Introduction
Thermodilution (TD) is a gold standard for cardiac output (CO) measurement in critically ill patients [1]. Although transpulmonary thermodiluation is less invasive than the Swan-Ganz catheter, it still requires an arterial and deep venous line. This study will compare intermittent bolus transpulmonary TDCO with continuous CO (CCO) obtained by pulse contour analysis (PiCCO2; Pulsion Medical Systems) and non-invasive CO (NexCO) measurement via finger cuff using Finapres technology (Nexfin BMEYE).
Methods
A prospective study in 45 patients (43 mechanically ventilated, 32 male). Age 57.6 ± 19.4, BMI 25.3 ± 4.4, SAPS II 51.5 ± 16.9, APACHE II 25.3 ± 10.3 and SOFA score 9.4 ± 3.3. In an 8-hour period, simultaneous CCO and NexCO measurements were obtained every 2 hours while simultaneous TDCO and NexCO were obtained every 4 hours. The CCO and NexCO values were recorded within 5 minutes before TDCO was determined. Statistical analysis was performed using Pearson correlation and Bland-Altman analysis.
Results
In total, 585 CO values were obtained: 225 paired CCO-NexCO; 135 paired CCO-TDCO and 135 NexCO-TDCO. Thirty-five patients received norepinephrine at a dose of 0.2 ± 0.2 μg/kg/minute (range 0.02 to 1). TDCO values ranged from 2.4 to 14.9 l/minute (mean 6.6 ± 2.2), CCO ranged from 1.8 to 15.6 l/minute (6.4 ± 2.3) and NexCO from 0.8 to 14.9 l/minute (6.1 ± 2.3). The Pearson correlation coefficient comparing NexCO with TDCO and CCO was similar with an R2 of 0.68 and 0.71 respectively. Bland-Altman analysis comparing NexCO with TDCO revealed a mean bias ± 2SD (limits of agreement (LA)) of 0.4 ± 2.32 l/minute (with 36.1% error) while analysis of NexCO versus CCO showed a bias (± LA) of 0.2 ± 2.32 l/minute (37% error). TDCO was highly correlated with CCO (R2 = 0.95) with bias 0.2 ± 0.86 (% error 13.3). The MAP values obtained ranged from 43 to 140 mmHg (83 ± 17) for PiCCO2 and from 44 to 131 (85 ± 17) for Nexfin. The MAP obtained with Nexfin correlated well with invasive MAP via PiCCO2 (R2 = 0.89) with a bias (± LA) of 2.3 ± 12.4 (% error 14.7).
Conclusions
These preliminary results indicate that in unstable critically ill patients CO and MAP can be reliably monitored non-invasively with Nexfin technology. Although TPTD remains a gold stand for the measurement of CO in ICU patients, Nexfin non-invasive monitoring may provide useful information in the emergency or operating room when an arterial or CVL is not available.
References
Malbrain M, et al.: Cost-effectiveness of minimally invasive hemodynamic monitoring. In Yearbook of Intensive Care and Emergency Medicine. Edited by: Vincent J-L. Berlin: Springer-Verlag; 2005:603-631.
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Van de Vijver, K., Verstraeten, A., Gillebert, C. et al. Validation of non-invasive hemodynamic monitoring with Nexfin in critically ill patients. Crit Care 15 (Suppl 1), P75 (2011). https://doi.org/10.1186/cc9495
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DOI: https://doi.org/10.1186/cc9495