Effects of Intraoperative Ventilation Strategy on Perioperative Atelectasis Assessed by Lung Ultrasonography in Patients Undergoing Open Abdominal Surgery: a Prospective Randomized Controlled Study

Abstract

Background: Protective mechanical ventilation using low tidal volume has been introduced to surgical patients to reduce the incidence of postoperative pulmonary complications. We investigated the effects of protective ventilation (PV) techniques on anesthesia-induced atelectasis identified via lung ultrasonography in patients undergoing abdominal surgery. Methods: A total of 42 adult patients who were scheduled for open abdominal surgery with an expected duration > 2 hours were included in the study. Patients were randomized to receive either conventional ventilation (CV; tidal volume of 9-10 mL/kg predicted body weight [PBW] with no positive end-expiratory pressure [PEEP]) or PV (tidal volume of 6-8 mL/kg PBW and 5 cmH 2 O PEEP) via pressure-controlled ventilation with volume guaranteed. Lung ultrasonography was performed at four predefined time points to assess perioperative atelectasis by dividing each hemithorax into six quadrants based on a modified lung ultrasound (LUS) scoring system. Results: The tidal volume delivered to patients was 9.65 ± 1.65 mL/kg PBW in the CV group and 6.31 ± 0.62 mL/kg PBW in the PV group. Ventilation using low tidal volume led to similar LUS scores in all lung areas and at all time points compared to ventilation using high tidal volume. There was no significant difference between the groups in the number of patients requiring recruitment maneuvers at the end of surgery. Conclusion: Ventilation with low tidal volume combined with 5 cmH 2 O PEEP did not cause further loss of aeration compared to ventilation with high tidal volume. Low tidal volume ventilation can be used in patients without lung injury based on lung assessment by bedside lung ultrasonography.

Effect of driving pressure on early postoperative lung gas distribution in supratentorial craniotomy: a randomized controlled trial

“…No hypoxemia was observed in either group. In patients who underwent open abdominal surgery in a previous study, the changes in the LUSs were moderately correlated with changes in PaO 2 /FiO 2 [ 23 ].…”

“…B-lines are defined as hyperechoic vertical artifacts that originate from the pleural line, reach the bottom of the screen without fading and move synchronously with lung sliding [ 22 ]. Sets of at least three hyperechoic B-lines arising from the pleural line in one intercostal space are indicative of interstitial lung syndrome [ 23 ]. Each hemithorax was divided into six quadrants using two longitudinal lines (anterior and posterior axillary) and one axial line at the level of the nipples.…”

Assessment of Perioperative Atelectasis Using Lung Ultrasonography in Patients Undergoing Pneumoperitoneum Surgery in the Trendelenburg Position: Aspects of Differences according to Ventilatory Mode

“…The advantage of this view is assessing anesthetized patients’ lungs in the supine position as our study did. Cho et al 34 also reported the difficulty of assessing postererobasal side of the lung. They tried using additional oblique scans along the intercostal space in the posterior region of the lung, but B-lines were still obscured by rib acoustic shadowing.…”