Oesophageal balloon positioning by echocardiography to guide positive pressure ventilation

Abstract

Understanding the respiratory mechanics of ARDS patients is crucial to avoid ventilator-induced lung injury (VILI), and this is much more challenging if not only lung compliance is altered but the whole compliance of the respiratory system is abnormal, as in obese patients. We face this problem daily in the ICU, and to optimize ventilation, we estimate respiratory mechanics using an oesophageal balloon. The balloon position is crucial to assess reliable values. In the present technical note, we describe the use of echocardiography to confirm the correct position of this instrument.

Keywords: ARDS; COVID-19; Chest wall compliance; Oesophageal balloon; Transpulmonary pressure; Ultrasounds.

Fig. 1

Tomographic visualization of the esophageal balloon showing its strict relation with the posterior wall of the left atrium

Fig. 2

Direct visualization of esophageal balloon by PLAX window: A Visualization of the nasogastric tube as an hyperechogenic dot (white arrow) between the left atrium and the thoracic aorta; B and C After the injection of respectively 4 cc and 8 cc of air in the esophageal balloon the image of the hyperecogenic dot is replaced by à hypercogenic line and the image of the thoracic aorta disappeared because of ecographic shadowing by the balloon

Fig. 3

Indirect visualization of esophageal balloon by M-Mode in parasternal windows: A PLAX with M-Mode aiming the posterior wall of the left atrium. After the injection of 4 cc of air in the esophageal balloon we note an anterior displacement of the posterior wall of the atrium (upwards arrow) marking the presence of the esophageal balloon behind the atrium. After deflating the balloon we note the line of the posterior wall of atrium returning to the original position (downwards arrow); B The same method to visualize the balloon is used in PSAX showing the same reversible anterior displacement of the posterior wall of the atrium

Fig. 4

Direct visualization of balloon in gastric position by subxifoid window: A, a Image of the stomach (dashed line) with hyperechoic linear image that correspond to the balloon (solid line); B, b After injecting 4 cc of air in the balloon the linear hyperechoic image disappear and is remplaced by a hypercoic line with posterior shadowing confirming that the image correspond to the balloon that is misplaced in gastric position