Evaluation of a noninvasive cardiac output monitor in mechanically ventilated children

Novel approaches to capturing and using continuous cardiorespiratory physiological data in hospitalized children

Continuous cardiorespiratory physiological monitoring is a cornerstone of care in hospitalized children. The data generated by monitoring devices coupled with machine learning could transform the way we provide care. This scoping review summarizes existing evidence on novel approaches to continuous cardiorespiratory monitoring in hospitalized children. We aimed to identify opportunities for the development of monitoring technology and the use of machine learning to analyze continuous physiological data to improve the outcomes of hospitalized children. We included original research articles published on or after January 1, 2001, involving novel approaches to collect and use continuous cardiorespiratory physiological data in hospitalized children. OVID Medline, PubMed, and Embase databases were searched. We screened 2909 articles and performed full-text extraction of 105 articles. We identified 58 articles describing novel devices or approaches, which were generally small and single-center. In addition, we identified 47 articles that described the use of continuous physiological data in prediction models, but only 7 integrated multidimensional data (e.g., demographics, laboratory results). We identified three areas for development: (1) further validation of promising novel devices; (2) more studies of models integrating multidimensional data with continuous cardiorespiratory data; and (3) further dissemination, implementation, and validation of prediction models using continuous cardiorespiratory data. IMPACT: We performed a comprehensive scoping review of novel approaches to capture and use continuous cardiorespiratory physiological data for monitoring, diagnosis, providing care, and predicting events in hospitalized infants and children, from novel devices to machine learning-based prediction models. We identified three key areas for future development: (1) further validation of promising novel devices; (2) more studies of models integrating multidimensional data with continuous cardiorespiratory data; and (3) further dissemination, implementation, and validation of prediction models using cardiorespiratory data.

Capnodynamics - noninvasive cardiac output and mixed venous oxygen saturation monitoring in children

Hemodynamic monitoring in children is challenging for many reasons. Technical limitations in combination with insufficient validation against reference methods, makes reliable monitoring systems difficult to establish. Since recent studies have highlighted perioperative cardiovascular stability as an important factor for patient outcome in pediatrics, the need for accurate hemodynamic monitoring methods in children is obvious. The development of mathematical processing of fast response mainstream capnography signals, has allowed for the development of capnodynamic hemodynamic monitoring. By inducing small changes in ventilation in intubated and mechanically ventilated patients, fluctuations in alveolar carbon dioxide are created. The subsequent changes in carbon dioxide elimination can be used to calculate the blood flow participating in gas exchange, i.e., effective pulmonary blood flow which equals the non-shunted pulmonary blood flow. Cardiac output can then be estimated and continuously monitored in a breath-by-breath fashion without the need for additional equipment, training, or calibration. In addition, the method allows for mixed venous oxygen saturation (SvO₂) monitoring, without pulmonary artery catheterization. The current review will discuss the capnodyamic method and its application and limitation as well as future potential development and functions in pediatric patients.

Volumetric Capnography in Pediatric Extracorporeal Membrane Oxygenation: A Case Series

The kinetics of carbon dioxide elimination (VCO2) may be used as a surrogate for pulmonary blood flow. As such, we can apply a novel use of volumetric capnography to assess hemodynamic stability in patients requiring extracorporeal membrane oxygenation (ECMO). We report our experience of pediatric patients requiring ECMO support who were monitored using volumetric capnography. We describe the use of VCO2 and its association with successful decannulation. This is a prospective observational study of pediatric patients requiring ECMO support at The Children's Hospital at Montefiore from 2017 to 2019. A Respironics NM3 monitor was applied to each patient. Demographics, hemodynamic data, blood gases, and VCO2 (mL/min) data were collected. Data were collected immediately prior to and after decannulation. Over the course of the study period, seven patients were included. Predecannulation VCO2 was higher among patients who were successfully decannulated than nonsurvivors (109 [35, 230] vs. 12.4 [7.6, 17.2] mL/min), though not statistically significant. Four patients (57%) survived without further mechanical support; two (29%) died, and one (14%) was decannulated to Berlin. Predecannulation VCO2 appears to correlate with hemodynamic stability following decannulation. This case series adds to the growing literature describing the use of volumetric capnography in critical care medicine, particularly pediatric patients requiring ECMO. Prospective studies are needed to further elucidate the use of volumetric capnography and optimal timing for ECMO decannulation.

Intensive care management of right ventricular failure and pulmonary hypertension crises

Pulmonary hypertension (PH), an often unrelenting disease that carries with it significant morbidity and mortality, affects not only the pulmonary vasculature but, in turn, the right ventricle as well. The survival of patients with PH is closely related to the right ventricular function. Therefore, having an understanding of how to manage right ventricular failure (RVF) and acute pulmonary hypertensive crises is imperative for clinicians who encounter these patients. This review addresses the management of these patients in detail, addressing: (a) the pathophysiology of RVF, (b) intensive care monitoring of these patients in the intensive care unit, (c) imaging of the right ventricle, (d) intubation and mechanical ventilation, (e) inotrope and vasopressor selection, (f) pulmonary vasodilator use, (g) interventional and surgical procedures for the acutely failing right ventricle, and (h) mechanical support for RVF.

Volumetric Capnography Monitoring and Effects of Epinephrine on Volume of Carbon Dioxide Elimination during Resuscitation after Cardiac Arrest in a Swine Pediatric Ventricular Fibrillatory Arrest

The aim of this study was to examine the use of volumetric capnography monitoring to assess cardiopulmonary resuscitation (CPR) effectiveness by correlating it with cardiac output (CO), and to evaluate the effect of epinephrine boluses on both end-tidal carbon dioxide (EtCO 2 ) and the volume of CO 2 elimination (VCO 2 ) in a swine ventricular fibrillation cardiac arrest model. Planned secondary analysis of data collected to investigate the use of noninvasive monitors in a pediatric swine ventricular fibrillation cardiac arrest model was performed. Twenty-eight ventricular fibrillatory arrests with open cardiac massage were conducted. During CPR, EtCO 2 and VCO 2 had strong correlation with CO, measured as a percentage of baseline pulmonary blood flow, with correlation coefficients of 0.83 ( p  < 0.001) and 0.53 ( p  = 0.018), respectively. However, both EtCO 2 and VCO 2 had weak and nonsignificant correlation with diastolic blood pressure during CPR 0.30 ( p  = 0.484) (95% confidence interval [CI], -0.51-0.83) and 0.25 ( p  = 0.566) (95% CI, -0.55-0.81), respectively. EtCO 2 and VCO 2 increased significantly after the first epinephrine bolus without significant change in CO. The correlations between EtCO 2 and VCO 2 and CO were weak 0.20 ( p  = 0.646) (95% CI, -0.59-0.79), and 0.27 ( p  = 0.543) (95% CI, -0.54-0.82) following epinephrine boluses. Continuous EtCO 2 and VCO 2 monitoring are potentially useful metrics to ensure effective CPR. However, transient epinephrine administration by boluses might confound the use of EtCO 2 and VCO 2 to guide chest compression.

Correlation between Regional Cerebral Saturation and Invasive Cardiac Index Monitoring after Heart Transplantation Surgery

The present study assessed the correlations between cerebral regional saturation detected by near infrared spectroscopy (NIRS) and cardiac index (CI) measured by pulmonary artery catheter. This was a retrospective cohort study conducted in the cardiac intensive care unit in a tertiary care children's hospital. Patients younger than 18 years of age who underwent heart transplantation and had a pulmonary artery catheter on admission to the pediatric cardiac intensive care unit between January, 2010, and August, 2013, were included. There were no interventions. A total of 10 patients were included with median age of 14 years (range, 7-17). Indications for transplantation were dilated cardiomyopathy ( n  = 9) and restrictive cardiomyopathy ( n  = 1). Mixed venous oxygen saturation (SvO 2 ), cerebral regional tissue saturation (rSO 2 ), and CI were recorded hourly for 8 to 92 hours post-transplantation. Spearman's rank correlation coefficient was used to assess correlations between SvO 2 and cerebral rSO 2 and between CI and cerebral rSO 2 . A total of 410 data points were collected. Median, 25th and 75th percentiles of cerebral rSO 2 , CI, and SvO 2 were 65% (54-69), 2.9 L/min/m 2 (2.2-4.0), and 75% (69-79), respectively. The correlation coefficient between cerebral rSO 2 and CI was 0.104 ( p  = 0.034) and that for cerebral rSO 2 and SvO 2 was 0.11 ( p  = 0.029). The correlations between cerebral rSO 2 and CI and between cerebral rSO 2 and SvO 2 were weak. Cerebral rSO 2 as detected by NIRS may not be an accurate indicator of CI in critically ill patients.

Correlation between minute carbon dioxide elimination and pulmonary blood flow in single-ventricle patients after stage 1 palliation and 2-ventricle patients with intracardiac shunts: A pilot study

BACKGROUND

Assessment of pulmonary blood flow and cardiac output is critical in the postoperative management of patients with single-ventricle physiology or 2-ventricle physiology with intracardiac shunting. Currently, such hemodynamic data are only obtainable by invasive procedures, such as cardiac catheterization or the use of a pulmonary artery catheter. Ready availability of such information, especially if attainable noninvasively, could be a valuable addition to postoperative management.

AIMS

The aim of this study was to assess the correlation between volume of CO₂ elimination obtained by volumetric capnography and pulmonary blood flow in pediatric patients with single-ventricle physiology after stage 1 palliation as well as in patients with other cardiac lesions associated with intracardiac shunting.

METHODS

This prospective cohort study included children with congenital or acquired heart disease who underwent cardiac catheterization as part of clinical care. Cardiac output, pulmonary blood flow, and volume of CO₂ elimination were simultaneously collected. Spearman's rank correlation coefficients were used to assess correlation between measurements after controlling for minute ventilation.

RESULTS

Thirty-five patients were enrolled and divided into 3 groups. Group 1 (n = 8) included single-ventricle patients after stage 1 palliation. Group 2 (n = 10) patients had structural heart disease with 2 ventricles and intracardiac shunting. Group 3 (n = 17) had structurally normal hearts. Among Group 1 patients, the correlation coefficients (R² ) between volume of CO₂ elimination and pulmonary blood flow and volume of CO₂ elimination and cardiac output were 0.60 (P = .02) 95% CI [0.01-0.79] and 0.29 (P = .74) 95% CI [-0.91 - 0.86], respectively. In patients with 2 ventricles associated with intracardiac shunts (Group 2), the correlation coefficients between volume of CO₂ elimination and pulmonary blood flow and volume of CO₂ elimination and cardiac output were 0.86 (P = .001) 95% CI [0.53 - 0.97] and 0.73 (P = .001) 95% CI [0.29 - 0.95], respectively. Among Group 3 patients, the correlation coefficient between volume of CO₂ elimination and pulmonary blood flow was 0.66 (P = .038) 95% CI [0.29 - 0.87].

CONCLUSION

Volume of CO₂ elimination may be a surrogate marker of pulmonary blood flow in single-ventricle patients and patients with biventricular physiology with intracardiac shunting. Also, among patients with normal cardiac anatomy, volume of CO₂ elimination may be a marker of cardiac output.

Comparison of three non-invasive hemodynamic monitoring methods in critically ill children

Introduction

Hemodynamic parameters measurements were widely conducted using pulmonary artery catheter (PAC) with thermodilution as a reference standard. Due to its technical difficulties in children, transthoracic echocardiography (TTE) has been widely employed instead. Nonetheless, TTE requires expertise and is time-consuming. Noninvasive cardiac output monitoring such as ultrasonic cardiac output monitor (USCOM) and electrical velocimetry (EV) can be performed rapidly with less expertise requirement. Presently, there are inconsistent evidences, variable precision, and reproducibility of EV, USCOM and TTE measurements. Our objective was to compare USCOM, EV and TTE in hemodynamic measurements in critically ill children.

Materials and methods

This was a single center, prospective observational study in critically ill children. Children with congenital heart diseases and unstable hemodynamics were excluded. Simultaneous measurements of hemodynamic parameters were conducted using USCOM, EV, and TTE. Inter-rater reliability was determined. Bland-Altman plots were used to analyse agreement of assessed parameters.

Results

Analysis was performed in 121 patients with mean age of 4.9 years old and 56.2% of male population. Interrater reliability showed acceptable agreement in all measured parameters (stroke volume (SV), cardiac output (CO), velocity time integral (VTI), inotropy (INO), flow time corrected (FTC), aortic valve diameter (AV), systemic vascular resistance (SVR), and stroke volume variation (SVV); (Cronbach’s alpha 0.76–0.98). Percentages of error in all parameters were acceptable by Bland-Altman analysis (9.2–28.8%) except SVR (30.8%) and SVV (257.1%).

Conclusion

Three noninvasive methods might be used interchangeably in pediatric critical care settings with stable hemodynamics. Interpretation of SVV and SVR measurements must be done with prudence.

Accuracy and precision of minimally-invasive cardiac output monitoring in children: a systematic review and meta-analysis

Several minimally-invasive technologies are available for cardiac output (CO) measurement in children, but the accuracy and precision of these devices have not yet been evaluated in a systematic review and meta-analysis. We conducted a comprehensive search of the medical literature in PubMed, Cochrane Library of Clinical Trials, Scopus, and Web of Science from its inception to June 2014 assessing the accuracy and precision of all minimally-invasive CO monitoring systems used in children when compared with CO monitoring reference methods. Pooled mean bias, standard deviation, and mean percentage error of included studies were calculated using a random-effects model. The inter-study heterogeneity was also assessed using an I(2) statistic. A total of 20 studies (624 patients) were included. The overall random-effects pooled bias, and mean percentage error were 0.13 ± 0.44 l min(-1) and 29.1 %, respectively. Significant inter-study heterogeneity was detected (P < 0.0001, I(2) = 98.3 %). In the sub-analysis regarding the device, electrical cardiometry showed the smallest bias (-0.03 l min(-1)) and lowest percentage error (23.6 %). Significant residual heterogeneity remained after conducting sensitivity and subgroup analyses based on the various study characteristics. By meta-regression analysis, we found no independent effects of study characteristics on weighted mean difference between reference and tested methods. Although the pooled bias was small, the mean pooled percentage error was in the gray zone of clinical applicability. In the sub-group analysis, electrical cardiometry was the device that provided the most accurate measurement. However, a high heterogeneity between studies was found, likely due to a wide range of study characteristics.

Continuous noninvasive cardiac output in children: is this the next generation of operating room monitors? Initial experience in 402 pediatric patients

BACKGROUND

Electrical Cardiometry(™) (EC) estimates cardiac parameters by measuring changes in thoracic electrical bioimpedance during the cardiac cycle. The ICON(®), using four electrocardiogram electrodes (EKG), estimates the maximum rate of change of impedance to peak aortic blood acceleration (based on the premise that red blood cells change from random orientation during diastole (high impedance) to an aligned state during systole (low impedance)).

OBJECTIVE

To determine whether continuous cardiac output (CO) data provide additional information to current anesthesia monitors that is useful to practitioners.

METHODS

After IRB approval and verbal consent, 402 children were enrolled. Data were uploaded to our anesthesia record at one-minute intervals. Ten-second measurements (averaged over the previous 20 heart beats) were downloaded to separate files for later comparison with routine OR monitors.

RESULTS

Data from 374 were in the final cohort (loss of signal or improper lead placement); 292,012 measurements during 58,049 min of anesthesia were made in these children (1 day to 19 years and 1 to 107 kg). Four events had a ≥25% reduction in cardiac index at least 1 min before a clinically important change in other monitored parameters; 18 events in 14 children confirmed manifestations of other hemodynamic measures; eight events may have represented artifacts because the observed measurements did not seem to fit the clinical parameters of the other monitors; three other events documented decreased stroke index with extreme tachycardia.

CONCLUSIONS

Electrical cardiometry provides real-time cardiovascular information regarding developing hemodynamic events and successfully tracked the rapid response to interventions in children of all sizes. Intervention decisions must be based on the combined data from all monitors and the clinical situation. Our experience suggests that this type of monitor may be an important addition to real-time hemodynamic monitoring.

Non invasive monitoring in mechanically ventilated pediatric patients

Cardiopulmonary monitoring is a key component in the evaluation and management of critically ill patients. Clinicians typically rely on a combination of invasive and non-invasive monitoring to assess cardiac output and adequacy of ventilation. Recent technological advances have led to the introduction: of continuous non-invasive monitors that allow for data to be obtained at the bedside of critically ill patients. These advances help to identify hemodynamic changes and allow for interventions before complications occur. In this manuscript, we highlight several important methods of non-invasive cardiopulmonary monitoring, including capnography, transcutaneous monitoring, pulse oximetry, and near infrared spectroscopy.

Neonatal hemodynamics: monitoring, data acquisition and analysis

Monitoring of cardiovascular function is critical to both clinical care and research as the use of sophisticated monitoring systems enable us to obtain accurate, reliable and real-time information on developmental hemodynamics in health and disease. Novel approaches to comprehensive hemodynamic monitoring and data acquisition will undoubtedly aid in developing a better understanding of developmental cardiovascular physiology in neonates. In addition, development and use of state-of-the-art, comprehensive hemodynamic monitoring systems enable the recognition of signs of cardiovascular compromise in its early stages, and provide information on the hemodynamic response to treatment in critically ill patients.

A history of pediatric anesthesia: a tale of pioneers and equipment

The history of pediatric anesthesia is fascinating in terms of how inventive anesthesiologists became over time to address the needs for advances in surgery. We have many pioneers and heroes. We hope you will enjoy this brief overview and that we have not left out any of the early contributors to our speciality. Obviously there is insufficient space to include everyone.

Emerging technologies

Hemodynamic monitoring in critically ill patients has been considered part of the standard of care in managing patients with shock and/or acute lung injury, but outcome benefit, particularly in pediatric patients, has been questioned. There is difficulty in validating the reliability of monitoring devices, especially since this validation requires comparison to the pulmonary artery catheter, which has its own problems as a measurement tool. Interpretation of the available evidence reveals advantages and disadvantages of the available hemodynamic monitoring devices.

Noninvasive monitoring cardiac output using partial CO(2) rebreathing

This article reviews use of partial carbon dioxide rebreathing devices to determine cardiac output and their application for hemodynamic monitoring in the ICU and operating room. The primary focus is on the NICO monitoring device. Compared with conventional cardiac output methods, these techniques are noninvasive, easily automated, and provide real-time and continuous cardiac output monitoring. The advantages and limitations of each technique are different discussed.

[What non invasive haemodynamic assessment in paediatric intensive care unit in 2009?]

The haemodynamic assessment of the patients is a daily activity in paediatric intensive care unit. It completes and is guided by the clinical examination. The will to develop the least invasive possible coverage of the patients is a constant concern. The haemodynamic monitoring, all the more if it is invasive, ceaselessly has to put in balance the profit and the risk of beginning this technique at a fragile patient. In the last three decades, numerous non-invasive haemodynamic tools were developed. The ideal one must be reliable, reproducible, with a time of fast, easily useful answer, with a total harmlessness, cheap and allowing a monitoring continues. Among all the existing tools (oesophageal Doppler ultrasound method, transthoracic echocardiography, NICO, thoracic impedancemetry, plethysmography, sublingual capnography), no one allies all these qualities. We can consider that the transthoracic echocardiography gets closer to most of these objectives. We shall blame it for its cost and for the fact that it is an intermittent monitoring but both in the diagnosis and in the survey, it has no equal among the non-invasive tools of haemodynamic assessment from part the quality and the quantity of the obtained information. The learning of the basic functions (contractility evaluation, cardiac output, cardiac and the vascular filling) useful for the start of a treatment is relatively well-to-do. We shall miss the absence of training in this tool in France in its paediatric and neonatal specificity within the university or interuniversity framework.

Continuous, non-invasive techniques to determine cardiac output in children after cardiac surgery: evaluation of transesophageal Doppler and electric velocimetry

BACKGROUND

Continuous and non-invasive measurement of cardiac output (CO) may contribute helpful information to the care and treatment of the critically ill pediatric patient. Different methods are available but their clinical verification is still a major problem.

AIM

Comparison of reliability and safety of two continuous non-invasive methods with transthoracic echocardiography (TTE) for CO measurement: electric velocimetry technique (EV, Aesculon) and transesophageal Doppler (TED, CardioQP). METHODS/MATERIAL: In 26 infants and children who had undergone corrective cardiac surgery at a median age of 3.5 (1-17) years CO and stroke volume (SV) were obtained by EV, TED and TTE. Each patient had five measurements on the first day after surgery, during mechanical ventilation and sedation.

RESULTS

Values for CO and SV from TED and EV correlated well with those of TTE (r = 0.85 and r = 0.88), but mean values were significantly lower than the values of TTE for TED (P = 0.02) and EV (P = 0.001). According to Bland-Altman analysis, bias was 0.36 l/min with a precision of 1.67 l/min for TED vs. TTE and 0.87 l/min (bias) with a precision of 3.26 l/min for EV vs. TTE. No severe adverse events were observed and the handling of both systems was easy in the sedated child.

CONCLUSIONS

In pediatric patients non-invasive measurement of CO and SV with TED and EV is useful for continuous monitoring after heart surgery. Both new methods seem to underestimate cardiac output in terms of absolute values. However, TED shows tolerable bias and precision and may be helpful for continuous CO monitoring in a deeply sedated and ventilated pediatric patient, e.g. in the operating room or intensive care unit.

Cardiac output measurement using a modified carbon dioxide Fick method: a validation study in ventilated lambs

Cardiac output can be measured using a modified carbon dioxide Fick (mCO2F) method. A validation study was performed comparing mCO2F method-derived cardiac output (Q(mCO2F)) with invasively measured pulmonary blood flow. In seven randomly bred ventilated newborn lambs, cardiac output was manipulated by creating hemorrhagic hypotension. When steady state was reached, Q(mCO2F) was measured. Gas analysis was performed in simultaneously obtained arterial and venous blood samples (right atrium [RA], superior vena cava [SVC], and inferior vena cava [IVC]). Carbon dioxide exchange and pulmonary blood flow was measured continuously using a CO2SMO Plus monitor and a pulmonary ultrasonic flow probe (Q), respectively. Mean bias, defined as Q(mCO2F) - Q(ufp), was small (respectively, -0.082 L.min, -0.085 Lx min(-1) and -0.183 Lxmin(-1) for venous sampling from RA, SVC, and IVC). The limits of agreement were -0.328 to 0.164 Lxmin(-1) (RA), -0.335 to 0.165 Lxmin(-1) (SVC), and 0.415 to 0.049 Lxmin(-1) (IVC). In conclusion, measurement of cardiac output with the mCO2F method is reliable and easily applicable in ventilated newborn lambs. For clinical use, the site of venous blood sampling is of minor importance.

Comparison of noninvasive cardiac output measured by use of partial carbon dioxide rebreathing or the lithium dilution method in anesthetized foals

OBJECTIVE

To compare cardiac output (CO) measured by use of the partial carbon dioxide rebreathing method (NICO) or lithium dilution method (LiDCO) in anesthetized foals.

SAMPLE POPULATION

Data reported in 2 other studies for 18 neonatal foals that weighed 32 to 61 kg.

PROCEDURES

Foals were anesthetized and instrumented to measure direct blood pressure, heart rate, arterial blood gases, end-tidal isoflurane and carbon dioxide concentrations, and CO. Various COs were achieved by administration of dobutamine, norepinephrine, vasopressin, phenylephrine, and isoflurane to allow comparisons between LiDCO and NICO methods. Measurements were obtained in duplicate or triplicate. We allowed 2 minutes between measurements for LiDCO and 3 minutes for NICO after achieving a stable hemodynamic plane for at least 10 to 15 minutes at each CO.

RESULTS

217 comparisons were made. Correlation (r = 0.77) was good between the 2 methods for all determinations. Mean +/- SD measurements of cardiac index for all comparisons with the LiDCO and NICO methods were 138 +/- 62 mL/kg/min (range, 40 to 381 mL/kg/min) and 154 +/- 55 mL/kg/min (range, 54 to 358 mL/kg/min), respectively. Mean difference (bias) between LiDCO and NICO measurements was -17.3 mL/kg/min with a precision (1.96 x SD) of 114 mL/kg/min (range, -131.3 to 96.7). Mean of the differences of LiDCO and NICO measurements was 4.37 + (0.87 x NICO value).

CONCLUSIONS AND CLINICAL RELEVANCE

The NICO method is a viable, noninvasive method for determination of CO in neonatal foals with normal respiratory function. It compares well with the more invasive LiDCO method.