High Levels Of Positive End-expiratory Pressure Research Articles

Lung donor bronchoalveolar lavage positivity: Incidence, risk factors, and lung transplant recipients’ outcome

BackgroundInconsistent data exists regarding the risk factors for bronchoalveolar lavage (BAL) positivity in lung donors, the incidence of donor-derived infections (DDI), and the effect of BAL positivity on lung transplant (LuTx) recipients’ outcome. MethodsA retrospective analysis was conducted on consecutive LuTx at a single center from January 2016 to December 2022. Donors’ data, including characteristics, graft function and BAL samples were collected pre-procurement. Recipients underwent BAL before LuTx and about the 3rd, 7th and 14th day after LuTx. A DDI was defined as BAL positivity (bacterial growth ≥104 colony forming units) for identical bacterial species between donor and recipient. Recipients’ pre-operative characteristics, intra-operative management, and post-operative outcomes were assessed. Two recipient cohorts were identified based on lung colonization status before undergoing LuTx. ResultsOut of 188 LuTx procedures performed, 169 were analyzed. Thirty-six percent of donors’ BAL tested positive. Donors’ characteristics and graft function at procurement were not associated with BAL positivity. Fourteen DDI were detected accounting for 23% of recipients receiving a graft with a positive BAL. Only among uncolonized recipients, receiving a graft with positive BAL is associated with higher likelihood of requiring invasive ventilation at 72 hours after LuTx on higher positive end-expiratory pressure levels having lower PaO2/FiO2, prolonged duration of mechanical ventilation and longer ICU stay. No difference in hospital length of stay was observed. ConclusionsReceiving a graft with a positive BAL, which is poorly predicted by donors’ characteristics, carries the risk of developing a DDI and is associated to a worse early graft function among uncolonized recipients.

Decision day – A retrospective analysis of COVID-19 patients treated with high PEEP non-invasive ventilation

Background and objectives. This retrospective analysis investigates the effect of high levels of Positive End-Expiratory Pressure (PEEP) during Non-Invasive Ventilation (NIV) in patients with COVID 19 Acute Respiratory Distress Syndrome (ARDS). Materials and methods. In the University Hospital Center Zagreb from October 2021 to February 2022, the study analyzed data from 97 patients who received NIV for acute respiratory support during ICU stay. The effect of NIV on survival, the length of stay in the ICU as well as the duration of the support itself was investigated. Results. Results show that despite low mortality in patients with NIV support, mortality is quite high in patients who required intubation. There is also a divergence of the respiratory support level parameter after the 3rd day on NIV, which suggests that moment as pivotal for assessing the continuation of NIV support. Conclusions. The results show that high level PEEP is a viable option for starting respiratory support in ARDS, but also the importance of timely assessment to optimize patient outcomes.

Positive End-Expiratory Pressure Levels in Adult Patients With Acute Lung Injury and Acute Respiratory Distress Syndrome

Positive End-Expiratory Pressure Levels in Adult Patients With Acute Lung Injury and Acute Respiratory Distress Syndrome

The Effects of Positive End Expiratory Pressure and Lung Volume on Diaphragm Thickness and Thickening

Introduction: Diaphragm dysfunction is common in patients undergoing mechanical ventilation. The application of positive end-expiratory pressure (PEEP) and the varying end-expiratory lung volume cause changes in diaphragm geometry. We aimed to assess the impact of the level of PEEP and lung inflation on diaphragm thickness, thickening fraction and displacement. Methods: An observational study in a mixed medical and surgical ICU was conducted. The patients underwent a PEEP-titration trial with the application of three random levels of PEEP: 0 cmH2O (PEEP0), 8 cmH2O (PEEP8) and 15 cmH2O (PEEP15). At each step, the indices of respiratory effort were assessed, together with arterial blood and diaphragm ultrasound; end-expiratory lung volume was measured. Results: 14 patients were enrolled. The tidal volume, diaphragm displacement and thickening fraction were significantly lower with higher levels of PEEP, while both the expiratory and inspiratory thickness increased with higher PEEP levels. The inspiratory effort, as evaluated by the esophageal pressure swing, was unchanged. Both the diaphragm thickening fraction and displacement were significantly correlated with inspiratory effort in the whole dataset. For both measurements, the correlation was stronger at lower levels of PEEP. The difference in the diaphragm thickening fraction during tidal breathing between PEEP 15 and PEEP 0 was negatively related to the change in the functional residual capacity and the change in alveolar dead space. Conclusions: Different levels of PEEP significantly modified the diaphragmatic thickness and thickening fraction, showing a PEEP-induced decrease in the diaphragm contractile efficiency. When using ultrasound to assess diaphragm size and function, the potential effect of lung inflation should be taken into account.

Effects of Individualised High Positive End-Expiratory Pressure and Crystalloid Administration on Postoperative Pulmonary Function in Patients Undergoing Robotic-Assisted Radical Prostatectomy: A Prospective Randomised Single-Blinded Pilot Study

Robotic-assisted laparoscopic prostatectomy (RALP) is typically conducted in steep Trendelenburg position (STP). The aim of the study was to evaluate whether crystalloid administration and individual management of positive end-expiratory pressure (PEEP) improve peri- and post-operative pulmonary function in patients undergoing RALP. Prospective randomised single-centre single-blinded explorative study. Patients were either allocated to a standard PEEP (5 cmH2O) group or an individualised high PEEP group. Furthermore, each group was divided into a liberal and a restrictive crystalloid group (8 vs. 4 mL/kg/h predicted body weight). Individualised PEEP levels were determined by means of preoperative recruitment manoeuvre and PEEP titration in STP. Informed consent was obtained from 98 patients scheduled for elective RALP. The following intraoperative parameters were analysed in each of the four study groups: ventilation setting (peak inspiratory pressure [PIP], plateau pressure, driving pressure [Pdriv], lung compliance [LC] and mechanical power [MP]) and postoperative pulmonary function (bed-side spirometry). The spirometric parameters Tiffeneau index (FEV1/FVC ratio) and mean forced expiratory flow (FEF25-75) were measured pre- and post-operatively. Data are shown as mean ± standard deviation (SD), and groups were compared with ANOVA. A p-value of <0.05 was considered significant. The two individualised high PEEP groups (mean PEEP 15.5 [±1.71 cmH2O]) showed intraoperative significantly higher PIP, plateau pressure and MP levels but significantly decreased Pdriv and increased LC. On the first and second postoperative day, patients with individualised high PEEP levels had a significantly higher mean Tiffeneau index and FEF25-75. Perioperative oxygenation and ventilation and postoperative spirometric parameters were not influenced by restrictive or liberal crystalloid infusion in either of the two respective PEEP groups. Individualised high PEEP levels (≥14 cmH2O) during RALP improved intraoperative blood oxygenation and resulted in more lung-protective ventilation. Furthermore, postoperative pulmonary function was improved for up to 48 h after surgery in the sum of the two individualised high PEEP groups. Restrictive crystalloid infusion during RALP seemed to have no effect on peri- and post-operative oxygenation and pulmonary function.

Minimizing Lung Injury During Laparoscopy in Head-Down Tilt: A Physiological Cohort Study.

Increased intra-abdominal pressure during laparoscopy induces atelectasis. Positive end-expiratory pressure (PEEP) can alleviate atelectasis but may cause hyperinflation. Cyclic opening of collapsed alveoli and hyperinflation can lead to ventilator-induced lung injury and postoperative pulmonary complications. We aimed to study the effect of PEEP on atelectasis, lung stress, and hyperinflation during laparoscopy in the head-down (Trendelenburg) position. An open-label, repeated-measures, interventional, physiological cohort trial was designed. All participants were recruited from a single tertiary Belgian university hospital. Twenty-three nonobese patients scheduled for laparoscopy in the Trendelenburg position were recruited.We applied a decremental PEEP protocol: 15 (high), 10 and 5 (low) cm H 2 O. Atelectasis was studied with the lung ultrasound score, the end-expiratory transpulmonary pressure, the arterial oxygen partial pressure to fraction of inspired oxygen concentration (P ao2 /Fi o2 ) ratio, and the dynamic respiratory system compliance. Global hyperinflation was evaluated by dead space volume, and regional ventilation was evaluated by lung ultrasound. Lung stress was estimated using the transpulmonary driving pressure and dynamic compliance. Data are reported as medians (25th-75th percentile). At 15, 10, and 5 cm H 2 O PEEP, the respective measurements were: lung ultrasound scores (%) 11 (0-22), 27 (11-39), and 53 (42-61) ( P < .001); end-expiratory transpulmonary pressures (cm H 2 O) 0.9 (-0.6 to 1.7), -0.3 (-2.0 to 0.7), and -1.9 (-4.6 to -0.9) ( P < .001); P ao2 /Fi o2 ratios (mm Hg) 471 (435-538), 458 (410-537), and 431 (358-492) ( P < .001); dynamic respiratory system compliances (mL/cm H 2 O) 32 (26-36), 30 (25-34), and 27 (22-30) ( P < .001); driving pressures (cm H 2 O) 8.2 (7.5-9.5), 9.3 (8.5-11.1), and 11.0 (10.3-12.2) ( P < .001); and alveolar dead space ventilation fractions (%) 10 (9-12), 10 (9-12), and 9 (8-12) ( P = .23). The lung ultrasound score was similar between apical and basal lung regions at each PEEP level ( P = .76, .37, and .76, respectively). Higher PEEP levels during laparoscopy in the head-down position facilitate lung-protective ventilation. Atelectasis and lung stress are reduced in the absence of global alveolar hyperinflation.

Biological impact of restrictive and liberal fluid strategies at low and high PEEP levels on lung and distal organs in experimental acute respiratory distress syndrome.

Background: Fluid regimens in acute respiratory distress syndrome (ARDS) are conflicting. The amount of fluid and positive end-expiratory pressure (PEEP) level may interact leading to ventilator-induced lung injury (VILI). We therefore evaluated restrictive and liberal fluid strategies associated with low and high PEEP levels with regard to lung and kidney damage, as well as cardiorespiratory function in endotoxin-induced ARDS. Methods: Thirty male Wistar rats received an intratracheal instillation of Escherichia coli lipopolysaccharide. After 24h, the animals were anesthetized, protectively ventilated (VT = 6ml/kg), and randomized to restrictive (5ml/kg/h) or liberal (40ml/kg/h) fluid strategies (Ringer lactate). Both groups were then ventilated with PEEP = 3 cmH2O (PEEP3) and PEEP = 9 cmH2O (PEEP9) for 1h (n = 6/group). Echocardiography, arterial blood gases, and lung mechanics were evaluated throughout the experiments. Histologic analyses were done on the lungs, and molecular biology was assessed in lungs and kidneys using six non-ventilated animals with no fluid therapy. Results: In lungs, the liberal group showed increased transpulmonary plateau pressure compared with the restrictive group (liberal, 23.5 ± 2.9 cmH2O; restrictive, 18.8 ± 2.3cmH2O, p = 0.046) under PEEP = 9 cmH2O. Gene expression associated with inflammation (interleukin [IL]-6) was higher in the liberal-PEEP9 group than the liberal-PEEP3 group (p = 0.006) and restrictive-PEEP9 (p = 0.012), Regardless of the fluid strategy, lung mechanical power and the heterogeneity index were higher, whereas birefringence for claudin-4 and zonula-ocludens-1 gene expression were lower in the PEEP9 groups. Perivascular edema was higher in liberal groups, regardless of PEEP levels. Markers related to damage to epithelial cells [club cell secreted protein (CC16)] and the extracellular matrix (syndecan) were higher in the liberal-PEEP9 group than the liberal-PEEP3 group (p = 0.010 and p = 0.024, respectively). In kidneys, the expression of IL-6 and neutrophil gelatinase-associated lipocalin was higher in PEEP9 groups, regardless of the fluid strategy. For the liberal strategy, PEEP = 9 cmH2O compared with PEEP = 3 cmH2O reduced the right ventricle systolic volume (37%) and inferior vena cava collapsibility index (45%). Conclusion: The combination of a liberal fluid strategy and high PEEP led to more lung damage. The application of high PEEP, regardless of the fluid strategy, may also be deleterious to kidneys.

Modelling patient specific cardiopulmonary interactions

Mechanical ventilation is well known for having detrimental effects on the cardiovascular system, particularly when using high positive end-expiratory pressure. High positive end-expiratory pressure levels cause a decrease in stroke volume, which, under normal conditions, usually bring about a decrease in stressed blood volume. Stressed blood volume, defined as the total pressure generating volume of the cardiovascular system, has been shown to be a potential index of fluid responsiveness, making it a potentially important diagnostic tool. Generally, respiratory and haemodynamic care are provided independently of one another. However, that positive end-expiratory pressure alters both stroke volume and stressed blood volume suggests both the pulmonary and cardiovascular state should be conjointly optimised and used to guide positive end-expiratory pressure. However, the complex and patient-specific nature of cardiopulmonary interactions which occur during mechanical ventilation presents a challenge for accurate modelling of respiratory and cardiovascular interactions required to better optimise care. Previous models attempting to incorporate cardiopulmonary interactions have suffered from poor reliability at higher PEEP levels, largely due to an exaggerated effect of intrathoracic pressure on the cardiovascular system. A new parameter, alpha, is added to a previously validated cardiopulmonary model, to modulate the percentage of intrathoracic pressure applied to the vena cava and left ventricle. The new parameter aims to increase reliability under high PEEP conditions as well as provide a patient specific solution to modelling cardiopulmonary interactions. The results from the identified optimal alpha are compared to the original model to investigate how this new parameter may be used to create a more patient-specific cardiopulmonary model, which would be better suited for guidance of care in the ICU.

PEEP-FiO2 table versus EIT to titrate PEEP in mechanically ventilated patients with COVID-19-related ARDS

RationaleIt is unknown how to titrate positive end-expiratory pressure (PEEP) in patients with COVID-19-related acute respiratory distress syndrome (ARDS). Guidelines recommend the one-size-fits-all PEEP-FiO2 table. In this retrospective cohort study, an electrical impedance tomography (EIT)-guided PEEP trial was used to titrate PEEP.ObjectivesTo compare baseline PEEP according to the high PEEP-FiO2 table and personalized PEEP following an EIT-guided PEEP trial.MethodsWe performed an EIT-guided decremental PEEP trial in patients with moderate-to-severe COVID-19-related ARDS upon intensive care unit admission. PEEP was set at the lowest PEEP above the intersection of curves representing relative alveolar overdistention and collapse. Baseline PEEP was compared with PEEP set according to EIT. We identified patients in whom the EIT-guided PEEP trial resulted in a decrease or increase in PEEP of ≥ 2 cmH2O.Measurements and main resultsWe performed a PEEP trial in 75 patients. In 23 (31%) patients, PEEP was decreased ≥ 2 cmH2O, and in 24 (32%) patients, PEEP was increased ≥ 2 cmH2O. Patients in whom PEEP was decreased had improved respiratory mechanics and more overdistention in the non-dependent lung region at higher PEEP levels. These patients also had a lower BMI, longer time between onset of symptoms and intubation, and higher incidence of pulmonary embolism. Oxygenation improved in patients in whom PEEP was increased.ConclusionsAn EIT-guided PEEP trial resulted in a relevant change in PEEP in 63% of patients. These results support the hypothesis that PEEP should be personalized in patients with ARDS.

Evolution of respiratory system compliance and potential for lung recruitment in COVID-19–induced acute respiratory distress syndrome

BackgroundCoronavirus disease 2019 (COVID-19) has been frequently complicated by severe acute respiratory distress syndrome (ARDS) with prolonged invasive ventilation. While respiratory system compliance and lung recruitability have been described within the first days after ICU admission, data about their longitudinal changes are still limited. Therefore, we conducted this study to assess the evolution of respiratory system compliance and lung recruitability in patients with COVID-19–related ARDS. MethodWe conducted a prospective single-center study in patients admitted for COVID-19–related ARDS during the first wave of the pandemic, from March 16, 2020 to April 10, 2020. Respiratory system compliance was calculated daily at clinical positive end-expiratory pressure (PEEP) during passive breathing. The potential for lung recruitment was assessed by measuring the volume derecruited between PEEP 15 cmH2O and 5 cmH2O, and using the calculation of the recruitment-to-inflation ratio (R/I ratio). Recruitable lung was considered when the R/I ratio was at least 0.5. The primary outcome was the evolution of respiratory mechanics over time. The secondary outcome was the evolution of lung recruitability over time. ResultsThirty-two patients were included in this study. The respiratory mechanics were assessed 222 times (7 ± 5 times per patient). Respiratory system compliance at clinical PEEP was 29.1 mL/cmH2O (interquartile range [IQR]: 24.1–33.9 mL/cmH2O) and decreased significantly over time (P <0.0001). Lung recruitability was assessed in 22 out of the 32 patients (60 assessments). The median volume derecruited between PEEP 15 cmH2O and 5 cmH2O was 246.8 mL (IQR: 180.8–352.2 mL) and the median R/I ratio was 0.56 (IQR: 0.39–0.73). Neither changed significantly over time. The proportion of patients with recruitable lung was 50.0% (6/12) within the first 3 days after intubation, 69.2% (9/13) between day 4 and day 7, and 66.7% (8/12) after day 7 (P=0.7934). ConclusionsIn our cohort, respiratory system compliance was low and decreased over time. The potential for lung recruitment was high and persisted despite prolonged mechanical ventilation, suggesting that maintaining high PEEP levels in the later course of COVID-19 could be adequate.

Dynamic positive end-expiratory pressure strategies using time and pressure recruitment at birth reduce early expression of lung injury in preterm lambs.

Positive end-expiratory pressure (PEEP) is critical to the preterm lung at birth, but the optimal PEEP level remains uncertain. The objective of this study was to determine the effect of maximum PEEP levels at birth on the physiological and injury response in preterm lambs. Steroid-exposed preterm lambs (124-127 days gestation; n = 65) were randomly assigned from birth to either 1) positive pressure ventilation (PPV) at 8 cmH2O PEEP or 3-min dynamic stepwise PEEP strategy (DynPEEP), with either 2) 20 cmH2O maximum PEEP (10 PEEP second steps) or 3) 14 cmH2O maximum PEEP (20-s steps), all followed by standardized PPV for 90 min. Lung mechanics, gas exchange, regional ventilation and aeration (electrical impedance tomography), and histological and molecular measures of lung injury were compared between groups. Dynamic compliance was greatest using a maximum 20 cmH2O (DynPEEP). There were no differences in gas exchange, end-expiratory volume, and ventilator requirements. Regional ventilation became more uniform with time following all PEEP strategies. For all groups, gene expression of markers of early lung injury was greater in the gravity nondependent lung, and inversely related to the magnitude of PEEP, being lowest in the 20 cmH2O DynPEEP group overall. PEEP levels had no impact on lung injury in the dependent lung. Transient high maximum PEEP levels using dynamic PEEP strategies may confer more lung protection at birth.

High PEEP Levels during CPR Improve Ventilation without Deleterious Haemodynamic Effects in Pigs.

Background: Invasive ventilation during cardiopulmonary resuscitation (CPR) is very complex due to unique thoracic pressure conditions. Current guidelines do not provide specific recommendations for ventilation during ongoing chest compressions regarding positive end-expiratory pressure (PEEP). This trial examines the cardiopulmonary effects of PEEP application during CPR. Methods: Forty-two German landrace pigs were anaesthetised, instrumented, and randomised into six intervention groups. Three PEEP levels (0, 8, and 16 mbar) were compared in high standard and ultralow tidal volume ventilation. After the induction of ventricular fibrillation, mechanical chest compressions and ventilation were initiated and maintained for thirty minutes. Blood gases, ventilation/perfusion ratio, and electrical impedance tomography loops were taken repeatedly. Ventilation pressures and haemodynamic parameters were measured continuously. Postmortem lung tissue damage was assessed using the diffuse alveolar damage (DAD) score. Statistical analyses were performed using SPSS, and p values <0.05 were considered significant. Results: The driving pressure (Pdrive) showed significantly lower values when using PEEP 16 mbar than when using PEEP 8 mbar (p = 0.045) or PEEP 0 mbar (p < 0.001) when adjusted for the ventilation mode. Substantially increased overall lung damage was detected in the PEEP 0 mbar group (vs. PEEP 8 mbar, p = 0.038; vs. PEEP 16 mbar, p = 0.009). No significant differences in mean arterial pressure could be detected. Conclusion: The use of PEEP during CPR seems beneficial because it optimises ventilation pressures and reduces lung damage without significantly compromising blood pressure. Further studies are needed to examine long-term effects in resuscitated animals.

Recruitable alveolar collapse and overdistension during laparoscopic gynecological surgery and mechanical ventilation: a prospective clinical study

BackgroundLaparoscopic surgery in Trendelenburg position may impede mechanical ventilation (MV) due to positioning and high intra-abdominal pressure. We sought to identify the positive end-expiratory pressure (PEEP) levels necessary to counteract atelectasis formation (“Open-Lung-PEEP”) and to provide an equal balance between overdistension and alveolar collapse (“Best-Compromise-PEEP”).MethodsIn 30 patients undergoing laparoscopic gynecological surgery, relative overdistension and alveolar collapse were assessed with electrical impedance tomography (EIT) during a decremental PEEP trial ranging from 20 to 4 cmH2O in supine position without capnoperitoneum and in Trendelenburg position with capnoperitoneum.ResultsIn supine position, the median Open-Lung-PEEP was 12 (8–14) cmH2O with 8.7 (4.7–15.5)% of overdistension and 1.7 (0.4–2.2)% of collapse. Best-Compromise-PEEP was 8 (6.5–10) cmH2O with 4.2 (2.4–7.2)% of overdistension and 5.1 (3.9–6.5)% of collapse. In Trendelenburg position with capnoperitoneum, Open-Lung-PEEP was 18 (18–20) cmH 2 O (p < 0.0001 vs supine position) with 1.8 (0.5–3.9)% of overdistension and 0 (0–1.2)% of collapse and Best-Compromise-PEEP was 18 (16–20) cmH2O (p < 0.0001 vs supine position) with 1.5 (0.7–3.0)% of overdistension and 0.2 (0–2.7)% of collapse. Open-Lung-PEEP and Best-Compromise-PEEP were positively correlated with body mass index during MV in supine position but not in Trendelenburg position.ConclusionThe PEEP levels required for preventing alveolar collapse and for balancing collapse and overdistension in Trendelenburg position with capnoperitoneum were significantly higher than those required for achieving the same goals in supine position without capnoperitoneum. Even with high PEEP levels, alveolar overdistension was negligible during MV in Trendelenburg position with capnoperitoneum.Trial registrationThis study was prospectively registered at German Clinical Trials registry (DRKS00016974).

Intraoperative protective mechanical ventilation in patients requiring emergency abdominal surgery: the multicentre prospective randomised IMPROVE-2 study protocol

IntroductionEmergency abdominal surgery is associated with a high risk of postoperative complications. One of the most serious is postoperative respiratory failure (PRF), with reported rates up to 20%–30% and attributable...

Electrical Impedance Tomography to Set Positive End Expiratory Pressure During Pediatric Extracorporeal Membrane Oxygenation for Respiratory Failure... Is it Feasible?

Electrical Impedance Tomography to Set Positive End Expiratory Pressure During Pediatric Extracorporeal Membrane Oxygenation for Respiratory Failure... Is it Feasible?

Периоперационная протективная искусственная вентиляция легких при лапароскопических операциях у пациентов с ожирением

Актуальность. Пациенты с ожирением являются основной группой риска для формирования резорбционных ателектазов и возникновения послеоперационных легочных осложнений. Цель исследования: исследовать эффективность и безопасность принципов протективной искусственной вентиляции легких (ИВЛ) у пациентов с ожирением при абдоминальных лапароскопических операциях. На сегодняшний день доказано, что резорбционные ателектазы формируются у 90 % пациентов, которым проводится общая анестезия с ИВЛ. На фоне повышенного внутрибрюшного давления и гиповентиляции базальных отделов легких ателектазирование еще больше прогрессирует и может привести к существенным изменениям респираторной механики и гипоксемии. Основные компоненты протективной ИВЛ включают в себя: использование небольших дыхательных объемов, положительного давления конца выдоха (ПДКВ) выше физиологического уровня и проведение интраоперационного альвеолярного рекрутмента (аРМ). Материалы и методы. Всего было 24 пациента, которые были разделены на 3 группы: контрольную (ПДКВ5) и две основные (ПДКВ (10)/аРМ + ПДКВ (10)). В 4 контрольных точках общей анестезии исследовались: статический тораколегочный комплайенс, среднее внутригрудное давление и среднее артериальное давление. Результаты. Проанализировав статический тораколегочный комплайенс, лучшие результаты мы наблюдали в группе, в которой проводились аРМ в сочетании с последующим повышением ПДКВ. Относительно среднего внутригрудного давления и среднего артериального давления существенных различий и негативных изменений во всех группах пациентов не наблюдалось. Выводы. Интраоперационное сочетание альвеолярных рекрутментов и последующего повышенного уровня ПДКВ показывает увеличение тораколегочного комплайенса и может свидетельствовать об уменьшении процента ателектазированной легочной ткани. В основной группе пациентов не наблюдалось гемодинамической нестабильности после проведения аРМ и установки ПТКВ. Предварительно данные методы можно считать безопасными при лапароскопических операциях.

Mechanical ventilation in COVID‐19: A physiological perspective

New Findings What is the topic of this review? This review presents the fundamental concepts of respiratory physiology and pathophysiology, with particular reference to lung mechanics and the pulmonary phenotype associated with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection and subsequent coronavirus disease 2019 (COVID‐19) pneumonia. What advances does it highlight? The review provides a critical summary of the main physiological aspects to be considered for safe and effective mechanical ventilation in patients with severe COVID‐19 in the intensive care unit. Severe respiratory failure from coronavirus disease 2019 (COVID‐19) pneumonia not responding to non‐invasive respiratory support requires mechanical ventilation. Although ventilation can be a life‐saving therapy, it can cause further lung injury if airway pressure and flow and their timing are not tailored to the respiratory system mechanics of the individual patient. The pathophysiology of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection can lead to a pattern of lung injury in patients with severe COVID‐19 pneumonia typically associated with two distinct phenotypes, along a temporal and pathophysiological continuum, characterized by different levels of elastance, ventilation‐to‐perfusion ratio, right‐to‐left shunt, lung weight and recruitability. Understanding the underlying pathophysiology, duration of symptoms, radiological characteristics and lung mechanics at the individual patient level is crucial for the appropriate choice of mechanical ventilation settings to optimize gas exchange and prevent further lung injury. By critical analysis of the literature, we propose fundamental physiological and mechanical criteria for the selection of ventilation settings for COVID‐19 patients in intensive care units. In particular, the choice of tidal volume should be based on obtaining a driving pressure < 14 cmH2O, ensuring the avoidance of hypoventilation in patients with preserved compliance and of excessive strain in patients with smaller lung volumes and lower lung compliance. The level of positive end‐expiratory pressure (PEEP) should be informed by the measurement of the potential for lung recruitability, where patients with greater recruitability potential may benefit from higher PEEP levels. Prone positioning is often beneficial and should be considered early. The rationale for the proposed mechanical ventilation settings criteria is presented and discussed.

How do high and low positive end-expiratory pressure (PEEP) levels compare for mechanically ventilated adults with acute lung injury and acute respiratory distress syndrome?

How do high and low positive end-expiratory pressure (PEEP) levels compare for mechanically ventilated adults with acute lung injury and acute respiratory distress syndrome?

Exploring prediction model and survival strategies for pulmonary hemorrhage in premature infants: a single-center, retrospective study.

BackgroundPulmonary hemorrhage is a potentially fatal event especially for preterm infants, which can lead to serious complications and even death. Many risk factors have been associated with the development of massive pulmonary hemorrhage. However, there is still no effective strategy to prevent massive pulmonary hemorrhage. The purpose of this study is to explore prediction model and survival strategies for massive pulmonary hemorrhage in premature infants.MethodsIn this retrospective study, we included all premature infants with birth weight <1,500 g who were hospitalized in our neonatal intensive care unit (NICU) between January 01 2010 and December 31 2019.ResultsOf 599 preterm infants, 51 developed massive pulmonary hemorrhage. The logistic regression analysis showed that patent ductus arteriosus [odds ratio (OR) =11.4, 95% confidence interval (CI): 4.79–27.0, P<0.0001], coagulopathy (OR =6.56, 95% CI: 2.83–15.2, P<0.0001), and 10-minute Apgar Score (OR =0.52, 95% CI: 0.37–0.73, P=0.0001) were risk factors for massive pulmonary hemorrhage. Whether or not surfactant is used, the positive predictive value of combined patent ductus arteriosus and coagulopathy for predicting massive pulmonary hemorrhage was 68.9% and 70.4%, respectively. Of the 51 preterm infants with massive pulmonary hemorrhage, 25 died and 26 survived. The survivors group had higher positive end-expiratory pressure compared with the deceased group after the onset of massive pulmonary hemorrhage. After adjusting for potential risk factors, the multiple logistic regression analysis showed that higher positive end-expiratory pressure levels are closely related to survival.ConclusionsPatent ductus arteriosus combined with coagulopathy has a high predictive value for massive pulmonary hemorrhage. Higher positive end-expiratory pressure levels may reduce mortality in massive pulmonary hemorrhage.

Weaning patients with obesity from ventilatory support.

Obesity prevalence is increasing in most countries in the world. In the United States, 42% of the population is obese (body mass index (BMI) > 30) and 9.2% is obese class III (BMI > 40). One of the greatest challenges in critically ill patients with obesity is the optimization of mechanical ventilation. The goal of this review is to describe respiratory physiologic changes in patients with obesity and discuss possible mechanical ventilation strategies to improve respiratory function. Individualized mechanical ventilation based on respiratory physiology after a decremental positive end-expiratory pressure (PEEP) trial improves oxygenation and respiratory mechanics. In a recent study, mortality of patients with respiratory failure and obesity was reduced by about 50% when mechanical ventilation was associated with the use of esophageal manometry and electrical impedance tomography (EIT). Obesity greatly alters the respiratory system mechanics causing atelectasis and prolonged duration of mechanical ventilation. At present, novel strategies to ventilate patients with obesity based on individual respiratory physiology showed to be superior to those based on standard universal tables of mechanical ventilation. Esophageal manometry and EIT are essential tools to systematically assess respiratory system mechanics, safely adjust relatively high levels of PEEP, and improve chances for successful weaning.