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Biomedical subjects

A J Macnab

Publications and source records attributed to A J Macnab.

At least 37 records · Page 2Linked to original sources
PubMed1996

Oximeter reliability in a subzero environment.

BACKGROUND: Pulse oximeters optimize care in the pre-hospital setting. As British Columbia ambulance teams often provide care in subzero temperatures, we conducted a study to determine the reliability of 3 commercially-available portable oximeters in a subzero environment. NULL HYPOTHESIS: We hypothesized that there is no significant difference between SaO2 readings obtained using a pulse oximeter at room temperature and a pulse oximeter operating at sub-zero temperatures. METHODS: Subjects were stable normothermic children in intensive care on Hewlett Packard monitors (control unit) at room temperature. The test units were packed in dry ice in an insulated bin (temperature - 15 degrees C to -30 degrees C) and their sensors placed on the subjects, contralateral to the control sensors. Data were collected simultaneously from test and control units immediately following validation of control unit values by co-oximetry (blood gas). RESULTS: No data were unacceptable. Two units (Propaq 106EC and Nonin 8500N) functioned well to < -15 degrees C, providing data comparable to those obtained from the control unit (p < 0.001). The Siemens Micro O2 did not function at the temperatures tested. CONCLUSIONS: Monitor users who require equipment to function in subzero environments (military, Coast Guard, Mountain Rescue) should ensure that function is reliable, and could test units using this method.

Analysis of Variance↗
PubMed1995

Effective interventions for nearly drowned children.

Near-drowning, one of the great tragedies in emergency pediatrics, is largely preventable. It generates particular concern and frustration among those who must treat its victims and their families. Should every drowned child be resuscitated? What treatment will minimize the risk of secondary brain injury?

Adolescent↗
PubMed1994

The Vancouver sedative recovery scale for children: validation and reliability of scoring based on videotaped instruction.

We originally developed and tested the Vancouver Sedative Recovery Scale (VSRS) to measure recovery from sedation following paediatric open heart surgery and reported excellent clinical inter-observer reliability. We now report a new study using videotape instruction of novice raters and videotaped case examples to determine whether the instruction produces adequate skill with the VSRS. Inter-rater reliability was assessed using videotapes of 16 children across a range of ages (six months to six years), and all levels of sedation (unresponsive to fully awake). Variably randomized subsets of six of the 16 test cases were randomly assigned to be rated by each of 16 video-instructed ICU staff volunteers, according to a balanced incomplete block design, such that every pair of raters assessed two children in common. The validity of the ratings from the video-instructed raters was assessed by comparison with "gold standard" scores from two experts who rated all 16 children clinically as the test cases were videotaped. The experts were in agreement themselves (intraclass correlation of 0.976). The correlation between the novice scores (average of six ratings per video) and the live clinical scores (average of two expert ratings) was 0.977 over the 16 test cases. On average, the mean expert rating was slightly higher, but the difference was negligible. (The differences between the mean ratings of the experts and novices for 13 of the 16 videos are very close to zero, while the other three differences, from technically less good videos, are two standard deviations away from zero). The VSRS, video instruction method and incomplete block design may be of use to other clinicians and investigators.

Anesthesia Recovery Period↗
PubMed1993

Carbamazepine poisoning in children.

Carbamazepine poisoning in children remains a significant problem for the emergency physician. We report 16 cases of toxicity at British Columbia Children's Hospital and discuss presenting symptoms, treatment, and hospital course. Pharmacology, drug interactions, resulting in carbamazepine toxicity, and treatment guidelines are summarized.

Adolescent↗
PubMed1992

Paediatric inter-facility transport: the parents' perspective.

A telephone survey was conducted to evaluate the impact on families of inter-facility paediatric transport to a tertiary care centre. The 54 families who responded were almost unanimous in their appreciation of the transport service and the expertise of the attendants. However, many experienced problems, including finances, child care, travel arrangements and accommodation. Most problems were encountered by those who did not accompany the child in the transport vehicle, lived at a distance so that they could not commute and did not use hospital accommodation. Further research is suggested to assess the extent of the problems families face and to determine appropriate solutions.

Adolescent↗
PubMed1991

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 Cronbach's alpha was excellent: 0.85. Interobserver agreement or reliability as measured by intraclass correlation was also very high: 0.90; and for individual items Cohen's 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.

Anesthesia Recovery Period↗
PubMed1991

Hypospadias after assisted reproduction incorporating in vitro fertilization and gamete intrafallopian transfer.

OBJECTIVE: To determine incidence of hypospadias in infants born as a result of assisted reproductive technology (ART). DESIGN: Prospective data collection. SETTING: Parents with various forms of infertility attended an in-hospital in vitro fertilization program. PATIENTS: Two of the 53 male infants, conceived as a result of ART over a 3-year period, were born with hypospadias. INTERVENTIONS: Patient no. 1 underwent follicular stimulation (17 ampules of human menopausal gonadotropin (hMG), followed by 10,000 IU of human chorionic gonadotropin (hCG) 60 hours after the last hMG). Patient no. 2 underwent follicular stimulation with clomiphene citrate 100 mg/d from days 3 to 7, followed by 14 ampules of hMG starting day 6, and 10,000 IU of hCG 30 hours after her last hMG. MAIN OUTCOME MEASURES: All infants were examined in the immediate postpartum period for congenital anomalies. RESULTS: Infant no. 1, one of a set of dizygotic twins, had penoscrotal hypospadias, with normal renal sonogram and chromosomal studies. Infant no. 2 had glandular hypospadias with the urinary meatus displaced to the border of the glans. CONCLUSION: This high incidence raises concern about possible links between assisted reproduction and hypospadias.

Adult↗
PubMed1991

Cardiac anomalies complicating congenital contractural arachnodactyly.

A newborn boy with congenital contractural arachnodactyly (CCA) was found to have an atrial septal defect, ventricular septal defect, patent ductus arteriosus, and aortic arch anomalies. These resulted in congestive failure but subsequent progressive dilatation of both great arteries and development of aortic regurgitation were associated with eventual cardiorespiratory failure and death at 11.5 months. Others have noted that cardiac anomalies in CCA may be comparable with those of infantile Marfan's syndrome. Our case further extends the spectrum of cardiac abnormalities in CCA and substantiates that there is overlap with infantile Marfan's syndrome. This fact and our literature review suggest that early and complete cardiac assessment is necessary for appropriate management and evaluation of prognosis in any newborn infant with findings suggestive of either condition.

Abnormalities, Multiple↗
PubMed1991

Optimal escort for interhospital transport of pediatric emergencies.

The charts of 130 seriously ill or injured children transported to tertiary level intensive care were examined to determine the incidence of secondary insults incurred, as a function of escort training. Of all insults incurred, approximately 8% occurred with specialized pediatric transport escorts who were accompanied by a tertiary care physician (Group III, n = 52); 20% with specialized pediatric transport escorts alone (Group II, n = 44); and 72% with escorts who had not received specialized pediatric transport training (Group I, n = 34). Based on our results, we recommend that all transport coordinators review the qualifications and experience of their transport team members and all potential escorts to assess their ability to provide optimal care for the children they transport, particularly during long journeys, transfer by air, and when serious illness or injury is involved.

Brain Injuries↗
PubMed1990

Oximetry in children recovering from deep hypothermia for cardiac surgery.

Although pulse oximetry is a potentially useful diagnostic tool in the treatment of children after major open heart surgery, there are concerns regarding its reliability for measuring oxygen saturation (SaO2) in hypothermic or low perfusion states. To test pulse oximeter reliability in children under these conditions, our study compared 187 SaO2 pulse oximeter readings (Biox 3700) with simultaneous hemoximeter (OSM2, Radiometer) readings from 56 children rewarming after open heart surgery. Ages ranged from 4 months to 18 yr; temperatures ranged from 23.5 degrees to 38 degrees C (toe) and 31.3 degrees to 40.8 degrees C (core). The mean pulse oximeter SaO2 reading was 94.90% (SD 7.18, range 54% to 100%), mean hemoximeter reading was 96.07% (SD 7.06; minimum 54%; maximum 100%). The correlation between the readings was high (r = .88, p less than .005), and was not affected by low core temperature. When oximeter and cardiac monitor pulse rates coincided, the oximeter SaO2 value was within +/- 5% (p less than .05). We conclude that the Biox 3700 oximeter is reliable for noninvasive SaO2 monitoring in mild to moderately hypothermic children after open heart surgery, particularly when oximeter and cardiac heart rates coincide. Further studies are needed to confirm our findings in children with core temperatures less than 31.3 degrees C, and when other oximeters are used.

Adolescent↗
PubMed1990

In-flight stabilization of oxygen saturation by control of altitude for severe respiratory insufficiency.

A 4,907-mile medical air transport recently took place between Vancouver, Canada, and London, England. The patient was a 6-year-old boy with multiple pleural, pulmonary, and pericardial hemangiomata who required heart-lung transplant. Because his respiratory function was so poor (including oxygen-induced hypercarbia and sleep-induced hypoxia), a Lear 35 was used. The aircraft made a low altitude flight possible, allowing adjustment of cabin pressure to overcome the child's sensitivity to any significant reduction in partial pressure and to minimize his need for supplemental oxygen. Clinical observation and monitoring using oximetry and transcutaneous blood gas measurements were carried out en route to warn of excessive altitude effects. Sequential increases in altitude were made once oxygenation had stabilized at each cabin pressure. Cabin pressure was not allowed to rise above 3,700 ft to ensure an oxygen saturation level of at least 80%. The transport was accomplished successfully with no requirement for intervention. This approach to in-flight management has applications for other aero-medical transports.

Acute Disease↗
PubMed1988

Visual loss following traumatic asphyxia in children.

Two young children suffered loss of vision in separate incidents following traumatic asphyxia. Visual loss secondary to trauma can occur from a variety of causes. This is apparently the first description of traumatic asphyxia causing visual loss in children. In children, visual impairment is easily missed unless the degree of handicap is severe. All children should have their fundi and visual acuity assessed before discharge following significant trauma, including all episodes of traumatic asphyxia.

Asphyxia↗