Effect of Head Rotation on Cerebral Blood Velocity in the Prone Position

Background. The prone position is applied to facilitate surgery of the back and to improve oxygenation in the respirator-treated patient. In particular, with positive pressure ventilation the prone position reduces venous return to the heart and in turn cardiac output (CO) with consequences for cerebral blood flow. We tested in healthy subjects the hypothesis that rotating the head in the prone position reduces cerebral blood flow. Methods. Mean arterial blood pressure (MAP), stroke volume (SV), and CO were determined, together with the middle cerebral artery mean blood velocity (MCA Vmean) and jugular vein diameters bilaterally in 22 healthy subjects in the prone position with the head centered, respectively, rotated sideways, with and without positive pressure breathing (10 cmH2O). Results. The prone position reduced SV (by 5.4±1.5%; P<0.05) and CO (by 2.3±1.9 %), and slightly increased MAP (from 78±3 to 80±2 mmHg) as well as bilateral jugular vein diameters, leaving MCA Vmean unchanged. Positive pressure breathing in the prone position increased MAP (by 3.6±0.8 mmHg) but further reduced SV and CO (by 9.3±1.3 % and 7.2±2.4 % below baseline) while MCA Vmean was maintained. The head-rotated prone position with positive pressure breathing augmented MAP further (87±2 mmHg) but not CO, narrowed both jugular vein diameters, and reduced MCA Vmean (by 8.6±3.2 %). Conclusion. During positive pressure breathing the prone position with sideways rotated head reduces MCA Vmean ~10% in spite of an elevated MAP. Prone positioning with rotated head affects both CBF and cerebrovenous drainage indicating that optimal brain perfusion requires head centering

The Procalcitonin And Survival Study (PASS) – A Randomised multi-center investigator-initiated trial to investigate whether daily measurements biomarker <it>Procalcitonin </it>and pro-active diagnostic and therapeutic responses to abnormal Procalcitonin levels, can improve survival in intensive care unit patients. Calculated sample size (target population): 1000 patients

<p>Abstract</p> <p>Background</p> <p>Sepsis and complications to sepsis are major causes of mortality in critically ill patients. Rapid treatment of sepsis is of crucial importance for survival of patients. The infectious status of the critically ill patient is often difficult to assess because symptoms cannot be expressed and signs may present atypically. The established biological markers of inflammation (leucocytes, C-reactive protein) may often be influenced by other parameters than infection, and may be unacceptably slowly released after progression of an infection. At the same time, lack of a relevant antimicrobial therapy in an early course of infection may be fatal for the patient. Specific and rapid markers of bacterial infection have been sought for use in these patients.</p> <p>Methods</p> <p>Multi-centre randomized controlled interventional trial. Powered for superiority and non-inferiority on all measured end points. Complies with, "Good Clinical Practice" (ICH-GCP Guideline (CPMP/ICH/135/95, Directive 2001/20/EC)). Inclusion: 1) Age ≥ 18 years of age, 2) Admitted to the participating intensive care units, 3) Signed written informed consent.</p> <p>Exclusion: 1) Known hyper-bilirubinaemia. or hypertriglyceridaemia, 2) Likely that safety is compromised by blood sampling, 3) Pregnant or breast feeding.</p> <p>Computerized Randomisation: Two arms (1:1), n = 500 per arm: Arm 1: standard of care. Arm 2: standard of care and Procalcitonin guided diagnostics and treatment of infection.</p> <p>Primary Trial Objective: To address whether daily Procalcitonin measurements and immediate diagnostic and therapeutic response on day-to-day changes in procalcitonin can reduce the mortality of critically ill patients.</p> <p>Discussion</p> <p>For the first time ever, a mortality-endpoint, large scale randomized controlled trial with a biomarker-guided strategy compared to the best standard of care, is conducted in an Intensive care setting. Results will, with a high statistical power answer the question: Can the survival of critically ill patients be improved by actively using biomarker procalcitonin in the treatment of infections? 700 critically ill patients are currently included of 1000 planned (June 2008). Two interim analyses have been passed without any safety or futility issues, and the third interim analysis is soon to take place. Trial registration number at clinicaltrials.gov: Id. nr.: NCT00271752).</p