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Tracheal amylase dosage as a marker for microaspiration: a pilot study
1Medical Intensive Care Unit, CHU Bordeaux, Bordeaux, France - alexandre.boyer@chu-bordeaux.fr.
Background:
Devices that limit microaspiration through the cuffs of endotracheal tubes could help prevent ventilator-associated pneumonia (VAP). The amount of tracheal microaspirations could be a relevant study endpoint. The aim of our study was to assess whether amylase measured in tracheal secretions constituted a relevant marker for microaspiration.
Methods:
Twenty-six patients, intubated for at least 48 h and supplied with a subglottic secretion-suctioning device, constituted a group with a high risk of microaspiration. Twelve non-ventilated patients that required a bronchoscopy procedure constituted a group with a low risk of microaspiration (the control group). Tracheal (T) amylase was compared between the groups. In the intubated group, a series of oral (O), subglottic (Sg) and tracheal (T) suction samples were collected and T/O, T/Sg, Sg/O amylase ratios were determined.
Results:
Amylase was measured in 277 (89 Sg, 96 B, 92 T) samples from the intubated group and in 12 T samples from the control group. Tracheal amylase was lower in the control group than the intubated group (191 [10-917] vs. 6661 [2774-19,358] IU/L, P<0.001). Amylase gradually increased from tracheal (6661 [2774-19,358] IU/L), to subglottic (130,750 [55,257-157,717] IU/L), to oral samples (307,606 [200,725-461,300] IU/L), resulting in a median 5.5% T/O ratio. In a subset of intubated patients, T amylase samples were assessed in two different laboratories, and gave reproducible results.
Conclusion:
Tracheal amylase was easy to collect, transport, and measure. The T/O amylase ratio is a first step towards quantifying oropharyngeal to tracheal microaspiration in mechanically-ventilated patients.
Insights
Measuring amylase in tracheal secretions is a viable method to detect microaspiration in intubated patients. This finding could lead to better prevention strategies for ventilator-associated pneumonia (VAP).
Area of Science:
- Critical Care Medicine
- Pulmonology
- Biochemistry
Background:
- Ventilator-associated pneumonia (VAP) is a concern in intubated patients.
- Devices limiting microaspiration may prevent VAP.
- Tracheal microaspiration quantification is a potential study endpoint.
Purpose of the Study:
- To evaluate amylase in tracheal secretions as a marker for microaspiration.
- To compare tracheal amylase levels between high-risk and low-risk microaspiration groups.
Main Methods:
- Studied 26 intubated patients (high-risk) and 12 non-ventilated patients (control).
- Collected tracheal, subglottic, and oral suction samples.
- Measured amylase levels and calculated tracheal/oral (T/O) and tracheal/subglottic (T/Sg) ratios.
Main Results:
- Tracheal amylase was significantly higher in intubated patients (6661 IU/L) than controls (191 IU/L).
- Amylase levels increased from tracheal to subglottic to oral samples.
- A median T/O amylase ratio of 5.5% was observed, with reproducible laboratory results.
Conclusions:
- Tracheal amylase is an easily measurable marker for microaspiration.
- The T/O amylase ratio aids in quantifying oropharyngeal to tracheal microaspiration.
- This marker could improve VAP prevention strategies.
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