AGE RELATED CHANGES IN PHYSIOLOGY OF PATIENTS

1. Age related anatomical and
physiological changes in
cardiovascular and respiratory
system and anaesthetic implications.
DR.ZIKRULLAH

2. • The importance of pulmonary and cardiovascular physiology
to anesthetic practice is obvious.
• Anaesthetic success and failures are often directly related to
the skill of the practitioner in manipulating cardiovascular
and respiratory physiology.
• These systems undergoes progressive involution with age,
resulting in anatomical and functional changes that are
exerted on all levels.

3. • Changes in the cardiovascular anatomy and physiology that
occur with aging are responsible for the alterations in
function that are characteristic of aging.
• Respiratory system undergoes various structural,
physiological, and immunological changes with age.

4. Cardiovascular system:
• Major structural changes with aging ?
• Involves changes in :-
myocardium,
cardiac conduction system,
and, the endocardium.

5. Progressive degeneration of the cardiac structures with aging ?
• loss of elasticity,
• fibrotic changes in the valves of the heart,
• Infiltration with collagen and fat,
• Amyloid deposition,
• basophilic degeneration of cells.

6. • Age-associated structural characteristics that have the greatest
impact involve the contractility of the heart's left ventricular
wall.
• The pumping capacity of the heart is reduced with age due to
a variety of changes affecting the structure and function of
the heart muscle.
• An increase in heart mass with aging, is due to an increase in
the average myocyte size, whereas the number of myocardial
cells declines.

7. Physiological considerations in infants ?
• Stroke volume:- fixed by noncompliant and immature LV.
• CO:- sensitive to HR changes or HR dependent.
• Sympathetic nervous system ,baroreceptor reflexes are not
fully mature.
• Vagal parasympathetic tone dominant:-which makes
neonates and infants more prone to bradycardias.

8. Anaesthetic Implications:
• Immature heart -- more sensitive to depression by volatile
anesthetics and opioid-induced bradycardia.
• Intravascular volume depletion in neonates and infants may
be signaled by hypotension without tachycardia.
• Activation of parasympathetic nervous system, anaesthetic
overdose, or hypoxia -- trigger bradycardia -- profound
reductions in CO.

9. • Bradycardia associated with hypoxia : treat with oxygen and
ventilation initially.
• Patent ductus contracts in 1st few days of life & fibrose within
2-4 weeks.
• Closure of foramen ovale is pressure dependent & closes in
the first day of life.
• Neonatal pulmonary vasculature reacts to rise in PaO2 and
pH and fall in PaCO2 at birth.

10. Major age-related changes in the cardiovascular
system ?
• arterial stiffening;
• endothelial dysfunction, which promotes vasoconstriction;
• elevated systolic blood pressure and increased pulse pressure;
• increased left ventricular wall thickness;
• reduced early diastolic filling of the ventricles;
• impaired cardiac reserve;
• alterations in heart rate rhythm;
• prolonged cardiac action potential;

11. Age-related Changes In Vascular Function ?
Increased Wall Thickening and Arterial Stiffening
• Factors include increased collagen, reduced elastin, and
calcification
• decreased elasticity of the arterial vessels results in:-
• chronic or residual increases in vessel diameter
• vessel wall rigidity which impair the function of the vessel.

12. Endothelial Dysfunction
• reduction in endothelial
function.
• Reduction in amount of nitric
oxide (NO)produced by
endothelial cells.
Promotes vasoconstriction.

13. Blood vessels:
• Arteries lose elasticity , heart have to pump harder to
circulate blood.
• smaller arteries may thicken/stiffen :-
ability to dilate & constrict diminishes significantly.
• In veins age-related changes are minimal and do not impede
normal functioning.

14. Age-Related Structural Changes in the Blood Vessels

15. Age related anatomical changes in heart valves?
• Increase in valvular circumference reported in all four cardiac
valves,greatest changes occurring in the aortic valve .
• The age-associated increase in valvular circumference does not appear
to be associated with valvular incompetence.
• Other valvular changes with aging include thickening and
calcification of the cusps and leaflets.
• Clinical heart murmurs are detected more frequently.

16. Age-Related Physiological Changes In Cardiac Function ?
• Heart Rate and Cardiac Output.
• Left Ventricular Wall Function.
• Myocardial Contraction.

17. Heart Rate and Cardiac Output:
• Resting heart rate does not change dramatically with age.
• In the supine position at rest, heart rate in older men does not
differ from that in younger men.
• Cardiac output at rest is unaffected by age. Maximum cardiac
output and aerobic capacity are reduced with age.
• lower cardiac output reserve in older subjects and contributes
to declining aerobic capacity in advancing age.

18. Left Ventricular Wall Function:
• Increased Wall Thickening and Arterial Stiffening ; systolic
blood pressure increases with age.
• Amount of blood, chambers can hold may decrease.
• Left ventricular filling during the early phase of diastole
slows after the age of 20 years.
• By the 80 years of age, the rate is approximately 50% of its
peak value observed in early life.

19. Myocardial Contraction:
• There is a decrease in myocyte number in the aging
myocardium.
• Excitation–contraction coupling in the cardiac myocyte
changes during aging.
• Prolonged myocardial contraction.
• This makes the heart less able to pump efficiently.

20. Changes in the autonomic system with aging ?
• Decrease in response to β-receptor stimulation.
• Decrease in sympathetic nervous system activity.
Catecholamine β adrenergic receptors in the myocardium are
down regulated in the elderly resulting in a decreased
responsiveness to catecholamine's and sympathomimetic
agents.

21. Age-Related Electrical Conduction System Changes in
the Heart ?
• Decrease in number of pacemaker cells in the Sino atrial
node with age.
• There is an increase in elastic and collagenous (fibrous)tissue
in all parts of the conduction system.
• Fat accumulates around the Sino atrial node.
• Physiological changes
• Irritability of the myocardium may result in extra systoles,
along with sinus arrhythmias & sinus bradycardia.

22. Features Of The Electrocardiogram Altered By
Normal Aging ?
Based on the structural changes with age .
• The P-R and Q-T intervals show small increases with age.
• There is a leftward shift of the QRS axis with advancing age.
• The S-T segment becomes flattened, and the amplitude of the
T wave diminishes.

23. Major Effects On Blood Pressure ?
• The aorta becomes thicker, stiffer, and less flexible.
• This makes the BP higher resulting in LV hypertrophy.
• Increased large artery stiffness causes a fall in DBP,
associated with a continual rise in SBP.
• Systolic BP rises disproportionately higher than diastolic.
• Higher SBP, left untreated, may accelerate large artery
stiffness and thus perpetuate a vicious cycle

25. Anaesthetic implications :
• General anaesthesia :
• Almost all anaesthetic drugs have important actions on the
cardiovascular system.
• volatile anaesthetic agents:-
• Dose dependent myocardial depression & decrease in SBP
Halothane & enflurane :-attenuation of myocardial
contractile function.
Isoflurane & sevoflurane:- due to decrease in SVR.
• Lowers arrhythmogenic threshold to
epinephrine,(halothane>enflurane>sevoflrane>isoflurane).

26. i.v. induction agents:-
• Thiopentone
• Fall in BP & increase in HR.
• Tachycardia is due to central vagolytic effect (10-30%).
• CO & ABP is decreased due to :-
• Negative inotropic action & peripheral pooling of blood.
• Hence, caution should be used when thiopental is given to patients
with LVF/RVF, old age, or hypovolemia.

27. • Propofol
• Major CVS effect - decrease in ABP due to drop in SVR , cardiac
contractility & preload.
• Factors exacerbating hypotension include large doses, rapid injection,
& old age.
• Intravenous and inhalational agents depress cardiac and vascular
smooth muscle contractility and may impair the baroreceptor response
to hypotension.

28. Regional anaesthesia (spinal or epidural) ?
• Neuroaxial regional anaesthesia techniques are usefully employed in
this patient group however these techniques may result in significant
hypotension.
• Results in vasodilatation (reduced SVR) proportional to the height of
the block.
• Elderly patients often tolerate spinal anaesthesia well, as the non-
elastic vascular tree is not as susceptible to vasodilatation caused by
sympathetic blockade compared to younger patients.

29. Respiratory system:
• functionally, separated in two
zones;
conducting zones (nose to
bronchioles) form a path for
conduction of the inhaled
gases.
respiratory zone (alveolar duct
to alveoli) where the gas
exchange takes place.

30. • TRACHEOBRONCHIAL TREE
• Partitioned into 23
generations of dichotomous
branching, extending from
trachea to the last order of
bronchioles & alveolar sacs.
• From the trachea to the
terminal bronchioles the
airways are purely
conducting pipes.

31. • BRONCHO-PULMONARY
SEGMENT
• Defined as an area of
distribution of any bronchus.
• Each lobar bronchi divides
into segmental bronchi
(tertiary bronchi), which
supply the Broncho -
pulmonary segment of each
lobe.

32. Normal respiratory physiology ?
• Pressure gradients are
established by changes in
thoracic cavity.
• increase size in thorax = a
decrease in pressure --- air
moves in.
• Decrease size in thorax =
increase in pressure --- air
moves out.

33. • Tidal volume - It is the volume of air inspired or expired with each
breath during normal quiet breathing. (500 ml)
• Expiratory Reserve volume - additional amount of air forcibly expired
after normal tidal expiration (1000 - 1200 ml).
• Inspiratory Reserve volume –It is maximal volume of air which can be
inspired after a normal (tidal) inspiration.(1900-3300 ml).
• Residual volume - amount of air remaining in the lungs even after
forced expiration (about 1.2 liters).

34. Anatomical considerations in infants ?
• Large occiput.
• Large sized tongue.
• Larynx : more cephalic, funnel
shaped & anterior.
• Epiglottis : short, stubby, omega
shaped, angled over laryngeal inlet.
• Vocal cords angled.
• Cricoid cartilage : Narrowest
portion.

35. Anaesthetic implications ?
• No doughnut is required
• Straight blades preferred
• Uncuffed tubes preferred for children
‹6 yrs.
• Tube that easily passes the vocal cords
may be tight in the subglottic region.
• Micro cuff tube:-
• Safe ,very soft material.

36. Physiological consideration in infants ?
• Increased respiratory rate
• Reduced lung compliance
• Increased chest wall compliance
• Increased metabolic rate
• Reduced functional residual capacity
• Alveoli thick walled at birth
• Dead space ventilation similar to adults
• Oxygen consumption 2-3 times higher
• Work of breathing 3 times that in adults

37. • Weaker intercostal muscles , diaphragm.
• Horizontal , pliable ribs,
• Protuberant abdomen,
• Early fatigue and Desaturation.

38. Anaesthetic considerations:
• Limited respiratory reserve.
• Horizontal ribs limits increase in VT
• Ventilation primarily diaphragmatic.
• Bulky abdominal organs :-reducing adequate ventilation.

39. • Decrease in FRC :limits oxygen reserves during periods of apnoea ,
predisposes to atelectasis and hypoxemia.
• Minute ventilation is rate dependent as there is little means to increase
tidal volume.
• Closing volume larger than FRC until 6-8 years.
• Causes an increased tendency for airway closure at end expiration.

40. Age related respiratory physiological changes ?
• Altered lung volumes.
• Altered resistance of peripheral airways.
• Decrease in elastic recoil of lungs.
• Changes in ventilation perfusion matching.
• Decreased compliance of chest walls and lungs.
• Ventilatory responses to hypercapnia , hypoxia and exercise decrease
in the elderly.
• The elasticity of the lung decreases with age.

41. Lung volume changes with age ?
• Residual Volume (RV) increases and Functional Residual Capacity
(FRC) remains unchanged.
• Total lung capacity (TLC),
• Forced Vital Capacity (FVC), all reduced as people age.
• Forced Expiratory Volume(FEV1),
• Vital Capacity.
• The annual decline in FEV1 is small at first but accelerates with age .

42. • The FEV1 decreases with age by about
27 mL/year in men but by only 22
mL/year in women .
• Forced vital capacity (FVC) decreases
as well, by about 14 to 30 mL/year in
men and 15 to 24 mL/year in women.
• The decreases in FEV1 and FVC that
occur until age 40 are thought to result
from changes in body weight and
strength rather than from loss of tissue.

43. Changes in Pulmonary Compliance ?
Lung and chest wall compliance decrease with advancing age.
Dead space increases with age because the larger airways increase in
diameter.
Elastic elements of the lung parenchyma are lost with age
Ageing is associated with a reduction in the number of small airways
and flattening of the internal surface of the alveoli.
The reduced diffusion capacity due to aging is induced from a decrease
in the lung area owing to damage to the alveoli, an increase in thickness
of the alveolar walls, and small-airways obstruction.

44. Respiratory physiology in elderly ?
• Decreased pulmonary elasticity
• Decreased alveolar surface area
• Increased residual volume
• Increased closing capacity
• Ventilation/perfusion mismatching
• Decreased arterial oxygen tension
• Increased chest wall rigidity
• Decreased muscle strength : Decreased cough
• Decreased maximal breathing capacity
• Blunted response to hypercapnia and hypoxia.

45. Age-related changes in the lung ?
• degeneration of elastin :- dilatation of alveolar ducts,
• reduction in number of small airways
• increased collagen cross-linking:- stiffer parenchyma,
• less distensible vessel walls.
• reduction in mucociliary function
• Calcification of ribs and sternum results in stiffening.
• Changes in respiratory muscles.
• Distal bronchioles have reduced diameter and tend to collapse.

46. • Lung tissues become less elastic and expansible.
• Decrease in compliance of the chest watt, due to calcification
of its articulations, dorsal kyphosis and "barrel chest".
• Decrease in the strength of respiratory muscles
• The increased static lung compliance combined with the
decreased chest watt compliance leads to an increase in the
functional residual capacity with aging.

47. Anaesthetic implications in elderly
more sensitive to anesthetic agents and generally require smaller doses
for the same clinical effect, and drug action is usually prolonged.
Airway obstruction:-
Patients are often edentulous making bag-mask ventilation difficult.
loss of airway patency due to the relaxation of the pharyngeal muscles
and posterior displacement of the tongue.

48. The supine position reduces the FRC by 0.8–1.0 L, and induction of
general anaesthesia further reduces the FRC by 0.4–0.5 L.(approx 15-
20%)
Spontaneous ventilation is frequently reduced during anesthesia.
Minimum alveolar anesthetic concentration (MAC), decreases
approximately 6% for every decade.
increasing V/Q mismatch with age.

49. Effect of anaesthetic agents ?
• All inhalational anesthetic agents depress respiratory function.
• Halothane causes rapid &shallow breathing.
• All (except ketamine, ether and nitrous oxide) cause a dose- dependent
reduction in ventilatory minute volume.
• This can be due :-
• ↓ in the respiratory rate (e.g. opioids)
• ↓in the tidal volume (e.g. volatile anaesthetics) or both (e.g. propofol).

50. Factors that influence respiratory function during
anesthesia?
• Spontaneous breathing,
• Increased Oxygen fraction,
• Body position (supine or lateral),
• Age,
• Obesity,
• Pre-existing lung diseases,
• Atelectasis & airway collapse,
• V/Q mismatch.

51. Preoperative evaluation:
• Common diseases in the elderly have a significant impact on
anesthesia and require special care.
• The risk from anesthesia is more related with the presence of co-
existing disease than with the age of the patient.
• Thus, it is more important to determine the patient’s status and
estimate the physiologic reserve in the preanesthetic evaluation.

52. Intraoperative care and anesthetic management:
• Advanced age and general anesthesia are associated with hypothermia.
• Maintenance of normothermia is important as hypothermia is related
to myocardial ischemia, and hypoxemia in the early postoperative
period.

53. • In case of general anesthesia it is of major importance to titrate drug
doses and it would be prudent to use short acting drugs.
• The duration of drug action may be prolonged if their metabolism
depends on renal or hepatic excretion.
• The elderly require less doses of opioids for pain relief.

54. Thanks !