Effect of aging on respiratory system physiology and immunology

Figures & data

Table 1 Aging and respiratory muscle strength

Study	Technique	Pdi (cm of H20)		Reduction	p-value
		Young	Elderly
Tolep et al 1995	Mueller	171±8	128±9	25%	<0.003
Polkey et al 1997	Sniff	136±17	119±22	13%	0.05

Abbreviations: Pdi, transdiaphragmatic pressure.

Figure 1 Effect of environmental exposure on airways.

Figure 2 Relationship between lung volumes and lung capacities.

Abbreviations: ERV, expiratory reserve volume; FRC, functional residual capacity; IC, inspiratory capacity; IRV, inspiratory reserve volume; RV, residual volume; TLC, total lung capacity; TV, total volume; VC, vital capacity.

Table 2 Static lung volumes

Tidal volume (TV)	Volume of air inspired or expired during quiet breathing
Inspiratory reserve volume (IRV)	Maximum volume of air inspired above the tidal volume
Expiratory reserve volume (ERV)	Maximum volume of air expired below the tidal volume
Residual volume (RV)	Amount of air in the lungs after maximum expiration

Figure 3 Age-related decline in forced expiratory volume in one second (FEV1)% predicted plotted as % of maximal at age 20 years against age.

Note: Adapted from Ware JH, Dockery DW, Louis TA, et al. 1990. Longitudinal and cross-sectional estimates of pulmonary function decline in never-smoking adults. Am J Epidemiol, 132:685-700. Copyright © 2004. Reprinted with permission from Oxford University Press.

Table 3 Lung capacities are sum of two or more static lung volumes

Inspiratory capacity (IC)	TV + IRV
Functional residual capacity (FRC)	RV + ERV
Vital capacity (VC)	TV + IRV + ERV
Total lung capacity (TLC)	TV + IRV + ERV + RV

Abbreviations: ERV, expiratory reserve volume; IRV, inspiratory reserve volume; RV, residual volume; TV, tidal volume.

Table 4 Lung function studies

Study	Time	Cross-sectional (C)/Longitudinal (L)	Age range	N	Age ≥65 years	Decline
Morris et al	1969–70	C	20–84	988	79	Linear
Crapo et al	1979–80	C	18–91	251	68	Linear
Knudson et al	1972–75	C	6–88	421	-	Linear
Dockery et al	1974–76	C	25–74	2454	430	Nonlinear
Burrows et al	1972–84	L	20–72	466	-	Nonlinear
Ware et al	1974–83	L	25–74	2454	430	Nonlinear
Enright et al	1989–90	C	65–85	777	777	Linear

Note: Adapted from Kerstjens HAM, Rijcken B, Schouten JP, et al. 1997. Decline of FEV by age and smoking status: facts, figures, and fallacies. Thorax, 52:820-7. Copyright © 1997. Reproduced with permission from BMJ.

Figure 4 Mechanism of action of beta agonist.

Abbreviations: ATP, adenosine triphosphate; cAMP, cyclic adenosine monophosphate.

Table 5 Ventilatory response to hypoxia and hypercapnia

	Young (22–30 years)	Elderly (64–79 years)	p-value
	VE (Minute ventilation) in litres/min
Kronenberg et al 1973
PaO2 40 mm Hga	40.1±4.7	10.2±1.2	<0.001
PaCO2 (L/min/mm Hg)b	3.4±0.5	2.0±0.02	<0.025
Peterson et al 1981
SpO2 75%c	30.3±2.9 L/min	20.9±2.3 L/min	<0.01
PaCO2 60 mm Hgd	48.7±4.3 L/min	34.6±2.9 L/min

Note: ^aChange in minute ventilation from baseline to during hypoxia (arterial oxygen tension of 40 mm of Hg);

^bChange in minute ventilation per unit change in arterial carbondioxide tension from baseline;

^cminute ventilation at arterial oxygen saturation of 75%;

^dminute ventilation at arterial carbondioxide tension of 60 mm Hg.

Table 6 Anatomical and physiological changes of respiratory system with aging

Anatomical
Air space size	Increased
Compliance
Chest wall compliance	Decreased
Lung compliance	Increased to unchanged
Total respiratory system compliance	Decreased
Muscle strength
Maximal inspiratory pressure (MIP)	Decreased
Trans diaphragmatic pressure (Pdi)	Decreased
Maximum voluntary ventilation (MVV)	Decreased
Lung function
FEV1	Decreased
FVC	Decreased
TLC	Unchanged
Vital capacity	Decreased
Functional residual capacity	Increased
Residual Volume	Increased
DLCO/VA	Decreased
Exercise capacity
VO2 max	Decreased
Dead space ventilation	Increased
Immunology
Bronchial fluid
Neutrophils %	Increased
Ratio of CD4^+/CD8^+ cells	Increased
Epithelial lining fluid antioxidants	Decreased

Abbreviations: DLCO, diffusing capacity of carbon monoxide; FEV1, forced expiratory volume in one second; FVC, forced vital capacity; TLC, total lung capacity; VO₂, oxygen consumption; V_A, alveolar volume.

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