Validation of Aspiration Markers
Validation of Aspiration Markers
This is an interventional crossover study aimed at validating diatom shells as a marker for
 cuff leak and microaspiration in mechanically ventilated, critically ill 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. Radiolabeled 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, we would
 like to validate the use of diatom skeletons suspended in saline as a marker for determining
 cuff leakage and aspiration events in an ICU population and compare its efficacy in
 identifying aspiration events with pepsin detection. Diatoms are a major group of algae,
 composing the majority of phytoplankton. Their diameter is 5-15 μm on average and 1 ml of
 seawater usually contains about 104 diatoms. They are unicellular organisms and their main
 feature is that they are enclosed within a cell wall made of amorphous silica, biopolymerized
 in a geometric fashion that is species-dependent. At the end of their vital cycle, diatom
 shells deposit at the bottom of the sea. Diatom shell deposits have been found in almost
 every place on Earth, and are the main component of diatomaceous earth (DE). DE is an
 extremely fine powder composed of diatom shells that have accumulated over thousands of
 years. Due to its microscopical texture and inexpensive nature, it is commonly employed as a
 filtering media for beverages and a drying and anti-mold agent for cereals. Diatom shells
 compose food-grade DE in its entirety. Due to its non-crystalline, amorphous nature, it is
 essentially nontoxic. Our hypothesis is that administration of 10 mg of DE suspended in 10 ml
 of saline into the pharyngeal cavity of intubated patients will act as a reliable marker of
 cuff leak and aspiration in critically ill patients. Thanks to their geometric shape, diatom
 shells should be easily detectable in tracheal secretions when observed under a microscope.
 The number of diatoms-per-field observed under a fixed magnification will allow for the
 detection of microaspiration in a qualitative and quantitative way. The introduction of this
 new, safe and inexpensive marker for evaluating ETT cuff performance and for detecting
 aspiration will improve the design of future studies aimed at VAP prevention
Inclusion Criteria:

 1. Age ≥ 18 years;

 2. Admission to Surgical ICUs (Ellison 4 or Blake 12);

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

 Exclusion Criteria:

 1. High PEEP requirement at enrollment (PEEP higher than 8 cmH2O)

 2. Diagnosis of ARDS (any severity)

 3. Status asthmaticus

 4. Current or past participation in another interventional trial conflicting with the
 present study;

 5. Pregnant women;

 6. Prisoner status;

 7. Patients who had partial or total gastrectomy.