ANSWER 44
This patient has acute renal failure as a result of rhabdomyolysis. Severe muscle damage
causes a massively elevated serum creatine kinase level, and a rise in serum potassium and
phosphate levels. In this case, she has lain unconscious on her left arm for many hours due
to an overdose of alcohol and intravenous heroin. As a result, she has developed severe
ischaemic muscle damage causing release of myoglobin which is toxic to the kidneys.
Other causes of rhabdomyolysis include crush injuries, severe hypokalaemia, excessive exer-
cise, myopathies, drugs (e.g. ciclosporin and statins) and certain viral infections. The urine
is dark because of the presence of myoglobin which causes a false-positive dipstick test for
blood. Acute renal failure due to rhabdomyolysis causes profound hypocalcaemia in the
oliguric phase due to calcium sequestration in muscle, and reduced 1,25-dihydroxycalciferol
levels, often with rebound hypercalcaemia in the recovery phase. This woman’s conscious
level is still depressed as a result of opiate and alcohol toxicity and she has clinical and radi-
ological evidence of an aspiration pneumonia. She has a mixed metabolic and respiratory
acidosis (low pH, bicarbonate) due to acute renal failure and respiratory depression (pCO 2 ele-
vated). Her arterial oxygenation is reduced due to hypoventilation and pneumonia. She also
has a compartment syndrome in her arm due to massive swelling of her damaged muscles.
This patient has life-threatening hyperkalaemia with electrocardiogram (ECG) changes.
The ECG changes of hyperkalaemia progress from the earliest signs of peaking of the
T-wave, P-wave flattening, prolongation of the PR interval through to widening of the QRS
complex, a sine-wave pattern and ventricular fibrillation. Emergency treatment involves
intravenous calcium gluconate which stabilizes cardiac conduction, and intravenous
insulin/glucose, intravenous sodium bicarbonate and nebulized salbutamol, all of which
temporarily lower the plasma potassium by increasing the cellular uptake of potassium.
However, these steps should be regarded as holding measures while urgent dialysis is
being organized.
The chest X-ray and clinical findings indicate consolidation of the left lower lobe. This
patient should initially be managed on an intensive care unit. She will require antibiotics
for her pneumonia and will require a naloxone infusion or mechanical ventilation for her
respiratory failure. The patient should have vigorous rehydration with monitoring of her
central venous pressure. If a good urinary flow can be maintained, urinary pH should be
kept at!7.0 by bicarbonate infusion which prevents the renal toxicity of myoglobin. This
patient also needs to be considered urgently for surgical fasciotomy to relieve the com-
partment syndrome in her arm.
In the longer term, the patient needs counselling and with her boyfriend should be offered
access to drug-rehabilitation services. They should also be offered testing for blood-borne
viruses (hepatitis B and C and HIV).
- Acute hyperkalaemia is a life-threatening emergency.
- A very high creatine kinase level is diagnostic of rhabdomyolysis.
- As statins are now so widely used, they have become a common cause of rhabdomyoly-
sis, especially when used in high dose and in combination with ciclosporin. - Aggressive fluid replacement and a forced alkaline diuresis can prevent renal damage in
rhabdomyolysis if started early enough.