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Ageing
Published in Henry J. Woodford, Essential Geriatrics, 2022
In older adults, there is a reduction in lung elastic recoil (making them stretchier) but also a reduction in chest wall compliance (making expansion less easy). Associated with frailty, muscles of respiration (including the diaphragm) become less strong. The combined effect of these changes is that total lung capacity (TLC) remains constant, but the reduced elastic recoil results in an increase in residual volume (RV). Vital capacity (VC) can be calculated by subtracting RV from TLC. Therefore, VC becomes reduced (seeFigure 1.4). Forced expiratory volume in one second (FEV1) is lower in older adults. As is diffusing capacity. Loss of terminal bronchioles contributes to age-related decline in pulmonary function.58 Partial pressure of oxygen (pO2) is reduced but that of carbon dioxide (pCO2) is unchanged. Respiratory drive in response to hypoxia or hypercapnia is impaired.
Respiratory system
Published in Jagdish M. Gupta, John Beveridge, MCQs in Paediatrics, 2020
Jagdish M. Gupta, John Beveridge
7.4. Pulmonary function tests in a child with moderately severe asthma are likely to showincreased vital capacity.increased functional residual capacity.normal timed vital capacity (FEV1).increased lung elastic recoil.increased total lung capacity.
Unusual Inherited Pulmonary Diseases Which Provide Clues to Pulmonary Physiology and Function
Published in Stephen D. Litwin, Genetic Determinants of Pulmonary Disease, 2020
Thomas Κ. C. King, Robert A. Norum
Idiopathic pulmonary fibrosis is the classic example of the syndrome of alveolar-capillary block [64,65-71]. The characteristic abnormality is a restrictive defect with decreases in the total lung capacity, vital capacity, functional residual capacity, but a normal residual volume. Ventilatory ability is usually preserved with near-normal maximum voluntary ventilation, and conventional indices of airway obstruction using FEV1% and Plethysmographie airway resistance almost always give normal values [72]. However, use of newer tests, such as frequency dependency of dynamic compliance and flow volume curves, show that a significant number of patients have evidence of small airway disease [30,73]. There is increase in the elastic recoil with a shift of the volume-pressure curve downwards and to the right [69]. This decrease in compliance means not only an increase in the work of breathing, but also larger changes in lung volume will require inordinate expenditures of energy. Thus, for a given level of ventilation, less work is involved with a higher breathing frequency and a smaller tidal volume.
Mechanical adjuncts for cardiocerebral resuscitation
Published in Expert Review of Medical Devices, 2019
Matthias L. Riess, Claudius Balzer
As stated above, the use of the ITD requires high-quality CPR which could be provided by the use of ACC devices [8,54]. When used during manual CPR [11,14,28], negative intrathoracic pressure by ITD is only generated by the intrinsic elastic recoil of the chest and largely depends on the quality of CPR. A rigid, non-compliant chest or fractured ribs, for example, can significantly reduce the elastic recoil. In addition, limited recoil through leaning has detrimental effects on venous return and intracranial pressure [43,55]. By using the piston device LUCAS®3 with a suction cup, the recoil is supported with a lifting force of around −3 lbs [56]. Compared to a manual ACD device such as the ‘ResQPUMP’ with a lifting force around −20 lbs, the active decompression is lower and does not exceed the neutral level, but depth and frequency are maintained without provider fatigue. Furthermore, its use can be continued during transport in an ambulance or helicopter [57], and reversible causes for cardiac arrest could be treated by interventions in the cardiac catheterization laboratory (CCL) [58].
Emphysema: looking beyond alpha-1 antitrypsin deficiency
Published in Expert Review of Respiratory Medicine, 2019
Rob Janssen, Ianthe Piscaer, Frits M. E. Franssen, Emiel F. M. Wouters
Although decreased FEV1 contributes to reduced exercise capacity in emphysema, non-obstructive emphysematous subjects also have reduced 6-min walking distance in comparison to those with neither COPD nor emphysema [13]. This highlights that factors other than airflow obstruction contribute to exercise limitation in emphysema, of which hyperinflation is regarded as an important one. Elastic recoil is the term used to describe the natural propensity of lungs to rebound after inflation. Destruction of elastic tissue in emphysema is the main pathological mechanism behind decreased recoil pressure [16,17], leading to reduced resilient properties of the lungs. Consequently, there is less inwardly directed pressure to counteract the outward pressure of the chest wall, i.e. air trapping, resulting in higher lung volumes after expiration. Severity of hyperinflation is related to dyspnea sensation by unfavorably affecting respiratory muscle mechanics [18] and cardiac function [19]. Over-inflation associates with elevated intrathoracic pressure resulting in decreased venous return to the heart. Hyperinflation becomes particularly problematic during exertion. Dynamic hyperinflation develops when breathing frequency increases and time is too short to exhale the whole volume of inhaled air [18].
Lung volume reduction with endobronchial valves in patients with emphysema
Published in Expert Review of Medical Devices, 2018
Marieke C. Van Der Molen, Karin Klooster, Jorine E. Hartman, Dirk-Jan Slebos
Several bronchoscopic techniques were developed to induce volume reduction in patients with hyperinflation. Treatments can be divided into ‘blocking’ and ‘non-blocking’ techniques. In treatment with non-blocking techniques, patients with hyperinflation qualify for intervention regardless of the presence of collateral ventilation. Non-blocking techniques focus on restoring elastic recoil or improving compliance in the emphysematous lung. This can be accomplished by the insertion of endobronchial coils (Figure 6(c)) [58], by inducing fibrosis via thermal vapor ablation [59], or the appliance of lung sealant [60]. Another non-blocking alternative is to create an airway bypass, whereby collateral ventilation is used to deflate the hyperinflated lung lobe into the adjacent lobe. However, because of loss of patency of the bypass over months, these effects are temporary and further research is needed to optimize this approach [61].