Predictive factors for early and late-onset pneumonia in post-cardiac arrest patients

Pneumonia is one of the most common complications in patients admitted following a recovered cardiac arrest (CA). However, its diagnosis remains challenging due to the wide range of confounding factors present in this clinical setting. Based on a subjective temporal criterion, pneumonia in cardiac arrest survivors has been classified as early-onset pneumonia (EOP), when it is diagnosed within first 72 hours, or late-onset pneumonia (LOP) when it appears after 72 hours (3–7 days).

This study aims to identify predictors of early and late-onset pneumonia in CA survivors that could be valuable in clinical practice.

A retrospective analysis was conducted using a prospective registry of patients who recovered from CA and then were admitted to the Intensive Cardiac Care Unit (ICCU) of a tertiary hospital between September 2006 and April 2022. The post-resuscitation care protocol included temperature control during the initial hours of admission, targeting mild-to-moderate hypothermia. Pneumonia was diagnosed using the Centers for Disease Control and Prevention (CDC) criteria, January 2023 version.

A total of 575 patients were included in the analysis, excluding 13 patients who died within the first 24 hours. Baseline characteristics of the sample are shown in Table 1. The incidence of pneumonia was 41% (235 cases), with early-onset pneumonia (EOP) occurring in 28% (161 cases). Multivariable logistic regression analysis identified independent predictors for EOP, including smoking history [OR = 3.84 (95% CI 1.99-7.42), p < 0.001] and blood glucose >100 mg/dL at 48 hours [OR = 2.87 (95% CI 1.57-5.22), p = 0.001]. Conversely, acute coronary syndrome as the cause of CA was a protective factor [OR = 0.35 (95% CI 0.18-0.67), p = 0.002] (Figure 1A). For late-onset pneumonia (LOP), C-reactive protein levels >149 mg/dL at 96 hours [OR = 5.44 (95% CI 1.98-14.93), p = 0.001] resulted to be an independent predictor (Figure 1B). Empirical antibiotic therapy on admission was administered to 53.5% of patients, with amoxicillin-clavulanic acid as the most common first-line treatment. The use of empirical antibiotics was found to be a protective factor against LOP [OR = 0.25 (95% CI 0.18-0.64), p = 0.013].