-
Anesthesiology Oct 2019Positive end-expiratory pressure (PEEP) increases lung volume and protects against alveolar collapse during anesthesia. During emergence, safety preoxygenation... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Positive end-expiratory pressure (PEEP) increases lung volume and protects against alveolar collapse during anesthesia. During emergence, safety preoxygenation preparatory to extubation makes the lung susceptible to gas absorption and alveolar collapse, especially in dependent regions being kept open by PEEP. We hypothesized that withdrawing PEEP before starting emergence preoxygenation would limit postoperative atelectasis formation.
METHODS
This was a randomized controlled evaluator-blinded trial in 30 healthy patients undergoing nonabdominal surgery under general anesthesia and mechanical ventilation with PEEP 7 or 9 cm H2O depending on body mass index. A computed tomography scan at the end of surgery assessed baseline atelectasis. The study subjects were thereafter allocated to either maintained PEEP (n = 16) or zero PEEP (n = 14) during emergence preoxygenation. The primary outcome was change in atelectasis area as evaluated by a second computed tomography scan 30 min after extubation. Oxygenation was assessed by arterial blood gases.
RESULTS
Baseline atelectasis was small and increased modestly during awakening, with no statistically significant difference between groups. With PEEP applied during awakening, the increase in atelectasis area was median (range) 1.6 (-1.1 to 12.3) cm and without PEEP 2.3 (-1.6 to 7.8) cm. The difference was 0.7 cm (95% CI, -0.8 to 2.9 cm; P = 0.400). Postoperative atelectasis for all patients was median 5.2 cm (95% CI, 4.3 to 5.7 cm), corresponding to median 2.5% of the total lung area (95% CI, 2.0 to 3.0%). Postoperative oxygenation was unchanged in both groups when compared to oxygenation in the preoperative awake state.
CONCLUSIONS
Withdrawing PEEP before emergence preoxygenation does not reduce atelectasis formation after nonabdominal surgery. Despite using 100% oxygen during awakening, postoperative atelectasis is small and does not affect oxygenation, possibly conditional on an open lung during anesthesia, as achieved by intraoperative PEEP.
Topics: Adult; Aged; Female; Humans; Male; Middle Aged; Positive-Pressure Respiration; Postoperative Complications; Pulmonary Atelectasis; Tomography, X-Ray Computed
PubMed: 31107276
DOI: 10.1097/ALN.0000000000002764 -
Annals of Palliative Medicine Oct 2021In clinical general thoracic surgery, the prevalence of atelectasis is relatively high. Perioperative interventions can affect the probability of patients with... (Meta-Analysis)
Meta-Analysis
BACKGROUND
In clinical general thoracic surgery, the prevalence of atelectasis is relatively high. Perioperative interventions can affect the probability of patients with atelectasis after surgery. Therefore, the incidence of perioperative intervention to prevent atelectasis after thoracic surgery was discussed using meta-analysis in this study.
METHODS
The articles were searched in the English database PubMed and Chinese databases including China National Knowledge Infrastructure (CNKI), VIP, and China Journal Full-text Database (CJFD). The duration for publication time of the articles was from the database inception to March 2021, and the articles were required to be randomized controlled trials (RCTs) using interventions [such as changing the dose of general anesthesia, continuous positive end expiratory pressure (PEEP), non-invasive pressure support ventilation, and physical therapy] after thoracic surgery (such as pulmonary lobectomy, sternum surgery, and lung cancer surgery) for the treatment of atelectasis. The software RevMan 5.3 provided by the Cochrane Collaboration was used for meta-analysis.
RESULTS
A total of 5 articles were obtained, including 375 cases in the control group and 268 cases in the intervention treatment group. A meta-analysis was performed on the included articles, combined effect model analysis results showed that compared with the control group, the use of PEEP during mechanical ventilation can significantly reduce the incidence of atelectasis [odds ratio (OR) =0.46; 95% confidence interval (CI): 0.31-0.67; Z=3.94; P<0.0001].
DISCUSSION
Perioperative intervention was more effective for postoperative atelectasis and other complications.
Topics: Humans; Positive-Pressure Respiration; Postoperative Complications; Pulmonary Atelectasis; Thoracic Surgery; Thoracic Surgical Procedures
PubMed: 34763434
DOI: 10.21037/apm-21-2441 -
Journal of Clinical Anesthesia May 2024Dexmedetomidine improves intrapulmonary shunt in thoracic surgery and minimizes inflammatory response during one-lung ventilation (OLV). However, it is unclear whether... (Meta-Analysis)
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/cmHO (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.
Topics: Humans; Dexmedetomidine; One-Lung Ventilation; Thoracic Surgery; Lung; Pulmonary Atelectasis; Pneumonia; Respiratory Distress Syndrome; Postoperative Complications; Hypoxia
PubMed: 37988813
DOI: 10.1016/j.jclinane.2023.111345 -
Respiratory Care Apr 2015The sigh is a normal homeostatic reflex that maintains lung compliance and decreases atelectasis. General anesthesia abolishes the sigh reflex with rapid onset of... (Review)
Review
BACKGROUND
The sigh is a normal homeostatic reflex that maintains lung compliance and decreases atelectasis. General anesthesia abolishes the sigh reflex with rapid onset of atelectasis in 100% of patients. Studies show a strong correlation between atelectasis and postoperative pulmonary complications, raising health-care costs. Alveolar recruitment maneuvers recruit collapsed alveoli, increase gas exchange, and improve arterial oxygenation. There is no consensus in the literature about the benefits of alveolar recruitment maneuvers. A systematic review is necessary to delineate their usefulness.
METHODS
The search strategy included utilizing PubMed, CINAHL, the Cochrane Library, the National Guideline Clearinghouse, and all subsequent research reference lists up to January 2014. Inclusion criteria involved studies that compared the use of an alveolar recruitment maneuver with a control group lacking an alveolar recruitment maneuver in adult surgical subjects not suffering from ARDS or undergoing cardiac or thoracic surgeries.
RESULTS
Six randomized controlled trials of the 439 studies initially identified achieved a score of ≥ 3 on the Jadad scale and were included in this review. Alveolar recruitment maneuvers consisted of a stepwise increase in tidal volume to a plateau pressure of 30 cm H2O, a stepwise increase in PEEP to 20 cm H2O, or sustained manual inflations of the anesthesia reservoir bag to a peak inspiratory pressure of 40 cm H2O. Subjects in the alveolar recruitment maneuver groups experienced a higher intraoperative PaO2 with improved lung compliance. Different alveolar recruitment maneuvers were equally effective. There was a significant advantage when alveolar recruitment maneuvers were followed by PEEP application.
CONCLUSIONS
Alveolar recruitment maneuvers followed by PEEP should be instituted after induction of general anesthesia, routinely during maintenance, and in the presence of a falling SpO2 whenever feasible. They allow the anesthesia provider to reduce the FIO2 while maintaining a higher SpO2 , limiting the masking of shunts. Utilization of alveolar recruitment maneuvers may reduce postoperative pulmonary complications and improve patient outcomes.
Topics: Adult; Aged; Anesthesia, General; Blood Gas Analysis; Female; Humans; Lung Compliance; Male; Middle Aged; Oxygen Consumption; Positive-Pressure Respiration; Pulmonary Alveoli; Pulmonary Atelectasis; Pulmonary Gas Exchange; Randomized Controlled Trials as Topic; Recruitment, Neurophysiological; Tidal Volume
PubMed: 25425708
DOI: 10.4187/respcare.03488 -
Anesthesiology Nov 2020Pulmonary atelectasis is frequent in clinical settings. Yet there is limited mechanistic understanding and substantial clinical and biologic controversy on its...
BACKGROUND
Pulmonary atelectasis is frequent in clinical settings. Yet there is limited mechanistic understanding and substantial clinical and biologic controversy on its consequences. The authors hypothesize that atelectasis produces local transcriptomic changes related to immunity and alveolar-capillary barrier function conducive to lung injury and further exacerbated by systemic inflammation.
METHODS
Female sheep underwent unilateral lung atelectasis using a left bronchial blocker and thoracotomy while the right lung was ventilated, with (n = 6) or without (n = 6) systemic lipopolysaccharide infusion. Computed tomography guided samples were harvested for NextGen RNA sequencing from atelectatic and aerated lung regions. The Wald test was used to detect differential gene expression as an absolute fold change greater than 1.5 and adjusted P value (Benjamini-Hochberg) less than 0.05. Functional analysis was performed by gene set enrichment analysis.
RESULTS
Lipopolysaccharide-unexposed atelectatic versus aerated regions presented 2,363 differentially expressed genes. Lipopolysaccharide exposure induced 3,767 differentially expressed genes in atelectatic lungs but only 1,197 genes in aerated lungs relative to the corresponding lipopolysaccharide-unexposed tissues. Gene set enrichment for immune response in atelectasis versus aerated tissues yielded negative normalized enrichment scores without lipopolysaccharide (less than -1.23, adjusted P value less than 0.05) but positive scores with lipopolysaccharide (greater than 1.33, adjusted P value less than 0.05). Leukocyte-related processes (e.g., leukocyte migration, activation, and mediated immunity) were enhanced in lipopolysaccharide-exposed atelectasis partly through interferon-stimulated genes. Furthermore, atelectasis was associated with negatively enriched gene sets involving alveolar-capillary barrier function irrespective of lipopolysaccharide (normalized enrichment scores less than -1.35, adjusted P value less than 0.05). Yes-associated protein signaling was dysregulated with lower nuclear distribution in atelectatic versus aerated lung (lipopolysaccharide-unexposed: 10.0 ± 4.2 versus 13.4 ± 4.2 arbitrary units, lipopolysaccharide-exposed: 8.1 ± 2.0 versus 11.3 ± 2.4 arbitrary units, effect of lung aeration, P = 0.003).
CONCLUSIONS
Atelectasis dysregulates the local pulmonary transcriptome with negatively enriched immune response and alveolar-capillary barrier function. Systemic lipopolysaccharide converts the transcriptomic immune response into positive enrichment but does not affect local barrier function transcriptomics. Interferon-stimulated genes and Yes-associated protein might be novel candidate targets for atelectasis-associated injury.
Topics: Animals; Female; Immunity, Cellular; Lung Volume Measurements; Pulmonary Atelectasis; Sheep; Transcriptome
PubMed: 32796202
DOI: 10.1097/ALN.0000000000003491 -
NMR in Biomedicine Dec 2014Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute... (Review)
Review
Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury, which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of computed tomography, positron emission tomography, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized (HP) gas MRI--a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces--is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of (3) He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces, (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces, and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation.
Topics: Animals; Diffusion Magnetic Resonance Imaging; Helium; Humans; Lung; Pulmonary Atelectasis; Respiration, Artificial; Respiratory Distress Syndrome
PubMed: 24920074
DOI: 10.1002/nbm.3136 -
Endokrynologia Polska 2022Not required for Clinical Vignette.
Not required for Clinical Vignette.
Topics: Goiter, Substernal; Humans; Lung; Pulmonary Atelectasis; Thyroidectomy
PubMed: 36059170
DOI: 10.5603/EP.a2022.0043 -
Respiratory Care Feb 2018The cough mechanism is often impaired in children with quadriplegic spastic cerebral palsy, accounting for the high prevalence of pneumonia and atelectasis requiring... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
The cough mechanism is often impaired in children with quadriplegic spastic cerebral palsy, accounting for the high prevalence of pneumonia and atelectasis requiring prolonged hospitalization. Conventional chest physiotherapy (CPT) is a current technique recommended at the onset of lower-respiratory infections in cerebral palsy. Previous studies have demonstrated the usefulness of mechanical insufflation-exsufflation (MI-E) in children with neuromuscular disease. To date, there has been no study of MI-E in children with quadriplegic spastic cerebral palsy. The objective of the study is to compare the efficacy in reducing hospital stay and improvement of atelectasis between MI-E and CPT in children with quadriplegic spastic cerebral palsy with lower-respiratory infections.
METHODS
This study is a randomized controlled trial. Children with quadriplegic spastic cerebral palsy, age 6 months to 18 y, admitted for lower-respiratory infections and/or atelectasis at King Chulalongkorn Memorial Hospital between June 1, 2014, and March 31, 2015, were recruited. Those with pneumothorax, severe pneumonia, active tuberculosis, and shock were excluded. Children were randomized into the MI-E or CPT group. The MI-E group received MI-E (3 therapies/d), and the CPT group received CPT (1 therapy/d). Vital signs per protocol and chest radiograph as needed were recorded.
RESULTS
There were 22 children enrolled in the study, 11 in the MI-E and 11 in the CPT group. Demographic data were comparable in both groups. The length of hospital stay was similar in both groups (MI-E 4-24 d vs CPT 6-42 d, = .15). There were 17 subjects with atelectasis (MI-E [ = 9] versus CPT [ = 8]). In this atelectasis subgroup, MI-E had shortened therapy time when compared with CPT (2.9 ± 0.8 d vs 3.9 ± 0.6 d, = .01). No complications were observed.
CONCLUSIONS
MI-E is proven to be beneficial in shortening the duration of airway clearance in children with quadriplegic spastic cerebral palsy presenting with lower-respiratory infections and atelectasis. MI-E is a safe and efficient intervention for airway clearance.
Topics: Adolescent; Cerebral Palsy; Child; Child, Preschool; Cough; Female; Humans; Infant; Insufflation; Length of Stay; Male; Mucociliary Clearance; Physical Therapy Modalities; Pulmonary Atelectasis; Respiratory Therapy; Respiratory Tract Infections; Treatment Outcome
PubMed: 29066586
DOI: 10.4187/respcare.05663 -
Anesthesiology Jul 2019During anesthesia oxygenation is impaired, especially in the elderly or obese, but the mechanisms are uncertain.
WHAT WE ALREADY KNOW ABOUT THIS TOPIC
During anesthesia oxygenation is impaired, especially in the elderly or obese, but the mechanisms are uncertain.
WHAT THIS ARTICLE TELLS US THAT IS NEW
Pooled data were examined from 80 patients studied with multiple inert gas elimination technique and computed tomography. Oxygenation was impaired by anesthesia, more so with greater age or body mass index. The key contributors were low ventilation/perfusion ratio (likely airway closure) in the elderly and shunt (atelectasis) in the obese.
BACKGROUND
Anesthesia is increasingly common in elderly and overweight patients and prompted the current study to explore mechanisms of age- and weight-dependent worsening of arterial oxygen tension (PaO2).
METHODS
This is a primary analysis of pooled data in patients with (1) American Society of Anesthesiologists (ASA) classification of 1; (2) normal forced vital capacity; (3) preoxygenation with an inspired oxygen fraction (FIO2) more than 0.8 and ventilated with FIO2 0.3 to 0.4; (4) measurements done during anesthesia before surgery. Eighty patients (21 women and 59 men, aged 19 to 69 yr, body mass index up to 30 kg/m2) were studied with multiple inert gas elimination technique to assess shunt and perfusion of poorly ventilated regions (low ventilation/perfusion ratio [(Equation is included in full-text article.)]) and computed tomography to assess atelectasis.
RESULTS
PaO2/FIO2 was lower during anesthesia than awake (368; 291 to 470 [median; quartiles] vs. 441; 397 to 462 mm Hg; P = 0.003) and fell with increasing age and body mass index. Log shunt was best related to a quadratic function of age with largest shunt at 45 yr (r2 =0.17, P = 0.001). Log shunt was linearly related to body mass index (r2 = 0.15, P < 0.001). A multiple regression analysis including age, age2, and body mass index strengthened the association further (r2 = 0.27). Shunt was highly associated to atelectasis (r2 = 0.58, P < 0.001). Log low (Equation is included in full-text article.)showed a linear relation to age (r2 = 0.14, P = 0.001).
CONCLUSIONS
PaO2/FIO2 ratio was impaired during anesthesia, and the impairment increased with age and body mass index. Shunt was related to atelectasis and was a more important cause of oxygenation impairment in middle-aged patients, whereas low(Equation is included in full-text article.), likely caused by airway closure, was more important in elderly patients. Shunt but not low(Equation is included in full-text article.)increased with increasing body mass index. Thus, increasing age and body mass index impaired gas exchange by different mechanisms during anesthesia.
Topics: Adult; Age Factors; Aged; Anesthesia; Body Mass Index; Body Weight; Female; Humans; Lung; Male; Middle Aged; Obesity; Oxygen; Pulmonary Atelectasis; Pulmonary Gas Exchange; Sweden; Tomography, X-Ray Computed; Ventilation-Perfusion Ratio; Young Adult
PubMed: 31045901
DOI: 10.1097/ALN.0000000000002693 -
Revista Brasileira de Terapia Intensiva 2019To determine the occurrence and characteristics of atelectasis, opacities, hypolucency and pulmonary infiltrates observed on chest X-rays of preterm infants in a... (Observational Study)
Observational Study
OBJECTIVE
To determine the occurrence and characteristics of atelectasis, opacities, hypolucency and pulmonary infiltrates observed on chest X-rays of preterm infants in a neonatal intensive care unit.
METHODS
This was a cross-sectional observational study. From August to December 2017, all chest radiographs of newborn infants were analyzed. The study included the chest radiographs of preterm neonates with gestational ages up to 36 weeks in the neonatal period that showed clear changes or suspected changes, which were confirmed after a radiologist's report. Radiological changes were associated with possible predisposing factors.
RESULTS
During the study period, 450 radiographs were performed on preterm neonates, and 37 lung changes were identified and classified into 4 types: 12 (2.66%) changes were described as opacities, 11 (2.44%) were described as atelectasis, 10 (2.22%) were described as pulmonary infiltrate, and 4 (0.88%) were described as hypolucency. A higher occurrence of atelectasis was noted in the right lung (81.8%). Among the abnormal radiographs, 25 (67.6%) newborn infants were receiving invasive mechanical ventilation.
CONCLUSION
Considering the radiological report, no significance was found for the observed changes. Atelectasis was not the most frequently observed change. The predisposing factors for these changes were extreme prematurity, low weight, male sex, a poorly positioned endotracheal tube and the use of invasive mechanical ventilation.
Topics: Cross-Sectional Studies; Female; Humans; Infant, Newborn; Infant, Premature; Lung; Male; Prospective Studies; Pulmonary Atelectasis; Radiography, Thoracic
PubMed: 31618354
DOI: 10.5935/0103-507X.20190047