Myocardial ischemia during the weaning period

Am J Crit Care. 1992 Nov;1(3):32-6.

Abstract

Objectives: To estimate the incidence of silent myocardial ischemia, its pattern over time and its relationship to the time and mode of weaning high-risk cardiac patients after noncardiac surgery.

Design: Prospective study with random assignment to one of three weaning modes.

Setting: A surgical intensive care unit in a university hospital and a Veterans Administration hospital.

Patients: Sixty-two patients meeting standard criteria for extubation were randomized to one of three modes of weaning: synchronized intermittent mandatory ventilation (n = 19), T-Bar (n = 21) or continuous positive airway pressure (n = 22).

Methods: Ischemia was monitored with a continuous two-lead (V5, III) ST segment analyzer. Tracings were reviewed by a cardiologist. Ischemia was defined as greater than 1 mm ST segment depression 60 milliseconds after the J point. The monitoring period included a prewean (mean 654.0 minutes), wean (mean 46.5 minutes) and postwean (mean 1223.4 minutes) period.

Results: Of 62 patients, 12 (19.3%) experienced ischemia at some time during the monitoring period, most often during the weaning period. Ischemia during weaning was detected in 3 of 21 (14.3%) T-Bar patients and 2 of 22 (9.1%) continuous positive airway pressure patients but in no synchronized intermittent mandatory ventilation patients.

Conclusion: This study demonstrates that silent myocardial ischemia occurs frequently in high-risk postoperative patients, with the highest incidence during weaning.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Aged, 80 and over
  • Electrocardiography
  • Female
  • Humans
  • Incidence
  • Intermittent Positive-Pressure Ventilation / adverse effects*
  • Intermittent Positive-Pressure Ventilation / methods
  • Male
  • Middle Aged
  • Monitoring, Physiologic
  • Myocardial Ischemia / diagnosis
  • Myocardial Ischemia / epidemiology*
  • Myocardial Ischemia / etiology
  • Myocardial Ischemia / physiopathology
  • Oxygen Consumption
  • Positive-Pressure Respiration / adverse effects*
  • Positive-Pressure Respiration / methods
  • Postoperative Complications / diagnosis
  • Postoperative Complications / epidemiology*
  • Postoperative Complications / etiology
  • Postoperative Complications / physiopathology
  • Prospective Studies
  • Risk Factors
  • Time Factors
  • Ventilator Weaning / adverse effects*
  • Ventilator Weaning / methods
  • Work of Breathing