RELIABILITY OF A NEW-GENERATION TRANSESOPHAGEAL DOPPLER DEVICE FOR CARDIAC-OUTPUT MONITORING

A new generation continuous-wave transesophageal Doppler (TED) device for cardiac output (CO) monitoring (Accucom 2, Datascope), which displ ays aortic blood flow velocity in real time, was evaluated by 140 simu ltaneous comparisons with thermodilution (TD) in 16 patients early aft er coronary artery bypass surgery. The aim was to determine whether th is technologic advancement improves the accuracy of COTED assessment. Absolute COTED values showed a considerable scatter as compared to COT D [COTED = 1.77 + 0.75-COTD (L/min), r = 0.521. The bias, i.e., the me an of individual CO differences (COTD - COTED) was -0.37 +/- 1.70 L/mi n (SD). In contrast, relative CO changes (DELTACO, % of preceding valu e) showed a satisfactory agreement between TED and TD [DELTACOTED = 1. 04 + 0.91 . DELTACOTD (%), r = 0.84, n = 124], the bias (DELTACOTD - D ELTACOTED) being -0.66 +/- 9.72%. In 8 of 124 situations (6.45%), howe ver, significant COTED changes opposite in direction to that of signif icant COTD changes occurred. This frequency was significantly greater (P < 0.01) than the ideal frequency of 0%. The agreement between DELTA COTD and DELTACOTED improved (P < 0.05) when the aortic diameter chang es induced by changes in mean arterial pressure were considered [DELTA COTED(MAPC) = 1.10 + 0.95-DELTACOTD (%), r = 0.87, n = 124]. Compared with previous results, the reliability of the second generation device to monitor relative CO changes was considerably improved. Provided th at the aortic blood flow velocity signal was stable and free from any disturbances, the second generation TED device may be regarded accepta ble for CO trend monitoring in sedated, paralyzed patients. Absolute C OTED values, however, still showed a high scatter compared to COTD; th e second generation TED device thus still is unsuitable to accurately measure absolute CO values.