Transcutaneous and End-Tidal CO2 Measurements in Hypoxia and Hyperoxia

BACKGROUND: Transcutaneous measurement of carbon dioxide (CO2) has been proposed for physiological monitoring of tactical jet aircrew because in some clinical settings it mirrors arterial CO2 partial pressure (Paco2). End-tidal monitoring in laboratory settings is known to give high-fidelity estimates of Paco2.METHODS: The correspondence between end-tidal (PETco2) and transcutaneous Pco2 (tcPco2) was examined in healthy volunteers under laboratory conditions of hyperoxia and hypoxia. Rest and exercise, skin heating and cooling, hyperventilation, and induced CO2 retention were employed.RESULTS: Neither measure followed all known changes in Paco2 and tcPco2 changed when the skin temperature near the probe changed. Bland-Altman analysis showed significant nonzero slopes under most conditions. Regression analysis indicated that oxygen partial pressure (Po2) in tissue measured as transcutaneous Po2 (tcPo2) is an important explanatory variable for tcPco2 in addition to PETco2, and that local skin temperature also has an effect. Additionally, absorption atelectasis from breathing 100% O2 may cause PETco2 to deviate from Paco2.DISCUSSION: Even as a trend indicator for Paco2, tcPco2 is not useful under conditions that resemble those in the highly dynamic tactical jet aircraft environment. PETco2 is also not a good indicator of CO2 status in pilots who breathe nearly 100% O2.Shykoff BE, Lee LR, Gallo M, Griswold CA. Transcutaneous and end-tidal CO2 measurements in hypoxia and hyperoxia. Aerosp Med Hum Perform. 2021; 92(11):864-872.

Cardiorespiratory and Thermoregulatory Parameters Are Good Surrogates for Measuring Physical Fatigue during a Simulated Construction Task

Cardiorespiratory (e.g., heart rate and breathing rate) and thermoregulatory (e.g., local skin temperature and electrodermal activity) responses are controlled by the sympathetic nervous system. To cope with increased physical workload, the sympathetic system upregulates its activity to generate greater sympathetic responses (i.e., increased heart rate and respiratory rate). Therefore, physiological measures may have the potential to evaluate changes in physical condition (including fatigue) during functional tasks. This study aimed to quantify physical fatigue using wearable cardiorespiratory and thermoregulatory sensors during a simulated construction task. Twenty-five healthy individuals (mean age, 31.8 ± 1.8 years) were recruited. Participants were instructed to perform 30 min of a simulated manual material handling task in a laboratory. The experimental setup comprised a station A, a 10-metre walking platform, and a station B. Each participant was asked to pick up a 15 kg ergonomically-designed wooden box from station A and then carried it along the platform and dropped it at station B. The task was repeated from B to A and then A to B until the participants perceived a fatigue level > 15 out of 20 on the Borg-20 scale. Heart rate, breathing rate, local skin temperature, and electrodermal activity at the wrist were measured by wearable sensors and the perceived physical fatigue was assessed using the Borg-20 scale at baseline, 15 min, and 30 min from the baseline. There were significant increases in the heart rate (mean changes: 50 ± 13.3 beats/min), breathing rate (mean changes: 9.8 ± 4.1 breaths), local skin temperature (mean changes: 3.4 ± 1.9 °C), electrodermal activity at the right wrist (mean changes: 7.1 ± 3.8 µS/cm), and subjective physical fatigue (mean changes: 8.8 ± 0.6 levels) at the end of the simulated construction task (p < 0.05). Heart rate and breathing rate at 15 and 30 min were significantly correlated with the corresponding subjective Borg scores (p < 0.01). Local skin temperature at 30 min was significantly correlated with the corresponding Borg scores (p < 0.05). However, electrodermal activity at the right wrist was not associated with Borg scores at any time points. The results implied cardiorespiratory parameters and local skin temperature were good surrogates for measuring physical fatigue. Conversely, electrodermal activity at the right wrist was unrelated to physical fatigue. Future field studies should investigate the sensitivity of various cardiorespiratory and thermoregulatory parameters for real time physical fatigue monitoring in construction sites.

Effect of Heat-Producing Needling Technique on the Local Skin Temperature: Clinical Dataset

The heat-producing needling technique is a special compound manipulating procedure on the acupuncture needle which has been recorded to produce a warm sensation in the body in ancient TCM literature. This randomized, subject-blinded clinical study was performed to examine the effect of heat-producing acupuncture treatment on the ST36 local skin temperature. A total of 30 healthy participants received four successive sessions of heat-producing acupuncture treatment, non-acupoint heat-producing acupuncture treatment, normal stable acupuncture treatment, and non-invasive sham acupuncture treatment at the ST36 acupoint in a random sequence. Within each session, the local ST36 skin temperature and basal body temperature of each participant were measured at 1 min before needle insertion, just after needle insertion and manipulation (if any), 5 min after needle insertion with needle removal immediately after temperature taking, and 5 min after needle removal. Furthermore, the participants were also required to declare their needling and heat sensation felt during the acupuncture needling treatment period using a visual analogue scale from 1 to 10 immediately after each treatment session. This data descriptor presents all the clinical data obtained in the above mentioned study.

Human wetness perception of fabrics under dynamic skin contact

This experiment studied textile (surface texture, thickness) and non-textile (local skin temperature changes, stickiness sensation and fabric-to-skin pressure) parameters affecting skin wetness perception under dynamic interactions. Changes in fabric texture sensation between WET and DRY states and their effect on pleasantness were also studied. The surface texture of eight fabric samples, selected for their different structures, was determined from surface roughness measurements using the Kawabata Evaluation System. Sixteen participants assessed fabric wetness perception, at high pressure and low pressure conditions, stickiness, texture and pleasantness sensation on the ventral forearm. Differences in wetness perception (p < 0.05) were not determined by texture properties and/or texture sensation. Stickiness sensation and local skin temperature drop were determined as predictors of wetness perception (r2 = 0.89), and although thickness did not correlate with wetness perception directly, when combined with stickiness sensation it provided a similar predictive power (r2 = 0.86). Greater (p < 0.05) wetness perception responses at high pressure were observed compared with low pressure. Texture sensation affected pleasantness in DRY (r2 = 0.89) and WET (r2 = 0.93). In WET, pleasantness was significantly reduced (p < 0.05) compared to DRY, likely due to the concomitant increase in texture sensation (p < 0.05). In summary, under dynamic conditions, changes in stickiness sensation and wetness perception could not be attributed to fabric texture properties (i.e. surface roughness) measured by the Kawabata Evaluation System. In dynamic conditions thickness or skin temperature drop can predict fabric wetness perception only when including stickiness sensation data.