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A J Macnab

Publications and source records attributed to A J Macnab.

At least 19 recordsLinked to original sources
PubMed2006

Illustration of genetic syndromes in the nursery.

Reading to children and storytelling has documented developmental benefits. Traditional Nursery Rhymes (Mother Goose tales in North America) encapsulate 'snapshots' of the people described and chronicle their customs, superstitions, and amusements. Art has long been employed to document the impact of human imperfections and diseases. We investigated whether illustrations accompanying nursery rhymes, suggest that any characters illustrated may have had or been based on recognized morphological abnormalities, and if this literature documents a role for grandmothers as storytellers. Archival materials were reviewed at the Victoria and Albert museum and Mary Evans picture library, and via the web. As early as 1695, Perrault included a frontispiece of a mature woman as storyteller in his book of fairytales. Similar scenes by various artists (Boilly, Cruikshank, Guy, Highmore, Maclise, Richter, and Smith) are found consistently from 1744 to 1908. Many illustrators (Aldin, Caldecott, Cruikshank, Doré, Dulac, Gale, Greenaway, Rackham, Tarrant, and Wood) portray infants, children, and adults who are dwarfed, giant, or whimsically grotesque. Many images certainly suggest genetic syndromes, and in some characters consistency of specific features is evident between artists. Our research confirms the wealth of children's nursery rhyme illustrations suggesting pathology; that an authoritative compilation of the morphologies depicted is lacking; and that historically, grandmothers have a central role as storytellers.

Cartoons as Topic↗
PubMed2006

Correlation of transcutaneous hepatic near-infrared spectroscopy readings with liver surface readings and perfusion parameters in a piglet endotoxemic shock model.

PURPOSE: To determine whether transcutaneous liver near-infrared spectrophotometry (NIRS) measurements correlate with NIRS measurements taken directly from the liver surface, and invasive blood flow measurements. PROCEDURE: Laparotomy was performed in 12 Yorkshire piglets, and ultrasound blood flow probes were placed on the hepatic artery and portal vein. Intravascular catheters were inserted into the hepatic and portal veins for intermittent blood sampling, and a pulmonary artery catheter was inserted via the jugular vein for cardiac output measurements. NIRS optodes were placed on skin overlying the liver and directly across the right hepatic lobe. Endotoxemic shock was induced by continuous infusion of Escherichia coli lipopolysaccharide O55:B5. Pearson's correlations were calculated between the NIRS readings and the perfusion parameters. FINDINGS: After endotoxemic shock induction, liver blood flow, and oxygen delivery decreased significantly. There were statistically significant correlations between the transcutaneous and liver-surface NIRS readings for oxyhemoglobin, deoxyhemoglobin, and cytochrome c oxidase concentrations. There were similar significant correlations of the transcutaneous oxyhemoglobin with both the mixed venous and hepatic vein saturation, and mixed venous and hepatic vein lactate. CONCLUSIONS: Transcutaneous NIRS readings of the liver, in an endotoxemic shock model, correlate with NIRS readings taking directly from the liver surface, as well as with global and specific organ-perfusion parameters.

Animals↗
PubMed2002

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.

Adolescent↗
PubMed2001

An inventory of Canadian anesthesiology. Human research from 1995 through 1999.

PURPOSE: The year 2000 provides a symbolic opportunity to assess the past initiatives in anesthesia research. As in many other fields, medical research has benefited from utilizing computerized data bases to facilitate enumerating areas of interest. We have created a baseline survey of past research in the fields of anesthesia, anesthetics, analgesia, and analgesics to highlight Canadian studies. METHODS: The survey was undertaken using the Medical Literature Analysis and Retrieval System (MEDLARS) medical literature archive for the years 1995 through 1999. The principal categories and sub-categories of MEDLARS' anesthesia classifications were counted for 70 countries contributing to the archive. RESULTS: Canadian contributions ranged from 141 (1992) to 185 (1999) and represented annually 3% of the world total in the anesthesia categories. The greatest number of studies (30-38%) were about adults aged 19 to 44 yr, and there were between 4% and 14% more studies of females than males. "Pharmacology" and "therapeutic use" were the most frequent topics, lidocaine, fentanyl, and propofol were the most studied anesthetics, and non-steroidal anti-inflammatories, opium, morphine, and fentanyl were the most studied analgesics. Among the types of studies, those classified as "quality of health care" occurred most frequently (16%). Canadian trends closely follow world trends. CONCLUSION: The collected counts provide a comprehensive overview of research trends for the past five years.

Adult↗
PubMed2001

Pediatric eye injury due to Avena fatua (wild oats).

OBJECTIVE: We report on florid and unusual ophthalmic physical signs in three children where the trauma was caused by seeds from Avena fatua, a grass common in western North America. DESIGN: Case series and literature review. SETTING: Three local emergency departments (ED) during the fall of 1998. PATIENTS OR PARTICIPANTS: Three children reporting to an ED with an acutely painful eye from which the foreign body was identified botanically as Avena fatua. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Symptoms, interventions, duration of problem. RESULTS: Three male children (6, 10, 14 years) presented separately following incidents in which they had sustained direct eye injury. Each child immediately experienced severe pain and profuse watering of the eye. Severe localized edema of the conjunctiva and inflammation was evident with conjunctival vessel injection leading to bleeding, reminiscent of a chemical "burn." Initially, two children appeared to have an eyelash caught behind the lower lid. In both instances, the emergency physicians initially dismissed the possibility of there being a significant foreign body, but because of the severity of the pain, conjunctival vessel injection, and edema, they attempted to remove the "lash." Removal of the foreign body proved difficult in all three cases, requiring far greater traction than anticipated. Intact seedpods had become embedded in the subconjunctival space. Ophthalmic analgesia relieved the pain immediately, but in one child who was treated with topical antibiotic alone, significant pain was experienced for 18 hours, until steroid-antibiotic therapy was instituted. All injuries occurred in late summer when the grass propagates. CONCLUSIONS: The physical signs of scleral vasculitis and conjunctival edema can be mistaken for chemical injury or allergic chemosis, but where a foreign body resembling a hair or eyelash is visible, the presence of a seed-pod retained in the subconjunctival space must be considered, particularly if the patient reports exposure to wild grass. Application of local analgesia, foreign body removal, and steroid-antibiotic treatment is recommended.

Adolescent↗
PubMed2001

Self strangulation by hanging from cloth towel dispensers in Canadian schools.

OBJECTIVE: To investigate a local "epidemic" of incidents of strangulation by hanging from continuous cloth towels in dispensers. METHOD: The coroner's office in all provinces and territories were contacted. Five cases of hanging from continuous cloth towels in Canadian schools were identified and reviewed. RESULTS: There were four deaths, and one near-death, all males age 7 to 12. Two cases were attributed to a "choking game" that provides a sensation (impending loss of consciousness) described as "cool". In three cases, the child was alone at the time. All deaths were due to strangulation from hanging and all occurred in school washrooms. One child (playing with two friends) recovered after admission to an intensive care unit. Towel dispensers were removed from the two index schools. In one province the Ministry of Education encouraged removal of towel dispensers from all schools and education of students of the dangers of "choking games". CONCLUSIONS: Thrill seeking from partial asphyxiation appears to underlie these incidents. Awareness of such cases should prompt appropriate education strategies to highlight the serious consequences of this form of risk taking behavior in young males. In Canada, these incidents have resulted in changes in the design of, and legislation regarding, cloth towel dispensers.

Asphyxia↗
PubMed2000

A quantitative ranking of Canada's research output of original human studies for the decade 1989 to 1998.

BACKGROUND: Since 1987 research articles have been catalogued with the author's affiliation address in the 40 databases of the Medical Literature Analysis and Retrieval System (MEDLARS) of the National Library of Medicine, Bethesda, Md. The present study was conducted to examine the Canadian entries in MEDLARS to interpret past and future trends and to combine the MEDLARS demographic data with data from other sources to rank Canadian research output of human studies both nationally and internationally. METHODS: The PubMed Web site of the National Library of Medicine was used to count medical articles archived in MEDLARS and published from Jan. 1, 1989, through Dec. 31, 1998. The articles attributed to Canadian authors were compared by country, province, city, medical school, hospital, article type, journal and medical specialty. RESULTS: During the study period Canadian authors contributed on average 3% (standard deviation [SD] 0.2%) of the worldwide MEDLARS content each year, which translated to a mean of 11,067 (SD 1037) articles per year; 49% were human studies, of which 13% were clinical or controlled trials, and 55% involved people aged 18 years or less. In total, 68% of the articles were by authors affiliated with Canadian medical schools; those affiliated with the University of Toronto accounted for the greatest number (8604), whereas authors affiliated with McGill University had the greatest rate of annual increase in the quantity published (8%). Over one-third (38%) of the articles appeared in Canadian journals. When counted by specialty, 17% of the articles were by authors with clinical specialties, 5% by those with surgical specialties and 3% by those with laboratory specialties. INTERPRETATION: The annual rate of increase in research output for Canada was more than 3 times higher than that seen world wide. Canada is now ranked seventh among countries contributing human studies to MEDLARS. The increase indicates that Canada's medical schools are productive, competitive in making contributions to medical science and are supporting Canadian journals.

Canada↗
PubMed2000

Effects of propofol on cerebral oxygenation during cardiopulmonary bypass in children.

PURPOSE: Neurologic complications occur following cardiopulmonary bypass surgery. We conducted a randomized, controlled, single-blind study to determine the effect of propofol on the redox status of cytaa3, and to evaluate its potential for decreasing neurologic complications. METHODS AND MATERIALS: Twenty-four children (median age: 3.3 yr; median weight: 14.4 kg) scheduled for elective cardiopulmonary bypass surgery were assigned to either the experimental group (Group P, given sufficient propofol to eliminate brain electrical activity as measured on EEG (i.e. burst suppression)) or the control group (Group C, no propofol). Near infrared spectroscopy data were collected at one-second intervals throughout the surgical procedures. Pre- and postoperative neurologic examinations were completed by a physician blinded to the group to which the patient was assigned. Change in cytochrome aa3 data at 10-min intervals (10, 20, 30, 40 min) following start of bypass were compared between groups by repeated measures analysis of variance. RESULTS: The patterns of change in redox state of cytochrome were different between the two groups (P < 0.002). The pattern of change within Group P was similar to that in hypothermic patients in Group C. There were correlations between change in cytaa3 redox status and temperature in the control subjects. There were no gross neurologic complications in either group. CONCLUSIONS: Propofol appears to stabilize the energy supply/demand equilibrium of the brain during cardiopulmonary bypass surgery and thus theoretically could reduce the incidence or severity of neurologic complications.

Anesthetics, Intravenous↗
PubMed1999

Family-oriented care during pediatric inter-hospital transport.

We evaluated the family-oriented care and counseling provided by the BC Children's Hospital Transport Team paramedies. One hundred families were asked to rate: (1) how they would like paramedies to communicate with them under ideal conditions; and (2) what they actually experienced during their child's transport. There were no significant differences in parents' preferences under ideal circumstances and what they actually experienced in five of nine behavioural areas studied. Nineteen paramedies also rated their use of elements of family-oriented communication and the strategies they would recommend other teams use when interacting with families. The elements that paramedies reported using most frequently were rated highly by parents and produced positive feelings in the majority of families. The study indicates that effective counseling can be achieved in 'critical', time-limited situations but improvements can be made; and it supports the value of appropriate selection and training of transport team personnel in family-oriented critical care.

Adult↗
PubMed1999

Variations in regional cerebral blood volume in neonates associated with nursery care events.

This pilot study investigated the frequency of events that cause cerebral oxygenation disturbances in ventilator-dependant neonates in the neonatal intensive care unit. Continuous, noninvasive, near infrared spectrophotometry measurements (changes in oxy and deoxy hemoglobin concentration, and cytochrome C oxidase redox status) were made at half-second intervals on 10 ventilator-dependent neonates (30.5 weeks average corrected gestation age, 1051 g average weight) and annotated to nursery events at the bedside. Examples of disturbances affecting cerebral oxygenation were opening incubator doors, handling, heel stabs, conversation, blanket tucking, and steno-paging. These events produced 7-40% changes in blood volume for durations of 5-60 sec, and occurred at a rate of up to 45 events within a 2 hr period. Spectrometry detected 63% more events than were observed and documented clinically. Noninvasive monitoring of cerebral oxygenation status could give new insight into managing the high-risk infant environment.

British Columbia↗
PubMed1999

Teaching pediatric procedures: the Vancouver model for instructing Seldinger's technique of central venous access via the femoral vein.

The way in which physicians are trained to do invasive practical procedures is an ongoing challenge for educators. Percutaneous insertion of a central line via the femoral vein using the Seldinger technique is an important practical pediatric procedure, and the need for physicians to be educated in the necessary skills is recognized in current training initiatives such as Pediatric Advanced Life Support (PALS) and Advanced Pediatric Life Support. Unfortunately, the majority of instruction in central venous access techniques is theoretic. This approach does not provide the hands-on training needed to give practitioners the necessary practical experience, or confidence in their skills. Practice using simulated tissue can enable physicians to perform practical skills with greater confidence. However, although commercially available models exist for peripheral venous access, a recent cross-Canada survey of the 13 PALS program coordinators and a similar inquiry to the American Heart Association indicated that none of them had a pediatric practice model for central venous access. We describe 1) how to construct from materials readily available a pediatric model for the insertion of central venous catheters into the femoral vein using the Seldinger technique, and 2) an evaluation of the change in confidence learning with the model engendered. In our experience, this model is inexpensive (less than $50) and can be replicated readily by others for use as a teaching aid. It provides inexperienced physicians the opportunity to learn the practical elements of the technique and acquire confidence in the Seldinger method. Our hypothesis was that the confidence and skill of physicians would be increased by practical experience of central line insertion using a realistic model. The model enables trainees to be taught the technique described in the PALS manual to locate the femoral artery. They then can learn to introduce a thin-walled needle or over-the-needle catheter, one finger's breadth below the inguinal ligament and just medial to the location of the femoral artery. The needle or over-the-needle catheter then can be advanced at the correct angle if the needle is directed toward the model's umbilicus. As occurs in vivo, the model allows for a free flow of fluid to be obtained as the "vessel" is entered. If the Foley catheter simulating the vessel is transfixed, negative pressure applied as the needle is withdrawn will result in fluid being obtained as the needle tip reenters the "vessel." The syringe then can be removed from the needle, and the key elements of the procedure-correct insertion of the Seldinger guide wire and passage of the venous catheter over the guide wire into the vessel-can be practiced. If desired, instruction also can be given on the use of a dilator and techniques of taping the catheter in place and all the appropriate techniques to avoid potential air embolism. However, the model does not lend itself to instruction in suturing. The model has been used to teach the practical elements of this technique to 428 physicians (emergency physicians, 49%; pediatricians, 24%; other physicians, 20%; pediatric residents, 7%). Their success rate for cannula insertion in three or fewer attempts was 87%. The last 218 physicians were evaluated to assess the influence of learning with the model on their confidence to perform the technique successfully in an emergency. Before training they were asked, "Have you done a pediatric resuscitation course that taught this technique in theory?" and "Rate your confidence level for performing central vascular access in a patient from 0 to 5 (none, very little, some, moderate, good, complete)." This rating was repeated after the training session using the model. For 154 (71%) answering "yes" to a previous resuscitation course, mean scores were 1.52 (standard error [SE] +/- 0.91) after theoretic instruction and 4.06 (SE +/- 0.47) after practical education using our model. The 64 (29%) physicians

Catheterization, Central Venous↗
PubMed1998

Journal writing as a social support strategy for parents of premature infants: a pilot study.

BACKGROUND: Having a premature baby is acknowledged to be stressful to parents. Journal writing combines practical, emotional and informational support that may be useful to these parents. METHODS: We conducted a study to assess the potential for promoting journal-writing for parents receiving social support in a special care nursery (SCN). Parents were provided with educational material on journal writing, and subsequently surveyed concerning their journal-writing during their child's hospitalization. RESULTS: Of the 73 parents enrolled, 32% kept a journal; of these, 73% felt it helped considerably in reducing stress, and 68% used it as a means of addressing the most stressful elements of their nursery experience. Journals were used primarily to document involvement in care (45%), record-keeping (36%), and organization of thoughts (27%). All of those who kept a journal recommended it for use by other parents. CONCLUSIONS: Encouraging parents to keep a journal is a constructive way of dealing with the SCN-related stress.

Adaptation, Psychological↗
PubMed1998

Successful treatment of dinitrophenol poisoning in a child.

BACKGROUND: Poisoning with agricultural toxins is well known in the adult environment, but is rarely seen in children. Vancouver, British Columbia, borders on a large agricultural area, and the British Columbia Children's Hospital is the provincial referral center for major pediatric emergencies. In our experience, children from farming communities are vulnerable to a range of agriculturally related injuries, and exposure to toxic chemicals requiring hospitalization is not rare. METHODS: This is a case report with literature review. RESULTS: A child presenting in a coma proved later to have been exposed to a toxic agent. The agent, dinitrophenol, is a widely used agricultural herbicide and insecticide. The diagnosis resulted from a detailed history and physical examination, which revealed symptoms and signs that suggested poisoning. A search of the farm resulted, and the parents located open dinitrophenol containers. The toxic effects of dinitrophenol described in adults by Poison Control matched those present in the child, and specific treatment interventions existed that could be implemented to positively influence outcome. CONCLUSIONS: Awareness of the possibility of exposure to dinitrophenol is required, as death can result from exposure, and milder cases may go unrecognized. Appropriate treatment can improve outcome. Injuries with toxic agricultural agents are wholly preventable if the materials are handled appropriately in the farm environment, and parents whose children live on or visit farms are aware of the risks involved and take appropriate precautions.

Adult↗
PubMed1997

Midazolam premedication delays recovery after propofol without modifying involuntary movements.

Midazolam has GABAergic effects in children that may modify propofol-induced involuntary movements, yet delay recovery. In a double-blind, randomized study, 24 children (2-7 yr of age, ASA physical status I or II) undergoing short surgical procedures received midazolam 0.5 mg/kg (Group M) or placebo (Group P) per os 20-30 min before propofol anesthesia (5 mg/kg intravenously followed by an infusion). Blind observers scored sedation and anxiety levels (scale 1-4) before premedication, at separation from parents, and at induction of anesthesia. Induction and emergence were videotaped, and body movements were recorded. During recovery, times to eye opening and maximum Steward (SS = 6) and Vancouver Sedative Recovery (VSRS = 22) scores were noted. Parents were questioned about side effects that may have occurred during the following week. Both groups were similar in age, sex, weight, timing of premedication, propofol dose, and duration of surgery. The incidence of involuntary movements did not differ between groups but was higher at induction (79%) than on emergence (25%) (P < 0.05). Anxiety and sedation scores were similar in Group P and Group M, but recovery took longer after midazolam, with eye opening (mean +/- SD) 24 +/- 7 vs 43 +/- 18 min, maximum SS (median and range) 27 (13-37) vs 55 (24-138) min, and maximum VSRS 51 (30-100) vs 80 (50-130) min. Children returned to normal activity in 1 (0-5) day, and none exhibited neurological complications. We conclude that an oral premedicant dose of midazolam prolongs recovery from anesthesia in children without affecting dystonic movements after propofol.

Administration, Oral↗
PubMed1996

Comparison of 13 published cytochrome c oxidase near-infrared spectroscopy algorithms.

Conflicting patterns of change in cytochrome c oxidase (Cyt a,a3) redox status have been obtained between different near-infrared spectrophotometers when making measurements during tissue ischaemia. This study identifies possible sources of error that could be the cause of the discrepancy. A single set of optical density data was repeatedly analysed using each of the absorption spectra from 13 publications. In addition, changes in Cyt a,a3 redox status were calculated from the data set using three numerical methods, five computer software routines, eight displacements in wavelength, and ten incremental changes in the value of absorption or concentration coefficients. All Cyt a,a3 absorption spectra resulted in algorithms yielding similar patterns of change, regardless of the numerical method or computer process employed (0.9996 average r2, coefficient of correlation). However, a significantly different pattern of change in Cyt a,a3 redox status, resembling that reported by Piantadosi [Piantadosi CA (1993) Methods Toxicol. 2:107-126], was obtained when either the wavelengths, and/or the absorption values were altered to simulate erroneous values. This implies that all of the present algorithms are valid (including those of Piantadosi), but that microchip encoding errors may exist in the instrument used by Piantadosi.

Adult↗
PubMed1996

Midazolam following open heart surgery in children: haemodynamic effects of a loading dose.

Our objective was to establish the safety and effectiveness of a loading dose of midazolam for postoperative sedation of children recovering from open heart surgery; a prospective randomized placebo-controlled double-blind study was done with subjects randomized to three groups according to loading dose. I = 0.08 mg.kg-1; II = 0.04 mg.kg-1; and III = 0.00 mg.kg-1 (placebo). An open label continuous midazolam infusion protocol followed. Haemodynamic parameters were monitored. The study was discontinued following an adverse event involving the 23rd subject. When data for all 23 subjects were combined, there was a mean decrease of 10% in blood pressure (BP) 30 min after the loading dose (P < 0.001). Heart rate change was less significant. Clinicians identified four hypotensive episodes as temporally associated with the midazolam load, two each in Groups I (0.08 mg.kg-1) and III (placebo). One subject in Group I (the 23rd) became hypotensive within five min of receiving the loading dose, had a difficult clinical course and died four weeks postoperatively. We cannot conclude that the loading dose of midazolam had any systematic haemodynamic effect in our study population. Although the clinical course of the 23rd subject suggests a subset of more susceptible children (those who receive opioid analgesia with midazolam, are volume-restricted, and/or undergo more complex forms of surgical correction), many critical care patients are inherently physiologically unstable, and concluding clinically that blood pressure fluctuation is drug related may be erroneous.

Blood Pressure↗
PubMed1996

Demographics of alpine skiing and snowboarding injury: lessons for prevention programs.

OBJECTIVE: To establish the demographics of ski injury in relation to age, gender, and perceived cause during a representative season to identify potential injury prevention strategies. SETTING: Blackcomb Mountain, a world class ski resort in British Columbia, Canada. METHODS: Data were collected from the lift ticket records and from ski patrol injury reports for one season, November to May 1991-2. RESULTS: There were 720,066 skier and snowboarder day visits counted by the mountain's lift ticket records, with a total of 2,092 injury reports (incidence 2.91 per 1,000 day visits). Of those with significant injuries (those requiring physician care), 1,210 (58%) were male. The highest injury rate was among children (age 7-12) and teens (age 13-17) with incidences of 3.18 and 3.34 significant injuries per 1,000 skier days, respectively. Head and face injuries constituted 17% and 22% of injuries, respectively in these groups. Overall 22% of head and face injuries were severe enough to cause loss of consciousness or clinical signs of concussion. This was the body region injured most frequently in males. For females over 7 years of age, the knee was the most common site of injury. For youths, the incidence of injuries during school organized activities was 25% higher than during other outings. CONCLUSIONS: The vulnerability of school group participants suggests special education is warranted. The high incidence of head injuries, particularly among young males, needs to be addressed. In light of the high proportion of this group who already wear helmets, the role of helmets in both protection and possible causation of head injury needs objective research.

Adolescent↗