40. Ageing

Question 1

How does ageing alter physiology,
and how does this impact on your
anaesthetic practice?

Answer 1

Ageing is an irreversible process,
which causes gradual reduction in the
reserve of each system.

The process affects everyone 
at different speeds,
and often the decline is 
not obvious until almost 
total loss of reserve occurs.

It is important to make a global assessment
addressing physical,
psychological and
relevant social issues.

Question 2

Cardiovascular system:

4

Answer 2

1
> Fewer pacemaker cells, 
making atrial fibrillation 
and other arrhythmias
increasingly common with age. 

A pre-operative ECG is essential to look
for any underlying pathology.

The tendency towards bradycardia 
(sinus or otherwise) 
is exaggerated during general anaesthesia,
 so consider the use of anticholinergic
 agents such as glycopyrrolate.

2
> The compliance of the whole vascular system reduces.

There is reduced compliance of the left ventricle,
which hypertrophies in the face of
increased afterload.

Atherosclerosis is often present and
contributes to the development of hypertension.

3
> Baroreceptor reflexes become less efficient 
with age and so compensation 
for a change in posture, 
for example is reduced, 

can lead to hypotension.

The tachycardic response
is attenuated, and the elderly

increase their cardiac outputs
by increasing stroke volume,
rather than heart rate.

To try to minimise all these effects,
aim to ensure adequate,

but not overhydration prior to induction,
 and try to avoid rapid
swings in blood pressure 
during induction and 
subsequent maintenance
of anaesthesia.

 Hence, intravenous induction of anaesthesia
 using propofol should be slow, 
titrating the dose to effect, 
remembering that the
arm–brain circulation time 
may be greatly increased.

4
> In addition to the effects of normal ageing,
there may be other pathology
such as ischaemic heart disease.

Question 3

Respiratory system:

8

Answer 3

1
> ↓ pulmonary elasticity.

2
> ↓ chest wall and lung compliance.

3
> ↓ TLC, FEV1, FVC, IRV.

4
> ↑ RV.

5
> FRC is not altered
 but closing capacity gradually 
encroaches on it, and will exceed it, 
when supine, from around 65 years old.

6
> Upper airway tone and the
 cough reflex decrease, 
causing an increased
risk of obstruction and airway soiling.

7
> The elderly are more prone to
infections and pulmonary emboli, 
and the
incidence of diseases such as COPD 
increases with age.

8
> In elective surgery it may be sensible
to refer the patient to the respiratory
physicians for pre-optimisation 
of any chest pathology.

Question 4

Renal:

Answer 4

1
> The kidney’s ability to both 
preserve and 
excrete water and 
electrolytes
decreases.

2
> A reduction in muscle bulk is
reflected in a decreased baseline creatinine.

3
> Careful attention to fluid balance,
both peri- and post-operatively,
is required.

4
> It is sensible to avoid NSAIDs in those 
with pre-existing renal failure, and
to limit their use to 3 days in 
those with normal renal function.

5
> Be aware that a modest rise in creatinine
level may reflect a significant
decline in renal function.

Question 5

Central nervous system:

Answer 5

1
> The acuity of the special senses
(sight, hearing) decreases with age.
This can lead to difficulties in communicating,
and can increase confusion in the elderly.

2
> Confusion and dementia increase with age
and can be exacerbated by anaesthesia.

3
> Cerebrovascular disease is common.

4
> Avoid intra-operative hypotension,
which may result in cerebrovascular accident

and attempt to avoid any
centrally acting drugs that increase
confusion where possible,
e.g. atropine. It is sensible to try to recover
confused patients in a quiet, calm, well-lit environment.

Question 6

Musculoskeletal:

Answer 6

1
> Skin may be fragile.
Extra care should be taken
when moving the patient

and attention to pressure areas
to avoid the development of
pressure sores.

2
> Arthritis is very common, 
and so care should be taken 
when positioning the anaesthetised 
patient so as not to cause 
pain in any affected joints.

 Pay special attention to 
neck mobility, 
especially in a patient
with rheumatoid arthritis, 
looking specifically for the 
risk of atlanto-axial
subluxation and a difficult airway.

3
> Balance, strength and postural
reflexes worsen with age and so early
mobilisation and physiotherapy
is important to try to prevent significant
loss of function in the post-operative period.

Question 7

Pharmacology:

Answer 7

Pharmacokinetics can be altered due to:
1
> ↓ body fat and ↓ body water content.

2
> ↓ renal and liver blood flow.

3
> ↓ protein affects levels of free drug available.

4
> MAC ↓ with age.

5
> ↑ sensitivity to central depressants.

6
> Polypharmacy.

7
> Be cautious with dosing drugs with narrow therapeutic indices, e.g. gentamicin.
It may be necessary to decrease the dose,
or increase the
time between consecutive doses.