11. COPD

Question 1

Chronic obstructive pulmonary disease (COPD) is characterised by an increase in expiratory airflow resistance, which results in:

Answer 1

> Increased total lung capacity (TLC)

> Increased residual volume (RV)
Increased functional residual capacity (FRC)
Reduced forced expiratory volume in 1 second (FEV1) to FVC ratio (<80%)

The most important cause of COPD is cigarette smoking and therefore patients with COPD may also suffer from associated smoking-related diseases such as ischaemic heart disease, peripheral vascular disease, cerebrovascular disease and lung cancer.

Question 2

How would you assess a patient with COPD for anaesthesia?

Answer 2

Assessment is based on taking a relevant history, detailed clinical examination and review of investigations.

History:

> Establish the degree of respiratory compromise, based on:

• Exercise tolerance – the ability to climb two flights of stairs without stopping correlates with good cardiorespiratory reserve
• Symptoms of dyspnoea – when present at rest or on minimal exertion,this indicates severe compromise
• Ability to perform activities of daily living independently
• Number of hospital admissions for exacerbations of COPD and their outcome, e.g. admission to ITU

> Establish current treatment regimen, e.g. bronchodilators, steroids, home oxygen.

> Review respiratory physician’s clinic letters.

> Obtain a smoking history.

Question 3

Examination:

Answer 3

> Ability to talk in full sentences
> Peripheral or central cyanosis
> Nicotine-stained fingernails
> Use of accessory respiratory muscles
> Evidence of right heart failure secondary to pulmonary hypertension, e.g. raised jugular venous pressure, hepatomegaly and peripheral
oedema
> Chest examination – crackles or wheeze
> Ask to observe the patient walking in the ward, if appropriate

Question 4

Investigations:

Answer 4

Target investigations to define the extent of the disease, establish pre-operative baseline respiratory function and enable respiratory optimisation.

> Bloods – FBC may reveal polycythaemia from chronic hypoxaemia.

> ECG – may show right ventricular hypertrophy.

> CXR – look for hyperexpanded lung fields or the presence of bullae.

> ABG – on air, as a baseline.

> Pulmonary function tests – spirometry (reduced FEV1: FVC ratio) and flow–volume loops.

Question 5

> Indicators of the requirement for likely post-operative ventilation include:

Answer 5

• FEV1 <1 L
• FEV1: FVC ratio <50%
• Baseline type 2 respiratory failure

Question 6

What are the anaesthetic implications for a patient with COPD presenting for surgery?

Answer 6

> Anaesthesia and surgery may result in a peri-operative decline in respiratory function.

> Certain sites of surgery are particularly high risk in terms of post-operative
respiratory morbidity in COPD patients, namely thoracic and upper
abdominal surgery.

> General anaesthesia results in a reduction in FRC

> Atelectasis reduces pulmonary compliance. This may lead to intra-operative and post-operative hypoxaemia and increases the risk of barotrauma in patients requiring ventilation.

> Post-operative hypoventilation is common in patients with COPD, especially when opiate analgesia has been administered.

> Consider the level of care required post-operatively, based on the severity of COPD and the extent of planned surgery. This may range from wardbased
care to level 3 ITU support.

Question 7

How can a patient with COPD

be optimised pre-operatively?

Answer 7

A detailed assessment of the patient is essential in order to establish the extent of the disease and so the resulting risk.

This allows the employment of targeted interventions to optimise the patient’s condition. The following
interventions should be made:

> Smoking cessation – if smoking is stopped at least 8 weeks prior to surgery, there is a demonstrated reduction in peri-operative respiratory
morbidity.

> Optimal medical treatment of COPD – a recent review by a respiratory physician is essential to ensure optimal pharmacotherapy, e.g. bronchodilators, steroids and treatment of intercurrent infection.

> Incentive spirometry – this has been proven to improve peri-operative outcomes and should be instituted pre-operatively.

> Peri-operative chest physiotherapy – to maintain lung volumes, secretion clearance and prevent atelectasis.

> Early post-operative mobilisation

Question 8

Regional or general anaesthesia?

Answer 8

This area is controversial as the evidence supporting a reduction in overall peri-operative morbidity and mortality in patients with COPD having surgery
under regional anaesthetic techniques is mixed.

However, it is clear that
excellent post-operative analgesia (via regional techniques or systemic opiates)
is essential for good peri-operative outcomes in this patient population.

Certain types of surgery lend themselves extremely well to regional techniques, e.g. orthopaedic lower limb surgery. These operations may be
performed under spinal anaesthesia, therefore avoiding the effects of general anaesthesia for the patient with COPD.

Upper abdominal and thoracic surgery also lends itself well to epidural analgesia, allowing excellent post-operative analgesia, which may reduce
peri-operative respiratory complications.