Geriatric Anaesthesia
.Dr. B. K. Prasad.
Nalanda Medical College, Patna

  
The people over 65 years of age have conventionally been regarded as elderly and population of elderly is growing fast in every country, this will have a major impact on demands of health care services and treatment specially surgery. Ageing increases the probability of a person to undergo surgery. it is reported that an elderly people requires surgery four times more often than the rest of the population and this number will increase by 25% by 2020.  Moreover, perioperative morbidity becomes more frequent in the elderly with steep increases after the age of seventy five.
Ageing is progressive physiological progress, which is characterized by –

1. Decline end organ reserve
2. Decline in functional capacity
3. Increasing imbalance of homeostatic mechanism
4. Increasing incidence of pathological process (accompanying)

Pathophysiology of ageing---
A  variety of  deleterious process continuously attack DNA, protein, lipid, (free radicles sugar, amines etc) . Age alters both pharmacokinetic and pharmacodynamics aspect of anaesthetic management. The functional capacity of organs declines and co – existing diseases further contribute to this decline.
Body composition – there is loss of skeletal muscle mass and increase in fat with reduced total body water.  There is loss of hepatic mass so 20-40% less of  flow  in liver . Atherosclerosis is inevitable. Initial blood concentration of bolus drug is higher in older patients partly due to contracted blood volume but it takes longer to achieve the greater effect- reason is still unexplained. About 6% decrease in MAC  is reported per decade of age.
Cardiovascular effects of ageing-  Decrease in  drug metabolism due to decrease in  clearance and increase in body fat. Elderly have decreased Hear rate response to catecholamine/ exercise/ impaired auto regulation of blood pressure as baroreflex control is decreased.   Stiffening of myocardium leads to slow diastolic relaxation, poor filling of ventricles , so central blood volume is low- leading to postural hypotension and the change in volume status may be poorly tolerated. .    They have  higher incidence of conduction abnormalities. They have increased reliance on Frankline-Starling mechanism for cardiac output.
Respiratory---- Stiffening of chest wall, decrease in elasticity of lung parenchyma-   progressive decline in the functional capacity  causes ventilation perfusion mismatch. Ther is 50 % decrease in ventillatory response to hypercarbia or hypoxia.  Upper airway obstruction, due to loss of muscle tone is common( 75% of elderly has sleep related airway problem after the age of 65yrs)  Less effective cough reflex leads to Pneumonia,  COPD, common  among the elderly. Geriatric populations have more incidence of postoperative  respiratory complications.
Renal---  Reduced renal  cortical mass ( 20-25%) and upto 50% at the age of 80 yrs.   Decreased renal function  causes prolonged effects of drugs and impaired electrolyte balance in elderly people. Aged kidney do not eliminate excess sodium and they do not retain sodium when  necessary.   They are more prone to renal insufficiency dehydration, electrolyte imbalance & acute renal failure postoperatively.
Nervous system------ Ageing results in a decreased nervous tissue mass (10% reduction at 80 yrs), neurotransmitters, dopamine, serotonin GABA and Acetylecholin system suffers a lot.  This effects cognitive, sensory,  motor, autonomic  functions. They are sensitive to stress , infections, dehydration,  hypotension , impaired cognitive functions due  to  neuronal damage, cerebrovascular disease and reduced blood supply to brain.
Diabetes affects 12-15% of patients in elderly population. The incidence is increasing day by day.  There is decreased Insulin secretion in response to glucose load.  Diabetic neuropathy is accompanied by increased risk of aspiration, orthostatic hypotension; urinary retention etc. dehydration is common.  The degree of diabetic stability and patient’s adherence to medical instructions should be evaluated thoroughly prior to planning for surgery and anaesthesia.
Increasing age is always related to decrease plasma protein level. The abnormal binding capacity and increase in body fat results in greater volume distribution and altered drug distribution, leading to  abnormal blood level of drugs.
The outcome of any interventional surgery will depend on-

1. Age
2. Physical status
3. Co –existing disease
4. Type and extent of surgery
5. Nature of intervention- elective/ prepared/emergency

Before planning for surgery one should decide, what benefit the patient will get after this surgery. This should be discussed and confirmed by the  responsible family members and the patient.  The procedure should be done  to improve the quality of patients life .
Preoperative evaluation,  optimization, and perioperative management ---
A careful assessment is always related to better outcome.  Co-existing disease has major influence on the outcome of surgery than the risk of anaesthesia and surgery itself.

1. Cognitive function test should be performed and score should be noted. Psychological preparation of the patient with appropriate premedication should be achieved.  .Anticholinergics may not be required as salivary gland atrophy is usual but H2 antagonists and prokinetic drugs are useful.
2. History of present illness, disease, and detailed history of associated conditions should be noted. Collateral history may be important from relatives, friends and old papers. History of medications should be noted. History about daily activity and premorbid status should be clearly defined.
3. Examination of the patient- Introduce yourself, gain the confidence, ensure comfort, warmth, and dignity to achieve proper clinical evaluation.  Examine for assessment of all the relevant system and clearly note down your findings .like Pulse BP, weight nutritional status, smoking habits, exercise tolerance etc.
4. Investigate for- ECG, CBC, Urea, Creatinine, blood sugar, electrolytes and as directed by clinical evaluation reports.
5. Intravenous cannulation for adequate and free flow of fluids should be accessed .
6. Preoperative oxygenation to raise the oxygen reserve.
7. Air way management may be difficult due to several unknown or known reasons like -osteoporotic mandibles, loose teeth, dentures, stiffness of temporo- mandibular joints, Cervical spondylosis, artghritis of atlanto-occipital joint etc.
8. There may be increased sensitivity to some or more drugs used by anaesthetists. MAC decreases (6%) for every decade. There is altered activity of neuronal ion channel, synaptic activity and receptor sensitivity. Less Opioids is required even neuromuscular blocking drugs have prolonged action. If possible consider using shorter acting drugs. Desflurane or Sevoflurane are best inhalational as they have rapid arousal and fewer critical events in early recovery periods.
9. Maintenance of normothermia or warmth is essential. shivering  increases the demand of oxygen , respiratory capacity is reduced, this may invite myocardial ischemia
10. Meticulous fluid management is necessary. Dehydration, intraoperative loss, urine output and vascular status should be kept in mind. .  Hypo or hyper volume state influences morbidity.
11. Careful positioning with appropriate padding is essential, as neuroparexia, contracture, osteoporosis and loss of muscle mass is common.

Post operative care-

1. Risk of respiratory compromise due to position, pain, fluid and oxygen demand / supply.
2. Deep vein thrombosis and pulmonary thromboembolism is common in ageing people. Calf compression devices, unfractionated heparin , low molecular weight heparin should be used as  and when required.
3. Early feed should be started  for  proper nutritional requirements.
4. Pain perception does not decrease with age.  Pain assessment, usually difficult due to dementia, aphasia or other cognitive dysfunction.  It   should be taken care properly with appropriate measures.  Multimodal combinations and use of nerve block minimizes the side effects of analgesics.  NSAID are effective but there is higher incidence of gastric bleeding in elderly. Tramadol and other Opioids are well tolerated and effective for moderate to severe pain.  Safest is paracetamol with least side effects.
5. Fluid management should be strictly taken care and urine  output should be measured.
6. Proper oxygenation should be managed with proper oxygen therapy. There will be reduced response to hypoxia and hypercarbia, even protective reflexes will be poor. Close monitoring   is the answer for all this.
7. Cognitive function and support is essential in ageing persons.
8. Early mobilisation, physiotherapy, confidence development facilitates the post operative recovery in this age group people.
9. Multidisciplinary and team approach is always recommended for elderly people.