Esophageal pressure balloon and transpulmonary pressure monitoring in airway pressure release ventilation: a different approach

Abstract

This is a case of Acute Respiratory Distress Syndrome managed using esophageal balloon catheter to adjust inspiratory pressure and positive end expiratory pressure according to the inspiratory and expiratory transpulmonary pressures. There are no studies that examine the transpulmonary pressures in airway pressure release ventilation (APRV). We aimed to test the feasibility of using the esophageal balloon in the nonconventional mode of APRV. All pressures were observed when switching the mode from a pressure-controlled mode to APRV using the same inspiratory pressure and using various incremental release times (T_Low)to calculate the expiratory transpulmonary pressure. At all T_Low levels the transpulmonary pressure at end exhalation was in the negative value indicating alveolar collapse. A larger study is needed to confirm our findings and to help guide setting APRV.

Keywords: APRV; PEEP; esophageal balloon; transpulmonary pressure.

FIGURE 1. Ventilator graphics display during pressure-controlled ventilation. On the X axis from top to bottom: airway pressure, esophogeal pressure, and transpulmonary pressure, all in cmH2O. Y axis is time in seconds.

FIGURE 2. Ventilator graphics display during APRV showing summary of airway pressure, esophogeal pressure, transpulmonary pressure, all in cmH2O and flow in L/min, on X axis during different release times (0.1 – 0.7 s). Y axis is time in seconds.

FIGURE 3. Ventilator graphics display during volume-controlled ventilation with an inspiratory hold maneuver to calculate the static compliance of respiratory system and airway resistance. On the X axis from top to bottom: airway pressure, esophogeal pressure, and transpulmonary pressure all in cmH2O. Y axis is time in seconds.

FIGURE 4. Lung simulator diagram of airway pressure release ventilation: volume (yellow), lung pressure (white), and flow (orange)/time curve. Time constant (TC) was known and the TLow was set to more than 4 TCs. The blue vertical lines represent each TC. Intrinsic PEEP at each TC would be equal to the point intersecting with the pressure curve, or it can be calculated as the end expiratory lung volume divided by respiratory compliance. Notice that at each TC the flow curve did not decay to 36.2% from its previous value as expected per the mathematical model. Reproduced with permission from Respiratory Care [5].

FIGURE 5. Ventilator graphic display during APRV with an expiratory hold maneuver to calculate auto-PEEP, total PEEP, and end expiratory transpulmonary pressure at the end of the release time. On the X axis from top to bottom: airway pressure, esophageal pressure, and transpulmonary pressure all in cmH2O and flow in L/min. Y axis is time in seconds.