Noninvasive technologies for tissue perfusion.
As outlined in Table 1, the nonthermodilution techniques available to measure cardiac output are noninvasive and clinically applicable to a variable degree. The truly noninvasive monitors are bioimpedance and CO2 re-breathing. The latter, however, requires the patient to be intubated, and the former continues to be evaluated with regard to correlation with the thermodilution standard. Esophageal Doppler devices are relatively noninvasive in that they do not require vascular cannulation, but they do require an immobile patient and some user expertise. Pulse contour analysis requires an arterial catheter, and two of the three available monitors require external calibration, while the third has not been validated adequately. The reader can see that all four approaches continue to be refined, with new analysis algorithms and monitors continuing to appear on the market. In the absence of true tissue oxygenation monitors, it seems likely that some or all of these alternatives to thermodilution will play a greater role in the care of patients where measurement of cardiac output is desired.
Ramsay
James
J
Anesthesiology Critical Care Medicine, Emory University School of Medicine, Emory University Hospital, 1364 Clifton Road, Atlanta, GA 30322, USA. james.ramsay@emoryhealthcare.org
D001783:Blood Flow Velocity; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism; D002302:Cardiac Output / Q000502:physiology*; D002407:Catheterization, Swan-Ganz / Q000379:methods; D004452:Echocardiography; D017548:Echocardiography, Transesophageal; D017097:Electric Impedance; D006801:Humans; D008991:Monitoring, Physiologic / Q000295:instrumentation; D010101:Oxygen Consumption; D013815:Thermodilution / Q000379:methods
D002245:Carbon Dioxide