Physiologic dead space assessment: field of dreams or clinical paradigm?

In this issue of RESPIRATORY CARE, Siobal and colleagues report on the correlation, precision, and bias of calculated physiologic dead space, determined using the volumetric capnography module available in the Dräger XL ventilator, compared to other methods (metabolic analyzer and volumetric CO2 monitor).1 It is important to note that the investigators choose comparative technologies that reflect the standard of care for monitoring the ratio of dead space to tidal volume (VD/VT) at many institutions. Volumetric capnography is a relatively new addition to mechanical ventilators. Through their investigation, Siobal and colleagues demonstrate a high degree of association between the VD/VT derived through the Dräger ventilator module (using volumetric capnography) and other comparative technologies (Deltatrac, Metascope, Vmax Encore, and NICO2).