Continuous Cardiac Output Measurement Research Articles

A Parameter Identification Approach towards Hemodynamics based on Capnography

Research question Pulse detection decisions during cardiopulmonary resuscitation (CPR) are commonly augmented by end-tidal CO2-concentration (etCO2) levels and trend as etCO2 is a surrogate measure of systemic blood flow during (CPR)1. However, ventilatory and circulatory parameters influence the interpretability of etCO2 heavily. Recently developed methods of continuous cardiac output measurement based on capnography are not applicable during CPR due to the required controlled ventilation settings2. In this study, a parameter identification for a model of CO2 transport during resuscitation is used to estimate cardiac output based on capnography and tidal flow. Methodology After development of a compartmental ordinary differential equation (ODE) model to represent CO2 transport during CPR, parameters such as airway dead space and the level of systemic perfusion are estimated by a multishooting parameter identification approach3. To evaluate the method, tests are conducted on experimental data from a porcine model (approved by an ethics committee vote of the Austrian Federal Ministry of Education, Science and Research (GZ: 2021-0.895.386)). The estimated level of systemic perfusion is compared visually to invasively measured mean arterial pressure due to a lack of continuous cardiac output measurements as a ground truth. Results For exemplary data from a female pig (weight 50.4 kg), airway resistance was estimated to 20.8 hPa s /L, compliance: 25.2 mL/hPa, and dead space: 109 mL. Changes in cardiac output can be identified qualitatively as shown in Fig. 1. Conclusion A validated, simple ODE model for CO2 extraction during CPR could contribute quantifying the impact of ventilatory parameters on etCO2 and elucidate CO2 production, storage and transport during cardiac arrest. Assumptions on CO2 production during cardiac arrest and redistribution in the body, and the lacking cardiac output measurements complicate the analysis. Conflicts of Interest All authors have no conflict of interest to declare.

Is Continuous Cardiac Output Measurement Using Thermodilution Reliable in the Critically Ill Patient?: Retraction.

Is Continuous Cardiac Output Measurement Using Thermodilution Reliable in the Critically Ill Patient?: Retraction.

Wearable and Noninvasive Device for Integral Congestive Heart Failure Management in the IoMT Paradigm.

Noninvasive remote monitoring of hemodynamic variables is essential in optimizing treatment opportunities and predicting rehospitalization in patients with congestive heart failure. The objective of this study is to develop a wearable bioimpedance-based device, which can provide continuous measurement of cardiac output and stroke volume, as well as other physiological parameters for a greater prognosis and prevention of congestive heart failure. The bioimpedance system, which is based on a robust and cost-effective measuring principle, was implemented in a CMOS application specific integrated circuit, and operates as the analog front-end of the device, which has been provided with a radio-frequency section for wireless communication. The operating parameters of the proposed wearable device are remotely configured through a graphical user interface to measure the magnitude and the phase of complex impedances over a bandwidth of 1 kHz to 1 MHz. As a result of this study, a cardiac activity monitor was implemented, and its accuracy was evaluated in 33 patients with different heart diseases, ages, and genders. The proposed device was compared with a well-established technique such as Doppler echocardiography, and the results showed that the two instruments are clinically equivalent.

Modification of a Transvalvular Microaxial Flow Pump for Instantaneous Determination of Native Cardiac Output and Volume

The current Impella CP pump used for mechanical circulatory support (MCS) in patients with cardiogenic shock (CS) cannot assess native cardiac output (CO) and left ventricular (LV) volumes. This data is valuable in facilitating device management and weaning. Admittance technology allows for accurate assessment of cardiac chamber volumes. This study tested the ability to engineer admittance electrodes onto an existing Impella CP pump to assess total and native CO in an instantaneous manner, as well as LV chamber volumes. Impella CP pumps were fitted with four admittance electrodes and placed in the LV of adult swine (n=9) subjected to three different hemodynamic conditions including Impella CP speed adjustments, administration of escalating doses of dobutamine, and microsphere injections into the left main artery to result in cardiac injury. CO by admittance electrodes was calculated from LV volumes and heart rate. In addition, CO was calculated in each instance via thermodilution, continuous CO (CCO) measurement, Fick's principle and aortic velocity-time integral (VTI) by echocardiography. Modified Impella CP pumps were placed in swine LV successfully. CO as determined by admittance electrodes was similar by trend with other methods of CO assessment, corrected for pump speed to calculate native CO, and calculated LV chamber volumes trended as expected in each experimental protocol. We report for the first time that an Impella CP pump can be fitted with admittance electrodes and used to determine total and native CO in various hemodynamic situations. Transvalvular mechanical circulatory support (MCS) devices such as the Impella CP do not have the ability to provide real-time information on native cardiac output (CO) and left ventricular (LV) volumes. This information is critical in device management and weaning in patients with cardiogenic shock (CS). We demonstrate for the first time, an Impella CP pump coupled with admittance electrodes are able to determine native CO, and left ventricle (LV) chamber volumes in multiple different hemodynamic situations such as Impella pump speed adjustments, escalating dobutamine administration, and cardiac injury from microsphere injection.

Non-invasive cardiac output monitoring with electrical velocimetry after cardiac surgery in infants.

Low cardiac output following cardiac surgery is a major determinant of outcome that may be improved by early detection, yet there are no widely accepted methods for its measurement in young children. We evaluated the feasibility of the routine use of electrical velocimetry, a non-invasive technique providing continuous measurement of cardiac output, in infants in the early postoperative period. With ethical approval and parental consent, infants undergoing cardiac surgery were recruited. The ICON electrical velocimetry monitor was attached on admission to the intensive care unit (ICU) and remained for up to 24h. A total of 15 infants were recruited, median age 3months (interquartile range (IQR) 0.5-7.5) and weight 4.8kg (IQR 3.9-7.1), undergoing various operations. Cardiac index had a weak correlation with arterial lactate (r=-0.24, p=0.02) and no correlation with blood pressure, central venous pressure or arteriovenous oxygen difference. Data were recorded for a median of 19h (range 5-24), with lead detachment or movement artefact the most common causes of data loss. There was marked minute-to-minute variability, with 25% of consecutive measurements having >5% variability. Cardiac index measured by electrical velocimetry in infants in the early postoperative period is impaired by frequent data loss and marked intrapatient variability. Our feasibility study suggests that it is unsuitable for use as a routine monitoring tool in the setting of postsurgical ICU care.

Comparing cardiac output measurements using electrical cardiometry versus phase contrast cardiac magnetic resonance imaging

BackgroundThere is a growing interest in using non-invasive electrical cardiometry (EC) for continuous cardiac output (CO) measurements in neonates and children. There is a lack of sufficient data to validate CO measured by EC with currently accepted noninvasive techniques such as cardiac MRI (CMRI) in children. ObjectivesTo assess the degree of agreement between CO measured by EC and CMRI in children. We hypothesized that there is a good degree of agreement between CO measured by EC and CMRI in children. MethodsA retrospective chart review was performed to include patients who had noninvasive CO measured using EC (ICON®) and CMRI at our children's hospital between Feb 2019 and May 2020. Anthropometric, clinical and CO data were collected and CMRI parameters such as flow measurements in the aorta and pulmonary artery were analyzed. Data was analyzed using a Bland-Altman plot to compare the agreement between the CO obtained by EC vs. CMRI in this cohort of patients. ResultsA total of 52 patients with cardiac disease who had data available from CMRI and ICON® were included. The median (IQR) age was 174 (99,201) months and male: female ratio was 1.2:1. A total of 34/52 (60 %) patients had congenital heart disease and 22 had history of surgical interventions prior to noninvasive CO measurements. The Bland-Altman analysis for CO values by both EC and CMRI produced a mean bias (SD) of 0.12 (2.73) l/min for ICON® and the 95 % limits of agreement were −5.229 to 5.473 l/min. The precision error was only 1.86 %. The Bland- Altman plot for reproducibility for CO values by EC produced a mean bias (SD) of 0.15 (0.41) l/min with limits of agreement of −0.66 to 0.97 l/min. The percentage error was 2.34 %. ConclusionsIn our cohort of cardiac patients, there was a good degree of agreement between noninvasive CO as measured by Electric Cardiometry and Cardiac MRI.

Neonatal Impedance Cardiography in Asphyxiated Piglets-A Feasibility Study.

ObjectivesImpedance cardiography (ICG) is a non-invasive method for continuous cardiac output measurement and has the potential to improve monitoring and treatment of sick neonates. PhysioFlow® is a signal-morphology ICG-system showing promising results in adults with low and high cardiac output, but no data from neonates or neonatal models exist. The aim of this study was to investigate PhysioFlow® feasibility in asphyxiated newborn piglets.MethodsFifteen piglets, under continuous arterial heart rate (HR) and blood pressure (BP) monitoring, were asphyxiated until asystole. Cardiopulmonary resuscitation was performed and the piglets monitored after return of spontaneous circulation (ROSC). Arterial lactate was measured at baseline, every 5 min throughout asphyxiation, at asystole, and at 10 min and later every 30 min after ROSC. PhysioFlow® measured cardiac stroke volume (SV) and HR, and calculated cardiac index (CI) (L/m2/min). Registrations with a signal quality < 75% were excluded, and registrations recorded for 30 min from start of asphyxia analyzed. Pearson correlations were calculated for CI; and HR, mean BP and blood lactate.ResultsThe piglets were asphyxiated for median (interquartile range) 30 (20–35) min and had a lactate at asystole of 15.0 (9.1–17.0) mmol/L. Out of a total of 20.991 registrations in all animals combined, there were 10.148 (48.3%) registrations with a signal quality ≥ 75%. Signal quality ≥ 75% varied in individual piglets from 7 to 82% of registrations. We analyzed 1.254 registrations recorded 30 min from initiation of asphyxia, i.e., in piglets with brief asphyxia times, this included cardiopulmonary resuscitation and post-ROSC observation. There was a positive correlation between CI and SVI (r = 0.90, p < 0.001), and between CI and HR (r = 0.446, p < 0.001). There was no correlation between CI, or mean BP or lactate (p = 0.98 and 0.51, respectively).ConclusionAbout half of ICG-registrations in asphyxiated piglets were of good quality. However, signal quality was highly variable between piglets. In total, there was a higher proportion of reliable ICG-registrations than reported from clinical delivery room studies using electrical velocimetry. Our data are physiologically plausible and supports further research evaluating PhysioFlow® for cardiac output monitoring in perinatal asphyxia. In particular, factors influencing inter-individual variations in signal quality should be explored.

Comparison of Cardiac Output Measurement by Electrical Velocimetry with Echocardiography in Extremely Low Birth Weight Neonates

Introduction: Electrical velocimetry (EV) offers a noninvasive tool for continuous cardiac output (CO) measurements which might facilitate hemodynamic monitoring and targeted therapy in low birth neonates, in whom other methods of CO measurement are not practicably feasible. Methods: This prospective observational study compared simultaneous cardiac output measurements by electrical velocimetry (COEV) with transthoracic echocardiography (COTTE) in extremely low birth weight (ELBW) neonates in the neonatal intensive care unit (NICU). Echocardiography was performed by 1 single examiner. Data were analyzed by Bland-Altman analysis and independent-samples analysis of variance. A mean percentage error (MPE) of <30% and limits of agreement (LOA) up to ±30% were considered clinically acceptable. Results: Thirty-eight ELBW neonates were studied and yielded 85 pairs of COEV and COTTE measurements. Bland-Altman analysis showed an overall bias (the mean difference) and LOA of −126 and −305 to +52 mL min−1, respectively, and an MPE of 66%. Patients with patent ductus arteriosus had a higher bias with LOA and MPE of −166.8, −370.7 to +37 mL min−1, and 69%, respectively. The overall true precision was 58%. Conclusion: This study showed high bias and lack of agreement between EV and TTE for measurement of CO in ELBW infants in NICU, limiting applicability of EV to monitor absolute values.

Cardiac output monitoring using transthoracic echocardiography in children after cardiac surgery-an observational study of feasibility and concordance with transpulmonary thermodilution

Abstract Background Transthoracic echocardiography (TTE) is commonly used after pediatric cardiac surgery to monitor cardiac function and adequacy of surgery; however it depends on the availability of good echo window and operator skill [1]. Transpulmonary thermodilution (TPTD) is feasible along with calibrated continuous cardiac output measurement in children but seldom used due to cost and the need for a specialized catheter [2]. We hypothesized that TTE would be as good as TPTD, but limited in feasibility following pediatric cardiac surgery. Hence, the concordance, agreement as well as feasibility and trending of cardiac output monitoring by TTE was compared against a reference TPTD method in real-world usage in children after congenital heart surgery. Methods This was a secondary analysis of data from a previously registered and conducted study in our unit. TPTD monitoring was instituted in children undergoing congenital heart disease repair on cardiopulmonary bypass with a 3F femoral arterial cannula and a central venous injectate temperature sensor. Cardiac output was also measured by transthoracic echocardiography by measurement of the left ventricular outflow tract (LVOT) diameter, LVOT velocity time integral (VTI) and the heart rate as previously described [3,4]. Measurements were taken after arrival in the ICU, and every 12 hours till after extubation. Correlation, Bland-Altman analysis and polar analysis was done for cardiac output measured by TPTD and TTE. Results TTE and TPTD measurements of cardiac output correlated well (Pearson's correlation coefficient 0.94; 95% CI 0.90–0.96) (Fig. 1A). Bland Altman analysis showed a mean bias of 0.15 l/min and upper and lower limits of agreement of 0.81 and −0.51 l/min respectively (Fig. 1B). Cardiac output measurement by TTE was possible in 72 instances while TPTD allowed measurement in all 113 instances. Hence, TTE was not feasible in 41 instances across 14 patients, including 19 instances in acyanotic and 22 instances in cyanotic patients. Polar analysis revealed acceptable trending. Conclusions TTE derived cardiac output demonstrated good correlation, minimal bias and narrow limits of agreement versus TPTD, and was feasible in most cases. This suggests TTE is an acceptable cardiac output measurement modality post pediatric cardiac surgery, as in adults [5]. TPTD-based continuous cardiac output monitoring might have a complementary role in pediatric cardiac critical care, particularly in high risk cases. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Institutional Special Research Grant from Postgraduate Institute of Medical Education and Research, Chandigarh, India. Figure 1

Elevated Heart Rate and Pain During a Cold Pressor Test Correlates to Pain Catastrophizing.

To understand the variable response to pain, researchers have examined the change in cardiovascular measures to a uniform painful stimulation. Pain catastrophizing is the tendency to magnify or exaggerate pain sensations, and it affects the outcome of rehabilitation in a clinical setting. Its effect on cardiovascular changes during a painful stimulus is unclear. Twenty-four healthy human participants completed the study. All participants completed a cold pressor test while subjective pain intensity was measured with a numeric pain scale from 0-10. Continuous cardiac output measurements were obtained with finger-pulse plethysmograph waveform analysis. The measurements included systolic and diastolic blood pressure, heart rate averaged over 30s intervals. Pain catastrophizing and anxiety were assessed using the pain catastrophizing scale (PCS), and Spielberger's State-Trait Anxiety Inventories, respectively. Peak pain was correlated to pain catastrophizing (r = 0.628, p < 0.01). There was a strong correlation between change in heart rate (HR) and subjective peak pain (r = 0.805, p < 0.01), total PCS (r = 0.474, p < 0.05), and the helplessness subscale of the PCS (r = 0.457, p < 0.05). Peak pain and catastrophizing explained a significant amount of the variance for the change in HR during the cold pressor test (R2 of 0.649 and 0.224 respectively, p = 0.019). These novel findings demonstrate a psycho-physiological relationship between cardiovascular changes and pain catastrophizing. Further research should include participants with subacute or persistent pain.

Objective Assessment of Physiologic Alterations Associated With Hemodynamically Significant Patent Ductus Arteriosus in Extremely Premature Neonates.

Delay in closure of ductus arteriosus in postnatal life may lead to serious consequences and complications in an extremely premature neonate secondary to hemodynamic alterations in regional blood flow pattern in various organs. Despite the widespread recognition amongst neonatologists to identify a hemodynamically significant patent ductus arteriosus (hsPDA) early in the postnatal course, there is lack of consensus in its definition and thus the threshold to initiate treatment. Echocardiographic assessment of PDA shunt size and volume combined with neonatologists' impression of clinical significance is most frequently used to determine the need for treatment of PDA. Common clinical signs of hsPDA utilized as surrogate for decreased tissue perfusion may lag behind early echocardiographic signs. Although echocardiogram allows direct assessment of PDA shunt and hemodynamic alterations in the heart, it is limited by dependence on pediatric cardiologist availability, interobserver variation and isolated time point assessment. Electrical cardiometry (EC) is a non-invasive continuous real time measurement of cardiac output by applying changes in thoracic electrical impedance. EC has been validated in preterm newborns by concomitant transthoracic echocardiogram assessments and may be beneficial in studying changes in cardiac output in premature newborns with hsPDA. Alterations in perfusion index derived from continuous pulse oximetry monitoring has been used to study changes in cardiac performance and tissue perfusion in infants with PDA. Near infrared spectroscopy (NIRS) has been used to objectively and continuously assess variations in renal, mesenteric, and cerebral oxygen saturation and thus perfusion changes due to diastolic vascular steal from hsPDA in preterm neonates. Doppler ultrasound studies measuring resistive indices in cerebral circulation indicate disturbance in cerebral perfusion secondary to ductal steal. With recent trends of change in practice toward less intervention in care of preterm newborn, treatment strategy needs to be targeted for select preterm population most vulnerable to adverse hemodynamic effects of PDA. Integration of these novel ways of hemodynamic and tissue perfusion assessment in routine clinical care may help mitigate the challenges in defining and targeting treatment of hsPDA thereby improving outcomes in extremely premature neonates.

The prognosis evaluation of sICAM-1, KL-6 combined with EVLWI in severe pneumonia patients with acute respiratory distress syndrome

Objective To evaluate the prognostic value of extravascular lung water index (EVLWI), soluble intercellular adhesion molecule-1(sICAM-1) and Krebs yon den lungen-6 (KL-6) in severe pneumonia patients with Severe Acute Respiratory Syndrome (ARDS). Methods A prospective study was conducted in Respiratory Intensive Care Unit of the Affiliated Zhengzhou Central Hospital of Zhengzhou University from October 2017 to February 2020. The study included 65 severe pneumonia patients with ARDS, who was performed by measurement of pulse index continuous cardiac output and survived more than 3days after admission. The Extravascular Lung Water Index（EVLWI）, sICAM-1, KL-6 and Oxygenation Index(OI) on 1st, 3rd and 5th day were detected. APACHE Ⅱ score, patient survival events (days) and survival outcome were recorded. Correlation analysis between EVLWI, sICAM-1, KL-6 and OI was performed on the 1st，3rd and 5th day after admission. Independent risk factors of mortality in severe pneumonia patients with ARDS were analyzed by multiple logistic regression. Receiver operating characteristic curve was drawn，and the prognostic value of each parameter was assessed finally. Results The PCT, EVLWI, sICAM-1, KL-6 and APACHE Ⅱ score in the death group were significantly higher than those in the survival group (P 0.05）. These parameters including levels of EVLWI, sICAM-1, KL-6, Procalcitonin and APACHE Ⅱ score in the death group were significantly higher than those in the survival group on the 1st，3rd and 5th day (P<0.05), whereas the OI was significantly lower than that of the survival group on the 3rd and 5th day (P<0.05). Logistic regression analysis showed that EVLWI, sICAM-1, KL-6 level were significantly related with the mortality of these patients. The levels of sICAM-1, kl-6 and EVLWI on 1st，3rd and 5th day after RICU admission showed a significant negative correlation with OI (P<0.001). Whereas, The levels of sICAM-1, kL-6 on 1st，3rd and 5th day showed a significant positive correlation with EVLWI (P<0.001). The sensitivity and specificity of sICAM-1, KL-6 combined with EVLWI in prognosis evaluation on 1st，3rd and 5th day were 75.0%，84.4%, 85.0%，66.7%，80.0%，86.7%, respectively. The AUC was 0.864，0.881，0.892 on 1st，3rd and 5th day, respectively (P<0.001), which had a better prognostic value than each of them. Conclusions EVLWI, sICAM-1 and KL-6 were independent risk factors for the prognosis of severe pneumonia patients with ARDS. The combination of EVLWI, sICAM-1 and KL-6 might be important in early predicting the prognosis of the 28d mortality. © 2021 Chinese Medical Association. All rights reserved.

Reliability of Pulse Contour Cardiac Output Analysis in a Piglet Model of Multi-step Intra-abdominal Hypertension

BackgroundPulse contour cardiac output (PCCO) analysis is a minimally invasive technique for continuous cardiac output (CO) measurement monitoring. PCCO requires calibration by transpulmonary thermodilution (TPTD). Studies showed good agreement between PCCO, TPTD CO and CO measured by pulmonary artery thermodilution (PATD) during stable hemodynamics. However, data are limited in patients with intra-abdominal hypertension (IAH). The objective is to compare the agreement between PCCO, TPTD CO, and PATD CO in a piglet model of multi-step IAH. Materials and methodsTen female domestic piglets were enrolled in this study. IAH was induced by stepwise carbon dioxide inflation into peritoneal cavity in anesthetized piglets. Following baseline registrations, intra-abdominal pressure (IAP) was increased and maintained at each IAP plateau of 10, 20, 30, and 40 mmHg for 15 min before CO measurements. CO was measured by PATD and simultaneously by 2 femoral artery PCCO catheters. One PCCO catheter was recalibrated by TPTD at each IAP plateau while the other was only calibrated at baseline. ResultsIn pooled data of different IAP stages, TPTD CO and recalibrated PCCO (R-PCCO) showed excellent correlation (r2 = 0.94 and 0.93) and small bias (−0.09 and −0.09 L/min), respectively, compared with PATD CO. However, PCCO without recalibration (NR-PCCO) were not accurate during IAH (r2 = 0.58, bias: +0.32 L/min). When IAP increased to 30 mmHg, NR-PCCO failed to agree with PATD CO (r2 = 0.47, bias: +0.52 L/min). On the contrary, a clinically accepted agreement between TPTD CO, R-PCCO, and PATD CO was observed at different IAP stages. ConclusionsTPTD CO and R-PCCO agreed with PATD CO in this piglet model of multi-step IAH. On the contrary, NR-PCCO failed to agree with PATD CO when IAP increased to 30 mmHg or more. PCCO analysis needs recalibration in this condition.

Continuous Estimation of Acute Changes in Preload Using Epicardially Attached Accelerometers.

A miniaturized accelerometer can be incorporated in temporary pacemaker leads which are routinely attached to the epicardium during cardiac surgery and provide continuous monitoring of cardiac motion during and following surgery. We tested if such a sensor could be used to assess volume status, which is essential in hemodynamically unstable patients. An accelerometer was attached to the epicardium of 9 pigs and recordings performed during baseline, fluid loading, and phlebotomy in a closed chest condition. Alterations in left ventricular (LV) preload alter myocardial tension which affects the frequency of myocardial acceleration associated with the first heart sound ( fS1). The accuracy of fS1 as an estimate of preload was evaluated using sonomicrometry measured end-diastolic volume (EDV[Formula: see text]). Standard clinical estimates of global end-diastolic volume using pulse index continuous cardiac output (PiCCO) measurements (GEDV[Formula: see text]) and pulmonary artery occlusion pressure (PAOP) were obtained for comparison. The diagnostic accuracy of identifying fluid responsiveness was analyzed for fS1, stroke volume variation (SVV[Formula: see text]), pulse pressure variation (PPV[Formula: see text]), GEDV[Formula: see text], and PAOP. Changes in fS1 correlated well to changes in EDV[Formula: see text] ( r2=0.81, 95%CI: [0.68, 0.89]), as did GEDV[Formula: see text] ( r2=0.59, 95%CI: [0.36, 0.76]) and PAOP ( r2=0.36, 95%CI: [0.01, 0.73]). The diagnostic accuracy [95%CI] in identifying fluid responsiveness was 0.79 [0.66, 0.94] for fS1, 0.72 [0.57, 0.86] for SVV[Formula: see text], and 0.63 (0.44, 0.82) for PAOP. An epicardially placed accelerometer can assess changes in preload in real-time. This novel method can facilitate continuous monitoring of the volemic status in open-heart surgery patients and help guiding fluid resuscitation.

Low cardiac output measured by bioreactance and adverse outcome in preterm infants with birth weight less than 1250 g

BackgroundRecently a new continuous non-invasive cardiac output measurement, bioreactance, has become available. Bioreactance measurement of cardiac output has been shown to correlate with left ventricular output detected by echocardiography in healthy term and preterm neonates. AimsOur aim was to correlate cardiac output measurements by bioreactance in the first 48 h of life with adverse outcomes attributable to hypoperfusion (peri/intraventricular haemorrhage (PIVH) and/or necrotising enterocolitis (NEC)) in the cohort of extremely preterm infants. Study designA prospective observational cohort study. SubjectsPreterm infants with birth weight less than 1250 g. Outcome measuresCardiac output was measured between six and 48 h of age by bioreactance. Our primary outcome was a difference in cardiac output between infants with an adverse outcome attributable to hypoperfusion (Group 1), and infants without the predefined adverse outcome (Group 2). ResultsThere were 39 infants enrolled in the study. There were six infants in Group 1. These infants had a significantly lower minimal cardiac output measurement compared to Group 2 (mean 36.7 ml/kg/min vs 64.5 ml/kg/min, p = .0006). The mean cardiac output in Group 1 was significantly lower on day one of life, followed by a significant increase in cardiac output on day two of life compared to Group 2. ConclusionsInfants with birth weight less than 1250 g and PIVH and/or NEC had significantly lower cardiac output compared to infants without these complications on day one of life. This low cardiac output was then followed by a significant increase on day two of life.

The Effect of Surgical Patient Positions on Plet Variability Index, Perfusion Index and Noninvasive Continuous Cardiac Output Measurement Method in Voluntary Breathing Volunteers

Amaç: Cerrahi prosedür için verilen farklı pozisyonlar doku perfüzyonunda ve kardiyak outputta değişikliklere neden olabilir. Bu çalışmada spontan solunuma sahip katılımcılarda plet değişkenlik indeksinin (PVI), perfüzyon indeks (PI) ve noninvaziv sürekli kardiyak output ölçüm yöntemi (EscCO) nin farklı cerrahi pozisyonlardaki değişimlerini araştırmayı amaçladık.Materyal ve Metod: 20 katılımcıdan oluşan bir sağlıklı birey grubu prospektif gözlemsel çalışmaya dahil edildi. Sırasıyla Supin, 30 derece baş yukarı, 45 derece baş yukarı, 20 derece Trendelenburg, 20 derece ters-Trendelenburg, ve pron pozisyonları uygulandı. Her pozisyon arası 10 ar dk olacak şekilde süre tutuldu. Her pozisyon değişikliğinden önce gönüllüler sırtüstü pozisyona alındı ve beş dakika dinlendikten sonra yeni pozisyon verildi. Pozisyon değişiminden sonraki 5. dakika PI, PVI, EscCO, SpO2 değerleri kayıt altına alındı.Bulgular: Katılımcıların farklı pozisyondayken ölçülen PI, PVI ile EscCO değerlerinde istatistiksel olarak anlamlı bir fark bulunamadı.Sonuç: Bu çalışma, PI, PVI ile EscCO nun tüm cerrahi pozisyonlarda herhangi bir değişikliğe uğramadığını ve her üç parametrenin de spontan solunumuna sahip genç sağlıklı bireylerde pozisyondan etkilenmediği ortaya koymuştur.

Cardiac Output Values and Correlation of Renal Injury with Neutrophil Gelatinase-Associated Lipocalin Levels in Off-Pump Coronary Artery Bypass Patients.

ObjectiveTo investigate the correlation between cardiac output values and renal neutrophil gelatinase-associated lipocalin (NGAL) levels as a biomarker of renal ischemia.MethodsForty patients, who underwent off-pump coronary artery bypass (OPCAB) surgery and in whom the positioning of the heart was fixed with simple suspension sutures without a mechanical stabilizer, were included in the study. Continuous cardiac output (CO) measurements were recorded using the arterial pressure waveform analysis method (FloTrac sensor system) in the perioperative period. CO was recorded every minute during non-anatomical cardiac positioning for left anterior descending artery (LAD), diagonal artery (D), circumflex artery (Cx), and right coronary artery (RCA) bypasses. Serum NGAL samples were analyzed in the preoperative, perioperative, and postoperative periods.ResultsThe CO values measured at various non-anatomical cardiac positions during distal anastomosis for LAD, D, Cx, and RCA were significantly lower than pre- and postoperative values measured with the heart in normal anatomical position (3.45±0.78, 2.9±0.71, 3.11±0.56, 3.19±0.81, 5.03±1.4, and 4.85±0.78, respectively, P=0.008). There was no significant difference between CO values measured at various non-anatomical cardiac positions during distal anastomosis. Although there was no significant correlation between NGAL levels and age, duration of surgery, preoperative CO, D-CO, RCA-CO, and postoperative CO measurements, there was a significant correlation between NGAL levels and LAD-CO (P=0.044) and Cx-CO (P=0.018) at the postoperative 12th hour.ConclusionFull revascularization may be achieved by employing the OPCAB technique while using simple suspension sutures without a mechanical stabilizer and by providing safe CO levels and low risk of renal ischemia.

Acute Soy Supplementation Improves 20-km Time Trial Performance, Power, and Speed.

Isoflavones, a chemical class of phytoestrogens found in soybeans and soy products, may have biological functions similar to estradiol. After binding with ERβ or perhaps independently of estrogen receptors, isoflavones may augment vascular endothelial relaxation, contributing to improved limb blood flow. To determine if acute fermented soy extract supplementation influences 20-km time trial cycling performance and cardiac hemodynamics compared with a placebo. Subjects included 25 cyclists and triathletes (31 ± 8 yr, V˙O2peak: 55.1 ± 8.4 mL·kg·min). Each subject completed a V˙O2peak assessment, familiarization, and two 20-km time trials in randomized order after ingestion of a fermented soy extract supplement or placebo. The fermented soy extract consisted of 30 g powdered supplement in 16 fl. ounces of water. The placebo contained the same quantities of organic cocoa powder and water. Each trial consisted of 60 min of rest, 30 min at 55% Wpeak, and a self-paced 20-km time trial. Soy supplementation elicited a faster time to 20-km completion (-0.22 ± 0.51 min; -13 s), lower average HR (-5 ± 7 bpm), and significantly greater power (7 ± 3 W) and speed (0.42 ± 0.16 km·h) during the last 5 km of the time trial compared with placebo. Analysis of the results by relative fitness level (<57 vs ≥ 57 mL⋅kg⋅min) indicated that those with a higher level of fitness reaped the largest performance improvement alongside a reduced HR (-5 ± 7 bpm). Ingestion of a fermented soy extract supplement improved sprint-distance performance through improvements in both power and speed. For those with great aerobic fitness, soy supplementation may help to decrease cardiac demand alongside performance improvement.

New generation continuous cardiac output monitoring from carbon dioxide elimination

BackgroundThere is continuing interest among clinicians in the potential for advanced hemodynamic monitoring and “goal directed” intravenous fluid administration guided by minimally-invasive cardiac output measurement to reduce complication rates in high risk patients undergoing major surgery. However, the adoption of the available technologies has been limited, due to cost, complexity and reliability of measurements provided. We review progress in the development of new generation methods for continuous non-invasive monitoring of cardiac output from measurement of carbon dioxide elimination in ventilated patients using the Differential Fick method.Main textThe history and underlying theoretical basis are described, and its recent further development and implementation using modern generation anesthesia monitoring and delivery systems by two separate but parallel methods, termed “Capnotracking” and “Capnodynamics”. Both methods generate breath-by-breath hands-free cardiac output monitoring from changes in carbon dioxide elimination produced by automatic computerized modulation of respiratory rate delivered by an electronic ventilator. Extensive preclinical validation in animal models of hemodynamic instability, with implanted ultrasonic flow probes for gold standard reference measurements, shows this approach delivers reliable, continuous cardiac output measurement in real time. The accuracy and precision of measurement by the Capnodynamic method were maintained under a wide range of both hemodynamic and respiratory conditions, including inotropic stimulation, vasodilatation, hemorrhage, caval compression, alveolar lavage, changes in tidal volume and positive end-expiratory pressure, and hypercapnia, with only brief derangement observed in a model of lower body ischemia involving release of prolonged aortic occlusion by an intra-aortic balloon. Phase 2 testing of a Capnotracking system in patients undergoing cardiac surgery and liver transplantation has achieved a percentage error of agreement with thermodilution of +/− 38.7% across a wide range of hemodynamic states.ConclusionsProgress in development of these technologies suggest that a robust, automated and reliable method of non-invasive cardiac output monitoring from capnography is close at hand for use in major surgery and critical care. The great advantage of this approach is that it can be fully integrated into the anesthesia machine and ventilator, using components that are already standard in modern anesthesia and intensive care workstations, and should be virtually hands-free and automatic.

The predictive value of sFlt-1 combined with extravascular lung water index in severe pneumonia patients with acute respiratory distress syndrome complicated with septic shock

Objective To evaluate the prognosis value of plasma soluble vascular endothelial growth factor receptor (sFlt-1) combined with extravascular lung water index (EVLWI) in acute respiratory distress syndrome (ARDS) complicated with septic shock caused by severe pneumonia. Methods A retrospective analysis was conducted in Respiratory Intensive Care Unit of the Affiliated Zhengzhou Central Hospital of Zhengzhou University from January 2015 to July 2017. The study included 52 severe pneumonia patients with ARDS complicated with septic shock, who was performed by measurement of pulse index continuous cardiac output (PICCO) and survived more than 3 days after admission. According to the 28-day mortality, these patients were divided into the survival group (31 cases) and the death group (21 cases). PICCO was used to record the EVLWI level. The plasma level of sFlt-1 was measured by enzyme-linked immunosorbent assay (ELISA). Acute physiology and chronic health evaluation II (APACHE II) score and sequential organ failure assessment (SOFA) score were calculated. Independent risk factors were analyzed by multiple logistic regression. Correlation analysis between plasma sFlt-1 and EVLWI and APACHE II values was performed on the 1st, 2nd and 3rd day after admission. Receiver operating characteristic curve (ROC) was calculated, and the prognostic value of each parameter was assessed. Results The blood lactate, APACHE II score and SOFA score in the death group were significantly higher than those in the survival group at RICU admission (P<0.05), and the length of RICU stay was significantly shorter than that in the survival group (P<0.05), while differences in other clinical characteristics between the two groups were not statistically significant. The levels of EVLWI, sFlt-1 and blood lactate, APACHE II score and SOFA score in the death group were significantly higher than those in the survival group on the 1st, 2nd and 3rd day (all P<0.05), whereas the PaO2/FiO2 was significantly lower than that of the survival group on the 2nd and 3rd day (all P<0.05). Logistic regression analysis showed that sflt-1 level and EVLWI were significantly related with the patient mortality. The levels of sFlt-1 on day 1, 2 and 3 after RICU admission were positively related to EVLWI and APACHE II score (all P<0.01). The sensitivity and specificity of sFlt-1 combined with EVLWI in prognosis evaluation were 89.7%, 78.2% and 86.3%, 75.7%, respectively. The AUC of sFlt-1 combined with EVLWI was 0.875 and 0.856 on the 1st and 3rd day, respectively (all P<0.01), which had a better prognostic value than each of them. Conclusions SFlt-1 could be used as a biomarker of mortality for severe pneumonia patients with ARDS complicated with septic shock. The combination of sFlt-1 and EVLWI might be important in early prediction of the prognosis of the 28-day mortality in patients with ARDS complicated with septic shock caused by severe pneumonia. Key words: sFlt-1; PICCO; Extravascular lung water index; Septic shock; Prognosis