Physiologic effects of rotary blood pumps

Die Verwendung axialer Blutpumpen zur Unterstützung des Herzens bei fortgeschrittenem Herzversagen nimmt zu, einerseits aufgrund der steigenden Prävalenz von Herz- und Kreislauferkrankungen, andererseits aufgrund der Verfügbarkeit von kleinen und klinisch anwendbaren axialen Pumpen. Diese Systeme finden entweder Verwendung als Herzunterstützung im Rahmen der Überbrückung und Vorbereitung auf eine Herztransplantation; andererseits um die Erholung des Herzens zu unterstützen. Axiale Blutpumpen zeichnen sich durch einen niedrig pulsatilen oder sogar non-pulsatilen Blutfluss aus, was zahlreiche Fragen zur Physiologie aufwirft. Im ersten Teil dieser Dissertation wird ein Überblick über die Herzkreislaufunterstützung mittels Kunstherzen gegeben und anhand der aktuellen Literatur die Physiologie eines Kreislaufs mit herabgesetzter oder fehlender Pulsatilität beschrieben. Im zweiten Teil werden eigene wissenschaftliche Arbeiten zum Thema präsentiert. Das erste Projekt behandelt den Effekt einer axialen Blutpumpe auf die koronare Durchblutung, den myocardialen Sauerstoffverbrauch und den pulmonalen Blutfluss bei Schafen. Eine in vivo Untersuchung wurde an 10 Schafen durchgeführt, um koronare Durchblutungsparameter wie auch die Druck- und Blutflussverhältnisse sowohl mit als auch ohne Unterstützung mit axialen Blutpumpen invasiv zu messen und zu vergleichen. Ein DeBakey VAD wurde implantiert und die systemischen und koronaren Blutflüsse sowohl unter baseline Bedingungen als auch unter unterschiedlichen Levels der Pumpeneinstellungen gemessen. Unsere Resultate weisen darauf hin, dass der Blutfluss der Koronararterien nicht mit den Veränderungen an den Einstellungen der Pumpe korreliert. Die Veränderungen des pulmonalen Blutflusses können auf einen herabgesetzten pulmonalen Gefäßwiderstand hindeuten; ein Effekt der zu einer Stabilisierung des rechten Ventrikels beitragen könnte; möglicherweise auch aufgrund einer Veränderung der Geometrie des linken Ventrikels durch die Volumsentlastung. Gerade diese gleich bleibende koronare Durchblutung bei sinkendem Sauerstoffverbrauch des Myocards kann zur Herzerholung beitragen. Das zweite Projekt befasst sich mit Ansaugereignissen im linken Ventrikel, die während dieser Form der Herzunterstützung gleichermaßen wie bei einer Unterstützung mit pulsatilen Kunstherzen auftreten können. Endokardiales Ansaugen kann zu einem möglichen linksventrikulärem Kollaps, Ansaugen der Wand des Ventrikels und nachfolgender rechtsventrikulärer Dysfunktion führen. Ziel dieses Teils der Dissertation war es, schwere ventrikuläre Arrhythmien darzustellen und zu klassifizieren, die in einem zeitlichen Bezug zu Ansaugereignissen stehen. Das Ziel war es, ventrikuläre Arrhythmien in einem zeitlichen Zusammenhang mit Ansaugereignissen darzustellen und diese morphologisch zu klassifizieren. Als Einteilung wurde die monomorphe ventriculäre Tachycardie (Einzelschlag) von der monomorphen ventriculären Tachycardie (als Serie) und von der polymorphen ventriculären Tachycardie abgegrenzt. 19 Patienten wurden einer Gesamtzahl von 57 Untersuchungen unterzogen. Die Elektrokardiogramme wurden semi-manuell mittels eines graphischen Interface in der Software Matlab klassifiziert. Es zeigte sich, dass die exzessive Entleerung des linken Ventrikels während des Supports ventrikuläre Arrhythmien induzieren kann; es gibt Hinweise für einen Anstieg von arrhythmischen Ereignissen nach dem Ansaugen. Dabei handelt es sich um einen transienten Effekt, der 5 Minuten nach dem Suction-Ereignis nicht mehr nachweisbar ist. Diese EKG Veränderungen haben einen plötzlichen Beginn und sind schwerwiegende ventrikuläre Ereignisse, die in aller Regel nach Ende des Ansaugens verschwinden. Wenngleich weiterführende Untersuchungen notwendig sind, um festzustellen inwieweit diese Arrhythmien mit einem schlechteren Outcome korrelieren, weisen diese Daten darauf hin, dass Ansaugereignisse vermieden werden sollen. Zahlreiche rezente Studien haben das exzellente Potential axialer Herzpumpen gezeigt, um Patienten mit terminalem Herzversagen mit einer guten Lebensqualität unterstützen zu können. Die Effekte eines niedrig pulsatilen Kreislaufs oder einer überhaupt pulslosen Zirkulation auf die Physiologie sind noch nicht vollständig bekannt. Diese Daten sollen dazu beitragen, zukünftige Rotationspumpensysteme weiter zu verbessern.The use of rotary blood pumps for assistance of advanced heart failure continues to increase with the growing prevalence of the disease itself and the availability of small and clinically applicable devices. These devices are used either as cardiac support prior to transplantation or to assist the recovery of the heart. As rotary blood pumps produce a non-pulsatile flow, several questions concerning the physiology of pulseless circulation are remaining. The first part of this thesis gives an introduction on cardiac support with blood pumps and covers the physiology of low-pulse and pulseless circulation under rotary assist device support according to the literature. The second part is presenting own scientific work on the topic of the thesis. Two publications resulted from the scientific focus, the first project deals with the effects of left ventricular assist device therapy on coronary hemodynamics, myocardial oxygen consumption and pulmonary blood flow in sheep. An in vivo investigation in 10 sheep was done to determine invasively measured coronary perfusion data as well as pressure and flow conditions under cardiovascular assistance and compare the effects of the assistance to physiologic circulatory conditions. A DeBakey VAD® was implanted and systemic and coronary hemodynamic measurements were performed at defined baseline conditions where up to five levels of assistance were tested. Our results reflect that blood flow in the coronary arteries does not correlate with changes in pump flow of rotary blood pumps. The changes in the pulmonary artery could reflect a drop in pulmonary vascular resistance: an effect that eventually may contribute in significant measure to the stabilization of the right ventricle. A change in the geometry of the left ventricle due to the unloading may be an alternative explanation. Particularly this unaltered coronary perfusion at falling oxygen consumption might contribute to cardiac recovery. The second project refers to endocardial suction that can occur with rotary pumps as well as with pulsatile pumps, leading to possible ventricular collapse, suction of the ventricular wall and subsequent right ventricular dysfunction. We report severe ventricular arrhythmias closely related to suction events in rotary blood pumps, a phenomenon that has not been described before. Our aim was to find arrhythmias related to suction and classify them either as monomorphic ventricular tachycardia (single beat), monomorphic ventricular tachycardia (series) or as polymorphic ventricular tachycardia. 19 patients underwent an overall number of 57 measurement sessions. The electrocardiagramms were classified semi-manually aided be a graphical user interface. It was observed that excessive ventricular unloading of the left ventricle during continuous left ventricular support can induce ventricular arrhythmias; there is also an evidence for an increase of arrhythmic activity after suction. This turned out to be a transient effect, which vanishes within five minutes after suction. The ECG-events related to suction have a sudden onset and are severe ventricular arrhythmias, which can consist of even just one extrasystolic beat and they usually cease after clearance of suction. We conclude that suction events in rotary blood pumps can cause severe ventricular arrhythmias and need to be avoided. Whether these post-LVAD ventricular arrhythmias are associated with an adverse outcome needs to be investigated further.eingereicht von Peter VoitlWien, Med. Univ., Diss., 2008OeBB(VLID)171354

Risk of infection in the first year of life in preterm children: An Austrian observational study.

Newborns, especially preterm infants, have an immature immune system, which, in combination with the required medical interventions necessary for keeping the neonate alive may lead to an increased risk of infection. Even after reaching stability and adapting to the environment, preterm infants have adverse prognoses regarding infections and long-term outcomes compared to their full-term counterparts. The objective of this study was to research differences in the number and severity of infections between preterm and full-term infants during their first year of life. To answer this question, a monocentric prospective study was conducted in a pediatric practice in Vienna, including 71 full-term infants and 72 preterm infants who were observed during their first year of life regarding occurring infections. In respective samples, there was a significantly higher total number of infections in preterm (mean 6.01 ± 3.90) compared to full-term infants (3.85 ± 1.72) during the observation period of one year. Particularly the count of respiratory and severe infections was considerably higher in preterm infants. Otorhinolaryngeal infections were the most frequent of all types of infections in both groups. The pregnancy period, number of siblings, and length of the postnatal hospital stay, were observed as significantly influencing factors which affected the total number of infections. The group of early term infants (37+0 weeks to 38+6) was not significantly different to late term babies (>39+0). The acquired knowledge about the increased risk of infections should lead to a more extensive care for preterm infants, with the objective of reducing the rates of complications, morbidity and mortality in this vulnerable age group in the future

Overweight in children and its perception by parents: cross-sectional observation in a general pediatric outpatient clinic

Abstract Background Childhood overweight is a growing problem in industrialized countries. Parents play a major role in the development and the treatment of overweight in their children. A key factor here is the perception of their child’s weight status. As we know of other studies, parental perception of children’s weight status is very poor. This study aimed to determine factors associated with childhood overweight and parental misperception of weight status. The height and weight of children, as reported by parents were compared with measured data. Methods The study was conducted at a general pediatric outpatient clinic in Vienna, Austria. A total of 600 children (aged 0–14 years) participated in the study. Collection of data was performed by means of a questionnaire comprising items relating to parental weight and social demographics. The parents were also asked to indicate their children’s weight and height, as well as the estimated weight status. Children were weighed and measured and BMI was calculated, allowing a comparison of estimated values and weight categories with the measured data. Results Parental BMI, parental weight and a higher birth weight were identified as factors associated with childhood overweight. No association with the parents’ educational status or citizenship could be proven. We compared parents’ estimations of weight and height of their children with measured data. Here we found, that parental estimated values often differ from measured data. Using only parental estimated data to define weight status leads to misclassifications. It could be seen that parents of overweight children tend to underestimate the weight status of their children, compared to parents of children with normal weight. Conclusions Pediatricians should bear in mind that parental assessment often differs from the measured weight of their children. Hence children should be weighed and measured regularly to prevent them from becoming overweight. This is of particular importance in children with higher birth weight and children of overweight parents. Trial registration Study was not registered. The study was approved by the Ethic committee of the city of Vienna. (EK 13–146-VK)

Noise levels in general pediatric facilities: A health risk for the staff?

This study was initiated to investigate noise levels in general pediatric facilities. Although occupational noise limits of 85dBA for LAeq,8h (daily noise exposure) and 140dBC for LCpeak (peak sound level) have proven to prevent hearing loss, even low levels of continuous noise (45dBA and above) can cause adverse health effects (ISO = International Organization for Standardization, A = Austrian VOLV). The sound level measurements of LAeq (equivalent sound level) and LCpeak were conducted with a decibel meter in the examination rooms (EXR) and waiting rooms (WR) of 10 general pediatric practices and outpatient clinics in the city of Vienna, Austria. LAeq,8h was calculated from LAeq, and independent variables with a potential influence on noise levels were also examined. In EXR, the random sample consisted of 5 to 11 measuring periods per facility (mean: 7.1 ± 1.9) with a total duration between 43.85 and 98.45 min. (total: 10:19:04). With LAeq ranging from 67.2 to 80.2dBA, specific recommended limits were exceeded considerably (ISO: 45dBA; A: 50dBA). In WR, the random sample comprised 5 to 18 measurements per facility (mean: 13.7 ± 5.0) with a total duration ranging from 25 to 90 min. (total: 11:25:00). The values for LAeq were between 60.6dBA and 67.0dBA. All of these significantly exceeded recommended limits of 55dBA (ISO) and 5 out of 10 exceeded 65dBA (A). LCpeak reached 116.1dBC in WR and 114.1dBC in EXR. The highest calculated daily noise exposure of pediatricians (LAeq,8h) was 79dBA. Although no significantly increased risk for hearing loss can be concluded from our findings, it must be assumed that noise levels in general pediatrics have the potential to cause stress and associated health issues. Further research is necessary to foster the recognition of noise-related health impairments of pediatric staff as occupational diseases

Respiratory Infections in Children During a Covid-19 Pandemic Winter

BACKGROUND: The Covid-19 pandemic compelled the implementation of measures to curb the SARS CoV-2 spread, such as social distancing, wearing FFP2 masks, and frequent hand hygiene. One anticipated ramification of these measures was the containment of other pathogens. This prospective, longitudinal study aimed to investigate the spread of 22 common seasonal non-SARS-CoV-2 pathogens, such as RSV and influenza, among children with an acute respiratory infection during a pandemic. METHODS: Three hundred ninety children (0-24 months) admitted to Vienna's largest pediatric center with acute respiratory infection (November 2020-April 2021) were included in this study. The researchers tested nasal swabs for 22 respiratory pathogens by Multiplex PCR, documented clinical features and treatment, and evaluated data for a potential connection with the lockdown measures then in force. RESULTS: The 448 smears revealed the most common pathogens to be rhino-/enterovirus (41.4%), adenovirus (2.2%), and coronavirus NL63 (13.6%). While the first two were active throughout the entire season, coronaviruses peaked in the first trimester of 2021 in conjunction with the lift of the lockdown period (OR 4.371, 95%CI 2.34-8.136, P < 0.001). RSV, metapneumovirus, and influenza were absent. CONCLUSION: This prospective, longitudinal study shows that Covid-19 measures suppressed the seasonal activity of influenza, RSV, and metapneumovirus among very young children, but not of rhino-/enterovirus and adenovirus. The 0-24 month-olds are considered the lowest risk group and were only indirectly affected by the public health measures. Lockdowns were negatively associated with coronaviruses infections

Ultrasound of the infant hip: manual fixation is equivalent to Graf’s technique regarding image quality—a randomized trial

Abstract Background In Middle Europe ultrasonography is the standard method used to screen for developmental dysplasia of the hip in infants. Our aim was to determine whether manual fixation of the child is equivalent to Graf’s technique regarding image quality. Methods This randomized trial was conducted at a free-standing general pediatric outpatient clinic in Vienna, Austria. Healthy infants in the 1st and between the 6th and 8th week of life with no hip malalignment were included. After randomization, Group 1 was examined using Graf’s fixation device and participants in Group 2 were fixated on the examination couch by their parents. In a second step, all images underwent a blinded evaluation. Results A total of 117 babies (Group 1: n = 62, Group 2: n = 54, excluded: n = 1) were examined and 230 images (Group 1: n = 122, Group 2: n = 108) were evaluated, of which 225 were sonographically normal. Two images, showing a type IIa right hip and a type IIa + left hip respectively, were excluded. One participant had to be excluded as the respective images showed two pathologic hip joints. Two images in Group 1 and three in Group 2 were not evaluable. No statistical association between image quality (11 quality criteria and overall evaluability) and fixation technique (0.12 ≤ p ≤ 1.0 or constant) was found. Conclusions Considering sonographically normal hip joints, we found no evidence that manual fixation differed from Graf’s technique regarding image quality. In future studies, hip pathologies should be included and discomfort of infants and parents during the examination should be addressed. Trial registration German Clinical Trials Register, ID: DRKS00015694), registered retrospectively on October 7th, 2018

Additional file 1: of Overweight in children and its perception by parents: cross-sectional observation in a general pediatric outpatient clinic

Questionnaire. (DOCX 72 kb

Second Victims among Austrian Pediatricians (SeViD-A1 Study)

(1) Background: The second victim phenomenon (SVP) plays a critical role in workplace and patient safety. So far, there are limited epidemiological data on the SVP in German-speaking countries. Some studies have been carried out in Germany, but so far, no quantitative studies have been carried out in Austria examining the prevalence, symptom load and preferred support measures for second victims (SVs). This study therefore examines the SVP among Austrian pediatricians. (2) Methods: A nationwide, cross-sectional and anonymous online study was conducted using the SeViD questionnaire (Second Victims in Deutschland) including the Big Five Inventory-10 (BFI-10). Statistical analysis included binary-logistic and multiple linear regression with the bootstrapping, bias-corrected and accelerated (BCa) method based on 1000 bootstrap samples. (3) Results: Of 414 Austrian pediatricians, 89% self-identified as SVs. The main cause of becoming an SV was the unexpected death or suicide of a patient. High neuroticism and extraversion values as well as working in outpatient care positively correlated with having experienced the SVP. A preferred support strategy was access to legal counseling. (4) Conclusions: Austrian pediatricians have the highest SVP prevalence measured with the SeViD questionnaire. Further research should focus on prevention strategies and intervention programs

Supplementarytables_The surge of RSV and other respiratory viruses among children during the second COVID-19 pandemic winter season.docx

BackgroundThe non-pharmaceutical measures in the first Covid-19 winter season significantly impacted respiratory pathogens such as RSV, influenza, or metapneumovirus, which cause respiratory infections, especially in infants and young children. This longitudinal prospective study aimed to determine how less strict measures affect the pathogen profile in the second winter season.MethodsFrom September 2021 till the end of March 2022, 678 children (0–36 months) admitted to Vienna's largest pediatric center with an acute respiratory infection were enrolled in this study. The researchers performed nasal swabs and tested them by multiplex PCR for 23 respiratory pathogens, chronicled clinical features and treatment, and analyzed the effect of lockdown on the pathogen prevalence.ResultsThe 815 smears of 678 children revealed the most common pathogens to be rhino-/enterovirus (38.5%), RSV (26.7%), and metapneumovirus (7.2%). The lockdown interrupted the early RSV onset in September [RR 0.367, CI (0.184–0.767), p = 0.003], while no effects on the other pathogens were found. Metapneumovirus started circulating in January. Influenza was only sporadically detected. The hospitalization rate was significantly higher than last season due to RSV [OR 4.089, 95%CI (1.414–11.827), p-adj = 0.05].ConclusionWith more flexible non-pharmaceutical measures, children aged 0–36 months started presenting again with viral pathogens, such as RSV and metapneumovirus. RSV, associated with a high hospitalization rate, had a very early onset with an abrupt interruption due to the only lockdown.</p