Validation of noninvasive pulse contour cardiac output using finger arterial pressure in cardiac surgery patients requiring fluid therapy

Introduction

Nexfin (Edwards Lifesciences, Irvine, CA) allows for noninvasive continuous monitoring of blood pressure (ABP_NI) and cardiac output (CO_NI) by measuring finger arterial pressure (FAP). To evaluate the accuracy of FAP in measuring ABP_NI and CO_NI as well as the adequacy of detecting changes in ABP and CO, we compared FAP to intra-arterially measured blood pressure (ABP_IA) and transpulmonary thermodilution (CO_TD) in postcardiac surgery patients during a fluid challenge (FC).

Methods

Twenty sedated patients post cardiac surgery were included, and 28 FCs were performed. Measurements of ABP and CO were simultaneously collected before and after an FC, and we compared CO and blood pressure.

Results

Finger arterial pressure was obtainable in all patients. When comparing ABP_NI with ABP_IA, bias was 2.7 mm Hg (limits of agreement [LOA], ± 22.2), 4.9 mm Hg (LOA, ± 13.6), and 4.2 mm Hg (LOA, ± 13.7) for systolic, diastolic, and mean arterial pressure, respectively. Concordance between changes in ABP_NI and ABP_IA was 100%. Mean bias between CO_NI and CO_TD was − 0.26 (LOA, ± 2.2), with a percentage error of 38.9%. Concordance between changes in CO_NI vs CO_TD and was 100%.

Conclusion

Finger arterial pressure reliably measures ABP and adequately tracks changes in ABP. Although CO_NI is not interchangeable with CO_TD, it follows changes in CO closely.