Experimental Assessment of Cuff Pressures on the Walls of a Trachea-Like Model Using Force Sensing Resistors: Insights for Patient Management in Intensive Care Unit Settings

Abstract

The COVID-19 outbreak has increased the incidence of tracheal lesions in patients who underwent invasive mechanical ventilation. We measured the pressure exerted by the cuff on the walls of a test bench mimicking the laryngotracheal tract. The test bench was designed to acquire the pressure exerted by endotracheal tube cuffs inflated inside an artificial model of a human trachea. The experimental protocol consisted of measuring pressure values before and after applying a maneuver on two types of endotracheal tubes placed in two mock-ups resembling two different sized tracheal tracts. Increasing pressure values were used to inflate the cuff and the pressures were recorded in two different body positions. The recorded pressure increased proportionally to the input pressure. Moreover, the pressure values measured when using the non-armored (NA) tube were usually higher than those recorded when using the armored (A) tube. A periodic check of the cuff pressure upon changing the body position and/or when performing maneuvers on the tube appears to be necessary to prevent a pressure increase on the tracheal wall. In addition, in our model, the cuff of the A tube gave a more stable output pressure on the tracheal wall than that of the NA tube.

Keywords: COVID-19; acute respiratory distress syndrome; intensive care unit; intubation; modeling; tracheal lesions; tracheoesophageal fistula.

Figure 1

Front view and longitudinal cross-section of the prototype.

Figure 2

Interlink FSR^® Model 400 mechanical data (left) and typical force vs. resistance response (right) from the datasheet [14].

Figure 3

FSRs experimental characterization curve expressed as applied calibrated weight vs. ADC input voltage.

Figure 4

Statistical analysis to determine the differences in pressure, if any, before performing a maneuver. (A–D) Box plots showing the comparison between non-armored (NA) and armored (A) tubes across diameters of the trachea and position (S—supine, P—prone). (E–H) Box plots showing the comparison between body position (S/P) against diameters and type of endotracheal tube (NA/A). Legend: ** p < 0.001, * 0.002 < p ≤ 0.05, and + p > 0.05.

Figure 5

Statistical analysis to determine the differences in pressure variations, if any, after performing a maneuver. (A–D) Histograms showing a comparison between non-armored (NA) and armored (A) tubes across diameters of the trachea and position (S—supine, P—prone). (E–H) Histograms showing the comparison between body position (S/P) across diameters and type of endotracheal tube (NA/A). Legend: ** p < 0.001, * 0.002 < p ≤ 0.05, and + p > 0.05.