Post-Mortem Extracorporeal Membrane Oxygenation Perfusion Rat Model: A Feasibility Study.

The development of biomedical soft- or hardware frequently includes testing in animals. However, large efforts have been made to reduce the number of animal experiments, according to the 3Rs principle. Simultaneously, a significant number of surplus animals are euthanized without scientific necessity.

Speckle tracking ultrasonography as a new tool to assess diaphragmatic function: a feasibility study.

A reliable method of measuring diaphragmatic function at the bedside is still lacking. Widely used two-dimensional (2D) ultrasonographic measurements, such as diaphragm excursion, diaphragm thickness, and fractional thickening (FT) have failed to show clear correlations with diaphragmatic function. A reason for this is that 2D ultrasonographic measurements, like FT, are merely able to measure the deformation of muscular diaphragmatic tissue in the transverse direction, while longitudinal measurements in the direction of contracting muscle fibres are not possible.

Effects of elevated positive end-expiratory pressure on diaphragmatic blood flow and vascular resistance during mechanical ventilation.

Although mechanical ventilation (MV) is a life-saving intervention, prolonged MV can lead to deleterious effects on diaphragm function, including vascular incompetence and weaning failure. During MV, positive end-expiratory pressure (PEEP) is used to maintain small airway patency and mitigate alveolar damage. We tested the hypothesis that increased intrathoracic pressure with high levels of PEEP would increase diaphragm vascular resistance and decrease perfusion.

Impaired diaphragm resistance vessel vasodilation with prolonged mechanical ventilation.

Mechanical ventilation (MV) is a life-saving intervention, yet with prolonged MV (i.e., ≥6 h) there are time-dependent reductions in diaphragm blood flow and an impaired hyperemic response of unknown origin.

Effect of Long-Term Polytrauma on Ventilator-Induced Diaphragmatic Dysfunction in a Piglet Model.

Introduction: Mechanical ventilation is known to activate oxidative stress and proteolytic pathways in the diaphragm. Trauma by inducing inflammation and activating proteolytic pathways may potentiate the effects of mechanical ventilation on the diaphragm. In a blunt chest trauma with concomitant injuries we tested the hypothesis that trauma via inflammation further activates the proteolytic pathways and worsens atrophy in the diaphragm.

Dexmedetomidine Impairs Diaphragm Function and Increases Oxidative Stress but Does Not Aggravate Diaphragmatic Atrophy in Mechanically Ventilated Rats.

Background: Anesthetics in ventilated patients are critical as any cofactor hampering diaphragmatic function may have a negative impact on the weaning progress and therefore on patients' mortality. Dexmedetomidine may display antioxidant and antiproteolytic properties, but it also reduced glucose uptake by the muscle, which may impair diaphragm force production. This study tested the hypothesis that dexmedetomidine could inhibit ventilator-induced diaphragmatic dysfunction.

Acceleration sensors in abdominal wall position as a non-invasive approach to detect early breathing alterations induced by intolerance of increased airway resistance.

Background: Early detection of respiratory overload is crucial to mechanically ventilated patients, especially during phases of spontaneous breathing. Although a diversity of methods and indices has been established, there is no highly specific approach to predict respiratory failure. This study aimed to evaluate acceleration sensors in abdominal and thoracic wall positions to detect alterations in breathing excursions in a setting of gradual increasing airway resistance.

Functional assessment of the diaphragm by speckle tracking ultrasound during inspiratory loading.

Assessment of diaphragmatic effort is challenging, especially in critically ill patients in the phase of weaning. Fractional thickening during inspiration assessed by ultrasound has been used to estimate diaphragm effort. It is unknown whether more sophisticated ultrasound techniques such as speckle tracking are superior in the quantification of inspiratory effort.

Kinetics of ventilation-induced changes in diaphragmatic metabolism by bilateral phrenic pacing in a piglet model.

Perioperative necessity of deep sedation is inevitably associated with diaphragmatic inactivation. This study investigated 1) the feasibility of a new phrenic nerve stimulation method allowing early diaphragmatic activation even in deep sedation and, 2) metabolic changes within the diaphragm during mechanical ventilation compared to artificial activity. 12 piglets were separated into 2 groups.

Influence of weaning methods on the diaphragm after mechanical ventilation in a rat model.

Background: Mechanical ventilation (MV) is associated with diaphragm weakness, a phenomenon termed ventilator-induced diaphragmatic dysfunction. Weaning should balance diaphragmatic loading as well as prevention of overload after MV. The weaning methods pressure support ventilation (PSV) and spontaneous breathing trials (SBT) lead to gradual or intermittent reloading of a weak diaphragm, respectively.

Xenon triggers pro-inflammatory effects and suppresses the anti-inflammatory response compared to sevoflurane in patients undergoing cardiac surgery.

Introduction: Cardiac surgery encompasses various stimuli that trigger pro-inflammatory mediators, reactive oxygen species and mobilization of leucocytes. The aim of this study was to evaluate the effect of xenon on the inflammatory response during cardiac surgery.

Methods: This randomized trial enrolled 30 patients who underwent elective on-pump coronary-artery bypass grafting in balanced anaesthesia of either xenon or sevoflurane.

Sevoflurane exposure prevents diaphragmatic oxidative stress during mechanical ventilation but reduces force and affects protein metabolism even during spontaneous breathing in a rat model.

Background: Ventilator-induced diaphragmatic dysfunction is associated with the generation of oxidative stress, enhanced proteolysis, autophagy and reduced protein synthesis in the diaphragm. Sevoflurane is a common operating room anesthetic and can be used in the intensive care medicine as well. Besides its anesthetic properties, its use in cardiac ischemia-reperfusion models can maintain protein synthesis and inhibit generation of reactive oxygen species, if used at the beginning of heart surgery.

Recovery of diaphragm function following mechanical ventilation in a rodent model.

Background: Mechanical ventilation (MV) induces diaphragmatic muscle fiber atrophy and contractile dysfunction (ventilator induced diaphragmatic dysfunction, VIDD). It is unknown how rapidly diaphragm muscle recovers from VIDD once spontaneous breathing is restored. We hypothesized that following extubation, the return to voluntary breathing would restore diaphragm muscle fiber size and contractile function using an established rodent model.

Sedation using propofol induces similar diaphragm dysfunction and atrophy during spontaneous breathing and mechanical ventilation in rats.

Background: Mechanical ventilation is crucial for patients with respiratory failure. The mechanical takeover of diaphragm function leads to diaphragm dysfunction and atrophy (ventilator-induced diaphragmatic dysfunction), with an increase in oxidative stress as a major contributor. In most patients, a sedative regimen has to be initiated to allow tube tolerance and ventilator synchrony.

Prolonged mechanical ventilation alters the expression pattern of angio-neogenetic factors in a pre-clinical rat model.

Objective: Mechanical ventilation (MV) is a life saving intervention for patients with respiratory failure. Even after 6 hours of MV, diaphragm atrophy and dysfunction (collectively referred to as ventilator-induced diaphragmatic dysfunction, VIDD) occurs in concert with a blunted blood flow and oxygen delivery. The regulation of hypoxia sensitive factors (i.

Negative pressure ventilation and positive pressure ventilation promote comparable levels of ventilator-induced diaphragmatic dysfunction in rats.

Background: Mechanical ventilation is a life-saving intervention for patients with respiratory failure. Unfortunately, a major complication associated with prolonged mechanical ventilation is ventilator-induced diaphragmatic atrophy and contractile dysfunction, termed ventilator-induced diaphragmatic dysfunction (VIDD). Emerging evidence suggests that positive pressure ventilation (PPV) promotes lung damage (ventilator-induced lung injury [VILI]), resulting in the release of signaling molecules that foster atrophic signaling in the diaphragm and the resultant VIDD.

Accuracy of the Masimo Pronto-7® system in patients with left ventricular assist device.

Background: The Masimo Pronto-7® calculates hemoglobin (Hb) values using the pulsoximetry technique and a variety of mathematical algorithms analyzing the pulse waveform. Although this system has demonstrated a high level of accuracy in average patients, the performance might be altered in special patient populations. Regarding patients with left ventricular cardiac failure, a rotary blood pump generates a constant, continuous, non-pulsatile flow to improve effective cardiac output.

Xenon consumption during general surgery: a retrospective observational study.

Background: High costs still limits the widespread use of xenon in the clinical practice. Therefore, we evaluated xenon consumption of different delivery modes during general surgery.

Methods: A total of 48 patients that underwent general surgery with balanced xenon anaesthesia were retrospectively analysed according to the mode of xenon delivery during maintenance phase (ECO mode, AUTO mode or MANUAL mode).

What is the significance of perioperative release of macrophage migration inhibitory factor in cardiac surgery?

Cardiac surgery is associated with release of the pleiotropic cytokine macrophage migration inhibitory factor (MIF). The trigger for MIF release has not yet been elucidated. Owing to its intrinsic antioxidative activity, MIF might reduce oxidative stress and protect from myocardial ischemia and reperfusion (I/R) injury.

Mechanical ventilation reduces rat diaphragm blood flow and impairs oxygen delivery and uptake.

Objectives: Although mechanical ventilation is a life-saving intervention in patients suffering from respiratory failure, prolonged mechanical ventilation is often associated with numerous complications including problematic weaning. In contracting skeletal muscle, inadequate oxygen supply can limit oxidative phosphorylation resulting in muscular fatigue. However, whether prolonged mechanical ventilation results in decreased diaphragmatic blood flow and induces an oxygen supply-demand imbalance in the diaphragm remains unknown.

Both high level pressure support ventilation and controlled mechanical ventilation induce diaphragm dysfunction and atrophy.

Objectives: Previous workers have demonstrated that controlled mechanical ventilation results in diaphragm inactivity and elicits a rapid development of diaphragm weakness as a result of both contractile dysfunction and fiber atrophy. Limited data exist regarding the impact of pressure support ventilation, a commonly used mode of mechanical ventilation-that permits partial mechanical activity of the diaphragm-on diaphragm structure and function. We carried out the present study to test the hypothesis that high-level pressure support ventilation decreases the diaphragm pathology associated with CMV.

Physiology of gas exchange during anaesthesia.

Mechanical ventilation is a prerequisite for many surgical interventions. Furthermore, during states of severe gas exchange disturbance or impaired neurological conditions with the threat of aspiration or cardiovascular instability, it is a life-saving intervention on every ICU. Even the induction of anaesthesia disturbs the physiological lung function, due to changes in chest wall mechanics and diaphragm relaxation, generating atelectases, gas exchange disturbance and ventilation-perfusion mismatch.

Effects of aging and exercise training on spinotrapezius muscle microvascular PO2 dynamics and vasomotor control.

With advancing age, there is a reduction in exercise tolerance, resulting, in part, from a perturbed ability to match O(2) delivery to uptake within skeletal muscle. In the spinotrapezius muscle (which is not recruited during incline treadmill running) of aged rats, we tested the hypotheses that exercise training will 1) improve the matching of O(2) delivery to O(2) uptake, evidenced through improved microvascular Po(2) (Pm(O(2))), at rest and throughout the contractions transient; and 2) enhance endothelium-dependent vasodilation in first-order arterioles. Young (Y, ∼6 mo) and aged (O, >24 mo) Fischer 344 rats were assigned to control sedentary (YSED; n = 16, and OSED; n = 15) or exercise-trained (YET; n = 14, and OET; n = 13) groups.