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ESC Heart Failure Oct 2022Exercise training (ET) has been consistently shown to increase peak oxygen consumption (V̇O ) in patients with heart failure with preserved ejection fraction (HFpEF);... (Clinical Trial)
Clinical Trial
AIMS
Exercise training (ET) has been consistently shown to increase peak oxygen consumption (V̇O ) in patients with heart failure with preserved ejection fraction (HFpEF); however, inter-individual responses vary significantly. Because it is unlikely that ET-induced improvements in peak V̇O are significantly mediated by an increase in peak heart rate (HR), we aimed to investigate whether baseline peak O -pulse (V̇O × HR , reflecting the product of stroke volume and arteriovenous oxygen difference), not baseline peak V̇O , is inversely associated with the change in peak V̇O (adjusted by body weight) following ET versus guideline control (CON) in patients with HFpEF.
METHODS AND RESULTS
This was a secondary analysis of the OptimEx-Clin (Optimizing Exercise Training in Prevention and Treatment of Diastolic Heart Failure, NCT02078947) trial, including all 158 patients with complete baseline and 3 month cardiopulmonary exercise testing measurements (106 ET, 52 CON). Change in peak V̇O (%) was analysed as a function of baseline peak V̇O and its determinants (absolute peak V̇O , peak O -pulse, peak HR, weight, haemoglobin) using robust linear regression analyses. Mediating effects on change in peak V̇O through changes in peak O -pulse, peak HR and weight were analysed by a causal mediation analysis with multiple correlated mediators. Change in submaximal exercise tolerance (V̇O at the ventilatory threshold, VT1) was analysed as a secondary endpoint. Among 158 patients with HFpEF (66% female; mean age, 70 ± 8 years), changes in peak O -pulse explained approximately 72% of the difference in changes in peak V̇O between ET and CON [10.0% (95% CI, 4.1 to 15.9), P = 0.001]. There was a significant interaction between the groups for the influence of baseline peak O -pulse on change in peak V̇O (interaction P = 0.04). In the ET group, every 1 mL/beat higher baseline peak O -pulse was associated with a decreased mean change in peak V̇O of -1.45% (95% CI, -2.30 to -0.60, P = 0.001) compared with a mean change of -0.08% (95% CI, -1.11 to 0.96, P = 0.88) following CON. None of the other factors showed significant interactions with study groups for the change in peak V̇O (P > 0.05). Change in V̇O at VT1 was not associated with any of the investigated factors (P > 0.05).
CONCLUSIONS
In patients with HFpEF, the easily measurable peak O -pulse seems to be a good indicator of the potential for improving peak V̇O through exercise training. While changes in submaximal exercise tolerance were independent of baseline peak O -pulse, patients with high O -pulse may need to use additional therapies to significantly increase peak V̇O .
Topics: Aged; Female; Humans; Male; Middle Aged; Exercise; Heart Failure; Heart Rate; Oxygen; Oxygen Consumption; Stroke Volume
PubMed: 35840541
DOI: 10.1002/ehf2.14070 -
Frontiers in Public Health 2022Quantification of movement intensity and energy utilization, together with frequency of trips, duration, distance, step counts and cadence, is essential for interpreting...
BACKGROUND
Quantification of movement intensity and energy utilization, together with frequency of trips, duration, distance, step counts and cadence, is essential for interpreting the character of habitual walking for transport, and its potential support of health. The purpose of the study is to illuminate this with valid methods and novel perspectives, and to thereby provide a new basis for characterizing and interpreting walking in relation to health outcomes.
METHODS
Habitual middle-aged commuting pedestrians (males = 10, females = 10) were investigated in the laboratory at rest and with maximal treadmill and cycle ergometer tests. Thereafter, levels of oxygen uptake, energy expenditure, ventilation, heart rate, blood lactate, rated perceived exertion, cadence, number of steps, duration, distance, and speed were recorded during the normal walking commute of each participant in Greater Stockholm, Sweden. The number of commutes per week over the year was self-reported.
RESULTS
Walking in the field demanded about 30% more energy per km compared to level treadmill walking. For both sexes, the walking intensity in field was about 46% of maximal oxygen uptake, and energy expenditure amounted to 0.96 kcal · kg · km . The MET values (males: 6.2; females: 6.5) mirrored similar levels of walking speed (males: 5.7; females: 5.9 km · h ) and levels of oxygen uptake (males: 18.6; females: 19.5 mL · kg · min ). The average number of MET-hours per week in a typical month was 22 for males and 20 for females. This resulted in a total weekly energy expenditure of ~1,570 and 1,040 kcal for males and females, respectively. Over the year, the number of walking commutes and their accumulated distance was ~385 trips and 800 km for both sexes.
CONCLUSION
Walking in naturalistic field settings demands its own studies. When males and females walk to work, their relative aerobic intensities and absolute energy demands for a given distance are similar. It is equivalent to the lower part of the moderate relative intensity domain. The combination of oxygen uptake, trip duration and frequency leads to high and sustained levels of MET-hours as well as energy expenditure per week over the year, with a clear health enhancing potential. Based on this study we recommend 6000 transport steps per day, or equivalent, during five weekdays, over the year, in order to reach optimal health gains.
Topics: Middle Aged; Male; Female; Humans; Walking; Energy Metabolism; Heart Rate; Oxygen; Outcome Assessment, Health Care
PubMed: 36339183
DOI: 10.3389/fpubh.2022.911863 -
Journal of Applied Physiology... Aug 2017Diving bradycardia is a primordial oxygen-conserving reflex by which the heart rate of air-breathing vertebrates, including humans, slows down in response to water... (Review)
Review
Diving bradycardia is a primordial oxygen-conserving reflex by which the heart rate of air-breathing vertebrates, including humans, slows down in response to water immersion. Its discovery is attributed to Paul Bert, whose seminal observation was published in 1870 as part of a series of experiments that examined physiological adaptations to asphyxia in ducks and other animals. However, Edmund Goodwyn, a British physician who studied medicine at the University of Edinburgh, had already described this reflex in his doctoral thesis, which was originally published in Latin in 1786 and again in English in 1788. Ironically, even though Goodwyn's work has yet to be recognized in the diving physiology literature, it was referenced in the very publication that contains Bert's original observation. Thus this article brings Goodwyn's work and its historical context to light and argues that he should be credited with the first description of diving bradycardia.
Topics: Animals; Bradycardia; Diving; Heart Rate; Humans; Oxygen; Reflex; Respiration
PubMed: 28495845
DOI: 10.1152/japplphysiol.00221.2017 -
International Journal of Environmental... May 2022Although the marathon race has been democratized, it remains complex due to the famous "hitting the wall" phenomenon after the 25th km. To characterize this "wall" from...
Although the marathon race has been democratized, it remains complex due to the famous "hitting the wall" phenomenon after the 25th km. To characterize this "wall" from a physiological and Rate of Perceived Exertion (RPE) perspective in recreational marathon runners, we report first continuous breath-by-breath gas exchange measurements during an actual marathon race. In order to test the hypothesis that RPE could be a candidate for controlling the marathon pace, this study examined the relationship between RPE and the physiological variables time course throughout a marathon. Only the respiratory frequency and heart rate increased progressively during the race in all the runners, while the oxygen uptake and ventilatory rate followed different kinetics according the individuals. However, the indexation of the physiological parameters and speed by RPE showed the same decreased tendency for all the runners. In conclusion, these results suggest that running a marathon must be self-paced with the RPE.
Topics: Heart Rate; Humans; Marathon Running; Oxygen; Physical Endurance; Physical Exertion
PubMed: 35565153
DOI: 10.3390/ijerph19095760 -
Journal of Applied Physiology... Dec 2019Arterial oxygen tension and oxyhemoglobin saturation () decrease in parallel during hypoxia. Distinguishing between changes in oxygen tension and oxygen content as the...
Arterial oxygen tension and oxyhemoglobin saturation () decrease in parallel during hypoxia. Distinguishing between changes in oxygen tension and oxygen content as the relevant physiological stimulus for cardiorespiratory alterations remains challenging. To overcome this, we recruited nine individuals with hemoglobinopathy manifesting as high-affinity hemoglobin [HAH; partial pressure at 50% (P) = 16 ± 0.4 mmHg] causing greater at a given oxygen partial pressure compared with control subjects ( = 12, P = 26 ± 0.4 mmHg). We assessed ventilatory and cardiovascular responses to acute isocapnic hypoxia, iso-oxic hypercapnia, and 20 min of isocapnic hypoxia (arterial Po = 50 mmHg). Blood gas alterations were achieved with dynamic end-tidal forcing. When expressed as a function of the logarithm of oxygen partial pressure, ventilatory sensitivity to hypoxia was not different between groups. However, there was a significant difference when expressed as a function of . Conversely, the rise in heart rate was blunted in HAH subjects when expressed as a function of partial pressure but similar when expressed as a function of . Ventilatory sensitivity to hypercapnia was not different between groups. During sustained isocapnic hypoxia, the rise in minute ventilation was similar between groups; however, heart rate was significantly greater in the controls during 3 to 9 min of exposure. Our results support the notion that oxygen tension, not content, alters cellular Po in the chemosensors and drives the hypoxic ventilatory response. Our study suggests that in addition to oxygen partial pressure, oxygen content may also influence the heart rate response to hypoxia. We dissociated the effects of oxygen content and pressure of cardiorespiratory regulation studying individuals with high-affinity hemoglobin (HAH). During hypoxia, the ventilatory response, expressed as a function of oxygen tension, was similar between HAH variants and controls; however, the rise in heart rate was blunted in the variants. Our work supports the notion that the hypoxic ventilatory response is regulated by oxygen tension, whereas cardiovascular regulation may be influenced by arterial oxygen content and tension.
Topics: Adult; Blood Gas Analysis; Female; Heart Rate; Humans; Hypercapnia; Hypoxia; Male; Oxygen; Partial Pressure; Respiration
PubMed: 31647724
DOI: 10.1152/japplphysiol.00569.2019 -
European Journal of Applied Physiology Dec 2020Spirulina has previously been reported to improve high-intensity exercise performance and hemoglobin. However, spirulina's effect on arm cycling exercise has yet to be... (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
Spirulina has previously been reported to improve high-intensity exercise performance and hemoglobin. However, spirulina's effect on arm cycling exercise has yet to be investigated. The purpose of this study was to investigate the responses of spirulina supplementation on hemoglobin and on oxygen uptake, RER and HR during seated arm cycling exercise.
METHODS
In a double-blinded randomized crossover design, eleven males untrained in arm cycling ingested 6 g/day of spirulina or placebo for seven days. Seated on the Arm Crank Ergometer, each participant performed a baseline V̇O test, and then after supplementation, 2 × 30-min submaximal exercise bouts corresponding to 55% of their V̇O, followed by an incremental test to fatigue. A seven-day wash-out period was required between conditions. Oxygen uptake, RER and HR were measured continuously during exercise and hemoglobin measured prior to exercise after both conditions.
RESULTS
Spirulina significantly (p < 0.05) increased Hb in comparison to Placebo (144.1 g/l ± 10.5 Vs 154.5 g/l ± 6.9). After spirulina supplementation, during the 30-min exercise bouts, oxygen uptake and HR were significantly lower (2170 ml/min ± 173 Vs 2311 ml/min ± 189 and 154 bpm ± 14 Vs 149 bpm ± 17), RER was not significantly different. In comparison to placebo, Spirulina significantly increased oxygen uptake at time of fatigue (34.10 ml/min/kg ± 6.03 Vs 37.37 ml/min/kg ± 5.98). Time taken to fatigue was not different.
CONCLUSION
Spirulina supplementation significantly reduces oxygen uptake and HR during arm cycling submaximal exercise, allowing for an increased oxygen uptake during an incremental test to fatigue.
Topics: Adult; Arm; Cross-Over Studies; Dietary Supplements; Double-Blind Method; Exercise; Fatigue; Heart Rate; Humans; Male; Oxygen; Oxygen Consumption; Spirulina; Young Adult
PubMed: 32892320
DOI: 10.1007/s00421-020-04487-2 -
Journal of Healthcare Engineering 2022To investigate the important index of maximum oxygen uptake in evaluating cardiopulmonary function and to provide a basis for the evaluation of cardiopulmonary function... (Randomized Controlled Trial)
Randomized Controlled Trial
To investigate the important index of maximum oxygen uptake in evaluating cardiopulmonary function and to provide a basis for the evaluation of cardiopulmonary function for adolescents, a total of 200 healthy adolescents aged 12-14 were selected, and these 200 subjects were randomly assigned to the modeling group and the test group. In the first stage, data of 150 subjects were randomly selected, and the regression equation for VO2max was established by adding independent variables such as gender, age, height, weight, body mass index, and resting heart rate. In the second stage, the remaining 50 subjects were selected as the test group to test and evaluate the prediction effect of the prediction model. The results showed that the correlation coefficient between the measured value of maximal oxygen uptake and the predicted value was 0.983, and the significance level was 0.000, which was significantly lower than 0.01 correlation, indicating that there was an obvious concomitant relationship between the two values. The maximum oxygen uptake calculated by this equation is good and has a good application prospect.
Topics: Adolescent; Exercise; Exercise Test; Heart Rate; Humans; Oxygen; Oxygen Consumption; Respiration
PubMed: 35310194
DOI: 10.1155/2022/5961197 -
The Journal of Extra-corporeal... Dec 2007Since the introduction of cardiopulmonary bypass, clinicians have tried to define the optimal blood flow for a given patient. The difficulty in determining a correct... (Review)
Review
Since the introduction of cardiopulmonary bypass, clinicians have tried to define the optimal blood flow for a given patient. The difficulty in determining a correct blood flow lies in the fact that cardiac surgery is done in a very inhomogeneous population, from neonates to the octogenarian, and often under non-physiologic conditions (hypothermia, hemodilution, low flow, etc.). Although clinicians acknowledge that maintaining a minimum oxygen delivery is more meaningful than using a fixed flow rate based on the metabolic needs of awake resting volunteers, the latter is most used in clinical practice. This is explained by the fact that no values are available on critical oxygen delivery for adequate tissue oxygenation under a given clinical condition. This was an overview of the relevant literature. In most centers, perfusionists use in-line monitoring, such as venous saturation or venous blood gases, for estimation of adequacy of tissue perfusion. Unfortunately, these oxygen-derived parameters have a poor correlation with anaerobic energy supply. Measurement of intermittent whole blood lactate concentration is used to compensate for this poor relationship, but as it monitors the concentration at given time points, it precludes optimally timely intervention by the perfusionist. The physiologic buffering by bicarbonate of the acid generated by converting pyruvate into lactate will produce carbon dioxide. As a consequence, carbon dioxide-derived parameters do have a good correlation with inadequate tissue perfusion. In-line monitoring of carbon dioxide production gives real-time information on tissue perfusion. Use of a standard reference flow for each patient is a poor option, because it does not reflect the metabolic need of the patient. Oxygen-derived parameters, such as venous saturation or partial venous oxygen tension, are poor predictors of anaerobic metabolism. A combination of intermittent whole blood lactate measurement with carbon dioxide-derived parameters predicts anaerobic energy production and allows proactive intervention by the perfusionist.
Topics: Anaerobiosis; Carbon Dioxide; Cardiac Output; Cardiopulmonary Bypass; Extracorporeal Membrane Oxygenation; Humans; Oxygenators, Membrane; Perfusion; Thoracic Surgery
PubMed: 18293819
DOI: No ID Found -
The Turkish Journal of Gastroenterology... Dec 2006We aimed to investigate whether endoscopy or midazolam as premedication causes oxygen desaturation and to determine factors which may affect the occurrence of oxygen... (Clinical Trial)
Clinical Trial
BACKGROUND/AIMS
We aimed to investigate whether endoscopy or midazolam as premedication causes oxygen desaturation and to determine factors which may affect the occurrence of oxygen desaturation.
METHODS
Totally 200 patients with various indications (103 men and 97 women), who presented to the Endoscopy Unit of Dicle University Hospital for upper gastrointestinal endoscopy examination, were included in the study. Anamnesis and anthropometric values of the patients were taken. Preoperative oxygen saturation, hemoglobin levels and heart rate per minute were recorded. Patients with initial oxygen saturation levels <90% were excluded. Patients were divided into two groups. The first group included 100 patients who underwent endoscopic examination without sedation and the second group included 100 patients who underwent endoscopic examination with sedation [midazolam (2-5 mg)]. At the end of endoscopy, intravenous flumazenil (0.2 mg) was administered to the premedication patients. Patients were monitored for oxygen saturation and heart rate starting before the sedation and oropharynx anesthesia and lasting until 1 min after the end of the procedure. During the endoscopic examination, minimum oxygen saturation and maximum heart rate values were recorded. The duration of the oxygen saturation <90% was recorded throughout the procedure and the relation of this time with the total time of the endoscopic examination was evaluated.
RESULTS
The mean age of the 200 patients included in the study was 45 and 44 years for Group 1 and Group 2, respectively. No differences were found between the two groups in terms of body mass index, smoking, hemoglobin and basal maximum pulse rate, duration of endoscopy, minimum basal oxygen saturation, duration of hypoxia and time to hypoxia. No relation was determined between oxygen desaturation and gender, duration of the endoscopy, basal pulse rate or hemoglobin level. It was found that smoking made significant contributions to the oxygen desaturation.
CONCLUSION
Midazolam premedication for upper gastrointestinal system endoscopy is a reliable procedure and does not contribute an additional risk in individuals without serious comorbidities. Smoking habits should be taken into account in endoscopy patients.
Topics: Adult; Aged; Endoscopy, Gastrointestinal; Female; Heart Rate; Hemoglobins; Humans; Hypnotics and Sedatives; Male; Midazolam; Middle Aged; Oximetry; Oxygen; Risk Factors; Smoking
PubMed: 17205406
DOI: No ID Found -
European Journal of Clinical... Mar 2021This study aimed to investigate the value of high-flow nasal cannula (HNFC) oxygen therapy in treating patients with severe novel coronavirus pneumonia (COVID-19). (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
This study aimed to investigate the value of high-flow nasal cannula (HNFC) oxygen therapy in treating patients with severe novel coronavirus pneumonia (COVID-19).
METHODS
The clinical data of 22 patients with severe COVID-19 were collected. The heart rate (HR), respiratory rate (RR) and oxygenation index (PO /FiO ) at 0, 6, 24 and 72 hours after treatment were compared between the HFNC oxygen therapy group and the conventional oxygen therapy (COT) group. In addition, the white blood cell (WBC) count, lymphocyte (L) count, C-reactive protein (CRP) and procalcitonin (PCT) were compared before and at 72 hours after oxygen therapy treatment.
RESULTS
The differences at 0 hours between the two groups were not statistically significant. Compared with COT group,in the HFNC oxygen therapy group, HR, RR and PaO /FiO were better at 6 hours after treatment, PaO /FiO was better at 24 and 72 hours. After 72 hours, L and CRP had improved in the HFNC oxygen therapy group compared with the COT group, but the differences in WBC and PCT were not statistically significant. The length of stay in the intensive care unit (ICU) and the total length of hospitalization was shorter in the HFNC oxygen therapy group than in the COT group.
CONCLUSION
Compared with COT, early application of HFNC oxygen therapy in patients with severe COVID-19 can improve oxygenation and RR, and HFNC oxygen therapy can improve the infection indexes of patients and reduce the length of stay in the ICU of patients. Therefore, it has high clinical application value.
Topics: Blood Gas Analysis; C-Reactive Protein; COVID-19; Cannula; Female; Heart Rate; Humans; Intensive Care Units; Length of Stay; Leukocyte Count; Lymphocyte Count; Male; Middle Aged; Oxygen; Oxygen Inhalation Therapy; Partial Pressure; Procalcitonin; Respiratory Rate; SARS-CoV-2; Severity of Illness Index
PubMed: 33068293
DOI: 10.1111/eci.13435