9. Failure To Breath

Question 1

Intro

Approach

Answer 1

Failure to breathe adequately following general anaesthesia requires a systematic approach to its management; the cause must be elucidated and in the interim patient’s airway, oxygenation and ventilation maintained.

To establish the cause, approach the problem systematically, remembering all of the requirements for breathing, starting with the central nervous system and ending at the respiratory muscles.

Question 2

What are the causes of failure

to breath post-operatively?

Answer 2

1. > Upper airway obstruction:
2. > Decreased ventilatory drive:
3. > Inadequate respiratory muscle function:

Question 3

> Upper airway obstruction:

Answer 3

• Foreign body
• Secretions
• Oedema
• Laryngospasm

• Soft tissue collapse,
e.g. obtunded patient or
obstructive sleep apnoea

• Vocal cord palsy

Question 4

2. > Decreased ventilatory drive:

Answer 4

• Opiate-induced respiratory depression
• Presence of inhalational agents
• Extremes of arterial CO2 tension
• Loss of hypoxic drive in COPD patients
• Acute intracranial catastrophe

Question 5

3. > Inadequate respiratory muscle function:

Answer 5

• Incomplete reversal of
neuromuscular blocking agents

• Plasma cholinesterase deficiency
• High spinal anaesthesia
• Spinal cord lesion
• Neuromuscular disease, e.g. myasthenia gravis
• Restriction due to pain

• Upper airway obstruction,
e.g. foreign body, secretions, oedema,
laryngospasm or vocal cord palsy

Question 6

> Inadequate reversal after non-depolarising neuromuscular

blockers has been administered:

Answer 6

• Signs may include uncoordinated ‘see-saw’
breathing movements or
inability to sustain a head lift for >5 seconds.

Confirm the diagnosis
by checking the patient’s train-of-four with a nerve stimulator looking for fade, which would indicate a residual block. Also confirm that the
correct dose of reversal has been administered.

• Drugs administered such as magnesium sulphate can increase the duration of neuromuscular blockade.
• Ensure that the patient is not aware during the period of inadequate reversal.

Question 7

> Deranged physiology

Answer 7

Acidosis and hypothermia may also result
in failure of adequate ventilation.

Correct these where possible,

and if it is not possible acutely,
the patient may require a period of post-operative
ventilation during which deranged physiology can be corrected.

Question 8

> Poor general condition:

Answer 8

> Poor general condition:

Malnourished patients and those with
pre-existing conditions causing weakness may not have the muscle strength to sustain adequate ventilation post-operatively and again they
may require a period of extended ventilation to allow recovery.