Partitioning the work of breathing during running and cycling using optoelectronic plethysmography

2021 ◽  
Author(s):  
Shalaya Kipp ◽  
Michael G. Leahy ◽  
Jacob A. Hanna ◽  
Andrew William Sheel
Keyword(s):  
Maximal Exercise ◽  
Work Of Breathing ◽  
Respiratory Muscles ◽  
Quantitative Measure ◽  
Mechanical Work ◽  
Abdominal Muscles ◽  
Relative Contribution ◽  
Balloon Catheters ◽  
Optoelectronic Plethysmography ◽  
Work Done

Work of breathing (Wb) derived from a single lung volume and pleural pressure is limited and does not fully characterize the mechanical work done by the respiratory musculature. It has long been known abdominal activation increases with increasing exercise intensity, yet the mechanical work done by these muscles is not reflected in Wb. Using Optoelectronic plethysmography (OEP) we sought to show first, the volumes obtained from OEP (VCW) were comparable to volumes obtained from flow integration (Vt) during cycling and running, and second, to show partitioned volume from OEP could be utilized to quantify the mechanical work done by the ribcage (WBRC) and abdomen (WBAB) during exercise. We fit 11 subjects (6 males/ 5 females) with reflective markers and balloon catheters. Subjects completed an incremental ramp cycling test to exhaustion and a series of submaximal running trials. We found good agreement between VCW vs Vt during cycling (p>0.05) and running (p>0.05). From rest to maximal-exercise, WBAB increased by 84% (range: 30 - 99%;WBAB: 1 ± 1 J/min to 61 ± 52 J/min). The relative contribution of the abdomen increased from 17 ± 9% at rest to 26 ± 16% during maximal-exercise. Our study highlights and provides a quantitative measure of the role of the abdominal muscles during exercise. Incorporating the work done by the abdomen allows for a greater understanding of the mechanical tasks required by the respiratory muscles and could provide further insight into how the respiratory system functions during disease and injury.

scholarly journals Adaptation of lung, chest wall, and respiratory muscles during pregnancy: preparing for birth

2019 ◽  
Vol 127 (6) ◽  
pp. 1640-1650 ◽  
Author(s):  
Antonella LoMauro ◽  
Andrea Aliverti ◽  
Peter Frykholm ◽  
Daniela Alberico ◽  
Nicola Persico ◽  
...  
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Respiratory Muscles ◽  
Active Role ◽  
Normal Pregnancy ◽  
Abdominal Muscles ◽  
Noninvasive Methods ◽  
Rib Cage ◽  
Optoelectronic Plethysmography ◽  
Noninvasive Analysis

A plethora of physiological and biochemical changes occur during normal pregnancy. The changes in the respiratory system have not been as well elucidated, in part because radioimaging is usually avoided during pregnancy. We aimed to use several noninvasive methods to characterize the adaptation of the respiratory system during the full course of pregnancy in preparation for childbirth. Eighteen otherwise healthy women (32.3 ± 2.8 yr) were recruited during early pregnancy. Spirometry, optoelectronic plethysmography, and ultrasonography were used to study changes in chest wall geometry, breathing pattern, lung and thoraco-abdominal volume variations, and diaphragmatic thickness in the first, second, and third trimesters. A group of nonpregnant women were used as control subjects. During the course of pregnancy, we observed a reorganization of rib cage geometry, in shape but not in volume. Despite the growing uterus, there was no lung restriction (forced vital capacity: 101 ± 15% predicted), but we did observe reduced rib cage expansion. Breathing frequency and diaphragmatic contribution to tidal volume and inspiratory capacity increased. Diaphragm thickness was maintained (1st trimester: 2.7 ± 0.8 mm, 3rd trimester: 2.5 ± 0.9 mm; P = 0.187), possibly indicating a conditioning effect to compensate for the effects of the growing uterus. We conclude that pregnancy preserved lung volumes, abdominal muscles, and the diaphragm at the expense of rib cage muscles. NEW & NOTEWORTHY Noninvasive analysis of the kinematics of the chest wall and the diaphragm during resting conditions in pregnant women revealed significant changes in the pattern of thoracoabdominal breathing across the trimesters. That is, concomitant with the progressive changes of chest wall shape, the diaphragm increased its contribution to both spontaneous and maximal breathing, maintaining its thickness despite its lengthening due to the growing uterus. These results suggest that during pregnancy the diaphragm is conditioned to optimize its active role provided during parturition.

Physiological changes and compensatory mechanisms by the action of respiratory muscles in a porcine model of phrenic nerve injury

2021 ◽  
Author(s):  
Antonella LoMauro ◽  
Andrea Aliverti ◽  
Gaetano Perchiazzi ◽  
Peter Frykholm
Keyword(s):  
Pressure Support Ventilation ◽  
Phrenic Nerve ◽  
Pressure Support ◽  
Work Of Breathing ◽  
Respiratory Muscles ◽  
Nerve Damage ◽  
Diaphragmatic Paralysis ◽  
Spontaneous Respiration ◽  
Abdominal Muscles ◽  
Support Ventilation

Phrenic nerve damage may occur as a complication of specific surgical procedures, prolonged mechanical ventilation, or physical trauma. The consequent diaphragmatic paralysis or dysfunction can lead to major complications. To elucidate the role of the non-diaphragmatic respiratory muscles during partial or complete diaphragm paralysis induced by unilateral and bilateral phrenic nerve damage at different levels of ventilatory pressure support in an animal model. Ten pigs were instrumented, the phrenic nerve exposed from the neck and spontaneous respiration preserved at three levels of pressure support: high, low and null at baseline condition, after left phrenic nerve damage and bilateral phrenic nerve damage. Breathing pattern, thoraco-abdominal volumes and asynchrony and pressures were measured at each condition. Physiological breathing was predominantly diaphragmatic, homogeneously distributed between right and left sides. After unilateral damage, the paralyzed hemidiaphragm was passively dragged by the ipsilateral ribcage muscles and the contralateral hemidiaphragm. After bilateral damage, the drive to and the work of breathing of ribcage and abdominal muscles increased, to compensate for diaphragmatic paralysis, ensuing paradoxical thoraco-abdominal breathing. Increasing level of pressure support ventilation replaces this muscle group compensation. When the diaphragm is paralyzed (unilaterally and/or bilaterally), there is a coordinated reorganization of non-diaphragmatic respiratory muscles as compensation that might be obscured by high level of pressure support ventilation. Non-invasive thoraco-abdominal volume and asynchrony assessment could be useful in phrenic nerve injured patients to estimate the extent and type of inspiratory muscle dysfunction.

Mechanical work of breathing during muscular exercise

1960 ◽  
Vol 15 (3) ◽  
pp. 354-358 ◽  
Author(s):  
R. Margaria ◽  
G. Milic-Emili ◽  
J. M. Petit ◽  
G. Cavagna
Keyword(s):  
Energy Cost ◽  
Work Of Breathing ◽  
Pulmonary Ventilation ◽  
Respiratory Muscles ◽  
Mechanical Efficiency ◽  
Mechanical Work ◽  
Muscular Exercise ◽  
Additional Energy ◽  
External Work ◽  
Small Magnitude

The mechanical work of breathing was measured during muscular exercise on three normal subjects from simultaneous records of intra-esophageal pressure and tidal volume. At the maximal values of ventilation attained during exercise, the mechanical work of breathing amounts to about 100–120 cal/min. The maximum pulmonary ventilation useful for external work is attained when the energy cost of breathing due to any additional unit of air ventilated (dWre/dV) equals the additional energy provided by the same change in ventilation (dWtot/ dV), i.e. when dWre/dV = dWtot/dV. The maximal values of ventilation obtained experimentally during muscular exercise are in good agreement with that assumption, if the mechanical efficiency of the respiratory muscles is taken as 0.25. This implies that the mechanical efficiency of the respiratory muscles is the same as that of the muscles involved in performing useful external work. The work of breathing is of relatively small magnitude: during exercise the work of a breathing cycle amounts, at maximum, to 8% of the maximum potential work of breathing, calculated from the pressure-volume diagram of the respiratory apparatus, and the energy cost of respiration represents no more than 3% of the total energy consumed by the subject. Submitted on May 21, 1959

Mechanical work of breathing derived from rib cage and abdominal V-P partitioning

1976 ◽  
Vol 41 (5) ◽  
pp. 752-763 ◽  
Author(s):  
M. D. Goldman ◽  
G. Grimby ◽  
J. Mead
Keyword(s):  
Chest Wall ◽  
Work Of Breathing ◽  
Mechanical Work ◽  
Quiet Breathing ◽  
Campbell Diagram ◽  
Rib Cage ◽  
Abdominal Musculature ◽  
Work Done ◽  
Inspiratory Work

Estimates of the mechanical work of breathing derived from measurements of separate rib cage and abdominal volume displacements, each plotted against transthoracic pressure, include the elastic cost of chest wall distortion which may occur during breathing. Inspiratory work is partitioned between the diaphragm and the rib cage musculature by adding measurements of transabdominal pressure. The mechanical work of breathing derived from separate rib cage and abdominal volume-pressure (V-P) tracings (the sum of work done by the diaphragm, rib cage, and abdominal musculature) is compared with ventilatory work estimated from the Campbell diagram (which does not include any distortional work). During resting breathing the two estimates are closely comparable, consistent with little or no distortion of the chest wall during quiet breathing. As ventilation increases, the estimate developed from rib cage and abdominal tracings reveals systematically greater mechanical work than is estimated from the Campbell diagram, consistent with distortion of the chest wall from the relaxed thoracoabdominal configuration at higher levels of ventilation. At ventilations achieved during exercise, the Campbell diagram may underestimate the work of breathing by up to 25%.

Relationships between stimulus and work of breathing at different lung volumes

1962 ◽  
Vol 17 (6) ◽  
pp. 917-921 ◽  
Author(s):  
Robert Marshall
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Viscoelastic Properties ◽  
Inverse Relationship ◽  
Work Of Breathing ◽  
Intrathoracic Pressure ◽  
Mechanical Work ◽  
Lung Volumes ◽  
Pressure Swing ◽  
Work Done

An electrophrenic stimulator has been used on anesthetized cats and dogs to investigate the intrathoracic pressure produced by a given stimulus at different lung volumes. With a stimulus of fixed strength the resulting intrathoracic pressure swing bears an inverse relationship to lung volume. The mechanical work done in response to a given stimulus is dependent on the viscoelastic properties of the lungs and chest wall. The muscular work resulting from a stimulus and the efficiency of the chest muscles are also dependent on the position of the diaphragm and possibly on the position of the remainder of the chest wall. Submitted on February 27, 1962

Diaphragmatic perfusion heterogeneity during exercise with inspiratory resistive breathing

1990 ◽  
Vol 68 (5) ◽  
pp. 2177-2181 ◽  
Author(s):  
M. Manohar
Keyword(s):  
Blood Flow ◽  
Exercise Capacity ◽  
Vascular Resistance ◽  
Maximal Exercise ◽  
Perfusion Pressure ◽  
Work Of Breathing ◽  
Regional Distribution ◽  
Resistive Breathing ◽  
Exercise Induced

Regional distribution of diaphragmatic blood flow (Q; 15-microns-diam radionuclide-labeled microspheres) was studied in normal (n = 7) and laryngeal hemiplegic (LH; n = 7) ponies to determine whether the added stress of inspiratory resistive breathing during maximal exercise may cause 1) redistribution of diaphragmatic Q and 2) crural diaphragmatic Q to exceed that in maximally exercising normal ponies. LH-induced augmentation of already high exertional work of breathing resulted in diminished locomotor exercise capacity so that maximal exercise in LH ponies occurred at 25 km/h compared with 32 km/h for normal ponies. The costal and crural regions received similar Q in both groups at rest. However, exercise-induced increments in perfusion were significantly greater in the costal region of the diaphragm. At 25 km/h, costal diaphragmatic perfusion was 154 and 143% of the crural diaphragmatic Q in normal and LH ponies. At 32 km/h, Q in costal diaphragm of normal ponies was 136% of that in the crural region. Costal and crural diaphragmatic Q in LH ponies exercised at 25 km/h exceeded that for normal ponies but was similar to the latter during exercise at 32 km/h. Perfusion pressure for the three conditions was also similar. It is concluded that diaphragmatic perfusion heterogeneity in exercising ponies was preserved during the added stress of inspiratory resistive breathing. It was also demonstrated that vascular resistance in the crural and costal regions of the diaphragm in maximally exercised LH ponies remained similar to that in maximally exercising normal ponies.

scholarly journals Respiratory muscle function in the newborn: a narrative review

2021 ◽  
Author(s):  
Theodore Dassios ◽  
Aggeliki Vervenioti ◽  
Gabriel Dimitriou
Keyword(s):  
Congenital Anomalies ◽  
Muscle Function ◽  
Respiratory Muscle ◽  
Work Of Breathing ◽  
Respiratory Muscles ◽  
Current Evidence ◽  
Muscle Fibres ◽  
List Type ◽  
Respiratory Muscle Function ◽  
Neurally Adjusted Ventilator Assist

Abstract Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical applications. The respiratory muscles undertake the work of breathing and consist mainly of the diaphragm, which in the newborn is prone to dysfunction due to lower muscle mass, flattened shape and decreased content of fatigue-resistant muscle fibres. Premature infants are prone to diaphragmatic dysfunction due to limited reserves and limited capacity to generate force and avoid fatigue. Methods to assess the respiratory muscles in the newborn include electromyography, maximal respiratory pressures, assessment for thoraco-abdominal asynchrony and composite indices, such as the pressure–time product and the tension time index. Recently, there has been significant interest and a growing body of research in assessing respiratory muscle function using bedside ultrasonography. Neurally adjusted ventilator assist is a novel ventilation mode, where the level of the respiratory support is determined by the diaphragmatic electrical activity. Prolonged mechanical ventilation, hypercapnia and hypoxia, congenital anomalies and systemic or respiratory infection can negatively impact respiratory muscle function in the newborn, while caffeine and synchronised or volume-targeted ventilation have a positive effect on respiratory muscle function compared to conventional, non-triggered or pressure-limited ventilation, respectively. Impact Respiratory muscle function is impaired in prematurely born neonates and infants with congenital anomalies, such as congenital diaphragmatic hernia. Respiratory muscle function is negatively affected by prolonged ventilation and infection and positively affected by caffeine and synchronised compared to non-synchronised ventilation modes. Point-of-care diaphragmatic ultrasound and neurally adjusted ventilator assist are recent diagnostic and therapeutic technological developments with significant clinical applicability.

scholarly journals Crystallization of Polymers under the Influence of an External Force Field

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2078
Author(s):  
Rajdeep Singh Payal ◽  
Jens-Uwe Sommer
Keyword(s):  
External Force ◽  
Melting Behavior ◽  
Mechanical Work ◽  
Stem Length ◽  
Heat Of Fusion ◽  
Strong Increase ◽  
Lamellar Thickness ◽  
Equilibrium System ◽  
External Force Field ◽  
Work Done

We simulated the crystallization and melting behavior of entangled polymer melts using molecular dynamics where each chain is subject to a force dipole acting on its ends. This mimics the deformation of chains in a flow field but represents a well-defined equilibrium system in the melt state. Under weak extension within the linear response of the chains, the mechanical work done on the system is about two orders of magnitude smaller as compared with the heat of fusion. As a consequence, thermodynamic and simple arguments following the secondary nucleation model predict only small changes of the crystalline phase. By contrast, an increase of the stem length up to a factor of two is observed in our simulations. On the other hand, the lamellar thickening induced by the external force is proportional to the increase of the entanglement length in the melt prior to crystallization as measured by the primitive path method. While the mechanical work done on the system is only a small perturbation for thermodynamics of polymer crystallization, the change of the primitive path is large. This suggests that a strong increase in the lamellar thickness induced, by external deformation, a topological rather than a thermodynamic origin.

Respiratory Muscle Conditioning and the Work of Breathing: A Critical Balance in the Weaning Patient

1991 ◽  
Vol 2 (3) ◽  
pp. 405-414 ◽  
Author(s):  
Maureen E. Shekleton
Keyword(s):  
Respiratory Muscle ◽  
Work Of Breathing ◽  
Critical Role ◽  
Respiratory Muscles ◽  
Clinical Intervention ◽  
Ventilatory Function ◽  
Muscle Conditioning ◽  
Ventilatory Capacity ◽  
Demand And Capacity ◽  
Research Show

Normal ventilatory function depends on a balance between ventilatory demand and ventilatory capacity. The respiratory muscles play a critical role in achieving this balance. For patients experiencing ventilatory dysfunction, interventions that improve respiratory muscle function and therefore increase ventilatory capacity may be one way of restoring the balance and promoting ventilatory function. Respiratory muscle conditioning, or training the muscles to improve their strength and endurance, may be a useful clinical intervention in the weaning patient. Results of research show that muscle training may increase the ability of some patients to resume spontaneous ventilation. Continued research is needed to identify the appropriate training protocols for patients experiencing an acute imbalance between ventilatory demand and capacity

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