Association of myocardial ischemia with failure to wean from mechanical ventilation

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Abstract
Objective To determine if myocardial ischemia, as detected by continuous electrocardiographic monitoring, is correlated with continued ventilator dependence in patients who have had difficulties weaning from mechanical ventilation. Design A prospective, observational study. Setting A university, tertiary care hospital. Patients Seventeen medical and postsurgical patients (age 70 plus minus 9 yrs; range 54 to 84) who had received mechanical ventilation for 5 to 67 days at the time of entry into the study. Interventions None. Measurements and Main Results Patients wore a calibrated, frequency-modulated, two-channel electrocardiographic recorder with two bipolar chest leads attached to exploring electrodes for 24 hrs. We recorded the following data: a) electrocardiographic evidence of myocardial ischemia; b) eventual separation from mechanical ventilation; c) whether the patient survived to be discharged from the hospital; d) duration of tracheal intubation and mechanical ventilation; and e) length of hospital stay. The key outcome variable tested was successful weaning, which was defined as breathing without mechanical ventilatory assistance on discharge from the hospital. Six (35%) of 17 patients had electrocardiographic evidence of myocardial ischemia at the time of entry into the study. The presence of ischemia was associated with failure to wean from mechanical ventilation (p less than .05; relative risk 3.05). Conclusions Myocardial ischemia (as detected by a 24-hr, continuous Holter monitor) occurs frequently in ventilator-dependent patients. The occurrence of ischemia was associated with failure to wean from mechanical ventilation in this patient population. (Crit Care Med 1995; 23:1475-1480)