Noninvasive hemodynamic monitoring
The pulmonary artery catheter (PAC) has been the diagnostic gold standard for: shock conditions, right v left dysfunction as well as continuous cardiac output monitoring, since its1970 debut. However, controversy regarding the risks and benefits of using PAC continues. Less invasive techniques for evaluating cardiac output exist but there are reliability issues. Comorbid conditions can introduce variables that may not be accounted for with non-invasive techniques.
Transesophogeal echocardiography (TEE) has replaced some Pulmonary Artery Catheter Thermodilution (PAC TD) use but TEE/PAC TD correlation of adult post-cardiothoracic surgery patient hemodynamic state was not shown to be reliable in a 2017 study by Power et al. Current evidence does not support interchangeability between TEE and PAC TD when measuring cardiac output (Wetterslev M. 2016). TEE is the preferred screening tool for suspected cases of pulmonary hypertension because it is noninvasive (Kanwar 2021). - Volume clamp method - employs a finger pressure cuff that rapidly oscillates pressure within the cuff. A photo-plethysmograph built into the cuff measures arterial volume and computer varies cuff pressure to hold the arterial volume stable an algorithm computes stroke volume, mean arterial pressure, cadriac output, cardiac index, and systemic vascular resistance. A 2018 study by Wagner showed good CO ageement between PAC thermodilution and volume clamp method among post-operative cardiothoracic patients.
- Electrical bioimpedance measures the resistance to electrical current (impedance) changes during the cardiac cycle owing to the fluctuating blood volume in the thorax. Several studies have demonstrated a lack of precision .
- Pulse wave transit time is the time that the stroke volume travels from the heart to the periphery, and can be measured as the time difference between the R top in the electrocardiogram and the start of the plethysmographic waveform obtained by pulse oximetry. The pulse wave transit time is inversely correlated with stroke volume and thus the CO; that is it decreases when stroke volume and CO increase. Evidence for the use of the pulse wave transit time method is limited (de Keijze 2021).
References
de Keijze I.N., Scheeren T.W.L. (2021). Perioperative Hemodynamic Monitoring: An overview of current methods. Anesthesiology clinics. Retrieved January 4, 2022, from https://pubmed.ncbi.nlm.nih.gov/34392878/
Power, P., Bone, A., Simpson, N., Yap, C. H., Gower, S., & Bailey, M. (2017). Comparison of pulmonary artery catheter, echocardiography, and arterial waveform analysis monitoring in predicting the hemodynamic state during and after cardiac surgery. International journal of critical illness and injury science, 7(3), 156–162. https://doi.org/10.4103/2229-5151.214411
Saugel B., Cecconi M.,et al. (2015) Noninvasive continuous cardiac output monitoring in perioperative and intensive care medicine. Br J Anaesth. 2015; 114: 562-575
Senoner, T.; Velik-Salchner, C.; Tauber, H. The Pulmonary Artery Catheter in the Perioperative Setting: Should It Still Be Used?. Diagnostics 2022, 12, 177. https://doi.org/ 10.3390/diagnostics12010177
Wagner JY, Körner A, Schulte-Uentrop L, Kubik M, Reichenspurner H, Kluge S, Reuter DA, Saugel B. A comparison of volume clamp method-based continuous noninvasive cardiac output (CNCO) measurement versus intermittent pulmonary artery thermodilution in postoperative cardiothoracic surgery patients. J Clin Monit Comput. 2018 Apr;32(2):235-244. doi: 10.1007/s10877-017-0027-x. Epub 2017 May 24. PMID: 28540614.
Wetterslev M, Møller-Sørensen H, Johansen RR, Perner A. Systematic review of cardiac output measurements by echocardiography vs. thermodilution: the techniques are not interchangeable. Intensive Care Med. 2016 Aug;42(8):1223-33. doi: 10.1007/s00134-016-4258-y. Epub 2016 Mar 1. PMID: 26932349.
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