Effects of heated humidification on nasal inflammation in a CPAP rat model

BackgroundRhinitis is a potential side effect of nasal continuous positive airway pressure (nCPAP). Heated Humidification (HH) is applied to treat rhinitic symptoms, but its usefulness is controversial. Confounding factors such as previous rhinitis or nasal obstruction make it difficult to draw definitive conclusions. Animal models could therefore be useful.ObjectivesTo study the effects of HH as a mechanism that may reduce nasal inflammation during nCPAP application in the presence or absence of an oral leak (OL).MethodsProspective controlled animal study.Setting I: Sixty Sprague–Dawley rats were distributed into noCPAP (naïve), sham-CPAP with HH, 5 and 10 cm H2O nCPAP, and 10 cm H2O nCPAP with HH for 5 h.Setting II: Thirty-three rats were exposed to nCPAP, nCPAP with a controlled OL, and nCPAP with controlled OL and HH (n = 11 each).The degree of nasal inflammation was assessed by directly evaluating the percentage of neutrophils in the nasal mucosa.ResultsPercentage of neutrophils was higher after 5 h of 10 cm nCPAP compared to the control group (0.96 ± 0.26% vs. 0.18 ± 0.05%; p = 0.001). When HH was applied, the percentage of neutrophils did not differ from that observed in the nCPAP group. The addition of a controlled OL, did not show significant differences in the neutrophils count compared to nCPAP alone (0.75 ± 0.19% vs. 0.83 ± 0.29%; p = 0.70). Moreover, the application of HH to the rat with OL did not change the percentage of neutrophils.ConclusionsHH applied to an acute rat model of nCPAP with and without a controlled OL does not seem to reduce nasal inflammation.