European journal of anaesthesiology
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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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Mathematical coupling may explain in part why cardiac filling volumes obtained by transpulmonary thermodilution may better predict and monitor responses of cardiac output to fluid loading than pressures obtained by pulmonary artery catheters (PACs). ⋯ After coronary surgery, fluid responses can be similarly assessed by intermittent transpulmonary and continuous pulmonary thermodilution methods, in spite of overestimation of CCIp by CItp. Filling pressures are poor monitors of fluid responses and superiority of GEDVI can be caused, at least in part, by mathematical coupling when cardiac volume and output are derived from the same thermodilution curve.
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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.
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We sought to test whether a transient myocardial ischaemia can induce impairment of hippocampal long-term potentiation (LTP) and whether sevoflurane preconditioning can provide robust protective effects on this neurological impairment. ⋯ Sevoflurane preconditioning induced neuroprotection against impairment of hippocampal LTP resulting from myocardial ischaemia and reperfusion.
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Letter Case Reports
Cranial nerve injuries from a laryngeal mask airway.