The Use of Pulse Oximetry in the Assessment of Acclimatization to High Altitude

Background: Finger pulse oximeters are widely used to monitor physiological responses to high-altitude exposure, the progress of acclimatization, and/or the potential development of high-altitude related diseases. Although there is increasing evidence for its invaluable support at high altitude, some controversy remains, largely due to differences in individual preconditions, evaluation purposes, measurement methods, the use of different devices, and the lacking ability to interpret data correctly. Therefore, this review is aimed at providing information on the functioning of pulse oximeters, appropriate measurement methods and published time courses of pulse oximetry data (peripheral oxygen saturation, (SpO2) and heart rate (HR), recorded at rest and submaximal exercise during exposure to various altitudes. Results: The presented findings from the literature review confirm rather large variations of pulse oximetry measures (SpO2 and HR) during acute exposure and acclimatization to high altitude, related to the varying conditions between studies mentioned above. It turned out that particularly SpO2 levels decrease with acute altitude/hypoxia exposure and partly recover during acclimatization, with an opposite trend of HR. Moreover, the development of acute mountain sickness (AMS) was consistently associated with lower SpO2 values compared to individuals free from AMS. Conclusions: The use of finger pulse oximetry at high altitude is considered as a valuable tool in the evaluation of individual acclimatization to high altitude but also to monitor AMS progression and treatment efficacy

Neškodljivost i djelotvornost glogova ekstrakta WS 1442 i nordijskog hodanja na profil lipida i funkciju endotela: randomizirano, djelomice slijepo probno istraživanje u dobrovoljaca prekomjerne tjelesne težine

Overweight and physical inactivity adversely affect endothelial function and are risk factors for atherosclerosis and cardiovascular disease. Both Crataegus extract WS 1442 and physical exercise exert beneficial effects on endothelial function. We investigated whether WS 1442 and Nordic walking (NW) had comparable effects on endothelial function and lipid profile in overweight subjects. In this partially blinded pilot study, overweight, otherwise healthy volunteers aged 45-75 years were randomized into four groups as follows: WS 1442 2x450 mg/day (WS-standard), WS 1442 2x900 mg/day (WS-double), exercise 2x30 minutes/week (NW-low), and exercise 4x45 minutes/week (NW-high) for 12 weeks. Safety was assessed based on adverse events. Endothelial function testing (EndoPAT®), assessment of endothelial progenitor cells, lipid profiles, and treadmill testing were performed. Sixty subjects participated in the study. At baseline, subjects in WS-standard/-double groups had higher lipid levels and greater impairment of endothelial function. Subjects with impaired endothelial function showed improvement regardless of the type of intervention. Subjects in WS-standard and WS-double groups showed a trend towards modest decrease in triglycerides and modest increase in HDL-cholesterol; most changes were within the normal limits. In NW-low/-high groups, values also remained within the normal range. Exercise capacity improved in both NW groups. WS-double showed no additional benefits over WS-standard. All adverse events were unrelated or improbably related to treatment. In conclusion, WS 1442 and exercise training were safe and showed beneficial effects on endothelial function and lipid profile in overweight but otherwise healthy volunteers; exercise capacity improved only by Nordic walking.Prekomjerna težina i tjelesna neaktivnost štetno djeluju na funkciju endotela i predstavljaju rizične čimbenike za aterosklerozu i srčanožilne bolesti. Glogov ekstrakt WS 1442 i tjelesna aktivnost oboje utječu povoljno na endotelnu funkciju. Ispitivali smo imaju li WS 1442 i nordijsko hodanje (NH) usporedive učinke na endotelnu funkciju i profil lipida u osoba prekomjerne tjelesne težine. U ovom djelomice slijepom probnom istraživanju su inače zdravi dobrovoljci prekomjerne tjelesne težine u dobi od 45 do 75 godina nasumce podijeljeni u četiri skupine: WS 1442 2x450 mg/dan (standardna doza WS), WS 1442 2x900 mg/dan (dvostruka doza WS), tjelovježba 2x30 minuta na tjedan (niska razina NH) i tjelovježba 4x45 minuta na tjedan (visoka razina NH) kroz 12 tjedana. Neškodljivost se procjenjivala na osnovi štetnih događaja. Provedeno je testiranje endotelne funkcije (EndoPAT®), procjena endotelnih progenitorskih stanica, profila lipida te test opterećenja. U istraživanju je sudjelovalo 60 ispitanika. Ispitanici na standardnoj/dvostrukoj dozi WS imali su bazalno više razine lipida i veći poremećaj endotelne funkcije. Ispitanici s poremećenom endotelnom funkcijom pokazali su poboljšanje bez obzira na vrstu intervencije. Ispitanici na standardnoj i dvostrukoj dozi WS pokazivali su tendenciju ka skromnom sniženju triglicerida i skromnom porastu HDL-kolesterola; većina ovih promjena bila je unutar normalnih granica. Uz nisku/visoku razinu NH vrijednosti su također ostale unutar normalnog raspona. Sposobnost za tjelovježbu poboljšala se u objema skupinama NH. Dvostruka razina WS nije pokazala dodatnih koristi u usporedbi sa standardnom dozom WS. Svi štetni događaji bili su nevezani ili malo vjerojatno povezani s tretmanom. U zaključku, WS 1442 i tjelovježba pokazali su se neškodljivima i imali su povoljan učinak na funkciju endotela i profil lipida kod inače zdravih osoba prekomjerne tjelesne težine; sposobnost za tjelovježbu poboljšala se samo pomoću NH

Myocardial Infarction by a Myocardial Bridge in the LAD Combined With Atrioventricular Re-Entrant Supraventricular Tachycardia

We present the case of a patient who presented with palpitations and was found to have atrioventricular re-entrant tachycardia with unusually elevated cardiac biomarkers. A coronary computed tomographic angiography showed a myocardial left anterior descending artery bridge; an accessory pathway was ablated, and cardiac magnetic resonance revealed anteroseptal myocardial infarction resulting from hypoperfusion during tachycardia caused by the left anterior descending artery myocardial bridge. (Level of Difficulty: Intermediate.)

Hypertensive Response to Exercise in Athletes: Unremarkable Finding or Relevant Marker for Future Cardiovascular Complications?

BACKGROUND In the general population, hypertensive response to exercise (HRE) predicts new-onset resting hypertension or other cardiovascular diseases. METHODS PubMed was searched for English articles published between January 1st 2000 and April 30th 2020. Additional studies were identified via reference lists of included studies. 92 papers were selected for full text analysis, finally 30 studies were included. RESULTS The results from 5 follow-up studies suggested an association between HRE and the risk of developing hypertension, while 10 studies reported a link with adverse cardiovascular events in the general population. Another study showed an association between HRE and future hypertension in athletes after a follow-up of 7 years. HRE in athletes was associated with left ventricular hypertrophy in three studies. Two other studies showed a link between HRE and focal myocardial fibrosis in triathletes and myocardial injury, respectively. One study found lower Apoliprotein-1 serum levels in athletes with HRE leading to a higher risk for cardiovascular disease. Only in one study no association with cardiovascular dysfunction in athletes with HRE was found. CONCLUSIONS Based on current evidence, HRE is not a normal finding in athletes. If detected, it should be interpreted as a risk factor for future cardiovascular complications. Future research should address the adequate follow-up and management of athletes with HRE

Detecting Moments of Stress from Measurements of Wearable Physiological Sensors

There is a rich repertoire of methods for stress detection using various physiological signals and algorithms. However, there is still a gap in research efforts moving from laboratory studies to real-world settings. A small number of research has verified when a physiological response is a reaction to an extrinsic stimulus of the participant’s environment in real-world settings. Typically, physiological signals are correlated with the spatial characteristics of the physical environment, supported by video records or interviews. The present research aims to bridge the gap between laboratory settings and real-world field studies by introducing a new algorithm that leverages the capabilities of wearable physiological sensors to detect moments of stress (MOS). We propose a rule-based algorithm based on galvanic skin response and skin temperature, combing empirical findings with expert knowledge to ensure transferability between laboratory settings and real-world field studies. To verify our algorithm, we carried out a laboratory experiment to create a “gold standard” of physiological responses to stressors. We validated the algorithm in real-world field studies using a mixed-method approach by spatially correlating the participant’s perceived stress, geo-located questionnaires, and the corresponding real-world situation from the video. Results show that the algorithm detects MOS with 84% accuracy, showing high correlations between measured (by wearable sensors), reported (by questionnaires and eDiary entries), and recorded (by video) stress events. The urban stressors that were identified in the real-world studies originate from traffic congestion, dangerous driving situations, and crowded areas such as tourist attractions. The presented research can enhance stress detection in real life and may thus foster a better understanding of circumstances that bring about physiological stress in humans

A comparative study on the analysis of hemodynamics in the athlete's heart

The pathophysiological mechanisms underlying the development of the athlete's heart are still poorly understood. To characterize the intracavitary blood flows in the right ventricle (RV) and right-ventricular outflow tract (RVOT) in 2 healthy probands, patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and 2 endurance athletes, we performed 4D-MRI flow measurements to assess differences in kinetic energy and shear stresses. Time evolution of velocity magnitude, mean kinetic energy (MKE), turbulent kinetic energy (TKE) and viscous shear stress (VSS) were measured both along the whole RV and in the RVOT. RVOT regions had higher kinetic energy values and higher shear stresses levels compared to the global averaging over RV among all subjects. Endurance athletes had relatively lower kinetic energy and shear stresses in the RVOT regions compared to both healthy probands and ARVC patients. The athlete's heart is characterized by lower kinetic energy and shear stresses in the RVOT, which might be explained by a higher diastolic compliance of the R

The Impact of Exercise Training and Supplemental Oxygen on Peripheral Muscles in COPD: A Randomized Controlled Trial

Objective: Exercise training is a cornerstone of the treatment of COPD while the related inter-individual heterogeneity in skeletal muscle dysfunction and adaptations are not yet fully understood. We set out to investigate the effects of exercise training and supplemental oxygen on functional and structural peripheral muscle adaptation. Methods: In this prospective, randomized, controlled, double-blind study, 28 patients with non-hypoxemic COPD (FEV1 45.92 ± 9.06%) performed six-weeks of combined endurance and strength training, three times a week while breathing either supplemental oxygen or medical air. The impact on exercise capacity, muscle strength and quadriceps femoris muscle cross-sectional area (CSA), was assessed by maximal cardiopulmonary exercise testing, ten-repetition maximum strength test of knee extension, and magnetic resonance imaging, respectively. Results: After exercise training, patients demonstrated a significant increase of functional capacity, aerobic capacity, exercise tolerance, quadriceps muscle strength and bilateral CSA. Supplemental oxygen affected significantly the training impact on peak work rate when compared to medical air (+0.20 ± 0.03 vs +0.12 ± 0.03 Watt/kg, p = 0.047); a significant increase in CSA (+3.9 ± 1.3 cm2, p = 0.013) was only observed in the training group using oxygen. Supplemental oxygen and exercise induced peripheral desaturation were identified as significant opposing determinants of muscle gain during this exercise training intervention, which led to different adaptations of CSA between the respective subgroups. Conclusions: The heterogenous functional and structural muscle adaptations seem determined by supplemental oxygen and exercise induced hypoxia. Indeed, supplemental oxygen may facilitate muscular training adaptations, particularly in limb muscle dysfunction, thereby contributing to the enhanced training responses on maximal aerobic and functional capacity

Brake response time before and after total knee arthroplasty: a prospective cohort study

<p>Abstract</p> <p>Background</p> <p>Although the numbers of total knee arthroplasty (TKA) are increasing, there is only a small number of studies investigating driving safety after TKA. The parameter 'Brake Response Time (BRT)' is one of the most important criteria for driving safety and was therefore chosen for investigation.</p> <p>The present study was conducted to test the hypotheses that patients with right- or left-sided TKA show a significant increase in BRT from pre-operative (pre-op, 1 day before surgery) to post-operative (post-op, 2 weeks post surgery), and a significant decrease in BRT from post-op to the follow-up investigation (FU, 8 weeks post surgery). Additionally, it was hypothesized that the BRT of patients after TKA is significantly higher than that of healthy controls.</p> <p>Methods</p> <p>31 of 70 consecutive patients (mean age 65.7 +/- 10.2 years) receiving TKA were tested for their BRT pre-op, post-op and at FU. BRT was assessed using a custom-made driving simulator. We used normative BRT data from 31 healthy controls for comparison.</p> <p>Results</p> <p>There were no significant increases between pre-op and post-op BRT values for patients who had undergone left- or right-sided TKA. Even the proportion of patients above a BRT threshold of 700 ms was not significantly increased postop. Controls had a BRT which was significantly better than the BRT of patients with right- or left-sided TKA at all three time points.</p> <p>Conclusion</p> <p>The present study showed a small and insignificant postoperative increase in the BRT of patients who had undergone right- or left-sided TKA. Therefore, we believe it is not justified to impair the patient's quality of social and occupational life post-surgery by imposing restrictions on driving motor vehicles beyond an interval of two weeks after surgery.</p