Am. J. Respir. Crit. Care Med., Vol 150, No. 3, Sep 1994, 770-775.
Measurement of lung volume and DLCO in acute respiratory failure
PD Macnaughton and TW Evans
National Heart and Lung Institute, Department of Anaesthesia and Intensive Care, Royal Brompton National Heart and Lung Hospital, London, United Kingdom.
We have undertaken rebreathing measurements of functional residual capacity
(FRC), carbon monoxide diffusing capacity (DLCO), and diffusing coefficient
(KCO) during positive pressure ventilation in 15 patients with adult
respiratory distress syndrome (ARDS). Measurements of oxygenation
(PaO2:FIO2 ratio) and lung injury score (LIS) were also recorded. Eight
patients subsequently died (mortality of 53%). There was no significant
difference in mean FRC, PaO2:FIO2, or LIS at presentation between survivors
and nonsurvivors. However, both DLCO and KCO at presentation were
significantly greater in survivors than nonsurvivors. In a separate study
of nine patients with less severe lung injury, pulmonary capillary blood
volume, derived from values of DLCO measured at two different values of
FIO2, correlated with invasive pulmonary vascular resistance (PVR)
measurements (r = 0.84, p < 0.01). DLCO measurements can be successfully
undertaken in patients being ventilated with acute lung injury and may be a
useful, noninvasive method of assessing the pulmonary circulation. The
lowest values of DLCO were recorded in patients who subsequently did not
survive.
