HYPOTHESIS: We hypothesized that late pulmonary dead space fraction (Fd(late)) 
would be a useful tool to screen for pulmonary embolism (PE) in a group of 
surgical patients, including patients who required mechanical ventilation and 
patients with adult respiratory distress syndrome.
DESIGN: We prospectively calculated Fd(late) in patients with suspected PE who 
underwent pulmonary angiography.
SETTING: University-based, level I trauma center.
MAIN OUTCOME MEASURE: Ability of Fd(late) to identify patients with PE.
RESULTS: Twelve patients had 14 angiograms for suspected PE. The Fd(late) was 
0.12 or above in all 5 patients who had PE; 4 required mechanical ventilation. 
The Fd(late) values were below 0.12 in 8 of 9 patients without PE. Four patients 
had adult respiratory distress syndrome. The Fd(late) had 100% sensitivity and 
89% specificity for the detection of PE.
CONCLUSIONS: The Fd(late) is a valuable tool for bedside screening of PE in 
surgical patients. We were able to accurately detect all PEs.