ICU Vivas · Acid–base

Equipment viva — the blood-gas analyser and what it measures

An equipment viva on the modern blood-gas analyser — its measuring electrodes and CO-oximetry, the distinction between the measured values (pH, PaCO2, PaO2, electrolytes, lactate, glucose, haemoglobin and its derivatives) and the derived values (bicarbonate, base excess, anion gap, oxygen saturation), the sources of error, and the arterial-versus-venous and pre-analytical pitfalls.