Andrew Macnab

Effect of helmet wear on the incidence of head/face and cervical spine injuries in young skiers and snowboarders

Purpose: To evaluate whether helmets increase the incidence and/or severity of cervical spine injury; decrease the incidence of head injury; and/or increase the incidence of collisions (as a reflection of adverse effects on peripheral vision and/or auditory acuity) among young skiers and snowboarders. Methods: During one ski season (1998–99) at a world class ski resort, all young skiers and snowboarders (<13 years of age) presenting with head, face, or neck injury to the one central medical facility at the base of the mountain were identified. On presentation to the clinic, subjects or their parents completed a questionnaire reviewing their use of helmets and circumstances surrounding the injury event. Physicians documented the site and severity of injury, investigations, and disposition of each patient. Concurrently, counts were made at the entry to the ski area of the number of skiers and snowboarders wearing helmets. Results: Seventy children were evaluated at the clinic following ski/snowboard related head, neck, and face injuries. Fourteen did not require investigation or treatment. Of the remaining 56, 17 (30%) were wearing helmets and 39 (70%) were not. No serious neck injury occurred in either group. Using helmet-use data from the hill, among those under 13 years of age, failure to wear a helmet increased the risk of head, neck, or face injury (relative risk (RR) 2.24, 95% confidence interval (CI) 1.23 to 4.12). When corrected for activity, RR was 1.77 and 95% CI 0.98 to 3.19. There was no significant difference in the odds ratio for collisions. The two groups may have been different in terms of various relevant characteristics not evaluated. No separate analysis of catastrophic injuries was possible. Conclusion: This study suggests that, in skiers and snowboarders under 13 years of age, helmet use does not increase the incidence of cervical spine injury and does reduce the incidence of head injury requiring investigation and/or treatment.

A new system for sternal intraosseous infusion in adults

Background. Intraosseous (IO) infusion provides an alternative route for the administration of fluids and medications when difficulty with peripheral or central lines is encountered during resuscitation of critically ill and injured patients. Objective. To report the first 50 uses of a new system for emergency IO infusion into the sternum in adults, the Pyng F.A.S.T.1 IO infusion system. Methods. Six emergency departments and five prehospital emergency medical services (EMS) sites in Canada and the United States provided clinical and/or research data on their use of the IO system in a pilot study of success rates, insertion times, and complications. Indications for use included adult patient, urgent need for fluids or medications, and unacceptable delay or inability to achieve standard vascular access. A basic data set was standardized for all sites, and some sites collected additional data. Results. The overall success rate for achieving vascular access with the system was 84%. Success rates were 74% for first-time users, and 95% for experienced users. Failure to achieve vascular access occurred most frequently in patients (5 of 9) described subjectively by the user as “very obese,” in whom there was a thick layer of tissue overlying the sternum. Mean time to achieve vascular access was 77 seconds. Flow rates of up to 80 mL/min were reported for gravity drip, and more than 150 mL/min by syringe bolus. Pressure cuffs were also used successfully, although fluid rate was controlled by clamping the line. Further research on flow rates is needed. No complications or complaints were reported at two-month follow-up. Conclusion. These early data indicate that sternal IO infusion using the new F.A.S.T.1 IO system may provide rapid, safe vascular access and may be a useful technique for reducing unacceptable delays in the provision of emergency treatment.

A research tool for measurement of recovery from sedation: The vancouver sedative recovery scale

The need for a research tool to measure recovery from sedation was identified during the design phase of a study investigating sedative protocols following open heart surgery in children. A thorough review of the literature failed to show any scales that measure degree of sedation in children at various times after initial awakening. The Vancouver Sedative Recovery Scale (VSRS) was developed through an iterative process during which we identified numerous indicators of levels of alertness among sedated children, and then determined the applicability and face validity of these indicators. The VSRS evaluated in this study consists of 12 distinct items that encompass three categories of indicators (response; eye appearance and function; and body movement). Total possible VSRS scoring ranges from 0 to 22 (higher score indicating more alert) because some of the 12 items have more than two rating levels. The VSRS was administered to 82 pediatric intensive care unit and postanesthesia recovery patients, with each patient assessed simultaneously by at least two observers. Internal consistency as measured by Cronbachs alpha was excellent: 0.85. Interobserver agreement or reliability as measured by intraclass correlation was also very high: 0.90; and for individual items Cohens kappa ranged from 0.65 to 0.89. We consider the VSRS to be a good beginning in our effort to quantify level of alertness after sedation in the pediatric patient population.

Ingestion of cannabis: a cause of coma in children.

Previous reports of accidental ingestion of cannabis by children are rare. None has reported coma, although one described a stuporous state that required assisted ventilation. Over the past four years, the staff of British Columbias Childrens Hospital has managed six children with cannabis toxicity, three of whom presented in coma, including one with airway obstruction. Recurring diagnostic features included rapid onset of drowsiness, moderate pupil dilation, hypotonia, lid lag, and the presence of small granules or leaves in the mouth. Confirmation was obtained by positive urine screening for cannabinoids. The six cases described emphasize the need for emergency physician awareness of possible diagnostic criteria, the potential severity of intoxication, and the need for prevention through parent education.

Thiamine, riboflavin, and pyridoxine deficiencies in a population of critically ill children

The unexpected autopsy finding of Wernicke encephalopathy in three children who died after prolonged enteral feeding prompted us to examine the incidence of thiamine deficiency in three high-risk pediatric populations. We also measured riboflavin and pyridoxine activity in the same groups. We used activated enzyme assays (erythrocyte transketolase, glutathione reductase, aspartate aminotransferase) to assess tissue stores of the dependent vitamin cofactors (thiamine (vitamin B1), riboflavin (vitamin B2), and pyridoxine (vitamin B6), respectively). Using our own reference ranges based on data from 80 healthy adults and children, we prospectively investigated the B vitamin status of three groups of children: (1) 27 patients who were fed solely by nasogastric tube for more than 6 months, (2) 80 children admitted to a pediatric intensive care unit for more than 2 weeks, and (3) 6 children receiving intensive chemotherapy. The upper limits for stimulated enzyme activity in control subjects were unaffected by age or gender (16% for transketolase, 63% for glutathione reductase, 123% for aspartate aminotransferase). Using these limits, 10 (12.5%) of 80 patients receiving intensive care and 4 of 6 patients receiving chemotherapy were thiamine deficient. Elevated levels returned to normal after thiamine supplementation. No patients were pyridoxine deficient, but 3 (3.8%) of the 80 patients receiving intensive care and 1 of the 6 patients receiving chemotherapy were also riboflavin deficient. We conclude that unrecognized thiamine deficiency is common in our pediatric intensive care and oncology groups. This potentially fatal but treatable disease can occur in malnourished patients of any age and is probably underdiagnosed among chronically ill children. Our findings may be applicable to other high-risk pediatric groups.

Near infrared spectroscopy for intraoperative monitoring of the spinal cord.

Study Design. Animal model study of three healthy commercial pigs was conducted. Objective. To determine whether near infrared spectroscopic monitoring of the spinal cord is feasible, and whether changes in near infrared spectroscopy correlate with changes in blood flow to the cord or operative maneuvers. Summary of Background Data. Near infrared spectroscopy is a noninvasive continuous monitoring tool capable of measuring absolute changes in the concentration of three chromophores: oxygenated hemoglobin, deoxygenated hemoglobin, and cytochrome aa3, the terminal enzyme in the electron transfer chain and a measure of cellular energy equilibrium. Near infrared spectroscopy has been used to monitor the brain intraoperatively in multiple circumstances. The authors hypothesized that near infrared spectroscopy could be used to monitor the spinal cord’s cellular energy equilibrium during spinal surgery (i.e., that vascular compromise could be identified before irreversible damage occurred). Methods. The posterior elements of the spine were exposed, and near infrared spectroscopy optodes (fiberoptic bundles) were sutured to either the lamina or the spinous processes of T9, T10, or both and directed toward the spinal cord. Interventions included manipulation of oxygen saturation and distraction of the T9–T10 disc space. Results. With reduced oxygen delivery (lower arterial oxygen saturation and blood flow), oxygenated hemoglobin concentration decreased and deoxygenated hemoglobin concentration increased. With distraction, blood volume (oxygenated hemoglobin plus deoxygenated hemoglobin) decreased, and cytochrome aa3 became more oxidized. Changes were apparent within 1 second of the intervention beginning, and recovery to the baseline of near infrared spectroscopy occurred with relief of each intervention. Conclusions. This near infrared spectroscopy technique monitors changes in oxygenation of the spinal cord, and therefore appears capable of intraoperative warning about impending vascular compromise of the spinal cord.

The status of pelvic floor muscle training for women

There is no consensus on the amount of exercise necessary to improve pelvic floor muscle (PFM) function. We reviewed the pathophysiology of PFM dysfunction and the evolution of PFM training regimens since Kegel introduced the concept of pelvic floor awareness and the benefits of strength. This paper also describes the similarities and differences between PFM and other muscular groups, reviews the physiology of muscle contraction and principles of muscle fitness and exercise benefits and presents the range of protocols designed to strengthen the PFM and improve function. We also discuss the potential application of new technology and methodologies. The design of PFM training logically requires multiple factors to be considered in each patient. Research that defines measures to objectively quantify the degree of dysfunction and the efficacy of training would be beneficial. The application of new technologies may help this process.

Classification of Male Lower Urinary Tract Symptoms Using Mathematical Modelling and a Regression Tree Algorithm of Noninvasive Near-Infrared Spectroscopy Parameters

BACKGROUND Assessment of bladder outlet obstruction (BOO) is standard clinical practice in patients with lower urinary tract symptoms (LUTS). This is currently achieved through pressure-flow studies. Research indicates that progressive functional impairment of the bladder due to BOO is associated with haemodynamic changes. Near-infrared spectroscopy (NIRS) is an optical method of monitoring tissue oxygenation and haemodynamics via changes in concentration of the chromophores oxyhaemoglobin (O(2)Hb) and deoxyhaemoglobin (HHb). OBJECTIVE To report a noninvasive technique and mathematic method of analysis for assessment of BOO in male subjects using NIRS and to test the independent ability of NIRS data to distinguish between patients with and without obstruction using a classification and regression tree algorithm (CART). DESIGN, SETTING, AND PARTICIPANTS A prospective cohort study to evaluate subjects presenting for urodynamic assessment of LUTS using standard urodynamic studies with simultaneous transcutaneous NIRS monitoring. The NIRS data (magnitude and pattern of changes in O(2)Hb and HHb) were analysed, and a CART algorithm was constructed. Sixty-four males referred for evaluation of LUTS were studied at a tertiary care, university-based research and clinical facility. MEASUREMENTS Clinical symptoms were classified using the International Prostate Symptom Score (IPSS). Pressure-flow studies were done with simultaneous transcutaneous NIRS monitoring of the detrusor. Pressure-flow studies were classified according to the Abrams-Griffiths nomogram. NIRS data documented changes in the concentration of the chromophores O(2)Hb and HHb. RESULTS AND LIMITATIONS IPSS scores ranged from 12 to 34, with a mean of 19. The pressure-flow nomogram found 30 patients with BOO, 16 patients without BOO, and 18 patients with equivocal results. The CART found a misclassification error of 4% with 88% specificity and 94% precision. The NIRS instrument and algorithm were new; no asymptomatic subjects were studied. CONCLUSION Using a CART algorithm, noninvasive NIRS data during voiding had independent discriminatory ability related to classification of BOO.

Health promoting schools: consensus, strategies, and potential

Purpose – The purpose of this paper is to summarize a consensus statement generated on the current challenges, strategies, and potential of health promoting schools (HPS) at a 2011 colloquium at the Stellenbosch Institute for Advanced Study where 40 people from five continents came together to share their global and regional experience surrounding the World Health Organization (WHO) HPS model. Design/methodology/approach – Using the consensus as its foundation, this review summarizes the underlying educational and social science concepts and factors that contribute to success or failure of HPS, and incorporates peer reviewed papers based on invited presentations at the colloquium and key related literature. Findings – HPS increase knowledge and develop behaviors that benefit the health of children, such schools are also an investment in the well-being of the larger community. Importantly for their long-term psychological health “resilience” is generated by effective HPS programs. Professional development ...

Asphyxial games or "the choking game": a potentially fatal risk behaviour

Objectives: To determine the prevalence of knowledge about and participation in asphyxial games, sometimes called “the choking game”, and how best to raise awareness of this risk-taking behaviour and provide preventive education. Design: Questionnaire; collaborative research model; lay advocacy group/university researchers. Setting: 8 middle and high schools in Texas (six) and Ontario (two). A recent death from playing the choking game had occurred in one Texas school, and two other fatalities had occurred within the state. Subjects: Students in grades 4–12, aged 9–18 years. Intervention: None. Outcome measures: None. Results: Of 2762 surveys distributed, 2504 (90.7%) were completed. The mean (SD) age of the responders was 13.7 (2.2) years. 68% of children had heard about the game, 45% knew somebody who played it, and 6.6% had tried it, 93.9% of those with someone else. Forty percent of children perceived no risk. Information that playing the game could result in death or brain damage was reported as most likely to influence behaviour. The most respected source of a preventive education message was parents for pre-adolescents (43%) or victim/victim’s family (36%) for older adolescents. Conclusions: Knowledge of and participation in self-asphyxial behaviour is not unusual among schoolchildren. The age of the child probably determines the best source (parents or victim/victim’s family) of preventive education.