The pathophysiology of post-extubation dysphagia in ICU patients

Mechanical ventilation is a widely used treatment on the intensive care unit
(ICU). It is a life-sustaining intervention in patients suffering from acute
respiratory failure and in patients who need temporary support after major
surgery. About 10% of all extubated patients are reintubated.
An important factor that may contribute to reintubation in these patients is
swallowing dysfunction (dysphagia). Oral intake may then result in aspiration
and subsequently pneumonia. Dysphagia in ICU patients after endotracheal
intubation was found to be associated with an increased reintubation rate,
length of hospital stay and mortality. Poor outcomes of dysphagia were also
shown in a general population of hospitalized patients: a significant
association was found with aspiration pneumonia, length of hospital stay and
mortality. Dysphagia has a substantial impact on hospital resources like
antibiotic prescription, placement of feeding tubes and hospital and ICU length
of stay. Estimated costs are almost 550 million dollars in the USA per year.
Aspiration may be prevented by feeding through a nasogastric feeding tube, and
dysphagia may be treated by diet modifications, postural changes, compensatory
manoeuvres and training exercises.
Lately, increased attention has been drawn to swallowing dysfunction in ICU
patients. Although the exact frequency is unknown, swallowing dysfunction after
extubation is common: the frequency ranges from 3 to 62% and the frequency of
aspiration from 3 to 56%. These wide ranges are probably due to heterogeneity
and bias among studies of dysphagia post-extubation (PED).
The etiology is multifactorial and probably develops via several mechanisms:
direct laryngeal trauma of the endotracheal tube, impaired sensibility,
impaired swallowing reflex, neuromuscular weakness, discoordination and
impaired cognition. However, after prolonged intubation, the pathophysiology of
swallowing disorders has never been studied properly. Currently, the
mechanism(s) of dysphagia in these patients are unknown, preventing precise
recommendations regarding management of PED.
A recent international consensus meeting put dysphagia in ICU patients on the
research agenda. The working group of the European Society of Intensive Care
Medicine recommends to conduct large prospective studies including both
pathophysiology and therapy.
In conclusion, post-extubation dysphagia is associated with poor clinical
outcomes but the pathophysiology after prolonged intubation is largely unknown.
This pilot study is the first step that aims to fill this knowledge gap to
ultimately improve current treatment and prevention of dysphagia and its most
important complication aspiration pneumonia.

Primary Objective: to determine the pathophysiology of post-extubation
dysphagia in ICU patients after prolonged endotracheal intubation using
simultaneously recorded flexible endoscopic evaluation of swallowing (FEES),
high resolution impedance manometry (HRIM) en electromyography (EMG).

Secondary Objective: to assess the feasibility of combining these techniques
(simultaneously recorded FEES, HRIM and EMG) en studying potential interactions
in healthy subjects.

A prospective observational study. The study duration is about 1 hour (and will
be performed in patients within 24 hours post-extubation). FEES, HRIM and EMG
will be simultaneously recorded. The EMG electrodes will be placed below the
chin, the flexible endoscope will be introduced and the manometry catheter will
be inserted. During the investigation, the subjects will swallow small sips of
saline colored with methylene blue, and possibly thicker liquids and solid
food.

The burden and risks of the study are considered as low. FEES and manometry are
invasive measurements but are widely applied at the outpatient department of
the ENT and gastroenterology departments. Most patients are not or mildy
uncomfortable during the FEES. Risks are negligible, the techniques are
considered to be safe.