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Respiratory mucus pH in tracheostomized intensive care unit patients: Effects of colonization and pneumonia
D R Karnad1, D G Mhaisekar, K V Moralwar
1Department of Medicine, King Edward Memorial Hospital, Parel, Bombay, India.
Abstract:
Daily, we studied the effects of colonization and pneumonia on the pH of respiratory mucus in 23 critically ill patients. Sixteen patients had tracheobronchial colonization, and 11 of these subsequently developed pneumonia. Two other patients developed pneumonia without prior colonization. For the 13 patients with pneumonia, there was a significantly greater decrease in pH below the value recorded on the day of intubation vs. that for the ten patients who did not have pneumonia. In the 11 patients who developed initial colonization and then pneumonia, the pH did not change after colonization, but became acidic with the development of pneumonia. The pH returned to basal levels after recovery from pneumonia. We tested the pH value to differentiate between colonization and infection in these intubated critically ill patients. A decrease in pH greater than or equal to 0.2 below the pH value on the day of intubation could predict the presence of pneumonia with a positive predictive value of 90%. This decrease in pH occurred before or on the same day as the development of radiologically detectable pneumonia in most cases. Daily monitoring of the pH of tracheal mucus may be of value in critically ill intubated patients.
Insights
Respiratory mucus pH changes can indicate pneumonia in critically ill patients. A drop of 0.2 or more below intubation baseline pH accurately predicts pneumonia, aiding early detection.
Area of Science:
- Critical Care Medicine
- Respiratory Physiology
- Infectious Diseases
Background:
- Tracheobronchial colonization and pneumonia are common complications in critically ill intubated patients.
- Monitoring respiratory mucus can provide insights into the patient's condition.
Purpose of the Study:
- To investigate the impact of colonization and pneumonia on respiratory mucus pH in critically ill patients.
- To evaluate the utility of pH monitoring for differentiating colonization from pneumonia.
Main Methods:
- Daily pH measurements of respiratory mucus were taken in 23 critically ill intubated patients.
- Patients were monitored for tracheobronchial colonization and the development of pneumonia.
- pH changes were compared between patients with and without pneumonia.
Main Results:
- Patients with pneumonia exhibited a significantly greater decrease in mucus pH compared to those without pneumonia.
- In patients who developed pneumonia after colonization, pH remained stable during colonization but decreased significantly with pneumonia onset.
- A decrease in pH ≥0.2 below the intubation day value predicted pneumonia with 90% positive predictive value, often preceding radiological detection.
Conclusions:
- Daily monitoring of tracheal mucus pH is a valuable tool for detecting pneumonia in critically ill intubated patients.
- A significant decrease in mucus pH can serve as an early indicator of pneumonia, potentially before radiological confirmation.
- pH monitoring may aid in distinguishing between colonization and active infection.