One-lung ventilation with fixed and variable tidal volumes on oxygenation and pulmonary outcomes: A randomized trial.

OBJECTIVE: Test the hypothesis that one-lung ventilation with variable tidal volume improves intraoperative oxygenation and reduces postoperative pulmonary complications after lung resection. BACKGROUND: Constant tidal volume and respiratory rate ventilation can lead to atelectasis. Animal and human ARDS studies indicate that oxygenation improves with variable tidal volumes. Since one-lung ventilation shares characteristics with ARDS, we tested the hypothesis that one-lung ventilation with variable tidal volume improves intraoperative oxygenation and reduces postoperative pulmonary complications after lung resection. DESIGN: Randomized trial. SETTING: Operating rooms and a post-anesthesia care unit. PATIENTS: Adults having elective open or video-assisted thoracoscopic lung resection surgery with general anesthesia were randomly assigned to intraoperative ventilation with fixed (n = 70) or with variable (n = 70) tidal volumes. INTERVENTIONS: Patients assigned to fixed ventilation had a tidal volume of 6 ml/kgPBW, whereas those assigned to variable ventilation had tidal volumes ranging from 6 ml/kg PBW ± 33% which varied randomly at 5-min intervals. MEASUREMENTS: The primary outcome was intraoperative oxygenation; secondary outcomes were postoperative pulmonary complications, mortality within 90 days of surgery, heart rate, and SpO2/FiO2 ratio. RESULTS: Data from 128 patients were analyzed with 65 assigned to fixed-tidal volume ventilation and 63 to variable-tidal volume ventilation. The time-weighted average PaO2 during one-lung ventilation was 176 (86) mmHg in patients ventilated with fixed-tidal volume and 147 (72) mmHg in the patients ventilated with variable-tidal volume, a difference that was statistically significant (p < 0.01) but less than our pre-defined clinically meaningful threshold of 50 mmHg. At least one composite complication occurred in 11 (17%) of patients ventilated with variable-tidal volume and in 17 (26%) of patients assigned to fixed-tidal volume ventilation, with a relative risk of 0.67 (95% CI 0.34-1.31, p = 0.24). Atelectasis in the ventilated lung was less common with variable-tidal volumes (4.7%) than fixed-tidal volumes (20%) in the initial three postoperative days, with a relative risk of 0.24 (95% CI 0.01-0.8, p = 0.02), but there were no significant late postoperative differences. No other secondary outcomes were both statistically significant and clinically meaningful. CONCLUSION: One-lung ventilation with variable tidal volume does not meaningfully improve intraoperative oxygenation, and does not reduce postoperative pulmonary complications.

Single-Lung Ventilation in Infants for Surgical Repair of Coarctation of The Aorta Without Cardiopulmonary Bypass.

OBJECTIVE: To investigate the effect of improving the operative field and postoperative atelectasis of single-lung ventilation (SLV) in the surgical repair of coarctation of the aorta (CoA) in infants without the use of cardiopulmonary bypass (CPB). METHODS: This was a retrospective cohort study. The clinical data of 28 infants (aged 1 to 4 months, weighing between 4.2 and 6 kg) who underwent surgical repair of CoA without CPB from January 2019 to May 2022 were analyzed. Fourteen infants received SLV with a bronchial blocker (Group S), and the other 14 infants received routine endotracheal intubation and bilateral lung ventilation (Group R). RESULTS: In comparison to Group R, Group S exhibited improved exposure of the operative field, a lower postoperative atelectasis score (P<0.001), reduced prevalence of hypoxemia (P=0.01), and shorter durations of operation, mechanical ventilation, and ICU stay (P=0.01, P<0.001, P=0.03). There was no difference in preoperative information or perioperative respiratory and circulatory indicators before SLV, 10 minutes after SLV, and 10 minutes after the end of SLV between the two groups (P>0.05). Intraoperative bleeding, intraoperative positive end-expiratory pressure (PEEP), and systolic pressure gradient across the coarctation after operation were also not different between the two groups (P>0.05). CONCLUSION: This study demonstrates that employing SLV with a bronchial blocker is consistent with enhanced operative field, reduced operation duration, lower prevalence of intraoperative hypoxemia, and fewer postoperative complications during the surgical repair of CoA in infants without the use of CPB.

Delayed targeted atelectasis in a case of bronchoscopic lung volume reduction with endobronchial valves.

A woman in her late 60s with severe chronic obstructive pulmonary disease (COPD) and emphysema underwent bronchoscopic lung volume reduction (BLVR) with endobronchial valves (EBV) to address hyperinflation. The initial EBV placement has led to partial lobar atelectasis of the left lower lobe and resulted in significant improvement in the patient's symptoms and lung function. However, valve migration occurred later due to pneumothorax unrelated to valves, leading to suboptimal clinical improvement. The patient achieved delayed full lobar atelectasis 21 months after EBV placement, which led to a significant clinical improvement. The patient decided to be delisted from the lung transplant list due to the improvement. This case highlights the importance of considering delayed atelectasis as a possible outcome of EBV placement and suggests the need for further exploration of the long-term implications and associations of this procedure.

Should atelectasis be considered a pulmonary complication and indicator of poor prognosis in cystic fibrosis?

OBJECTIVE: This study examined whether bronchoscopy leads to clinicoradiological improvement in cystic fibrosis (CF) and the predictive factors. The study also investigated whether pulmonary atelectasis is a poor prognostic factor in CF. METHODS: This multicenter, case-control, observational, retrospective study included two groups of patients with CF: a case group (patients with persistent atelectasis who were followed-up at least for 2 years) and a control group (patients without atelectasis matched 1:1 by sex and age [±3 years]). We recorded demographic data, lung function test results, pulmonary complications, comorbidities, treatments (including bronchoscopies, surgery and transplantation), and deaths. RESULTS: Each group included 55 patients (case group: 20 men, mean age 25.4 ± 10.4 years; control group: 20 men, mean age 26.1 ± 11.4 years). Bronchoscopy did not lead to clinicoradiological improvement. Allergic bronchopulmonary aspergillosis (ABPA) was more frequent in the case group. Patients in the case group more frequently used inhaled steroids, their pre-atelectasis lung function was statistically worse, and they had more exacerbations during follow-up. CONCLUSION: Moderate-to-severe pulmonary disease and ABPA can favor atelectasis. Pulmonary atelectasis can be a poor prognostic factor in CF because it increases exacerbations. Despite our results, we recommend enhancing treatment, including bronchoscopy, to prevent persistent atelectasis.

Stubborn hypoxemia after mild to moderate sedation and analgesia: A case report.

INTRODUCTION: Atelectasis typically denotes the partial or complete collapse of lung segments, lobes, or lobules in individuals, leading to a compromised respiratory function. The prevalence of perioperative atelectasis may be significantly underestimated, particularly among patients subjected to general anesthesia. PATIENT CONCERNS: This article conducts a retrospective analysis of a case involving refractory hypoxemia in a patient with a liver tumor who was admitted to Yanbian University Affiliated Hospital (Yanbian Hospital) after undergoing mild-to-moderate sedation and analgesia outside the operating room. DIAGNOSIS: Based on the results of CT examination and present history, the patient was diagnosed with intraoperative atelectasis. INTERVENTION: After the surgery, the patient was transferred to the recovery ward, where nasal oxygen therapy and nebulized inhalation treatment were administered. Vital signs were closely monitored at the bedside, gradually returning to the preoperative baseline. OUTCOME: Postoperatively, the patient developed atelectasis, with the percentage of lung opacity shown in the image decreasing from 9.2% of the total thoracic cage area to 8.4%. CONCLUSION: During non-intubated intravenous anesthesia, patients with compromised pulmonary conditions are more susceptible to refractory hypoxemia. Therefore, a personalized approach should be adopted regarding oxygen concentration and the dosage and type of medication. Additionally, preparations for appropriate airway management measures are essential to safeguard patient safety in the event of respiratory issues.

Effects of small-dose S-ketamine on anesthesia-induced atelectasis in patients undergoing general anesthesia accessed by lung ultrasound: study protocol for a randomized, double-blinded controlled trial.

BACKGROUND: Atelectasis after anesthesia induction in most patients undergoing general anesthesia may lead to postoperative pulmonary complications (PPCs) and affect postoperative outcomes. However, there is still no existing effective method used for the prevention of perioperative atelectasis. S-ketamine may prevent atelectasis due to airway smooth muscle relaxation and anti-inflammatory effects. Lung ultrasound is a portable and reliable bedside imaging technology for diagnosing anesthesia-induced atelectasis. The primary objective of this study is to assess whether a small dose of S-ketamine can reduce the incidence of atelectasis after intubation, and further investigate the effects of preventing the early formation of perioperative atelectasis and PPCs. METHODS: This is a single-institution, prospective, randomized controlled, parallel grouping, and double-blind study. From October 2020 to March 2022, 100 patients (18-60 years old) scheduled for elective surgery will be recruited from Beijing Tiantan Hospital, Capital Medical University, and randomly assigned to the S-ketamine group (group 1) and the normal saline group (group 2) at a ratio of 1:1. The label-masked agents will be administered 5 min before induction, and all patients will undergo a standardized general anesthesia protocol. Related data will be collected at three time points: after radial artery puncture (T1), 15 min after tracheal intubation (T2), and before extubation (T3). The primary outcome will be the total lung ultrasound scores (LUS) at T2. Secondary outcomes will include LUS in six chest regions at T2, total LUS at T3, arterial blood gas analysis results (PaCO2, PaO2) and PaO2/FiO2 at T2 and T3, and plateau pressure (Pplat) and dynamic lung compliance (Cdyn) at T2 and T3. The incidence of postoperative complications associated with S-ketamine and PPCs at 2 h and 24 h after surgery will be recorded. DISCUSSION: This trial aims to explore whether a simple and feasible application of S-ketamine before the induction of general anesthesia can prevent atelectasis. The results of this study may provide new ideas and direct clinical evidence for the prevention and treatment of perioperative pulmonary complications during anesthesia. TRIAL REGISTRATION: ClinicalTrials.gov NCT04745286. Registered on February 9, 2021.

The role of lung ultrasound for detecting atelectasis, consolidation, and/or pneumonia in the adult cardiac surgery population: A scoping review of the literature.

OBJECTIVES: Postoperative pulmonary complications (PPCs) frequently occur after cardiac surgery and may lead to adverse patient outcomes. Traditional diagnostic tools such as auscultation or chest x-ray have inferior diagnostic accuracy compared to the gold standard (chest computed tomography). Lung ultrasound (LUS) is an emerging area of research combating these issues. However, no review has employed a formal search strategy to examine the role of LUS in identifying the specific PPCs of atelectasis, consolidation, and/or pneumonia or investigated the ability of LUS to predict these complications in this cohort. The objective of this study was to collate and present evidence for the use of LUS in the adult cardiac surgery population to specifically identify atelectasis, consolidation, and/or pneumonia. REVIEW METHOD USED: A scoping review of the literature was completed using predefined search terms across six databases which identified 1432 articles. One additional article was included from reviewing reference lists. Six articles met the inclusion criteria, providing sufficient data for the final analysis. DATA SOURCES: Six databases were searched: MEDLINE, Embase, CINAHL, Scopus, CENTRAL, and PEDro. This review was not registered. REVIEW METHODS: The review followed the PRISMA Extension for Scoping Reviews. RESULTS: Several LUS methodologies were reported across studies. Overall, LUS outperformed all other included bedside diagnostic tools, with superior diagnostic accuracy in identifying atelectasis, consolidation, and/or pneumonia. Incidences of PPCs tended to increase with each subsequent timepoint after surgery and were better identified with LUS than all other assessments. A change in diagnosis occurred at a rate of 67% with the inclusion of LUS and transthoracic echocardiography in one study. Pre-established assessment scores were improved by substituting chest x-rays with LUS scans. CONCLUSION: The results of this scoping review support the use of LUS as a diagnostic tool after cardiac surgery; however, they also highlighted a lack of consistent methodologies used. Future research is required to determine the optimal methodology for LUS in diagnosing PPCs in this cohort and to determine whether LUS possesses the ability to predict these complications and guide proactive respiratory supports after extubation.

High Tidal Volume, High Positive End Expiratory Pressure and Apneic Breath Hold Strategies (Lung Navigation Ventilation Protocol) With Cone Beam Computed Tomography Bronchoscopic Biopsy of Peripheral Lung Lesions: Results in 100 Patients.

BACKGROUND: A dedicated anesthesia protocol for bronchoscopic lung biopsy-lung navigation ventilation protocol (LNVP)-specifically designed to mitigate atelectasis and reduce unnecessary respiratory motion, has been recently described. LNVP demonstrated significantly reduced dependent ground glass, sublobar/lobar atelectasis, and atelectasis obscuring target lesions compared with conventional ventilation. METHODS: In this retrospective, single-center study, we examine the impact of LNVP on 100 consecutive patients during peripheral lung lesion biopsy. We report the incidence of atelectasis using cone beam computed tomography imaging, observed ventilatory findings, anesthesia medications, and outcomes, including diagnostic yield, radiation exposure, and complications. RESULTS: Atelectasis was observed in a minority of subjects: ground glass opacity atelectasis was seen in 30 patients by reader 1 (28%) and in 18 patients by reader 2 (17%), with good agreement between readers (κ = 0.78). Sublobar/lobar atelectasis was observed in 23 patients by reader 1 and 26 patients by reader 2, also demonstrating good agreement (κ = 0.67). Atelectasis obscured target lesions in very few cases: 0 patients (0%, reader 1) and 3 patients (3%, reader 2). Diagnostic yield was 85.9% based on the AQuIRE definition. Pathology demonstrated 57 of 106 lesions (54%) were malignant, 34 lesions (32%) were benign, and 15 lesions (14%) were nondiagnostic. CONCLUSION: Cone beam computed tomography images confirmed low rates of atelectasis, high tool-in-lesion confirmation rate, and high diagnostic yield. LNVP has a similar safety profile to conventional bronchoscopy. Most patients will require intravenous fluid and vasopressor support. Further study of LNVP and other ventilation protocols are necessary to understand the impact of ventilation protocols on bronchoscopic peripheral lung biopsy.

Bronchoscopic treatment of pediatric atelectasis: A modified segmental insufflation-surfactant instillation technique.

BACKGROUND: Atelectasis is a condition characterized by the collapse and nonaeration of lung regions and is considered a manifestation of an underlying disease process. The goal of atelectasis treatment is the restoration of volume loss. In the range of different treatment options, chest physiotherapy is often used as a first-line approach, and some cases require bronchoscopic interventions. METHODS: In this case series, we describe a modified bronchoscopic treatment procedure using pressure-controlled bronchoscopic segmental insufflation with surfactant application. RESULTS: The proposed approach resulted in significant improvement of lung volume across a range of patients including massive lobar, atypical rounded atelectasis in previously healthy patients, and in a particularly challenging case involving an infant suffering from spinal muscular atrophy type I. CONCLUSION: The modified segmental insufflation-surfactant instillation technique offers a safe and promising easily implementable treatment of persistent atelectasis caused by different underlying disease processes with positive long-term outcomes.

Intraoperative Mechanical Power and Postoperative Pulmonary Complications in Noncardiothoracic Elective Surgery Patients: A 10-Year Retrospective Cohort Study.

BACKGROUND: Postoperative pulmonary complications is a major issue that affects outcomes of surgical patients. The hypothesis was that the intraoperative ventilation parameters are associated with occurrence of postoperative pulmonary complications. METHODS: A single-center retrospective cohort study was conducted at the Lille University Hospital, France. The study included 33,701 adults undergoing noncardiac, nonthoracic elective surgery requiring general anesthesia with tracheal intubation between January 2010 and December 2019. Intraoperative ventilation parameters were compared between patients with and without one or more postoperative pulmonary complications (respiratory infection, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm, and aspiration pneumonitis) within 7 days of surgery. RESULTS: Among 33,701 patients, 2,033 (6.0%) had one or more postoperative pulmonary complications. The lower tidal volume to predicted body weight ratio (odds ratio per -1 ml·kgPBW-1, 1.08; 95% CI, 1.02 to 1.14; P < 0.001), higher mechanical power (odds ratio per 4 J·min-1, 1.37; 95% CI, 1.26 to 1.49; P < 0.001), dynamic respiratory system compliance less than 30 ml·cm H2O (1.30; 95% CI, 1.15 to 1.46; P < 0.001), oxygen saturation measured by pulse oximetry less than 96% (odds ratio, 2.42; 95% CI, 1.97 to 2.96; P < 0.001), and lower end-tidal carbon dioxide (odds ratio per -3 mmHg, 1.06; 95% CI, 1.00 to 1.13; P = 0.023) were independently associated with postoperative pulmonary complications. Patients with postoperative pulmonary complications were more likely to be admitted to the intensive care unit (odds ratio, 12.5; 95% CI, 6.6 to 10.1; P < 0.001), had longer hospital length of stay (subhazard ratio, 0.43; 95% CI, 0.40 to 0.45), and higher in-hospital (subhazard ratio, 6.0; 95% CI, 4.1 to 9.0; P < 0.001) and 1-yr mortality (subhazard ratio, 2.65; 95% CI, 2.33 to 3.02; P < 0.001). CONCLUSIONS: In the study's population, decreased rather than increased tidal volume, decreased compliance, increased mechanical power, and decreased end-tidal carbon dioxide were independently associated with postoperative pulmonary complications.

Effect of incremental PEEP titration on postoperative pulmonary complications in patients undergoing emergency laparotomy: a randomized controlled trial.

Postoperative pulmonary complications (PPC) has a significant negative impact and are associated with increased length of hospital stay and cost of care. Emergency surgery is a well-established risk factor for PPC. Previous studies reported that personalized positive end-expiratory pressure (PEEP) might reduce postoperative atelectasis and postoperative pulmonary complications. N = 168 adult patients undergoing major emergency laparotomy under general anesthesia were recruited in this study. A minimum driving pressure based incremental PEEP titration was compared to a fixed PEEP of 5 cmH2O. The primary outcome was PPC up to postoperative day 7. The mean (standard deviation) of the recruited patients was 41.7(16.1)y, and 48.8% (82 of 168 patients) were female. The risk of PPC at postoperative day 7 was similar in both the study groups [Relative risk (RR) (95% Confidence interval, CI) 0.81 (0.58, 1.13); p = 0.25]. In addition, the incidence of intraoperative hypotension [p = 0.75], oxygen-free days at day 28 [p = 0.27], duration of postoperative hospital stay [p = 0.50], length of postoperative intensive care unit stay [p = 0.28], and in-hospital mortality [p = 0.38] were similar in two groups. Incidence of PPC was not reduced with the use of an individualized PEEP strategy based on lowest driving pressure. However, the incidence of hypotension and bradycardia was also not increased with titrated PEEP.Trial Registration: www.ctri.nic.in ; CTRI/2020/12/029765.

Dexmedetomidine improves pulmonary outcomes in thoracic surgery under one-lung ventilation: A meta-analysis.

INTRODUCTION: Dexmedetomidine improves intrapulmonary shunt in thoracic surgery and minimizes inflammatory response during one-lung ventilation (OLV). However, it is unclear whether such benefits translate into less postoperative pulmonary complications (PPCs). Our objective was to determine the impact of dexmedetomidine on the incidence of PPCs after thoracic surgery. METHODS: Major databases were used to identify randomized trials that compared dexmedetomidine versus placebo during thoracic surgery in terms of PPCs. Our primary outcome was atelectasis within 7 days after surgery. Other specific PPCs included hypoxemia, pneumonia, and acute respiratory distress syndrome (ARDS). Secondary outcome included intraoperative respiratory mechanics (respiratory compliance [Cdyn]) and postoperative lung function (forced expiratory volume [FEV1]). Random effects models were used to estimate odds ratios (OR). RESULTS: Twelve randomized trials, including 365 patients in the dexmedetomidine group and 359 in the placebo group, were analyzed in this meta-analysis. Patients in the dexmedetomidine group were less likely to develop postoperative atelectasis (2.3% vs 6.8%, OR 0.42, 95%CI 0.18-0.95, P = 0.04; low certainty) and hypoxemia (3.4% vs 11.7%, OR 0.26, 95%CI 0.10-0.68, P = 0.01; moderate certainty) compared to the placebo group. The incidence of postoperative pneumonia (3.2% vs 5.8%, OR 0.57, 95%CI 0.25-1.26, P = 0.17; moderate certainty) or ARDS (0.9% vs 3.5%, OR 0.39, 95%CI 0.07-2.08, P = 0.27; moderate certainty) was comparable between groups. Both intraoperative Cdyn and postoperative FEV1 were higher among patients that received dexmedetomidine with a mean difference of 4.42 mL/cmH2O (95%CI 3.13-5.72) and 0.27 L (95%CI 0.12-0.41), respectively. CONCLUSION: Dexmedetomidine administration during thoracic surgery may potentially reduce the risk of postoperative atelectasis and hypoxemia. However, current evidence is insufficient to demonstrate an effect on pneumonia or ARDS.

Dental aspiration in a pediatric patient: a case report.

Foreign body aspiration is relatively common in children, especially in children younger than 3 years, and it is associated with a high incidence and mortality rate. Because of impairments in swallowing, speech, and vision, more caution regarding foreign body aspiration is required in children with abnormal nervous system development. This report describes a clinically rare case involving a 6-year-old patient with delayed brain development and epilepsy who was found to have a tooth in the bronchus of the left lung through fiberoptic bronchoscopy. The tooth was successfully removed by an extraction procedure. A follow-up examination showed that the patient had a sequela of left lower lobe atelectasis. This case indicates that greater caution is necessary regarding foreign body aspiration, including dental aspiration, in patients with abnormal development of the nervous system.

[Perioperative Management for Air Leakage, Atelectasis, and Pneumonia in Patients Undergoing Lung Resection].

Thoracic surgeons often encounter postoperative air leakage, atelectasis, and pneumonia as common complications of lung resection. Mostly, those are managed and treated properly, which results in avoiding serious outcomes. However, some clinical conditions manifesting initially as common complications could become severe unless an early correct differential diagnosis is made. Regarding air leakage, we summarized intraoperative techniques for pulmonary fistula and pleurodesis as postoperative treatment. Concerning atelectasis, in addition to management for obstructive atelectasis due to bronchial secretion, we described the adaptive displacement of the middle lobe after right upper lobectomy and tips for diagnosis and management of bronchial kinking and/or lobar torsion of the middle lobe. Regarding postoperative pneumonia, we emphasized smoking cessation and overviewed standard management for chronic obstructive pulmonary disease by bronchodilator as preoperative management. Moreover, we summarized standard treatment for hospital-acquired pneumonia and emphasized the importance of differential diagnosis if the initial empiric antibiotic therapy failed because some interstitial pulmonary diseases, such as organizing pneumonia and drug-induced lung injury, may mimic bacterial pneumonia.

[Perioperative Strategy of Fluid and Nutrition in the Compromised Patients After Lung Resection].

The strategy for the administration of fluid and nutrition management after lung resection is not unusual, as compared to the other ordinal surgeries. However, it should be kept in mind that relative reduction in right ventricular function could occur following lung resection due to increased pulmonary vascular resistance. The surgical trauma such as pulmonary arterial clamp and lymphadenectomy as well as the removal of the lung, and perioperative factors such as single lung ventilation, could also increase pulmonary vascular resistance, all of which could be related to acute lung injury. Regarding the fluid management, excessive fluid administration could cause pulmonary edema, decreased alveolar gas permeability, atelectasis, and hypoxia, while restrictive fluid management could induce complication related to hypoperfusion. Since these adverse effects are highly associated with the main causes of morbidity and mortality particularly in the compromised patients, a proper assessment and monitoring of fluid balance (fluid optimization) would be required. In addition, along with the increasing number of the elderly patients, particular concerns must be given to the patients with the sarcopenia or frailty. The appropriate nutritional support following lung surgery is necessary to reduce surgical morbidity and morbidity especially for the malnourished and elderly patients.

Individualised positive end-expiratory pressure titrated intra-operatively by electrical impedance tomography optimises pulmonary mechanics and reduces postoperative atelectasis: A randomised controlled trial.

BACKGROUND: A protective intra-operative lung ventilation strategy has been widely recommended for laparoscopic surgery. However, there is no consensus regarding the optimal level of positive end-expiratory pressure (PEEP) and its effects during pneumoperitoneum. Electrical impedance tomography (EIT) has recently been introduced as a bedside tool to monitor lung ventilation in real-time. OBJECTIVE: We hypothesised that individually titrated EIT-PEEP adjusted to the surgical intervention would improve respiratory mechanics during and after surgery. DESIGN: Randomised controlled trial. SETTING: First Medical Centre of Chinese PLA General Hospital, Beijing. PATIENTS: Seventy-five patients undergoing robotic-assisted laparoscopic hepatobiliary and pancreatic surgery under general anaesthesia. INTERVENTIONS: Patients were randomly assigned 2 : 1 to individualised EIT-titrated PEEP (PEEPEIT; n = 50) or traditional PEEP 5 cmH2O (PEEP5 cmH2O; n = 25). The PEEPEIT group received individually titrated EIT-PEEP during pneumoperitoneum. The PEEP5 cmH2O group received PEEP of 5 cmH2O during pneumoperitoneum. MAIN OUTCOME MEASURES: The primary outcome was respiratory system compliance during laparoscopic surgery. Secondary outcomes were individualised PEEP levels, oxygenation, respiratory and haemodynamic status, and occurrence of postoperative pulmonary complications (PPCs) within 7 days. RESULTS: Compared with PEEP5 cmH2O, patients who received PEEPEIT had higher respiratory system compliance (mean values during surgery of 44.3 ±â€Š11.3 vs. 31.9 ±â€Š6.6, ml cmH2O-1; P < 0.001), lower driving pressure (11.5 ±â€Š2.1 vs. 14.0 ±â€Š2.4 cmH2O; P < 0.001), better oxygenation (mean PaO2/FiO2 427.5 ±â€Š28.6 vs. 366.8 ±â€Š36.4; P = 0.003), and less postoperative atelectasis (19.4 ±â€Š1.6 vs. 46.3 ±â€Š14.8 g of lung tissue mass; P = 0.003). Haemodynamic values did not differ significantly between the groups. No adverse effects were observed during surgery. CONCLUSION: Individualised PEEP by EIT may improve intra-operative pulmonary mechanics and oxygenation without impairing haemodynamic stability, and decrease postoperative atelectasis. TRIAL REGISTRATION: Chinese Clinical Trial Registry (www.chictr.org.cn) identifier: ChiCTR2100045166.

Evaluation of the Effect of Pressure-Controlled Ventilation-Volume Guaranteed Mode vs. Volume-Controlled Ventilation Mode on Atelectasis in Patients Undergoing Laparoscopic Surgery: A Randomized Controlled Clinical Trial.

Background and Objectives: Laparoscopic surgery, which results in less bleeding, less postoperative pain, and better cosmetic results, may affect the lung dynamics via the pneumoperitoneum. After laparoscopic surgery, atelectasis develops. The primary aim of the present study is to demonstrate the effects of two different ventilation modes on the development of atelectasis using lung ultrasound, and the secondary outcomes include the plateau pressure, peak inspiratory pressure, and compliance differences between the groups. Materials and Methods: In this study, 62 participants aged 18-75 years undergoing laparoscopic cholecystectomy were enrolled. The patients were randomly assigned into two groups: the volume-controlled ventilation (VCV) group (group V) or the pressure-controlled-volume guaranteed ventilation (PCV-VG) group (group PV). The lung ultrasound score (LUS) was obtained thrice: prior to induction (T1), upon the patient's initial arrival in the recovery room (T2), and just before departing the recovery unit (T3). The hemodynamic data and mechanical ventilation parameters were recorded at different times intraoperatively. Results: The LUS score was similar between the groups at all the times. The change in the LUS score of the right lower anterior chest was statistically higher in the VCV group than the PCV group. The peak inspiratory pressure (PIP) was found to be statistically higher in the V group than the PV group five minutes after induction (T5) (20.84 ± 4.32 p = 0.021). The plateau pressure was found to be higher in the V group than the PV group at all times (after induction (Tind) 17.29 ± 5.53 p = 0.004, (T5) 17.77 ± 4.89 p = 0.001, after pneumoperitoneum (TPP) 19.71 ± 4.28 p = 0.002). Compliance was found to be statistically higher in the PV group than the V group at all times ((Tind) 48.87 ± 15.37 p = 0.011, (T5) 47.94 ± 13.71 p = 0.043, (TPP) 35.65 ± 6.90 p = 0.004). Before and after the pneumoperitoneum, the compliance was determined to be lower in the V group than the PV group, respectively (40.68 ± 13.91 p = 0.043, 30.77 ± 5.73 p = 0.004). Conclusions: LUS score was similar between groups at all times. The PCV-VG mode was superior to the VCV mode in providing optimal ventilatory pressures and maintaining high dynamic compliance in patients undergoing laparoscopic abdominal surgery.