Mojoli F, Torriglia F, Giannantonio M, Orlando A, Bianzina S, Tavazzi G, Mongodi S, Pozzi M, Iotti GA, Braschi A, PLUG Working Group

Intensive Care Medicine Experimental 2016, 4(Suppl 1):27; 534

Introduction: A calibration procedure has been recently proposed to

obtain reliable esophageal pressure (Pes) measurements in mechanically

ventilated patients [1]. This procedure helps optimizing esophageal

balloon filling and removing esophageal artifacts, but is timeconsuming.

Objectives: To test accuracy of a simplified procedure, designed according

to average values of esophageal elastance (Ees) and minimum

appropriate filling volume (Vmin) previously observed [1].

Methods: In 15 patients under Pressure Controlled Ventilation, 35

pairs of end-expiratory and end-inspiratory calibrated Pes values

(Pes,cal) were obtained with the standard procedure, consisting in

measure of Ees and detection of Vmin and Vbest (filling volume associated

with the largest tidal swings of Pes): Pes,cal = Pes – Ees *

(Vbest – Vmin). “Simplified” calibrated Pes values (S-Pes,cal) were also

obtained with a simplified procedure based on detection of Vbest

and on the assumptions that Ees = 1 cmH2O/ml and Vmin = 1 ml: SPes,

cal = Pes – (Vbest – 1). We used the Nutrivent catheter (Sidam,

Italy), equipped with an esophageal balloon that is 10 cm long and

has a 10 ml nominal volume.

Results: In the 35 conditions tested, Vmin was 1.4 ± 0.5 ml, Vbest 4.2

± 1.9 ml and Ees 1.2 ± 0.3 cmH2O/ml. At optimal filling volume

(Vbest), difference between Pes and Pes,cal was 3.1 ± 1.9 cmH2O

(range 0.0-8.0). S-Pes,cal strictly correlated with Pes,cal (R2 = 0.97; p <

0.0001); difference between S-Pes,cal and Pes,cal was −0.1 ± 0.9

cmH2O (Figure 102).

Conclusions: When optimal filling of the esophageal balloon is

adopted in mechanically ventilated patients, absolute values of Pes

are affected by significant esophageal artifact. A simplified calibration

procedure seems to be adequately accurate in removing this artifact

and suitable for clinical use.

References

1) Mojoli et al. Critical Care 2016, 20:98.

Grant acknowledgment

None

From Springer Open Access ICMX