Introduction : Weaning trials are performed to assess the readiness of mechanically ventilated patients to sustain spontaneous ventilation. Spontaneous breathing increases ba­sal metabolism and weaning increas­es cardiopulmonary demand. The most critical time for patients with chronic obstructive pulmonary dis­ease (COPD) mechanically ventilated for acute respiratory failure is the weaning period . Myocardial ischemia is potentially the most important cause of reduced contractility during weaning. This myocardia! ischemia might occur as a consequence either of a reduction in myocardial oxygen supply or of an increase in myocardial oxygen demand or both. A reduced myocardial oxygen supply may result
from weaning induced hypoxaemia and tachycardia.
Aim of the work : The aim of this work was to monitor the cardiac changes during weaning of COPD pa­tients by non invasive methods in an attempt to detect occult lethal events.
Patients and Methods:
This prospective study included 40 male COPD patients mechanically ventilated for acute on top of chronic respiratory failure, with mean age of 61.45±9.17 years. Four modes of weanin were used random-ly:sychronized intermittent mandatory ventilation SIMV) mode (11 patients), pressure support ventilation ( PSV) mode (11 patients), continous positive airway pressure (CPAP) mode