There was good correlation between calculated by the CO(2)SMO and in the exhaust collected gas (mean bias 0.08). There was good correlation between the two methods of measurement (VCAP vs corrected r(2) = 0.90 P < 0.001, VCAP vs uncorrected r(2) = 0.90, P < 0.001). The study demonstrated good agreement between physiological V(D)/V(T) calculated by VCAP and corrected (mean bias 0.03), and uncorrected (mean bias 0.02) Bohr-Enghoff method. P(Ē(CO(2))) was measured in the chamber following correction for compressed gas. Exhaust ventilator gas was collected in a 10-l mixing chamber.

The calculated value of P(Ē(CO(2))) was also recorded from the CO(2)SMO device. Single-breath CO(2) waveform areas under the curve were computed automatically by software to calculate physiological dead space. In total, 168 paired readings were taken. Dead space was calculated simultaneously using VCAP (CO(2)SMO) and the Bohr-Enghoff equation.

Prospective observational study of 48 mechanically ventilated adults ICU patients. Few studies have been conducted to directly compare dead space measured by VCAP and the DB method in critically unwell adults.

Volumetric capnography (VCAP) offers a relatively simple solution to calculating dead space. These factors make this method impractical in the critical care setting. Physiological dead space should be a routine measurement in ventilated patients but measuring dead space using the Douglas bag (DB) method is cumbersome and requires corrections for compressed ventilator gas.

Calculate physiological dead space