Invasive mechanical ventilation in cardiogenic shock complicating acute myocardial infarction: A contemporary Danish cohort analysis

Purpose: Invasive mechanical ventilation (IMV) is widely used in patients with cardiogenic shock following acute myocardial infarction (AMICS), but evidence to guide practice remains sparse. We sought to evaluate trends in the rate of IMV utilization, applied settings, and short term-outcome of a contemporary cohort of AMICS patients treated with IMV according to out-of-hospital cardiac arrest (OHCA) at admission. Methods: Consecutive AMICS patients receiving IMV in an intensive care unit (ICU) at two tertiary centres between 2010 and 2017. Data were analysed in relation to OHCA. Results: A total of 1274 mechanically ventilated AMICS patients were identified, 682 (54%) with OHCA. Frequency of IMV increased during the study period, primarily due to higher occurrence of OHCA admissions. Among 566 patients with complete ventilator data, positive-end-expiratory pressure, inspired oxygen fraction, and minute ventilation during the initial 24 h in ICU were monitored. No differences were observed between 30-day survivors and non-survivors with OHCA. In non-OHCA, these ventilator requirements were significantly higher among 30-day non-survivors (P for all<0.05), accompanied by a lower PaO2/FiO2 ratio (median 143 vs. 230, P < 0.001) and higher arterial lactate levels (median 3.5 vs. 1.5 mmol/L, P < 0.001) than survivors. Physiologically normal PaO2 and pCO2 levels were achieved in all patients irrespective of 30-day survival and OHCA status. Conclusion: In the present contemporary cohort of AMICS patients, physiologically normal blood gas values were achieved both in OHCA and non-OHCA in the early phase of admission. However, increased demand of ventilatory support was associated with poorer survival only in non-OHCA patients.