General Anaesthesia

Question 1

Define Surgery

Answer 1

The treatment or investigation of injuries or disorders of the body by incision or manipulation, often involving the use of instruments, with the aim of improving function or appearance
Performed under either General/local anaesthesia
Theatre or bedside

Question 2

Types of surgery

Answer 2

Open surgery is full incisions (suffix atomy)

Minimal invasive surgery or key hole surgery (suffix oscopy)

Question 3

Define local anaesthetic

Answer 3

Used to treat or prevent pain during or after a procedure or surgery

Question 4

How does local anaesthetics work

Answer 4

Simple & quick application with fast recovery
They work by entering the cell, binding to the Na+ channel, preventing Na+ transport and thus stopping the conductance through the nerve & preventing the transmission of the pain signal to the brain
Pressure & movement still felt

Question 5

How can LA be given

Answer 5

Injections, creams, gels, sprays or ointments
Epidural & spinal - into epidural or subarachnoid space
Peripheral nerve block - will use US to locate correct nerve

Question 6

Common LA

Answer 6

amino amides such as lidocaine & bupivacaine

Question 7

What is GA

Answer 7

Purpose is to create a loss of awareness & a temporary block in gross responses to stimuli

Question 8

How does GA work

Answer 8

Skeletal muscle contraction (so patient is less likely to move)
Autonomic responses (lowers HR, BB, sweating)

Question 9

State components of GA

Answer 9

Coma
Muscular relaxation
Analgesia

Question 10

State stages of GA

Answer 10

Premedication
Induction
Maintenance
Reversal

Question 11

Explain premedication stage of GA

Answer 11

Provides ↓ anxiety
Helps with pain relief, sedation and encourages amnesia
Less common - increase day case surgery and overall pressure on NHS

Question 12

Explain induction stage of GA

Answer 12

Rapid process whereby a short-acting coma-inducing drug is given, i.e. IV propofol
+/- Sevoflurane (inhaled anaesthetic gas)
+/- intubation - may be given a paralysing drug, i.e. Atracurium to relax skeletal muscles and facilitate endotracheal intubation and mechanical ventilation.
Anaphylaxis (severe allergic reaction) can happen although rare - patients closely monitored

Question 13

Explain maintenance stage of GA

Answer 13

When surgery starts
State of coma in maintained through continuation of anaesthetic, IV analgesics & muscle relaxants + narcotic drugs (pain relief)

Question 14

Explain reversal stage of GA

Answer 14

Begins before the surgery has finished with the reduction in the anaesthetic drugs
Drug given (Neostigmine) to reverse effects of paralysis so patient can start trying to self-ventilate
Occasionally after this if patient are not spontaneously breathing after Neostigmine then another drug to reverse effect of narcotics is given, i.e. Narcan. However analgesic effect will subside so patients will need another form of pain relief

Question 15

State effects of GA on the respiratory system

Answer 15

1. G.A. has a detrimental effect on respiratory function
2. Under GA FRC may be lowered which encroaches on CV, reduces lung compliance, increases airway resistance and leads to atelectasis
3. Atelectasis occurs rapidly and dependent lung collapse occurs within 15 minutes of induction
4. Risk of absorption atelectasis - associated with high levels of O2
5. Inhalation of dry, cold gas increases mucus viscosity and affects surfactant production
6. MCC stops after 90 minutes of GA
7. Impairs CNS regulation of breathing leading to hypoventilation + supine position exacerbates atelectasis
8. Handling of viscera (during surgery) –ve neural effect on diaphragmatic function
   All complications tend to produce a restrictive pattern of deficit in surgical patients

Question 16

General effects of surgery on C/R systemq

Answer 16

Often compound on to -ve effects of GA

1. Atelectasis:
   a. Pain - causes patients to guard and take smaller breaths
   b. Prolonged recumbent position - complex long duration surgery, reduces FRC
   c. Drowsiness for several hours post-op, causing immobility further reducing FRC and TV
   d. Disruption of diaphragm - specifically upper abdominal surgery, further compounded with abdominal distension following surgery
   e. Pleural effusion - fairly minor but commonly seen; can be due to the fluid given during surgery and will further exacerbate atelectasis
   f. Atelectasis → Atelectasis of other areas more likely due to restrictive pattern and thus leads to higher WOB
2. Hypoxaemia:
   a. ↓ Hypoxic vasoconstriction because of anaesthetic gases - normal response to shunt is to constrict perfusion in areas of wasted perfusion
   b. Atelectasis
   c. Oxygen-hungry - Post-op patients high risk of hypoxaemia, especially at night as normal sleep pattern (REM cycle) is obliterated due to GA. O2 sats should be monitored for first 2-4 nights post-surgery
3. Chest Infection >48 hours post-op elevated temp = infection
   a. High risk due to effects of GA but also effects of surgery

Question 17

Post-op complications of surgery and GA

Answer 17

1. Chest – Atelectasis & infection
2. Wound infection
3. Pulmonary Oedema
4. Cardiovascular problems & MI
5. Shock incl. anaphylaxis
6. DVT/PE - dehydration and immobility
7. Acute renal failure
8. Reduced gut motility
9. Nausea and vomiting - (drugs can control)
10. Psychosis & delirium
11. Nerve damage - incisions
12. Pressure sores
13. Tooth loss or chipping
14. Myalgia (muscle aches)
15. Pain - inadequate pain relief has a direct effect on other post-op complications, i.e hypoventilation atelectasis, increases O2 consumption and risk of infection
16. Haemorrhage - at risk perioperatively and post-op
17. HTN - anxiety or not taking BP med due to NBM

Question 18

State factors of respiratory muscle dysfunction post-op

Answer 18

1. Surgical trauma stimulates central nervous system (CNS) reflexes mediated by both visceral and somatic nerves that produce reflex inhibition of the phrenic and other nerves innervating respiratory muscle
2. Mechanical disruption of respiratory muscles impairs efficiency
3. Pain produces voluntary limitation of respiratory motion. These factors all tend to reduce lung volumes and can produce hypoventilation and atelectasis.

Question 19

Aims of PT in surgical patients

Answer 19

Increase lung volumes
Clear secretions
To rehabilitate and promote independence

Question 20

Physio management to increase lung volume and clear secretions

Answer 20

Mobilise/exercise - most effective and efficient but also prevents DVTs and PE's; motivational to patient especially if functional
Positioning
Breathing exercises (ACBT, TEE’s)
Adjuncts (PEP, Incentive Spirometry, IPPB, Clearways, MHI)

Question 21

PT management to rehabilitate and improve independence

Answer 21

Mobilise/exercise
ADL
Home visits
Post-op cardiac rehab classes

Question 22

Give brief overview of pre-rehabilitation (prehab)

Answer 22

A proactive approach designed to enhance functional capacity of an individual to enable them to with stand the stresses of surgery
It is associated with lower post-operative complications and earlier restoration of functional state
Multidisciplinary approach whereby patients considered holistically including nutrition, psychological and behavioural interventions as well as exercise
Opportunity for long term lifestyle changes
Timing is vital - need to have sufficient time pre-surgery to make physiological changes but also to be able to adopt a different lifestyle prior to surgery
May just be pre-warning patient what to expect post-surgery - you will be seeing them after surgery, asking them to get out of bed, that there are breathing techniques they could start before you arrive