Noninvasive Cardiac Output Research Articles

Evaluation of the Noninvasive Estimated Continuous Cardiac Output System for Pediatric Patients: A Prospective Observational Study.

The estimated continuous cardiac output (esCCO) system is a hemodynamic monitor that uses electrocardiograms and pulse oximeter waves to noninvasively estimate cardiac output. The coefficients for esCCO measurement have been established for adult patients, but the appropriate coefficients for pediatric patients are unclear. Therefore, this study determined esCCO coefficients for pediatric patients and validated the accuracy and tracking ability of a modified esCCO system. An initial study compared cardiac output measurements using transthoracic echocardiography and esCCO in 60 pediatric patients aged <15 years who underwent elective noncardiac surgery. Consequently, the coefficients for the esCCO measurements were redefined for pediatric patients. The main study compared cardiac output measurements between transthoracic echocardiography and modified esCCO in 80 pediatric patients. Measurements were performed pre- and postoperatively, and the accuracy and trending ability of the cardiac output measurements were evaluated using Bland-Altman analysis and a polar plot. The correlation coefficients between the modified esCCO and transthoracic echocardiography were 0.96 and 0.98 in the pre- and postoperative measurements, respectively. In Bland-Altman analysis, the bias (standard deviation [SD]), 95% limits of agreement, and percentage error were 0.03 (0.28), -0.53 to 0.60, and 18% in the preoperative measurement, and -0.04 (0.19), -0.42 to 0.35, and 15% in the postoperative measurement, respectively. The polar plot showed that the cardiac output changes were well tracked, with an angular bias (SD) of 2.9° (6.0°) and radial 95% limits of agreement ranging from -9.2° to 14.9°. Cardiac output measurement by esCCO with modified coefficients for pediatric patients showed high accuracy and tracking ability compared with cardiac output measurement by transthoracic echocardiography. This noninvasive cardiac output measurement could benefit perioperative hemodynamic monitoring in children.

Bioreactance noninvasive cardiac output monitoring in euvolemic adult horses subjected with 7.2% saline and 6% hydroxyethyl starch (130/0.4) solution infusions.

To compare the ability of bioreactance noninvasive cardiac output (BR-NICO) with thermodilution cardiac output (TDCO) for the measurement of cardiac output (CO) in healthy adult horses receiving 2 different IV volume replacement solutions. Prospective randomized crossover study from September to November 2021. University teaching hospital. Six university-owned adult horses. Horses were randomly assigned to receive 7.2% hypertonic saline solution (HSS) or 6% hydroxyethyl starch (130/0.4) solution (HETA). BR-NICO and TDCO were measured simultaneously at baseline, 10, 20, 30, 40, 50, 60, 90, and 120minutes before fluid administration and again at the same times after starting a bolus infusion of IV volume replacers. All solutions were administered within 10minutes. BR-NICO and TDCO were strongly correlated (Pearson r2=0.93; P<0.01). Regression analysis showed the relationship between TDCO and BR-NICO was BR-NICO=0.48×TDCO+0.6. For the corrected BR-NICO values, the Bland-Altman agreement mean bias and lower/upper limits of agreement were -0.62 and -5.3 to 3.9L/min, respectively. Lin's concordance (95% confidence interval) between methods was 0.894 (0.825-1.097). Compared with baseline, HSS increased the CO at 10 and 20minutes (TDCO and BR-NICO). Compared with baseline, HETA decreased the CO at 10 and 20minutes (TDCO and BR-NICO) and increased the CO at 90 (TDCO only) and 120minutes (TDCO and BR-NICO). BR-NICO strongly agreed with TDCO in the measurement of CO in healthy unsedated adult horses. HSS administration significantly increased CO in the first 30minutes, while HETA initially decreased CO at 10minutes but increased CO to above baseline values by 90minutes.

Occurrence of Low Cardiac Index During Normotensive Periods in Cardiac Surgery: A Prospective Cohort Study Using Continuous Noninvasive Cardiac Output Monitoring.

Continuous cardiac output monitoring is not standard practice during cardiac surgery, even though patients are at substantial risk for systemic hypoperfusion. Thus, the frequency of low cardiac output during cardiac surgery is unknown. We conducted a prospective cohort study at a tertiary medical center from July 2021 to November 2023. Eligible patients were ≥18 undergoing isolated coronary bypass (CAB) surgery with the use of cardiopulmonary bypass (CPB). Cardiac output indexed to body surface area (CI) was continuously recorded at 5-second intervals throughout surgery using a US Food and Drug Administration (FDA)-approved noninvasive monitor from the arterial blood pressure waveform. Mean arterial blood pressure (MAP) and central venous pressure (CVP) were also analyzed. Low CI was defined as <2 L/min/m2 and low MAP as <65 mm Hg. We calculated time with low CI for each patient for the entire surgery, pre-CPB and post-CPB periods, and the proportion of time with low CI and normal MAP. We used Pearson correlation to evaluate the relationship between CI and MAP and paired Wilcoxon rank sum tests to assess the difference in correlations of CI with MAP before and after CPB. In total, 101 patients were analyzed (age [standard deviation, SD] 64.8 [9.8] years, 25% female). Total intraoperative time (mean [SD]) with low CI was 86.4 (62) minutes, with 61.2 (42) minutes of low CI pre-CPB and 25.2 (31) minutes post-CPB. Total intraoperative time with low CI and normal MAP was 66.5 (56) minutes, representing mean (SD) 69% (23%) of the total time with low CI; 45.8 (38) minutes occurred pre-CPB and 20.6 (27) minutes occurred post-CPB. Overall, the correlation (mean [SD]) between CI and MAP was 0.33 (0.31), and the correlation was significantly higher pre-CPB (0.53 [0.32]) than post-CPB (0.29 [0.28], 95% confidence interval [CI] for difference [0.18-0.34], P < .001); however, there was substantial heterogeneity among participants in correlations of CI with MAP before and after CPB. Secondary analyses that accounted for CVP did not alter the correlation between CI and MAP. Exploratory analyses suggested duration of low CI (C <2 L/min/m2) was associated with increased risk of postoperative acute kidney injury (odds ratios [ORs] = 1.09; 95% CI; 1.01-1.13; P = .018). In a prospective cohort of patients undergoing CAB surgery, low CI was common even when blood pressure was normal. CI and MAP were correlated modestly. Correlation was higher before than after CPB with substantial heterogeneity among individuals. Future studies are needed to examine the independent relation of low CI to postoperative kidney injury and other adverse outcomes related to hypoperfusion.

Comparative Analysis of Muscle Activity and Circulatory Dynamics: A Crossover Study Using Leg Exercise Apparatus and Ergometer.

Background and Objectives: Bedridden patients are at a high risk of venous thromboembolism (VTE). Passive devices such as elastic compression stockings and intermittent pneumatic compression are common. Leg exercise apparatus (LEX) is an active device designed to prevent VTE by effectively contracting the soleus muscle and is therefore expected to be effective in preventing disuse of the lower limbs. However, few studies have been conducted on the kinematic properties of LEX. Therefore, this study aimed to compare the exercise characteristics of LEX with those of an ergometer, which is commonly used as a lower-limb exercise device, and examine its effect on the two domains of muscle activity and circulatory dynamics. Materials and Methods: This study used a crossover design in which each participant performed both exercises to evaluate the exercise characteristics of each device. Fifteen healthy adults performed exercises with LEX and an ergometer (Terasu Erugo, SDG Co., Ltd., Tokyo, Japan) for 5 min each and rested for 10 min after each exercise. Muscle activity was measured using surface electromyography (Clinical DTS, Noraxon, Scottsdale, AZ, USA), and circulatory dynamics were recorded using a non-invasive impedance cardiac output meter (Physioflow Enduro, Manatec Biomedical, Paris, France). The primary outcome was the mean percentage of maximum voluntary contraction (%MVC) of the soleus muscle during exercise. Results: The mean %MVC of the soleus muscle was significantly higher in the LEX group, whereas no significant differences were observed across the periods and sequences. Heart rate, stroke volume, and cardiac output increased during exercise and decreased thereafter; however, the differences between the devices were not significant. Conclusions: LEX may not only have a higher thromboprophylaxis effect, but also a higher effect on preventing muscle atrophy as a lower-extremity exercise device. Additionally, LEX could potentially be used safely in patients who need to be monitored for changes in circulatory dynamics.

A recommendation for the use of electrical biosensing technology in neonatology.

Non-invasive cardiac output monitoring, via electrical biosensing technology (EBT), provides continuous, multi-parameter hemodynamic variable monitoring which may allow for timely identification of hemodynamic instability in some neonates, providing an opportunity for early intervention that may improve neonatal outcomes. EBT encompasses thoracic (TEBT) and whole body (WBEBT) methods. Despite the lack of relative accuracy of these technologies, as compared to transthoracic echocardiography, the use of these technologies in neonatology, both in the research and clinical arena, have increased dramatically over the last 30 years. The European Society of Pediatric Research Special Interest Group in Non-Invasive Cardiac Output Monitoring, a group of experienced neonatologists in the field of EBT, deemed it appropriate to provide recommendations for the use of TEBT and WBEBT in the field of neonatology. Although TEBT is not an accurate determinant of cardiac output or stroke volume, it may be useful for monitoring longitudinal changes of hemodynamic parameters. Few recommendations can be made for the use of TEBT in common neonatal clinical conditions. It is recommended not to use WBEBT to monitor cardiac output. The differences in technologies, study methodologies and data reporting should be addressed in ongoing research prior to introducing EBT into routine practice. IMPACT STATEMENT: TEBT is not recommended as an accurate determinant of cardiac output (CO) (or stroke volume (SV)). TEBT may be useful for monitoring longitudinal changes from baseline of hemodynamic parameters on an individual patient basis. TEBT-derived thoracic fluid content (TFC) longitudinal changes from baseline may be useful in monitoring progress in respiratory disorders and circulatory conditions affecting intrathoracic fluid volume. Currently there is insufficient evidence to make any recommendations regarding the use of WBEBT for CO monitoring in neonates. Further research is required in all areas prior to the implementation of these monitors into routine clinical practice.

Hemodynamic Changes of Women with Preeclampsia Undergoing Spinal Anesthesia for Emergency Cesarean Section: A Prospective Observational Study

Abstract Background: Preeclampsia is a multisystem disorder in pregnancy and remains a significant cause of maternal morbidity and mortality. In this prospective observational study, we used a continuous noninvasive cardiac output monitor to investigate the changes in arterial blood pressure, cardiac output, systemic vascular resistance, stroke volume, and stroke volume variation during the immediate perioperative period. Materials and Methods: Women with preeclampsia undergoing emergency cesarean section under spinal anesthesia were recruited in this prospective observational study. Cardiac output and arterial blood pressures were measured by the Nexfin monitor. Cardiovascular parameters were recorded intraoperatively and up to 48 h postoperatively. The primary outcome was to examine the differences in cardiac output between the intraoperative and postoperative periods. Results: Thirty patients included in the data analysis had a mean age of 35.6 ± 5.2 years and gestation of 35.4 ± 2.1 weeks. Post-spinal anesthesia, 50% experienced hypotension. 26.7% had nausea, 10% vomited, and other events included shivering, reactive hypertension, and bradycardia. The use of spinal anesthesia was associated with a significant reduction in systolic (126.7 ± 16.9 vs. 142.0 ± 21.2 mm Hg, P &lt; 0.001), diastolic (71.2 ± 8.4 vs. 77.0 ± 11.3 mm Hg, P &lt; 0.001), mean arterial pressure (92.6 ± 12.2 vs. 103.7 ± 15.3 mm Hg, P &lt; 0.001), cardiac output, and stroke volume compared to postoperative readings. No significant difference was found in cardiac output, cardiac index, or systemic vascular resistance indices between the intraoperative and postoperative periods. Conclusion: Spinal anesthesia may have short-term hemodynamic changes in women with preeclampsia. Continuous noninvasive cardiac monitoring can be used to monitor specific cardiac hemodynamic parameters, which may resolve in the immediate postoperative period.

Continuous non-invasive measurement of cardiac output in neonatal intensive care using regional impedance cardiography: a prospective observational study

ObjectivesTo compare agreement between echocardiography and regional impedance cardiography (RIC)-derived cardiac output (CO), and to construct indicative normative ranges of CO for gestational age groups.Design, setting and participantsProspective cohort observational...

Comparison of cardiac output estimates obtained from the Antares oscillometric pulse wave analysis algorithm and from Doppler transthoracic echocardiography.

In cardiology, cardiac output (CO) is an important parameter for assessing cardiac function. While invasive thermodilution procedures are the gold standard for CO assessment, transthoracic Doppler echocardiography (TTE) has become the established method for routine CO assessment in daily clinical practice. However, a demand persists for non-invasive approaches, including oscillometric pulse wave analysis (PWA), to enhance the accuracy of CO estimation, reduce complications associated with invasive procedures, and facilitate its application in non-intensive care settings. Here, we aimed to compare the TTE and oscillometric PWA algorithm Antares for a non-invasive estimation of CO. Non-invasive CO data obtained by two-dimensional TTE were compared with those from an oscillometric blood pressure device (custo med GmbH, Ottobrunn, Germany) using the integrated algorithm Antares (Redwave Medical GmbH, Jena, Germany). In total, 59 patients undergoing elective cardiac catheterization for clinical reasons (71±10 years old, 76% males) were included. Agreement between both CO measures were assessed by Bland-Altman analysis, Student's t-test, and Pearson correlations. The mean difference in CO was 0.04 ± 1.03 l/min (95% confidence interval for the mean difference: -0.23 to 0.30 l/min) for the overall group, with lower and upper limits of agreement at -1.98 and 2.05 l/min, respectively. There was no statistically significant difference in means between both CO measures (P = 0.785). Statistically significant correlations between TTE and Antares CO were observed in the entire cohort (r = 0.705, P<0.001) as well as in female (r = 0.802, P<0.001) and male patients (r = 0.669, P<0.001). The oscillometric PWA algorithm Antares and established TTE for a non-invasive estimation of CO are highly correlated in male and female patients, with no statistically significant difference between both approaches. Future validation studies of the Antares CO are necessary before a clinical application can be considered.

Cardiac output calculation using the Liljestrand and Zander formula: is this method applicable during immediate transition after birth? — A post hoc analysis

The transition from intrauterine to extrauterine life is a critical period for neonates. Assessing the cardiovascular transition during this period immediately after birth is crucial but challenging. The present study compares adjusted estimated cardiac output values calculated by the Liljestrand and Zander formula (COest/adj LaZ) with non-invasively measured cardiac output values (CO-bioimpedance) during immediate transition after birth. We performed a secondary outcome analysis of a prospective observational study in preterm and term neonates. Ten and 15 min after birth, arterial blood pressure and heart rate were assessed, and CO-bioimpedance was measured using electrical bioimpedance method (Aesculon monitor, Osypka, Germany). We calculated COest/adj LaZ and compared it to CO-bioimpedance. Further, we performed a correlation analysis. Thirty-two neonates with a median (IQR) gestational age of 37.0 (32.0–39.4) weeks were included. Mean ± SD CO-bioimpedance was 0.62 ± 0.15 l/min, and COest/adj LaZ was calculated to be 0.64 ± 0.10 l/min, whereby both correlated significantly (p = 0.025, r = 0.359) with each other. Conclusion: The present study demonstrates high comparability of COest/adj LaZ and CO-bioimpedance in neonates during immediate transition after birth, suggesting that cardiac output can be derived in a cost-effective and feasible manner if other methods are not available.What is Known:• Echocardiography is considered the gold standard for non-invasive CO evaluation, but its feasibility during the immediate transition period is limited.What is New:• Non-invasive methods such as CO-bioimpedance for cardiac output (CO) measurement and the Liljestrand and Zander (LaZ) formula for estimating CO offer promising alternatives during the immediate transition period.

CARDIAC OUTPUT ESTIMATION: PULSE WAVE ANALYSIS (ANTARES) HIGHLY CORRELATES TO ECHOCARDIOGRAPHY ASSESSMENT

Objective: Evaluation of cardiac output (CO) is crucial for understanding cardiac function and diagnosis of heart failure. While invasive thermodilution procedures serve as the gold standard for CO assessment, routine clinical practice has widely adopted transthoracic Doppler echocardiography (TTE) as the established non-invasive method. Nevertheless, there is a persistent demand for alternative non-invasive approaches, aiming to improve the efficiency of CO estimation, mitigate complications associated with invasive methods, and extend its application to non-intensive care settings, all of which potentially can be offered by oscillometric pulse wave analysis (PWA). This study aims to compare the non-invasive estimation of CO using TTE and the oscillometric PWA algorithm Antares. Design and method: We compared non-invasive cardiac output data obtained through two-dimensional transthoracic echocardiography with data obtained from an oscillometric blood pressure device (custo med GmbH, Ottobrunn, Germany) utilizing the integrated Antares algorithm (Redwave Medical GmbH, Jena, Germany). A total of 59 patients, undergoing elective cardiac catheterization for clinical reasons, were included in the study (mean age 71±10 years, 24% females), but only echocardiography-data with CO were used for analysis. Agreement between the two CO measurement methods (TTE versus Antares) was evaluated through Bland-Altman analysis, Student's t-test, and Pearson correlations. Results: The mean difference in CO was 0.04 ± 1.03 l/min. No statistically significant difference in means was observed between the two CO measurement methods. Significant correlations between transthoracic echocardiography (TTE) and Antares CO were evident in the overall population (r=0.71), as well as in both, female (r=0.80) and male patients (r=0.67; all p&lt;0.001). Conclusions: The oscillometric PWA algorithm Antares and the established TTE exhibit strong correlations for non-invasive CO estimation in both male and female patients, with no statistically significant differences between the two approaches. This study opens the door to a valid and simple detection of heart failure that is seamlessly integrated into a quick and easy-to-perform upper arm blood pressure measurement.

Value of carotid corrected flow time or changes value of FTc could be more useful in predicting fluid responsiveness in patients undergoing robot-assisted gynecologic surgery: a prospective observational study.

The aim of this study was to evaluate the ability of point-of-care Doppler ultrasound measurements of carotid corrected flow time and its changes induced by volume expansion to predict fluid responsiveness in patients undergoing robot-assisted gynecological surgery. In this prospective study, carotid corrected flow time was measured using Doppler images of the common carotid artery before and after volume expansion. The stroke volume index at each time point was recorded using noninvasive cardiac output monitoring with MostCare. Of the 52 patients enrolled, 26 responded. The areas under the receiver operating characteristic curves of the carotid corrected flow time and changes in carotid corrected flow time induced by volume expansion were 0.82 and 0.67, respectively. Their optimal cut-off values were 357 and 19.5 ms, respectively. Carotid corrected flow time was superior to changes in carotid corrected flow time induced by volume expansion for predicting fluid responsiveness in this population.

Electrical cardiometry assessment of cardiac output compared to echocardiography in septic shock patients

Background Cardiac output (CO) measurement is essential for guiding therapeutic decisions in critically ill patients. Electrical cardiometry (EC), which is based on thoracic electrical bioimpedance, can measure CO in a continuous and noninvasive way. The benefits of EC are continuous monitoring, low time consumption, portability, and user independence. Transthoracic echocardiography has been a noninvasive method to assess CO despite being noncontiguous and operator dependent. Aim This study aimed to compare EC and echocardiography (Echo) in measuring CO in septic shock patients and assess the reliability and accuracy of EC for noninvasive CO monitoring. Patients and methods Fifty adult patients were admitted to the Critical Care Medicine Department, diagnosed with septic shock according to the surviving sepsis campaign, and fulfilling the inclusion and exclusion criteria from January 2023 to October 2023, and they were subjected to EC, Echo, and ECG recording. Results There was a strong positive significant correlation between CO measurements by echo and EC (r=0.988, P&lt;0.001), and there was a strong positive significant correlation between stroke volume (SV) measurements by echo and EC (r=0.999, P&lt;0.001). Also, there was a strong positive significant correlation between SV and CO measured by both techniques (r=0.782, P&lt;0.001) (r=0.790, P&lt;0.001, respectively). Conclusion Compared to Echo, EC can be used as a continuous, noninvasive method for monitoring CO and SV, as it provides accurate and reliable measurements.

Noninvasive Cardiac Output Monitoring by Electrical Cardiometry with Transthoracic Echocardiography in Postoperative Paediatric Cardiac Surgical Patients: Comment.

Noninvasive Cardiac Output Monitoring by Electrical Cardiometry with Transthoracic Echocardiography in Postoperative Paediatric Cardiac Surgical Patients: Comment.

Monitoring CO2 kinetics as a marker of cardiopulmonary efficiency.

To describe current and near future developments and applications of CO2 kinetics in clinical respiratory and cardiovascular monitoring. In the last years, we have witnessed a renewed interest in CO2 kinetics in relation with a better understanding of volumetric capnography and its derived parameters. This together with technological advances and improved measurement systems have expanded the monitoring potential of CO2 kinetics including breath by breath continuous end-expiratory lung volume and continuous noninvasive cardiac output. Dead space has slowly been gaining relevance in clinical monitoring and prognostic evaluation. Easy to measure dead space surrogates such as the ventilatory ratio have demonstrated a strong prognostic value in patients with acute respiratory failure. The kinetics of carbon dioxide describe many relevant physiological processes. The clinical introduction of new ways of assessing respiratory and circulatory efficiency based on advanced analysis of CO2 kinetics are paving the road to a long-desired goal in clinical monitoring of critically ill patients: the integration of respiratory and circulatory monitoring during mechanical ventilation.

A comparative study between serum lactate level versus change in end tidal carbon dioxide level regarding assessment of hemodynamic instability in intensive care unit patients after cardiac surgeries

ABSTRACT Background After cardiac surgeries, elevated lactate level is used as a marker of tissue hypoperfusion. Still, there is a search for other helpful markers of hemodynamic instability. Exhaled carbon dioxide has been recently studied as marker of cardiac output and tissue perfusion and may be considered a reliable alternative which is more convenient and real time. Objectives The main aim is to correlate between end tidal carbon dioxide (ETCO2) and serum lactate level as indicators of hemodynamic instability in intensive care unit (ICU) patients after cardiac surgeries. The secondary objective is to correlate the measured parameters to the changes in the vital data and the resuscitation efforts. Methods A prospective cohort study that enrolled 51 adult patients admitted to ICU after cardiac surgeries. The serum lactate and ETCO2 values as well as vital data and vasopressor doses were recorded on admission to ICU, after 2 hours and after 6 hours. Results The study shows insignificant weak positive correlation between Lactate and ETCO2 levels at admission (r = 0.172, p value = 0.229), and insignificant negative weak correlation after 2 hours (r = -0.148, p value = 0.300) and after 6 hours (r = -0.235, p value = 0.096). Moreover, lactate level showed significant direct relation with the doses of vasopressors at admission, after 2 hours and after 6 hours postoperative (p value < 0.001 at all intervals). Whereas there was insignificant relation between ETCO2 and doses of vasopressors at all intervals (p value = 0.23, 0.4 and 0.18 respectively). Conclusion In post-cardiac surgery ICU patients we detected no statistically significant relation between serum lactate and ETCO2 as indicators of hemodynamic instability. The change in ETCO2 over a period of time has failed so far to be of a beneficial value as a non-invasive real-time cardiac output monitoring parameter. In addition, serum lactate had strong correlation with changes in vital signs and resuscitation efforts.

Use of the USCOM® noninvasive cardiac output measurement system to predict the development of pre-eclampsia in hypertensive pregnancies

ABSTRACT Objectives To assess the ability of the USCOM® (USCOM), using measurements of cardiac output (CO) and systemic vascular resistance (SVR), to predict the development of pre-eclampsia (PE) and severe PE in hypertensive pregnancies. Study design Prospective cohort study of women in the second or third trimester recruited at a tertiary center in Sydney, Australia. Demographic data and hemodynamic measurements using the USCOM were taken for all study participants at recruitment. Pregnancy outcome, including development of PE and severe PE, was tracked. Data were analyzed using ANOVA testing, pair-wise comparison testing, and Student’s t-testing. Results Recruitment included 65 normotensive controls, 34 women with chronic hypertension (CH), 51 with gestational hypertension (GH), and 21 with PE. Significantly higher weight, body surface area, and blood pressure measurements were found in the hypertensive, compared with the normotensive control and pregnancies. There were no observed differences in USCOM-measured CO, cardiac index, SVR, or systemic vascular resistance index between hypertensive women who did versus did not develop PE or severe PE in later pregnancy. Analysis of the CH and GH subgroups, as well as only unmedicated hypertensive women (n = 24), also showed no significant difference in hemodynamic parameters between those who did or did not develop PE or severe PE. Conclusions Our group was unable to successfully predict the onset of PE or severe PE based on hemodynamic parameters measured with the USCOM. It is possible this relates to the high proportion of women on antihypertensive medication at recruitment.

Validation of a noninvasive cardiac output monitor in maternal cardiac disease: comparison of NICOM and transthoracic echocardiogram

The physiological changes to the cardiovascular system during pregnancy are considerable and are more pronounced in those with cardiac disease. In the general population, noninvasive hemodynamic monitoring is a valid alternative to pulmonary artery catheterization, which poses risk in the pregnant population. There is limited data on noninvasive cardiac output monitoring in pregnancy as an alternative to pulmonary artery catheterization. We sought to compare transthoracic echocardiography with a noninvasive cardiac output monitor (NICOM, Cheetah Medical) in pregnant patients with and without cardiac disease. This was a prospective, open-label validation study that compared 2-dimensional transthoracic echocardiography with NICOM estimations of cardiac output in each trimester of pregnancy and the postpartum period. Participants with and without cardiac disease with a singleton gestation were included. NICOM estimations of cardiac output were derived from thoracic bioreactance and compared with 2-dimensional transthoracic echocardiography for both precision and accuracy. A mean percentage difference of ±30% between the 2 devices was considered acceptable agreement between the 2 measurement techniques. A total of 58 subjects were enrolled; 36 did not have cardiac disease and 22 had cardiac disease. Heart rate measurements between the 2 devices were strongly correlated in both groups, whereas stroke volume and cardiac output measurements showed weak correlation. When comparing the techniques, the NICOM device overestimated cardiac output in the control group in all trimesters and the postpartum period (mean percentage differences were 50.3%, 52.7%, 48.1%, and 51.0% in the first, second, and third trimesters and the postpartum period, respectively). In the group with cardiac disease, the mean percentage differences were 31.9%, 29.7%, 19.6%, and 35.2% for the respective timepoints. The NICOM device consistently overestimated cardiac output when compared with 2-dimensional transthoracic echocardiography at all timepoints in the control group and in the first trimester and postpartum period for the cardiovascular disease group. The physiological changes of pregnancy, specifically the mean chest circumference and total body water, may alter the accuracy of the cardiac output measurement by the NICOM device as they are currently estimated. Although NICOM has been validated for use in the critical care setting, there is insufficient data to support its use in pregnancy.

Comparison of noninvasive cardiac output and stroke volume measurements using electrical impedance tomography with invasive methods in a swine model.

Pulmonary artery catheterization (PAC) has been used as a clinical standard for cardiac output (CO) measurements on humans. On animals, however, an ultrasonic flow sensor (UFS) placed around the ascending aorta or pulmonary artery can measure CO and stroke volume (SV) more accurately. The objective of this paper is to compare CO and SV measurements using a noninvasive electrical impedance tomography (EIT) device and three invasive devices using UFS, PAC-CCO (continuous CO) and arterial pressure-based CO (APCO). Thirty-two pigs were anesthetized and mechanically ventilated. A UFS was placed around the pulmonary artery through thoracotomy in 11 of them, while the EIT, PAC-CCO and APCO devices were used on all of them. Afterload and contractility were changed pharmacologically, while preload was changed through bleeding and injection of fluid or blood. Twenty-three pigs completed the experiment. Among 23, the UFS was used on 7 pigs around the pulmonary artery. The percentage error (PE) between COUFS and COEIT was 26.1%, and the 10-min concordance was 92.5%. Between SVUFS and SVEIT, the PE was 24.8%, and the 10-min concordance was 94.2%. On analyzing the data from all 23 pigs, the PE between time-delay-adjusted COPAC-CCO and COEIT was 34.6%, and the 10-min concordance was 81.1%. Our results suggest that the performance of the EIT device in measuring dynamic changes of CO and SV on mechanically-ventilated pigs under different cardiac preload, afterload and contractility conditions is at least comparable to that of the PAC-CCO device. Clinical studies are needed to evaluate the utility of the EIT device as a noninvasive hemodynamic monitoring tool.

Cardiac output estimation using ballistocardiography: a feasibility study in healthy subjects

There is no reliable automated non-invasive solution for monitoring circulation and guiding treatment in prehospital emergency medicine. Cardiac output (CO) monitoring might provide a solution, but CO monitors are not feasible/practical in the prehospital setting. Non-invasive ballistocardiography (BCG) measures heart contractility and tracks CO changes. This study analyzed the feasibility of estimating CO using morphological features extracted from BCG signals. In 20 healthy subjects ECG, carotid/abdominal BCG, and invasive arterial blood pressure based CO were recorded. BCG signals were adaptively processed to isolate the circulatory component from carotid (CCc) and abdominal (CCa) BCG. Then, 66 features were computed on a beat-to-beat basis to characterize amplitude/duration/area/length of the fluctuation in CCc and CCa. Subjects’ data were split into development set (75%) to select the best feature subset with which to build a machine learning model to estimate CO and validation set (25%) to evaluate model’s performance. The model showed a mean absolute error, percentage error and 95% limits of agreement of 0.83 L/min, 30.2% and − 2.18–1.89 L/min respectively in the validation set. BCG showed potential to reliably estimate/track CO. This method is a promising first step towards an automated, non-invasive and reliable CO estimator that may be tested in prehospital emergencies.

Evolving trends in the surgical, anaesthetic, and intensive care management of acute spinal cord injuries in the UK.

We surveyed the treatment of acute spinal cord injuries in the UK and compared current practices with 10 years ago. A questionnaire survey was conducted amongst neurosurgeons, neuroanaesthetists, and neurointensivists that manage patients with acute spinal cord injuries. The survey gave two scenarios (complete and incomplete cervical spinal cord injuries). We obtained opinions on the speed of transfer, timing and aim of surgery, choice of anaesthetic, intraoperative monitoring, targets for physiological parameters, and drug treatments. We received responses from 78.6% of UK units that manage acute spinal cord injuries (33 neurosurgeons, 56 neuroanaesthetists/neurointensivists). Most neurosurgeons operate within 12h for incomplete (82%) and complete (64%) injuries. There is a significant shift from 10 years ago, when only 61% (incomplete) and 30% (complete) of neurosurgeons operated within 12h. The preferred anaesthetic technique in 2022 is total intravenous anaesthesia (TIVA), used by 69% of neuroanaesthetists. Significantly more intraoperative monitoring is now used at least sometimes, including bispectral index (91%), non-invasive cardiac output (62%), and neurophysiology (73-77%). Methylprednisolone is no longer used by surgeons. Achieving at least 80mmHg mean arterial blood pressure is recommended by 70% neurosurgeons, 62% neuroanaesthetists, and 75% neurointensivists. Between 2012 and 2022, there was a paradigm shift in managing acute spinal cord injuries in the UK with earlier surgery and more intraoperative monitoring. Variability in practice persists due to lack of high-quality evidence and consensus guidelines.