Validation of Aspiration Markers in Intubated Patients

At present there is no standard method for the evaluation of in vivo cuff leak and
aspiration. Most of the tested techniques have major pitfalls that render their routine
application infeasible. Lacking a practical and reliable marker, any possible intervention
aimed at improving cuff seal and ETT performance in order to reduce VAP occurrence is going
to be hindered by the inability to truly evaluate its efficacy. Radio-labeled markers are
expensive, expose the patient to considerable radiological risk, and require transport to a
radiological department, which would expose critically ill patients to additional risk. Dyes
have the potential to give useful information about the presence of a cuff leak, but due to
persistent staining of secretions, they do not allow continuous monitoring of aspiration.
Amylase detection could be a good marker of aspiration, but its ability to detect aspiration
is poor even when compared to pepsin. Pepsin and bile acids have the potential to detect some
of the aspirations and cuff leaks that happen daily in mechanically ventilated patients, but
due to their gastrointestinal nature, they do not offer any kind of information about
aspiration of contaminated oropharyngeal secretions. With this research protocol, the
investigators would like to validate the use of Quinine suspended in sterile water as marker
for determining cuff leakage and aspiration events in an ICU population. Quinine is compound
commonly used in food manufacturing. His pharmacokinetic and -dynamic has extensively been
studied. The chemical structure of this molecule allows the detection up to pico-molar
concentration by spectrophotometry.

The investigators will challenge the oropharyngeal cavity with a known concentration of
Quinine suspended in sterile water. The investigators hypothesized that the detection by
spectrophotometry of the same substance in the tracheal secretions will prove aspiration.

The investigators specific aims are:

1. To quantify the measurements of Quinine in the tracheal sample and compare with the
measurements of Quinine in the oral sample.

2. To assess association between the amount of oropharyngeal aspiration and the development
of upper and lower respiratory complications (i.e. ventilator associated pneumonia
[VAP], tracheobronchitis, ventilator-associated events, acute respiratory distress
syndrome [ARDS], etc.).

3. To determine patient's risk factors associated with oropharyngeal aspiration. The
introduction of this new, safe and inexpensive markers for evaluating ETT cuff
performance and for detecting aspiration will improve the design of future studies aimed
at VAP prevention.

Inclusion Criteria:

- Age ≥ 18 years

- Admission to Surgical ICUs (MGH Ellison 4 or Blake 12)

- Patients expected to be intubated for at least 48 hours or longer from the time of
enrollment.

Exclusion Criteria:

- High PEEP requirement at enrollment (PEEP higher than 8 cmH2O)

- Diagnosis of ARDS (any severity)

- Status asthmatics

- Current or past participation in another interventional trial conflicting with the
present study

- Pregnant women

- Prisoner status

- Patients who had partial or total gastrectomy.