Evidence for sustained physiological adaptation between consecutive exercise bouts at simulated altitude.

Intermittent hypoxia has been used to enhance oxygen delivery in athletes and patients; however, it is unclear whether acute exposure is sufficient to elicit lasting physiologic adaptation(s). The purpose of this study was to evaluate physiologic response(s) to hypobaric-hypoxic (HH) exercise. Nine participants (4 M/5F; 37.

Positive pressure ventilation improves oxygen saturation at altitude during recreational aviation: A pilot study.

We investigated whether a commercial bi-level positive airway pressure (BPAP) device, would improve peripheral oxygen saturation (SpO) during recreational aviation up to 12,500 feet without supplemental oxygen. Ten adults with recreational flight experience (age:47 ± 14; female = 5) completed a standardized flight profile in an unpressurised aircraft, involving randomized crossover design at 8,000 feet and 12,500 feet with BPAP or control. SpO, middle cerebral artery velocity (MCAv), heart rate (HR), respiratory rate (RR), and relative tidal volume (TV) index were measured continuously.

Health Risks of Asphalt Emission: State-of-the-Art Advances and Research Gaps.

Asphalt-related emissions pose significant health risks due to the release of volatile organic compounds (VOCs) that affect both workers in construction and the general public. Even at low concentrations, certain VOCs are highly toxic, with some of their metabolic byproducts, such as epoxides, known to cause DNA damage, oxidative stress, and other genetic alterations. The health implications are particularly concerning given that these emissions are persistent, and exposure can occur over prolonged periods, especially in urban areas where asphalt is prevalent.

Evaluation of phrenic nerve stimulation trigger lag and synchronization in different modes of ventilation.

Phrenic nerve stimulation is currently being investigated for the prevention of diaphragm atrophy in patients with mechanically supported breathing. Patients receiving breathing support from mechanical ventilation are at risk of mismatches between respiratory demand and ventilator support. Our objectives were to determine if a novel phrenic nerve stimulation device provided stimulation during inspiration as intended and did not exacerbate any potential discordances.

Expiratory Threshold Loading and Attentional Performance.

While there are numerous factors that may affect pilot attentional performance, we hypothesize that an increased expiratory work of breathing experienced by fighter pilots may impose a "distraction stimulus" by creating an increased expiratory effort sensation. Therefore, the purpose of this study was to determine the extent to which increasing expiratory pressure time product or expiratory effort sensation impacts attentional performance. Data was collected on 10 healthy participants (age: 29 ± 6 yr).

Blunted cardiovascular responses to exercise by inhibiting afferent feedback via spinal cord stimulation in heart failure.

This case study investigated the impact of SCS on alterations in blood pressure during constant-load exercise in a female patient with heart failure. Three different SCS frequencies [No SCS (~0 Hz), Low SCS (~100 Hz), and High SCS (~1000 Hz)] with and without ischaemic stimulation of the legs (cuffs) were randomly applied during constant-load exercise. To determine cardiovascular and ventilatory responses to exercise following SCS frequencies, BP, heart rate (HR), and respiratory gas exchange were measured.

Effect of Ultramarathon Trail Running at Sea Level and Altitude on Alveolar-Capillary Function and Lung Diffusion.

Introduction: Endurance exercise at altitude can increase cardiac output and pulmonary vascular pressure to levels that may exceed the stress tolerability of the alveolar-capillary unit. This study examined the effect of ultramarathon trail racing at different altitudes (ranging from <1000 m to between 1500 and 2700 m) on alveolar-capillary recruitment and lung diffusion.

Methods: Cardiac and lung function were examined before and after an ultramarathon in 67 runners (age: 41 ± 9 yr, body mass index: 23 ± 2 kg·m -2 , 10 females), and following 12-24 h of recovery in a subset ( n = 27).

The correlation between carotid artery Doppler and stroke volume during central blood volume loss and resuscitation.

Background: Using peripheral arteries to infer central hemodynamics is common among hemodynamic monitors. Doppler ultrasound of the common carotid artery has been used in this manner with conflicting results. We investigated the relationship between changing common carotid artery Doppler measures and stroke volume (SV), hypothesizing that more consecutively-averaged cardiac cycles would improve SV-carotid Doppler correlation.

Metabolic insights at the finish line: deciphering physiological changes in ultramarathon runners through breath VOC analysis.

Exhaustive exercise can induce unique physiological responses in the lungs and other parts of the human body. The volatile organic compounds (VOCs) in exhaled breath are ideal for studying the effects of exhaustive exercise on the lungs due to the proximity of the breath matrix to the respiratory tract. As breath VOCs can originate from the bloodstream, changes in abundance should also indicate broader physiological effects of exhaustive exercise on the body.

The Correlation between Carotid Artery Corrected Flow Time and Velocity Time Integral during Central Blood Volume Loss and Resuscitation.

Background: Doppler ultrasound of the common carotid artery is used to infer central hemodynamics. For example, change in the common carotid artery corrected flow time (ccFT) and velocity time integral (VTI) are proposed surrogates of changing stroke volume. However, conflicting data exist which may be due to inadequate beat sample size and measurement variability - both intrinsic to handheld systems.

Reproducibility and responsiveness of airway impedance measures derived from the forced oscillation technique across different operating lung volumes.

Background: The forced oscillation technique (FOT) enables non-invasive measurement of respiratory system impedance. Limited data exists on how changes in operating lung volume (OLV) impact FOT-derived measures of airway resistance (Rrs) and reactance (Xrs).

Objectives: This study examined the reproducibility and responsiveness of FOT-derived measures of Rrs and Xrs during simulated changes in OLV.

Feasibility of Noninvasive Assessment of Cardiac Output during Exercise in Healthy Adults by a Novel Elaboration on Systolic Time Intervals.

Background: Although assessment of cardiovascular hemodynamics during exercise can provide clinical insights, it is challenging to acquire it in clinical settings.

Objectives: Accordingly, this preliminary study was to determine whether a novel elaboration on systolic time interval measures (eSTICO) method of quantifying cardiac output and stroke volume was comparable to those obtained using a validated soluble gas (open circuit CO measure [OpCircCO]) method or calculation based on oxygen consumption (oxygen consumption-based CO [VO2CO]) during exercise.

Methods: For the present study, 14 healthy subjects (male: n = 12, female: n = 2) performed incremental exercise on a recumbent cycle ergometer.

Semi-supervised exercise training program more effective for individuals with postural orthostatic tachycardia syndrome in randomized controlled trial.

Purpose: Exercise like any medication requires the correct dose; to be effective the appropriate frequency, duration, and intensity are necessary. This study aimed to assess if a semi-supervised exercise training (ET) program would be more effective at improving aerobic fitness (VO), exercise tolerance, and symptoms in individuals with postural orthostatic tachycardia syndrome (POTS) compared to the standard of care (SOC).

Methods: Subjects were randomized to either the ET or SOC groups (n 26 vs.

Alterations in pulmonary vasomotor modulators post aerobic exercise training in non-alcoholic fatty liver disease.

This study investigated the impact of exercise training on major pulmonary vasomotor mediators and receptors including endothelial nitric oxide synthase (eNOS) inducible NOS (iNOS), endothelin-1 (ET-1), ET-1 receptors A (ET) and-B (ET) in high-fat-high-carbohydrate (HFHC) induced non-alcoholic fatty liver disease (NAFLD). NAFLD increased iNOS, ET-1 and ET (p < 0.05) but not ET (p > 0.

Pulmonary Capillary Recruitment Is Attenuated Post Left Ventricular Assist Device Implantation.

There is limited knowledge of pulmonary physiology and pulmonary function after continuous flow-left ventricular assist device (CF-LVAD) implantation. Therefore, this study investigated whether CF-LVAD influenced pulmonary circulation by assessing pulmonary capillary blood volume and alveolar-capillary conductance in addition to pulmonary function in patients with heart failure. Seventeen patients with severe heart failure who were scheduled for CF-LVAD implantation (HeartMate II, III, Abbott, Abbott Park, IL or Heart Ware, Medtronic, Minneapolis, MN) participated in the study.

A Novel Spectral Index for Tracking Preload Change from a Wireless, Wearable Doppler Ultrasound.

A wireless, wearable Doppler ultrasound offers a new paradigm for linking physiology to resuscitation medicine. To this end, the image analysis of simultaneously-acquired venous and arterial Doppler spectrograms attained by wearable ultrasound represents a new source of hemodynamic data. Previous investigators have reported a direct relationship between the central venous pressure (CVP) and the ratio of the internal jugular-to-common carotid artery diameters.

Rate-Adaptive Atrial Pacing for Heart Failure With Preserved Ejection Fraction: The RAPID-HF Randomized Clinical Trial.

Importance: Reduced heart rate during exercise is common and associated with impaired aerobic capacity in heart failure with preserved ejection fraction (HFpEF), but it remains unknown if restoring exertional heart rate through atrial pacing would be beneficial.

Objective: To determine if implanting and programming a pacemaker for rate-adaptive atrial pacing would improve exercise performance in patients with HFpEF and chronotropic incompetence.

Design, Setting, And Participants: Single-center, double-blind, randomized, crossover trial testing the effects of rate-adaptive atrial pacing in patients with symptomatic HFpEF and chronotropic incompetence at a tertiary referral center (Mayo Clinic) in Rochester, Minnesota.

Influence of rapidly oscillating inspired O and N concentrations on pulmonary vascular function and lung fluid balance in healthy adults.

Aircrew may experience rapidly oscillating inspired O2/N2 ratios owing to fluctuations in the on-board oxygen delivery systems (OBOG). Recent investigations suggest these oscillations may contribute to the constellation of physiologic events in aircrew of high-performance aircraft. Therefore, the purpose of this study was to determine whether these "operationally-relevant" environmental challenges may cause decrements in measures of pulmonary vascular physiology.

The Utility of High Intensity Interval Training to Improve Cognitive Aging in Heart Disease Patients.

Adults with cardiovascular disease and heart failure are at higher risk of cognitive decline. Cerebral hypoperfusion appears to be a significant contributor, which can result from vascular dysfunction and impairment of cerebral blood flow regulation. In contrast, higher cardiorespiratory fitness shows protection against brain atrophy, reductions in cerebral blood flow, and cognitive decline.

Feasibility of Brachial Occlusion Technique for Beat-to-Beat Pulse Wave Analysis.

Czech physiologist Penaz tried to overcome limitations of invasive pulse-contour methods (PCM) in clinical applications by a non-invasive method (finger mounted BP cuff) for continuous arterial waveform detection and beat-to-beat analysis. This discovery resulted in significant interest in human physiology and non-invasive examination of hemodynamic parameters, however has limitations because of the distal BP recording using a volume-clamp method. Thus, we propose a validation of beat-to-beat signal analysis acquired by novel a brachial occlusion-cuff (suprasystolic) principle and signal obtained from Finapres during a forced expiratory effort against an obstructed airway (Valsalva maneuver).