Respiratory muscle strength pre- and post-maximal apneas in a world champion breath-hold diver.

Maximal static dry, that is, on land, apneas (breath-holds) result in severe hypoxemia and hypercapnia and have easy-going and struggle phases. During the struggle phase, the respiratory muscles involuntarily contract against the closed glottis in increasing frequency and magnitude, that is, involuntary breathing movements (IBMs). IBMs during maximal static apnea have been suggested to fatigue respiratory muscles, but this has yet to be measured.

Consequences of Preterm Birth: Knowns, Unknowns, and Barriers to Advancing Cardiopulmonary Health.

Preterm birth occurs in 10% of all live births and creates challenges to neonatal life, which persist into adulthood. Significant previous work has been undertaken to characterize and understand the respiratory and cardiovascular sequelae of preterm birth, which are present in adulthood, i.e.

Hyperoxia-induced stepwise reduction in blood flow through intrapulmonary, but not intracardiac, shunt during exercise.

Blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) () increases during exercise breathing air, but it has been proposed that is reduced during exercise while breathing a fraction of inspired oxygen ([Formula: see text]) of 1.00. It has been argued that the reduction in saline contrast bubbles through IPAVA is due to altered in vivo microbubble dynamics with hyperoxia reducing bubble stability, rather than closure of IPAVA.

A Systematic Review of Methods Used to Determine the Work of Breathing during Exercise.

Introduction: Measurement of the work of breathing (Wb) during exercise provides useful insights into the energetics and mechanics of the respiratory muscles across a wide range of minute ventilations. The methods and analytical procedures used to calculate the Wb during exercise have yet to be critically appraised in the literature.

Purpose: The aim of this systematic review was to evaluate the quality of methods used to measure the Wb during exercise in the available literature.

Blunted hypoxic pulmonary vasoconstriction in apnoea divers.

New Findings: What is the central question of this study? Does the hyperbaric, hypercapnic, acidotic, hypoxic stress of apnoea diving lead to greater pulmonary vasoreactivity and increased right heart work in apnoea divers? What is the main finding and its importance? Compared with sex- and age-matched control subjects, divers experienced significantly less change in total pulmonary resistance in response to short-duration isocapnic hypoxia. With oral sildenafil (50 mg), there were no differences in total pulmonary resistance between groups, suggesting that divers can maintain normal pulmonary artery tone in hypoxic conditions. Blunted hypoxic pulmonary vasoconstriction might be beneficial during apnoea diving.

High prevalence of patent foramen ovale in recreational to elite breath hold divers.

Objectives: During apnea diving, a patent foramen ovale may function as a pressure relief valve under conditions of high pulmonary pressure, preserving left-ventricular output. Patent foramen ovale prevalence in apneic divers has not been previously reported. We aimed to determine the prevalence of patent foramen ovale in apneic divers compared to non-divers.

Lower transfer factor of the lung for carbon monoxide in women with a patent foramen ovale.

New Findings: What is the central question of this study? Do individuals with a patent foramen ovale (PFO ) have a lower lung transfer factor for carbon monoxide than those without (PFO )? What is the main finding and its importance? We found a lower rate constant for carbon monoxide uptake in PFO compared with PFO women, which was physiologically relevant (≥0.5 z-score difference), but not for PFO versus PFO men. This suggests that factors independent of the PFO are responsible for our findings, possibly inherent structural differences in the lung.

Physiological aspects of cardiopulmonary dysanapsis on exercise in adults born preterm.

Progressive improvements in perinatal care and respiratory management of preterm infants have resulted in increased survival of newborns of extremely low gestational age over the past few decades. However, the incidence of bronchopulmonary dysplasia, the chronic lung disease after preterm birth, has not changed. Studies of the long-term follow-up of adults born preterm have shown persistent abnormalities of respiratory, cardiovascular and cardiopulmonary function, possibly leading to a lower exercise capacity.

No effect of patent foramen ovale on acute mountain sickness and pulmonary pressure in normobaric hypoxia.

New Findings: What is the central question to this study? Is there a relationship between a patent foramen ovale and the development of acute mountain sickness and an exaggerated increase in pulmonary pressure in response to 7-10 h of normobaric hypoxia? What is the main finding and its importance? Patent foramen ovale presence did not increase susceptibility to acute mountain sickness or result in an exaggerated increase in pulmonary artery systolic pressure with normobaric hypoxia. This suggests hypobaric hypoxia is integral to the increased susceptibility to acute mountain sickness previously reported in those with patent foramen ovale, and patent foramen ovale presence alone does not contribute to the hypoxic pulmonary pressor response.

Abstract: Acute mountain sickness (AMS) develops following rapid ascent to altitude, but its exact causes remain unknown.

A comparison of methods used to quantify the work of breathing during exercise.

The mechanical work of breathing (Wb) is an insightful tool used to assess respiratory mechanics during exercise. There are several different methods used to calculate the Wb, however, each approach having its own distinct advantages/disadvantages. To date, a comprehensive assessment of the differences in the components of Wb between these methods is lacking.

The effect of estimating chest wall compliance on the work of breathing during exercise as determined via the modified Campbell diagram.

The modified Campbell diagram provides one of the most comprehensive assessments of the work of breathing (Wb) during exercise, wherein the resistive and elastic work of inspiration and expiration are quantified. Importantly, a necessary step in constructing the modified Campbell diagram is to obtain a value for chest wall compliance (C). To date, it remains unknown whether estimating or directly measuring C impacts the Wb, as determined by the modified Campbell diagram.

Respiratory and cardiopulmonary limitations to aerobic exercise capacity in adults born preterm.

Adults born preterm, regardless of whether they develop bronchopulmonary dysplasia, have underdeveloped respiratory and cardiopulmonary systems. The resulting impaired respiratory and cardiopulmonary systems are inadequate for the challenges imposed by aerobic exercise, which is exacerbated by the presence of bronchopulmonary dysplasia. Thus the respiratory and cardiopulmonary systems of these preterm individuals may be the most influential contributors to the significantly lower aerobic exercise capacity compared with their term born counterparts.

Impaired pulmonary gas exchange efficiency, but normal pulmonary artery pressure increases, with hypoxia in men and women with a patent foramen ovale.

New Findings: What is the central question of this study? Do individuals with a patent foramen ovale (PFO ) have a larger alveolar-to-arterial difference in ( ) than those without (PFO ) and/or an exaggerated increase in pulmonary artery systolic pressure (PASP) in response to hypoxia? What is the main finding and its importance? PFO had a greater while breathing air, 16% and 14% O , but not 12% or 10% O . PASP increased equally in hypoxia between PFO and PFO . These data suggest that PFO may not have an exaggerated acute increase in PASP in response to hypoxia.

Thoracic gas compression during forced expiration is greater in men than women.

Intrapleural pressure during a forced vital capacity (VC) maneuver is often in excess of that required to generate maximal expiratory airflow. This excess pressure compresses alveolar gas (i.e.

Analysis of maximal expiratory flow-volume curves in adult survivors of preterm birth.

Adult survivors of very preterm (≤32 wk gestational age) birth without (PRE) and with bronchopulmonary dysplasia (BPD) have variable degrees of airflow obstruction at rest. Assessment of the shape of the maximal expiratory flow-volume (MEFV) curve in PRE and BPD may provide information concerning their unique pattern of airflow obstruction. The purposes of the present study were to ) quantitatively assess the shape of the MEFV curve in PRE, BPD, and healthy adults born at full-term (CON), ) identify where along the MEFV curve differences in shape existed between groups, and ) determine the association between an index of MEFV curve shape and characteristics of preterm birth (i.

Increased Sleep Disturbances and Pain in Veterans With Comorbid Traumatic Brain Injury and Posttraumatic Stress Disorder.

Study Objectives: Veterans are at an increased risk for traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD), both of which are associated with sleep disturbances and increased pain. Furthermore, sleep disturbances and pain are reciprocally related such that each can exacerbate the other. Although both TBI and PTSD are independently linked to sleep disturbances and pain, it remains unclear whether Veterans with comorbid TBI+PTSD show worse sleep disturbances and pain compared to those with only TBI or PTSD.

Alleviating mechanical constraints to ventilation with heliox improves exercise endurance in adult survivors of very preterm birth.

Adult survivors of very preterm birth (PRET) have significantly lower aerobic exercise capacities than their counterparts born at term (CONT), but the underlying cause is unknown. To test whether expiratory flow limitation (EFL) during exercise negatively affects exercise endurance in PRET, we had PRET and CONT exercise to exhaustion breathing air and again breathing heliox. In PRET, EFL decreased and time-to-exhaustion increased significantly while breathing heliox.

Premature birth affects the degree of airway dysanapsis and mechanical ventilatory constraints.

What is the central question of this study? Adult survivors of preterm birth without (PRE) and with bronchopulmonary dysplasia (BPD) have airflow obstruction at rest and significant mechanical ventilatory constraints during exercise compared with those born at full term (CON). Do PRE/BPD have smaller airways, indexed via the dysanapsis ratio, than CON? What is the main finding and its importance? The dysanapsis ratio was significantly smaller in BPD and PRE compared with CON, with BPD having the smallest dysanapsis ratio. These data suggest that airflow obstruction in PRE and BPD might be because of smaller airways than CON.