Radial Artery Applanation Tonometry
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Radial Artery Applanation Tonometry for Continuous Noninvasive Cardiac Output Measurement: A Comparison With Intermittent Pulmonary Artery Thermodilution in Patients After Cardiothoracic Surgery Julia Y. Wagner, MD1; Harun Sarwari1; Gerhard Schön, MSc2; Mathias Kubik, MD3,4; Stefan Kluge, MD3; Herrmann Reichenspurner, MD4; Daniel A. Reuter, MD1; Bernd Saugel, MD1 Objectives: Radial artery applanation tonometry allows completely a pulmonary artery catheter (PAC-CO) with regard to accuracy, noninvasive continuous cardiac output estimation. The aim of the precision of agreement, and trending ability. present study was to compare cardiac output measurements Design: A prospective method comparison study. obtained with applanation tonometry (AT-CO) using the T-Line Setting: The study was conducted in a cardiosurgical ICU of a system (Tensys Medical, San Diego, CA) with cardiac output German university hospital. measured by intermittent pulmonary artery thermodilution using Patients: We performed cardiac output measurements in 50 patients after cardiothoracic surgery. Interventions: None. 1Department of Anesthesiology, Center of Anesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Ham- Measurements and Main Results: Three independent sets of burg, Germany. three consecutive thermodilution measurements (i.e., PAC- 2Department of Medical Biometry and Epidemiology, University Medical CO) each were performed per patient, and AT-CO was mea- Center Hamburg-Eppendorf, Hamburg, Germany. sured simultaneously. The average of the three thermodilution 3 Department of Intensive Care Medicine, University Medical Center Ham- cardiac output measurements was compared with the aver- burg-Eppendorf, Hamburg, Germany. age of the corresponding three AT-CO values resulting in 150 4Department of Cardiovascular Surgery, University Heart Center Ham- burg, Hamburg, Germany. paired cardiac output measurements. In 13 patients, cardiac Dr. Wagner and Sarwari contributed equally to this work. output–modifying maneuvers performed for clinical reasons Tensys Medical (San Diego, CA) provided the technical equipment for additionally allowed to evaluate trending ability. For statistical the study. analysis, we used Bland-Altman analysis, the percentage error, Dr. Wagner received grant support from Tensys Medical, San Diego, four-quadrant plot, and concordance analysis. Mean PAC-CO CA, and received support for travel from CNSystems Medizintechnik was 4.7 ± 1.2 L/min and mean AT-CO was 4.9 ± 1.1 L/min. The AG, Graz, Austria (refunds of travel expenses), and from Tensys Medi- cal, San Diego, CA (refunds of travel expenses). Dr. Kluge served as a mean of differences was –0.2 L/min with 95% limits of agree- board member for Astellas, Gambro, Gilead, MSD, NovaLung, Novartis, ment of –1.8 to + 1.4 L/min. The percentage error was 34%. and Pfizer and lectured for Astellas, Biotest, Gambro, Gilead, MSD, The concordance rate was 95%. Novalung, Pfizer, Sedana, and Thermo Fisher Scientific. Dr. Reuter served as a board member for Pulsion Medical Systems (Medical Advi- Conclusions: Continuous cardiac output measurement using the sory Board); consulted for Masimo Corp; and lectured for Edwards, noninvasive applanation tonometry technology is basically fea- Fresenius, and B. Braun. Dr. Saugel received support for travel from sible in ICU patients after cardiothoracic surgery. The applanation Tensys Medical (San Diego, CA) (refunds of travel expenses), served as a board member, lectured, consulted for Pulsion Medical Systems SE tonometry technology provides cardiac output values with reason- (Feldkirchen, Germany) (member of the Medical Advisory Board); and able accuracy and precision of agreement compared with inter- received support for travel from CNSystems Medizintechnik AG (Graz, mittent pulmonary artery thermodilution measurements in a clinical Austria) (refunds of travel expenses); and received grant support from Tensys Medical (San Diego, CA) (unrestricted research grants). The study setting and is able to reliably track cardiac output changes remaining authors have disclosed that they do not have any potential induced by cardiac output–modifying maneuvers. (Crit Care Med conflicts of interest. 2015; XX:00–00) For information regarding this article, E-mail: [email protected] Key Words: cardiac output; critical care; hemodynamic monitoring; Copyright © 2015 by the Society of Critical Care Medicine and Wolters pulmonary artery catheter; T-Line Kluwer Health, Inc. All Rights Reserved. DOI: 10.1097/CCM.0000000000000979 Critical Care Medicine www.ccmjournal.org 1 Copyright © 2015 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved. Wagner et al ardiac output (CO) is an essential variable when it operating room to the cardiosurgical ICU. Independent of comes to adequately monitoring and optimizing a the study, all medical decisions regarding analgosedation and Cpatient’s hemodynamics in the ICU and during inter- hemodynamic management during the postoperative period mediate-risk and high-risk surgical procedures (1, 2). were at the discretion of the treating ICU physician. This In the 1970s, the pulmonary artery catheter (PAC) devel- included the need for IV opioids for analgesia and propofol oped by Harold Jeremy Swan and William Ganz became avail- for sedation and the timing of extubation. The patient’s hemo- able for the invasive CO measurement by thermodilution (3, dynamic state and fluid responsiveness were evaluated (e.g., 4). Despite its decline approximately 30 years later triggered by using passive leg raising test) and optimized with IV fluids and studies demonstrating an unfavorable risk-benefit profile (5, catecholamines. Each diagnostic and therapeutic intervention 6), the PAC still proves to be of outstanding importance in dis- was based on the ICU physicians’ medical decisions indepen- tinct clinical situations (7) and is still considered as the clinical dent from the study measurements. criterion standard method for measuring CO (8). After arrival in the ICU, patients were connected to the AT During the years after the decrease in routine PAC use, a num- study device (T-Line 400 monitor). A bracelet was placed on ber of alternatives for invasive, less-invasive, and noninvasive CO the patient’s wrist equipped with an electromechanical system measurements have been introduced and evaluated (9–14). and a sensor that moves over the radial artery in order to find One of the novel technologies that provides continuous the optimal applanation pressure as described before (21, 22). completely noninvasive CO monitoring is the radial artery When the optimal signal is available, the T-Line monitor pro- applanation tonometry (AT). One commercially available vides a continuous arterial waveform. In order to compensate device using the AT technology for the assessment of hemo- for height differences between the study limb and the patient’s dynamic variables is the T-Line system (Tensys Medical, San heart level, the level function of the T-Line system was applied. Diego, CA). The AT technology’s ability to measure blood pres- By using the level function one levels the T-Line electronically sure continuously and noninvasively has already been demon- by entering on the T-Line monitor’s touchscreen the vertical strated (15–20). Furthermore, our group recently described height of the study limb above or below the patient’s heart level. and evaluated an algorithm for CO determination based on AT After entering the patient’s biometric data (height, weight, in a proof-of-concept analysis using impeccable arterial wave- age, and gender), the AT system’s monitor displays CO values forms of ICU patients selected from a database (12). derived from pulse contour analysis using a proprietary auto- In the present study, we investigate the accuracy, precision calibrating algorithm. of agreement, and trending ability of the AT technology for The study measurements were performed at three differ- the measurement of CO in comparison with pulmonary artery ent time points during the postoperative period. The intervals thermodilution as the clinical criterion standard method in between the time points differed depending on the clini- postoperative cardiothoracic surgery patients. cal routine events. At each time point, one pulmonary artery thermodilution measurement using the PAC consisted of five injections of 10-mL ice-cold sodium chloride. The five cor- MATERIALS AND METHODS responding AT CO measurements (AT-CO) were recorded Patients, Inclusion/Exclusion Criteria, and Study simultaneously. In order to avoid an impact due to discrep- Measurements ancies between the single pulmonary artery thermodilution Our study was conducted in a cardiosurgical ICU of a Ger- measurements, the average of the three of five closest thermo- man university hospital (University Medical Center Ham- dilution CO measurements (PAC-CO) was used for compari- burg-Eppendorf, Hamburg, Germany). The ethics committee son with the average of the corresponding three AT-CO values. (Ethikkommission der Ärztekammer Hamburg) approved the Immediately after the patient monitor displayed the thermo- study. We obtained written informed consent from all patients dilution-derived CO value, the corresponding CO value mea- prior to study enrollment. sured with AT was recorded using screen shots. The study included patients aged at least 18 years, who In a subgroup of the study patients, the ICU physician in underwent nonemergency cardiothoracic surgery,