Lung Ultrasound in Mechanical Ventilation: A Purposive Review

Abstract

Background/Objectives: Lung ultrasound (LUS) has emerged as a crucial bedside tool for evaluating and managing patients with respiratory failure, particularly those receiving mechanical ventilation (MV). Its ability to rapidly characterise lung pathology, including extent, severity, and progression, has established LUS as a key diagnostic and monitoring modality in both hospital and home-care settings. Methods: This narrative review analyses the specific applications of LUS in the assessment and management of patients undergoing MV, aiming to optimise ventilatory strategies. Results: We examine the role of LUS in (1) identifying patients requiring MV; (2) guiding ventilator settings (Positive End Expiratory Pressure selection, inspiratory pressure adjustment, and patient-ventilator synchrony optimisation); (3) performing and monitoring recruitment manoeuvres; (4) assessing parenchymal damage and evaluating the response to medical and ventilatory therapies; (5) detecting ventilation-associated complications; (6) facilitating weaning from MV; and (7) assisting with airway management procedures, specifically tracheostomy. The utility of Transesophageal Lung Ultrasound (TELU) is also briefly discussed. Conclusions: This review highlights the potential of LUS to improve clinical decision making and patient outcomes in the context of MV.

Keywords: diaphragm; intubation; lung ultrasound; mechanical ventilation; tracheotomy; ventilator-induced lung injury (VILI); weaning.

Figure 5

Comparative Alveolar Recruitment Protocols. (A) Ultrasound-guided pulmonary recruitment according to Tusman G et al. protocol [17]. Objective: Alveolar recruitment through ultrasound identification of lung opening and closing pressures. Area to be scanned: Consolidated areas. (B) Ultrasound-guided pulmonary recruitment according to the Belaïd Bouhemad et al. protocol [19]. Objective: Titrated alveolar recruitment focused on the anterior, less consolidated, lung areas to limit overdistension. Area to be scanned: anterior lung quadrants. This protocol involves recruitment trials with PEEP ≤ 10 cm/H₂O if there are A-lines or focal areas of aeration loss in the anterior lung areas. PEEP > 10 cm/H₂O (with increments of 3–4 cm/H₂O) will be used if the anterior areas are consolidated.

Figure 1

Primary applications of ultrasound in patients with mechanical ventilation. On the left, applications are related to the direct study of the pleuropulmonary and diaphragmatic regions using transcutaneous or transoesophageal scans. On the right, some potential ultrasound applications related to the study of other systems and organs are useful for an integrated assessment and management of patients with mechanical ventilation.

Figure 2

Thoracic zones (1–2 anterior, 3–4 lateral, 5–6 dorsal) are used to calculate the Classic Lung Ultrasound Score. A second operator is required to assist in assessing the dorsal zones in a supine patient undergoing mechanical ventilation. The presence of ribs and the scapula limits access to the pleural surface.

Figure 3

Ultrasound findings for calculating the Lung Ultrasound Score (LUSsc 0–36).

Figure 4

(A) Ultrasound-guided pulmonary recruitment according to the protocol by Tusman G et al. In this case, the opening pressure is reached with the Recruitment Manoeuvre (RM), and the closing pressure is subsequently identified by gradually reducing the airway pressure. (B) Ultrasound-guided recruitment protocol when InsP exceeds the lung opening pressure. In these cases, alveolar reopening occurs with each inspiratory effort, followed by consolidation during the expiratory phase (Video S1). The protocol involves gradually increasing Positive End Expiratory Pressure (PEEP) under ultrasound guidance until the lung closing pressure is surpassed. Ultrasound is then used to verify the maintenance of alveolar ventilation throughout all ventilatory phases (Videos S2 and S3). PIP = Peak Inspiratory Pressure.

Figure 6

Progression of pneumonia from the pleural line to the pulmonary hilum. (A) Pattern A (Normal). (B) Interstitial Disease with separate or confluent B-lines. (C) Initial alveolar involvement. Confluent B-lines, Fragmented Pleural Lines and Subpleural Lesions. (D,E) Extension of pneumonia: subpleural hypoechoic lesion, Shred Sign, hyperechoic spots, confluent B lines. (F) Extended consolidation and dynamic air bronchograms.

Figure 7

Evaluation of Right-Sided Selective Intubation with Accidental or Intentional Exclusion of the Left Lung. Evaluation performed at three levels: 1st Level—Airways: (A) Transverse scan of the airways showing the ETT in the trachea (Bullet Sign). (B) The position of the upper edge of the ETT cuff (*) is located too caudally relative to the cricoid. 2nd Level—Lung: (C) Presence of the Sea Shore Sign in the ventilated lung. (D) Lung Pulse observed in the excluded lung (arrows). 3rd Level—Diaphragm: (E) Diaphragm with regular excursions in the ventilated lung. (F) Immobile diaphragm in the excluded lung.