Noninvasive Cardiopulmonary Monitor Research Articles

Noninvasive, simultaneous, and continuous measurements of stroke volume and tidal volume using EIT: feasibility study of animal experiments

Currently, there is no noninvasive method available for simultaneous measurements of tidal volume and stroke volume. Electrical impedance tomography (EIT) has been used for regional lung ventilation imaging. Cardiac EIT imaging, however, has not been successful due to the technical difficulty in extracting weak cardiogenic components. Instead of regional imaging, in this paper, we use the EIT technique to simultaneously measure two global variables of tidal volume and stroke volume. Time-varying patterns of boundary voltage data originating from lung ventilation and cardiac blood flow were extracted from measured boundary voltage data using the principal component analysis (PCA) and independent component analysis (ICA). The source consistency theory was adopted to separately synthesize time-series of boundary voltage data associated with lung ventilation and cardiac blood flow. The respiratory volume signal (RVS) and cardiac volume signal (CVS) were extracted from reconstructed time-difference EIT images of lung ventilation and cardiac blood flow, respectively. After calibrating the volume signals using the mechanical ventilator and the invasive transpulmonary thermodilution (TPTD) method, tidal volume and stroke volume were computed as valley-to-peak values of the RVS and CVS, respectively. The difference in the tidal volume data between EIT and mechanical ventilator was within ± 20 ml from six pigs. The difference in the stroke volume data between EIT and TPTD was within ± 4.7 ml from the same animals. The results show the feasibility of the proposed method as a new noninvasive cardiopulmonary monitoring tool for simultaneous continuous measurements of stroke volume and tidal volume that are two most important vital signs.

Comparison of cardiac output (CO) measurement before and after cardiopulmonary bypass: bolus thermodilution (TDco) and noninvasive partial CO2 rebreathing (NICO)

NICO is a noninvasive cardiopulmonary monitor that provides an alternative to invasive TDco for measurement of CO. NICO uses a differential form of the Fick equation (change in CO2 excretion and end-tidal CO2, in response to a brief period of partial rebreathing) to provide noninvasive estimates of the CO [1]. The objective of this study was to compare the degree of agreement in measurements of CO using NICO and TDco, at predetermined intervals in patients undergoing coronary artery bypass graft surgery (CABG).

Assessment of the agreement between cardiac output measured by thermal filament continuous thermodilution (CCO) and noninvasive partial CO2 rebreathing (NICO) with particular reference to ETCO2 levels

Cardiac output (CO) is an important hemodynamic parameter and its continuous measurement has the potential to enable early recognition of hemodynamic trends and provide earlier therapeutic response. NICO is a new noninvasive cardiopulmonary monitor that provides an alternative to invasive CCO for measurement of CO. NICO uses a differential form of the Fick equation (change in CO2 excretion and end-tidal CO2, in response to a brief period of partial rebreathing) to provide noninvasive estimates of CO [1]. The accuracy and reliability of NICO as a function of the end-tidal CO2 (ETCO2) levels of the patient has not been studied. The purpose of this study was to determine if ETCO2 levels affect the degree of agreement between NICO and CCO.

Noninvasive Cardiovascular and Respiratory System Monitoring in Laparoscopic Cholesystectomy

Background: The deleterious cardiopulmonary side effects immediately after positioning in revetse Trendelenburg and CO₂ intra-abdominal insufflation during a laparoscopic cholecystectomy are well tolerated in healthy patients but can lead to serious morbidity and mortality in patients with a limited cardiopulmonary reserve. Using a continuous and non-invasive cardiac output monitor based on partial CO₂ ebreathing method, we investigated the immediate cardiopulmonary changes caused by positioning in reverse Trendelenburg and CO₂intra-abdominal insufflation during a laparoscopic cholecystectomy, and assessed the applicability of the partial CO₂rebreathing method for the measurement of cardiac output in a laparoscopic cholecystectomy. Methods: The investigation was carried out on 11 patients undergoing a laparoscopic cholesystectomy. The control values of cardiac index (CI), cardiac output (CO), mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), systemic vascular resistance (SVR), dynamic compliance (Cdyn), airway resistance (Raw), peak inspiratory pressure (PIP) and end tidal CO₂partial pressure (PETCO₂) were measured in the supine position after induction with target-controlled infusion of propofol (5 pg/ ml). Five minutes after positioning in reverse Trendelenburg and CO insufflation, the same cardiopulmonay variables were measured and compared with the control values. Results: CI, CO and CVP were reduced 33.3%, 31.9% and 29.0%, respectively (P < 0.05). MAP and SVR were increased 39.8% and 154.1%, respectively (P < 0.05). Cdyn was reduced 38.0% (P < 0,05). Raw and PIP were increased 22.8%, and 34.8%, respectively (P < 0.05), whereas HR and PETCO₂ remained unchanged. Conclusions: The non-invasive cardiopulmonary monitor using partial CO₂ rebreathing method, could be used with ease and safety in a laparoscopic cholecystectomy.

Invasive and noninvasive cardiopulmonary monitoring of acute circulatory dysfunction and shock

Invasive and noninvasive cardiopulmonary monitoring of acute circulatory dysfunction and shock