Electrical Velocimetry Research Articles

Particle motion characteristics on the rotational flow pneumatic conveying of horizontal-vertical pipeline

In this study, a rotational flow device (rotational blade) is developed and installed in the upstream of the particle inlet with the aim of improving the efficiency and capacity of pneumatic conveying. Firstly, this study analyzed the energy-saving effect of rotational flow based on the pressure drop and power consumption. The results shown that the optimal velocity can be reduced by a maximum of 18.7 % and the power consumption coefficient can be reduced by a maximum of 9.8 %. Furthermore, the distributions of particle concentration, velocity and pulsation velocity are analyzed by using electrical capacitance tomography (ECT) and particle image velocimetry (PIV) system. It is found that the particle velocity and velocity pulsation intensity for rotational flow are higher, and they have the ability to enhance particle suspension. Then, the power spectrum of the particle pulsation velocity shown that the rotational flow exhibited higher peak value at lower frequencies, indicating the particles are not easily deposited at pipe bottom. Finally, the auto-correlation of particle pulsation velocity indicated that the particle motion is more stable and has a longer period at low particle concentrations. The skewness factor and probability density function of particle pulsation velocity indicated that the use of rotational blades makes the particle pulsation velocity to deviate from the Gaussian distribution.

Cardiovascular and cerebrovascular effects of caffeine maintenance in preterm infants during the transitional period.

Caffeine is routinely used for the prophylaxis of prematurity-related apnoeas. We aimed to evaluate the effect of caffeine maintenance on cardiovascular and cerebrovascular haemodynamics using a non-invasive multimodal monitoring in preterm infants during the transitional period. Infants <32 weeks' gestational age (GA) were enrolled in this observational prospective study. The following parameters were recorded before and after the administration of caffeine citrate 5 mg/kg using near-infrared spectroscopy, pulse oximetry and electrical velocimetry: heart rate, cardiac output, stroke volume, cardiac contractility, systemic vascular resistance (SVR), perfusion index, peripheral and cerebral oxygenation, cerebral fractional oxygen extraction, correlation index between cerebral oxygenation and heart rate (TOHRx, marker of cerebrovascular reactivity). Multilevel mixed-effects linear models were used to assess the impact of caffeine and of relevant clinical covariates on each parameter. Seventy-seven infants (mean GA 29.3 ± 2.5 weeks, mean birthweight 1148 ± 353 g) were included. Caffeine administration was associated with increased SVR (B = 0.623, p = 0.004) and more negative TOHRx values (B = -0.036, p = 0.022), which suggest improved cerebrovascular reactivity. Caffeine administration at maintenance dosage during postnatal transition is associated with increased systemic vascular tone and improved cerebrovascular reactivity. A possible role for caffeine-mediated inhibition of adenosine receptors may be hypothesized. This study provides a thorough and comprehensive overview of multiple cerebrovascular and cardiovascular parameters, monitored non-invasively by combining near-infrared spectroscopy, electrical velocimetry and pulse oximetry, before and after the administration of caffeine at maintenance dosage in preterm infants during postnatal transition. Caffeine was associated with an improvement in cerebrovascular reactivity and with a slight but significant increase in systemic vascular resistance, with no additional effects on other cardiovascular and cerebrovascular parameters. Our results support the safety of caffeine treatment even during a phase at risk for haemodynamic instability such as postnatal transition and suggest potential beneficial effects on cerebral haemodynamics.

Non-invasive monitoring of cardiac contractility: Trans-radial electrical bioimpedance velocimetry (TREV).

We describe methods and software resources for a bioimpedance measurement technique, 'trans-radial electrical bioimpedance velocimetry' (TREV) that allows for the non-invasive monitoring of relative cardiac contractility and stroke volume. After reviewing the relationship between the measurement and cardiac contractility, we describe the general recording methodology, which requires impedance measurements of the forearm. We provide open-source Jupyter-based software (operable on most computers) for deriving cardiac contractility from the impedance measurements. The software includes tools for removing variance associated with heart rate and respiration. We demonstrate the ability of this bioimpedance measurement for tracking beat-to-beat changes of contractility in a maximal grip force production task. Critically, the results demonstrate both a reactive increase in contractility with force production, and suggest there is a learned increase in contractility prior to grip onset, consistent with anticipatory allostatic autonomic regulation mediated by sympathetic inotropy. The method and software should be of broad utility for investigations of event-related cardiac dynamics in psychophysical studies.

In-line monitoring of mixing performance for smart processes in tubular reactors

This work is focused on the experimental analysis of the fluid dynamics characteristics of a tubular reactor equipped with Kenics static mixers working under turbulent flow conditions, with the specific aim of demonstrating the advantages of in-line monitoring tools for continuous process applications. Electrical Resistance Tomography, pressure transducers and Particle Image Velocimetry are employed to evaluate the mixing performance, the pressure drop and the flow field, respectively, considering the standard configuration of the mixers, consisting in mixing elements with alternating orientation, a single mixing element or multiple elements with the same orientation. The applicability of Electrical Resistance Tomography for offering insight into continuous reactors is assessed and the potential of monitoring the mixing performance inside the static mixers is shown. The experimental data suggest that alternatives to the standard element configurations might be adopted for optimizing the fluid mixing process, taking into account the mixing performances and the pressure drop, for which a novel correlation based on distributed and concentrated contributions is proposed.

Early fluid and norepinephrine resuscitation in septic acute kidney injury diminishes pro-inflammatory cytokine levels and kidney hypoperfusion in newborn pigs

Background and Objective: Sepsis is the most frequent risk factor for acute kidney injury (AKI) in critically ill infants. Whereas sepsis-induced AKI has been studied in several animal models, alterations in renal microcirculation are unclear. The objective of this study was to use the translational swine model to evaluate the changes in renal hemodynamics during the early phase of sepsis in the first week of life. We also examined the impact of early fluid and norepinephrine (NE) resuscitation on renal hemodynamics in newborn septic AKI. Methodology: Newborn pigs (3-7 days old) were randomly allocated to three groups; 1) Sham, 2) Sepsis (cecal ligation and puncture; CLP) without subsequent resuscitation, and 3) CLP-induced sepsis with fluid and vasopressor NE resuscitation. All animals underwent standard anesthesia induction, mechanical ventilation, and intravenous fluid. Cardiac output (COP) and GFR were measured non-invasively using electrical velocimetry and a transdermal system. The pigs were instrumented to measure the mean arterial pressure (MAP), total renal blood flow (tRBF), cortical perfusion (coPf), and medullary perfusion (mePf). Also, a fiber-optic probe was placed in the medulla to measure medullary tissue oxygen tension (tPO2). Baseline values were recorded for the above indices in all groups. In resuscitated animals, fluid bolus and NE infusion were started at the 4-h to maintain MAP within 15 mmHg from baseline. The pigs were euthanized after twelve hours. Results: Compared to baseline values, MAP and COP decreased by more than two-thirds in non-resuscitated sepsis, with a proportional increase in RVR and reduction in tRBF, coPf, mePf, and tPO2 in contrast to sham. CLP also decreased GFR and increased serum creatinine, BUN, and NGAL. A few tubular coagulative necroses were observed in the septic pigs. Changes in all these parameters, except tPO2, were ameliorated in resuscitated pigs. Resuscitation also attenuated sepsis-induced increase in the levels of serum C-reactive protein, inflammatory cytokines (IL-6, IL-8, IL-12, and IL-18), liver enzymes (aspartate aminotransferase and alanine aminotransferase), and renal NLRP3 inflammasome. Conclusions: Early implementation of resuscitation to maintain MAP, COP, and kidney perfusion lessens the degree of inflammation, AKI, and liver injury in newborn pigs. The discrepancy between medullary perfusion and oxygenation indicates that optimizing perfusion and blood flow does not always correlate with improved medullary oxygen delivery in newborns, especially in cases of increased metabolic demand, as in sepsis. Sepsis is a dynamic illness with phases of hypodynamic and hyperdynamic renal perfusion; therefore, management strategies would differ based on hemodynamic status. NIH R01DK120595 and R01DK127625 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Time series analysis of non-invasive hemodynamic monitoring data in neonates with hypoxic-ischemic encephalopathy.

Hemodynamic instability is common in neonates with hypoxic-ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH). Rewarming is a critical period and non-invasive circulatory monitoring may help guide cardiovascular supportive therapy. The aim of the study was to provide a comprehensive analysis of cardiac function parameters during TH and its relation to neurodevelopmental outcome. In a prospective, observational study, 26 neonates with moderate-severe HIE were enrolled, born between 2016 and 2019. A hemodynamic monitor based on electrical velocimetry (ICON, Osypka Medical GmbH, Berlin, Germany) was used. Heart rate (HR), stroke volume (SV), cardiac output (CO) data were recorded continuously throughout TH and rewarming. Neurological outcome was assessed at 2 years of age using the Bayley Scales of Infant Development II. edition. Favorable outcome was defined as >70 points on both the psychomotor and mental scales. Time-series analysis was used and features of cardiac function were described to perform logistic regression modeling for outcome prediction. Fourteen (54%) patients had favorable and 12 (46%) had adverse outcome. Data collection started from median [IQR] of 11.8 [7.0; 24.3] hours (h) of life and lasted until 84.0. [81.8; 87.0] h. During TH, the mean HR of the favorable outcome group was significantly lower than that of the adverse outcome group (86 ± 13/min vs. 104 ± 18/min, p = 0.01). During rewarming HR increased similarly in both groups. SV was unaffected by rewarming, and showed a slowly increasing trend. SV of the favorable outcome group was significantly higher compared to the adverse outcome group (1.55 ± 0.23 ml/kg vs. 1.29 ± 0.30 ml/kg, p = 0.035). In line with this, CO was similar in both groups (136 ± 27 ml/kg/min vs. 134 ± 36 ml/kg/min), and a significant 25% increase in CO was observed during rewarming. Based on multiple regression modeling, HR during TH was independently associated with neurological outcome (p = 0.023). Based on continuous hemodynamic monitoring, patients with adverse outcome have lower SV and higher HR to achieve similar CO to patients with favorable outcome during TH. HR during hypothermia is independently associated with the neurodevelopmental outcome.

Evaluation of four cardiac output measurement techniques during a modified passive leg raise maneuver in anesthetized dogs

Introduction: Modified passive leg raise maneuver (PLRM) is a successful volumetric predictor of fluid responsiveness in dogs during experimental induction and correction of hypovolemia using invasive pulmonary artery thermodilution (PACTD) for measuring cardiac output (CO). In this study, other CO methods, minimally-invasive esophageal Doppler (ESD), transesophageal echocardiography (TEE), arterial pressure waveform analysis (APW), noninvasive electrical velocimetry (EV), were investigated during PLRM in anesthetized dogs.

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.

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.

Comparison of cardiac output measurements using electrical velocimetry and lithium dilution with thermodilution in anesthetized dogs

Introduction: This study compared cardiac output (CO) measurements recorded by noninvasive electrical velocimetry (EVCO) and minimally invasive lithium dilution (LIDCO) with thermodilution (TDCO) during various hemodynamic states in anesthetized dogs.

Cardiac Output Measurement in Neonates and Children Using Noninvasive Electrical Bioimpedance Compared With Standard Methods: A Systematic Review and Meta-Analysis.

To systematically review and meta-analyze the validity of electrical bioimpedance-based noninvasive cardiac output monitoring in pediatrics compared with standard methods such as thermodilution and echocardiography. Systematic searches were conducted in MEDLINE and EMBASE (2000-2019). Method-comparison studies of transthoracic electrical velocimetry or whole body electrical bioimpedance versus standard cardiac output monitoring methods in children (0-18 yr old) were included. Two reviewers independently performed study selection, data extraction, and risk of bias assessment. Mean differences of cardiac output, stroke volume, or cardiac index measurements were pooled using a random-effects model (R Core Team, R Foundation for Statistical Computing, Vienna, Austria, 2019). Bland-Altman statistics assessing agreement between devices and author conclusions about inferiority/noninferiority were extracted. Twenty-nine of 649 identified studies were included in the qualitative analysis, and 25 studies in the meta-analyses. No significant difference was found between means of cardiac output, stroke volume, and cardiac index measurements, except in exclusively neonatal/infant studies reporting stroke volume (mean difference, 1.00 mL; 95% CI, 0.23-1.77). Median percentage error in child/adolescent studies approached acceptability (percentage error less than or equal to 30%) for cardiac output in L/min (31%; range, 13-158%) and stroke volume in mL (26%; range, 14-27%), but not in neonatal/infant studies (45%; range, 29-53% and 45%; range, 28-70%, respectively). Twenty of 29 studies concluded that transthoracic electrical velocimetry/whole body electrical bioimpedance was noninferior. Transthoracic electrical velocimetry was considered inferior in six of nine studies with heterogeneous congenital heart disease populations. The meta-analyses demonstrated no significant difference between means of compared devices (except in neonatal stroke volume studies). The wide range of percentage error reported may be due to heterogeneity of study designs, devices, and populations included. Transthoracic electrical velocimetry/whole body electrical bioimpedance may be acceptable for use in child/adolescent populations, but validity in neonates and congenital heart disease patients remains uncertain. Larger studies in specific clinical contexts with standardized methodologies are required.

Cardiac Output and Cerebral Oxygenation in Term Neonates during Neonatal Transition.

The immediate transition from foetus to neonate includes substantial changes, especially concerning the cardiovascular system. Furthermore, the brain is one of the most vulnerable organs to hypoxia during this period. According to current guidelines for postnatal stabilization, the recommended parameters for monitoring are heart rate (HR) and arterial oxygen saturation (SpO2). Recently, there is a growing interest in advanced monitoring of the cardio-circulatory system and the brain to get further objective information about the neonate’s condition during the immediate postnatal transition after birth. The aim of the present study was to combine cardiac output (CO) and brain oxygenation monitoring in term neonates after caesarean section in order to analyse the potential influence of CO on cerebral oxygenation during neonatal transition. This was a monocentric, prospective, observational study. For non-invasive cardiac output measurements, the electrical velocimetry (EV) method (Aesculon Monitor, Osypka Medical, CA, USA) was used. The pulse oximeter probe for SpO2 and HR measurements was placed on the right hand or wrist. The cerebral tissue oxygen index (cTOI) was measured using a NIRO-200NX monitor with the near-infrared spectroscopy (NIRS) transducer on the right frontoparietal head. Monitoring started at minute 1 and was continued until minute 15 after birth. At minutes 5, 10, and 15 after birth, mean CO was calculated from six 10 s periods (with beat-to-beat analysis). During the study period, 99 term neonates were enrolled. Data from neonates with uncomplicated transitions were analysed. CO showed a tendency to decrease until minute 10. During the complete observational period, there was no significant correlation between CO and cTOI. The present study was the first to investigate a possible correlation between CO and cerebral oxygenation in term infants during the immediate neonatal transition. In term infants with uncomplicated neonatal transition after caesarean section, CO did not correlate with cerebral oxygenation.

Sex related difference in cardiac output during neonatal transition in term neonates.

The immediate transition from foetus to neonate includes substantial changes especially concerning the cardiovascular system. As sex related differences have been shown in cardiovascular medicine, this topic warrants further investigation in neonatology. Aim: The aim of this present study was to measure cardiac output (CO) and cerebral oxygenation (cTOI) non-invasively in term neonates and to investigate potential sex related differences between female and male neonates after birth. This is a mono-centric prospective observational study. For CO-measurements, the electrical velocimetry method was used. The pulse oximetry for arterial oxygen saturation and heart-rate measurements was placed on the right hand or wrist. cTOI was measured using a NIRO 200NX monitor. The near-infrared spectroscopy probe was positioned on the right side of forehead in each infant. Monitoring started at minute 1 and was continued until minute 15 after birth. At minutes 5, 10, and 15 after birth, CO was calculated as an average out of six 10-second periods. 99 term neonates were enrolled. In our study population, we could identify 54 female and 45 male neonates. Males had higher cardiac output compared to females throughout the observational period, with a significant difference in minute 15 after birth (217, 95% CI: 203-231 mL/kg/min versus 178, 95% CI: 163-192 mL/kg/min; P<0.001). cTOI, SpO2, and HR did not differ between male and female neonates. The present work is the first to investigate sex related differences concerning cardiac output in term neonates during postnatal transition, showing a significantly higher cardiac output in male neonates 15 minutes after birth.

Hypocholesterolemia is a risk factor for reduced systemic vascular resistance reactivity during hemodialysis.

Intradialytic hypotension (IDH) is associated with high mortality. Peripheral vascular resistance and circulating blood volume are important factors in IDH; however, the effects of hemodialysis (HD) on vascular resistance in IDH remain unclear. We herein performed a retrospective observational cohort study to investigate changes in and factors related to vascular resistance during HD. A total of 101 HD patients were divided into two groups (Decreased blood pressure (BP) during HD group: N = 19, Nondecreased BP group: N = 82), and cardiac output was measured with electrical velocimetry (AESCLON) for 3 h. The systemic vascular resistance index (SVRI) was significantly decreased in the Decreased BP group, while the cardiac index was similar in both groups. A multivariate regression analysis identified hypocholesterolemia as a predictor of reduced vascular resistance reactivity during HD. Furthermore, a correlation was found between changes in the SVRI and cholesterol levels in patients with a higher Geriatric Nutritional Risk Index (GNRI) but not in those with a lower GNRI. The present results suggest that hypocholesterolemia contributes to reducing systematic vascular resistance reactivity during HD, which is an important predictor of a reduction in BP during HD. The relationship between hypocholesterolemia and vascular resistance may involve mechanisms other than malnutrition.

Electrical velocimetry (ICON cardiometry) assessment of hemodynamic changes associated with different inflation pressures during pediatric thoracoscopic surgery: a pilot study

Background Advances in endoscopic equipment and techniques have led to the use of minimally invasive thoracic surgery in an increasing number of pediatric surgical procedures. Logically, thoracoscopic surgery and anesthesia can induce significant physiologic changes; here comes the importance of an accurate, noninvasive cardiac output (CO) monitor for early diagnosis and management for any significant complications.Aims This study aimed to assess the effect of different intrathoracic pressures (ITP; insufflation pressures 4, 5, and 6 mmHg) during thoracoscopic surgeries in neonates and infants on hemodynamics using electrical velocimetry (ICON) as a noninvasive monitoring technique.Patients and methods This prospective pilot study was conducted in Abu El-Reesh Children’s Hospital, Kasr Al-Ainy Hospital, Faculty of Medicine, Cairo University, from November 2019 to January 2020. After obtaining ethical committee approval (D-6-2019) and registering at www.clinicaltrials.gov with the number NCT04131699, and after obtaining the consent of parents/legal guardians, 12 neonates and infants who presented for thoracoscopic surgery and met our selection criteria were included in the study. After standard premedication, monitoring, and anesthesia induction, for electrical velocimetry, an ‘ICON CARDIOTRONIC, OSYPKA MEDICAL’ continuous noninvasive CO monitor was attached to the patients according to the manufacturer’s instructions in neonates and infants. All patients’ data, including sex, height, and weight, were entered into the device, which estimated cardiovascular parameters at a 20-beat moving average recorded every 10 s. Cardiac index, CO, stroke volume, noninvasive arterial blood pressure, and heart rate readings had been taken in every patient. Records were taken before inflation of the chest as a baseline reference, 1 min after inflation of the chest as the ITP reaches 4 mmHg, then the ITP was increased to 5 mmHg, and the readings were taken after an extra 1 min. Finally, the ITP was increased to 6 mmHg, and the readings were taken after an additional 1 min.Results A total of 14 patients were screened for eligibility; of them, two patients were excluded for not meeting the inclusion criteria, and 12 patients were included. The median (interquartile range) age of patients was 4.5 (3–28) days. Sex distribution was equal (six males and six females). The cardiac index showed no significant increase with raising the pleural pressure (PP) by CO2 insufflation and postdeflation in comparison with baseline (preinsufflation). The CO showed no significant increase with raising the PP by CO2 insufflation in comparison with baseline (preinsufflation). Mean arterial blood pressure showed no significant change with gradual increase in PP and after deflation in comparison with preinflation readings; however, heart rate showed significant decrease after deflation in comparison with baseline (preinsufflation).Conclusion Hemodynamic stability was maintained during thoracoscopic surgery in neonates as measured by ICON. Further studies including systemic vascular resistance need to be done to give more explanation about hemodynamic affection during positive PP inflation. Moreover, different age groups, different patients’ positions, and patients with cardiac and pulmonary lesions need to be included to assess the various effects of pleural insufflation on these populations.

Noninvasive assessment of fluid responsiveness for emergency abdominal surgery in dogs with pulmonary hypertension: Insights into high-risk companion animal anesthesia.

ObjectiveOptimizing cardiac stroke volume during high-risk surgical anesthesia is of particular interest with regard to a therapeutic target to reduce the incidence of postoperative complications. However, intensive fluid management in critically ill small animals with pulmonary hypertension (PH) has been empirically performed, and thus it can be challenging. Stroke volume variation (SVV) has been used as a dynamic preload predictor of fluid responsiveness. We hypothesized that if SVV exhibited robust reliability in the setting of hemodynamically unstable condition, it would provide more precise information on fluid resuscitation to translate it into veterinary anesthesia. Thus the aim of this study was to investigate the utility of SVV measured by the electrical velocimetry (EV) method for predicting fluid responsiveness in dogs with PH.MethodsSixteen dogs undergoing emergency abdominal surgery and diagnosed with PH secondary to myxomatous mitral valve disease (MMVD) on preoperative transthoracic echocardiogram were included. Dogs were randomly assigned to 2 groups with and without inotropic cardiac support with dobutamine. Hemodynamic measurements including stroke volume and SVV derived from the EV device were performed under general anesthesia before (baseline) and after surgery (fluid challenge with a colloid solution defined by a SV increase of ≥ 10%).ResultsIn both groups, SVV elevated significantly after abdominal surgery compared with baseline. In dobutamine infused group, the SVV values decreased significantly after fluid challenge (P < 0.05) with a greater number of responders than saline infused control group (P < 0.01). Receiver operating curve analysis of SVV confirmed high positive predictive value for dogs during dobutamine infusion (P < 0.05; cut-off value of 15%; specificity 90%, sensitivity 82%).ConclusionsNoninvasive EV monitoring may be useful for the prediction of fluid responsiveness in critically ill dogs with left-sided heart failure-related PH. This normalization of dynamic preload indices, which could be achieved more precisely under inotropic support, may prevent further detrimental consequence of fluid loading.

Cardiovascular and cerebrovascular responses to cardio-respiratory events in preterm infants during the transitional period.

Non-invasive simultaneous multiparametric monitoring allows the in vivo evaluation of cerebral and cardiovascular haemodynamic responses to different types of recurrent episodes of intermittent hypoxia and/or bradycardia, also defined as cardio-respiratory events (CRE), in preterm neonates during postnatal transition. By decreasing left cardiac output, bradycardia further contributes to cerebral hypoxia during CRE. The presence of a haemodynamically significant patent ductus arteriosus results in a deeper impairment of cerebral oxygen status in response to CRE, whereas the brain-sparing remodelling of the fetal circulation resulting from placental insufficiency is associated with more favourable haemodynamic responses to intermittent hypoxia. During transition, the haemodynamic impact of CRE is influenced not only by the event type, but also by specific clinical features; this highlights the importance of developing individualized approaches to reduce the hypoxic burden in this delicate phase. The present observational prospective study aimed to investigate cerebral and cardiovascular haemodynamic responses to different types of cardio-respiratory events (CRE) in preterm infants during postnatal transition, as well as evaluate the impact of relevant clinical characteristics. Infants with gestational age (GA) <32 weeks and/or birth weight <1500 g were enrolled after birth. Cerebral oxygenation index (cTOI), fractional oxygen extraction (cFTOE), cardiac output (CO), cardiac contractility (iCON) and systemic vascular resistances (sVR) were simultaneously monitored over the first 72 h by near-infrared spectroscopy and electrical velocimetry. CRE were clustered into isolated bradycardia (IB), isolated desaturation (ID) and combined desaturation/bradycardia (DB). For each parameter, percentage changes from baseline (%Δ) were calculated. The impact of different CRE types and clinical variables on %Δ was evaluated with generalized estimating equations. In total, 1426 events were analysed. %ΔcTOI significantly differed among ID, IB and DB (P < 0.001), with the latter showing the greatest drop. %ΔcFTOE decreased significantly during DB (P < 0.001) and ID (P < 0.001) compared to IB. DB and IB were associated with more negative %ΔCO (P < 0.001) and more positive %ΔsVR (P < 0.001) compared to ID. A slight iCON reduction was observed during DB compared to ID (P = 0.043). Antenatal umbilical Doppler impairment, GA and the presence of a haemodynamically significant patent ductus arteriosus had a significant independent impact on %ΔcTOI, %ΔcFTOE and %ΔCO. During the transitional period, the haemodynamic responses to CRE are influenced by the event type and by specific neonatal characteristics, suggesting the importance of targeted individualized approaches for minimizing the risk of cerebral injury in the preterm population.

Systemic and regional cerebral perfusion in small infants undergoing minor lower abdominal surgery under awake caudal anaesthesia

Infants undergoing general anaesthesia have an increased risk of severe respiratory and cardiovascular critical events. Awake caudal anaesthesia is an alternative for small infants undergoing minor lower abdominal surgery. While clinical experience has shown stable intra-operative haemodynamic conditions, there are no studies evaluating systemic and regional cerebral perfusion during such a procedure. The purpose of this study was to evaluate the effects of awake caudal anaesthesia on systemic and regional cerebral perfusion in small infants. A prospective observational cohort study. Clinic of Anaesthesiology, University Children's Hospital, between November 2017 and June 2018. Twenty small infants (postmenstrual age 36 to 54 weeks, weight 1800 to 5700 g) scheduled for lower abdominal surgery under awake caudal anaesthesia were enrolled in this study. Standard monitoring was expanded to include cardiac index using electrical velocimetry and regional cerebral oxygen saturation using near infrared spectroscopy. The caudal block was performed with 0.3% ropivacaine 1 ml kg Hypotension was defined as mean arterial blood pressure (BP) less than 35 mmHg and regional cerebral desaturation as regional cerebral oxygen saturation less than 80% of baseline. Mean arterial BP, cardiac index and regional cerebral oxygen saturation parameters under awake caudal anaesthesia. Mean arterial BP, cardiac index and regional cerebral oxygen saturation remained above the predefined lower limits. No episodes of hypotension or regional cerebral desaturation were observed. Operation time was 35 ± 13 (range 20 to 71) min. The infants were discharged to the neonatal ward after the end of surgery, and milk was fed 22 ± 15 (range 6 to 55) min thereafter. Five preterm infants experienced self-limiting episodes of apnoea intra-operatively. The current study shows that awake caudal anaesthesia does not impair systemic and regional cerebral perfusion in small infants. German registry of clinical studies (DRKS-ID: 800015742).

Feasibility, reproducibility and accuracy of electrical velocimetry for cardiac output assessment in congenital heart disease

BackgroundNoninvasive cardiac output assessment is important for prognostication in patients with heart failure. Electrical velocimetry (EV), an impedance cardiography technique, can be used for noninvasive cardiac output assessment. The purpose of this study was to determine the feasibility, reproducibility and accuracy of cardiac output assessment by EV in adults with congenital heart disease (CHD). MethodsCross-sectional study of CHD patients that had simultaneous cardiac output assessment by Fick and EV (using Cardiotronic monitor, Osypka Medical). We divided the cohort into: Group 1 patients (n = 54) had hemodynamic assessment at rest only, while Group 2 patients (n = 7) had assessment both at rest and peak exercise. ResultsEV cardiac output assessment was feasible in 100% of the patients. There was good correlation between Fick-derived and EV-derived cardiac index (r = 0.89, p < 0.001) in Group 1. Among 26 patients in Group 1 that underwent cardiac output assessment pre- and post-intervention, there was no difference in the strength of correlation of Fick and EV cardiac output pre- and post-intervention (p-interaction 0.244) indicating good reproducibility of the technique. There was also modest correlation between Fick-derived and EV-derived cardiac index at rest (r = 0.68, p = 0.032), and peak exercise (r = 0.62, p = 0.055), in Group 2. ConclusionIn this study, we demonstrated the feasibility and accuracy of EV cardiac output assessment in adults with CHD. We also demonstrated, for the first time, that EV cardiac output assessment was reproducible under different loading conditions, and that EV can be used for the assessment of cardiac output augmentation at peak exercise.