Hammash: Cardiac Rhythm during Mechaincial Ventilation and Weaning from Ventilation

Background: Cardiac dysrhythmias during weaning and its subsequent impact on weaning outcome have received little attention. Purpose: To 1) evaluate the impact of changes in intrathoracic vascular volume and autonomic nervous system (ANS) tone during weaning on dysrhythmias development and 2) determine the impact of dysrhythmias on cardiac index, myocardial ischemia and weaning outcome. The specific aims are To determine: 1) the effect intrathoracic vascular volume on dysrhythmias development; 2) the effect of ANS tone on dysrhythmias development; 3) whether cardiac index or myocardial ischemia mediate the relationship between dysrhythmias and weaning outcome; and 4) the effect of occurrence of dysrhythmias on weaning outcome. Method: sixty patients >= 18 years old and ventilated at least for 24hrs will be included in a descriptive, comparative, repeated measures study. Patients having recent myocardial infarction, neurological trauma, chronic atrial fibrillation, and a pacemaker will be excluded. Using a Holter monitor and Bio-z device, cardiac rhythm and hemodynamic measures will be evaluated respectively at baseline during mechanical ventilation, 1hour before and during the initial weaning trial. Demographic and clinical data will be collected from patients' medical records. Implications: This study will provide important information about cardiac dysrhythmias and its impact on weaning outcome.