The Structured Oral Examination in Clinical ANAESTHESIA

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Structured oral
examination 1
1
Long case 1
History
A 70-year-old male patient underwent elective abdominal aortic aneurysm
repair 24 hours ago. His past medical history includes hypertension and
ischaemic heart disease. His medications up to the day of surgery
included simvastatin 30mg o.d., enalapril 10mg o.d., atenolol 50mg o.d.
and aspirin 75mg o.d. He smoked 20-30 cigarettes until 6 months ago,
after which he completely stopped.
The intra-operative blood loss was 1.2 litres with an aortic cross-clamp
time of 65 minutes. The average urine output during the intra-operative
period was 90ml/hour. Following the release of the aortic clamp, he
required inotropic support for a brief period. He was transferred to the
intensive care unit and ventilated overnight. Postoperative pain relief is still
provided with epidural infusion of 0.125% bupivacaine and fentanyl
2mg/ml. He was weaned off the ventilator and extubated 4 hours ago.
You have been called to see the patient as he has developed shortness of
breath.
Clinical examination
He is conscious, breathless, sweaty and clammy. His peripheral oxygen
saturation is 94% whilst breathing spontaneously 60% oxygen. On
examining the chest there is bilateral equal air entry with crackles at both
bases.
Clinical Anaesthesia
Information for the candidate
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The Structured Oral Examination in Clinical Anaesthesia Practice examination papers
Table 1.1 Clinical examination.
Weight
Height
Heart rate
Blood pressure
Temperature
78kg
170cm
120 bpm
95/65mmHg
36.9°C
Investigations
Table 1.2 Biochemistry.
Sodium
Potassium
Urea
Creatinine
Blood glucose
138mmol/L
3.2mmol/L
14.5mmol/L
123mmol/L
8.5mmol/L
Normal values
135-145mmol/L
3.5-5.0mmol/L
2.2-8.3mmol/L
44-80mmol/L
3.0-6.0mmol/L
Table 1.3 Haematology.
Hb
Haematocrit
RBC
WBC
Platelets
INR
PT
APTT ratio
11.3g/dL
0.24
2.75 x 1012/L
7.5 x 109/L
296 x 109/L
1.4
14.4 seconds
1.4
Normal values
11-16g/dL
0.4-0.5 males, 0.37-0.47 females
3.8-4.8 x 1012/L
4-11 x 109/L
150-450 x 109/L
0.9-1.2
11-15 seconds
0.8-1.2
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Structured Oral Examination 1
Figure 1.1 Chest X-ray.
Figure 1.2 ECG.
aVR
V1
V4
aVL
V2
V5
aVF
V3
V6
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The Structured Oral Examination in Clinical Anaesthesia Practice examination papers
Examiner’s questions
Please summarise the case
A 70-year-old male patient, known to have hypertension and ischaemic
heart disease, recovering in intensive care following AAA repair, has
developed hypotension and hypoxia at 24 hours postoperatively following
tracheal extubation. His biochemistry results suggest impaired renal
function and hypokalaemia.
What is the differential diagnosis?
The important causes of postoperative hypotension and hypoxia in this
patient can be listed systematically as follows.
Cardiovascular system
w Myocardial infarction.
w Left ventricular failure or congestive cardiac failure.
w Arrhythmias such as atrial fibrillation (AF).
Respiratory system
w
w
w
w
Pulmonary embolism.
Pleural effusion.
Pneumothorax.
Transfusion-related acute lung injury (TRALI).
Metabolic causes
w Electrolyte imbalance.
Infection
w Severe systemic infection (sepsis).
Analgesia-related
w High level of epidural blockade.
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Structured Oral Examination 1
What are the abnormal findings in the ECG?
The ECG shows atrial fibrillation as the rhythm is irregularly irregular with
absent P waves and the heart rate is approximately 120 bpm. There is left
ventricular hypertrophy and left axis deviation suggesting longstanding
hypertension.
What are the causes of atrial fibrillation (AF)?
Cardiac causes
w
w
w
w
Ischaemic heart disease.
Mitral valve disease.
Hypertension.
Cardiomyopathy.
w
w
w
w
w
w
Hypoxia.
Acute hypovolaemia.
Sepsis.
Electrolyte disturbances - potassium, magnesium and phosphate.
Pulmonary thromboembolism.
Thyrotoxicosis.
Non-cardiac causes
In this patient the cause of AF is likely to be ischaemic heart disease,
pneumonia and an electrolyte imbalance (low potassium).
How would you treat fast atrial fibrillation?
w Ensure adequate airway and breathing, and administer 100% oxygen.
w Establish continuous ECG, blood pressure and pulse oximetry
monitoring.
w Correct any precipitating factors where possible.
w Determine if the patient is stable or not.
If the patient is unstable, he should be treated with synchronised DC
cardioversion with shocks up to three attempts. If there is no response,
intravenous amiodarone 300mg should be administered over 10-20
minutes and the shock repeated if needed, followed by an amiodarone
900mg IV infusion over 24 hours.
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