By Dr. Jürgen Fortin, CEO, CNSystems
Pulse Contour Analysis (PCA) for deriving complete Hemodynamics from continuous blood pressure wave (CNAP)
Pulse Contour Analysis (PCA)[1] derives important physiological information on preload, contractility, afterload and compliance of the heart from the well validated CNAP® Continuous Noninvasive Arterial Pressure Curve[2],[3]. By adding biometric patient data Stroke Volume (SV) and therefrom Continuous Noninvasive Cardiac Output (CNCO®), both essential hemodynamic markers, are calculated. Further hemodynamic parameters such as Systemic Vascular Resistance (SVR) as well as all indexed values SI, CI or SVRI are derived completing the hemodynamic picture.
Validation: CNCO® is clinically validated against invasive methods
Non-invasive continuous CNCO® is the non-invasive continuous cardiac output calculated from CNAP® Arterial Pressure as described above.
Accuracy of CNCO® compared to clinical standards such as invasive thermodilution (TD) or PiCCO is expressed as percentage error. In 1999, Critchley and Critchley suggested a percentage error of 30% or less[4]. In clinical practice, however, percentage errors of 40-45% are more realistic for the interchangeability between two CO-measurement methods (meta-analysis by Peyton and Chong[5]).
Trending ability is the precise tracking of changes in CO. According to Critchley, Lee and Ho, reliable trending ability[6] is indicated by concordance rates of > 90%. Vincent and colleagues state that following hemodynamic trends may be more important than absolute values[7].
CNCO® shows both high accuracy as well as high trending ability (precision) compared to the invasive clinical standards thermodilution and PiCCO fulfilling all Critchley criteria:
Bland-Altman plots show
- Small bias and narrow limits of agreement
- Percentage errors ≤ 30% (according to strict Critchley standard [8],[9])
- Concordance rates ≥ 90% (according to standard [10])
Read more on CNAP accuracy here and here.
Benefit of continuous BP, CO & SVR in research (examples)
Blood pressure, cardiac output and vascular resistance are used to differentiate between challenge and threat states (positive and negative stress)[11],[12] and to quantify emotional response[13] in psychophysiological studies. A challenging situation causes a far bigger rise in cardiac output than a threating state. Total peripheral resistance rises in threat state but shows strong decrease in the challenging situation.
CNCO® is available with the CNAP® HD feature, currently only available in Europe.
For more information on CNAP, to include references to studies and research and plots, click here.
[1] https://en.wikipedia.org/wiki/Cardiac_output#Pulse_Pressure_methods
[2] Jeleazcov C et. al. Precision and accuracy of a new device (CNAP®) for continuous noninvasive arterial blood pressure monitoring: assessment during general anaesthesia. BJA. 2010; 105(3):264-272
[3] Biais, M. et. al. Continuous non-invasive arterial pressure measurement: Evaluation of CNAPTM device during vascular surgery Ann Fr Anesthesia
[4] Critchley, L. A., & Critchley, J. A. (1999). A meta-analysis of studies using bias and precision statistics to compare cardiac output measurement techniques. Journal of clinical monitoring and computing, 15(2), 85–91
[5] Peyton PJ, Chong SW: Minimally invasive measurement of cardiac output during surgery and critical care. Anesthesiology 2010; 113:1220-35
[6] Critchley LA, Lee A, Ho AMH: A critical review of the ability of continuous cardiac output monitors to measure trends in cardiac output. Anesth Analg 2010; 111:1180-92.
[7] Vincent JL et al.: Clinical review: Update on hemodynamic monitoring – a consensus of 16. Critical Care 2011, 15:229.
[8] Critchley, L. A., & Critchley, J. A. (1999). A meta-analysis of studies using bias and precision statistics to compare cardiac output measurement techniques. Journal of clinical monitoring and computing, 15(2), 85–91
[9] Peyton PJ, Chong SW: Minimally invasive measurement of cardiac output during surgery and critical care. Anesthesiology 2010; 113:1220-35.
[10] Critchley LA, Lee A, Ho AMH: A critical review of the ability of continuous cardiac output monitors to measure trends in cardiac output. Anesth Analg 2010; 111:1180-92.
[11] Kirby, L. D., & Wright, R. A. (2003). Cardiovascular correlates of challenge and threat appraisals: A critical examination of the Biopsychosocial Analysis. Personality and Social Psychology Bulletin, 7, 216-233.
[12] Tomaka, J., Blascovich, J., Kelsey, R. M., & Leitten, C. L. (1993). Subjective, physiological, and behavioral effects of threat and challenge appraisal. Journal of Personality and Social Psychology, 65, 248-260.
[13] Lackner, H. K., Weiss, E. M., Schulter, G., Hinghofer-Szalkay, H., Samson, A. C., & Papousek, I. (2013). I got it! Transient Cardiovascular Response to the Perception of Humor. Biological Psychology, 93, 33–40.
For more information on BIOPAC’s Noninvasive Blood Pressure monitoring and measurement systems and advanced functionality in the area of cardiovascular hemodynamics, to include CNAP noninvasive blood pressure systems, visit BIOPAC’s NIBP page or view BIOPAC’s NIBP amplifiers (MRI and small animal applications are also supported) and related equipment for a wide variety of research applications.
BIOPAC Systems, Inc. provides life science researchers and educators with data acquisition and analysis systems that inspire people and enable greater discovery about life. Visit us at www.biopac.com.
