Multigas monitoring: real-time breath-by-breath monitoring of inspired and expired gas concentration

Measuring real-time, in-line breath-by-breath of inspired and expired gas concentrations has become standard of care during general anaesthesia and intensive care. The increasing interest in low and minimal flow anaesthesia has further stimulated interest in multigas monitoring during anaesthesia. Today both conventional sidestream and a compact mainstream multigas monitor are available which provide inspired and expired, end-tidal, oxygen, carbon dioxide and anaesthetic gas concentrations.

by Prof. Jan Jakobsson

Vital function
Adequate ventilation, proper oxygenation and eliminating carbon dioxide are fundamental elements to ensure vital functioning. Oxygen saturation assessed by pulse oximetry, SpO₂, has become one of the vital signs along with heart rate, blood pressure, respiratory rate and body temperature. Monitoring end-tidal carbon dioxide is a similar non-invasive simple way to gain real time information about ventilation. The end-tidal carbon dioxide reflects the arterial CO₂ tension, which in patients without profound lung pathology, is an accepted way to follow and adjust ventilation, for instance during anaesthesia. End-tidal carbon dioxide concentrations are measured directly at a patient