severe neurotoxic envenomation, and antivenom appears to be effective in reported cases. An antivenom exists for the Brazilian armed spider, but is used in only a minority of cases. Many scorpion antivenoms exist worldwide, but there remains significant controversy regarding their efficacy. Animal and human venom level studies demonstrate neutralization of circulating venom in systemic envenomation. Clinical experience in countries where antivenom has been introduced suggests it has reduced pediatric mortality. However, three controlled trials demonstrated that antivenom was not effective, but these included few severe cases. Until controlled trials of antivenom in systemically envenomated patients are undertaken, antivenom use appears justified in severe envenomation. Although envenomation from arthropods is common, no antivenoms exist for these, excepting Lonomia caterpillars in South America, and Ixodes paralysis ticks in Australia.

Animals↗
PubMed2003

Randomized controlled trial of topical aspirin in the treatment of bee and wasp stings.

BACKGROUND: The New South Wales Poisons Information Centre (NSW PIC) has been recommending the use of topical aspirin paste for bee and wasp stings since the early 1980s. Anecdotal evidence from calls suggested it was effective in reducing the swelling and duration of pain, but a literature search found no evidence to support this. OBJECTIVE: The objective of this study was to assess the effectiveness of advice given by a PIC to apply topical aspirin for the treatment of bee and wasp stings. METHODS: Patients were recruited from callers to the NSW PIC who reported a bee or wasp sting. They were randomly assigned, using a 2:1 ratio, to two different treatment advices: to apply an ice pack (control group), or to apply an ice pack and topical aspirin paste (treatment group). Initial follow-up was within 24-48 hours. Primary outcome was the presence of swelling at 12 hr. Secondary outcomes included the presence of pain at 12 hr, the presence of itchiness, and duration of redness. RESULTS: There were 37 patients who received treatment advice and 19 in the control group. Of the 37 patients advised to apply aspirin, 21 (57%) had no swelling at 12 hr compared with 14 of the 19 (74%) patients with ice alone (difference -17%; 95% CI: -47-12%; p = 0.26). Eighty-one percent (30/37) of patients advised to apply aspirin had no pain at 12 hr compared with (18/19) 95% of the others (-14%; 95% CI: -39-14%; p = 0.34). The median duration of redness was 6 hr [interquartile range (IQR): 2-48 hr] in those advised to apply aspirin paste compared with 2 hr (IQR: 0-10 hr) in those that only applied ice (p = 0.04). CONCLUSIONS: Topical aspirin paste was not effective in reducing the duration of swelling or pain in bee and wasp stings, and significantly increased the duration of redness. Symptoms rapidly subsided with ice alone as treatment.

Administration, Topical↗
PubMed2003

Effects of envenoming by comb-footed spiders of the genera Steatoda and Achaearanea (family Theridiidae: Araneae) in Australia.

BACKGROUND: The family Theridiidae (comb-footed spiders) contains the well-known and medically important widow spider group (Latrodectus spp.). Little is known about the effects of envenoming by other common members of this family. OBJECTIVE: The objective of this study was to determine the clinical effects of bites by common theridiid spiders of the genera Steatoda and Achaearanea. METHODS: This was a prospective cohort study of calls to Australian poison information centers and presentations to emergency departments. Twenty-eight persons with a definite bite by a spider of the family Theridiidae, excluding Latrodectus spp., were included where the spider was immediately collected and expertly identified from February 1999 to April 2002. RESULTS: There were 23 bites by Steatoda spp. and five bites by Achaearanea spp. Steatoda bites occurred across Australia, throughout the year, and the majority during waking hours. Seventy-eight percent of bites occurred indoors and 48% while dressing indoors. Pain was universal and was severe in six (26%). Increasing pain in the first hour occurred in 30%, and the median duration of pain was 6 hr (interquartile range: 1-12 hr). Local or regional diaphoresis did not occur. Systemic effects occurred in 30% and included nausea, headache, lethargy, and malaise. The majority received no treatment: seven patients presented to a hospital (two patients received opiates for analgesia) and 1 patient inadvertently received intravenous redback spider (RBS) antivenom because the spider was initially misidentified as a RBS (Latrodectus). The pain and symptoms responded over 1 hr following antivenom administration. Bites by Achaeranea spp. caused moderate to severe persistent pain, but no systemic effects. CONCLUSIONS: Steatoda spp. bites or "steatodism" may cause prolonged pain and systemic effects similar to Latrodectus bites, but less severe. In severe cases, the clinical effects were almost indistinguishable from Latrodectus, except diaphoresis was absent, and the spiders were often mistaken for Latrodectus. Intravenous RBS antivenom appears to be an effective treatment in isolated severe cases, consistent with in vitro work. Achaearanea bites caused pain similar to Latrodectus bites.

Animals↗
PubMed2003

Intentional warfarin overdose.

Warfarin toxicity is common and usually results from dose changes or drug interactions. There are few reported cases of intentional overdose. The management of warfarin overdose is usually complicated by the patient using warfarin therapeutically, often for a mechanical heart valve or pulmonary embolus prophylaxis. Untreated patients have a significant bleeding risk, but treatment carries a significant risk of complete reversal of anticoagulation and consequent risk of thrombosis. The objective of this study was to describe warfarin overdoses and complications of treatment and develop a safe approach to management. Three patients are described. Two patients received a single 10-mg dose of vitamin K. Both required anticoagulation, and in one, warfarin resistance persisted for 2 weeks. In a third patient serial INR, factor levels and warfarin concentrations were measured, and incremental doses of vitamin K (up to 7.5 mg) were given based on INR. This patient did not require anticoagulation, and regular warfarin therapy was recommenced after 4 days. Patients intentionally overdosing on warfarin can be classified into three groups based on preexisting indications for warfarin: nontherapeutic, moderate risk, and major risk for thromboembolic complications. All patients should have regular INR measurements (6-hourly) to catch rapid rises. Patients not on warfarin therapeutically can be given 10 mg of vitamin K1 and repeat INRs as an outpatient. Titrating intravenous vitamin K with doses of 0.5 to 2.0 mg when INR > 5 is appropriate to reduce INR without causing warfarin resistance. The high-risk group must be kept anticoagulated, and warfarin resistance avoided.

Adult↗
PubMed2002

Paracetamol recall: a natural experiment influencing analgesic poisoning.

OBJECTIVES: To determine whether the occurrence of paracetamol and non-paracetamol analgesic deliberate self-poisoning (DSP) and accidental paediatric poisoning was affected by two periods of recall of paracetamol products. DESIGN: Retrospective, observational audit of proportions of poisonings with tablet and capsule formulations of paracetamol, ibuprofen and aspirin products during two recall periods compared with the number of poisonings during the same periods of the previous three years. SETTING: A national poisons information centre and a regional toxicology service. MAIN OUTCOME MEASURES: Rates of DSP and accidental paediatric poisoning with paracetamol, ibuprofen and aspirin. RESULTS: During the two recall periods, there was a significant increase in ibuprofen DSP calls to the poisons information centre (RR, 1.86; 95% Cl, 1.41-2.44; P = 0.001). There was no significant change in paracetamol or aspirin DSP calls over the two recall periods. However, there was a non-significant reduction in DSP calls with paracetamol in the first recall period alone (P = 0.057). There was a significant increase in the proportion of aspirin DSP presentations for the toxicology service (RR, 3.33; 95% CI, 0.97-11.4; P = 0.043), but no significant changes in paracetamol and ibuprofen DSP presentations. For accidental paediatric ingestions there was a significant increase in the proportion of ibuprofen calls (RR, 2.35; 95% CI, 1.85-2.98; P = 0.001), but no significant change in paracetamol or aspirin calls. CONCLUSIONS: Reduced paracetamol availability increased poisoning with alternative analgesics, but had little effect on the incidence of paracetamol poisoning. Restriction of paracetamol-containing products may inadvertently increase poisoning with potentially more toxic agents.

Acetaminophen↗
PubMed2002

Two cases of bites by the black-bellied swamp snake (Hemiaspis signata).

We report two cases of envenomation by the black bellied swamp snake, Hemiaspis signata, with expert identification of the snakes. In the first case a 12 year old boy, who after the removal of the pressure immobilisation bandage, developed decreased fibrinogen levels and positive cross-linked fibrinogen degradation products (XDPs), but normal prothrombin time and activated partial prothrombin time. These changes resolved over 8h with no treatment. In the second case a 7 year old boy had local pain, swelling and axillary lymphadenopathy following the bite. These cases indicate the potential for coagulopathy and local symptoms following bites by large specimens of H. signata in young children.

Animals↗
PubMed2002

Acute allergic reaction following contact with a spider.

Allergic reactions following contact or injury from arachnids are uncommon. There have previously only been reports of urticarial reactions following contact with large spiders from the family Theraphosidae. A 55-year-old male presented to hospital with a generalised urticarial rash following contact with a spider, identified by the person as a huntsman spider (Family: Sparassidae). The spider had crawled over both his arms for a period of minutes. About 30 min later, he developed a rash on the arms which spread to the trunk. He then developed bradycardia and hypotension that required treatment with atropine, adrenaline and histamine antagonists. He recovered within 6 h and had no further problems. The early allergic reaction in this case was most likely the result of contact with the spider.

Animals↗
PubMed2002

Failure of intramuscular antivenom in Red-back spider envenoming.

Four cases of Red-back spider envenoming are reported in which there was minimal response to intramuscular antivenom. Intravenous antivenom was then administered in each case with almost complete resolution of symptoms. All cases were followed up to confirm the effect of treatment. This failure of intramuscular Red-back antivenom raises the question of its efficacy. There has been no controlled trial to prove that intramuscular Red-back antivenom is effective and animal work with other antivenoms has demonstrated the intramuscular formulation to have delayed and incomplete effects. Controlled studies should be undertaken to establish the effectiveness of intravenous and intramuscular Red-back antivenom.

Adult↗