1Pathophysiological changes in the elderly
Section snippets
Increasing life expectancy
In recent decades life expectancy in the USA and Europe has been prolonged in men and women to approximately 74 years and 80 years, respectively. Many factors contribute to this development, but medical progress seems to be the most effective one.1 Demographical data indicate that the elderly are the most rapidly growing segment of the population in industrialized countries.
Currently, in Europe, inhabitants aged 65 and older represent 15–19% of the population. It is estimated for the year 2025
Heart
Age-related cardiovascular morbidity and mortality has been determined to be the main contributor in cases of overall adverse perioperative outcome.18
Cardiovascular reserve is strongly affected by ageing. Stress factors—such as increased flow demand by physical exercise, or post-operative demand due to acute autonomic reflex control (e.g. change of posture) or severe disease with hyperdynamic response (myocardial ischaemia, tachyarrhythmia, uncontrolled hypertension)—may induce a rapid
Changes in volumes
Ageing is characterized by a loss of elastic recoil of the lungs and impaired thoracic movement for inducing intrathoracic volume changes, resulting in a shift of the pressure–volume curve to the left.45 Static lung compliance increases with age, whereas dynamic compliance becomes more frequency dependent. Airway conductance is not altered by ageing.46
The total lung capacity is not subject to change during the course of life, but it is important to note changes of functional volumes reflected
Kidneys
The kidneys are characterized by a progressive reduction of renal mass with ageing due to glomerulosclerosis, paralleled by thickening of the vascular intima, fibrosis of the stoma and chronic infiltration by inflammatory cells. Glomerulosclerosis results in a decline in renal plasma flow (RPF) and glomerular filtration rate (GFR).51 Because GFR diminishes less than RPF, the filtration fraction increases to a state of hyperfiltration that, to some extent, represents a mechanism for adaptation
Drug therapy
Ageing of the nervous system is characterized by a general loss of neuronal substance. The most obvious sign is a reduced average brain weight in the elderly; brain weight was reported to be 1375 g at age 20 and 1200 g at age 80.76 The number of peripheral neurons also decreases, and muscles become innervated, overall, by fewer axons, possibly leading to denervation atrophy. A particular neuromuscular junction is not functionally changed with ageing. The plasma concentration of pancuronium
The locomotive system
Shrinkage of body height with ageing occurs because of the tendency of the cervical and thoracal spine towards hyperlordosis due to atrophy of the muscle groups of the back that usually erect the spine. Additionally, there is a reduction in height of the intervertebral discs due to changes in collagen content and architecture which add up to a reduction in height of about 5 to 7 cm when comparing age 20 with age 70; this occasionally increases the technical difficulties of spinal anaesthesia.92
Conclusion
Old age can be characterized as a continuation of life with decreasing capacities for adaptation.101 Changes in organ function may not be apparent in normal life, but may be revealed by narrowed margins of reserve to unusual exertion during surgery and anaesthesia. This is also true for the care-givers of anaesthesia themselves; although, in general, physicians tend to deny issues involving their own ageing, 80% of anaesthesiologists older than 50 were reported to have already planned their
References (104)
- et al.
Outcomes after abdominal aortic aneurysm repair in those > than 80 years of age. Recent Veterans Affairs experience
Annals of Vascular Surgery
(1998) - et al.
Left ventricular diastolic filling in the elderly: the cardiovascular health study
American Journal of Cardiology
(1998) - et al.
Effects of age and physiologic variables on right ventricular dynamics in normal subjects
American Journal of Cardiology
(1999) - et al.
Coronary artery bypass grafting in the elderly
American Heart Journal
(1997) - et al.
Effects of aging on the renal glomerulus
American Journal of Medicine
(1986) - et al.
Relationship of genetics, age and physical fitness to daily energy expenditure and fuel utilization
American Journal of Clinical Nutrition
(1989) - et al.
Influence of age on energy requirements
American Journal of Clinical Nutrition
(1995) - et al.
The thermic effect of feeding in older men: the importance of the sympathetic nervous system
Metabolism
(1990) - et al.
Effect of high dose fentanyl on the metabolic and endocrine response to cardiac surgery
British Journal of Anaesthesiology
(1981) Ageing and epidural dose requirements. Segmental spread and predictability of epidural analgesia in youth and extreme age
British Journal of Anaesthesia
(1969)