Biomedical subjects

Justin Walls

Publications and source records attributed to Justin Walls.

4 recordsLinked to original sources

PubMed2006

Stability of the EasyOne ultrasonic spirometer for use in general practice.

OBJECTIVE AND BACKGROUND: Spirometry is recommended for the diagnosis and management of chronic respiratory diseases in the community. Spirometer accuracy is critical, but few general practitioners meet the American Thoracic Society and European Respiratory Society (ATS/ERS) recommendation for daily calibration. The aim of this study was to assess the accuracy and stability of a portable ultrasonic spirometer (EasyOne) that the manufacturer claims does not require regular calibration. METHODS: Six EasyOne spirometers were used in a practice-based spirometry study. Inspiratory and expiratory accuracy was checked periodically using a certified 3-L syringe. Paired calibration checks were performed using a dedicated mouthpiece assembly (spirette) and randomly selected spirettes. RESULTS: The six spirometers were used for up to 26 weeks (mean 23.9 weeks) and a total of 1041 spirometry tests and 75 syringe calibrations were performed. All inspiratory and expiratory calibration checks using a dedicated or randomly selected spirette met the ATS/ERS accuracy criterion (3.00+/-0.105 L). The mean (range) expiratory volume deviation from target volume (3.00 L) was 0.011 L (-0.06-0.09 L) using a dedicated spirette and 0.046 L (-0.09-0.10 L) using randomly selected spirettes. The deviation from target was not affected by the mean flow generated during the calibration procedure. There was no change in calibration during the study. CONCLUSIONS: This study supports the manufacturer's claim that the EasyOne spirometer maintains its calibration during routine clinical use in general practice and does not require daily calibration as specified in international spirometry guidelines.

Equipment Design↗

PubMed2006

Airway distensibility in normal and asthmatic subjects and partitioning of the Fowler dead space.

Anatomical dead space measured by the Fowler method (VDF) is the sum of 2 serial volume compartments (VDF = VDp1 + VDp2). VDF has been shown to increase linearly with end-inspiratory lung volume (EILV) and the gradient of the relationship (DeltaVDF) has been used as an index of airway distensibility. The aim of this study was to partition VDF into its serial compartments VDp1 and VDp2 to test the hypothesis that, given the greater distensibility of distal airways, VDp2 would demonstrate greater volume dependence than VDp1. The relationships between each measure of VD (VDF, VDp1, and VDp2) and EILV were studied in 16 healthy subjects and 16 mildly asthmatic subjects. Significant (p < 0.05) linear relationships were obtained between each measure of VD and EILV in both subject groups. Changes in VDp1 with EILV (DeltaVDp1) accounted for 78.6% +/- 5.6% (mean +/- SEM) and 72.6% +/- 6.3% of DeltaVDF in the healthy and asthmatic groups, respectively. DeltaVDp1 was greater in the healthy subjects than in asthmatic subjects (18.4 versus 13.1 mL/L, p = 0.005). We conclude that in both asthmatic and healthy subjects, the major component of DeltaVDF was DeltaVDp1 and not DeltaVDp2, as originally hypothesized. We believe our results are reflecting the degree of asynchronous airway emptying.

Adult↗

PubMed2003

Reflective critique and collaborative practice in evaluation: promoting change in medical education.

The School of Medicine at the University of Tasmania has recently begun to implement a process of curriculum evaluation,which aims to reflect contemporary best practice in evaluation in tertiary pedagogy and medical education. Best practice must accommodate a broadening interest in cooperative and collaborative evaluation strategies among stakeholders, advances in applied qualitative educational research and recognition that critical reflection on practice is the cornerstone of professional education. This paper reports a recent evaluation strategy in a specific year-long unit in the second year of a six-year undergraduate medical degree. The paper begins by presenting the context; it then discusses and rationalises the evaluation strategy and presents findings. The paper concludes by arguing that curriculum evaluation as best practice must be reflective, informed by the scholarship of medical education, and internalized as a dynamic process that can promote sustainable change and improvement in medical curricula. Such an approach will contribute to an undergraduate medical curriculum that prepares students for the demands and complexities of medical practice.

Cooperative Behavior↗

PubMed2002

Exercise-induced oxyhaemoglobin desaturation, ventilatory limitation and lung diffusing capacity in women during and after exercise.

Arterial haemoglobin saturation during exercise in healthy young women [eight subjects mean (SEM) age 20.8 (1.8) years] was measured to confirm the theory that young women experience exercise-induced arterial hypoxaemia (EIAH) at a lower relative percentage of maximal oxygen uptake (VO(2max)) than has been documented in their male counterparts. To determine if flow limitation [the percentage of the tidal volume ( V(T)) that met or exceeded the boundary established by multiple maximal expiratory manoeuvres] and/or post-exercise lung diffusing capacity are linked to EIAH in women, and to investigate the influence of exercise intensity and duration on post-exercise carbon monoxide lung diffusing capacity ( D(L, CO)), these parameters were measured during and after three exercise tests (incremental test until exhaustion, 5 km run and 5 km run with sprint). All subjects experienced physiologically significant EIAH (a fall of more than 3% in oxygen saturation of arterial blood from levels at rest) and seven subjects experienced flow limitation during the VO(2max) protocol [mean (SD) 12.2 (8.8)% of V(T)]. Even though there was no significant relationship between aerobic capacity and the degree of flow limitation ( r=0.33, P>0.05), the flow limitation was related to absolute ventilation in the subjects studied ( r=0.82, P<0.05). There was no significant relationship between decrements in post exercise D(L, CO) and EIAH ( r=0.05, P>0.05), however there was a strong correlation between the extent of flow limitation (% of V(T)) and EIAH ( r=0.71). Significant decreases in D(L, CO) lasted for up to 16 h after each of the exercise tests ( P<0.05) and lasted for a further 8 h after the maximal test ( P<0.05). Exercise intensity was the main contributing factor to the observed decreases in post-exercise D(L, CO) with the percentage of VO(2max) attained during the various tests being significantly related to the fall in D(L, CO) for 1, 2, 3, 16 and 24 h after exercise ( P<0.05). As the appearance of flow limitation closely coincided with the appearance of EIAH, the results from the present study suggest that flow limitation is a contributing factor to EIAH in women although the exact mechanism remains unclear.

Adult↗