Speckle tracking echography allows sonographic assessment of diaphragmatic loading

Introduction: Assessment of diaphragm function should ideally be assessed using magnetic twitch pressure or esophageal and gastric balloons. Conventional sonographic techniques as thickness and fractional thickening (FT), only provide limited insight in diaphragm function. Speckle tracking echocardiography allows reliable quantification of muscle function by tracking of grey patterns and their motion; strain as parameter of muscle deformation and strain rate as deformation velocity. Aim: To investigate whether speckle tracking can quantify loading of the diaphragm, superior to FT. Methods: 13 healthy volunteers underwent an inspiratory loading protocol with recording of transdiaphragmatic pressure (Pdi) and diaphragm electromyography (EMGdi). Inspiratory loading of 0 to 30% of maximal inspiratory pressure was applied in random order for 5 minutes per applied load. Diaphragmatic sonography was performed using a 2-4 MHz linear phased array transducer positioned at the right-lateral thoracic wall in the anterior axillary line longitudinal to the body axis. Ultrasound recordings of the diaphragm were made at the marked location during 10 seconds. Results: Increased inspiratory loading increased Pdi and EMGdi. Sonographic markers of contractility increased with incremental loading. Pdi correlated with strain (r=0.75; p=0.000) and strain rate (r=0.77; p=0.000). Contrarily, FT was not correlated with Pdi. Conclusion: Speckle tracking of the diaphragm can detect changes in diaphragmatic loading up to 30% of maximal inspiratory pressure. It might be a valuable tool to detect changes in loading in specific patient categories, including patients with acute respiratory failure and ventilated ICU patients

Heating capabilities of small fluid warming systems

Abstract Background Perioperative temperature management is fundamental to ensure normothermia in patients. Fluid warmers, which have become smaller in size over the past few years, can help to maintain a stable body temperature. Potentially, the reduction of the size may influence the heating performance. Methods Therefore, we tested the effectiveness of enFlow®, Fluido compact® and Thermosens® fluid warmers by measuring the inlet and outlet temperature for room-tempered and ice-cooled saline at flow rates of 25, 50, 75 and 100 ml/min. Results At all examined flow rates, the tested heating devices warmed up room-tempered saline effectively. The enFlow® provided the significantly (p  38 °C at all tested flow rates. The Fluido compact® ensured this only at flow rates of 25 and 50 ml/min, while the Thermosens® provided these conditions at flow rates of 25, 50 and 75 ml/min. Conclusions The heating capability for room-tempered saline was effective in all tested devices, but with ice-cooled saline enFlow® is superior at high flow rates. At low flow rates the heating capabilities of enFlow®, Fluido compact® and Thermosens® are comparable

Heating capabilities of small fluid warming systems

Abstract Background Perioperative temperature management is fundamental to ensure normothermia in patients. Fluid warmers, which have become smaller in size over the past few years, can help to maintain a stable body temperature. Potentially, the reduction of the size may influence the heating performance. Methods Therefore, we tested the effectiveness of enFlow®, Fluido compact® and Thermosens® fluid warmers by measuring the inlet and outlet temperature for room-tempered and ice-cooled saline at flow rates of 25, 50, 75 and 100 ml/min. Results At all examined flow rates, the tested heating devices warmed up room-tempered saline effectively. The enFlow® provided the significantly (p < 0.05) highest outlet temperature throughout all tested flow rates in comparison to the other devices. When ice-cooled saline was used, the enFlow® maintained a stable outlet temperature > 38 °C at all tested flow rates. The Fluido compact® ensured this only at flow rates of 25 and 50 ml/min, while the Thermosens® provided these conditions at flow rates of 25, 50 and 75 ml/min. Conclusions The heating capability for room-tempered saline was effective in all tested devices, but with ice-cooled saline enFlow® is superior at high flow rates. At low flow rates the heating capabilities of enFlow®, Fluido compact® and Thermosens® are comparable

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

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. This study investigated which weaning method allows more efficient restoration of diaphragm homeostasis.status: publishe

Sevoflurane Exposure Prevents Diaphragmatic Oxidative Stress During Mechanical Ventilation but Reduces Force and Affects Protein Metabolism Even During Spontaneous Breathing in a Rat Model

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. This study has been performed on the hypothesis that sevoflurane might protect against ventilator-induced diaphragmatic dysfunction by preventing the production of oxidative stress.status: publishe

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. The primary aim of this study was to establish a post-mortem rat perfusion model using extracorporeal membrane oxygenation (ECMO) in surplus rat cadavers and generate first post vivo results concerning the oxygenation performance of a recently developed ECMO membrane oxygenator. Four rats were euthanized and connected post-mortem to a venous–arterial ECMO circulation for up to eight hours. Angiographic perfusion proofs, blood gas analyses and blood oxygenation calculations were performed. The mean preparation time for the ECMO system was 791 ± 29 s and sufficient organ perfusion could be maintained for 463 ± 26 min, proofed via angiographic imaging and a mean femoral arterial pressure of 43 ± 17 mmHg. A stable partial oxygen pressure, a 73% rise in arterial oxygen concentration and an exponentially increasing oxygen extraction ratio up to 4.75 times were shown. Considering the 3Rs, the established post-mortal ECMO perfusion rat model using surplus animals represents a promising alternative to models using live animals. Given the preserved organ perfusion, its use could be conceivable for various biomedical device testing

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

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. Clinical data imply a correlation between cumulative propofol dosage and diaphragm dysfunction, whereas laboratory investigations have revealed that propofol has some antioxidant properties. The authors hypothesized that propofol reduces markers of oxidative stress, atrophy, and contractile dysfunction in the diaphragm.status: publishe

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

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.status: publishe