Limiting Overdistention or Collapse When Mechanically Ventilating Injured Lungs: A Randomized Study in a Porcine Model.

Rationale: It is unknown whether preventing overdistention or collapse is more important when titrating positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS). Objectives: To compare PEEP targeting minimal overdistention or minimal collapse or using a compromise between collapse and overdistention in a randomized trial and to assess the impact on respiratory mechanics, gas exchange, inflammation, and hemodynamics. Methods: In a porcine model of ARDS, lung collapse and overdistention were estimated using electrical impedance tomography during a decremental PEEP titration. Pigs were randomized to three groups and ventilated for 12 hours: PEEP set at ⩽3% of overdistention (low overdistention), ⩽3% of collapse (low collapse), and the crossing point of collapse and overdistention. Measurements and Main Results: Thirty-six pigs (12 per group) were included. Median (interquartile range) values of PEEP were 7 (6-8), 11 (10-11), and 15 (12-16) cm H2O in the three groups (P < 0.001). With low overdistension, 6 (50%) pigs died, whereas survival was 100% in both other groups. Cause of death was hemodynamic in nature, with high transpulmonary vascular gradient and high epinephrine requirements. Compared with the other groups, pigs surviving with low overdistension had worse respiratory mechanics and gas exchange during the entire protocol. Minimal differences existed between crossing-point and low-collapse animals in physiological parameters, but postmortem alveolar density was more homogeneous in the crossing-point group. Inflammatory markers were not significantly different. Conclusions: PEEP to minimize overdistention resulted in high mortality in an animal model of ARDS. Minimizing collapse or choosing a compromise between collapse and overdistention may result in less lung injury, with potential benefits of the compromise approach.

Influence of Fractional Inspired Oxygen Tension on Lung Perfusion Distribution, Regional Ventilation, and Lung Volume during Mechanical Ventilation of Supine Healthy Swine.

BACKGROUND: Lower fractional inspired oxygen tension (Fio2) during general anesthesia can reduce lung atelectasis. The objectives are to evaluate the effect of two Fio2 (0.4 and 1) during low positive end-expiratory pressure (PEEP) ventilation over lung perfusion distribution, volume, and regional ventilation. These variables were evaluated at two PEEP levels and unilateral lung atelectasis. METHODS: In this exploratory study, 10 healthy female piglets (32.3 ± 3.4 kg) underwent mechanical ventilation in two atelectasis models: (1) bilateral gravitational atelectasis (n = 6), induced by changes in PEEP and Fio2 in three combinations: high PEEP with low Fio2 (Fio2 = 0.4), zero PEEP (PEEP0) with low Fio2 (Fio2 = 0.4), and PEEP0 with high Fio2 (Fio2 = 1); and (2) unilateral atelectasis (n = 6), induced by left bronchial occlusion, with the left lung aerated (Fio2 = 0.21) and low aerated (Fio2 = 1; n = 5 for this step). Measurements were conducted after 10 min in each step, encompassing assessment of respiratory mechanics, oxygenation, and hemodynamics; lung ventilation and perfusion by electrical impedance tomography; and lung aeration and perfusion by computed tomography. RESULTS: During bilateral gravitational atelectasis, PEEP reduction increased atelectasis in dorsal regions, decreased respiratory compliance, and distributed lung ventilation to ventral regions with a parallel shift of perfusion to the same areas. With PEEP0, there were no differences between low and high Fio2 in respiratory compliance (23.9 ± 6.5 ml/cm H2O vs. 21.9 ± 5.0; P = 0.441), regional ventilation, and regional perfusion, despite higher lung collapse (18.6 ± 7.6% vs. 32.7 ± 14.5%; P = 0.045) with high Fio2. During unilateral lung atelectasis, the deaerated lung had a lower shunt (19.3 ± 3.6% vs. 25.3 ± 5.5%; P = 0.045) and lower computed tomography perfusion to the left lung (8.8 ± 1.8% vs. 23.8 ± 7.1%; P = 0.007). CONCLUSIONS: PEEP0 with low Fio2, compared with high Fio2, did not produce significant changes in respiratory system compliance, regional lung ventilation, and perfusion despite significantly lower lung collapse. After left bronchial occlusion, the shrinkage of the parenchyma with Fio2 = 1 enhanced hypoxic pulmonary vasoconstriction, reducing intrapulmonary shunt and perfusion of the nonventilated areas.

[Efficacy of bronchoalveolar lavage combined with prone positioning in children with Mycoplasma pneumoniae pneumonia and atelectasis: a prospective randomized controlled study]. / æ”¯æ°”ç®¡è‚ºæ³¡çŒæ´—è”åˆä¿¯å§ä½æ²»ç–—å„¿ç«¥è‚ºç‚Žæ”¯åŽŸä½“è‚ºç‚Žä¼´è‚ºä¸å¼ ç–—æ•ˆçš„å‰çž»æ€§éšæœºå¯¹ç §ç ”ç©¶.

OBJECTIVES: To study the efficacy of bronchoalveolar lavage (BAL) combined with prone positioning in children with Mycoplasma pneumoniae pneumonia (MPP) and atelectasis and its effect on pulmonary function. METHODS: A prospective study was conducted on 94 children with MPP and atelectasis who were hospitalized in Ordos Central Hospital of Inner Mongolia from November 2020 to May 2023. The children were randomly divided into a treatment group and a control group, with 47 children in each group. The children in the treatment group were given conventional treatment, BAL, and prone positioning, and those in the control group were given conventional treatment and BAL. The two groups were compared in terms of fever, pulmonary signs, length of hospital stay, lung recruitment, and improvement in pulmonary function. RESULTS: Compared with the control group, the treatment group had significantly shorter time to improvement in pulmonary signs and length of hospital stay and a significantly higher rate of lung recruitment on day 7 of hospitalization, on the day of discharge, and at 1 week after discharge (P<0.05). Compared with the control group, the treatment group had significantly higher levels of forced vital capacity (FVC) as a percentage of the predicted value, forced expiratory volume (FEV) in 1 second as a percentage of the predicted value, ratio of FEV in 1 second to FVC, forced expiratory flow at 50% of FVC as a percentage of the predicted value, forced expiratory flow at 75% of FVC as a percentage of the predicted value, and maximal mid-expiratory flow as a percentage of the predicted value on the day of discharge and at 1 week after discharge (P<0.05). There was no significant difference in the time for body temperature to return to normal between the two groups (P>0.05). CONCLUSIONS: In the treatment of children with MPP and atelectasis, BAL combined with prone positioning can help to shorten the time to improvement in pulmonary signs and the length of hospital stay and promote lung recruitment and improvement in pulmonary function.

Effect of Active Physiotherapy With Positive Airway Pressure on Pulmonary Atelectasis After Cardiac Surgery: A Randomized Controlled Study.

OBJECTIVES: The authors investigated the effect of active work with positive airway pressure (PAP) in addition to chest physiotherapy (CP) on pulmonary atelectasis (PA) in patients undergoing cardiac surgery with cardiopulmonary bypass. DESIGN: A randomized controlled study. SETTING: At a single-center tertiary hospital. PARTICIPANTS: Eighty adult patients undergoing cardiac surgery (coronary artery bypass grafting, valve surgery, or both), and presenting with PA after tracheal extubation on postoperative days 1 or 2, were randomized from November 2014 to September 2016. INTERVENTION: Three days of CP, twice daily, associated with active work with PAP effect (intervention group) versus CP alone (control group). Pulmonary atelectasis was assessed by using the radiologic atelectasis score (RAS) measured from daily chest x-rays. All radiographs were reviewed blindly. MEASUREMENTS AND MAIN RESULTS: Among included patients, 79 (99%) completed the trial. The primary outcome was mean RAS on day 2 after inclusion. It was significantly lower in the intervention group (mean difference and 95% CI: -1.1 [-1.6 to -0.6], p < 0.001). The secondary outcomes were the sniff nasal inspiratory pressure measured before and after CP and clinical variables. Sniff nasal inspiratory pressure was significantly higher in the intervention group on day 2 (7.7 [3.0-12.5] cmH2O, p = 0.002). The respiratory rate was lower in the intervention group (-3.2 [95% CI -4.8 to -1.6] breaths/min, p < 0.001) on day 2. No differences were found between the 2 groups for percutaneous oxygen saturation/oxygen requirement ratio, heart rate, pain, and dyspnea scores. CONCLUSIONS: Active work with the PAP effect, combined with CP, significantly decreased the RAS of patients undergoing cardiac surgery after 2 days of CP, with no differences observed in clinically relevant parameters.

Variable ventilation versus stepwise lung recruitment manoeuvres for lung recruitment: A comparative study in an experimental model of atelectasis.

BACKGROUND: Variable ventilation recruits alveoli in atelectatic lungs, but it is unknown how it compares with conventional recruitment manoeuvres. OBJECTIVES: To test whether mechanical ventilation with variable tidal volumes and conventional recruitment manoeuvres have comparable effects on lung function. DESIGN: Randomised crossover study. SETTING: University hospital research facility. ANIMALS: Eleven juvenile mechanically ventilated pigs with atelectasis created by saline lung lavage. INTERVENTIONS: Lung recruitment was performed using two strategies, both with an individualised optimal positive-end expiratory pressure (PEEP) associated with the best respiratory system elastance during a decremental PEEP trial: conventional recruitment manoeuvres (stepwise increase of PEEP) in pressure-controlled mode) followed by 50 min of volume-controlled ventilation (VCV) with constant tidal volume, and variable ventilation, consisting of 50 min of VCV with random variation in tidal volume. MAIN OUTCOME MEASURES: Before and 50 min after each recruitment manoeuvre strategy, lung aeration was assessed by computed tomography, and relative lung perfusion and ventilation (0% = dorsal, 100% = ventral) were determined by electrical impedance tomography. RESULTS: After 50 min, variable ventilation and stepwise recruitment manoeuvres decreased the relative mass of poorly and nonaerated lung tissue (percent lung mass: 35.3 ±â€Š6.2 versus 34.2 ±â€Š6.6, P  = 0.303); reduced poorly aerated lung mass compared with baseline (-3.5 ±â€Š4.0%, P  = 0.016, and -5.2 ±â€Š2.8%, P  < 0.001, respectively), and reduced nonaerated lung mass compared with baseline (-7.2 ±â€Š2.5%, P  < 0.001; and -4.7 ±â€Š2.8%, P  < 0.001 respectively), while the distribution of relative perfusion was barely affected (variable ventilation: -0.8 ±â€Š1.1%, P  = 0.044; stepwise recruitment manoeuvres: -0.4 ±â€Š0.9%, P  = 0.167). Compared with baseline, variable ventilation and stepwise recruitment manoeuvres increased Pa O 2 (172 ±â€Š85mmHg, P  = 0.001; and 213 ±â€Š73 mmHg, P  < 0.001, respectively), reduced Pa CO 2 (-9.6 ±â€Š8.1 mmHg, P  = 0.003; and -6.7 ±â€Š4.6 mmHg, P  < 0.001, respectively), and decreased elastance (-11.4 ±â€Š6.3 cmH 2 O, P  < 0.001; and -14.1 ±â€Š3.3 cmH 2 O, P  < 0.001, respectively). Mean arterial pressure decreased during stepwise recruitment manoeuvres (-24 ±â€Š8 mmHg, P  = 0.006), but not variable ventilation. CONCLUSION: In this model of lung atelectasis, variable ventilation and stepwise recruitment manoeuvres effectively recruited lungs, but only variable ventilation did not adversely affect haemodynamics. TRIAL REGISTRATION: This study was registered and approved by Landesdirektion Dresden, Germany (DD24-5131/354/64).

[Recurrent atelectasis in an infant : about one case of false-negative newborn screening for cystic fibrosis]. / Atélectasie récidivante chez un nourrisson : à propos d'un cas de faux-négatif du dépistage néonatal pour la mucoviscidose.

In infants as well as in older children, persistent or recurrent atelectasis remains a classic indication for sweat testing, even if neonatal screening for cystic fibrosis has been considered normal. Atelectasis is a common complication of cystic fibrosis. Yet, it has rarely been reported in infants. In cystic fibrosis, chronic atelectasis worsens the prognosis, especially when involving a lower lobe. Therefore, early and effective intervention is required. Antibiotic therapy, intensive chest physiotherapy together with inhaled mucolytics often allow to relieve bronchial obstruction but bronchoscopy with local aspiration and Dornase alpha instillation is sometimes necessary. In a two-month-old infant, we describe here the first reported case of false-negative cystic fibrosis newborn screening in Belgium.

Chez le nourrisson comme chez l'enfant plus âgé, une atélectasie persistante ou récidivante reste une indication classique de test à la sueur, même si le dépistage néonatal de la mucoviscidose a été considéré comme normal. Rarement rapportées chez le nourrisson, les atélectasies sont une complication commune de la mucoviscidose. Dans cette affection, l'atélectasie chronique d'un territoire péjore le pronostic, en particulier si elle concerne un lobe inférieur. Une intervention précoce et efficace est donc requise. Antibiothérapie, kinésithérapie respiratoire intensive et recours aux fluidifiants par voie de nébulisation suffisent souvent à lever l'obstruction bronchique, mais une endoscopie avec aspiration locale et instillation de dornase alpha est parfois nécessaire. Chez un nourrisson de 2 mois, nous rapportons ici le premier cas de faux-négatif du programme belge de dépistage néonatal de la mucoviscidose.

[Risk factors for pulmonary atelectasis in adults with tracheobronchial tuberculosis].

Objective: To investigate the risk factors for pulmonary atelectasis in adults with tracheobronchial tuberculosis(TBTB). Methods: Clinical data of adult patients (≥18 years old) with TBTB from February 2018 to December 2021 in Public Health Clinical Center of Chengdu were retrospectively analyzed. A total of 258 patients were included, with a male to female ratio of 1∶1.43. The median age was 31(24, 48) years. Clinical data including clinical characteristics, previous misdiagnoses/missed diagnoses before admission, pulmonary atelectasis, the time from symptom onset to atelectasis and bronchoscopy, bronchoscopy and interventional treatment were collected according to the inclusion and exclusion criteria. Patients were divided into two groups according to whether they had pulmonary atelectasis. Differences between the two groups were compared. Binary logistic regression was used to analyze the risk factors for pulmonary atelectasis. Results: The prevalence of pulmonary atelectasis was 14.7%, which was most common in the left upper lobe (26.3%). The median time from symptom onset to atelectasis was 130.50(29.75,358.50)d, and the median time from atelectasis to bronchoscopy was 5(3,7)d. The median age, the proportion of misdiagnosis of TBTB before admission, and the time from symptom onset to bronchoscopy in the atelectasis group were higher than those without atelectasis, and the proportion of receiving bronchoscopy examination and interventional therapy previously, and the proportion of pulmonary cavities were lower than those without atelectasis (all P<0.05). The proportions of cicatrices stricture type and lumen occlusion type in the atelectasis group were higher than those without atelectasis, while the proportions of inflammatory infiltration type and ulceration necrosis type were lower than those without atelectasis (all P<0.05). Older age (OR=1.036, 95%CI: 1.012-1.061), previous misdiagnosis(OR=2.759, 95%CI: 1.100-6.922), longer time from symptom onset to bronchoscopy examination (OR=1.002, 95%CI: 1.000-1.005) and cicatrices stricture type (OR=2.989, 95%CI: 1.279-6.985) were independent risk factors for pulmonary atelectasis in adults with TBTB (all P<0.05). Of the patients with atelectasis who underwent bronchoscopy interventional therapy, 86.7% had lung reexpansion or partial reexpansion. Conclusions: The prevalence of pulmonary atelectasis is 14.7% in adult patients with TBTB. The most common site of atelectasis is left upper lobe. The TBTB type of lumen occlusion is complicated by pulmonary atelectasis in 100% of cases. Being older, misdiagnosed as other diseases, longer time from onset of symptoms to bronchoscopy examination, and being the cicatrices stricture type are factors for developing pulmonary atelectasis. Early diagnosis and treatment are needed to reduce the incidence of pulmonary atelectasis and increase the rate of pulmonary reexpansion.

Perioperative Pulmonary Atelectasis: Part I. Biology and Mechanisms.

Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface tension overcome expanding forces from alveolar pressure and parenchymal tethering. Atelectasis impairs blood oxygenation and reduces lung compliance. It is increasingly recognized that it can also induce local tissue biologic responses, such as inflammation, local immune dysfunction, and damage of the alveolar-capillary barrier, with potential loss of lung fluid clearance, increased lung protein permeability, and susceptibility to infection, factors that can initiate or exaggerate lung injury. Mechanical ventilation of a heterogeneously aerated lung (e.g., in the presence of atelectatic lung tissue) involves biomechanical processes that may precipitate further lung damage: concentration of mechanical forces, propagation of gas-liquid interfaces, and remote overdistension. Knowledge of such pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management.

Perioperative Pulmonary Atelectasis: Part II. Clinical Implications.

The development of pulmonary atelectasis is common in the surgical patient. Pulmonary atelectasis can cause various degrees of gas exchange and respiratory mechanics impairment during and after surgery. In its most serious presentations, lung collapse could contribute to postoperative respiratory insufficiency, pneumonia, and worse overall clinical outcomes. A specific risk assessment is critical to allow clinicians to optimally choose the anesthetic technique, prepare appropriate monitoring, adapt the perioperative plan, and ensure the patient's safety. Bedside diagnosis and management have benefited from recent imaging advancements such as lung ultrasound and electrical impedance tomography, and monitoring such as esophageal manometry. Therapeutic management includes a broad range of interventions aimed at promoting lung recruitment. During general anesthesia, these strategies have consistently demonstrated their effectiveness in improving intraoperative oxygenation and respiratory compliance. Yet these same intraoperative strategies may fail to affect additional postoperative pulmonary outcomes. Specific attention to the postoperative period may be key for such outcome impact of lung expansion. Interventions such as noninvasive positive pressure ventilatory support may be beneficial in specific patients at high risk for pulmonary atelectasis (e.g., obese) or those with clinical presentations consistent with lung collapse (e.g., postoperative hypoxemia after abdominal and cardiothoracic surgeries). Preoperative interventions may open new opportunities to minimize perioperative lung collapse and prevent pulmonary complications. Knowledge of pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should provide the basis for current practice and help to stratify and match the intensity of selected interventions to clinical conditions.

Impact of airway and a standardized recruitment maneuver on CT chest imaging quality in a pediatric population: A retrospective review.

INTRODUCTION: When performing computerized tomography chest imaging in children, obtaining high quality, motion-free images is important in the accurate diagnosis of underlying pathology. General anesthesia is associated with the development of atelectasis, which can impair accurate diagnosis by obscuring or altering the appearance of the lung parenchyma or airways. Recruitment maneuvers, performed by anesthesiologists, can be used to effectively re-expand atelectatic lung. METHODS: The computerized tomography chest imaging in 44 children aged between 2 months and 7 years, undergoing serial imaging for monitoring of cystic fibrosis, were reviewed and graded for atelectasis. The first scan performed on each child was performed with a supraglottic airway device and a non-standardized recruitment maneuver. The second scan on each child was performed with a cuffed endotracheal tube and a standardized recruitment maneuver. RESULTS: When a supraglottic airway device and a non-standardized recruitment maneuver were used, 77% of patients demonstrated atelectasis of any degree on their computerized tomography chest imaging, compared with only 39% when a cuffed endotracheal tube and standardized recruitment maneuver were used. The percentage of computerized tomography chest scans that were scored acceptable (with either a total combined lung atelectasis score of 0 or 1) improved from 37% to 75% when a cuffed endotracheal tube and standardized recruitment maneuver were used. In particular, the mean atelectasis score for both lungs improved from 2.91 (SD ± 2.6) to 1.11 (SD ± 1.9), with a mean difference of 1.8 (95% CI 0.82-2.77; p: .0004). CONCLUSION: The use of a cuffed endotracheal tube and a standardized recruitment maneuver is an effective way to reduce atelectasis as a result of general anesthesia. Anesthesiologists can actively contribute toward improved image quality through their choice of airway and recruitment maneuver.

Targeted lateral positioning decreases lung collapse and overdistension in COVID-19-associated ARDS.

BACKGROUND: Among the challenges for personalizing the management of mechanically ventilated patients with coronavirus disease (COVID-19)-associated acute respiratory distress syndrome (ARDS) are the effects of different positive end-expiratory pressure (PEEP) levels and body positions in regional lung mechanics. Right-left lung aeration asymmetry and poorly recruitable lungs with increased recruitability with alternating body position between supine and prone have been reported. However, real-time effects of changing body position and PEEP on regional overdistension and collapse, in individual patients, remain largely unknown and not timely monitored. The aim of this study was to individualize PEEP and body positioning in order to reduce the mechanisms of ventilator-induced lung injury: collapse and overdistension. METHODS: We here report a series of five consecutive mechanically ventilated patients with COVID-19-associated ARDS in which sixteen decremental PEEP titrations were performed in the first days of mechanical ventilation (8 titration pairs: supine position immediately followed by 30° targeted lateral position). The choice of lateral tilt was based on X-Ray. This targeted lateral position strategy was defined by selecting the less aerated lung to be positioned up and the more aerated lung to be positioned down. For each PEEP level, global and regional collapse and overdistension maps and percentages were measured by electrical impedance tomography. Additionally, we present the incidence of lateral asymmetry in a cohort of forty-four patients. RESULTS: The targeted lateral position strategy resulted in significantly smaller amounts of overdistension and collapse when compared with the supine one: less collapse along the PEEP titration was found within the left lung in targeted lateral (P = 0.014); and less overdistension along the PEEP titration was found within the right lung in targeted lateral (P = 0.005). Regarding collapse within the right lung and overdistension within the left lung: no differences were found for position. In the cohort of forty-four patients, ventilation inequality of > 65/35% was observed in 15% of cases. CONCLUSIONS: Targeted lateral positioning with bedside personalized PEEP provided a selective attenuation of overdistension and collapse in mechanically ventilated patients with COVID-19-associated ARDS and right-left lung aeration/ventilation asymmetry. TRIAL REGISTRATION: Trial registration number: NCT04460859.

Mechanical Ventilation Redistributes Blood to Poorly Ventilated Areas in Experimental Lung Injury.

OBJECTIVES: Determine the intra-tidal regional gas and blood volume distributions at different levels of atelectasis in experimental lung injury. Test the hypotheses that pulmonary aeration and blood volume matching is reduced during inspiration in the setting of minimal tidal recruitment/derecruitment and that this mismatching is an important determinant of hypoxemia. DESIGN: Preclinical study. SETTING: Research laboratory. SUBJECTS: Seven anesthetized pigs 28.7 kg (SD, 2.1 kg). INTERVENTIONS: All animals received a saline-lavage surfactant depletion lung injury model. Positive end-expiratory pressure was varied between 0 and 20 cm H2O to induce different levels of atelectasis. MEASUREMENTS AND MAIN RESULTS: Dynamic dual-energy CT images of a juxtadiaphragmatic slice were obtained, gas and blood volume fractions within three gravitational regions calculated and normalized to lung tissue mass (normalized gas volume and normalized blood volume, respectively). Ventilatory conditions were grouped based upon the fractional atelectatic mass in expiration (< 20%, 20-40%, and ≥ 40%). Tidal recruitment/derecruitment with fractional atelectatic mass in expiration greater than or equal to 40% was less than 7% of lung mass. In this group, inspiration-related increase in normalized gas volume was greater in the nondependent (818 µL/g [95% CI, 729-908 µL/g]) than the dependent region (149 µL/g [120-178 µL/g]). Normalized blood volume decreased in inspiration in the nondependent region (29 µL/g [12-46 µL/g]) and increased in the dependent region (39 µL/g [30-48 µL/g]). Inspiration-related changes in normalized gas volume and normalized blood volume were negatively correlated in fractional atelectatic mass in expiration greater than or equal to 40% and 20-40% groups (r = 0.56 and 0.40), but not in fractional atelectatic mass in expiration less than 20% group (r = 0.01). Both the increase in normalized blood volume in the dependent region and fractional atelectatic mass in expiration negatively correlated with PaO2/FIO2 ratio (ρ = -0.77 and -0.93, respectively). CONCLUSIONS: In experimental atelectasis with minimal tidal recruitment/derecruitment, mechanical inspiratory breaths redistributed blood volume away from well-ventilated areas, worsening PaO2/FIO2.

Adaptive radiotherapy in locally advanced esophageal cancer with atelectasis: a case report.

BACKGROUND: To the best of our knowledge, no study has reported mediastinal shift accompanied with obstructive atelectasis due to bulky primary esophageal tumor components treated with adaptive radiotherapy and concurrent chemotherapy. CASE PRESENTATION: Here we report the case of a 65-year-old male patient diagnosed with locally advanced thoracic esophageal squamous cell cancer, clinical T4bN1M0, stage IVA. Bronchoscopy and computed tomography (CT) revealed an almost complete obstruction of the lumen of the left bronchus due to compression by bulky primary esophageal tumor components. On admission, the patient presented with dyspnea and decreased arterial oxygen saturation. Chest radiography and CT on admission revealed mediastinal shift with left atelectasis, as opposed to findings from the chest radiography performed 26 days before admission. Because of the patient's overall good condition, we recommended definitive chemoradiotherapy instead of palliative bronchial stent placement. After obtaining the patient's consent, chemoradiotherapy was initiated on the following day and it comprised three-dimensional conformal radiotherapy with 60 Gy in 30 fractions with concurrent administration of cisplatin and 5-fluorouracil. During chemoradiotherapy, tumor location was monitored with cone-beam CT and chest radiography. Chemoradiotherapy on day 8 revealed no evidence of the mediastinal shift. CT simulation was reperformed to adjust the radiotherapy fields to account for geometrical changes induced by the absence of the mediastinal shift. Subsequently, the mediastinal shift and bronchial obstruction did not recur during the course of chemoradiotherapy. The patient completed the planned radiotherapy with concurrent and adjuvant chemotherapy, and no non-hematological grade ≥ 3 adverse events were observed. Complete response was confirmed 7 months after initiating chemoradiotherapy. Currently, no disease recurrence, dysphagia, or respiratory symptoms have been reported at 13 months after initiating chemoradiotherapy. CONCLUSIONS: In this study, a bulky primary esophageal tumor caused mediastinal shift due to ipsilateral bronchial obstruction. The close follow-up for monitoring resolution of the mediastinal shift during the course of chemoradiotherapy enabled adequate dose delivery to targets, thus reflecting the geometrical changes induced by the absence of the mediastinal shift. Adaptive radiotherapy technique was crucial for favorable patient outcomes in this challenging clinical situation.

The fraction of nitrous oxide in oxygen for facilitating lung collapse during one-lung ventilation with double lumen tube.

BACKGROUND: The ideal fraction of nitrous oxide (N2O) in oxygen (O2) for rapid lung collapse remains unclear. Accordingly, this prospective trial aimed to determine the 50% effective concentration (EC50) and 95% effective concentration (EC95) of N2O in O2 for rapid lung collapse. METHODS: This study included 38 consecutive patients undergoing video-assisted thoracoscopic surgery (VATS). The lung collapse score (LCS) of each patient during one-lung ventilation was evaluated by the same surgeon. The first patient received 30% N2O in O2, and the subsequent N2O fraction in O2 was determined by the LCS of the previous patient using the Dixon up-and-down method. The testing interval was set at 10%, and the lowest concentration was 10% (10, 20, 30, 40%, or 50%). The EC50 and EC95 of N2O in O2 for rapid lung collapse were analyzed using a probit test. RESULTS: According to the up-and-down method, the N2O fraction in O2 at which all patients exhibited successful lung collapse was 50%. The EC50 and EC95 of N2O in O2 for rapid lung collapse were 27.7% (95% confidence interval 19.9-35.7%) and 48.7% (95% confidence interval 39.0-96.3%), respectively. CONCLUSIONS: In patients undergoing VATS, the EC50 and EC95 of N2O in O2 for rapid lung collapse were 27.7 and 48.7%, respectively. TRIAL REGISTRATION: http://www.chictr.org/cn/ Identifier ChiCTR19 00021474 , registered on 22 February 2019.

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

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 cmH2O 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 cmH2O 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. TRIAL REGISTRATION: Clinical Research Information Service Identifier: KCT0003746.

[Diagnosis and treatment value of bedside pulmonary ultrasound for atelectasis in patients after cardiac surgery].

Objective: To investigate the value of bedside pulmonary ultrasound in the diagnosis and treatment of atelectasis in patients after cardiac surgery. Methods: A total of 45 patients developed respiratory failure within 1 week after cardiovascular surgery from April 2017 to April 2018 were enrolled in this study. Among them, 27 were male and 18 were female, mean age was (47±5) years. The postoperative pulmonary ultrasound and chest CT findings were collected, and the consistency, efficacy evaluation, timeliness and safety value of pulmonary ultrasound and chest CT diagnosis were compared. The consistency of the two diagnostic methods was checked based on the Kappa consistency test. Results: A total of 87 foci of atelectasis were diagnosed in 45 patients, including 29 foci of complete atelectasis and 58 foci of incomplete atelectasis. Thoracic CT examination confirmed 44 cases of atelectasis (positive rate 97.8%), and 42 cases (93.3%) were found with atelectasis with ultrasound test. The two methods were consistent in the diagnosis of atelectasis (Kappa value was 0.741, P<0.05). In the evaluation of the atelectasis, the results of the two examination methods were completely consistent, and the pulmonary ultrasound couldcheck the lung recruitment in real time. Ultrasound examination after lung recruitment showed that the total ventilation score of 42 patients decreased significantly when compared with that before treatment ((18.3±3.6) vs (26.6±3.8), t=10.229, P<0.05). There was no significant difference in the safety between the two examination methods. The time the bedside pulmonary ultrasound used was significantly shorter than that in the chest CT. Conclusions: The accuracy of bedside pulmonary ultrasound in assessing atelectasis after cardiovascular surgery is consistent with chest CT, it brings dynamic monitoring of lung status and assessment of lung recruitment by changes in lung ventilation scores. The inspection takes a short time and is worth promoting.

Cough and airway clearance in Duchenne muscular dystrophy.

People with Duchenne muscular dystrophy (DMD), develop a respiratory muscle weakness that results in weakened cough, airway clearance impairment and over time respiratory failure and death. Assessment of cough effectiveness through vital capacity, peak cough flow and maximal inspiratory and expiratory pressures has been used to identify the optimal timing of cough augmentation techniques initiation. The choice of therapies depends on physician knowledge, and patient/care giver abilities. The purpose of this review is to clarify mechanisms of action, benefits and disadvantages of available techniques, such as manual cough-assisting manoeuvres, glossopharyngeal breathing, air stacking by resuscitator bag or by volume-cycle ventilator, and mechanical insufflator-exsufflator. Mechanisms of mucus mobilization, like intrapulmonary percussive ventilation, may have a therapeutic role in the case of persistent atelectasis. It is also crucial to recognize the initial phase of an acute respiratory exacerbation, increase the use of these techniques which may reduce morbidity and mortality.

Modified Lung Ultrasound Examinations in Assessment and Monitoring of Positive End-Expiratory Pressure-Induced Lung Reaeration in Young Children With Congenital Heart Disease Under General Anesthesia.

OBJECTIVES: Lung ultrasound can reliably diagnose pulmonary atelectasis. The object of this study is to determine the most efficient region to assess changes in atelectasis in children with congenital heart disease under general anesthesia. DESIGN: Randomized controlled trial. SETTING: Operating room at university-affiliated children's hospital. PATIENTS: Children between 3 months and 3 years old, scheduled for elective congenital heart disease surgery under general anesthesia. INTERVENTIONS: Forty children with congenital heart disease were randomly allocated to either a 5 cm H2O positive end-expiratory pressure group or a standard therapy control group. MEASUREMENTS AND MAIN RESULTS: Preoperative lung ultrasound was performed twice in each patient-after 1 and 15 minutes of mechanical ventilation. Atelectatic areas and B-lines were compared between two examinations. Different ultrasound regions were evaluated using Bland-Altman plots. The occurrence rate of atelectasis was much higher in inferoposterior lung regions (Scans 4-6) than in anterior and lateral regions (Scans 1-3). The median (interquartile range) lung ultrasound scores were lower in the positive end-expiratory pressure group than in the control group after treatment: 8 (3.3-9.8) versus 13 (8.3-17.5; p < 0.001). The atelectatic area was significantly decreased after treatment in the positive end-expiratory pressure group: 128 mm (34.5.5-213.3 mm) versus 49.5 mm (5.3-75.5 mm; p < 0.001). Bland-Altman plots revealed concordance between measurements in Scans 1-6 and those in Scans 4-6. In the posterior axillary line regions, changes in atelectatic area were significantly larger in the positive end-expiratory pressure group than in the control group (p = 0.03, 0.007, and 0.018). CONCLUSIONS: Lung ultrasound in inferoposterior lung regions may be more likely to reflect changes in atelectasis and save examination time; 5 cm H2O positive end-expiratory pressure may be useful in lung reaeration and can reduce, but not eliminate, atelectasis in children with congenital heart disease.

Expiratory Central Airway Collapse in Adults: Corrective Treatment (Part 2).

Corrective treatment of expiratory central airway collapse (ECAC) consists of placement of airway stents or tracheobronchoplasty (TBP). The indication for corrective treatment is severe central airway collapse (>90 %), and severe symptoms that cause decline in quality of life. Patients are selected to undergo a trial of tracheal "Y" stent placement. If symptoms improve (positive trial) they undergo a TBP, provided they are good surgical candidates. Patients who are considered poor surgical candidates because of the severity of comorbidities can be offered permanent stenting to palliate symptoms. The anesthetic management of airway stent placement and TBP is complex. This article reviews the medical management and corrective treatment of ECAC, anesthetic management of airway stent placement, and considerations during TBP.

Effect of Intraoperative High Positive End-Expiratory Pressure (PEEP) With Recruitment Maneuvers vs Low PEEP on Postoperative Pulmonary Complications in Obese Patients: A Randomized Clinical Trial.

Importance: An intraoperative higher level of positive end-expiratory positive pressure (PEEP) with alveolar recruitment maneuvers improves respiratory function in obese patients undergoing surgery, but the effect on clinical outcomes is uncertain. Objective: To determine whether a higher level of PEEP with alveolar recruitment maneuvers decreases postoperative pulmonary complications in obese patients undergoing surgery compared with a lower level of PEEP. Design, Setting, and Participants: Randomized clinical trial of 2013 adults with body mass indices of 35 or greater and substantial risk for postoperative pulmonary complications who were undergoing noncardiac, nonneurological surgery under general anesthesia. The trial was conducted at 77 sites in 23 countries from July 2014-February 2018; final follow-up: May 2018. Interventions: Patients were randomized to the high level of PEEP group (n = 989), consisting of a PEEP level of 12 cm H2O with alveolar recruitment maneuvers (a stepwise increase of tidal volume and eventually PEEP) or to the low level of PEEP group (n = 987), consisting of a PEEP level of 4 cm H2O. All patients received volume-controlled ventilation with a tidal volume of 7 mL/kg of predicted body weight. Main Outcomes and Measures: The primary outcome was a composite of pulmonary complications within the first 5 postoperative days, including respiratory failure, acute respiratory distress syndrome, bronchospasm, new pulmonary infiltrates, pulmonary infection, aspiration pneumonitis, pleural effusion, atelectasis, cardiopulmonary edema, and pneumothorax. Among the 9 prespecified secondary outcomes, 3 were intraoperative complications, including hypoxemia (oxygen desaturation with Spo2 ≤92% for >1 minute). Results: Among 2013 adults who were randomized, 1976 (98.2%) completed the trial (mean age, 48.8 years; 1381 [69.9%] women; 1778 [90.1%] underwent abdominal operations). In the intention-to-treat analysis, the primary outcome occurred in 211 of 989 patients (21.3%) in the high level of PEEP group compared with 233 of 987 patients (23.6%) in the low level of PEEP group (difference, -2.3% [95% CI, -5.9% to 1.4%]; risk ratio, 0.93 [95% CI, 0.83 to 1.04]; P = .23). Among the 9 prespecified secondary outcomes, 6 were not significantly different between the high and low level of PEEP groups, and 3 were significantly different, including fewer patients with hypoxemia (5.0% in the high level of PEEP group vs 13.6% in the low level of PEEP group; difference, -8.6% [95% CI, -11.1% to 6.1%]; P < .001). Conclusions and Relevance: Among obese patients undergoing surgery under general anesthesia, an intraoperative mechanical ventilation strategy with a higher level of PEEP and alveolar recruitment maneuvers, compared with a strategy with a lower level of PEEP, did not reduce postoperative pulmonary complications. Trial Registration: ClinicalTrials.gov Identifier: NCT02148692.