Cross-comparison of cardiac output trending accuracy of LiDCO, PiCCO, FloTrac and pulmonary artery catheters

Estimation of Cardiac Output Under Veno-Venous Extracorporeal Membrane Oxygenation: Comparing Thermodilution Methods to 3D Echocardiography

Thermodilution methods to determine cardiac output (CO) may be affected by veno-venous extracorporeal membrane oxygenation (ECMO). We compared CO estimations by pulmonary arterial thermodilution using a pulmonary arterial catheter (COPAC), transpulmonary thermodilution (COTPTD), and three-dimensional echocardiography (3DEcho) (CO3DEcho) in 18 patients under veno-venous ECMO. Comparisons between CO3DEcho and COPAC, and COTPTD were performed using correlation statistics and Bland-Altman analysis. Blood flow on ECMO support ranged from 4.3 to 5.8 L/min (median 4.9 L/min). Cardiac output measured with three-dimensional echocardiography was 5.2 L/min (3.8/5.9), COPAC was 7.3 L/min (5.9/7.9), and COTPTD was 7.3 L/min (6/8.2) (median [25%/75% percentile]). Bland-Altman analysis of CO3DEcho and COPAC revealed a mean bias of -2.06 L/min, with limits of agreement from -4.16 to 0.04 L/min. Bland-Altman analysis of CO3DEcho and COTPTD revealed a mean bias of -2.22 L/min, with limits of agreement from -4.18 to -0.25 L/min. We found a negative mean bias and negative limits of agreement between CO3DEcho and COPAC/COTPTD. We concluded an influence on the estimation of CO by thermodilution under ECMO most likely due to loss of indicator resulting in an overestimation of CO. Clinicians should consider this when monitoring thermodilution-based CO under ECMO.

Perioperative estimations of oxygen consumption from LiDCO™plus-derived cardiac output and Ca-cvO2 difference: Relationship with measurements by indirect calorimetry in elderly patients undergoing major abdominal surgery

BACKGROUND

Feasible estimations of perioperative changes in oxygen consumption (VO2) could enable larger studies of its role in postoperative outcomes. Current methods, either by reverse Fick calculations using pulmonary artery catheterisation or metabolic by breathing gas analysis, are often deemed too invasive or technically requiring. In addition, reverse Fick calculations report generally lower values of oxygen consumption.

METHODS

We investigated the relationship between perioperative estimations of VO2 (EVO2), from LiDCO™plus-derived (LiDCO Ltd, Cambridge, UK) cardiac output and arterial-central venous oxygen content difference (Ca-cvO2), with indirect calorimetry (GVO2) by QuarkRMR (COSMED srl. Italy), using data collected 2017-2018 during a prospective observational study on perioperative oxygen transport in 20 patients >65 years during epidural and general anaesthesia for open pancreatic or liver resection surgery. Eighty-five simultaneous intra- and postoperative measurements at different perioperative stages were analysed for prediction, parallelity and by traditional agreement assessment.

RESULTS

Unadjusted bias between GVO2 and EVO2 indexed for body surface area was 26 (95% CI 20 to 32) with limits of agreement (1.96SD) of -32 to 85 ml min-1m-2. Correlation adjusted for the bias was moderate, intraclass coefficient(A,1) 0.51(95% CI 0.34 to 0.65) [F (84,84) = 3.07, P<0.001]. There was an overall association between GVO2 and EVO2, in a random coefficient model [GVO2 = 73(95% CI 62 to 83) + 0.45(95% CI 0.29 to 0.61) EVO2 ml min-1m-2, P<0.0001]. GVO2 and EVO2 changed in parallel intra- and postoperatively when normalised to their respective overall means.

CONCLUSION

Based on this data, estimations from LiDCO™plus-derived cardiac output and Ca-cvO2 are not reliable as a surrogate for perioperative VO2. Results were in line with previous studies comparing Fick-based and metabolic measurements but limited by variability of data and possible underpowering. The parallelity at different perioperative stages and the prediction model can provide useful guidance and methodological tools for future studies on similar methods in larger samples.

Use of Transesophageal Echocardiography for Liver Transplantation: A Global Comparison of Practice From the ILTS, SATA, and LICAGE

BACKGROUND

Anesthesiologists frequently use intraoperative transesophageal echocardiography (TEE) to aid in the diagnosis and management of hemodynamic problems during liver transplantation (LT). Although the use of TEE in US centers continues to increase, data regarding international use are lacking.

METHODS

This prospective, global, survey-based study evaluates international experience with TEE for LT. Responses from 252 LT (105 US and 147 non-US) centers representing 1789 anesthesiologists were analyzed.

RESULTS

Routine use of TEE in the United States has increased in the last 5 y (from 37% to 47%), but only 21% of non-US LT anesthesiologists use TEE routinely. Lack of training (44% US versus 70% non-US) and equipment (9% non-US versus 34% US) were cited as obstacles. Most survey participants preferred not to perform a complete cardiac examination but rather use only 6 of 11 basic views. Although non-US LT anesthesiologists more frequently had additional clinical training than their US counterparts, they had less TEE experience (13% versus 44%) and less frequently, TEE certification (22% versus 35%). Most LT anesthesiologists agreed that TEE certification is essential for proficiency. Of all respondents, 89% agreed or strongly agreed that TEE provides valuable information needed for immediate clinical decision-making, and >86% agreed or strongly agreed that that information could not be derived from other sources.

CONCLUSIONS

The use of TEE for LT surgery in the US LT centers is currently higher compared with non-US LT centers. This may become a standard monitoring modality during LT in the near future.

Autonomous precision resuscitation during ground and air transport of an animal hemorrhagic shock model

We tested the ability of a physiologically driven minimally invasive closed-loop algorithm, called Resuscitation based on Functional Hemodynamic Monitoring (ReFit), to stabilize for up to 3 h a porcine model of noncompressible hemorrhage induced by severe liver injury and do so during both ground and air transport. Twelve animals were resuscitated using ReFit to drive fluid and vasopressor infusion to a mean arterial pressure (MAP) > 60 mmHg and heart rate < 110 min-1 30 min after MAP < 40 mmHg following liver injury. ReFit was initially validated in 8 animals in the laboratory, then in 4 animals during air (23nm and 35nm) and ground (9 mi) to air (9.5nm and 83m) transport returning to the laboratory. The ReFit algorithm kept all animals stable for ~ 3 h. Thus, ReFit algorithm can diagnose and treat ongoing hemorrhagic shock independent to the site of care or during transport. These results have implications for treatment of critically ill patients in remote, austere and contested environments and during transport to a higher level of care.

Complex Heart-Lung Ventilator Emergencies in the CICU

This review aims to enhance the comprehension and management of cardiopulmonary interactions in critically ill patients with cardiovascular disease undergoing mechanical ventilation. Highlighting the significance of maintaining a delicate balance, this article emphasizes the crucial role of adjusting ventilation parameters based on both invasive and noninvasive monitoring. It provides recommendations for the induction and liberation from mechanical ventilation. Special attention is given to the identification of auto-PEEP (positive end-expiratory pressure) and other situations that may impact hemodynamics and patients' outcomes.

Cardiac Output and Stroke Volume Assessments by Transthoracic Echocardiography and Pulse index Continuous Cardiac Output Monitor in Critically ill Adult Patients: A Comparative Study

PURPOSE

Bedside transthoracic echocardiography (TTEcho) is a noninvasive cardiac output (CO) monitoring method that has grown recently. However, there are questions regarding its accuracy compared to invasive methods. We aimed to evaluate the agreement and correlation of TTEcho and pulse index continuous CO (PiCCO) monitor measurements for CO and systolic volume (SV) in critically ill patients.

METHODS

This prospective experimental study included consecutive adult patients who required invasive hemodynamic monitoring admitted at an intensive care unit in the Federal District, Brazil, from January/2019 to January/2021. Correlation and agreement between SV and CO measurements by PiCCO and TTEcho were performed using the Spearman correlation and the Bland-Altman analysis.

RESULTS

The study enrolled 29 patients, with adequate TTEcho evaluations in all patients. There were very strong correlations between CO-TTEcho and CO-PiCCO (r = 0.845, P < .001) and SV-TTEcho and SV-PiCCO (r = 0.800, P < .001). TTEcho estimations for CO and SV were feasible within the limits of agreement in 96.6% (28/29) compared to PiCCO. The mean difference between CO-PiCCO and CO-TTEcho was 0.250 L/min (limits of agreement: -1.083 to 1.583 L/min, percentage error: 21.0%), and between SV-PiCCO and SV-TTEcho was 2.000 mL (limits of agreement: -16.960 to 20.960, percentage error: 24.3%). The reduced cardiac index (CI) measurements by TTEcho showed an accuracy of 89.7% (95% IC: 72.6%-97.8%) and an F1 score of 92.7% (95% IC: 75.0%-98.0%), considering the CI-PiCCO as the gold standard.

CONCLUSION

Echocardiographic measurements of CO and SV are comparable to measurements by PiCCO. These results reinforce echocardiography as a reliable tool to evaluate hemodynamics in critically ill patients.

A novel interpretative tool for early prediction of low cardiac output syndrome after valve surgery: online machine learning models

OBJECTIVE

Low cardiac output syndrome (LCOS) is a severe complication after valve surgery, with no uniform standard for early identification. We developed interpretative machine learning (ML) models for predicting LCOS risk preoperatively and 0.5 h postoperatively for intervention in advance.

METHODS

A total of 2218 patients undergoing valve surgery from June 2019 to Dec 2021 were finally enrolled to construct preoperative and postoperative models. Logistic regression, support vector machine (SVM), random forest classifier, extreme gradient boosting, and deep neural network were executed for model construction, and the performance of models was evaluated by area under the curve (AUC) of the receiver operating characteristic and calibration curves. Our models were interpreted through SHapley Additive exPlanations, and presented as an online tool to improve clinical operability.

RESULTS

The SVM algorithm was chosen for modeling due to better AUC and calibration capability. The AUCs of the preoperative and postoperative models were 0.786 (95% CI 0.729-0.843) and 0.863 (95% CI 0.824-0.902), and the Brier scores were 0.123 and 0.107. Our models have higher timeliness and interpretability, and wider coverage than the vasoactive-inotropic score, and the AUC of the postoperative model was significantly higher. Our preoperative and postoperative models are available online at http://njfh-yxb.com.cn:2022/lcos.

CONCLUSIONS

The first interpretable ML tool with two prediction periods for online early prediction of LCOS risk after valve surgery was successfully built in this study, in which the SVM model has the best performance, reserving enough time for early precise intervention in critical care.

Right Heart Failure in the Intensive Care Unit: Etiology, Pathogenesis, Diagnosis, and Treatment

Right heart (RH) failure carries a high rate of morbidity and mortality. Patients who present with RH failure often exhibit complex aberrant cardio-pulmonary physiology with varying presentations. The treatment of RH failure almost always requires care and management from an intensivist. Treatment options for RH failure patients continue to evolve rapidly with multiple options available, including different pharmacotherapies and mechanical circulatory support devices that target various components of the RH circulatory system. An understanding of the normal RH circulatory physiology, treatment, and support options for the RH failure patients is necessary for all intensivists to improve outcomes. The purpose of this review is to provide clinical guidance on the diagnosis and management of RH failure within the intensive care unit setting, and to highlight the different pathophysiological manifestations of RH failure, its hemodynamics, and treatment options available at the disposal of the intensivist.

Cardiovascular and Respiratory Effects of Increased Intra-Abdominal Pressure with and without Dexmedetomidine in Anesthetized Dogs

Intra-abdominal pressure (IAP) elevation during capnoperitoneum can cause adverse cardiovascular and respiratory effects. This study aimed to determine if a sequentially increased IAP affects cardiovascular and respiratory variables in anesthetized dogs and evaluate the effects of the constant-rate infusion of dexmedetomidine (Dex) on cardiovascular and respiratory variables with increased IAP. Five dogs were anesthetized and instrumented, and a Veress needle was equipped to adjust the IAP using a carbon dioxide insufflator. Stabilization was conducted for 1 h, and physiological variables were measured at IAPs of 0, 5, 10, 15, and 20 mmHg and after desufflation. After the washout period, the dogs underwent similar procedures along with a constant-rate infusion of dexmedetomidine. The cardiovascular effects of increased IAP up to 20 mmHg were not significant in healthy beagle dogs and those administered with dexmedetomidine. When comparing the control and dexmedetomidine groups, the overall significant effects of dexmedetomidine were noted on heart rate, cardiac output, and systemic vascular resistance during the experiment. Respiratory effects were not observed during abdominal insufflation when compared between different IAPs and between the two groups. Overall, an increased IAP of up to 20 mmHg did not significantly affect cardiovascular and respiratory variables in both the control and dexmedetomidine groups. This study suggests that the administration of a dexmedetomidine infusion is applicable in laparoscopic procedures in healthy dogs.

Pediatric Shock Review

Shock occurs when there is energy failure due to inadequate oxygen/glucose delivery to meet metabolic demands. Shock is a leading cause of death and disability in children worldwide. Types of shock include hypovolemic, cardiogenic, distributive, and obstructive. This review provides an overview of the epidemiology, pathophysiology, and clinical signs and symptoms of each of these types of shock, followed by a discussion of advancements in diagnostic tests and tools and management/treatment principles for different categories of shock.

Pulse contour techniques for perioperative hemodynamic monitoring: A nationwide carbon footprint and cost estimation

BACKGROUND

The question of environmentally sustainable perioperative medicine represents a new challenge in an era of cost constraints and climate crisis. The French Society of Anaesthesia and Intensive Care (SFAR) recommends stroke volume optimization in high-risk surgical patients. Pulse contour techniques have become increasingly popular for stroke volume monitoring during surgery. Some require the use of specific disposable pressure transducers (DPTs), whereas others can be used with standard DPTs.

OBJECTIVE

Quantify and compare the carbon footprint and cost of pulse contour techniques using specific and standard DPTs on a yearly basis and at a national level.

METHODS

We estimated the number of high-risk surgical patients monitored every year in France with a pulse contour technique, and the plastic waste, carbon footprint and cost associated with the use of specific and standard DPTs.

MAIN FINDINGS

When compared to pulse contour techniques working with a standard DPT, techniques requiring a specific DPT are responsible for an increase in carbon dioxide emission estimated at 65-83 tons/yr and for additional hospital cost estimated at €67 million/yr. If, as recommended by the SFAR, all high-risk surgical patients were monitored, the difference would reach 179-227 tons/yr for the environmental impact and €187 million/yr for the economic impact.

CONCLUSION

From an environmental and economic standpoint, pulse contour techniques working with standard DPTs should be recommended for the perioperative hemodynamic monitoring of high-risk surgical patients.

Comparison of cardiac index measurements in intensive care patients using continuous wave vs. pulsed wave echo-Doppler compared to pulse contour cardiac output

PURPOSE

Cardiac index (CI) assessments are commonly used in critical care to define shock aetiology and guide resuscitation. Echocardiographic assessment is non-invasive and has high levels of agreement with thermodilution assessment of CI. CI assessment is derived from the velocity time integral (VTI) assessed using pulsed wave (PW) doppler at the level of the left ventricular outflow tract divided by body mass index. Continuous wave (CW) doppler through the aortic valve offers an alternative means to assess VTI and may offer better assessment at high velocities.

METHODS

We performed a single centre, prospective, observational study in a 15-bed intensive care unit in a busy district general hospital. Patients had simultaneous measurements of cardiac index by Pulse Contour Cardiac Output (PiCCO) (thermodilution), transthoracic echocardiographic PW-VTI and CW-VTI. Mean differences were measured with Bland-Altman limits of agreement and percentage error (PE) calculations.

RESULTS

Data were collected on 52 patients. 71% were supported with noradrenaline with or without additional inotropic or vasopressor agents. Mean CIs were: CW-VTI 2.7 L/min/m² (range 0.78-5.11, SD 0.92). PW-VTI 2.33 L/min/m² (range 0.77-5.40, SD 0.90) and PiCCO 2.86 L/min/m² (range 1.50-5.56, SD 0.93). CW-VTI and PiCCO mean difference was - 0.16 L/min/m² PE 43.5%. PW-VTI and PiCCO had a mean difference of - 0.54 L/min/m² PE 38.6%. CW-VTI and PW-VTI had a mean difference of 0.38 L/min/m² PE 46.0%.

CONCLUSIONS

CI derived from both CW-VTI and PW-VTI methods underestimate CI compared to PiCCO, with the CW-VTI method having closer values overall to PiCCO. CW-VTI may offer a more accurate assessment of CI. If using Critchley's PE cutoff of 30%, none of the doppler methods may accurately reflect the actual cardiac index.

Prediction of Fluid Responsiveness Using Combined End-Expiratory and End-Inspiratory Occlusion Tests in Cardiac Surgical Patients

End-expiratory occlusion (EEO) and end-inspiratory occlusion (EIO) tests have been successfully used to predict fluid responsiveness in various settings using calibrated pulse contour analysis and echocardiography. The aim of this study was to test if respiratory occlusion tests predicted fluid responsiveness reliably in cardiac surgical patients with protective ventilation. This single-centre, prospective study, included 57 ventilated patients after elective coronary artery bypass grafting who were indicated for fluid expansion. Baseline echocardiographic measurements were obtained and patients with significant cardiac pathology were excluded. Cardiac index (CI), stroke volume and stroke volume variation were recorded using uncalibrated pulse contour analysis at baseline, after performing EEO and EIO tests and after volume expansion (7 mL/kg of succinylated gelatin). Fluid responsiveness was defined as an increase in cardiac index by 15%. Neither EEO, EIO nor their combination predicted fluid responsiveness reliably in our study. After a combined EEO and EIO, a cut-off point for CI change of 16.7% predicted fluid responsiveness with a sensitivity of 61.8%, specificity of 69.6% and ROC AUC of 0.593. In elective cardiac surgical patients with protective ventilation, respiratory occlusion tests failed to predict fluid responsiveness using uncalibrated pulse contour analysis.

Perioperative Fluid Management and Volume Assessment

Fluid therapy is an integral component of perioperative care and helps maintain or restore effective circulating blood volume. The principal goal of fluid management is to optimize cardiac preload, maximize stroke volume, and maintain adequate organ perfusion. Accurate assessment of volume status and volume responsiveness is necessary for appropriate and judicious utilization of fluid therapy. To accomplish this, static and dynamic indicators of fluid responsiveness have been widely studied. This review discusses the overarching goals of perioperative fluid management, reviews the physiology and parameters used to assess fluid responsiveness, and provides evidence-based recommendations on intraoperative fluid management.

New Developments in Continuous Hemodynamic Monitoring of the Critically Ill Patient

Hemodynamic monitoring is a cornerstone in the assessment of patients with circulatory shock. Timely recognition of hemodynamic compromise and proper optimisation is essential to ensure adequate tissue perfusion and maintain renal, hepatic, abdominal, and cerebral functions. Hemodynamic monitoring has significantly evolved since the first inception of the pulmonary artery catheter more than 50 years ago. Bedside echocardiography, when combined with noninvasive and minimally invasive technologies, provides tools to monitor and quantify the cardiac output to promptly react and improve hemodynamic management in an acute care setting. Commonly used technologies include noninvasive pulse-wave analysis, pulse-wave transit time, thoracic bioimpedance and bioreactance, esophageal Doppler, minimally invasive pulse-wave analysis, transpulmonary thermodilution, and pulmonary artery catheter. These monitoring strategies are reviewed here, along with detailed analysis of their operating mode, particularities, and limitations. The use of artificial intelligence to enhance performance and effectiveness of hemodynamic monitoring is reviewed to apprehend future possibilities.

Cardiac output monitoring - invasive and noninvasive

PURPOSE OF REVIEW

The purpose of this article is to review various contemporary cardiac output (CO) measurement technologies available and their utility in critically ill patients.

RECENT FINDINGS

CO measurement devices can be invasive, minimally invasive, or noninvasive depending upon their method of CO measurement. All devices have pros and cons, with pulmonary artery catheter (PAC) being the gold standard. The invasive techniques are more accurate; however, their invasiveness can cause more complications. The noninvasive devices predict CO via mathematical modeling with several assumptions and are thus prone to errors in clinical situations. Recently, PAC has made a comeback into clinical practice especially in cardiac intensive care units (ICUs). Critical care echocardiography (CCE) is an upcoming tool that not only provides CO but also helps in differential diagnosis. Lack of proper training and nonavailability of equipment are the main hindrances to the wide adoption of CCE.

SUMMARY

PAC thermodilution for CO measurement is still gold standard and most suitable in patients with cardiac pathology and with experienced user. CCE offers an alternative to thermodilution and is suitable for all ICUs; however, structural training is required.

Vasoplegic Shock Represents a Dominant Hemodynamic Profile of Multisystem Inflammatory Syndrome Following COVID-19 in Children and Adolescents

OBJECTIVES

The hemodynamic profile of multisystem inflammatory syndrome in children (MIS-C)-related shock remains poorly defined and, therefore, challenging to support with pharmacotherapy in the ICU. We aimed to evaluate the hemodynamic profile and vasoactive medication management used in MIS-C patients presenting to the ICU in shock and provide data from high-fidelity continuous cardiac output monitoring.

DESIGN

Single-center retrospective case-cohort study.

SETTING

Pediatric and cardiac ICU in a quaternary-care hospital.

PATIENTS

All patients who met U.S. Centers for Disease Control and Prevention criteria for MIS-C and who were admitted to the ICU between March 2020 and May 2021 required vasoactive support and were placed on continuous cardiac index (CCI) monitoring. Patients requiring extracorporeal life support were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among 52 children with MIS-C presenting in shock and requiring vasoactive support, 14 patients (27%) were placed on CCI monitoring. These 14 patients had hyperdynamic cardiac index (CI) and low indexed systemic vascular resistance (SVRi) in the first 24 hours with normalization of CI and improved SVRi within the subsequent 24 hours.

CONCLUSIONS

Further studies are needed to evaluate the difference between the use of vasoconstrictor versus vasodilators in pediatric patients with MIS-C because a phenotype with high CI and low SVRi may be important.

Contemporary Review of Hemodynamic Monitoring in the Critical Care Setting

Hemodynamic assessment remains the most valuable adjunct to physical examination and laboratory assessment in the diagnosis and management of shock. Through the years, multiple modalities to measure and trend hemodynamic indices have evolved with varying degrees of invasiveness. Pulmonary artery catheter (PAC) has long been considered the gold standard of hemodynamic assessment in critically ill patients and in recent years has been shown to improve clinical outcomes among patients in cardiogenic shock. The invasive nature of PAC is often cited as its major limitation and has encouraged development of less invasive technologies. In this review, the authors summarize the literature on the mechanism and validation of several minimally invasive and noninvasive modalities available in the contemporary intensive care unit. They also provide an update on the use of focused bedside echocardiography.

Pulmonary Artery Catheter Monitoring in Patients with Cardiogenic Shock: Time for a Reappraisal?

Cardiogenic shock represents one of the most dramatic scenarios to deal with in intensive cardiology care and is burdened by substantial short-term mortality. An integrated approach, including timely diagnosis and phenotyping, along with a well-established shock team and management protocol, may improve survival. The use of the Swan-Ganz catheter could play a pivotal role in various phases of cardiogenic shock management, encompassing diagnosis and haemodynamic characterisation to treatment selection, titration and weaning. Moreover, it is essential in the evaluation of patients who might be candidates for long-term heart-replacement strategies. This review provides a historical background on the use of the Swan-Ganz catheter in the intensive care unit and an analysis of the available evidence in terms of potential prognostic implications in this setting.

Temporal concordance between pulse contour analysis, bioreactance and carotid doppler during rapid preload changes

PURPOSE

We describe the temporal concordance of 3 hemodynamic monitors.

MATERIALS AND METHODS

Healthy volunteers performed preload changes while simultaneously wearing a non-invasive, pulse-contour stroke volume (SV) monitor, a bioreactance SV monitor and a wireless, wearable Doppler ultrasound patch over the common carotid artery. The sensitivity and specificity for detecting preload change over 3 temporal windows (early, middle and late) was assessed.

RESULTS

40 preload changes were recorded in total (20 increase, 20 decrease). Immediately, the wearable Doppler had high sensitivity (100%) and specificity (100%) for detecting preload change with an area under the receiver operator curve (AUROC) of 0.98 for both velocity time integral (VTI, 10.5% threshold) and corrected flow time (FTc, 2.5% threshold). The sensitivity, specificity and AUROC for non-invasive pulse contour were equally good (9% SV threshold). For bioreactance, a 13% SV threshold immediately detected preload change with a sensitivity, specificity and AUROC of 60%, 95% and 0.75, respectively. After two SV outputs following preload change, the sensitivity, specificity and AUROC of bioreactance improved to 70%, 90% and 0.85, respectively.

CONCLUSIONS

Carotid Doppler ultrasound and non-invasive pulse contour detected rapid hemodynamic change with equal accuracy; bioreactance improved over time. Algorithm-lag should be considered when interpreting clinical studies.

Reliability of Bioreactance and Pulse-Power Analysis in Measuring Cardiac Index in Patients Undergoing Cardiac Surgery With Cardiopulmonary Bypass

OBJECTIVES

Less-invasive and continuous cardiac output monitors recently have been developed to monitor patient hemodynamics. The aim of this study was to compare the accuracy, precision, and trending ability of noninvasive bioreactance-based Starling SV and miniinvasive pulse-power device LiDCOrapid to bolus thermodilution technique with a pulmonary artery catheter (TDCO) when measuring cardiac index in the setting of cardiac surgery with cardiopulmonary bypass (CPB).

DESIGN

A prospective method-comparison study.

SETTING

Oulu University Hospital, Finland.

PARTICIPANTS

Twenty patients undergoing cardiac surgery with CPB.

INTERVENTIONS

Cardiac index measurements were obtained simultaneously with TDCO intraoperatively and postoperatively, resulting in 498 measurements with Starling SV and 444 with LiDCOrapid.

MEASUREMENTS AND MAIN RESULTS

The authors used the Bland-Altman method to investigate the agreement between the devices and four-quadrant plots with error grids to assess the trending ability. The agreement between TDCO and Starling SV was qualified with a bias of 0.43 L/min/m² (95% confidence interval [CI], 0.37-0.50), wide limits of agreement (LOA, -1.07 to 1.94 L/min/m²), and a percentage error (PE) of 66.3%. The agreement between TDCO and LiDCOrapid was qualified, with a bias of 0.22 L/min/m² (95% CI 0.16-0.27), wide LOA (-0.93 to 1.43), and a PE of 53.2%. With both devices, trending ability was insufficient.

CONCLUSION

The reliability of bioreactance-based Starling SV and pulse-power analyzer LiDCOrapid was not interchangeable with TDCO, thus limiting their usefulness in cardiac surgery with CPB.

Blood pressure and cardiac output during caesarean delivery under spinal anaesthesia: a prospective cohort study

OBJECTIVES

We have previously established a method to measure transfer of nutrients between mother, placenta and fetus in vivo. The method includes measurements of maternal and fetal blood flow by Doppler ultrasound prior to spinal anaesthesia. Spinal anaesthesia affects maternal blood pressure and cardiac output. We aimed to determine the effect of spinal anaesthesia in mothers undergoing an elective caesarean section on blood pressure, heart rate and cardiac output, and whether cardiac output levels were comparable before induction of spinal anaesthesia and before delivery.

DESIGN

Prospective cohort study.

SETTING

Tertiary hospital in Norway.

PARTICIPANTS

76 healthy women with uneventful pregnancies undergoing an elective caesarean section.

INTERVENTIONS

We induced spinal anaesthesia with a standard prevention of hypotension including intravenous fluid coloading and phenylephrine infusion.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome measure was maternal cardiac output, and secondary outcome measures were invasive systolic blood pressure and heart rate. We measured heart rate and blood pressure by continuous invasive monitoring with a cannula in the radial artery. Cardiac output was estimated based on continuous arterial waveform. We compared maternal parameters 30 s before induction of spinal anaesthesia to 30 s before delivery.

RESULTS

Median age at delivery was 34.5 (range 21-43) years and 17 of 76 women were nulliparous. The most prevalent indications were previous caesarean section and maternal request. Among 76 included women, 71 had sufficient data for analysis of endpoints. Median cardiac output was 6.51 (IQR (5.56-7.54) L/min before spinal anaesthesia and 6.40 (5.83-7.56) L/min before delivery (p=0.40)). Median invasive systolic blood pressure increased from 128.5 (120.1-142.7) mm Hg to 134.1 (124.0-146.6) mm Hg (p=0.014), and mean heart rate decreased from 86.0 (SD 13.9) to 75.2 (14.2) (p<0.001).

CONCLUSIONS

Maternal cardiac output at the time of caesarean delivery is comparable to levels before induction of spinal anaesthesia.

TRIAL REGISTRATION NUMBER

NCT00977769.

Bioreactance and fourth-generation pulse contour methods in monitoring cardiac index during off-pump coronary artery bypass surgery

The pulmonary artery catheter (PAC) is considered the gold standard for cardiac index monitoring. Recently new and less invasive methods to assess cardiac performance have been developed. The aim of our study was to assess the reliability of a non-invasive monitor utilizing bioreactance (Starling SV) and a non-calibrated mini-invasive pulse contour device (FloTrac/EV1000, fourth-generation software) compared to bolus thermodilution technique with PAC (TDCO) during off-pump coronary artery bypass surgery (OPCAB). In this prospective study, 579 simultaneous intra- and postoperative cardiac index measurements obtained with Starling SV, FloTrac/EV1000 and TDCO were compared in 20 patients undergoing OPCAB. The agreement of data was investigated by Bland-Altman plots, while trending ability was assessed by four-quadrant plots with error grids. In comparison with TDCO, Starling SV was associated with a bias of 0.13 L min^-1 m^-2 (95% confidence interval, 95% CI, 0.07 to 0.18), wide limits of agreement (LOA, - 1.23 to 1.51 L min^-1 m^-2), a percentage error (PE) of 60.7%, and poor trending ability. In comparison with TDCO, FloTrac was associated with a bias of 0.01 L min^-1 m^-2 (95% CI - 0.05 to 0.06), wide LOA (- 1.27 to 1.29 L min^-1 m^-2), a PE of 56.8% and poor trending ability. Both Starling SV and fourth-generation FloTrac showed acceptable mean bias but imprecision due to wide LOA and high PE, and poor trending ability. These findings indicate limited reliability in monitoring cardiac index in patients undergoing OPCAB.

Updates in Hemodynamic Monitoring: A Review for Pharmacists

Vital signs are regularly monitored in hospitalized patients. In the intensive care unit (ICU), traditional non-invasive blood pressure monitoring and telemetry may not provide enough information to determine the etiology of hemodynamic instability or guide intervention. Arterial catheters remain the gold-standard for continuous blood pressure monitoring and are commonly used in ICU patients. Pulmonary artery catheters and central venous catheters are beneficial in select patient populations and provide more advanced and specific information about a patient's hemodynamics. However, neither are benign and can increase risk of complications such as infection, arrhythmias, pneumothorax and vascular or valvular damage. In the past 10 years, the development of reliable non-invasive (NICOM), or minimally-invasive (MICOM), cardiac output monitoring devices has accelerated. The MICOM devices require an arterial catheter to obtain hemodynamic values, whereas NICOM devices do not require any arterial or venous access. These devices have emerged to be particularly useful in evaluating and managing patients with suspected mixed shock. As these devices become more prevalent, it is imperative that clinical pharmacists become familiar with interpreting this data as it may have a substantial impact on medication selection and optimization. This review will discuss the basics of NICOM and MICOM devices, limitations with these methods of monitoring, and clinical application for pharmacists.

Use of pulse contour technology for continuous blood pressure monitoring in pediatric patients

OBJECTIVES

This study evaluates the accuracy of continuous blood pressure monitoring using pulse contour technology with the ClearSight monitoring device, a noninvasive alternative to placing an invasive arterial line, in pediatric patients.

METHODS

Children younger than 18 years admitted to a pediatric ICU, who required an arterial line, and fit into the ClearSight finger cuff were included. Blood pressure measurement for systolic, diastolic, and mean arterial pressures (MAP) obtained by the ClearSight device were compared with those obtained with the intra-arterial catheter as well as automated cuff measurements using the mixed-effects model. Analysis was conducted for entire cohort, and measurements obtained with and without vasopressor use.

RESULTS

There were 213 measurements from 10 patients. There was a statistically significant difference in systolic blood pressure when comparing arterial line and ClearSight systolic and diastolic measurements between the two methods (P < 0.001). There was no statistical difference between arterial MAP and ClearSight MAP (P = 0.957). Results were similar when ClearSight measurements were compared with automated cuff measurements. Both the vasopressor use and nonvasopressor use groups showed a statistically significant difference between arterial and ClearSight measurements for systolic and diastolic pressures, but not for the MAP.

CONCLUSIONS

Measurements of MAP obtained by the ClearSight device were almost identical to those obtained by the intra-arterial catheter. Although there was a difference in systolic blood pressures between the two methods, in those patients receiving inotropic support, the difference was within the range of what is considered acceptable in validating blood pressure devices.

CON: Pulmonary artery catheter use should be forgone in modern clinical practice

The pulmonary artery catheter (PAC) and its role in the practice of modern medicine remains to be questioned and has experienced a substantial decline in its use in the most recent decades. The complications associated to its use, the lack of consistency of the interpretation provided by the PAC among clinicians, the development of new hemodynamic methods, and the deleterious cost profile associated to the PAC are some of the reasons behind the decrease in its use. Since its introduction into clinical practice, the PAC and the data obtained from its use became paramount in the management of critically ill patients as well as for the high-risk/invasive procedures. Initially, many clinicians were under the impression that regardless the clinical setting, acquiring the information provided by the PAC justified its use, until a growing body of evidence demonstrated its lack of mortality and morbidity improvement, as well as several reports of the presence of difficulties—some of them fatal—during its insertion. The authors present an updated review discussing the futility of the PAC in current clinical practice, the complications associated to its insertion, the lack of mortality benefit in critically ill patients and cardiac surgery, as well as present alternative hemodynamic methods to the PAC.

Minimally Invasive Hemodynamic Assessment during Obstetric Hysterectomy for Invasive Placentation with Epidural Anesthesia

Background

The present study aimed to describe the evolution of hemodynamic parameters over time of patients with invasive placentation during their third trimester who were delivered via cesarean section and subsequently underwent obstetric hysterectomy under epidural anesthesia.

Methods

A prospective, descriptive, longitudinal, 11-month cohort study of 43 patients aged between 18 and 37 years who presented with invasive placentation. Minimal invasive monitoring was placed before the administration of epidural anesthesia for hemodynamic parameter tracking during the cesarean section. After delivery, the patients underwent an obstetric hysterectomy. Blood loss, hemodynamic parameters, and coagulation were managed via goal-directed therapy. Parameters were compared via repeated measures ANOVA and effect size estimation (Cohen's d).

Results

The mean age of the patients was 29.2 ± 3.4 years and was moderately overweight. They had minor cardiac index variance (P=NS, no significance), vascular systemic resistance index (NS), heart rate (P=NS), and median arterial pressure (P=NS). Differences were observed in the stroke volume index (P=0.015) due to moderately higher values (d = 0.3, P=0.016) in the middle of the surgery. Patients had lower cardiac index (d = -0.36, NS) and cardiac workload requirements (d = -0.29, P=0.034) toward the completion of surgery.

Conclusion

Patients who are in their third trimester and who subsequently underwent obstetric hysterectomy under epidural anesthesia had modest surgical hemodynamic variance and reduced cardiac workload requirements toward the end of the surgery.

A Single 60.000 IU Dose of Erythropoietin Does Not Improve Short-Term Aerobic Exercise Performance in Healthy Subjects: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial

Erythropoietin (EPO) boosts exercise performance through increase in oxygen transport capacity following regular administration of EPO but preclinical study results suggest that single high dose of EPO also may improve exercise capacity. Twenty-nine healthy subjects (14 males/15 females; age: 25 ± 3 years) were included in a randomized, double-blind, placebo-controlled crossover study to assess peak work load and cardiopulmonary variables during submaximal and maximal cycling tests following a single dose of 60.000 IU of recombinant erythropoietin (EPO) or placebo (PLA). Submaximal exercise at 40%/60% of peak work load revealed no main effect of EPO on oxygen uptake (27.9 ± 8.7 ml min^–1⋅kg^–1/ 37.1 ± 13.2 ml min^–1⋅kg^–1) versus PLA (25.2 ± 3.7 ml min^–1⋅kg^–1/ 33.1 ± 5.3 ml min^–1⋅kg^–1) condition (p = 0.447/p = 0.756). During maximal exercise peak work load (PLA: 3.5 ± 0.6 W⋅kg^–1 vs. EPO: 3.5 ± 0.6 W kg^–1, p = 0.892) and peak oxygen uptake (PLA: 45.1 ± 10.4 ml⋅min^–1 kg^–1 vs. EPO: 46.1 ± 14.2 ml⋅min^–1 kg^–1, p = 0.344) reached comparable values in the two treatment conditions. Other cardiopulmonary variables (ventilation, cardiac output, heart rate) also reached similar levels in the two treatment conditions. An interaction effect was found between treatment condition and sex resulting in higher peak oxygen consumption (p = 0.048) and ventilation (p = 0.044) in EPO-treated males. In conclusion, in a carefully conducted study using placebo-controlled design the present data failed to support the hypothesis that a single high dose of EPO has a measurable impact on work capacity in healthy subjects.

To Swan or Not to Swan: Indications, Alternatives, and Future Directions

The pulmonary artery catheter (PAC) has revolutionized bedside assessment of preload, afterload, and contractility using measured pulmonary capillary wedge pressure, calculated systemic vascular resistance, and estimated cardiac output. It is placed percutaneously by a flow-directed balloon-tipped technique through the venous system and the right heart to the pulmonary artery. Interest in the hemodynamic variables obtained from PACs paved the way for the development of numerous less-invasive hemodynamic monitors over the past 3 decades. These devices estimate cardiac output using concepts such as pulse contour and pressure analysis, transpulmonary thermodilution, carbon dioxide rebreathing, impedance plethysmography, Doppler ultrasonography, and echocardiography. Herein, the authors review the conception, technologic advancements, and modern use of PACs, as well as the criticisms regarding the clinical utility, reliability, and safety of PACs. The authors comment on the current understanding of the benefits and limitations of alternative hemodynamic monitors, which is important for providers caring for critically ill patients. The authors also briefly discuss the use of hemodynamic monitoring in goal-directed fluid therapy algorithms in Enhanced Recovery After Surgery programs.

Clinically applicable model-based method, for physiologically accurate flow waveform and stroke volume estimation

BACKGROUND AND OBJECTIVES

Cardiovascular dysfunction can be more effectively monitored and treated, with accurate, continuous, stroke volume (SV) and/or cardiac output (CO) measurements. Since direct measurements of SV/CO are highly invasive, clinical measures are often discrete, or if continuous, can require recalibration with a discrete SV measurement after hemodynamic instability. This study presents a clinically applicable, non-additionally invasive, physiological model-based, SV and CO measurement method, which does not require recalibration during or after hemodynamic instability.

METHODS AND RESULTS

The model's ability to predict flow profiles and SV is assessed in an animal trial, using endotoxin to induce sepsis in 5 pigs. Mean percentage error between beat-to-beat SV measured from an aortic flow probe and estimated by the model was -2%, while 90% of estimations fell within -24.2% and +27.9% error. Error between estimated and measured changes in mean SV following interventions was less than 30% for 4 out of the 5 pigs. Correlations between model estimated and probe measured flow, for each pig and hemodynamic interventions, was r² = 0.58 - 0.96, with 21 of the 25 pig intervention stages having r²  >  0.80.

CONCLUSION

The results demonstrate the model accurately estimates and tracks changes in flow profiles and resulting SV, without requiring model recalibration.

Evaluation of pulse wave transit time analysis for non-invasive cardiac output quantification in pregnant patients

Pregnant patients undergoing minimally-invasive foetoscopic surgery for foetal spina bifida have a need to be subjected to advanced haemodynamic monitoring. This observational study compares cardiac output as measured by transpulmonary thermodilution monitoring with the results of non-invasive estimated continuous cardiac output monitoring. Transpulmonary thermodilution-based pulse contour analysis was performed for usual anaesthetic care, while non-invasive estimated continuous cardiac output monitoring data were additionally recorded. Thirty-five patients were enrolled, resulting in 199 measurement time points. Cardiac output measurements of the non-invasive estimated continuous cardiac output monitoring showed a weak correlation with the corresponding thermodilution measurements (correlation coefficient: 0.44, R2: 0.19; non-invasive estimated continuous cardiac output: 7.4 [6.2-8.1]; thermodilution cardiac output: 8.9 [7.8-9.8]; p ≤ 0.001), while cardiac index experienced no such correlation. Furthermore, neither stroke volume nor stroke volume index correlated with the corresponding thermodilution-based data. Even though non-invasive estimated continuous cardiac output monitoring consistently underestimated the corresponding thermodilution parameters, no trend analysis was achievable. Summarizing, we cannot suggest the use of non-invasive estimated continuous cardiac output monitoring as an alternative to transpulmonary thermodilution for cardiac output monitoring in pregnant patients undergoing minimally-invasive foetoscopic surgery for spina bifida.

Effect of Hemodynamic Changes in Plasma Propofol Concentrations Associated with Knee-Chest Position in Spinal Surgery: A Prospective Study

Background

Anesthesia induction and maintenance with propofol can be guided by target-controlled infusion (TCI) systems using pharmacokinetic (Pk) models. Physiological variables, such as changes in cardiac output (CO), can influence propofol pharmacokinetics. Knee-chest (KC) surgical positioning can result in CO changes.

Objectives

This study aimed to evaluate the relationship between propofol plasma concentration prediction and CO changes after induction and KC positioning.

Methods

This two-phase prospective cohort study included 20 patients scheduled for spinal surgery. Two different TCI anesthesia protocols were administered after induction. In phase I (n = 9), the loss of consciousness (LOC) concentration was set as the propofol target concentration and CO changes following induction and KC positioning were quantified. In phase II (n = 11), based on data from phase I, two reductions in the propofol target concentration on the pump were applied after LOC and before KC positioning. Propofol plasma concentrations were measured at different moments in both phases: after induction and after KC positioning.

Results

Schnider Pk model showed a good performance in predicting propofol concentration after induction; however, after KC positioning, when a significant drop in CO occurred, the measured propofol concentrations were markedly underestimated. Intended reductions in the propofol target concentration did not attenuate HD changes. In the KC position, there was no correlation between the propofol concentration estimated by the Pk model and the measured concentration in plasma, as the latter was much higher (P = 0.013) while CO and BIS decreased significantly (P < 0.001 and P = 0.004, respectively).

Conclusions

Our study showed that the measured propofol plasma concentrations during the KC position were significantly underestimated by the Schnider Pk model and were associated with significant CO decrease. When placing patients in the KC position, anesthesiologists must be aware of pharmacokinetic changes and, in addition to standard monitoring, the use of depth of anesthesia and cardiac output monitors may be considered in high-risk patients.

Advances in Anesthesia Monitoring

During surgery, one of the primary functions of the anesthesiologist is to monitor the patient and ensure safe and effective conduct of anesthesia to provide the optimum operating conditions. Standard guidelines for perioperative monitoring have been firmly established by the American Society of Anesthesiologists. However, in recent years, new advances in technology has led to the development of many new monitoring modalities, especially involving the neurologic and cardiovascular systems. This article presents a targeted review to discuss the functions and limitations of these new monitors and how they are applied in the modern operating room setting.

Functional hemodynamic tests: a systematic review and a metanalysis on the reliability of the end-expiratory occlusion test and of the mini-fluid challenge in predicting fluid responsiveness

Background

Bedside functional hemodynamic assessment has gained in popularity in the last years to overcome the limitations of static or dynamic indexes in predicting fluid responsiveness. The aim of this systematic review and metanalysis of studies is to investigate the reliability of the functional hemodynamic tests (FHTs) used to assess fluid responsiveness in adult patients in the intensive care unit (ICU) and operating room (OR).

Methods

MEDLINE, EMBASE, and Cochrane databases were screened for relevant articles using a FHT, with the exception of the passive leg raising. The QUADAS-2 scale was used to assess the risk of bias of the included studies. In-between study heterogeneity was assessed through the I² indicator. Bias assessment graphs were plotted, and Egger’s regression analysis was used to evaluate the publication bias. The metanalysis determined the pooled area under the receiving operating characteristic (ROC) curve, sensitivity, specificity, and threshold for two FHTs: the end-expiratory occlusion test (EEOT) and the mini-fluid challenge (FC).

Results

After text selection, 21 studies met the inclusion criteria, 7 performed in the OR, and 14 in the ICU between 2005 and 2018. The search included 805 patients and 870 FCs with a median (IQR) of 39 (25–50) patients and 41 (30–52) FCs per study. The median fluid responsiveness was 54% (45–59). Ten studies (47.6%) adopted a gray zone analysis of the ROC curve, and a median (IQR) of 20% (15–51) of the enrolled patients was included in the gray zone. The pooled area under the ROC curve for the end-expiratory occlusion test (EEOT) was 0.96 (95%CI 0.92–1.00). The pooled sensitivity and specificity were 0.86 (95%CI 0.74–0.94) and 0.91 (95%CI 0.85–0.95), respectively, with a best threshold of 5% (4.0–8.0%). The pooled area under the ROC curve for the mini-FC was 0.91 (95%CI 0.85–0.97). The pooled sensitivity and specificity were 0.82 (95%CI 0.76–0.88) and 0.83 (95%CI 0.77–0.89), respectively, with a best threshold of 5% (3.0–7.0%).

Conclusions

The EEOT and the mini-FC reliably predict fluid responsiveness in the ICU and OR. Other FHTs have been tested insofar in heterogeneous clinical settings and, despite promising results, warrant further investigations.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2545-z) contains supplementary material, which is available to authorized users.

A double-knotted pulmonary artery catheter with large loop in the right internal jugular vein: A case report

Knotting of a pulmonary artery catheter (PAC) is a rare, but well-known complication of pulmonary artery (PA) catheterization. We report a case of a double-knotted PAC with a large loop in a patient with hepatocellular carcinoma (HCC) undergoing liver transplantation, which has been rarely reported in the literature. A PAC was advanced under pressure wave form guidance. PAC insertion was repeatedly attempted and the PAC was inserted 80 cm deep even though PAC should be normally inserted 45 to 55 cm deep. However, since no wave change was observed, we began deflating and pulling the balloon. At the 30-cm mark, the PAC could no longer be pulled. Fluoroscopy confirmed knotting of the PAC after surgery (The loop-formed PAC was shown in right internal jugular vein); thus, it was removed. For safe PA catheterization, deep insertion or repeated attempts should be avoided when the catheter cannot be easily inserted into the pulmonary artery. If possible, the insertion of PACs can be performed more safely by monitoring the movement of the catheter under fluoroscopy or transesophageal echocardiography.

Effects of hemodynamic monitoring using a single-use transesophageal echocardiography probe in critically ill patients - study protocol for a randomized controlled trial

BACKGROUND

Hemodynamic instability is one of the leading causes of intensive care unit (ICU) admission. Early stabilization of hemodynamics is associated with improved outcome. The monitoring used to guide hemodynamic support may influence the time needed to achieve stable hemodynamics. Visualization of the heart using echocardiography offers the advantage of direct measurement of cardiac volumes and ventricular function. A miniaturized monoplane transesophageal echocardiography (TEE) probe was developed, allowing for almost continuous qualitative hemodynamic TEE assessment (hTEE) after brief bedside training. The primary objective of the study is to assess whether hemodynamic monitoring using the hTEE technology shortens time to resolution of shock in ICU patients in comparison to standard monitoring using a central venous catheter, pulmonary artery catheter, or conventional echocardiography.

METHODS

Five hundred consecutive subjects with circulatory shock (low mean arterial blood pressure (MAP) and signs of organ hypoperfusion) at the time of ICU admission are included in the study. The subjects are randomly assigned to one of four groups using a 2 × 2 factorial design stratified by method of hemodynamic monitoring (hTEE vs standard hemodynamic monitoring) and frequency of hemodynamic assessments (minimum every 4 h vs standard of care). The primary study outcome is the time from study inclusion to resolution of circulatory shock, defined as MAP >  60 mmHg for ≥ 4 h after discontinuation of vasopressors and inotropes. The hTEE monitoring consists of the acquisition of three defined echocardiography views: Transgastric mid-esophageal short axis with measurement of fractional area change of left ventricle, mid-esophageal four-chamber view with measurement of the ratio of right to left ventricular area, and mid-esophageal ascending aortic short-axis view with measurement of the superior vena cava collapsibility index. In the control groups, monitoring modalities, including conventional TTE and TEE but not hTEE, are at the discretion of the treating physician. The interpretation of hemodynamic monitoring and the subsequent changes in patient management are recorded after each hemodynamic assessment. Differences in the primary and further secondary time-to-event outcomes will be assessed using a competing risk model accounting for the competing risk of death.

DISCUSSION

The effect of using echocardiography as a monitoring modality on relevant patient outcomes has not been established so far. The study at hand may be one of the first trials to provide detailed data on effectiveness and safety of echocardiography to guide treatment in patients with circulatory shock.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT02048566. Registered on January 29, 2014.

Prediction of fluid responsiveness in mechanically ventilated cardiac surgical patients: the performance of seven different functional hemodynamic parameters

Background

Functional hemodynamic parameters such as stroke volume and pulse pressure variation (SVV and PPV) have been shown to be reliable predictors of fluid responsiveness in mechanically ventilated patients. Today, different minimally- and non-invasive hemodynamic monitoring systems measure functional hemodynamic parameters. Although some of these parameters are described by the same name, they differ in their measurement technique and thus may provide different results. We aimed to test the performance of seven functional hemodynamic parameters simultaneously in the same clinical setting.

Methods

Hemodynamic measurements were done in 30 cardiac surgery patients that were mechanically ventilated. Before and after a standardized intravenous fluid bolus, hemodynamics were measured by the following monitoring systems: PiCCOplus (SVV_PiCCO, PPV_PiCCO), LiDCO_rapid (SVV_LiDCO, PPV_LiDCO), FloTrac (SVV_FloTrac), Philips Intellivue (PPV_Philips) and Masimo pulse oximeter (pleth variability index, PVI). Prediction of fluid responsiveness was tested by calculation of receiver operating characteristic (ROC) curves including a gray zone approach and compared using Fisher’s Z-Test.

Results

Fluid administration resulted in an increase in cardiac output, while all functional hemodynamic parameters decreased. A wide range of areas under the ROC-curve (AUC’s) was observed: AUC-SVV_PiCCO = 0.91, AUC-PPV_PiCCO = 0.88, AUC-SVV_LiDCO = 0.78, AUC-PPV_LiDCO = 0.89, AUC-SVV_FloTrac = 0.87, AUC-PPV_Philips = 0.92 and AUC-PVI = 0.68. Optimal threshold values for prediction of fluid responsiveness ranged between 9.5 and 17.5%. Lowest threshold values were observed for SVV_LiDCO, highest for PVI.

Conclusion

All functional hemodynamic parameters tested except for PVI showed that their use allows a reliable identification of potential fluid responders. PVI however, may not be suitable after cardiac surgery to predict fluid responsiveness.

Trial registration

NCT02571465, registered on October 7th, 2015 (retrospectively registered).

Comparison of three haemodynamic monitoring methods in comatose post cardiac arrest patients

OBJECTIVES

Haemodynamic monitoring during post arrest care is important to optimise treatment. We compared stroke volume measured by minimally-invasive monitoring devices with or without thermodilution calibration, and transthoracic echocardiography (TTE), and hypothesised that thermodilution calibration would give stroke volume index (SVI) more in agreement with TTE during targeted temperature management (TTM).

DESIGN

Comatose out-of-hospital cardiac arrest survivors receiving TTM (33 °C for 24 hrs) underwent haemodynamic monitoring with arterial pulse contour analyses with (PiCCO2®) and without (FloTrac^®/Vigileo^® monitor^®) transpulmonary thermodilution calibration. Haemodynamic parameters were collected simultaneously every fourth hour during TTM (hypothermia) and (normothermia). SVI was measured with TTE during hypothermia and normothermia. Bland-Altman analyses were used for determination of SVI bias (±1SD).

RESULTS

Twenty-six patients were included, of whom 77% had initial shockable rhythm and 52% discharged with good outcome. SVI (bias ±2SD) between PiCCO (after thermodilution calibration) vs FloTrac/Vigileo, TTE vs FloTrac/Vigileo and TTE vs PiCCO were 1.4 (±25.8), -1.9 (±19.8), 0.06 (±18.5) ml/m2 during hypothermia and 9.7 (±23.9), 1.0 (±17.4), -7.2 (±12.8) ml/m2 during normothermia. Continuous SVI measurements between PiCCO and FloTrac/Vigileo during hypothermia at reduced SVI (<35 ml/m2) revealed low bias and relatively narrow limits of agreement (0.5 ± 10.2 ml/m2).

CONCLUSION

We found low bias, but relatively wide limits of agreement in SV with PiCCO, FloTrac/Vigileo and TTE during TTM treatment. The methods are not interchangeable. Precision was not improved by transpulmonary thermodilution calibration during hypothermia.

Influence of injection rates of calibrating standard solution on monitoring pulse indicator continuous cardiac output

OBJECTIVE

This study aimed to investigate the influence of injection rates of calibrating standard solution on monitoring pulse indicator continuous cardiac output (PICCO, made in Germany), and thereby to provide significant references for clinical practice.

METHODS

A total of 108 critical patients in stroke intensive care unit were identified. All these participants received transesophageal cardiac color Doppler ultrasound, and within 15 min PICCO equipment was utilized to monitor the relevant parameters, by means of 0 °C calibrating standard solution, and the injection speeds were 2-4, 5-7, and 8-10 s. Besides, the monitoring indicators were as follows, cardiac index, global ejection fraction, global end diastolic volume index. The potential correlations were evaluated between PICCO and transesophageal cardiac color Doppler ultrasound.

RESULTS

All the data was available, and the monitored parameters of PICOO at 2-4, 5-7, and 8-10 s were positively correlated with the parameters obtained from transesophageal cardiac color Doppler ultrasound (P < 0.05). Specially, it is worth emphasizing that the best correlation between them could be provided when the injection rate was 2-4 s.

CONCLUSION

When the injection rate at 2-4 s, the parameters obtained by PICOO were much closer to that of transesophageal cardiac color Doppler ultrasound. Furthermore, the parameters of PICOO obtained at 2-4 s could better reflect cardiac function of patients.

Perioperative Goal-Directed Therapy Using Invasive Uncalibrated Pulse Contour Analysis

“Perioperative goal-directed therapy” (PGDT) aims at an optimization of basic and advanced global hemodynamic variables to maintain adequate oxygen delivery to the end-organs. PGDT protocols help to titrate fluids, vasopressors, or inotropes to hemodynamic target values. There is considerable evidence that PGDT can improve patient outcome in high-risk patients if both fluids and inotropes are administered to target hemodynamic variables reflecting blood flow. Despite this evidence, PGDT strategies aiming at an optimization of blood flow seem to be not well implemented in routine clinical care. The analysis of the arterial blood pressure waveform using invasive uncalibrated pulse contour analysis can be used to assess hemodynamic variables used in PGDT protocols. Pulse contour analysis allows the assessment of stroke volume (SV)/cardiac output (CO) and pulse pressure variation (PPV)/stroke volume variation (SVV) and thus helps to titrate fluids and vasoactive agents based on principles of “functional hemodynamic monitoring.” Pulse contour analysis-based PGDT treatment algorithms can be classified according to the hemodynamic variables they use as targets: PPV/SVV, SV/CO, or a combination of these variables. From a physiologic point of view, algorithms using both dynamic cardiac preload and blood flow variables as hemodynamic targets might be most effective in improving patient outcome. Future research should focus on the improvement of hemodynamic treatment algorithms and on the identification of patient subgroups in which PGDT based on uncalibrated pulse contour analysis can improve patient outcome.

Measures of Blood Hemoglobin and Hematocrit During Cardiac Surgery: Comparison of Three Point-of-Care Devices

OBJECTIVE

The primary objective was to compare I-Stat, HemoCue, and RapidLab in measurements of the hemoglobin concentration during cardiac surgeries using cardiopulmonary bypass.

DESIGN

Prospective analysis.

SETTING

Single-center, academic, tertiary care cardiovascular center.

PARTICIPANTS

Thirty-four consecutive patients undergoing cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

Blood samples have been collected intraoperatively, and the hemoglobin concentration in each sample was measured, or calculated, simultaneously by the 3 point-of-care devices, HemoCue, RapidLab, and I-Stat.

MEASUREMENTS AND MAIN RESULTS

Correlation coefficients from the regression analysis for HemoCue versus I-Stat, RapidLab versus HemoCue, and RapidLab versus I-Stat were 0.89, 0.96, and 0.88, respectively. Results of the Bland-Altman analysis of the hemoglobin concentration measurements for each device against one another (Fig 1) were as follows: RapidLab versus I-Stat (bias 0.42; 95% confidence interval [CI], -1.05 to 1.89), I-Stat versus HemoCue (bias 0.23; 95% CI, -1.14 to 1.59), and RapidLab versus HemoCue (bias 0.65; 95% CI, -0.17 to 1.47). It appears that I-Stat slightly underestimated the concentration of hemoglobin when compared with both RapidLab and HemoCue. The results of Bland-Altman analysis of each device to a mean Z value (Fig 2) were as follows: RapidLab versus Z (bias 0.36; 95% CI, -0.29 to 1.01), I-Stat versus Z (bias -0.07; CI -0.97 to 0.84), and HemoCue versus Z (bias -0.29; 95% CI, -0.86 to 0.28). Based on the 174 paired samples used for the Pearson moment analysis, the R² values for I-Stat versus HemoCue, I-Stat versus RapidLab, and RapidLab versus HemoCue were 0.79, 0.80, and 0.87, respectively CONCLUSIONS: These data support the interchangeability of these 3 devices for the intermittent intraoperative point-of-care assessment of hemoglobin concentrations in cardiac surgery patients. It is important, however, to consider the possible pitfalls associated with each device when making a clinical decision to transfuse.

Stroke Volume Monitoring: Novel Continuous Wave Doppler Parameters, Algorithms and Advanced Noninvasive Haemodynamic Concepts

PURPOSE OF REVIEW

Adequate oxygen delivery is essential for life, with hypoxia resulting in dysfunction, and ultimately death, of the cells, organs and organism. Blood flow delivers the oxygen bound in the blood, while haemodynamics is the science of blood flow. Stroke volume (SV) is the fundamental unit of blood flow, and reflects the interdependent performance of the heart, the vessels and the autonomic nervous system. However, haemodynamic management remains generally poor and predominantly guided by simple blood pressure observations alone.

RECENT FINDINGS

Doppler ultrasound measures SV with unequalled clinical precision when operated by trained personnel. Combining SV with BP measurements allows calculation of flow-pressure based measures which better reflect cardiovascular performance and allows personalised physiologic and pathophysiologic modelling consistent with Frank's and Starling's observations.

SUMMARY

Doppler SV monitoring and novel flow-pressure parameters may improve our understanding of the cardiovascular system and lead to improved diagnosis and therapy. This review examines the physics and practice of Doppler SV monitoring and its application in advanced haemodynamics.

Assessment of method agreement between two minimally invasive hemodynamic measurements in septic shock patients on high doses of vasopressor drugs. A preliminary study

BACKGROUND

Minimally invasive hemodynamic monitoring is still controversial among the methods used to assess the hemodynamic profile of the septic shock patient. The aim of this study was to test the level of agreement between two different devices.

METHODS

We collected 385 data entries during 12-hour intervals from four critically ill patients with septic shock and high doses of vasoactive therapy using two minimally invasive methods at the same time: Vigileo™ device which uses the pulse contour principle, and EV1000™ monitoring platform which uses the transpulmonary thermodilution principle. The studied parameters were Stroke Volume (SV), Cardiac Output (CO) and Mean Arterial Pressure (MAP). We tested the agreement by performing the visual examination of data patterns using graphs and studying the bias, limits of agreement and creating Bland-Altman plots. For assessing the systematic, proportional and random differences, we computed a Passing-Bablock regression with the CUSUM test for linearity.

RESULTS

The one sample t-Test for the differences between the two methods against the null value was statistically significant for the studied parameters (p < 0.0001). The Bland-Altman analysis found no agreement between the data obtained using the two techniques, with calculated error percent as high as 88.28% for SV, 82.02% for CO and 42.06% for MAP. The Passing-Bablock regression analysis tested positive for systematic differences, but this could not be accounted for.

CONCLUSION

We found no agreement between data obtained from the studied devices; therefore, these cannot be used interchangeably for critically ill septic shock patients on high doses of vasoactive substances.