Association of myocardial ischemia with failure to wean from mechanical ventilation

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 +/- 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 < .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.