SFTPD and ventilator-associated pneumonia: Correlation between blood and bronchial levels of biomarkers: At patient level, no significant correlation was found between blood and bronchial SP-D levels for patients with high VAP suspicion on day 1 (r = −0.133; p = 0.68) and on day 6 (r = 0.2; p = 0.555): Figure 3, panel A).