European journal of anaesthesiology
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Review
Emerging trends in minimally invasive haemodynamic monitoring and optimization of fluid therapy.
For decades the pulmonary artery catheter has been the mainstay of cardiac output monitoring in critically ill patients, and pressure-based indices of ventricular filling have been used to gauge fluid requirements with acknowledged limitations. In recent years, alternative technologies have become available which are minimally invasive, allow beat-to-beat cardiac output monitoring and permit assessment of fluid requirements by volumetric means and by allowing assessment of heart-lung interaction in mechanically ventilated patients. ⋯ In fully mechanically ventilated patients, dynamic measurements of heart-lung interaction such as stroke volume variation are superior to static measures of preload in assessing whether a patient is volume-responsive (i.e. will increase stroke volume in response to a fluid challenge). For patients who are not fully mechanically ventilated, pulse contour analysis allows real-time assessment of increases in cardiac output in response to passive leg-raising.
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Endoscopic vein harvest (EVH) for coronary artery bypass grafting surgery is performed with carbon dioxide (CO2) insufflation for visualization and dissection. The insufflated CO2 is rapidly absorbed into the body and may influence haemodynamics. However, the haemodynamic changes during EVH have not been clearly defined. This study evaluated the haemodynamic effects during EVH of the saphenous vein for off-pump coronary artery bypass grafting surgery (OPCAB). ⋯ EVH, at a maximum CO2 pressure of 12 mmHg and a flow of 3 l/min, of the saphenous vein for OPCAB was associated with hypercarbia and a tolerable range of hypercarbia (PaCO2 < 60 mmHg) increased the cardiac index and ScO2 without any complications.
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Comparative Study
Influence of temperature on the positive inotropic effect of levosimendan, dobutamine and milrinone.
Patients in cardiac surgery and critically ill patients often demonstrate either hypothermia or fever. In addition, owing to heart failure, they frequently require inotropic support. The relative effectiveness of modern inotropic agents at various temperatures has not yet been evaluated. Therefore, we investigated the influence of levosimendan, dobutamine and milrinone on the contractile response of myocardial trabeculae at various temperatures. ⋯ Our results suggest no modulation of levosimendan-induced inotropy under the experimental temperatures tested. This observation is possibly due to its Ca2+-sensitizing mechanism, which might not be influenced by temperature-related changes in intracellular Ca2+ levels. In contrast, the inotropic effect of cyclic AMP-coupled dobutamine and milrinone is suppressed under hypothermia-related interaction with intracellular Ca2+ homeostasis. Hence, levosimendan might prove to be the preferred inotropic drug in hypothermic patients.
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Percutaneous dilational tracheostomy (PDT) is an accepted method in intensive care patients. In our neurosurgical ICU, we routinely perform PDT. We have performed 130 PDT procedures and have often observed previously reported difficulties/complications: dislocation of the endotracheal tube (ETT); frequent puncture of the ETT cuff; difficult visualization of the entire procedure because the ETT is often in the way; and risk of damaging the posterior tracheal wall due to needle puncture or rotating dilator. We believe that the rate of complications is directly related to the ability and experience of the anaesthetist carrying out the PDT. Because our hospital is a university teaching centre, PDT is often carried out by residents who are not experienced with the technique. In order to guarantee the patient's safety and to optimize the learning curve, we propose, in such circumstances, the use of a modified standard ETT. ⋯ The dedicated ETT eliminates puncturing of the ETT, rupture of the cuff and difficult direct vision. We report an optimal stability of the tube during the whole procedure and improvement in the efficacy and safety of the procedure. When residents attempt PDF for the first time, we believe that it would be safer and more practical to perform such a technique with the dedicated ETT.