High-'n'-dry? A comparison of cannabis and alcohol use in drivers presenting to hospital after a vehicular collision.

DESIGN: This was a prospective observational study. BACKGROUND AND AIMS: The characteristics of cannabis-involved motor vehicle collisions are poorly understood. This study of injured drivers identifies demographic and collision characteristics associated with high tetrahydrocannabinol (THC) concentrations. SETTING: The study was conducted in 15 Canadian trauma centres between January 2018 and December 2021. CASES: The cases (n = 6956) comprised injured drivers who required blood testing as part of routine trauma care. MEASUREMENTS: We quantified whole blood THC and blood alcohol concentration (BAC) and recorded driver sex, age and postal code, time of crash, crash type and injury severity. We defined three driver groups: high THC (THC ≥ 5 ng/ml and BAC = 0), high alcohol (BAC ≥ 0.08% and THC = 0) and THC/BAC-negative (THC = 0 = BAC). We used logistic regression techniques to identify factors associated with group membership. FINDINGS: Most injured drivers (70.2%) were THC/BAC-negative; 1274 (18.3%) had THC > 0, including 186 (2.7%) in the high THC group; 1161 (16.7%) had BAC > 0, including 606 (8.7%) in the high BAC group. Males and drivers aged less than 45 years had higher adjusted odds of being in the high THC group (versus the THC/BAC-negative group). Importantly, 4.6% of drivers aged less than 19 years had THC ≥ 5 ng/ml, and drivers aged less than 19 years had higher unadjusted odds of being in the high THC group than drivers aged 45-54 years. Males, drivers aged 19-44 years, rural drivers, seriously injured drivers and drivers injured in single-vehicle, night-time or weekend collisions had higher adjusted odds ratios (aORs) for being in the high alcohol group (versus THC/BAC-negative). Drivers aged less than 35 or more than 65 years and drivers involved in multi-vehicle, daytime or weekday collisions had higher adjusted odds for being in the high THC group (versus the high BAC group). CONCLUSIONS: In Canada, risk factors for cannabis-related motor vehicle collisions appear to differ from those for alcohol-related motor vehicle collisions. The collision factors associated with alcohol (single-vehicle, night-time, weekend, rural, serious injury) are not associated with cannabis-related collisions. Demographic factors (young drivers, male drivers) are associated with both alcohol and cannabis-related collisions, but are more strongly associated with cannabis-related collisions.

Correlation between oral fluid and blood THC concentration: A systematic review and discussion of policy implications.

Cannabis is the second most commonly used impairing substance by drivers, after alcohol. As more countries legalize cannabis, there is concern that cannabis-impaired driving will increase. In many countries, police use roadside devices to test for oral fluid THC (the primary psychotropic component in cannabis) to identify drivers who used cannabis; including in countries with non-zero per se limits for THC in blood. This practice is questioned as previous research demonstrates a poor correlation between oral fluid and blood THC concentrations at the individual level. We conducted a meta-analysis to identify all research that compared oral fluid with blood THC levels. We obtained individual-level data from study authors and analyzed pooled individual-level data to calculate sensitivity and specificity of oral fluid THC (at various cut-off values) to detect blood THC above different concentration limits. Finally, we explored practical implications of using oral fluid THC in an enforcement context. Our review found THC concentrations measured in over 18,000 paired samples of oral fluid and blood. We found a good correlation between the presence of THC in oral fluid and presence of THC in blood (sensitivity = 71.2%, specificity = 97.7%). However oral fluid THC, at commonly used cut-off values, is less sensitive and less specific when used as a biomarker to detect people with blood THC concentrations above commonly used per se limits (such as 5 ng/mL). As such, there will be a large number of "false positive" tests if oral fluid THC testing were used as a biomarker for "illegal" THC concentrations in randomly selected drivers. We argue that the adverse implications of false positive oral fluid THC tests in this context outweigh the possible road safety benefits and we recommend against oral fluid THC screening in randomly selected drivers in countries with non-zero per se limits for blood THC. In contrast, oral fluid THC tests appear to be useful for investigating "high-risk" drivers who come to police attention because of evidence of impairment.

Skiing and snowboarding head injury: A retrospective centre-based study and implications for helmet test standards.

BACKGROUND: Head injury occurs in up to 47% of skiing or snowboarding injuries and is the predominant cause of death in these sports. In most existing literature reporting injury type and prevalence, head injury mechanisms are underreported. Thus, protective equipment design relies on safety evaluation test protocols that are likely oversimplified. This study aims to characterize severity and mechanism of head injuries suffered while skiing and snowboarding in a form appropriate to supplement existing helmet evaluation methods. METHODS: A 6-year, multicentre, retrospective clinical record review used emergency databases from two major trauma centres and Coroner's reports to identify relevant cases which indicated head impact. Records were investigated to understand the relationships between helmet use, injury type and severity, and injury mechanism. Descriptive statistics and odds ratios aided interpretation of the data. FINDINGS: The snow sport head injury database included 766 cases. "Simple fall", "jump impact" and "impact with object" were the most common injury mechanisms while concussion was observed to be the most common injury type. Compared to "edge catch", moderate or serious head injury was more common for "fall from height" (OR = 4.69; 95% CI = 1.44-16.23; P = 0.05), "jump impact" (OR = 3.18; 95% CI = 1.48-7.26; P = 0.01) and "impact with object" (OR = 2.44; 95% CI = 1.14-5.56; P = 0.05). Occipital head impact was associated with increased odds of concussion (OR = 7.46; 95% CI = 4.55-12.56; P = 0.001). INTERPRETATION: Snow sport head injury mechanisms are complex and cannot be represented through a single impact scenario. By relating clinical data to injury mechanism, improved evaluation methods for protective measures and ultimately better protection can be achieved.

Efficacy of Wyeth polyvalent antivenin used in the pretreatment of copperhead envenomation in mice.

OBJECTIVES: Wyeth polyvalent crotalid antivenin is the only commercial antivenin available in the United States to treat North American crotalid envenomations. Wyeth antivenin is made from the serum of horses hyperimmunized with four crotalid venoms (Crotalus adamanteus, Crotalus atrox, Crotalus durrisus terrificus, and Bothrops atrox). Although Wyeth antivenin is believed to be effective against all North American crotalids, its efficacy against Agkistrodon contortrix (copperhead) has never been tested. The purpose of this experiment was to determine the efficacy of Wyeth antivenin in the treatment of copperhead envenomation. METHODS: Wyeth antivenin was reconstituted in 10 mL of sterile water. In preliminary experiments, 20 mL/kg of Wyeth antivenin administered intraperitoneally prevented death in mice given a lethal subcutaneous injection of Crotalus adamanteus venom. Freeze-dried copperhead venom was reconstituted in sterile water, and a dose-lethality curve for subcutaneous venom was constructed using seven groups of 10 mice each. The endpoint was survival at 24 hours. A dose that is lethal in 90% of the animals receiving it (LD90) was estimated from this curve. Thirty mice were randomly given pretreatment with 20 mL/kg Wyeth antivenin administered intraperitoneally or an equal volume of normal saline as a control. Thirty minutes later, all mice received an LD90 subcutaneous injection of copperhead venom. Lethality was determined at 24 hours. RESULTS: Following the injection of copperhead venom, none of the 15 control mice and 14 of 15 treatment mice survived until 24 hours (p < 0.001). CONCLUSION: Wyeth antivenin is effective in treating copperhead envenomation in mice and may therefore be expected to be effective in humans.

Delayed toxicity following ingestion of enteric-coated divalproex sodium (Epival).

Toxicity occurs rapidly after overdose with regular-release valproic acid, but there is less experience with enteric-coated formulations. We report a case of delayed onset of toxicity and time to peak levels after ingestion of enteric-coated divalproex sodium (Epival). The patient was a 24-year-old female who ingested an unknown amount of Epival together with ibuprofen, dimenhydrinate, and ethanol. Ninety minutes after ingestion, the patient had only mild toxicity, and valproic acid was undetectable in her blood. By 13 h post-ingestion, valproate levels were 7450 micromol/L (1,075 mg/L), and the patient was comatose and required endotracheal intubation and mechanical ventilation. The toxicity and pharmacokinetics of valproic acid are discussed in the context of this case, and management guidelines are proposed.

Efficacy of digoxin specific Fab fragments (Digibind) in the treatment of toad venom poisoning.

Chan Su, a traditional Chinese medication, and Love Stone, a topical aphrodisiac, are both made from dried venom of the toad bufo bufo gargarizans and contain bufalin, cinobufotalin, cinobufagin, and other cardioactive steroids of the bufadienolide class. Deaths have occurred following ingestion of these products and the clinical course resembles digoxin toxicity. The purpose of this study was to determine the efficacy of digoxin specific Fab fragments in treating Chan Su poisoning. An ethanolic extract was prepared from Chan Su. Digoxin specific Fab fragments were reconstituted in normal saline to a concentration of 80 mg/ml. An approximate LD90 dose was determined in preliminary experiments. Mice were then randomly divided into a treatment group of 15 mice and a control group of 30 mice. The treatment group was pretreated with 20 ml/kg of digoxin specific Fab fragment solution by intraperitoneal injection at t = 0, followed by 10 ml/kg of digoxin specific Fab fragments intraperitoneal at t = 30 min. The control group was pretreated with equal volumes of intraperitoneal normal saline at the same times. Immediately following the 30 min injection, both groups were given the estimated LD90 dose of Chan Su extract by subcutaneous injection. An endpoint of survival at 6 h was chosen after preliminary results showed that all deaths occurred in the first 4 h. All 30 of the control mice had seizures followed by death compared to 11 seizures and 7deaths in the 15 treatment mice. These results were statistically significant by Fisher's exact test (p = 0.00003 for mortality and p = 0.009 for seizures). Digoxin specific Fab fragments are effective in the treatment of Chan Su poisoning in mice and may be effective for poisoning by other cardioactive steroids of the bufadienolide class.

Treatment of toad venom poisoning with digoxin-specific Fab fragments.

Toxicity from toad venom poisoning is similar to digoxin toxicity and carries a high mortality rate. We report on six previously healthy men who developed vomiting and bradycardia after ingesting a purported topical aphrodisiac. Each patient had positive apparent digoxin levels and the first four patients died of cardiac dysrhythmias. The last two patients recovered following treatment with digoxin Fab fragments. We analyzed samples of the purported aphrodisiac and found that it was identical to Chan Su, a Chinese medication made from toad venom. To our knowledge, this is the first reported use of digoxin Fab fragments to treat toad venom poisoning.

Serotonin syndrome from venlafaxine-tranylcypromine interaction.

Excessive stimulation of serotonin 5HT1A receptors causes a syndrome of serotonin excess that consists of shivering, muscle rigidity, salivation, confusion, agitation and hyperthermia. The most common cause of this syndrome is an interaction between a monoamine oxidase inhibitor (MAOI) and a specific serotonin reuptake inhibitor. Venlafaxine is a new antidepressant agent that inhibits the reuptake of serotonin and norepinephrine. We report a venlafaxine-MAOI interaction that resulted in the serotonin syndrome in a 23-y-old male who was taking tranylcypromine for depression. He had been well until the morning of presentation when he took 1/2 tab of venlafaxine. Within 2 h he became confused with jerking movements of his extremities, tremors and rigidity. He was brought directly to a hospital where he was found to be agitated and confused with shivering, myoclonic jerks, rigidity, salivation and diaphoresis. His pupils were 7 mm and sluggishly reactive to light. Vital signs were: blood pressure 120/67 mm Hg, heart rate 127/min, respiratory rate 28/min, and temperature 97 F. After 180 mg of diazepam i.v. he remained tremulous with muscle rigidity and clenched jaws. He was intubated for airway protection and because of hypoventilation, and was paralyzed to control muscle rigidity. His subsequent course was remarkable for non-immune thrombocytopenia which resolved. The patient's maximal temperature was 101.2 F and his CPK remained < 500 units/L with no other evidence of rhabdomyolysis. His mental status normalized and he was transferred to a psychiatry ward. This patient survived without sequelae due to the aggressive sedation and neuromuscular paralysis.

Intestinal pseudo-obstruction (Ogilvie's syndrome) in theophylline overdose.

Intestinal pseudo-obstruction (Ogilvie's syndrome) has previously been reported in 2 patients with theophylline toxicity treated with activated charcoal (AC), mechanical ventilation and opioid induced sedation. We report a case of Ogilvie's syndrome in a theophylline toxic patient treated with AC. A 45-y-old male with severe chronic obstructive pulmonary disease presented with vomiting and multifocal atrial tachycardia after an intentional theophylline overdose. His initial potassium concentration was 2.7 mEq/L and his theophylline was 191 mg/L (1060 mumol/L). The patient was hemodialyzed and given a total of 1,000 g of AC without cathartics during the first hospital day. He also received iv potassium replacement. On the second hospital day he required mechanical ventilation for respiratory acidosis. Clindamycin was given for purulent sputum and fever. Haloperidol was given to treat agitation. No other anticholinergic agents or opioids were given. The patient's potassium rose to 6.5 mEq/L and he was given kayexalate. During the third hospital day the patient developed abdominal distention, tenderness and leukocytosis. Abdominal radiographs revealed a distended cecum. In the operating room the cecum was found dilated to 16 cm with no distal obstruction. A cecostomy tube drained AC and pill fragments. A 6 cm charcoal bezoar was found in the stomach. The patient recovered uneventfully.

Salicylism from topical salicylates: review of the literature.

BACKGROUND: Although topical salicylates are widely used, toxicity from this route is rare. CASE REPORT: We present an unusual case of salicylism from a topical salicylate preparation in an 80-year-old woman. The patient was admitted to the dermatology service with a diagnosis of erythroderma and was treated with salicylate containing ointments. After six days of treatment the patient became confused and paranoid. A serum salicylate was 3.36 mmol/L (46 mg/dL). The patient was admitted to the intensive care unit were she was rehydrated and treated with bicarbonate and activated charcoal. RESULTS: Her serum salicylate fell to 1.90 mmol/L (26 mg/dL) over a two day period and she regained a normal mental status.