Mechanical Ventilation in ARDS

Acute respiratory distress syndrome (ARDS) is a form of hypoxemic respiratory failure, which requires supplemental oxygen delivered by mechanical ventilation, either noninvasively or more commonly by invasive mechanical ventilation. Although not currently meeting the definition for ARDS, these patients may also use heated high-flow nasal cannula and can sometimes avoid invasive mechanical ventilation as a result. The avoidance of worsening acute lung injury using lung-protective ventilation is the first principle of invasive mechanical ventilation in these patients. Conventionally, this involves keeping the plateau pressure below 30 cm H2O by using low tidal volume ventilation, based on ideal body weight. Multiple observational series suggest that targeting a low driving pressure concurrently is also important. The determination of the optimal setting for positive end-expiratory pressure (PEEP) remains controversial. The mode of ventilation utilized may be either volume or pressure limited. It has been suggested that vigorous respiratory efforts can worsen lung injury and are best avoided whenever possible. Modes of ventilation such as airway pressure release ventilation lack evidence to support use and should not be used. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

Veno-venous ECMO

Extracorporeal membrane oxygenator support can be performed in a veno-arterial configuration to support cardiopulmonary dysfunction, or veno-venous configuration if cardiac function is satisfactory but pulmonary function is limiting. In this case you are asked to cannulate an obese 36-year-old man with ARDS for veno-venous ECMO at the bedside. Initially planning to use a double-lumen catheter from the neck, the patient's ventricular dysrhythmias associated with passing a wire convinced you that an alternate approach will be safer and you proceed with cannulating the right internal jugular vein and right femoral vein for inflow and outflow respectively. The options for cannulating for veno-venous ECMO and associated complexities are reviewed. © The Author(s), 2022. All rights reserved.

Combined extracorporeal CO2 removal and renal replacement therapy in a pregnant patient with COVID-19: a case report.

Background. Pregnant women are at high risk of Coronavirus disease 2019 (COVID-19) complications, including acute respiratory distress syndrome. Currently, one of the cornerstones in the treatment of this condition is lung-protective ventilation (LPV) with low tidal volumes. However, the occurrence of hypercapnia may limit this ventilatory strategy. So, different extracorporeal CO2 removal (ECCO2R) procedures have been developed. ECCO2R comprises a variety of techniques, including low-flow and high-flow systems, that may be performed with dedicated devices or combined with continuous renal replacement therapy (CRRT). Case description. Here, we report a unique case of a pregnant patient affected by COVID-19 who required extracorporeal support for multiorgan failure. While on LPV, because of the concomitant hypercapnia and acute kidney injury, the patient was treated with an ECCO2R membrane inserted in series after a hemofilter in a CRRT platform. This combined treatment reducing hypercapnia allowed LPV maintenance at the same time while providing kidney replacement and ensuring maternal and fetal hemodynamic stability. Adverse effects consisted of minor bleeding episodes due to the anticoagulation required to maintain the extracorporeal circuit patency. The patient's pulmonary and kidney function progressively recovered, permitting the withdrawal of any extracorporeal treatment. At the 25th gestational week, the patient underwent spontaneous premature vaginal delivery because of placental abruption. She gave birth to an 800-gram female baby, who three days later died because of multiorgan failure related to extreme prematurity. Conclusions. This case supports using ECCO2R-CRRT combined treatment as a suitable approach in the management of complex conditions, such as pregnancy, even in the case of severe COVID-19.

COVID-19-induced acute respiratory distress syndrome and challenges faced in management of young morbidly obese patient

In 2020, the World Health Organization described the SARS-CoV-2 virus (severe acute respiratory distress syndrome [ARDS]) for the first time. Millions of people were affected by the COVID virus worldwide, and many of them lost their lives too. Our center was also one health-care center that has played a significant role in managing severe ARDS patients secondary to COVID-19 infection. We want to outline the challenges faced by the respiratory therapist in managing a 24-year-old morbidly obese young male with severe ARDS due to COVID-19.

Extracorporeal Carbon Dioxide Removal: From Pathophysiology to Clinical Applications; Focus on Combined Continuous Renal Replacement Therapy.

Lung-protective ventilation (LPV) with low tidal volumes can significantly increase the survival of patients with acute respiratory distress syndrome (ARDS) by limiting ventilator-induced lung injuries. However, one of the main concerns regarding the use of LPV is the risk of developing hypercapnia and respiratory acidosis, which may limit the clinical application of this strategy. This is the reason why different extracorporeal CO2 removal (ECCO2R) techniques and devices have been developed. They include low-flow or high-flow systems that may be performed with dedicated platforms or, alternatively, combined with continuous renal replacement therapy (CRRT). ECCO2R has demonstrated effectiveness in controlling PaCO2 levels, thus allowing LPV in patients with ARDS from different causes, including those affected by Coronavirus disease 2019 (COVID-19). Similarly, the suitability and safety of combined ECCO2R and CRRT (ECCO2R-CRRT), which provides CO2 removal and kidney support simultaneously, have been reported in both retrospective and prospective studies. However, due to the complexity of ARDS patients and the limitations of current evidence, the actual impact of ECCO2R on patient outcome still remains to be defined. In this review, we discuss the main principles of ECCO2R and its clinical application in ARDS patients, in particular looking at clinical experiences of combined ECCO2R-CRRT treatments.

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a heterogeneous lung disease that is triggered by pulmonary and non-pulmonary pathol-ogies. It predominantly causes hypoxaemic respiratory failure and can lead to significant morbidity and mortality. Although ARDS re-mains underdiagnosed, 24% of mechanically ventilated patients in intensive care units and 33% of coronavirus disease (COVID-19) pa-tients admitted to the hospital are reported to have ARDS. Despite recent advances in treatment, mortality remains at more than 30% for all ARDS patients and 43% for severe ARDS. The pathophysiology is complex and involves acute pulmonary and systemic inflammation, alveolar oedema, and de-recruitment which lead to ventilation-perfusion mismatch, reduced lung compliance and hypoxaemia. Similarities in the pathophysiology of COVID-19 ARDS outnumber differences from non-COVID-19 ARDS. Inhomoge-neous distribution of transpulmonary pressure variation throughout the lungs in ARDS increases the risk of patient self-inflicted lung injury and ventilator-associated lung injury. Stratifying ARDS patients as per Berlin definition can help to recog-nize ARDS early, identify resource requirements and plan appropriate management. Treating the underlying cause, lung-protective ventila-tion and supportive care are the mainstays of clinical management. Multiple rescue therapies, novel treatments, and methods of facili-tating individualized ventilation have been described but many require further validation;and appropriate patient selection is warranted.

Spontaneous pneumomediastinum in Covid-19 : a case of complete resolution despite invasive positive pressure ventilation

We present the case of a 65-year-old patient who was admitted to the intensive care unit (ICU) due to Covid-19 respiratory failure. During his hospital stay, he developed a spontaneous pneumomediastinum (SP). To date, there have been few reports of SP associated with Covid-19 and even less is known about the impact of positive pressure ventilation on these patients. Our patient was first treated with high-flow nasal cannula oxygen therapy (HFNC). Because of further respiratory deterioration, he was supported with non-invasive ventilation (NIV). Later, he required intubation and ventilation with invasive positive pressure ventilation. Despite this, a complete spontaneous resolution of the pneumomediastinum was observed 13 days after the initial diagnosis. Copyright © Acta Anaesthesiologica Belgica, 2021.

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a heterogeneous lung disease that is triggered by pulmonary and non-pulmonary pathologies. It predominantly causes hypoxaemic respiratory failure and can lead to significant morbidity and mortality. Although ARDS remains underdiagnosed, 24% of mechanically ventilated patients in intensive care units and 33% of coronavirus disease (COVID-19) patients admitted to the hospital are reported to have ARDS. Despite recent advances in treatment, mortality remains at more than 30% for all ARDS patients and 43% for severe ARDS. The pathophysiology is complex and involves acute pulmonary and systemic inflammation, alveolar oedema, and de-recruitment which lead to ventilation-perfusion mismatch, reduced lung compliance and hypoxaemia. Similarities in the pathophysiology of COVID-19 ARDS outnumber differences from non-COVID-19 ARDS. Inhomogeneous distribution of transpulmonary pressure variation throughout the lungs in ARDS increases the risk of patient self-inflicted lung injury and ventilator-associated lung injury. Stratifying ARDS patients as per Berlin definition can help to recognize ARDS early, identify resource requirements and plan appropriate management. Treating the underlying cause, lung-protective ventilation and supportive care are the mainstays of clinical management. Multiple rescue therapies, novel treatments, and methods of facilitating individualized ventilation have been described but many require further validation;and appropriate patient selection is warranted.

Use of a novel "Split" ventilation system in bench and porcine modeling of acute respiratory distress syndrome.

Split ventilation (using a single ventilator to ventilate multiple patients) is technically feasible. However, connecting two patients with acute respiratory distress syndrome (ARDS) and differing lung mechanics to a single ventilator is concerning. This study aimed to: (1) determine functionality of a split ventilation system in benchtop tests, (2) determine whether standard ventilation would be superior to split ventilation in a porcine model of ARDS and (3) assess usability of a split ventilation system with minimal specific training. The functionality of a split ventilation system was assessed using test lungs. The usability of the system was assessed in simulated clinical scenarios. The feasibility of the system to provide modified lung protective ventilation was assessed in a porcine model of ARDS (n = 30). In bench testing a split ventilation system independently ventilated two test lungs under conditions of varying compliance and resistance. In usability tests, a high proportion of naïve operators could assemble and use the system. In the porcine model, modified lung protective ventilation was feasible with split ventilation and produced similar respiratory mechanics, gas exchange and biomarkers of lung injury when compared to standard ventilation. Split ventilation can provide some elements of lung protective ventilation and is feasible in bench testing and an in vivo model of ARDS.

Invasive mechanical ventilation in patients with acute respiratory distress syndrome receiving extracorporeal support: a narrative review of strategies to mitigate lung injury.

Veno-venous extracorporeal membrane oxygenation is indicated in patients with acute respiratory distress syndrome and severely impaired gas exchange despite evidence-based lung protective ventilation, prone positioning and other parts of the standard algorithm for treating such patients. Extracorporeal support can facilitate ultra-lung-protective ventilation, meaning even lower volumes and pressures than standard lung-protective ventilation, by directly removing carbon dioxide in patients needing injurious ventilator settings to maintain sufficient gas exchange. Injurious ventilation results in ventilator-induced lung injury, which is one of the main determinants of mortality in acute respiratory distress syndrome. Marked reductions in the intensity of ventilation to the lowest tolerable levels under extracorporeal support may be achieved and could thereby potentially mitigate ventilator-induced lung injury and theoretically patient self-inflicted lung injury in spontaneously breathing patients with high respiratory drive. However, the benefits of this strategy may be counterbalanced by the use of continuous deep sedation and even neuromuscular blocking drugs, which may impair physical rehabilitation and impact long-term outcomes. There are currently a lack of large-scale prospective data to inform optimal invasive ventilation practices and how to best apply a holistic approach to patients receiving veno-venous extracorporeal membrane oxygenation, while minimising ventilator-induced and patient self-inflicted lung injury. We aimed to review the literature relating to invasive ventilation strategies in patients with acute respiratory distress syndrome receiving extracorporeal support and discuss personalised ventilation approaches and the potential role of adjunctive therapies in facilitating lung protection.

Severe COVID-19 disease in a 2nd trimester pregnancy: Successful ECMO and mechanical ventilation management.

Extracorporeal membrane oxygenation (ECMO) is an invasive support strategy for cardiac, respiratory, or combined cardiorespiratory failure. ECMO has become increasing utilized in patients with severe respiratory failure due to COVID-19 infection. To our knowledge there is no report of successful ECMO utilization in second trimester of pregnancy leading to a successful outcome. We present a case of severe COVID-19 infection in a patient causing respiratory failure in the second trimester pregnancy. With diligent utilization of ECMO and mechanical ventilation we were able to support the patient's respiratory needs to allow her pregnancy to continue. Ultimately, the patient underwent successful caesarean section in the third trimester. This case highlights excellent lung injury protection and lung recovery can be achieved through optimal utilization of ECMO support together with a careful and closely monitored lung protective ventilation strategy, even while also supporting the patient through the increasing metabolic circumstances of a progressing pregnancy.

Managing Severe Hypoxic Respiratory Failure in COVID-19.

Purpose of Review: Adult respiratory distress syndrome is a life-threatening complication from severe COVID-19 infection resulting in severe hypoxic respiratory failure. Strategies at improving oxygenation have evolved over the course of the pandemic. Recent Findings: Although non-invasive respiratory support reduces the need for intubation, a significant number of patients with COVID-19 progress to invasive mechanical ventilation. Once intubated, a lung protective ventilation strategy should be employed that limits tidal volumes to 6 ml/kg of predicted body weight and employs sufficient positive end-expiratory pressure to maximize oxygen delivery while minimizing the fraction of inspired oxygen. Intermittent prone positioning is effective at improving survival, and there is a growing body of evidence that it can be safely performed in spontaneously breathing patients to reduce the need for invasive mechanical ventilation. Inhaled pulmonary vasodilators have not been shown to improve survival or cost-effectiveness in COVID-19 and should be used selectively. Summary: Finally, the best outcomes are likely achieved at centers with experience at severe ARDS management and protocols for escalation of care.

Complications of invasive mechanical ventilation in critically Ill Covid-19 patients - A narrative review.

Critically ill COVID-19 patients have to undergo positive pressure ventilation, a non-physiological and invasive intervention that can be lifesaving in severe ARDS. Similar to any other intervention, it has its pros and cons. Despite following Lung Protective Ventilation (LPV), some of the complications are frequently reported in these critically ill patients and significantly impact overall mortality. The complications related to invasive mechanical ventilation (IMV) in critically ill COVID-19 patients can be broadly divided into pulmonary and non-pulmonary. Among pulmonary complications, the most frequent is ventilator-associated pneumonia. Others are barotrauma, including subcutaneous emphysema, pneumomediastinum, pneumothorax, bullous lesions, cardiopulmonary effects of right ventricular dysfunction, and pulmonary complications mimicking cardiac failure, including pulmonary edema. Tracheal complications, including full-thickness tracheal lesions (FTTLs) and tracheoesophageal fistulas (TEFs) are serious but rare complications. Non-Pulmonary complications include neurological, nephrological, ocular, and oral complications.

The PANDORA Study: Prevalence and Outcome of Acute Hypoxemic Respiratory Failure in the Pre-COVID-19 Era.

OBJECTIVES: To establish the epidemiological characteristics, ventilator management, and outcomes in patients with acute hypoxemic respiratory failure (AHRF), with or without acute respiratory distress syndrome (ARDS), in the era of lung-protective mechanical ventilation (MV). DESIGN: A 6-month prospective, epidemiological, observational study. SETTING: A network of 22 multidisciplinary ICUs in Spain. PATIENTS: Consecutive mechanically ventilated patients with AHRF (defined as Pao2/Fio2 ≤ 300 mm Hg on positive end-expiratory pressure [PEEP] ≥ 5 cm H2O and Fio2 ≥ 0.3) and followed-up until hospital discharge. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Primary outcomes were prevalence of AHRF and ICU mortality. Secondary outcomes included prevalence of ARDS, ventilatory management, and use of adjunctive therapies. During the study period, 9,803 patients were admitted: 4,456 (45.5%) received MV, 1,271 (13%) met AHRF criteria (1,241 were included into the study: 333 [26.8%] met Berlin ARDS criteria and 908 [73.2%] did not). At baseline, tidal volume was 6.9 ± 1.1 mL/kg predicted body weight, PEEP 8.4 ± 3.1 cm H2O, Fio2 0.63 ± 0.22, and plateau pressure 21.5 ± 5.4 cm H2O. ARDS patients received higher Fio2 and PEEP than non-ARDS (0.75 ± 0.22 vs 0.59 ± 0.20 cm H2O and 10.3 ± 3.4 vs 7.7 ± 2.6 cm H2O, respectively [p < 0.0001]). Adjunctive therapies were rarely used in non-ARDS patients. Patients without ARDS had higher ventilator-free days than ARDS (12.2 ± 11.6 vs 9.3 ± 9.7 d; p < 0.001). All-cause ICU mortality was similar in AHRF with or without ARDS (34.8% [95% CI, 29.7-40.2] vs 35.5% [95% CI, 32.3-38.7]; p = 0.837). CONCLUSIONS: AHRF without ARDS is a very common syndrome in the ICU with a high mortality that requires specific studies into its epidemiology and ventilatory management. We found that the prevalence of ARDS was much lower than reported in recent observational studies.

Sex Differences in Use of Low Tidal Volume Ventilation in COVID-19-Insights From the PRoVENT-COVID Study.

The purpose of this study was to compare and understand differences in the use of low tidal volume ventilation (LTVV) between females and males with acute respiratory distress syndrome (ARDS) related to coronavirus disease 2019 (COVID-19). This is a post-hoc analysis of an observational study in invasively ventilated patients with ARDS related to COVID-19 in 22 ICUs in the Netherlands. The primary endpoint was the use of LTVV, defined as having received a median tidal volume (VT) ≤6 ml/kg predicted body weight (PBW) during controlled ventilation. A mediation analysis was used to investigate the impact of anthropometric factors, next to the impact of sex per se. The analysis included 934 patients, 251 females and 683 males. All the patients had ARDS, and there were no differences in ARDS severity between the sexes. On the first day of ventilation, females received ventilation with a higher median VT compared with males [6.8 (interquartile range (IQR) 6.0-7.6 vs. 6.3 (IQR 5.8-6.9) ml/kg PBW; p < 0.001]. Consequently, females received LTVV less often than males (23 vs. 34%; p = 0.003). The difference in the use of LTVV became smaller but persisted over the next days (27 vs. 36%; p = 0.046 at day 2 and 28 vs. 38%; p = 0.030 at day 3). The difference in the use LTVV was significantly mediated by sex per se [average direct effect of the female sex, 7.5% (95% CI, 1.7-13.3%); p = 0.011] and by differences in the body height [average causal mediation effect, -17.5% (-21.5 to -13.5%); p < 0.001], but not by the differences in actual body weight [average causal mediation effect, 0.2% (-0.8 to 1.2%); p = 0.715]. In conclusion, in this cohort of patients with ARDS related to COVID-19, females received LTVV less often than males in the first days of invasive ventilation. The difference in the use of LTVV was mainly driven by an anthropometric factor, namely, body height. Use of LTVV may improve by paying attention to correct titration of VT, which should be based on PBW, which is a function of body height.

Successful lung-protective ventilatory management during the VV-ECMO in a severe COVID-19 pneumonia patient with extensive pneumomediastinum and subcutaneous emphysema: a case report.

BACKGROUND: Ventilatory management of respiratory failure with pneumomediastinum/subcutaneous emphysema is not established. Herein, we report a case of severe COVID-19 pneumonia with extensive pneumomediastinum/subcutaneous emphysema, rescued by thorough lung-protective ventilatory management after applying the VV-ECMO. CASE PRESENTATION: A 68-year-old male with no medical history was admitted to a local hospital and diagnosed with COVID-19 pneumonia. His pulmonary parameters worsened during invasive ventilation due to the development of pneumomediastinum/subcutaneous emphysema, and then he was transferred to our hospital. On arrival, we immediately decided to apply VV-ECMO and switch to ultraprotective ventilation. After maintaining the initial ventilation with a neuromuscular blocking agent for 2 days, we gradually increased PEEP while limiting PIP to 25 cmH2O. The patient was weaned off VV-ECMO on day 10; he was transferred to the medical ward after extubation. CONCLUSIONS: Lung-protective ventilatory management should be performed thoroughly during VV-ECMO in severe COVID-19 pneumonia with pneumomediastinum/subcutaneous emphysema.

Evaluation of Aerosol Drug Delivery Options during Adult Mechanical Ventilation in the COVID-19 Era.

Drug delivery devices used for aerosol therapy during mechanical ventilation to ease the symptoms of respiratory diseases provide beneficial treatment but can also pose challenges. Reflecting the significant changes in global guidance around aerosol usage and lung-protective ventilation strategies, seen in response to the COVID-19 pandemic, for the first time, we describe the drug delivery performance of commonly used devices under these conditions. Here, vibrating mesh nebuliser (VMN), jet nebuliser (JN) and pressurised metered-dose inhaler (pMDI) performance was assessed during simulated adult mechanical ventilation. Both standard test breathing patterns and those representatives of low tidal volume (LTV) ventilation with concurrent active and passive humidification were investigated. Drug delivery using a VMN was significantly greater than that with a JN and pMDI for both standard and LTV ventilation. Humidification type did not affect the delivered dose across all device types for standard ventilation. Significant variability in the pMDI dosing was evident, depending on the timing of actuation and the adapter type used. pMDI actuation synchronised with inspiration resulted in a higher delivered drug dose. The type of adapter used for pMDI actuation influenced drug delivery, with the highest dose observed using the CombiHaler.

Toward Optimal Acute Respiratory Distress Syndrome Outcomes: Recognizing the Syndrome and Identifying Its Causes.

Acute respiratory distress syndrome is a common condition among critically ill patients, but remains under-recognized and undertreated. Under-recognition may result from confusion over the clinical inclusion criteria, as well as a misunderstanding of the complex relationship between the clinical syndrome, the variable histopathologic patterns, and the myriad clinical disorders that cause acute respiratory distress syndrome. The identification of the clinical syndrome and determination of the causal diagnosis are both required to optimize patient outcomes. Here we review the definition, discuss pitfalls in recognizing acute respiratory distress syndrome and consider an approach to ascertain specific etiologies of acute respiratory distress syndrome.

2020 Year in Review: Mechanical Ventilation During the First Year of the COVID-19 Pandemic.

Coronavirus disease 2019 (COVID-19) represents the greatest medical crisis encountered in the young history of critical care and respiratory care. During the early months of the pandemic, when little was known about the virus, the acute hypoxemic respiratory failure it caused did not appear to fit conveniently or consistently into our classification of ARDS. This not only re-ignited a half-century's long simmering debate over taxonomy, but also fueled similar debates over how PEEP and lung-protective ventilation should be titrated, as well as the appropriate role of noninvasive ventilation in ARDS. COVID-19 ignited other debates on emerging concepts such as ARDS phenotypes and patient self-inflicted lung injury from vigorous spontaneous breathing. Over a year later, these early perplexities have receded into the background without having been reviewed or resolved. With a full year of evidence having been published, this narrative review systematically analyzes whether COVID-19-associated respiratory failure is essentially ARDS, with perhaps a somewhat different course of presentation. This includes a review of the severity of hypoxemia and derangements in pulmonary mechanics, PEEP requirements, recruitment potential, ability to achieve lung-protective ventilation goals, duration of mechanical ventilation, associated mortality, and response to noninvasive ventilation. This paper also reviews the concepts of ARDS phenotypes and patient self-inflicted lung injury as these are crucial to understanding the contentious debate over the nature and management of COVID-19.