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.

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.

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.

High prevalence of upper lung field pulmonary fibrosis radiologically consistent with pleuroparenchymal fibroelastosis in patients with round atelectasis.

BACKGROUND: Upper-lung field pulmonary fibrosis (upper-PF), radiologically consistent with pleuroparenchymal fibroelastosis (PPFE), was reported to develop in patients with a history of asbestos exposure and tuberculous pleurisy, indicating that chronic pleuritis is correlated with upper-PF development. Round atelectasis reportedly emerges after chronic pleuritis. This study aimed to clarify the association between round atelectasis and upper-PF. METHODS: We examined the radiological reports of all consecutive patients with round atelectasis between 2006 and 2018 and investigated the incidence of upper-PF development. RESULTS: Among 85 patients with round atelectasis, 21 patients (24.7%) were confirmed to finally develop upper-PF lesions. Upper-PF was diagnosed after round atelectasis recognition in more than half of the patients (13/21, 61.9%), whereas upper-PF and round atelectasis were simultaneously detected in the remaining 8 patients. At the time of round atelectasis detection, almost all patients (19/21, 90.5%) had diffuse pleural thickening and round atelectasis was commonly observed in non-upper lobes of 19 patients (90.5%). Fourteen patients had round atelectasis in unilateral lung, and the remaining 7 patients had round atelectasis in bilateral lungs. Among all 14 patients with unilateral round atelectasis, upper-PF developed on the same (n = 11) or both sides (n = 3). Thus, upper-PF emerged on the same side where round atelectasis was present (14/14, 100%). The autopsy of one patient revealed a thickened parietal-visceral pleura suggestive of chronic pleuritis. Subpleural fibroelastosis was also observed. CONCLUSIONS: Upper-PF occasionally develops on the same side of round atelectasis. Upper-PF may develop as a sequela of chronic pleuritis.

Effects of an open lung extubation strategy compared with a conventional extubation strategy on postoperative pulmonary complications after general anesthesia: a single-centre pilot randomized controlled trial.

PURPOSE: Postoperative pulmonary complications (PPCs) are a common cause of morbidity. Postoperative atelectasis is thought to be a significant risk factor in their development. Recent imaging studies suggest that patients' extubation may result in similar postoperative atelectasis regardless of the intraoperative mechanical ventilation strategy used. In this pilot trial, we hypothesized that a study investigating the effects of an open lung extubation strategy compared with a conventional one on PPCs would be feasible. METHODS: We conducted a pilot, single-centre, double-blinded randomized controlled trial. Adult patients at moderate to high risk of PPCs and scheduled for elective surgery were eligible. Patients were randomized to an open lung extubation strategy (semirecumbent position, fraction of inspired oxygen [FIO2] 50%, pressure support ventilation, unchanged positive end-expiratory pressure) or to a conventional extubation strategy (dorsal decubitus position, FIO2 100%, manual bag ventilation). The primary feasibility outcome was global protocol adherence while the primary exploratory efficacy outcome was PPCs. RESULTS: We randomized 35 patients to the conventional extubation group and 34 to the open lung extubation group. We observed a global protocol adherence of 96% (95% confidence interval, 88 to 99), which was not different between groups. Eight PPCs occurred (two in the conventional extubation group vs six in the open lung extubation group). Less postoperative supplemental oxygen and better lung aeration were observed in the open lung extubation group. CONCLUSIONS: In this single-centre pilot trial, we observed excellent feasibility. A multicentre pilot trial comparing the effect of an open lung extubation strategy with that of a conventional extubation strategy on the occurrence of PPCs is feasible. STUDY REGISTRATION DATE: ClinicalTrials.gov (NCT04993001); registered 6 August 2021.

RéSUMé: OBJECTIF: Les complications pulmonaires postopératoires (CPP) sont une cause fréquente de morbidité. L'atélectasie postopératoire est considérée comme un facteur de risque important de CPP. Des études d'imagerie récentes suggèrent que l'extubation des patient·es peut entraîner une atélectasie postopératoire semblable, quelle que soit la stratégie de ventilation mécanique peropératoire utilisée. Dans cet essai pilote, nous avons émis l'hypothèse qu'une étude examinant les effets sur les CPP d'une stratégie d'extubation à poumon ouvert par rapport à une stratégie d'extubation conventionnelle serait réalisable. MéTHODE: Nous avons mené une étude randomisée contrôlée pilote, monocentrique et à double insu. Les patient·es adultes présentant un risque modéré à élevé de CPP et devant bénéficier d'une chirurgie non urgente étaient éligibles. Les patient·es ont été randomisé·es à une prise en charge par une stratégie d'extubation à poumon ouvert (position semi-couchée, fraction d'oxygène inspiré [FIO2] 50 %, ventilation par aide inspiratoire, pression positive télé-expiratoire inchangée) ou à une stratégie d'extubation conventionnelle (décubitus dorsal, FIO2 100 %, ventilation manuelle par masque). Le principal critère de faisabilité était l'adhésion au protocole global, tandis que les CPP constituaient le principal critère d'efficacité exploratoire. RéSULTATS: Nous avons randomisé 35 patient·es dans le groupe d'extubation conventionnelle et 34 dans le groupe d'extubation à poumon ouvert. Nous avons observé une adhésion globale au protocole de 96 % (intervalle de confiance à 95 %, 88 à 99), qui n'était pas différente entre les groupes. Huit CPP sont survenues (deux dans le groupe d'extubation conventionnelle vs six dans le groupe d'extubation à poumon ouvert). Nous avons observé des besoins moins importants en oxygène supplémentaire postopératoire et une meilleure aération pulmonaire dans le groupe extubé à poumon ouvert. CONCLUSION: Dans cet essai pilote monocentrique, nous avons observé une excellente faisabilité. Une étude pilote multicentrique comparant l'effet d'une stratégie d'extubation à poumon ouvert à celui d'une stratégie d'extubation conventionnelle sur la survenue de CPP est réalisable. DATE D'ENREGISTREMENT DE L'éTUDE: ClinicalTrials.gov (NCT04993001); enregistrée le 6 août 2021.

The effect of driving pressure-guided versus conventional mechanical ventilation strategy on pulmonary complications following on-pump cardiac surgery: A randomized clinical trial.

STUDY OBJECTIVE: Postoperative pulmonary complications occur frequently and are associated with worse postoperative outcomes in cardiac surgical patients. The advantage of driving pressure-guided ventilation strategy in decreasing pulmonary complications remains to be definitively established. We aimed to investigate the effect of intraoperative driving pressure-guided ventilation strategy compared with conventional lung-protective ventilation on pulmonary complications following on-pump cardiac surgery. DESIGN: Prospective, two-arm, randomized controlled trial. SETTING: The West China university hospital in Sichuan, China. PATIENTS: Adult patients who were scheduled for elective on-pump cardiac surgery were enrolled in the study. INTERVENTIONS: Patients undergoing on-pump cardiac surgery were randomized to receive driving pressure-guided ventilation strategy based on positive end-expiratory pressure (PEEP) titration or conventional lung-protective ventilation strategy with fixed 5 cmH2O of PEEP. MEASUREMENTS: The primary outcome of pulmonary complications (including acute respiratory distress syndrome, atelectasis, pneumonia, pleural effusion, and pneumothorax) within the first 7 postoperative days were prospectively identified. Secondary outcomes included pulmonary complication severity, ICU length of stay, and in-hospital and 30-day mortality. MAIN RESULTS: Between August 2020 and July 2021, we enrolled 694 eligible patients who were included in the final analysis. Postoperative pulmonary complications occurred in 140 (40.3%) patients in the driving pressure group and 142 (40.9%) in the conventional group (relative risk, 0.99; 95% confidence interval, 0.82-1.18; P = 0.877). Intention-to-treat analysis showed no significant difference between study groups regarding the incidence of primary outcome. The driving pressure group had less atelectasis than the conventional group (11.5% vs 17.0%; relative risk, 0.68; 95% confidence interval, 0.47-0.98; P = 0.039). Secondary outcomes did not differ between groups. CONCLUSION: Among patients who underwent on-pump cardiac surgery, the use of driving pressure-guided ventilation strategy did not reduce the risk of postoperative pulmonary complications when compared with conventional lung-protective ventilation strategy.

Postoperative pulmonary complications after sugammadex reversal of neuromuscular blockade: a systematic review and meta-analysis with trial sequential analysis.

BACKGROUND: Sugammadex has been reported to lower the incidence of postoperative residual neuromuscular blockade. Despite the advantages, until recently the effects of sugammadex on postoperative pulmonary complications (PPCs) were controversial. We conducted a systematic review and meta-analysis to determine whether reversal with sugammadex was associated with a lower risk of PPCs compared with neostigmine. METHODS: PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched from inception to May 2022. Randomized controlled trials (RCTs) and observational studies comparing PPCs in patients receiving sugammadex or neostigmine as reversal agent at the end of surgery were included. The primary outcomes focused on PPCs including desaturation, pneumonia, atelectasis, noninvasive ventilation (NIV) and reintubation. Trial sequential analysis was performed on the primary outcomes to confirm whether firm evidence was reached. RESULTS: Meta-analysis of included studies showed that the rate of desaturation (43.2% vs 45.0%, RR = 0.82; 95% CI 0.63 to 1.05; p = 0.11) were comparable between the two groups. When looking at other primary outcomes, significantly lower risk of pneumonia (1.37% vs 2.45%, RR = 0.65; 95% CI 0.49 to 0.85; p = 0.002), atelectasis (24.6% vs 30.4%, RR = 0.64; 95% CI 0.42 to 0.98; p = 0.04), NIV (1.37% vs 2.33%, RR = 0.65; 95% CI 0.43 to 0.98; p = 0.04) and reintubation (0.99% vs 1.65%, RR = 0.62; 95% CI 0.43 to 0.91; p = 0.01) in the sugammadex group were detected compared with the neostigmine group. CONCLUSIONS: We concluded that sugammadex is more effective at reducing the incidence of PPCs including pneumonia, atelectasis, NIV and reintubation compared with neostigmine. Further evidence, preferably from RCTs, is required to confirm these findings.

Efficacy of prophylactic high-flow nasal cannula therapy for postoperative pulmonary complications after pediatric cardiac surgery: a prospective single-arm study.

PURPOSE: This study investigated the incidence of postoperative pulmonary complications (PPC) when high-flow nasal cannula therapy (HFNC) is used prophylactically after pediatric cardiac surgery, and evaluated its efficacy. METHODS: This was a single-arm prospective interventional study that was conducted in a tertiary teaching hospital with eight beds in the pediatric cardiac ICU after approval by the Ethics Committee. One-hundred children under the age of 48 months who were scheduled for cardiac surgery for congenital heart disease were recruited. HFNC was used for 24 h after extubation at a 2 L/kg/min flow rate. The primary outcome was the incidence of PPC within 48 h after extubation. PPC was defined as atelectasis and acute respiratory failure meeting certain criteria. We considered prophylactic HFNC as effective if the prevalence of PPC was < 10%, based on previous reports of reintubation rates of 6%-9% after pediatric cardiac surgery. RESULTS: A total of 91 patients were finally included in the analysis. The incidence of PPC within 48 h after extubation was 18.7%, whereas atelectasis was observed in 13.2%, and acute respiratory failure in 8.8%. Reintubation rate within 48 h after extubation was 0%. CONCLUSIONS: We found the incidence of PPC with prophylactic HFNC after planned extubation after pediatric cardiac surgery. However, the incidence was > 10%; therefore, we could not demonstrate its efficacy in this single-arm study. Further studies are needed to investigate whether the HFNC could be adapted as first-line oxygen therapy after pediatric cardiac surgery.

Model for predicting early and late-onset postoperative pulmonary complications in perioperative patients receiving neuromuscular blockade: a secondary analysis.

Pulmonary complications continue to be the most common adverse event after surgery. The main objective was to carry out two independent predictive models, both for early pulmonary complications in the Post-Anesthesia Care Unit and late-onset pulmonary complications after 30 postoperative days. The secondary objective was to determine whether presenting early complications subsequently causes patients to have other late-onset events. This is a secondary analysis of a cohort study. 714 patients were divided into four groups depending on the neuromuscular blocking agent, and spontaneous or pharmacological reversal. Incidence of late-onset complications if we have not previously had any early complications was 4.96%. If the patient has previously had early complications the incidence of late-onset complications was 22.02%. If airway obstruction occurs, the risk of atelectasis increased from 6.88 to 22.58% (p = 0.002). If hypoxemia occurs, the incidence increased from 5.82 to 21.79% (p < 0.001). Based on our predictive models, we conclude that diabetes mellitus and preoperative anemia are two risk factors for early and late-onset postoperative pulmonary complications, respectively. Hypoxemia and airway obstruction in Post-Anesthesia Care Unit increased four times the risk of the development of pneumonia and atelectasis at 30 postoperative days.

Is atelectasis related to the development of postoperative pneumonia? a retrospective single center study.

BACKGROUND: Atelectasis may play a substantial role in the development of pneumonia. However, pneumonia has never been evaluated as an outcome of atelectasis in surgical patients. We aimed to determine whether atelectasis is related to an increased risk of postoperative pneumonia, intensive care unit (ICU) admission and hospital length of stay (LOS). METHODS: The electronic medical records of adult patients who underwent elective non-cardiothoracic surgery under general anesthesia between October 2019 and August 2020 were reviewed. They were divided into two groups: one who developed postoperative atelectasis (atelectasis group) and the other who did not (non-atelectasis group). The primary outcome was the incidence of pneumonia within 30 days after the surgery. The secondary outcomes were ICU admission rate and postoperative LOS. RESULTS: Patients in the atelectasis group were more likely to have risk factors for postoperative pneumonia including age, body mass index, a history of hypertension or diabetes mellitus and duration of surgery, compared with those in the non-atelectasis. Among 1,941 patients, 63 (3.2%) developed postoperative pneumonia; 5.1% in the atelectasis group and 2.8% in the non-atelectasis (P = 0.025). In multivariable analysis, atelectasis was associated with an increased risk of pneumonia (adjusted odds ratio, 2.33; 95% CI: 1.24 - 4.38; P = 0.008). Median postoperative LOS was significantly longer in the atelectasis group (7 [interquartile range: 5-10 days]) than in the non-atelectasis (6 [3-8] days) (P < 0.001). Adjusted median duration was also 2.19 days longer in the atelectasis group (ß, 2.19; 95% CI: 0.821 - 2.834; P < 0.001). ICU admission rate was higher in the atelectasis group (12.1% vs. 6.5%; P < 0.001), but it did not differ between the groups after adjustment for confounders (adjusted odds ratio, 1.52; 95% CI: 0.88 - 2.62; P = 0.134). CONCLUSION: Among patients undergoing elective non-cardiothoracic surgery, patients with postoperative atelectasis were associated with a 2.33-fold higher incidence of pneumonia and a longer LOS than those without atelectasis. This finding alerts the need for careful management of perioperative atelectasis to prevent or reduce the adverse events including pneumonia and the burden of hospitalizations. TRIAL REGISTRATION: None.

Postoperative Pulmonary Complications in the ENIGMA II Trial: A Post Hoc Analysis.

BACKGROUND: Nitrous oxide promotes absorption atelectasis in poorly ventilated lung segments at high inspired concentrations. The Evaluation of Nitrous oxide In the Gas Mixture for Anesthesia (ENIGMA) trial found a higher incidence of postoperative pulmonary complications and wound sepsis with nitrous oxide anesthesia in major surgery compared to a fraction of inspired oxygen of 0.8 without nitrous oxide. The larger ENIGMA II trial randomized patients to nitrous oxide or air at a fraction of inspired oxygen of 0.3 but found no effect on wound infection or sepsis. However, postoperative pulmonary complications were not measured. In the current study, post hoc data were collected to determine whether atelectasis and pneumonia incidences were higher with nitrous oxide in patients who were recruited to the Australian cohort of ENIGMA II. METHODS: Digital health records of patients who participated in the trial at 10 Australian hospitals were examined blinded to trial treatment allocation. The primary endpoint was the incidence of atelectasis, defined as lung atelectasis or collapse reported on chest radiology. Pneumonia, as a secondary endpoint, required a diagnostic chest radiology report with fever, leukocytosis, or positive sputum culture. Comparison of the nitrous oxide and nitrous oxide-free groups was done according to intention to treat using chi-square tests. RESULTS: Data from 2,328 randomized patients were included in the final data set. The two treatment groups were similar in surgical type and duration, risk factors, and perioperative management recorded for ENIGMA II. There was a 19.3% lower incidence of atelectasis with nitrous oxide (171 of 1,169 [14.6%] vs. 210 of 1,159 [18.1%]; odds ratio, 0.77; 95% CI, 0.62 to 0.97; P = 0.023). There was no difference in pneumonia incidence (60 of 1,169 [5.1%] vs. 52 of 1159 [4.5%]; odds ratio, 1.15; 95% CI, 0.77 to 1.72; P = 0.467) or combined pulmonary complications (odds ratio, 0.84; 95% CI, 0.69 to 1.03; P = 0.093). CONCLUSIONS: In contrast to the earlier ENIGMA trial, nitrous oxide anesthesia in the ENIGMA II trial was associated with a lower incidence of lung atelectasis, but not pneumonia, after major surgery.

The effect of ultrasound-guided lung recruitment maneuvers on atelectasis in lung-healthy patients undergoing laparoscopic gynecologic surgery: a randomized controlled trial.

BACKGROUND: Atelectasis is the primary cause of hypoxemia during general anesthesia. This study aimed to evaluate the impact of the combination of recruitment maneuvers (RM) and positive end-expiratory pressure (PEEP) on the incidence of atelectasis in adult women undergoing gynecologic laparoscopic surgery using pulmonary ultrasound. METHODS: In this study, 42 patients with healthy lungs undergoing laparoscopic gynecologic surgery were randomly divided into the recruitment maneuver group (RM group; 6 cm H2O PEEP and RM) or the control group (C group; 6 cm H2O PEEP and no RM), 21 patients in each group. Volume-controlled ventilation was used in all selected patients, with a tidal volume of 6-8 mL·kg-1 of ideal body weight. When atelectasis was detected, patients in the RM group received ultrasound-guided RM, while those in the C group received no intervention. The incidence and severity of atelectasis were determined using lung ultrasound scores. RESULTS: A total of 41 patients were investigated. The incidence of atelectasis was lower in the RM group (40%) than in the C group (80%) 15 min after arrival in the post-anesthesia care unit (PACU). Meanwhile, lung ultrasound scores (LUSs) were lower in the RM group compared to the C group. In addition, the differences in the LUS between the two groups were mainly due to the differences in lung ultrasound scores in the posterior regions. However, this difference did not persist after 24 h of surgery. CONCLUSIONS: In conclusion, the combination of RM and PEEP could reduce the incidence of atelectasis in patients with healthy lungs 15 min after arrival at the PACU; however, it disappeared within 24 h after surgery. TRIAL REGISTRATION: (Prospectively registered): ChiCTR2000033529 . Registered on 4/6/2020.

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.

Is respiratory syncytial virus infection more dangerous than COVID 19 in the neonatal period?

OBJECTIVE: We aimed to compare the clinical features, laboratory findings and primary outcomes of the neonates with RSV and neonates with SARS-CoV-2 infections. MATERIALS AND METHODS: This nested case-control study included the neonates who were administered in the neonatal intensive care unit (NICU) of the University of Health Sciences, Dr Behçet Uz Children's Hospital during the period of 01 March-30 April 2020. Respiratory PCR samples and COVID-19 samples were taken simultaneously. Only RSV positive and COVID-19 positive infants were compared. Demographic, epidemiological and clinical data were obtained from hospital electronic information system medical records. The chest radiographs at the admission were evaluated by using standard definitions for normal chest X-ray, atelectasis, bronchopenumonia, peribronchial thickening and hyperinflation in various lung volumes. RESULTS: A total of 30 infants were enrolled in the study and RSV was identified in 20/30 infants (66%). No significant differences were observed between the two groups in terms of general characteristics. Comparing to the infants with Covid-19 infections, infants with RSV infections had significantly higher rates of having oxygen support (p = .03). Total NICU duration time was 6.7 ± 1.6 days in COVID positive group and 11.1 ± 5.1 days in the RSV group (p = .01). Infants with COVID-19 had more normal chest X-rays. Infants with RSV-positive had a significantly higher proportion of atelectasis than those with COVID-19 infants (p = .04). DISCUSSION: This is the first study that compares RSV infection and COVID-19 infection. RSV infection can be more serious in the neonatal period. In cases with suspected COVID-19 infection, it should be kept in mind if atelectasis is seen on chest radiography. Respiratory failure may be more serious in RSV positive infants and RSV infection may be more dangerous for the neonatal period.

Effects of high versus low inspiratory oxygen fraction on postoperative clinical outcomes in patients undergoing surgery under general anesthesia: A systematic review and meta-analysis of randomized controlled trials.

OBJECTIVES: To determine whether high perioperative inspired oxygen fraction (FiO2) compared with low FiO2 has more deleterious postoperative clinical outcomes in patients undergoing non-thoracic surgery under general anesthesia. DESIGN: Meta-analysis of randomized controlled trials. SETTING: Operating room, postoperative recovery room and surgical ward. PATIENTS: Surgical patients under general anesthesia. INTERVENTION: High perioperative FiO2 (≥0.8) vs. low FiO2 (≤0.5). MEASUREMENTS: The primary outcome was mortality within 30 days. Secondary outcomes were pulmonary outcomes (atelectasis, pneumonia, respiratory failure, postoperative pulmonary complications [PPCs], and postoperative oxygen parameters), intensive care unit (ICU) admissions, and length of hospital stay. A subgroup analysis was performed to explore the treatment effect by body mass index (BMI). MAIN RESULTS: Twenty-six trials with a total 4991 patients were studied. The mortality in the high FiO2 group did not differ from that in the low FiO2 group (risk ratio [RR] 0.91, 95% confidence interval [CI] 0.42-1.97, P = 0.810). Nor were there any significant differences between the groups in such outcomes as pneumonia (RR 1.19, 95% CI 0.74-1.92, P = 0.470), respiratory failure (RR 1.29, 95% CI 0.82-2.04, P = 0.270), PPCs (RR 1.05, 95% CI 0.69-1.59, P = 0.830), ICU admission (RR 0.94, 95% CI 0.55-1.60, P = 0.810), and length of hospital stay (mean difference [MD] 0.27 d, 95% CI -0.28-0.81, P = 0.340). The high FiO2 was associated with postoperative atelectasis more often (risk ratio 1.27, 95% CI 1.00-1.62, P = 0.050), and lower postoperative arterial partial oxygen pressure (MD -5.03 mmHg, 95% CI -7.90- -2.16, P < 0.001). In subgroup analysis of BMI >30 kg/m2, these parameters were similarly affected between the groups. CONCLUSIONS: The use of high FiO2 compared to low FiO2 did not affect the short-term mortality, although it may increase the incidence of atelectasis in adult, non-thoracic patients undergoing surgical procedures. Nor were there any significant differences in other secondary outcomes.

Preoperative incentive spirometry for preventing postoperative pulmonary complications in patients undergoing coronary artery bypass graft surgery: a prospective, randomized controlled trial.

BACKGROUND: Postoperative pulmonary complications (PPCs) often occur after cardiac operations and are a leading cause of morbidity, inhibit oxygenation, and increase hospital length of stay and mortality. Although clinical evidence for PPCs prevention is often unclear and crucial, measures occur to reduce PPCs. One device usually used for this reason is incentive spirometry (IS). The aim of the study is to evaluate the effect of preoperative incentive spirometry to prevent postoperative pulmonary complications, improve postoperative oxygenation, and decrease hospital stay following coronary artery bypass graft (CABG) surgery patients. METHODS: This was a clinical randomized prospective study. A total of 80 patients were selected as candidates for CABG at An-Najah National University Hospital, Nablus-Palestine. Patients had been randomly assigned into two groups: incentive spirometry group (IS), SI performed before surgery (study group) and control group, preoperative spirometry was not performed. The 40 patients in each group received the same protocol of anesthesia and ventilation in the operating room. RESULT: The study findings showed a significant difference between the IS and control groups in the incidence of postoperative atelectasis. There were 8 patients (20.0%) in IS group and 17 patients (42.5%) in the control group (p = 0.03). Mechanical ventilation duration was significantly less in IS group. The median was four hours versus six hours in the control group (p < 0.001). Hospital length of stay was significantly less in IS group, and the median was six days versus seven days in the control group (p < 0.001). The median of the amount of arterial blood oxygen and oxygen saturation was significantly improved in the IS group (p < 0.005). CONCLUSION: Preoperative incentive spirometry for two days along with the exercise of deep breathing, encouraged coughing, and early ambulation following CABG are in connection with prevention and decreased incidence of atelectasis, hospital stay, mechanical ventilation duration and improved postoperative oxygenation with better pain control. A difference that can be considered both significant and clinically relevant. Trial registration Thai Clinical Trials Registry: TCTR20201020005. Registered 17 October 2020-retrospectively registered.

Prevalence and clinical consequences of atelectasis in SARS-CoV-2 pneumonia: a computed tomography retrospective cohort study.

BACKGROUND: The aim of the study is to estimate the prevalence of atelectasis assessed with computer tomography (CT) in SARS-CoV-2 pneumonia and the relationship between the amount of atelectasis with oxygenation impairment, Intensive Care Unit admission rate and the length of in-hospital stay. PATIENTS AND METHODS: Two-hundred thirty-seven patients admitted to the hospital with SARS-CoV-2 pneumonia diagnosed by clinical, radiology and molecular tests in the nasopharyngeal swab who underwent a chest computed tomography because of a respiratory worsening from Apr 1 to Apr 30, 2020 were included in the study. Patients were divided into three groups depending on the presence and amount of atelectasis at the computed tomography: no atelectasis, small atelectasis (< 5% of the estimated lung volume) or large atelectasis (> 5% of the estimated lung volume). In all patients, clinical severity, oxygen-therapy need, Intensive Care Unit admission rate, the length of in-hospital stay and in-hospital mortality data were collected. RESULTS: Thirty patients (19%) showed small atelectasis while eight patients (5%) showed large atelectasis. One hundred and seventeen patients (76%) did not show atelectasis. Patients with large atelectasis compared to patients with small atelectasis had lower SatO2/FiO2 (182 vs 411 respectively, p = 0.01), needed more days of oxygen therapy (20 vs 5 days respectively, p = 0,02), more frequently Intensive Care Unit admission (75% vs 7% respectively, p < 0.01) and a longer period of hospitalization (40 vs 14 days respectively p < 0.01). CONCLUSION: In patients with SARS-CoV-2 pneumonia, atelectasis might appear in up to 24% of patients and the presence of larger amount of atelectasis is associated with worse oxygenation and clinical outcome.

Perioperative high inspired oxygen fraction induces atelectasis in patients undergoing abdominal surgery: A randomized controlled trial.

STUDY OBJECTIVE: We evaluated the feasibility of use and effects on postoperative atelectasis and complications of lower inspired oxygen fraction (FIO2) compared to conventional oxygen therapy. DESIGN: Single center, randomized clinical trial. SETTING: University hospital, operating room and postoperative recovery area. PATIENTS: One hundred ninety patients aged ≥50 with an American Society of Anesthesiologists physical status of I-III who underwent abdominal surgery with general anesthesia. INTERVENTIONS: Participants were randomly assigned to either the low FIO2 group (intraoperative: FIO2 0.35, during induction and recovery: FIO2 0.7) or the conventional FIO2 group (intraoperative: FIO2 0.6, during induction and recovery: FIO2 1.0). MEASUREMENTS: The primary outcome was postoperative atelectasis measured with lung ultrasonography at postoperative 30 min in the post-anesthesia care unit (consolidation score: each region 0-3, 12 region, total score range of 0 to 36, a lower score indicating better aeration). MAIN RESULTS: Seven patients in the low FIO2 group were omitted from the study due to changing FIO2 during intervention (7/95 (8.4%) vs. 2/95 (2.1%), p = 0.088; low FIO2 group vs. conventional FIO2 group). Overall, atelectasis was detected in 29.7% (51/172) of patients 30 min after surgery by lung ultrasound and 40.1% (69/172) of patients after 2 days after surgery by chest X-ray. The scores of lung ultrasonography and the incidence of significant atelectasis (consolidation score ≥ 2 at any region) were lower in the low FIO2 group than in the conventional FIO2 group (median [IQR]: 3 [1,6] vs. 7 [3,9], p < 0.001 and 17/85 (20%) vs. 34/87 (39%), RR: 0.512 [95% CI: 0.311-0.843], p = 0.006, respectively). The incidence of surgical site infection and length of hospitalization were not significantly different between the two groups. CONCLUSIONS: Based on our findings, decreased inspired oxygen fraction during anesthesia and recovery did not cause hypoxic events, but instead reduced immediate postoperative atelectasis. The use of intraoperative conventional higher inspired oxygen did not afford any clinical advantages for postoperative recovery in abdominal surgery.

Comparison of the efficacy and safety of cuffed versus uncuffed endotracheal tubes for infants in the intensive care setting: a pilot, unblinded RCT.

OBJECTIVE: To study effectiveness and safety of cuffed versus uncuffed endotracheal tubes (ETTs) in small infants in the intensive care unit (ICU). DESIGN: Pilot RCT. SETTING: Neonatal and paediatric ICUs of children's hospital in Western Australia. PARTICIPANTS: Seventy-six infants ≥35 weeks gestation and infants <3 months of age, ≥3 kg. INTERVENTIONS: Patients randomly assigned to Microcuff cuffed or Portex uncuffed ETT. MAIN OUTCOMES MEASURES: Primary outcome was achievement of optimal ETT leak in target range (10%-20%). Secondary outcomes included: reintubations, ventilatory parameters, ventilatory complications, postextubation complications and long-term follow-up. RESULTS: Success rate (achievement of mean leak in the range 10%-20%) was 13/42 (30.9%) in the cuffed ETT group and 6/34 (17.6%) in uncuffed ETT group (OR=2.09; 95% CI (0.71 to 6.08); p=0.28). Mean percentage time within target leak range in cuffed ETT group 28% (IQR: 9-42) versus 15% (IQR: 0-28) in uncuffed ETT group (p=0.01). There were less reintubations to optimise size in cuffed ETT group 0/40 versus 10/36 (p<0.001). No differences were found in gaseous exchange, ventilator parameters or postextubation complications. There were fewer episodes of atelectasis in cuffed ETT group 0/42 versus 4/34 (p=0.03). No patient had been diagnosed with subglottic stenosis at long-term follow-up. CONCLUSIONS: There was no difference in the primary outcome, though percentage time spent in optimal leak range was significantly higher in cuffed ETT group. Cuffed ETTs reduced reintubations to optimise ETT size and episodes of atelectasis. Cuffed ETTs may be a feasible alternative to uncuffed ETTs in this group of patients. TRIAL REGISTRATION NUMBER: ACTRN12615000081516.

Lung-protective mechanical ventilation for patients undergoing abdominal laparoscopic surgeries: a randomized controlled trial.

BACKGROUND: Pneumoperitoneum and Trendelenburg position in laparoscopic surgeries could contribute to postoperative pulmonary dysfunction. In recent years, intraoperative lung-protective mechanical ventilation (LPV) has been reportedly able to attenuate ventilator-induced lung injuries (VILI). Our objectives were to test the hypothesis that LPV could improve intraoperative oxygenation function, pulmonary mechanics and early postoperative atelectasis in laparoscopic surgeries. METHODS: In this randomized controlled clinical trial, 62 patients indicated for elective abdominal laparoscopic surgeries with an expected duration of greater than 2 h were randomly assigned to receive either lung-protective ventilation (LPV) with a tidal volume (Vt) of 7 ml kg- 1 ideal body weight (IBW), 10 cmH2O positive end-expiratory pressure (PEEP) combined with regular recruitment maneuvers (RMs) or conventional ventilation (CV) with a Vt of 10 ml kg- 1 IBW, 0 cmH2O in PEEP and no RMs. The primary endpoints were the changes in the ratio of PaO2 to FiO2 (P/F). The secondary endpoints were the differences between the two groups in PaO2, alveolar-arterial oxygen gradient (A-aO2), intraoperative pulmonary mechanics and the incidence of atelectasis detected on chest x-ray on the first postoperative day. RESULTS: In comparison to CV group, the intraoperative P/F and PaO2 in LPV group were significantly higher while the intraoperative A-aO2 was clearly lower. Cdyn and Cstat at all the intraoperative time points in LPV group were significantly higher compared to CV group (p < 0.05). There were no differences in the incidence of atelectasis on day one after surgery between the two groups. CONCLUSIONS: Lung protective mechanical ventilation significantly improved intraoperative pulmonary oxygenation function and pulmonary compliance in patients experiencing various abdominal laparoscopic surgeries, but it could not ameliorate early postoperative atelectasis and oxygenation function on the first day after surgery. TRIAL REGISTRATION: https://www.clinicaltrials.gov/identifier: NCT04546932 (09/05/2020).