The Effects of Aging on the Cardiopulmonary System

1
The Effects of Aging on the Cardiopulmonary System

• Chapter 11

2
Influence of Aging on the Respiratory System

• Most of the pulmonary function indices reach
  their maximum levels between 20 and 25 years of
  age and then progressively decline.
• The precise influence of aging on the respiratory
  system is difficult to determine.

3
Static Mechanical Properties

• With aging, the elastic recoil of the lungs
  decreases, causing lung compliance to increase.
• The decrease in lung elasticity develops because
  the alveoli progressively deteriorate and enlarge
  after age 30.
• Structurally, the alveolar changes resemble the
  air sac changes associated with emphysema.

4
Static Mechanical Properties

• With aging the costal cartilage of the thoracic
  wall progressively calcify, and causes a
  structural change in which the thorax becomes
  less compliant.
• The reduction in chest wall compliance is
  slightly greater than the increase in lung
  compliance, resulting in an overall moderate
  decline in total compliance of the respiratory
  system.

5
Volume and Capacity Changes

• It is common to see a drop in TLC with aging due
  to the decreased height associated with aging.
• Residual volume tends too increase with age due
  to age-related alveolar enlargement and small
  airway closure.
• Since the RV increases, the FRC also increases
  and forces the inspiratory capacity to decrease.

6
Dynamic Maneuvers and Aging

• Dynamic maneuvers refer to flow rates during
  ventilation.
• Due to the loss of lung elasticity associated
  with aging, there is a reduced efficiency in
  forced air expulsion.

7
Diffusion Capacity and Aging

• The pulmonary diffusion capacity progressively
  decreases with age.
• It is estimated that the DLCO falls about 20
  over the course of adult life.
• This is probably the result of decreased alveolar
  surface area and decreased pulmonary capillary
  blood flow.

8
Alveolar Deadspace Ventilation

• It is estimated that the alveolar deadspace
  ventilation increases about 1 ml per year
  throughout adult life.
• It is unknown why this occurs but is may be
  associated with the structural changes involved
  in the aging process.

9
Pulmonary Gas Exchange

• The alveolar-arterial oxygen tension difference
  P(A -a)O2 progressively increases with age.
• This is due to several factors
• physiologic shunting
• V/Q mismatch
• decreased diffusion capacity

10
ABGs and Aging

• The PaO2 progressively decreases with age by
  about 1 mm Hg per year for each year after 60.
• The PaCO2 remains fairly constant throughout
  adult life due to the greater diffusion ability
  of CO2.
• Because the PaCO2 remains fairly constant, the pH
  and HCO3 also remain constant.

11
Hb and Aging

• Anemia is a common finding among the elderly.
• This is due to several factors
• red bone marrow degeneration
• gastrointestinal (GI) atrophy
• GI bleed
• malnutrition

12
Control of Ventilation

• The ventilatory response to both hypopxia and
  hypercapnia diminishes with age.
• This may be due to the reduced sensitivity of the
  central and peripheral chemoreceptors.

13
Pulmonary Diseasein the Aged

• Aging is associated with the presence of chronic
  diseases (i.e. lung CA, bronchitis, emphysema).
• The incidence of serious infectious pulmonary
  diseases is significantly greater in the elderly.
• Evidence suggests that this is due to the
  impaired defense mechanism in the aged.

14
Aging and theCardiovascular System

• A variety of adverse changes develop in the
  cardiovascular system with age.
• The major causes of death in the aging population
  are diseases of the cardiovascular system.
• The major changes are in
• heart structure
• heart work (HR and SV)
• cardiac output
• PVR and B/P

15
Exercise and its Effects on the Cardiopulmonary
System

• Indian River Community College
• Cardiopulmonary Anatomy and Physiology

16
Exercise Statistics

• During heavy exercise, components of the
  cardiopulmonary system may be stressed close to
  their limit
• Valv may increase 20 fold
• O2 diffusion may increase 3 fold
• C.O. may increase 6 fold
• O2 consumption may increase 20 fold
• When the level of exercise is greater than the
  ability of the cardiopulmonary system to provide
  a sufficient supply of O2 to the muscles,
  anaerobic metabolism ensues.

17
Ventilation

• The precise mechanism responsible for increased
  alveolar during exercise is not well understood.
• Exercise causes the body to consume a large
  amount of oxygen and, simultaneously, to produce
  a large amount of CO2.
• Figure 14-1 summarizes some possible pathways
  that the body uses to increase alveolar
  ventilation.

18
Alveolar Ventilation

• During strenuous exercise, alveolar ventilation
  can increase to 120 LPM, a 20-fold increase.
• The increased alveolar ventilation is produced
  mainly by an increased depth of ventilation
  (increased Vt) rather than an increased rate.
• During very heavy exercise, both an increased
  depth and frequency of ventilation is seen.

19
Oxygen Consumption

• At rest, normal O2 consumption is about 250
  ml/min.
• The skeletal muscles account for about 35-40 of
  the total O2 consumption.
• During exercise, the skeletal muscles may account
  for more than 95 of the O2 consumption.
• O2 consumption may increase to over 3500 ml of
  O2/min during exercise.

20
ABGs During Exercise

• No significant PaO2, PaCO2, or pH changes are
  seen between rest and approximately 60-70 of
  maximal O2 consumption.
• During heavy exercise, when lactic acid is
  present, both the pH and PaCO2 decline.
• The PaO2 remains fairly constant during mild,
  moderate, and heavy exercise.

21
Oxygen Diffusion Capacity

• The O2 diffusion capacity increases linearly in
  response to the increased O2 consumption, during
  exercise.
• The O2 diffusion capacity may increase as much as
  3-fold during maximum exercise.
• This occurs mainly due to the increased cardiac
  output that is associated with exercise.

22
Circulation

• Heavy exercise is one of the most stressful
  conditions the circulatory system encounters.
• Blood flow to the working muscles may increase as
  much as 25-fold, and the total CO may increase by
  6-fold.
• During exercise, 3 physiologic responses must
  occur 1) sympathetic discharge, 2) increased CO,
  and 3) increased arterial blood pressure.

23
Sympathetic Discharge

• At the onset of exercise, the brain transmits
  signals to the vasomotor center in the medulla to
  trigger a sympathetic discharge, thereby,
  causing
• the heart to increase its rate and strength of
  contraction
• the blood vessels of the peripheral vascular
  system to constrict, except for those supplying
  the working muscles.

24
Increased Cardiac Output

• The increased O2 demands during exercise are met
  almost entirely by an increased CO.
• The increased CO during exercise results from
• increased stroke volume
• increased heart rate

25
Increased Arterial BP

• There is an increase in arterial blood pressure
  during exercise because of
• sympathetic discharge
• increased CO
• vasoconstriction of the blood vessels in the
  non-working muscle areas
• Depending on physical conditioning, systolic
  arterial blood pressure may increase 20-80 mm Hg.

26
Pulmonary Vascular Pressures

• As O2 consumption and cardiac output increases
  during exercise, the systolic, diastolic, and
  mean pulmonary arterial and wedge pressure also
  increases.
• This mechanism enhances O2 uptake by
• distending the pulmonary capillaries
• opening closed pulmonary capillaries

27
Muscle Capillaries

• At rest, approximately only 20-25 of the muscle
  capillaries are open.
• During heavy exercise, all these capillaries open
  up to facilitate the distribution of blood.
• This reduces the distance that O2 has to travel
  from the capillaries to the muscle fiber.
• At the same time, the blood vessels of the
  viscera and non-working muscles constrict.

28
Body Temperatureand Exercise

• During exercise, the body generates a tremendous
  amount of heat and heat production may increase
  as much as 20-fold up to 103o F.
• Most of the heat produced by exercise is
  dissipated through the skin.
• This requires a substantial increase in blood
  flow to the body surface.

29
Heat Stroke

• When heat loss is impaired, either by very hot
  and humid conditions or due to inadequate
  ventilation, the individual is susceptible to
  heat stroke.
• Symptoms of heat stroke include
• profuse sweating - extreme weakness
• muscle cramping - exhaustion
• nausea - dizziness
• unconsciousness - circulatory collapse
• confusion