Postural lung recruitment assessed by lung ultrasound in mechanically ventilated children

Abstract

Background: Atelectasis is a common finding in mechanically ventilated children with healthy lungs. This lung collapse cannot be overcome using standard levels of positive end-expiratory pressure (PEEP) and thus for only individualized lung recruitment maneuvers lead to satisfactory therapeutic results. In this short communication, we demonstrate by lung ultrasound images (LUS) the effect of a postural recruitment maneuver (P-RM, i.e., a ventilatory strategy aimed at reaerating atelectasis by changing body position under constant ventilation).

Results: Data was collected in the operating room of the Hospital Privado de Comunidad, Mar del Plata, Argentina. Three anesthetized children undergoing mechanical ventilation at constant settings were sequentially subjected to the following two maneuvers: (1) PEEP trial in the supine position PEEP was increased to 10 cmH₂O for 3 min and then decreased to back to baseline. (2) P-RM patient position was changed from supine to the left and then to the right lateral position for 90 s each before returning to supine. The total P-RM procedure took approximately 3 min. LUS in the supine position showed similar atelectasis before and after the PEEP trial. Contrarily, atelectasis disappeared in the non-dependent lung when patients were placed in the lateral positions. Both lungs remained atelectasis free even after returning to the supine position.

Conclusions: We provide LUS images that illustrate the concept and effects of postural recruitment in children. This maneuver has the advantage of achieving recruitment effects without the need to elevate airways pressures.

Keywords: Airways; Anesthesia-induced atelectasis; Children; Lung recruitment; Lung ultrasound; Mechanical ventilation; Outcome; PEEP; Respiration.

Fig. 1

Concept of postural lung recruitment. Theoretical explanations of the postural recruitment maneuver in an anesthetized child 6 years of age. The maneuver consists of sequential changes in body position from supine to both lateral positions and back to supine again, keeping ventilatory settings constant. The gradient of trans-pulmonary pressures (Ptp) differs between body positions due to the elliptical shape of the chest with the gravity-dependent thoracic dimension being larger in lateral than in the supine position (yellow arrows). Thus, the lower half of the lungs is predisposed to collapse while the upper half is usually aerated and “open” during the entire respiratory cycle (red dotted line). In the left lateral position (LL), the entire right upper lung has the chance to open up at a low plateau pressures even under standard ventilator settings (gray lung). Once open, this right lung can maintain its “open lung” condition when turned to the right lateral positioning (RL) provided sufficient PEEP is applied. Notice the larger vertical distance in the lateral position required a higher PEEP to counteract the potential decrease in Ptp in the dependent lung. Now, the left lung is being recruited as it is placed in the uppermost gravity non-dependent position. At the end of the postural recruitment maneuver both lungs are free from atelectasis although the patient has returned to the baseline supine position

Fig. 2

Lung ultrasound images of postural recruitment. Example of the postural recruitment effect in one anesthetized child (case 1–24 months). This patient was subjected to 10 cmH₂O of positive end-expiratory pressure (PEEP) in the supine position and then during the postural recruitment maneuver. Bilateral atelectasis was diagnosed placing the ultrasound linear probe in the oblique position over the juxta-diaphragmatic lung areas. The same pulmonary areas were assessed in each body position. Note that atelectatic areas are reaerated only after the postural changes

Fig. 3

Lung ultrasound images of postural recruitment in case 2 and 3