Faith A. Gagnon

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.

Diurnal changes in the profile shape and range of motion of the back

The diurnal height change reported to occur in young adults was investigated to characterize changes in the lumbar range of motion, spinal profile, and range of motion of the back. Twelve subjects aged 18–22 years were measured using stereophotography and standard clinical examinations in the evening and after a minimum of 8 hours of complete bed rest. The average increase in height was 20 mm. Forty percent of the height increase took place in the lumbar spine without change in the depth of the lordosis, and forty percent took place in the thoracic curve with a decrease in the kyphosis. The remaining 20% of the height increase was not located, but no measurements were taken of the cervical spine. Range of motion studies revealed that lumbar flexion, as measured using the lumber flexion increment was decreased in the morning, and straight leg rales was decreased when measured clinically but not when measured photographically. Extension, rotation, and femoral stretch test were not affected. The authors conclude that stereophotogrammetry offers an accurate, noninvasive way to study spinal profiles. Further work is needed to assess and quantify the relative motion of the skin and the underlying structures.

Diurnal changes in lumbar intervertebral distance, measured using ultrasound.

Study Design This study measured the distances between the tips of the transverse processes of adjacent lumbar vertebrae (L1‐L4) in the same subjects after 1 day of normal activities and again the next morning. Objectives To determine the feasibility of directly measuring the lumbar intervertebral distance using ultrasound and to determine the magnitude of the diurnal change in the intervertebral distance. Summary of Background Data A diurnal variation in height results from, in part, a decrease in height of the intervertebral discs with loading of the spine during the day. Previous estimates of the diurnal changes in disc height have used radiologic, stereophotographic, and magnetic resonance imaging techniques. No previous study has used ultrasound imaging. Methods Ultrasound was used to measure the distance between the tips of adjacent lumbar vertebral transverse processes. Measurements were made on six occasions in each of seven subjects after 6:00 PM in the evening and again the following morning before rising. Results The distance between the tips of adjacent transverse processes could be measured, within an individual, with a reproducibility of better than ± 7.5% coefficient of variation. Reproducibility of the measurement of the total distance between L1 and L4 was better than ± 4%. The intervertebral distances between L1 and L4 were significantly greater in the morning than in the evening. The average diurnal change in the total intervertebral distance L1‐L4 was 5.3 mm. Conclusions The study confirms the feasibility of using ultrasound to directly measure changes in the distances between the lumbar vertebrae.

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 ...

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 averager2, 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.

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.RésuméObjectif: Des complications neurologiques peuvent survenir à la suite de circulation extracorporelle (CEC) pendant une intervention chirurgicale. Nous avons réalisé une étude randomisée, contrôlée et à l’insu, afin de déterminer l’effet du propofol sur l’état redox du cytochrome aa3 et d’évaluer sa capacité à réduire les complications neurologiques.Méthode: L’étude a porté sur 24 enfants (âge moyen: 3,3 ans; poids moyen: 14,4 kg) qui devaient subir une intervention avec CEC. Ils ont reçu, dans le groupe expérimental P, suffisamment de propofol pour éliminer l’activité électrique cérébrale comme l’indiquait l’EEG (c.-à-d. la suppression des bouffées du tracé EEG). Le second groupe, témoin (T), n’a pas reçu de propofol. Les données spectrographiques près de l’infrarouge ont été recueillies à une seconde d’intervalle tout au long de l’opération. Un examen neurologique préopératoire et postopératoire a été fait par un médecin impartial. La modification des données sur le cytochrome aa3 enregistrées à 10 min d’intervalle (10, 20, 30, 40 min) après le début de la CEC, a été comparée entre les groupes par des analyses de variance pour mesures répétées.Résultats: Les modèles de changement d’état redox du cytochrome ont été différents d’un groupe à l’autre (P<0,002). Le modèle de changement dans le groupe P a été similaire à celui qu’on a observé chez les patients hypothermiques du groupe T. On pouvait établir des corrélations entre le changement d’état du cytochrome aa3 et la température chez les sujets témoins. Aucune complication neurologique importante n’est survenue dans un groupe ou l’autre.Conclusion: Le propofol semble maintenir l’équilibre entre l’offre et la demande d’énergie cérébrale pendant une intervention chirurgicale avec circulation extracorporelle. Il pourrait ainsi réduire, en théorie, l’incidence ou la sévérité des complications neurologiques.

Critical Incident Stress Intervention After Loss of an Air Ambulance: Two-year Follow Up

OBJECTIVE Following an air ambulance crash with five fatalities, critical incident stress debriefing (CISD) was provided for involved paramedics, physicians, and nurses. A study was conducted to evaluate the long-term effects of a critical incident with critical incident stress debriefing according to the Mitchell model. METHODS Six months following the incident, empirically designed questionnaires were mailed to all transport paramedics and directly involved medical staff, and a random sample of both nurses from the dispatch/receiving institution and paramedics from around the province. Twenty-four months post-incident, all members of the transport paramedics completed the Impact of Events Scale and the General Health Questionnaires. RESULTS There were no differences between groups on any scores, except for disturbed sleep patterns, bad dreams, and the need for personal counseling being greater among transport paramedics at one day. There was no correlation between how well the deceased individuals were known, amount of debriefing, and symptom severity. A trend was seen for those with pre-existing stress management routines to have less severe symptoms at six months (p = 0.07). At two years, 16% of transport paramedics still had significant abnormal behavior. CONCLUSIONS CISD did not appear to affect the severity of stress symptoms, whereas having pre-existing stress management strategies may. These findings give justification for proceeding to a randomized, controlled trial of different levels of critical incident stress intervention.

Health Promoting Schools Provide Community-Based Learning Opportunities Conducive to Careers in Rural Practice

The World Health Organization conceived “health-promoting schools” as a means of providing the information and support systems necessary for the worldwide changes in behavior that are needed to improve health globally and decrease health care costs. We developed and evaluated a model of progressively implementing health-promoting schools with support from university medical school trainees in Canada and Uganda. The model uses oral health as a medium for establishing rapport and success around a topic with little stigma. The evaluation involved questionnaires of the Canadian trainees about practice intentions before and after involvement in the health-promoting schools to determine whether community-based learning in health-promoting schools resulted in more trainees planning to work in rural areas or underserved countries. We found that Canadian medical trainees cited their personal involvement and perceived ability to effect significant and identifiable positive change in both the school children and the community as reasons why they were more willing to practice in rural or under-served areas.

The cost-benefit of pulse-oximeter use in the prehospital environment.

INTRODUCTION Pulse-oximetry has proven clinical value in Emergency Departments and Intensive Care Units. In the prehospital environment, oxygen is given routinely in many situations. It was hypothesized that the use of pulse oximeters in the prehospital setting would provide a measurable cost-benefit by reducing the amount of oxygen used. METHODS This was a prospective study conducted at 12 ambulance stations (average transport times > 20 minutes). Standard care protocols and paramedic assessments were used to determine which patients received oxygen and the initial flow rate used. Pulse-oximetry measurements (SpO2) were then taken. If SpO2 fell below 92% or rose above 96% (except in patients with chest pain), oxygen (O2) flow rates were adjusted. Costs of oxygen use were calculated: volume that would have been used based on initial flow rate; and volume actually used based on actual flow rates and transport time. RESULTS A total of 1,907 patients were recruited. Oximetry and complete data were obtained on 1,787 (94%). Of these, 1,329 (74%) received O2 by standard protocol: 389 (27.5%) had the O2 flow decreased; 52 had it discontinued. Eighty-seven patients (6%) not requiring O2 standard protocol were hypoxemic (SpO2 < 92%) by oximetry, and 71 patients (5%) receiving oxygen required flow rate increases. Overall, O2 consumption was reduced by 26% resulting in a cost-savings of

NIRS monitoring of brain and spinal cord — detection of adverse intraoperative events

0.20/patient. Prehospital pulse-oximetry allows unnecessary or excessive oxygen therapy to be avoided in up to 55% of patients transported by ambulance and can help to identify suboptimally oxygenated patients (11%). CONCLUSIONS Rationalizing the O2 administration using pulse-oximetry reduced O2 consumption. Other health care savings likely would result from a reduced incidence of suboptimal oxygenation. Oxygen cost-saving justifies oximeter purchase for each ambulance annually where patient volume exceeds 1,750, less frequently for lower call volumes, or in those services where the mean transport time is less than the 23 minute average noted in this study.