lecture on how can anesthetist deal with Chronic obstructive lung disease during anesthesia.

1. Chronic obstructive airways disease
Clinical cases
Dr Abdullah Alsailamy

2. A 75-year-old man w ith chronic obstructive airways
d isease requires a transurethral resection of the prostate.
Out line the advantages and disadvantages of
subarachno id anaesthesia for this patient.
This question does not require a general generic discussion of the advantages and
disadvantages of spinal anaesthesia. You should focus your answer round the fact
that the patient h,,15 chronic obstructive pulmonary disease. Both the surgical condi-
tion and the medical disease arc common.
Introduct ion
Transurethral urology lends itself well to regional anaesthesia, but despite this not all
urological surgeons share the anaesthetlsts' enthusiasm and if given a choice prefer
general anaesthesia. Coexisting pulmonary disease makes the arguments in favour of
subarachnoid or extrad ural analgesia more persuasive, although there remain some
disadvantages.
• In the patient with COPD: main advantages lie in avoidance of general
anaesthesia
Full control of the airway and breathing.
No airway instrumentation with the attendant risk of provoking
bronchoconstriction.
No risk of barotrauma (pneumothorax) with IPPV.
- No respiratory depression.
No difficulty in resum ption of adequate spontaneous ventilation.
- Lower risk of postoperative chest infection .
• Advantages specific for TURP
- Earlier and easier detection of the TURP synd rome.
• Generic advantages of the technique
- Possible lower risk of venous embolism.
Good postoperative analgesia (although pain after TURP is not usually
severe).
• In the patient with COPD the disadvantages of spinal anaesthesia include:
Respiratory compromise if the block spreads to involve the intercostal
muscles.
Patients with COPD may find it difficult to lie flat.
Persistent coughing will interfere with surgery.
C":I'I1l'riC disadvantages of the technique:
I lypotension (in an elderly age group).
Unsuitable for the restless or uncooperati ve patient.
Stuno suggestion that there is increased fibrinolysis under subarachnoid
block (SAIl).
Rlsk of postdural puncture headache (small).
M rklng points: It helps if th e candidate gives some impression of having
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3. How would you assess a patient with chronic obstructive
pulmonary disease (COPO) who presents for laparotomy?
What a re the major perioperative risks and how may they
be reduced?
A patient with severe COPD can present significant anaesthetic challenges, the main
one being how to ensure that they may be kept off a ventilator and out of an inten-
sive care unit. COPD is a spectrum of disease and the question is assessing your
knowledge of the condition and your judgement in its management.
Introduction
The cardinal feature of chronic obstructive pulmonary d isease is increased airways
resistance to flow (hence the alternative title of chronic obstructive airways disease).
COPD is characterised by a disease spectrum that ranges from chronic bronchitis
which limits activity only mildly, to severe and incapacitating emphysema.
Preoperative assessment: history
• Exercise tolerance (stair climbing is a more reliable ind icator than walking on the
flat).
• Dyspnoea (on severe, moderate or minimal exertion, or at rest).
• Sputum and cough:chronic, or is there evidence of acute intercurrent infection?
• Medication: steroids, bronchodilators, domiciliary oxygen.
• Hospital and especially lTV ad missions for exacerbations.
• Smoking history.
Preoperative assessment: signs
• Body habitus: are they barrel-chested, plethoric, asthenic?
• Dyspnoea: are they able to talk in sentences at rest?
• Respiratory pattern: is there 'fish mouth' breathing. use of accessory muscles?
• Auscultation:are there wheezes , crackles, adventitious sounds?
• Right heart failu re: is there peripheral oedema, jugu lar venous distension,
hepatomegaly?
Preoperative assessment: investigations
May just confirm the clinical impression gained from history and examination, but
may help quantify the problem and assist in pred iction of outcome.
• CXR: may show emphysematous bullae, hyperinflation, patchy atelectasis,
fibrosis.
• fCG: may show right heart strain, low voltage.
• FBC: polycythaemia, leucocytosis.
• Arterial blood gases on air: evaluation of baseline preoperative status and
confirmation of CO2
retention if suspected.
• Pulmonary function tests: spirometry typically shows decreased FEV, and
decreased FEV, : FVC (forced vital capacity) ratio.A large number 01variables can
be defined. Flow- volume loops may be of more use in characterising airway
obstruction. An FEV1
: FVC ratio of <50% is associated with increased morbidity
and mortality after all forms of body cavity surgery.
• Predictors: FEV1
< 1 L. p.C02
> 7 kl'a, FEV! : rvc ratio <50'>:••111 predict
n-quin-rm-nt for postoperative ventilatory support (p.trlkul.trly .,fh·r u!'pt.·r
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4. Perioperative risks: anaest hesia and surgery
Anaesthesia
• Pulmonary function. Exerts a generally deleterious effect.
Decrease in FRC (33%), VC (up to 50%), pulmonary compliance etc. follow
all forms of general anaesthesia.
Atelectasis, hypoxaemia, hypoventilation are common.
• Barotrauma
Associated with IFPV and airways resistance.
Use of N2
0 in presence of bullae or emphysematous blebs.
• Airways reactivity
Associated with intubation, airway manipulation.
May be provoked by histamine releasing anaesthetic agents (avoid).
Surgery
• Body cavity surgery is associated with significant morbidity:
Thoracic and upper abdominal > lower abdominal.
Prolonged surgery in supine position.
Diaphragmatic excursion is impaired, restricted respiratory expansion d ue
to pain.
Risk reduction
The key to risk reduction is the optimisation of the patient's perioperativc condition:
• Smoking. Cessation is difficult in patients w ith a lifelong habit, but reduction in
postoperative respiratory morbidity will result it it can be achieved 2 months
prior to surgery.
• Pharmacology. Optimise the regimen, particularly if there is a reversible
component. Appropriate antibiotic treatment of any intercurrent chest infection.
• Physiotherapy. Pre-emptive and with use of techniqu es such as incentive
spirometry.
• Analgesia. Good postoperative analgesia (i.e. by epidural) will reduce respiratory
complications incident upon diaphragmatic splinting and basal atalectasis due to
inhibition of deep breathing by pain.
• Regional anaesthesia. Use wherever feasible, but must beware anaesthetising the
intercostal muscles with high neuraxial blocks, or using techniques which impair
phrenic nerve function (interscalene block).
• Ambulation. Encourage early mobilisation.
Marking points: Clinical experience and judgement is as important as the
respiratory numbers in deciding whether or not these patients are going to
require postoperative intensive care. You need to emphasise those clinical
features as well as outlining an anaesthetic strategy that will minimise that
risk. Good preoperative preparation and optimal postoperative analgesia are
crucial to that aim.