Comparison of cardiac output measured by oesophageal Doppler ultrasonography or pulse pressure contour wave analysis

Cardiac output and regional-cerebral-oxygen-saturation in preterm neonates during immediate postnatal transition: An observational study

AIM

To examine potential correlations between cardiac output (CO) with cerebral-regional-oxygen-saturation (crSO₂ ) and cerebral-fractional-tissue-oxygen-extraction (cFTOE) during immediate foetal-to-neonatal transition in term and preterm neonates with and without respiratory support.

METHODS

Post hoc analyses of secondary outcome parameters of prospective observational studies were performed. We included neonates with cerebral near-infrared-spectroscopy (NIRS) monitoring and an oscillometric blood pressure measurement at minute 15 after birth. Heart rate (HR) and arterial oxygen saturation (SpO₂ ) were monitored. CO was calculated with Liljestrand and Zander formula and correlated with crSO₂ and cFTOE.

RESULTS

Seventy-nine preterm neonates and 207 term neonates with NIRS measurements and calculated CO were included. In 59 preterm neonates (mean gestational age (GA): 29.4 ± 3.7 weeks) with respiratory support, CO correlated significantly positively with crSO₂ and significantly negatively with cFTOE. In 20 preterm neonates (GA 34.9 ± 1.3 weeks) without respiratory support and in 207 term neonates with and without respiratory support, CO correlated neither with crSO₂ nor with cFTOE.

CONCLUSION

In compromised preterm neonates with lower gestational age and in need of respiratory support, CO was associated with crSO₂ and cFTOE, whereas in stable preterm neonates with higher gestational age as well as in term neonates with and without respiratory support, no associations were observed.

Estimation of cardiac stroke volume from radial pulse waveform by artificial neural network

BACKGROUND AND OBJECTIVES

Stroke volume (SV) and cardiac output (CO) are the key indicators for the evaluation of cardiac function and hemodynamic status during the perioperative period, which are very important in the detection and treatment of cardiovascular diseases. Traditional CO and SV measurement methods have problems such as complex operation, low precision and poor generalization ability.

METHODS

In this paper, a method for estimating stroke volume based on cascade artificial neural network (ANN) and time domain features of radial pulse waveform (SV_ANN) was proposed. The simulation datasets of 4000 radial pulse waveforms and stroke volume (SV_meas) were generated by a 55 segment transmission line model of the human systemic vasculature and a recursive algorithm. The ANN was trained and tested by 10-fold cross-validation, and compared with 12 traditional models.

RESULTS

Experimental results showed that the Pearson correlation coefficients and mean difference between SV_ANN and SV_meas (R=0.95, mean standard deviation (SD) = 0.00 ± 6.45) were better than the best results of the 12 traditional models. Moreover, as increasing the number of training samples, the performance improvement of the ANN (R=0.94(Δ + 0.04), mean ± SD = 0.00 ± 6.38(Δ± 2.02)) was better than the other best model, namely, multiple linear regression model (MLR) (R=0.93(Δ + 0.03), mean ± SD = 0.00 ± 6.99(Δ± 1.50)).

CONCLUSIONS

A method is proposed to estimate cardiac stroke volume by the ANN with time domain features of radial pulse wave. It avoids the complicated modeling process based on hemodynamics within traditional models, improves the estimation accuracy of SV, and has a good generalization ability.

Estimation of cardiac output variations induced by hemodynamic interventions using multi-beat analysis of arterial waveform: a comparative off-line study with transesophageal Doppler method during non-cardiac surgery

Multi-beat analysis (MBA) of the radial arterial pressure (AP) waveform is a new method that may improve cardiac output (CO) estimation via modelling of the confounding arterial wave reflection. We evaluated the precision and accuracy using the trending ability of the MBA method to estimate absolute CO and variations (ΔCO) during hemodynamic challenges. We reviewed the hemodynamic challenges (fluid challenge or vasopressors) performed when intra-operative hypotension occurred during non-cardiac surgery. The CO was calculated offline using transesophageal Doppler (TED) waveform (COTED) or via application of the MBA algorithm onto the AP waveform (COMBA) before and after hemodynamic challenges. We evaluated the precision and the accuracy according to the Bland & Altman method. We also assessed the trending ability of the MBA by evaluating the percentage of concordance with 15% exclusion zone between ΔCOMBA and ΔCOTED. A non-inferiority margin was set at 87.5%. Among the 58 patients included, 23 (40%) received at least 1 fluid challenge, and 46 (81%) received at least 1 bolus of vasopressors. Before treatment, the COTED was 5.3 (IQR [4.1-8.1]) l min-1, and the COMBA was 4.1 (IQR [3-5.4]) l min-1. The agreement between COTED and COMBA was poor with a 70% percentage error. The bias and lower and upper limits of agreement between COTED and COMBA were 0.9 (CI95 = 0.82 to 1.07) l min-1, -2.8 (CI95 = -2.71 to-2.96) l min-1 and 4.7 (CI95 = 4.61 to 4.86) l min-1, respectively. After hemodynamic challenge, the percentage of concordance (PC) with 15% exclusion zone for ΔCO was 93 (CI97.5 = 90 to 97)%. In this retrospective offline analysis, the accuracy, limits of agreements and percentage error between TED and MBA for the absolute estimation of CO were poor, but the MBA could adequately track induced CO variations measured by TED. The MBA needs further evaluation in prospective studies to confirm those results in clinical practice conditions.

The Validity of Carotid Doppler Peak Velocity and Inferior Vena Cava Collapsibility Index in Identifying the Fluid Responders in Mechanically Ventilated Septic Shock Patients

Introduction: Measures of carotid artery flow or inferior vena cava diameter were recently shown to predict fluid responsiveness. Both are relatively superficial large vessels which can provide straightforward ultrasound evaluation & high-qualityimages.Methods: Our study is a prospective observational study on 30 mechanically ventilated septic shock patients in ICUto assess the fluid responsivenessby measuring carotid Doppler peak velocity&respiratory variation in inferior vena cava diameter against the increase in the cardiac index by echocardiographic calculations as a reference. All patients were given a fluid bolus 7 ml/ Kg crystalloid solution within 30 minutes, static and dynamic indices which include CVP, MAP, pulse pressure, difference between diameter of IVC during inspiration and expiration (ΔIVC- d) & carotid Doppler peak velocity in a single respiratory cycle (ΔCDPV) were measured before (T0) & after (T1). Vasoactive drugs infusion rate and ventilation settings did not changed during follow up. Patients were categorized either fluid responders “R” or non-responders “NR” according to an increase in cardiac output “CO” (increase in CO > 15 %.Results: Comparing responders & Non responders group we found a significant difference in Cardiac output measures,MAP & Δ CDPV pre & post fluid boluses as (5.26±4.42 L/min Vs. 10.62±5.73 L/min, 69.48±9.70 mmHg Vs. 84.90±10.36 mmHg&24.43±11.87%Vs33.22±11.00%) respectively with P-value (0.007, 0.05&0.01) respectively, on the other side , ΔD-IVC & Δ CVP pre & post fluid boluses didn’t show any statistical difference as (11.91±9.41 % Vs. 13.51±9.56 %, 5.86±5.22 cmH2O Vs 7.22±4.82 cmH2O) with P-value (0.87&0.68)respectively.Δ CDPV increase in response to increased intravascular volume in R group showed sensitivity 81%, specificity 66.7%. APACHE II, SOFA day 0,5 didn’t showed any difference between the R & NR group (16.05±3.23 Vs 18.44±3.81, 11.48±2.82Vs12.11±2.80& 12.95±3.68Vs12.56±3.97) respectively with P-value (0.164,  0.625 & 0.79) respectively. Conclusion: ΔCDPV was a more precise & even easier assessment tool with better sensitivity and specificity for evaluation of fluid responsiveness than the ΔD-IVC in patients with septic shock upon mechanicalventilation. Also, ΔCDPV has a high correlation with SVI increasing parameters assessed by echocardiography after fluid boluses. On the other hand and in comparison, CVP showed low accuracy in predicting fluid responsiveness.    

Cerebral and systemic hemodynamic effect of recurring seizures

The increase in neuronal activity induced by a single seizure is supported by a rise in the cerebral blood flow and tissue oxygenation, a mechanism called neurovascular coupling (NVC). Whether cerebral and systemic hemodynamics are able to match neuronal activity during recurring seizures is unclear, as data from rodent models are at odds with human studies. In order to clarify this issue, we used an invasive brain and systemic monitoring to study the effects of chemically induced non-convulsive seizures in sheep. Despite an increase in neuronal activity as seizures repeat (Spearman’s ρ coefficient 0.31, P < 0.001), ictal variations of cerebral blood flow remained stable while it progressively increased in the inter-ictal intervals (ρ = 0.06, P = 0.44 and ρ = 0.22; P = 0.008). We also observed a progressive reduction in the inter-ictal brain tissue oxygenation (ρ =  − 0.18; P = 0.04), suggesting that NVC was unable to compensate for the metabolic demand of these closely repeating seizures. At the systemic level, there was a progressive reduction in blood pressure and a progressive rise in cardiac output (ρ =  − 0.22; P = 0.01 and ρ = 0.22; P = 0.01, respectively), suggesting seizure-induced autonomic dysfunction.

Evaluation of cardiac output variations with the peripheral pulse pressure to mean arterial pressure ratio

Cardiac output (CO) optimisation during surgery reduces post-operative morbidity. Various methods based on pulse pressure analysis have been developed to overcome difficulties to measure accurate CO variations in standard anaesthetic settings. Several of these methods include, among other parameters, the ratio of pulse pressure to mean arterial pressure (PP/MAP). The aim of this study was to evaluate whether the ratio of radial pulse pressure to mean arterial pressure (ΔPPrad/MAP) could track CO variations (ΔCO) induced by various therapeutic interventions such as fluid infusions and vasopressors boluses [phenylephrine (PE), norepinephrine (NA) or ephedrine (EP)] in the operating room. Trans-oesophageal Doppler signal and pressure waveforms were recorded in patients undergoing neurosurgery. CO and PPrad/MAP were recorded before and after fluid challenges, PE, NA and EP bolus infusions as medically required during their anaesthesia. One hundred and three patients (mean age: 52 ± 12 years old, 38 men) have been included with a total of 636 sets of measurement. During fluids challenges (n = 188), a positive correlation was found between ΔPPrad/MAP and ΔCO (r = 0.22, p = 0.003). After PE (n = 256) and NA (n = 121) boluses, ΔPPrad/MAP positively tracked ΔCO (r = 0.53 and 0.41 respectively, p < 0.001). By contrast, there was no relation between ΔPPrad/MAP and ΔCO after EP boluses (r = 0.10, p = 0.39). ΔPPrad/MAP tracked ΔCO variations during PE and NA vasopressor challenges. However, after positive fluid challenge or EP boluses, ΔPPrad/MAP was not as performant to track ΔCO which could make the use of this ratio difficult in current clinical practice.

Comprehensive in-hospital monitoring in acute heart failure: applications for clinical practice and future directions for research. A statement from the Acute Heart Failure Committee of the Heart Failure Association (HFA) of the European Society of Cardiology (ESC)

This paper provides a practical clinical application of guideline recommendations relating to the inpatient monitoring of patients with acute heart failure, through the evaluation of various clinical, biomarker, imaging, invasive and non-invasive approaches. Comprehensive inpatient monitoring is crucial to the optimal management of acute heart failure patients. The European Society of Cardiology heart failure guidelines provide recommendations for the inpatient monitoring of acute heart failure, but the level of evidence underpinning most recommendations is limited. Many tools are available for the in-hospital monitoring of patients with acute heart failure, and each plays a role at various points throughout the patient's treatment course, including the emergency department, intensive care or coronary care unit, and the general ward. Clinical judgment is the preeminent factor guiding application of inpatient monitoring tools, as the various techniques have different patient population targets. When applied appropriately, these techniques enable decision making. However, there is limited evidence demonstrating that implementation of these tools improves patient outcome. Research priorities are identified to address these gaps in evidence. Future research initiatives should aim to identify the optimal in-hospital monitoring strategies that decrease morbidity and prolong survival in patients with acute heart failure.

Norepinephrine reduces arterial compliance less than phenylephrine when treating general anesthesia-induced arterial hypotension

INTRODUCTION

During general anesthesia, arterial hypotension is frequent and may be an important contributor to perioperative morbidity. We assessed the effect of a 5 μg bolus of Norepinephrine (NA) when compared with 50 μg bolus of Phenylephrine (PE) administered to treat hypotension during maintenance anesthesia, on MAP, derived cardiac output and arterial stiffness parameters.

METHODS

Patients scheduled for a neurosurgical procedure under general anesthesia were prospectively included. Monitoring included invasive blood pressure, esophageal Doppler, and arterial tonometer used to estimate central aortic pressure with arterial stiffness parameters, such as augmentation index (Aix). After initial resuscitation, hypotensive episodes were corrected by a bolus administration of NA or PE in a peripheral venous line.

RESULTS

There were 269 bolus administrations of vasopressors (149 NA, 120 PE) in 47 patients with no adverse effects detected. A decrease in stroke volume (SV) was observed with PE compared with NA (-18 ± 9% vs. -14 ± 7%, P < 0.001). This decrease was associated with an increase in Aix, which was greater for PE than for NA (+10 ± 8% vs. +6 ± 6%, P < 0.0001), and a decrease in total arterial compliance greater for PE compared to NA (Ctot = SV/Central Pulse Pressure) (-35 ± 9% vs. -29 ± 10%, P < 0.001).

DISCUSSION

This study suggests that 5 μg of NA administered as a bolus in a peripheral venous line could treat general anesthesia-induced arterial hypotension with a smaller decrease in SV and arterial compliance when compared to PE.

Minimally Invasive Cardiac Output Monitoring: Agreement of Oesophageal Doppler, LiDCOrapid™ and Vigileo FloTrac™ Monitors in Non-Cardiac Surgery

There is lack of data about the agreement of minimally invasive cardiac output monitors, which make it impossible to determine if they are interchangeable or differ objectively in tracking physiological trends. We studied three commonly used devices: the oesophageal Doppler and two arterial pressure–based devices, the Vigileo FloTrac™ and LiDCOrapid™. The aim of this study was to compare the agreement of these three monitors in adult patients undergoing elective non-cardiac surgery. Measurements were taken at baseline and after predefined clinical interventions of fluid, metaraminol or ephedrine bolus. From 24 patients, 131 events, averaging 5.2 events per patient, were analysed. The cardiac index of LiDCOrapid versus FloTrac had a mean bias of −6.0% (limits of agreement from −51% to 39%) and concordance of over 80% to the three clinical interventions. The cardiac index of Doppler versus LiDCOrapid and Doppler versus FloTrac, had an increasing negative bias at higher mean cardiac outputs and there was significantly poorer concordance to all interventions. Of the preload-responsive parameters, Doppler stroke volume index, Doppler systolic flow time and FloTrac stroke volume variation were fair at predicting fluid responsiveness while other parameters were poor. While there is reasonable agreement between the two arterial pressure–derived cardiac output devices (LiDCOrapid and Vigileo FloTrac), these two devices differ significantly to the oesophageal Doppler technology in response to common clinical intraoperative interventions, representing a limitation to how interchangeable these technologies are in measuring cardiac output.

Respiratory variation in carotid peak systolic velocity predicts volume responsiveness in mechanically ventilated patients with septic shock: a prospective cohort study

Background

The evaluation of fluid responsiveness in patients with hemodynamic instability remains to be challenging. This investigation aimed to determine whether respiratory variation in carotid Doppler peak velocity (ΔCDPV) predicts fluid responsiveness in patients with septic shock and lung protective mechanical ventilation with a tidal volume of 6 ml/kg.

Methods

We performed a prospective cohort study at an intensive care unit, studying the effect of 59 fluid challenges on 19 mechanically ventilated patients with septic shock. Pre-fluid challenge ΔCDPV and other static or dynamic measurements were obtained. Fluid challenge responders were defined as patients whose stroke volume index increased more than 15 % on transpulmonary thermodilution. The area under the receiver operating characteristic curve (AUROC) was compared for each predictive parameter.

Results

Fluid responsiveness rate was 51 %. The ΔCDPV had an AUROC of 0.88 (95 % confidence interval (CI) 0.77–0.95); followed by stroke volume variation (0.72, 95 % CI 0.63–0.88), passive leg raising (0.69, 95 % CI 0.56–0.80), and pulse pressure variation (0.63, 95 % CI 0.49–0.75). The ΔCDPV was a statistically significant superior predictor when compared with the other parameters. Sensitivity, specificity, and positive and negative predictive values were also the highest for ΔCDPV, with an optimal cutoff at 14 %. There was good correlation between ΔCDPV and SVI increment after the fluid challenge (r = 0.84; p < 0.001).

Conclusions

ΔCDPV can be more accurate than other methods for assessing fluid responsiveness in patients with septic shock receiving lung protective mechanical ventilation. ΔCDPV also has a high correlation with SVI increase after fluid challenge.