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The respiratory system
Published in Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella, Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella
The size of the lungs and, therefore, the lung volumes depend upon an individual’s height, weight or body surface area, age and gender. This discussion will include the typical values for a 70-kg adult male. There are four standard lung volumes (see Figure 8.4 and Table 8.1): Tidal volumeResidual volumeExpiratory reserve volumeInspiratory reserve volume
Single Best Answer Questions
Published in Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury, SBAs for the MRCS Part A, 2018
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury
You request preoperative lung function tests on a patient with longstanding emphysema. What is true of the functional residual capacity?It is the sum of the tidal volume and residual volumeIt is the sum of the inspiratory reserve volume, the expiratory reserve volume, and the tidal volumeIt can be measured directly by spirometryIt is the sum of the residual volume and the expiratory reserve volumeIt is the volume of air that remains in the lung after forced expiration
Mechanical Properties of the Lungs
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Many of the lung volumes described can be measured by observing ventilation through a simple water volumetric spirometer. The residual volume (RV) (and therefore FRC and total lung capacity) cannot be measured in this way, requiring the use of gas dilution techniques. The volumes given in the following list are average values for adults (Figure 16.5): Functional residual capacity (FRC). This is the 2500 mL of air in the lungs at the end of a normal expiration (when the subject is standing). The FRC is the volume of the lungs at which the elastic outward force of chest wall expansion is balanced by the inward recoil of the lungs; muscular tone in the diaphragm is also involved (when this is lost, FRC falls by 400 mL).Tidal volume. This is a normal resting breath, usually about 500 mL. Tidal volume is measured by spirometry as the volume difference between resting inspiratory volume to the FRC.Inspiratory reserve volume. This is the volume of air that can be inspired over and above the resting tidal volume, and it is normally about 3000 mL.Inspiratory capacity. This is the total volume (3500 mL) that can be inspired from the resting expiratory state from the FRC.Vital capacity. This is the maximal volume (4500–5000 mL) expired after a maximal inspiration.Total lung capacity. This is the total volume (6000 mL) of air in the lungs after a maximal inspiration (this cannot be measured by simple spirometry).Expiratory reserve volume. This is the additional volume (1500 mL) that can be expired at the end of a normal expiration (from the FRC).Residual volume (RV). This is the volume of air (1000–1200 mL) remaining in the lungs after a maximal expiration. RV and FRC cannot be measured by simple spirometry because the lungs cannot be emptied completely after a forced expiration. They can be measured indirectly using a dilution technique involving 10% helium. The helium dilution technique is an excellent technique for the measurement of FRC and RV in normal individuals. In patients with diseased lungs, the helium dilution technique gives a falsely low FRC value because of trapped gas in the lungs. This problem can be overcome by using the body plethysmography technique where the lung volume is determined by applying Boyle's law.
The role of peripheral muscle fatigability on exercise intolerance in COPD
Published in Expert Review of Respiratory Medicine, 2021
Mathieu Marillier, Anne-Catherine Bernard, Samuel Verges, J. Alberto Neder
Using an innovative method (an immediate switch from cadence-independent to isokinetic cycling at the peak of ramp-incremental test) to quantify exercise-induced muscle fatigue, Cannon and colleagues [68] reported greater muscle fatigability in patients with COPD as opposed to controls: the drop in maximal voluntary isokinetic locomotor power between baseline and exercise cessation as a fraction of ramp-incremental peak power was twofold that observed in controls. In fact, peripheral muscle fatigability was associated with more severe airflow obstruction (FEV1/forced vital capacity, %) and ventilatory limitation (peak-exercise minute ventilation/maximal voluntary ventilation, %) in patients with COPD [68]. Despite these findings, peak-exercise voluntary isokinetic locomotor power was ~260% of ramp-incremental peak power in COPD whereas it was ~130% in controls: the muscle power ‘reserve’ at symptom limitation was greater in the patient group [68]. It is worth noting that peak-exercise inspiratory reserve volume was 0.4 L in patients with COPD, indicative of major dynamic constraint to tidal volume expansion. The authors, therefore, concluded that patients with COPD simultaneously demonstrate excessive peripheral muscle fatigability together with large muscle power ‘reserve’ at exercise cessation, which is insufficient to set the limits of exercise tolerance.
Cardiorespiratory repercussions according to the abdominal circumference measurement of men with obstructive respiratory disorder submitted to respiratory physiotherapy
Published in Physiotherapy Theory and Practice, 2018
Bruno Martinelli, Valéria Amorim Pires Di Lorenzo, Robison José Quitério, Alexandre Ricardo Pepe Ambrozin, Eduardo Aguilar Arca, Maurício Jamami
The higher values of BMI and AC corresponded to lower values of FVC and FEV1. This may be due to increased elastic recoil of the chest wall by the imbalance of structures, mainly to higher levels of tissue in the chest wall. Moreover, diaphragmatic expansion is also mechanically affected (Steier et al., 2009). The compliance of the respiratory system is reduced due to the fact that respiration is performed at abnormally low lung volumes. Normal breathing starts at low-end expiratory volumes where the lungs are less compliant and the airways are prone to collapse during expiration (Behazin, Jones, Cohen, and Loring, 2010). However, pulmonary compression with reduced expiratory reserve volume leads to a compensatory increase in the inspiratory reserve volume (IRV) in an attempt to maintain constant vital capacity (VC) (Costa et al., 2008). The accumulation of adipose tissue along with probable chest tightness/rigidity caused by advanced age are limiting factors that compromise chest expansion (Sharma and Goodwin, 2006; Steier et al., 2009). It can be inferred that these aforementioned mechanisms were probably those which contributed to the reduction of the thoracoabdominal AI at all time periods in the CArisk group.
Respiratory muscle function and exercise limitation in patients with chronic obstructive pulmonary disease: a review
Published in Expert Review of Respiratory Medicine, 2018
Noppawan Charususin, Sauwaluk Dacha, Rik Gosselink, Marc Decramer, Andreas Von Leupoldt, Thomas Reijnders, Zafeiris Louvaris, Daniel Langer
DH brings end inspiratory lung volume during exercise close to total lung capacity and reduces inspiratory reserve volume. Consequently, patients develop a rapid and shallow breathing pattern. Impairments in dynamic respiratory muscle function might further exacerbate the rapid and shallow breathing of these patients during exercise by promoting further restriction of tidal volume (VT) expansion [38]. In addition, the relative contribution to chest wall motion of the rib cage and neck muscles in comparison to the diaphragm in COPD patients is increased [39]. With increasing lung hyperinflation in COPD patients, the inspiratory muscles of rib cage and accessory respiratory muscles are increasingly recruited even at relatively low work rates [40]. These alterations in breathing pattern and respiratory muscle recruitment should be taken into consideration when implementing therapeutic strategies aimed at improving respiratory muscle function [41].