Lung ultrasound assessment will be performed by a blinded trained anesthesiologist. As shown in a previous study, ultrasound scanning will select a 5–12 MHz linear transducer (SonoSite M-Turbo) to parallelly scan all the intercostal space of 12 regions from right to left, anterior to posterior of patients’ chest in the supine position [25 (link)]. The six regions are divided by anterior midline, clavicular midline, anterior axillary line, posterior axillary line, and pectoral nipple line in each hemithorax. This anesthesiologist will complete the assessment according to the LUS criteria at the same time as scanning, and the significant images and videos will be recorded.
Atelectasis LUS criteria: 0 indicates normally ventilated areas with lung sliding sign: A-line, or isolated B-lines (< 3); 1 indicates a mild reduction in lung ventilation/moderate loss of lung tissue gasification; B lines (≥ 3) with clear boundary, regular distribution, and spacing ≥ 7 mm, or irregular, clear interval; 2 indicates a severe reduction in lung ventilation/severe lung tissue gasification: multiple coalescent B-lines spaced ≤ 3 mm and continuous fusion; 3 indicates atelectasis/pulmonary consolidation: tissue-like signs, fragment signs, and bronchial inflation signs.
Atelectasis LUS criteria: 0 indicates normally ventilated areas with lung sliding sign: A-line, or isolated B-lines (< 3); 1 indicates a mild reduction in lung ventilation/moderate loss of lung tissue gasification; B lines (≥ 3) with clear boundary, regular distribution, and spacing ≥ 7 mm, or irregular, clear interval; 2 indicates a severe reduction in lung ventilation/severe lung tissue gasification: multiple coalescent B-lines spaced ≤ 3 mm and continuous fusion; 3 indicates atelectasis/pulmonary consolidation: tissue-like signs, fragment signs, and bronchial inflation signs.