Daniel Cass

The Canadian CT Head Rule for patients with minor head injury

BACKGROUND There is much controversy about the use of computed tomography (CT) for patients with minor head injury. We aimed to develop a highly sensitive clinical decision rule for use of CT in patients with minor head injuries. METHODS We carried out this prospective cohort study in the emergency departments of ten large Canadian hospitals and included consecutive adults who presented with a Glasgow Coma Scale (GCS) score of 13-15 after head injury. We did standardised clinical assessments before the CT scan. The main outcome measures were need for neurological intervention and clinically important brain injury on CT. FINDINGS The 3121 patients had the following characteristics: mean age 38.7 years); GCS scores of 13 (3.5%), 14 (16.7%), 15 (79.8%); 8% had clinically important brain injury; and 1% required neurological intervention. We derived a CT head rule which consists of five high-risk factors (failure to reach GCS of 15 within 2 h, suspected open skull fracture, any sign of basal skull fracture, vomiting >2 episodes, or age >65 years) and two additional medium-risk factors (amnesia before impact >30 min and dangerous mechanism of injury). The high-risk factors were 100% sensitive (95% CI 92-100%) for predicting need for neurological intervention, and would require only 32% of patients to undergo CT. The medium-risk factors were 98.4% sensitive (95% CI 96-99%) and 49.6% specific for predicting clinically important brain injury, and would require only 54% of patients to undergo CT. INTERPRETATION We have developed the Canadian CT Head Rule, a highly sensitive decision rule for use of CT. This rule has the potential to significantly standardise and improve the emergency management of patients with minor head injury.

Platelet-activating factor, PAF acetylhydrolase, and severe anaphylaxis.

BACKGROUND Platelet-activating factor (PAF) is an important mediator of anaphylaxis in animals, and interventions that block PAF prevent fatal anaphylaxis. The roles of PAF and PAF acetylhydrolase, the enzyme that inactivates PAF, in anaphylaxis in humans have not been reported. METHODS We measured serum PAF levels and PAF acetylhydrolase activity in 41 patients with anaphylaxis and in 23 control patients. Serum PAF acetylhydrolase activity was also measured in 9 patients with peanut allergy who had fatal anaphylaxis and compared with that in 26 nonallergic pediatric control patients, 49 nonallergic adult control patients, 63 children with mild peanut allergy, 24 patients with nonfatal anaphylaxis, 10 children who died of nonanaphylactic causes, 15 children with life-threatening asthma, and 19 children with non-life-threatening asthma. RESULTS Mean (+/-SD) serum PAF levels were significantly higher in patients with anaphylaxis (805+/-595 pg per milliliter) than in patients in the control groups (127+/-104 pg per milliliter, P<0.001 after log transformation) and were correlated with the severity of anaphylaxis. The proportion of subjects with elevated PAF levels increased from 4% in the control groups to 20% in the group with grade 1 anaphylaxis, 71% in the group with grade 2 anaphylaxis, and 100% in the group with grade 3 anaphylaxis (P<0.001). There was an inverse correlation between PAF levels and PAF acetylhydrolase activity (P<0.001). The proportion of patients with low PAF acetylhydrolase values increased with the severity of anaphylaxis (P<0.001 for all comparisons). Serum PAF acetylhydrolase activity was significantly lower in patients with fatal peanut anaphylaxis than in control patients (P values <0.001 for all comparisons). CONCLUSIONS Serum PAF levels were directly correlated and serum PAF acetylhydrolase activity was inversely correlated with the severity of anaphylaxis. PAF acetylhydrolase activity was significantly lower in patients with fatal anaphylactic reactions to peanuts than in patients in any of the control groups. Failure of PAF acetylhydrolase to inactivate PAF may contribute to the severity of anaphylaxis.

Nonuse of bicycle helmets and risk of fatal head injury: a proportional mortality, case–control study

Background: The effectiveness of helmets at preventing cycling fatalities, a leading cause of death among young adults worldwide, is controversial, and safety regulations for cycling vary by jurisdiction. We sought to determine whether nonuse of helmets is associated with an increased risk of fatal head injury. Methods: We used a case–control design involving 129 fatalities using data from a coroner’s review of cycling deaths in Ontario, Canada, between 2006 and 2010. We defined cases as cyclists who died as a result of head injuries; we defined controls as cyclists who died as a result of other injuries. The exposure variable was nonuse of a bicycle helmet. Results: Not wearing a helmet while cycling was associated with an increased risk of dying as a result of sustaining a head injury (adjusted odds ratio [OR] 3.1, 95% confidence interval [CI] 1.3–7.3). We saw the same relationship when we excluded people younger than 18 years from the analysis (adjusted OR 3.5, 95% CI 1.4–8.5) and when we used a more stringent case definition (i.e., only a head injury with no other substantial injuries; adjusted OR 3.6, 95% CI 1.2–10.2). Interpretation: Not wearing a helmet while cycling is associated with an increased risk of sustaining a fatal head injury. Policy changes and educational programs that increase the use of helmets while cycling may prevent deaths.

Canadian C-Spine Rule study for alert and stable trauma patients: I. Background and rationale

This paper is Part I of a 2-part series to describe the background and methodology for the Canadian C-Spine Rule study to develop a clinical decision rule for rational imaging in alert and stable trauma patients. Current use of radiography is inefficient and variable, in part because there has been a lack of evidence-based guidelines to assist emergency physicians. Clinical decision rules are research-based decision-making tools that incorporate 3 or more variables from the history, physical examination or simple tests. The Canadian CT Head and C-Spine (CCC) Study is a large collaborative effort to develop clinical decision rules for the use of CT head in minor head injury and for the use of cervical spine radiography in alert and stable trauma victims. Part I details the background and rationale for the development of the Canadian C-Spine Rule. Part II will describe in detail the objectives and methods of the Canadian C-Spine Rule study.

Potential organ donors referred to Ontario neurosurgical centres

PurposeEleven hospitals in Ontario are adult neurosurgical centres (ONCs). Patients transferred to ONCs from community hospitals with acute intracranial emergencies often have non-survivable injuries, and may be returned to the referring hospital for end-of-life care. These referring hospitals may not be familiar with neurological determination of death, or organ donation. Our objective was to determine the number of patients with severe brain injuries assessed in ONC emergency departments where progression to brain death may be reasonably expected, and to determine their outcome.MethodsA one-year retrospective cohort study was undertaken using a convenience sample of patients transferred to eight ONCs for neurosurgical assessment, with evidence of either (a) brain death in the emergency department, or (b) severe brain injury who met criteria of a reasonable likelihood of progression to brain death. The outcome of these patients to disposition from the ONC was determined by chart review.ResultsThree thousand four hundred and forty-seven patients were identified of whom 141 met inclusion criteria. Eleven patients (7.8%) were pronounced dead in the emergency department, 96 (68.1%) patients were admitted, and 34 (24.1%) were transferred back to their referring hospital. Fourteen patients (9.9%) became organ donors: two died in the emergency department and 12 died following admission.ConclusionsA significant number of patients transferred to ONCs have an injury with a likelihood of progressing to brain death, but only a small proportion of these patients become organ donors. Emergency department triage, assessment and admission decisions for patients with intracranial catastrophes should consider diagnostic criteria for brain death and recognition of donor potential as part of end-of-life care.RésuméObjectifEn Ontario, 11 hôpitaux sont des centres neurochirurgicaux (CNO) pour adultes. Les patients, transférés des hôpitaux communautaires vers les CNO, présentant des lésions intracrâniennes aiguës à traiter d’urgence, souvent ne survivent pas et peuvent être retournés à l’hôpital d’origine pour des soins aux mourants. La détermination de la mort neurologique, ou du don d’organe, n’est peut-être pas familière aux hôpitaux communautaires. Notre objectif était de déterminer le nombre et l’évolution de patients atteints de lésions cérébrales sévères évaluées dans les urgences des CNO où la progression vers une mort encéphalique peut être raisonnablement attendue.MéthodeUne étude rétrospective a été entreprise en utilisant un échantillon de commodité des patients transférés dans huit CNO au cours d’un an, pour une évaluation neurologique qui présentait des signes (a) de mort encéphalique au service d’urgence ou (b) d’une lésion cérébrale sévère qui, selon les critères, allait probablement progresser vers la mort encéphalique. Ľévolution des patients retournés à leur hôpital par le CNO a été faite par l’examen du dossier.RésultatsDes 3 447 patients recensés, 141 répondaient aux critères d’inclusion de l’étude. Onze patients (7,8 %) ont été déclarés morts au service d’urgence, 96 (68,1 %) ont été admis et 34 (24,1 %) retournés à leur hôpital communautaire. Quatorze patients (9,9 %) sont devenus des donneurs d’organes : deux sont morts à l’urgence et douze après l’admission. Conclusion : Un nombre significatif de patients transférés vers les CNO ont une lésion qui va probablement progresser vers la mort encéphalique, mais peu d’entre eux deviennent des donneurs d’organes. Le tri à l’urgence, l’évaluation et l’admission des patients atteints de lésions intracrâniennes catastrophiques doivent comporter les critères diagnostiques de mort encéphalique et l’identification de donneur potentiel comme une partie des soins de fin de vie.