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age-associated changes in pulmonary function

Pulmonary function declines with age Physiology: 1) decreased elasticity of lung parenchyma a) changes 1] decrease in number of elastin fibers in small airways [5] 2] decrease in collagen, but increase in collagen crosslinks* 3] decrease in elastic recoil of lung b) consequences 1] increased work of breathing 2] enlarged alveolar ducts 3] enlarged alveoli [5], but decreased alveolar surface area 4] maximum inspiratory & expiratory pressures decrease 5] decrease in exercise tolerance 2) decreased activity of cilia 3) decreased vital capacity a) FEV1 decreases 30 mL/year b) FVC decreases similarly c) no change in total lung capacity [5] 4) increased residual volume (dead space) - functional residual capacity increases slightly with age [11] - increased end-expiratory lung volume in elderly with exercise [5] 5) decreased DLCO 0.5%/year 6) decreased maximum oxygen uptake (VO2 max) 7) decreased cough reflex, cough less effective in clearing secretions [5] 8) increased airway reactivity 9) diminished pO2 a) secondary to V/Q mismatch - increased A-a gradient [5] b) worse in supine than sitting position c) estimate by eq: 100 - age/3 (90 yrs = 70 mm Hg) 10) decreased response to hypoxia & hypercarbia 11) increased pulmonary artery pressure 12) muscles of respiration: decreased strength & endurance - weaking of intercostal muscles results in greater dependence on diaphragm muscle - along with loss of muscle oxidative capacity & reduced cardiac output, manifests as decreased exercise tolerance [5] 13) trachea & central airways increase in diameter 14) decreased lung mass 15) expansion of thorax 16) costal cartilage calficies, chest wall stiffens, chest compliance decreases [5] 17) persons 60-80 years emit a larger number & volume of lung aerosol particles at rest & during exercise than persons 20-40 years of age [10] - may have implications for transmissibility of lower respiratory tract infections among elderly [10] * GRS11 [5] notes a loss of elastin fibers & an increase in cross-linking (unspecified), then goes on to mention a remodeling of the lung elastin-collagen network contributing to chest wall stiffness & decreases in peak expiratory flow in the elderly * GRS11 [5] seems to infer that loss of elastin fiber cross-links is not associated with age-associated decline in exercise tolerance Pharmacology: - diminished responsiveness of asthmatics to glucocorticoids [6]

Related

asthma in the elderly lung lung disease pulmonary pulmonary function test (PFT)

General

age-related physiological changes

References

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  6. Dunn RM et al Impact of Age and Gender on Response to Asthma Therapy. Am J Respir Crit Care Med. First published online 11 Jun 2015 PMID: 26068329 http://www.atsjournals.org/doi/abs/10.1164/rccm.201503-0426OC
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  10. Schumm B et al. Lung aerosol particle emission increases with age at rest and during exercise. Proc Natl Acad Sci U S A 2023 May 22; 120:e2301145120 https://www.pnas.org/doi/10.1073/pnas.2301145120
  11. Hopkins E, Sharma S Physiology, Functional Residual Capacity StatPearls [Internet]. Dec 26, 2022 NLM, NCBI Bookshelf https://www.ncbi.nlm.nih.gov/books/NBK500007