Browsing by Author "Ocobock, Cara"
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Item Assessment of digit skin temperatures via infrared thermography under different climatic conditions.(2024-03-21) Boettger, Chloe; Tran, Baonhu; Ward, Lyndee; Counts, Caroline; Cowgill, Libby; Ocobock, Cara; Cho, Elizabeth; Maddux, ScottThe responsiveness of the manual/pedal digits (i.e., finger/toes) to temperature changes makes them valuable indicators of thermoregulatory function. Further, while infrared thermography is used in many medical settings, its utility in assessing acute changes in digit skin temperatures remains poorly established. Accordingly, this research investigated the use of forward-looking infrared (FLIR) imaging as a methodological tool for analyzing digital skin temperatures across varying climatic conditions. A Teledyne FLIR E76 camera and associated FLIR Studio software were used to assess peripheral digit skin temperatures in a sample of 25 living human subjects (12 female, 13 male). Images of each hand and foot were captured every 5 minutes over a 45-minute period during exposure to four controlled climatic conditions in an environmental chamber. These experimental conditions included a control (22°C and 50% humidity), hot-humid (37°C and 85% humidity), hot-dry (44°C and 15% humidity), and cold-dry (5°C and 80% humidity) exposures. All images were taken at a perpendicular angle from the skin surface at a distance of 0.45 mm, as measured using the camera’s laser-guided range finder function. Baseline images were similarly taken during a preliminary rest period prior to each experimental exposure. This resulted in a total of 2,200 images collected from the left hand and left foot of the 25 participants. Following theoretical expectations, preliminary findings indicate peripheral digit temperatures predictably decrease during the cold-dry exposure, while the hot-dry and hot-humid exposures induce increases in digit temperatures. These preliminary results suggest that infrared thermography likely provides an expedient mechanism for accurately assessing peripheral skin temperatures in humans under different climatic conditions. Infrared thermography may thus have valuable applications for assessing thermoregulatory function in both clinical and research settings.Item Evaluating philtrum-to-tragus distance as an external predictor of nasal passage dimensions: A computed tomography (CT) approach(2024-03-21) Counts, Caroline; Boettger, Chloe; Tran, Baonhu; Ward, Lyndee; Cowgill, Libby; Ocobock, Cara; Cho, Elizabeth; Maddux, ScottAccurate quantification of nasopharyngeal temperature requires the placement of a flexible intranasal probe into the upper or mid-nasopharynx. Yet, without guidance from medical imaging, data shows that in practice less than half of nasopharyngeal temperature probes are optimally positioned. Still, previous studies have suggested that the distance between the philtrum (external nose) to tragus (external ear) provides a reliable predictor of internal nasal passage dimensions. However, previous attempts to verify the accuracy of this external proxy have returned equivocal results. Accordingly, this study employed measurements collected from CT scans of 11 living participants (4 female, 7 male) to assess associations between external philtrum-tragus length and internal lengths of the nasal cavity, nasopharynx, and total nasal passage (i.e., cavity + pharynx). Results show statistically significant correlations between philtrum-tragus length and internal measurements of nasal cavity (r=0.412, p=0.033) and total nasal passage (r=0.502, p=0.015) length. In contrast, no significant correlation was identified between philtrum-tragus length and nasopharynx length (r=0.110, p=0.320). Despite the small size of the study sample, these suggest that philtrum-tragus length can provide insights for estimating internal dimensions relating to the location of the end of nasal cavity (i.e., choanal aperture) and the posterior wall of nasopharynx. Thus, this external measurement may enhance the accuracy of intranasal probe placement, especially when medical imaging data (i.e., radiographs, CT, MRI) are not available for guidance. Accordingly, additional investigation into the applied utility of philtrum-tragus length with larger sample sizes appears warranted.Item Every breath you take: Experimentally investigating respiratory responses to hot environments(2024-03-21) Tran, Baonhu; Ward, Lyndee; Boettger, Chloe; Counts, Caroline; Cowgill, Libby; Ocobock, Cara; Cho, Elizabeth; Maddux, ScottThe human body loses heat to the environment through two mechanisms: the skin and the respiratory system. Accordingly, it has previously been hypothesized that respiration may play an important role in overall thermoregulatory responses to heat stress. However, previous studies investigating respiratory responses to heat have generally failed to account for variation in humidity levels seen across hot environments (i.e., hot-humid vs. hot-dry conditions). Thus, the goal of this study was to experimentally test for potential differences in respiratory responses to heat stress given variation in air humidity. A mixed-sex sample of human volunteers (5 females, 6 males) were subjected to three different climatic conditions: room temperature (22°C, 50% relative humidity (RH)), hot-dry (44°C, 15% RH), and hot-humid (37°C, 85% RH).Test subjects were exposed to each climatic condition for 45 minutes, with metabolic and respiratory data collected for 30 minutes using a wearable COSMED K-5 metabolic system. Respiratory frequency (Rf, breaths/minute) and oxygen consumption (VO2, ml/minute)were assessed. Results of a repeated-measures ANOVA found a statistically significant difference in Rf values between the climatic conditions (F=5.05, p=0.017). Subsequent Tukey-Kramer multiple-comparison post-hoc test results indicate that participants exhibited significantly higher Rf values in the hot-dry condition (mean=17.498) compared to the room temperature (mean=15.859)and hot-humid (mean=15.764) conditions. In contrast, no significant differences for VO2 consumption between the three climatic conditions (F=2.33, p=0.123) were found. These results indicate that in the hot-dry climatic condition, participants breathe more frequently without increasing the total amount of air inspired (i.e., taking more frequent but shallower breaths). These results are largely consistent with findings of previous studies that have demonstrated similar physiological responses to heat stress. Furthermore, our study highlights the existence of differential respiratory responses in hot-dry vs. hot-humid conditions, suggesting that humidity may play an important role in mediating respiratory responses to heat stress. Additional research into the impacts of humidity on respiratory function is thus warranted.