Mortality associated with invasive mechanical ventilation

Introduction

Few studies exist analysing the handling of acute respiratory insufficiency with invasive mechanical ventilation (IMV) and its correlation with mortality among the elderly intensive care unit (IUC) patient population.

Objectives

To analyse the IMV association with mortality rate in patients in their seventh decade of life in a clinical ICU.

Methods

A prospective cohort, enrolling 615 patients admitted to a clinical ICU in the period from July 2001 to August 2001, of which 70% were older than 65 years, were studied. Thirty consecutive patients older than 65 years needed IMV for more than 24 hours and were eligible for this study. The analysis was performed considering the following variables: clinical (age, gender, Acute Physiology and Chronic Health Evaluation [APACHE] II score, systolic blood pressure and cardiac frequency at the time of admission), laboratory (hematocrit, hemoglobin, leucocyte count, albumin and seric lactate) and mechanical ventilation parameters (length of IMV needed, FiO₂, positive end expiratory pressure, static and dynamic compliance). The significance level was 5%, using the Student t test, Pearson's correlation, the Kruskal–Wallis test, the Exact Fisher test, the Mantel–Haenszel test and analysis of variance.

Results

The results showed a mean age of 79 ± 9.7 years and a preponderance of the male gender (58%). The mean APACHE II score was 16.7 ± 7.1 and the average time of requiring the IMV was 12.6 ± 8 days. Although the cohort mortality was 13%, this rate in patients submitted to IMV was 52%. Among all the variables studied, the following had a correlation with death: pulmonary septic shock (P = 0.01), cardiogenic shock (P = 0.01), inotropic drugs use (P = 0.01), acute coronary syndrome (P = 0.01) and cardiac failure during ICU hospitalization (P = 0.01).

Conclusions

In patients older than 65 years IMV was associated with significant mortality, and the inotropic drugs used, pulmonary septic shock, cardiogenic shock, acute coronary syndrome and the cardiac failure during ICU hospitalization were the only variables studied that were related with death.