Comparison of invasive and noninvasive measurements of indocyanine green plasma disappearance rate in critically ill patients with mechanical ventilation and stable hemodynamics

Objectives: We studied the correlation between invasive (aortic fiberoptic) and noninvasive (transcutaneous sensor) measurements of indocyanine green (ICG) plasma disappearance rate (PDR) in critically ill patients. Design and setting: Prospective clinical study in a surgical intensive care unit of a university hospital. Patients: 16 critically ill patients with adult respiratory distress syndrome (n = 8), sepsis/septic shock (n = 6), subarachnoid hemorrhage (n = 1), or severe head injury (n = 1). Measurements and results: We analyzed 16 pairs of simultaneous ICG PDR measurements. All patients were deeply sedated and mechanically ventilated. Each patient received a 4-F aortic catheter with an integrated fiberoptic and thermistor connected to a computer system for automatic calculation of invasive ICG PDR (PDRINV). An ICG sensor was also attached to the nose wing and connected to a DDG2001 analyzer for noninvasive measurement (PDRNINV). Linear regression analysis revealed PDRNINV = 0.98 PDRINV+0.11 %/min (r = 0.94, p < 0.0001) with a mean bias of 0.2 +/- 2.0 %/min. Conclusion: Noninvasive measurements of ICG PDR are very highly correlated with values derived from an invasive fiberoptic-based reference technique.