Mon22November1200AM 7

A 67-year-old woman was admitted to hospital with a tender, hot, right calf.

She had a longstanding history of congestive cardiac failure and was known to have chronic oedema of her left leg. The admitting doctor recorded a differential diagnosis of either deep vein thrombosis or cellulitis and started the patient on a treatment dose of low molecular weight heparin and booked a Doppler ultrasound scan of the affected leg.

While on the ward overnight, the nurses asked the senior house officer to review the patient as they felt that she was not well. On reviewing her, the SHO found that the patient was confused, febrile 39.0C, blood pressure 85/60 mmHg, pulse 120 beats per minute and regular, and respiratory rate 32 breaths per minute.

The area of erythema that had been present on the right lower leg on admission had extended to the mid-thigh.

In recognition of the acutely sick patient, which of the following is correct?

(Please select 1 option)

Arterial blood gas pH is superior to base excess in evaluating metabolic acidosis

The respiratory rate is a highly specific sign predicting underlying physiological disturbance Incorrect answer selected

A blood lactate level of >1.5 mmol/L is associated with an increased mortality This is the correct answer

The commonest clinical signs preceding cardiac arrest are tachycardia and hypotension

The degree of base excess disturbance correlates with intravascular fluid requirement

Explanation

The following can all be used to predict critical illness:

Abnormalities in heart rate

Temperature

Respiratory rate

Urine output, and

Conscious level.

All of these have a low specificity but a high sensitivity in detecting underlying physiological disturbance.

Most critically ill patients have signs of organ dysfunction that are usually due to underlying tissue hypoxia. The most common clinical signs prior to a cardiac arrest are respiratory distress (RR >25/min) and altered mental state.

Over 50% of patients requiring ICU present with with metabolic acidosis many with a raised blood lactate concentration. A raised lactate in associated with a higher mortality.

Base excess has been shown to be superior to pH in evaluating metabolic acidosis and in predicting subsequent complications.

A base excess of <-4 mmol/L has been associated with a mortality of 50-60%.

Answer Statistics

1

5%

2

47%

3

19%

4

20%

5

11%

Times answered: 296