BOF: 3.19
A 75-year-old male has been admitted to the emergency
admitting unit. He has ischaemic heart disease with previous myocardial
infarction and has been on treatment for chronic heart failure. He is on
furosemide, ramipril, spironolactone and carvedilol.
He recently developed pain, redness and swelling of his
right metatarsophalangeal joint which came on acutely overnight. His GP
initially treated him with diclofenac but when he did not respond he started
him on colchicine.
Following this he developed diarrhoea, which made him
feel unwell. He stopped eating and drinking and took to his bed. The GP
referred him to the hospital, as he was worried about the deterioration in his
condition.
On examination he looked unwell, his mucus membranes were
dry, skin turgor was diminished and he was tachycardic and had low blood
pressure with a significant postural drop. There was a pan systolic murmur at
the apex, which radiated to the axilla but apart from this no other
abnormalities were detected.
Your house officer has arranged blood tests, the results
are not available as yet but he calls you to see the patient’s ECG as he
thinks it is abnormal.
The ECG shows bradycardia, flattened p waves and a broad
QRS complex.
Your next step would be:
a)
Urgent blood gas analysis
b)
10 % Calcium chloride 10 ml over 5 minutes
c)
50 % dextrose 50 ml with 10 units soluble insulin over 5 minutes
d)
Nebulised salbutamol 20 mg
e)
1.26 % Sodium bicarbonate 500ml over 30-60 mins
Answer: b)
The patient is an elderly man with ischaemic heart
disease and heart failure. He is probably a vasculopath. He is on multiple
potentially nephrotoxic drugs. He has gout (sudden onset pain redness and
swelling of his metatarsophalangeal joint) and this together with his vascular
disease increases his risk of renal disease. In addition he has been given a
NSAID, which would further increase the chances of damaging his kidneys.
Following administration of colchicine he has developed diarrhoea and
clinically there are features of salt and water depletion (“dehydration”).
This raises the possibility of pre-renal renal failure.
The possibility of developing renal failure has been
brought up by a number of features of this case. Following this the ECG
features are mentioned. These features suggest the patient has hyperkalaemia.
When hyperkalaemia results in ECG changes it is
imperative that quick action is taken.
Treatment of hyperkalaemia, which is a life threatening
condition, may be divided into 3 stages:
ü
Reduce the risk of an arrhythmia
This may be achieved by the use of intravenous
calcium chloride or calcium gluconate. Calcium chloride contains more calcium
(Calcium chloride 6.8 mmol in 10ml, calcium gluconate 2.2 mmol in 10 ml) and
hence is the preferred agent.
ü
Drive potassium into cells
This may be achieved by the
use of insulin and dextrose or nebulised salbutamol
ü
Remove potassium from the body
This may be achieved by the use of calcium
exchange resins such as calcium resonium or by the use of dialysis
Revision Tip
Revise acute renal failure
KEYS to SUCCESS in Medicine page 309-312
