Purulent and non-purulent maxillary sinus secretions with respect to pO2, pCO2 and pH.

Antral secretions from patients with maxillary sinusitis were aspirated for determination of pO2, pCO2 and pH. In 14 non-purulent secretions the mean pO2 was 12.7 kPa (96 mmHg) and the mean pCO2 5.2 kPa (39 mmHg). The mean pH was slightly alkaline. In 18 purulent secretions, usually with a heavy growth of pneumococci or H. influenzae, the pO2 was zero or close to zero and the mean pCO2 greater than or equal to 10.1 kPa (greater than or equal to 76 mmHg). The mean pH was slightly acid and significantly lower than in the nonpurulent secretions. The gas composition and the pH in purulent secretions do not only influence the metabolic activity and multiplication of bacteria, but may also interfere with the local protective functions of the sinus mucosa and with the bactericidal function of granulocytes.