Can a NICO monitor substitute for thermodilution to measure cardiac output in patients with coexisting tricuspid regurgitation?

Imakiire, Naka; Omae, Takeshi; Matsunaga, Akira; Sakata, Ryuzo; Kanmura, Yuichi

PURPOSE The validity of measuring cardiac output (CO) using thermodilution via pulmonary artery catheterization in the presence of tricuspid regurgitation (TR) remains controversial. METHODS We compared the accuracy and precision of a non-invasive cardiac output (NICO) monitor and of thermodilution with those of transesophageal echocardiography (TEE) to measure CO in 50 patients who underwent elective valvoplasty to treat TR (26 mild and 24 moderate-to-severe) and in 25 normal controls (without TR). We used TEE as a reference method to measure CO and to intraoperatively grade TR. RESULTS The differences between NICO monitor and TEE measurements in patients without TR and in those with mild and with moderate-to-severe TR were -0.17 +/- 0.88 (n = 150, r (2) = 0.75), -0.16 +/- 0.82 (n = 158, r (2) = 0.78), and 0.17 +/- 0.91 L/min (n = 155, r (2) = 0.78), respectively. The differences between bolus thermodilution cardiac output and TEE measurements in patients without TR and in those with mild and with moderate-to-severe TR were -0.08 +/- 0.55 (r (2) = 0.88), 0.05 +/- 0.61 (r (2) = 0.86), and 0.43 +/- 1.37 L/min (r (2) = 0.58), respectively. CONCLUSION These findings demonstrate that measuring CO using the thermodilution technique is less accurate in patients with moderate-to-severe TR and that the NICO monitor is more accurate for such patients. We postulate that the NICO monitor measures CO more accurately and reproducibly than thermodilution in patients with coexisting TR.