Risk factors for early-onset respiratory infection in a general intensive care unit (ICU)

Background

Early-onset respiratory infection (EORI) is frequent in the ICU setting. Its incidence maybe related with the presence of some risk factors.

Objective

The aim of this study was to identify risk factors and describe the epidemiological patterns of those patients who are diagnosed with respiratory infection within 72 hours of ICU admission.

Methods

The authors retrospectively studied potential risk factors and epidemiological data at the time of ICU admission among all patients admitted during the period from January to September 2000. Patients were considered to have EORI when they met the following clinical criteria, within 72 h of ICU admission: 1 – Fever (≥ 38.5°C, axilar); 2 – Leucocytosis (≥ 10,000 per mm³); 3 – Purulent respiratory secretions. Pneumonia was defined as the same criteria plus the detection by chest X-ray of new and persistent infiltrate.

Results

During the study period 385 patients were admitted to our unit. The ICU length of stay was longer for patients with EORI (8.8 ± 9.2 day; P < 0.001) and LORI (14.0 ± 9.7 days) as compared to patients without respiratory infection (2.7 ± 2.8 days). Multivariate analysis selected the presence of one co morbidity (OR: 2.4; CI: 1.0-5.6); the existence of one risk factor (OR: 2.4; CI: 1.1-5.3) or at least two risk factors (OR: 4.1; CI: 1.7-9.8); the presence of two or more conditions that altered ventilatory mechanics (OR: 6.1; CI: 1.3-28.1) and emergency intubation (OR: 3.2; CI: 1.0-10.3) as significant factors for the development of EORI. Depressed level of consciousness (OR: 1.9; CI:1.0-3.8) and documented aspiration (OR: 4.4; CI: 1.0-20.4) were the only studied risk factors that were independently associated with EORI.

Conclusions

EORI has a high prevalence (45.1%) in our unit. Both EORI and LORI are associated with prolonged ICU lengths of stay. The presence of more than one risk factor has a strong association with EORI but depressed level of consciousness and documented aspiration were the only risk factors independently related to EORI. The existence of two or more conditions that disrupt ventilatory mechanics is a significant risk factor for EORI. Emergency intubation was also identified as a significant risk factor for EORI.