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Anesthesiology Jan 2022Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface... (Review)
Review
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.
Topics: Animals; Diaphragm; Humans; Intraoperative Complications; Lung; Perioperative Care; Pulmonary Atelectasis; Respiration, Artificial
PubMed: 34499087
DOI: 10.1097/ALN.0000000000003943 -
Anesthesiology Jan 2022The development of pulmonary atelectasis is common in the surgical patient. Pulmonary atelectasis can cause various degrees of gas exchange and respiratory mechanics... (Review)
Review
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.
Topics: Humans; Intraoperative Complications; Lung; Manometry; Obesity; Perioperative Care; Positive-Pressure Respiration; Pulmonary Atelectasis; Respiration, Artificial; Risk Factors; Smoking
PubMed: 34710217
DOI: 10.1097/ALN.0000000000004009 -
RoFo : Fortschritte Auf Dem Gebiete Der... Oct 2019High diagnostic accuracy, increasing clinical experience and technical improvements are good reasons to consider lung ultrasound (US) for the assessment of pleural... (Review)
Review
BACKGROUND
High diagnostic accuracy, increasing clinical experience and technical improvements are good reasons to consider lung ultrasound (US) for the assessment of pleural and pulmonary diseases. In the emergency room and in intensive care, it is well acknowledged, but application in other settings is rare. The aim of this review is to update potential users in general radiology about the diagnostic scope of lung US and to encourage more frequent use of this generally underestimated lung imaging modality.
METHOD
Literature review was done independently by the two authors in MEDLINE (via PubMed) covering a time span from 2002 until 2017 using free text and Medical Subject Headings/MeSH. Article selection for the bibliography was based on consensus according to relevance and evidence.
RESULTS AND CONCLUSION
The technical prerequisites include a standard ultrasound unit with a suitable transducer. Pleural effusion and pneumothorax, atelectasis, interstitial edema, pneumonia, exacerbated chronic obstructive pulmonary disease/asthma and pulmonary embolism can be distinguished by particular ultrasound signs, artifacts and their combinations. A highly standardized selection of access points and terminology for the description of imaging findings contributes to high diagnostic accuracy even in challenging patients and settings. Besides the assessment of acute respiratory failure in the emergency room, lung US may be used for monitoring interstitial fluid accumulation in volume therapy and for the diagnosis of pneumonia or the assessment of pleural effusion and pleurisy in a routine outpatient setting. Last but not least, the increasing concerns about medical radiation exposure warrant a more extensive use of this sometimes underestimated modality as a cost-, time- and radiation-saving alternative or valuable adjunct to the standard imaging modalities.
KEY POINTS
· Lung US is a safe, quick and readily available method with options for dynamic imaging of respiratory function.. · Proper selection of technical parameters customized to the clinical question and standardized terminology for the precise description and interpretation of the imaging signs regarding patient history determine its diagnostic accuracy.. · In dyspnea lung US differentiates pneumothorax, lung edema, pneumonia, pulmonary embolism, atelectasis and pleural effusion.. · In intensive care, lung US allows monitoring of lung ventilation and fluid administration.. · It saves radiation exposure in serial follow-up, in pregnancy and pediatric radiology..
CITATION FORMAT
· Radzina M, Biederer J, Ultrasonography of the Lung. Fortschr Röntgenstr 2019; 191: 909 - 923.
Topics: Acute Disease; Chronic Disease; Humans; Lung; Lung Diseases; Pleural Diseases; Point-of-Care Testing; Pulmonary Embolism; Thoracic Wall; Ultrasonography
PubMed: 30947352
DOI: 10.1055/a-0881-3179 -
Monaldi Archives For Chest Disease =... Nov 2022Oxygen is probably the most commonly prescribed drug in the emergency setting and is a life-saving modality as well. However, like any other drug, oxygen therapy may... (Review)
Review
Oxygen is probably the most commonly prescribed drug in the emergency setting and is a life-saving modality as well. However, like any other drug, oxygen therapy may also lead to various adverse effects. Patients with chronic obstructive pulmonary disease (COPD) may develop hypercapnia during supplemental oxygen therapy, particularly if uncontrolled. The risk of hypercapnia is not restricted to COPD only; it has also been reported in patients with morbid obesity, asthma, cystic fibrosis, chest wall skeletal deformities, bronchiectasis, chest wall deformities, or neuromuscular disorders. However, the risk of hypercapnia should not be a deterrent to oxygen therapy in hypoxemic patients with chronic lung diseases, as hypoxemia may lead to life-threatening cardiovascular complications. Various mechanisms leading to the development of oxygen-induced hypercapnia are the abolition of 'hypoxic drive', loss of hypoxic vasoconstriction and absorption atelectasis leading to an increase in dead-space ventilation and Haldane effect. The international guideline recommends a target oxygen saturation of 88% to 92% in patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) and other chronic lung diseases at risk of hypercapnia. Oxygen should be administered only when oxygen saturation is below 88%. We searched PubMed, EMBASE, and the CINAHL from inception to June 2022. We used the following search terms: "Hypercapnia", "Oxygen therapy in COPD", "Oxygen-associated hypercapnia", "oxygen therapy", and "Hypoxic drive". All types of study are selected. This review will focus on the physiological mechanisms of oxygen-induced hypercapnia and its clinical implications.
Topics: Humans; Oxygen; Hypercapnia; Pulmonary Disease, Chronic Obstructive; Oxygen Inhalation Therapy; Lung Diseases; Hypoxia
PubMed: 36412131
DOI: 10.4081/monaldi.2022.2399 -
European Respiratory Review : An... Dec 2021Coronavirus disease 2019 (COVID-19) pneumonia is an evolving disease. We will focus on the development of its pathophysiologic characteristics over time, and how these... (Review)
Review
Coronavirus disease 2019 (COVID-19) pneumonia is an evolving disease. We will focus on the development of its pathophysiologic characteristics over time, and how these time-related changes determine modifications in treatment. In the emergency department: the peculiar characteristic is the coexistence, in a significant fraction of patients, of severe hypoxaemia, near-normal lung computed tomography imaging, lung gas volume and respiratory mechanics. Despite high respiratory drive, dyspnoea and respiratory rate are often normal. The underlying mechanism is primarily altered lung perfusion. The anatomical prerequisites for PEEP (positive end-expiratory pressure) to work (lung oedema, atelectasis, and therefore recruitability) are lacking. In the high-dependency unit: the disease starts to worsen either because of its natural evolution or additional patient self-inflicted lung injury (P-SILI). Oedema and atelectasis may develop, increasing recruitability. Noninvasive supports are indicated if they result in a reversal of hypoxaemia and a decreased inspiratory effort. Otherwise, mechanical ventilation should be considered to avert P-SILI. In the intensive care unit: the primary characteristic of the advance of unresolved COVID-19 disease is a progressive shift from oedema or atelectasis to less reversible structural lung alterations to lung fibrosis. These later characteristics are associated with notable impairment of respiratory mechanics, increased arterial carbon dioxide tension ( ), decreased recruitability and lack of response to PEEP and prone positioning.
Topics: COVID-19; Humans; Lung; Positive-Pressure Respiration; Pulmonary Atelectasis; Respiration, Artificial; Respiratory Mechanics; SARS-CoV-2
PubMed: 34670808
DOI: 10.1183/16000617.0138-2021 -
Respiratory Medicine Oct 2021Setting the proper level of positive end-expiratory pressure (PEEP) is a cornerstone of lung protective ventilation. PEEP keeps the alveoli open at the end of... (Review)
Review
Setting the proper level of positive end-expiratory pressure (PEEP) is a cornerstone of lung protective ventilation. PEEP keeps the alveoli open at the end of expiration, thus reducing atelectrauma and shunt. However, excessive PEEP may contribute to alveolar overdistension. Electrical impedance tomography (EIT) is a non-invasive bedside tool that monitors in real-time ventilation distribution. Aim of this narrative review is summarizing the techniques for EIT-guided PEEP titration, while providing useful insights to enhance comprehension on advantages and limits of EIT for current and future users. EIT detects thoracic impedance to alternating electrical currents between pairs of electrodes and, through the analysis of its temporal and spatial variation, reconstructs a two-dimensional slice image of the lung depicting regional variation of ventilation and perfusion. Several EIT-based methods have been proposed for PEEP titration. The first described technique estimates the variations of regional lung compliance during a decremental PEEP trial, after lung recruitment. The optimal PEEP value is represented by the best compromise between lung collapse and overdistension. Later on, a second technique assessing alveolar recruitment by variation of the end-expiratory lung impedance was validated. Finally, the global inhomogeneity index and the regional ventilation delay, two EIT-derived parameters, showed promising results selecting the optimal PEEP value as the one that presents the lowest global inhomogeneity index or the lowest regional ventilation delay. In conclusion EIT represents a promising technique to individualize PEEP in mechanically ventilated patients. Whether EIT is the best technique for this purpose and the overall influence of personalizing PEEP on clinical outcome remains to be determined.
Topics: Electric Impedance; Humans; Lung; Monitoring, Physiologic; Point-of-Care Testing; Positive-Pressure Respiration; Pulmonary Atelectasis; Respiratory Distress Syndrome; Tomography
PubMed: 34352563
DOI: 10.1016/j.rmed.2021.106555 -
JAMA Jun 2019An intraoperative higher level of positive end-expiratory positive pressure (PEEP) with alveolar recruitment maneuvers improves respiratory function in obese patients... (Comparative Study)
Comparative Study Randomized Controlled Trial
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.
Topics: Adult; Anesthesia, General; Body Mass Index; Female; Humans; Intraoperative Care; Lung Diseases; Male; Middle Aged; Obesity; Pleural Diseases; Positive-Pressure Respiration; Postoperative Complications; Pulmonary Atelectasis; Respiratory Insufficiency; Surgical Procedures, Operative; Tidal Volume; Treatment Outcome
PubMed: 31157366
DOI: 10.1001/jama.2019.7505 -
JAMA Surgery Jul 2019Incentive spirometers (ISs) were developed to reduce atelectasis and are in widespread clinical use. However, without IS use adherence data, the effectiveness of IS... (Randomized Controlled Trial)
Randomized Controlled Trial
IMPORTANCE
Incentive spirometers (ISs) were developed to reduce atelectasis and are in widespread clinical use. However, without IS use adherence data, the effectiveness of IS cannot be determined.
OBJECTIVE
To evaluate the effect of a use-tracking IS reminder on patient adherence and clinical outcomes following coronary artery bypass grafting (CABG) surgery.
DESIGN, SETTING, AND PARTICIPANTS
This randomized clinical trial was conducted from June 5, 2017, to December 29, 2017, at a tertiary referral teaching hospital and included 212 patients who underwent CABG, of whom 160 participants were randomized (intent to treat), with 145 completing the study per protocol. Participants were stratified by surgical urgency (elective vs nonelective) and sex (men vs women).
INTERVENTIONS
A use-tracking, IS add-on device (SpiroTimer) with an integrated use reminder bell recorded and timestamped participants' inspiratory breaths. Patients were randomized by hourly reminder "bell on" (experimental group) or "bell off" (control group).
MAIN OUTCOMES AND MEASURES
Incentive spirometer use was recorded for the entire postoperative stay and compared between groups. Radiographic atelectasis severity (score, 0-10) was the primary clinical outcome. Secondary respiratory and nonrespiratory outcomes were also evaluated.
RESULTS
A total of 145 per-protocol participants (112 men [77%]; mean age, 69 years [95% CI, 67-70]; 90 [62%] undergoing a nonelective procedure) were evaluated, with 74 (51.0%) in the bell off group and 71 (49.0%) in the bell on group. The baseline medical and motivation-to-recover characteristics of the 2 groups were similar. The mean number of daily inspiratory breaths was greater in bell on (35; 95% CI, 29-43 vs 17; 95% CI, 13-23; P < .001). The percentage of recorded hours with an inspiratory breath event was greater in bell on (58%; 95% CI, 51-65 vs 28%; 95% CI, 23-32; P < .001). Despite no differences in the first postoperative chest radiograph mean atelectasis severity scores (2.3; 95% CI, 2.0-2.6 vs 2.4; 95% CI, 2.2-2.7; P = .48), the mean atelectasis severity scores for the final chest radiographs conducted before discharge were significantly lower for bell on than bell off group (1.5; 95% CI, 1.3-1.8 vs 1.8; 95% CI, 1.6-2.1; P = .04). Of those with early postoperative fevers, fever duration was shorter for bell on (3.2 hours; 95% CI, 2.3-4.6 vs 5.2 hours; 95% CI, 3.9-7.0; P = .04). Having the bell turned on reduced noninvasive positive pressure ventilation use rates (37.2%; 95% CI, 24.1%-52.5% vs 19.2%; 95% CI, 10.2%-33.0%; P = .03) for participants undergoing nonelective procedures. Bell on reduced the median postoperative length of stay (7 days; 95% CI, 6-9 vs 6 days; 95% CI, 6-7; P = .048) and the intensive care unit length of stay for patients undergoing nonelective procedures (4 days; 95% CI, 3-5 vs 3 days; 95% CI, 3-4; P = .02). At 6 months, the bell off mortality rate was higher than bell on (9% vs 0%, P = .048) for participants undergoing nonelective procedures.
CONCLUSIONS AND RELEVANCE
The incentive spirometer reminder improved patient adherence, atelectasis severity, early postoperative fever duration, noninvasive positive pressure ventilation use, ICU and length of stay, and 6-month mortality in certain patients. With the reminder, IS appears to be clinically effective when used appropriately.
TRIAL REGISTRATION
ClinicalTrials.gov identifier: NCT02952027.
Topics: Aged; Coronary Artery Bypass; Coronary Artery Disease; Female; Follow-Up Studies; Humans; Incidence; Intensive Care Units; Male; Patient Compliance; Postoperative Complications; Pulmonary Atelectasis; Retrospective Studies; Spirometry; Survival Rate; United States
PubMed: 30969332
DOI: 10.1001/jamasurg.2019.0520