254 research outputs found

    Improving newborn respiratory outcomes with a sustained inflation: a systematic narrative review of factors regulating outcome in animal and clinical studies

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    Respiratory support is critically important for survival of newborns who fail to breathe spontaneously at birth. Although there is no internationally accepted definition of a sustained inflation (SI), it has commonly been defined as a positive pressure inflation designed to establish functional residual capacity and applied over a longer time period than normally used in standard respiratory support (SRS). Outcomes vary distinctly between studies and to date there has been no comprehensive investigation of differences in SI approach and study outcome in both pre-clinical and clinical studies. A systematic literature search was performed and, after screening, identified 17 animal studies and 17 clinical studies evaluating use of a SI in newborns compared to SRS during neonatal resuscitation. Study demographics including gestational age, SI parameters (length, repetitions, pressure, method of delivery) and study outcomes were compared. Animal studies provide mechanistic understanding of a SI on the physiology underpinning the cardiorespiratory transition at birth. In clinical studies, there is considerable difference in study quality, delivery of SIs (number, pressure, length) and timing of primary outcome evaluation which limits direct comparison between studies. The largest difference is method of delivery, where the role of a SI has been observed in intubated animals, as the inflation pressure is directly applied to the lung, bypassing the obstructed upper airway in an apnoeic state. This highlights a potential limitation in clinical use of a SI applied non-invasively. Further research is required to identify if a SI may have greater benefits in subpopulations of newborns.Developmen

    Elektrochemische Potentiale während Hochfrequenz-Katheterablation von Herzrhythmusstörungen : In vitro und in vivo Experimente und erste klinische Erfahrungen

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    Einleitung: Die temperaturkontrollierte Katheterablation besitzt eine Reihe von Limitationen wie u.a. moderate Korrelation mit der Gewebetemperatur und Läsionsentwicklung. Ziel der vorliegenden Arbeit war es, ein Steuerungsparameter zu entwickeln, der die Qualität des Elektrodenkontaktes mit dem Gewebe und das Wachstum der Koagulationsnekrose direkt anhand zellulärer bzw. biologischer Prozesse des Zielgewebes wiedergibt. Material und Methodik: Endomyokard-Präparate frisch geschlachteter Rinder wurden in einem Tankbad mit physiologischer Kochsalzlösung für die in vitro Experimente verwandt, wo bei das elektrochemische Potential (eP) wie bei allen Untersuchungen zwischen der distalen und der proximalen Elektrode abgeleitet wurde. Tierexperimente wurden bei 8 intubiert, beatmeten Schweinen durchgeführt, wobei der experimentelle Aufbau adäquat zu den Bedingungen in vitro- elektrochemisches Potential zwischen distaler und proximaler Elektrode - war. Die ersten klinischen Untersuchungen wurden an 50 konsekutiven Patienten (m/w 29:21; 49,7 ± 9,8 Jahre), die zur elektiven Katheter-Ablation von supraventrikulären Tachykardien AVNRT bzw. WPW-Syndrom eingewiesen wurden, durchgeführt. Der meßtechnische Aufbau war unverändert zu den in vitro bzw. Tierexperimenten. Ergebnisse: Der Nachweis von eP gelang sowohl invitro, tierexperimentell als auch im klinischen Teil der Arbeit. Ferner konnte eine hohe Korrelation des elektrochemischen Potentials mit dem bisher üblichen Parameter \u27Temperatur\u27 errechnet werden (r=0,87). Eine ebenfalls hohe Korrelation wurde zwischen der Läsionsentwicklung und den eP festgestellt: r=0,85; p<0,001. Auch bei den \u27Routine-Kateterablationen\u27 konnte die Messung der eP bei Patienten durchgeführt werden. Ferner konnte mittels eP-gesteuerter Energieabgabe die Durchführbarkeit einer Katheterablation mit dem Parameters \u27eP\u27 gezeigt werden. Diskussion: Der Ursprung des eP liegt in der Läsionsentwicklung durch Erhitzung des myokardialen Gewebes. Die elektromotorische Kraftquelle des eP ist die Diffusion von freien Radikalen und intrazellulären Elektrolyten aus der Koagulationsläsion. Die eP stellt einen zusätzlichen Parameter neben der Temperatur und Impedanz - mit besserer Korrelation zur Läsion- dar. Die Steuerung der HF-Strom-Energieabgabe durch die eP ist möglich und erlaubt den Einsatz thermosensorfreier Elektroden. Potentiell klinische Anwendungen stellen die gekühlte Ablation sowie der Einsatz von multipolaren Ablationskathetern dar.Introduction: Temperature controlled radiofrequency catheter ablation (TRF) is widely introduced in current clinical practice with several limitations as the moderate correlation between catheter tip temperature (CTT) and lesion size (LS), and the increase in stiffness of multielectrode thermosensor catheters for the creation of linear lesions. Thermal injury of subendocardial tissue leads to a release of electrolytes and free radicals from the intracellular site creating a change in potential (dP) between distal and proximal catheter tip electrode. The aim of the doctorate was to verify the detection of ablation-induced release of electrolytes and free radicals and the possibility to control energy delivery in ablation by measuring dP. Energieabgabe die Durchführbarkeit einer Katheterablation mit dem Parameters \u27eP\u27 gezeigt werden. Methods and Results: In vitro tests at constant flow condition were performed in a 10 l bath of physiological saline solution and cattle blood. Endomyocardial preparations of fresh cattle hearts were used. Closed-loop temperature-controlled and closed-loop dP-controlled ablations were performed. In vivo animal investigations were performed in anesthetized and ventilated pigs. The existence of the dP was established in the tank model and was confirmed in the animal investigations. Good correlations were found between dP and CTT (r=0.87) and between maximum dP and induced LS (r=0.85). A high correlation (r=0.85, p<0.001) was found between dP and lesion volume. During routinely catheter ablation in 50 patients with supraventicular tachycardia dP-measurement was performed. Energieabgabe die Durchführbarkeit einer Katheterablation mit dem Parameters \u27eP\u27 gezeigt werden. Conclusions: Control of energy delivery during RF-ablation by the measurement of dP is feasible. In comparison to TRF, ablation steered by dP-measurement revealed superior correlation to induced LS. During irrigated catheter ablation, dP measurement is the only tool for energy control. To our knowledge, this is the first report on this novel method of ablation control

    Hypothermia during umbilical catheterization in preterm infants

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    Objective: To describe the effect of umbilical catheterization (UC) on skin temperature and cardiorespiratory status in preterm infants.Materials and methods: In a prospective observational study of infants <32 weeks of gestation, the duration of UC, course of skin temperature, and cardiorespiratory status were registered. Hypothermia was defined as a temperature below 36.5C.Results: UC was performed in 55 infants with a median (range) gestational age of 28 weeks (24-31) and birth weight of 1120g (625-2091). Mean (SD) temperature first decreased 0.6 (0.6)degrees C during UC followed by a rise of 0.4 (0.4)degrees C after reaching the minimal temperature. Hypothermia already existed in 69% (38/55) of the infants before start of UC, which increased to 89% (49/55) during UC (p = .001). Duration of UC was not associated with the development of hypothermia during the procedure (p = .48). Heart rate (mean(SD)) significantly increased (162 (17) versus 152 (15); p <.001) and there was a trend toward an increase in supplemental oxygen (mean(SD)) (0.31 (0.17) versus 0.28 (0.13); p = .78), but both changes were only temporary.Conclusion: Hypothermia was frequent in preterm infants before start of UC and increased during UC. Postponing UC until the infant has a normal temperature should be considered.Developmen

    The effect of breathing on ductus arteriosus blood flow directly after birth

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    Research into fetal development and medicin

    Clinical aspects of incorporating cord clamping into stabilisation of preterm infants

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    Fetal to neonatal transition is characterised by major pulmonary and haemodynamic changes occurring in a short period of time. In the international neonatal resuscitation guidelines, comprehensive recommendations are available on supporting pulmonary transition and delaying clamping of the cord in preterm infants. Recent experimental studies demonstrated that the pulmonary and haemodynamic transition are intimately linked, could influence each other and that the timing of umbilical cord clamping should be incorporated into the respiratory stabilisation. We reviewed the current knowledge on how to incorporate cord clamping into stabilisation of preterm infants and the physiological-based cord clamping (PBCC) approach, with the infant's transitional status as key determinant of timing of cord clamping. This approach could result in optimal timing of cord clamping and has the potential to reduce major morbidities and mortality in preterm infants
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