Year in review 2013: Critical Care - respirology

This review documents important progress made in 2013 in the field of critical care respirology, in particular with regard to acute respiratory failure and acute respiratory distress syndrome. Twenty-five original articles published in the respirology and critical care sections of Critical Care are discussed in the following categories: pre-clinical studies, protective lung ventilation – how low can we go, non-invasive ventilation for respiratory failure, diagnosis and prognosis in acute respiratory distress syndrome and respiratory failure, and promising interventions for acute respiratory distress syndrome.     

Year in review 2008: Critical Care - respirology

Original research contributions published in Critical Care in 2008 in the fields of respirology and critical care medicine are summarized. Eighteen articles were grouped into the following categories: acute lung injury and acute respiratory distress syndrome, mechanical ventilation, mechanisms of ventilator-induced lung injury, and tracheotomy decannulation and non-invasive ventilation.     

Year in review 2007: Critical Care – respirology

All original research contributions published in Critical Care in 2007 in the field of respirology and critical care medicine are summarized in this article. Fifteen papers were grouped in the following categories: acute lung injury and acute respiratory distress syndrome, mechanical ventilation, ventilator-induced lung injury, imaging, and other topics.     

Year in review 2007: Critical Care--respirology

All original research contributions published in Critical Care in 2007 in the field of respirology and critical care medicine are summarized in this article. Fifteen papers were grouped in the following categories: acute lung injury and acute respiratory distress syndrome, mechanical ventilation, ventilator-induced lung injury, imaging, and other topics.     

Year in review in Critical Care, 2003 and 2004: respirology and critical care

We summarize all original research in the field of respirology and critical care published in 2003 and 2004 in Critical Care. Articles were grouped into the following categories to facilitate a rapid overview: pathophysiology, therapeutic approaches, and outcome in acute lung injury and acute respiratory distress syndrome; hypoxic pulmonary arterial hypertension; mechanical ventilation; liberation from mechanical ventilation and tracheostomy; ventilator-associated pneumonia; multidrug-resistant infections; pleural effusion; sedation and analgesia; asthma; and techniques and monitoring.     

Year in review 2011: Critical Care - Out-of-hospital cardiac arrest and trauma

Management of acute respiratory failure is an important component of intensive care. In this review, we analyze 21 original research articles published last year in Critical Care in the field of respiratory and critical care medicine. The articles are summarized according to the following topic categories: acute respiratory distress syndrome, mechanical ventilation, adjunctive therapies, and pneumonia.     

Year in review 2011: Critical Care - respirology

Management of acute respiratory failure is an important component of intensive care. In this review, we analyze 21 original research articles published last year in Critical Care in the field of respiratory and critical care medicine. The articles are summarized according to the following topic categories: acute respiratory distress syndrome, mechanical ventilation, adjunctive therapies, and pneumonia.     

Noninvasive ventilation in acute respiratory failure

BACKGROUND: Noninvasive ventilation has assumed an important role in the management of respiratory failure in critical care units, but it must be used selectively depending on the patient's diagnosis and clinical characteristics. DATA: We review the strong evidence supporting the use of noninvasive ventilation for acute respiratory failure to prevent intubation in patients with chronic obstructive pulmonary disease exacerbations or acute cardiogenic pulmonary edema, and in immunocompromised patients, as well as to facilitate extubation in patients with chronic obstructive pulmonary disease who require initial intubation. Weaker evidence supports consideration of noninvasive ventilation for chronic obstructive pulmonary disease patients with postoperative or postextubation respiratory failure; patients with acute respiratory failure due to asthma exacerbations, pneumonia, acute lung injury, or acute respiratory distress syndrome; during bronchoscopy; or as a means of preoxygenation before intubation in critically ill patients with severe hypoxemia. CONCLUSION: Noninvasive ventilation has assumed an important role in managing patients with acute respiratory failure. Patients should be monitored closely for signs of noninvasive ventilation failure and promptly intubated before a crisis develops. The application of noninvasive ventilation by a trained and experienced intensive care unit team, with careful patient selection, should optimize patient outcomes.     

Acute respiratory distress syndrome: diagnosis and management

Acute respiratory distress syndrome manifests as rapidly progressive dyspnea, tachypnea, and hypoxemia. Diagnostic criteria include acute onset, profound hypoxemia, bilateral pulmonary infiltrates, and the absence of left atrial hypertension. Acute respiratory distress syndrome is believed to occur when a pulmonary or extrapulmonary insult causes the release of inflammatory mediators, promoting neutrophil accumulation in the microcirculation of the lung. Neutrophils damage the vascular endothelium and alveolar epithelium, leading to pulmonary edema, hyaline membrane formation, decreased lung compliance, and difficult air exchange. Most cases of acute respiratory distress syndrome are associated with pneumonia or sepsis. It is estimated that 7.1 percent of all patients admitted to an intensive care unit and 16.1 percent of all patients on mechanical ventilation develop acute lung injury or acute respiratory distress syndrome. In-hospital mortality related to these conditions is between 34 and 55 percent, and most deaths are due to multiorgan failure. Acute respiratory distress syndrome often has to be differentiated from congestive heart failure, which usually has signs of fluid overload, and from pneumonia. Treatment of acute respiratory distress syndrome is supportive and includes mechanical ventilation, prophylaxis for stress ulcers and venous thromboembolism, nutritional support, and treatment of the underlying injury. Low tidal volume, high positive end-expiratory pressure, and conservative fluid therapy may improve outcomes. A spontaneous breathing trial is indicated as the patient improves and the underlying illness resolves. Patients who survive acute respiratory distress syndrome are at risk of diminished functional capacity, mental illness, and decreased quality of life; ongoing care by a primary care physician is beneficial for these patients.     

The number of failing organs predicts non-invasive ventilation failure in children with ALI/ARDS

Purpose  

Non-invasive positive pressure ventilation (NIV) is being increasingly used in paediatric critical care, although its use in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is still debated. No definite data are available for the prediction of NIV outcome in such selected populations. We aimed to identify which factors might affect NIV failure in paediatric ALI/ARDS patients.     

Severe febrile respiratory illnesses as a cause of mass critical care

Febrile respiratory illnesses with respiratory failure are one of the most common reasons for admission to the intensive care unit. Most causes of febrile respiratory illness are bacterial and viral agents of community-acquired pneumonia. However, a small number of rare and highly contagious agents can initially present as febrile respiratory illnesses, which can lead to an epidemic that can greatly impact the health care system. This impact includes sustained mass critical care, with potential scarcity of critical resources (eg, positive-pressure ventilators), spread of disease to health care workers, sustained spread within the community, and extensive morbidity and mortality. The main agents of febrile respiratory illness that would lead to an epidemic include influenza, the coronavirus that causes severe acute respiratory syndrome, smallpox, viral hemorrhagic fever, plague, tularemia, and anthrax. Recognition of these agents occurs largely based on epidemiological clues, and management consists of antibiotics, antivirals, supportive care, and positive-pressure ventilation. Acute respiratory failure and acute respiratory distress syndrome occur with these agents, so a lung-protective (low tidal volume) ventilation strategy is indicated. Additional respiratory care measures, such as nebulized medications, bronchoscopy, humidified oxygen, and airway suctioning, potentiate aerosolization of the virus or bacteria and increase the risk of transmission to health care workers and patients. Thus, appropriate personal protective equipment, including an N95 mask or powered air-purifying respirator, is indicated. A basic understanding of the epidemiology, clinical findings, diagnosis, and treatment of these agents will provide a foundation for early isolation, evaluation, infection control, and public health involvement and response in cases of a febrile respiratory illness that causes respiratory failure.     

Year in review 2012: Critical Care - respirology

Acute respiratory failure is a dominant feature of critical illness. In this review, we discuss 17 studies published last year in Critical Care. The discussion focuses on articles on several topics: respiratory monitoring, acute respiratory distress syndrome, noninvasive ventilation, airway management, secretion management and weaning.     

Percutaneous dilation tracheostomy during high-frequency oscillatory ventilation

OBJECTIVE: To ascertain the feasibility and the safety of percutaneous dilational tracheostomy in patients with acute respiratory distress syndrome receiving high-frequency oscillatory ventilation. DESIGN: Case series. SETTING: Tertiary adult intensive care unit in a university teaching hospital. PATIENTS: Five patients with acute respiratory distress syndrome. INTERVENTIONS: Percutaneous dilational tracheostomy during high-frequency oscillatory ventilation. MEASUREMENTS AND MAIN RESULTS: Percutaneous dilational tracheostomy was safely performed on all five patients. Hemodynamic and respiratory variables remained stable during the procedure. No complications were attributable to either the percutaneous dilational tracheostomy or high-frequency oscillatory ventilation. CONCLUSIONS: Percutaneous dilational tracheostomy can be safely performed on patients with acute respiratory distress syndrome during high-frequency oscillatory ventilation.     

Low stretch ventilation strategy in acute respiratory distress syndrome: eight years of clinical experience in a single center

CONTEXT: In recent years, protective ventilation with airway pressure limitation has constituted a major advance in acute respiratory distress syndrome treatment and has led to a substantial improvement in prognosis. With this therapeutic rationale, one may even question nowadays whether the severity of respiratory failure still influences mortality. OBJECTIVE: To determine whether the severity of respiratory failure, scored according to the usual criteria, still influences mortality in acute respiratory distress syndrome patients when a low stretch ventilation was used and to assess the impact on mortality of other nonpulmonary organ dysfunction, particularly circulatory failure. DESIGN AND SETTING: A retrospective study conducted in the medical intensive care unit of a French university hospital from October 1993 to December 2001. PATIENTS A total of 150 acute respiratory distress syndrome patients who were administered uniform protective ventilation with a limited plateau pressure (<30 cm H2O), a low positive end-expiratory pressure (<10 cm H2O), and the same strategy concerning hemodynamic support and dialysis when required. MAIN OUTCOME AND MEASURES: Mean age, general severity index (Simplified Acute Physiologic Score II), number of associated organ failures (Logistic Organ Dysfunction Score), respiratory severity indices (Pao2/Fio2, Lung Injury Severity Score), and severity of initial circulatory failure (circulatory failure present at admission or that developed during the first 48 hrs) were compared, according to recovery or death, and evaluated by a logistic regression model, which allows simultaneous control of multiple factors. RESULTS: The average mortality rate for the whole group was 38%, with 93 patients recovering after an average duration of mechanical ventilation of 18 +/- 13 days. The major factor significantly and independently associated with probability of dying was the severity of circulatory failure (p =.0001, odds ratio = 10.17). Patients free from initial circulatory failure (39 patients) had a 95% recovery rate. CONCLUSION: With our low stretch strategy, the severity of circulatory failure was the main determinant of acute respiratory distress syndrome prognosis. Patients with isolated respiratory failure during the first 48 hrs of respiratory support have an excellent chance of recovery when treated with protective ventilation associated with a low positive end-expiratory pressure.     

Initial emergency department mechanical ventilation strategies for COVID-19 hypoxemic respiratory failure and ARDS

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging viral pathogen that causes the novel coronavirus disease of 2019 (COVID-19) and may result in hypoxemic respiratory failure necessitating invasive mechanical ventilation in the most severe cases.ObjectiveThis narrative review provides evidence-based recommendations for the treatment of COVID-19 related respiratory failure requiring invasive mechanical ventilation.DiscussionIn severe cases, COVID-19 leads to hypoxemic respiratory failure that may meet criteria for acute respiratory distress syndrome (ARDS). The mainstay of treatment for ARDS includes a lung protective ventilation strategy with low tidal volumes (4–8 mL/kg predicted body weight), adequate positive end-expiratory pressure (PEEP), and maintaining a plateau pressure of < 30 cm H₂O. While further COVID-19 specific studies are needed, current management should focus on supportive care, preventing further lung injury from mechanical ventilation, and treating the underlying cause.ConclusionsThis review provides evidence-based recommendations for the treatment of COVID-19 related respiratory failure requiring invasive mechanical ventilation.     

Ventilator strategies for posttraumatic acute respiratory distress syndrome: airway pressure release ventilation and the role of spontaneous breathing in critically ill patients

PURPOSE OF REVIEW: Patients who experience severe trauma are at increased risk for the development of acute lung injury and acute respiratory distress syndrome. The management strategies used to treat respiratory failure in this patient population should be comprehensive. Current trends in the management of acute lung injury and acute respiratory distress syndrome consist of maintaining acceptable gas exchange while limiting ventilator-associated lung injury. RECENT FINDINGS: Currently, two distinct forms of ventilator-associated lung injury are recognized to produce alveolar stress failure and have been termed low-volume lung injury (intratidal alveolar recruitment and derecruitment) and high-volume lung injury (alveolar stretch and overdistension). Pathologically, alveolar stress failure from low- and high-volume ventilation can produce lung injury in animal models and is termed ventilator-induced lung injury. The management goal in acute lung injury and acute respiratory distress syndrome challenges clinicians to achieve the optimal balance that both limits the forms of alveolar stress failure and maintains effective gas exchange. The integration of new ventilator modes that include the augmentation of spontaneous breathing during mechanical ventilation may be beneficial and may improve the ability to attain these goals. SUMMARY: Airway pressure release ventilation is a mode of mechanical ventilation that maintains lung volume to limit intra tidal recruitment /derecruitment and improves gas exchange while limiting over distension. Clinical and experimental data demonstrate improvements in arterial oxygenation, ventilation-perfusion matching (less shunt and dead space ventilation), cardiac output, oxygen delivery, and lower airway pressures during airway pressure release ventilation. Mechanical ventilation with airway pressure release ventilation permits spontaneous breathing throughout the entire respiratory cycle, improves patient comfort, reduces the use of sedation, and may reduce ventilator days.     

Respiratory controversies in the critical care setting. Does high-frequency ventilation offer benefits over conventional ventilation in adult patients with acute respiratory distress syndrome?

High-frequency ventilation is the application of mechanical ventilation with a respiratory rate > 100 breaths/min. High-frequency oscillatory ventilation (HFOV) is the form of high-frequency ventilation most widely used in adult critical care. The principles of lung-protective ventilation have matured in parallel with the technology for HFOV. The 2 basic principles of lung-protective ventilation are the use of small tidal volume and maintenance of adequate alveolar recruitment. Research in animal models and humans demonstrate that HFOV can support gas exchange with much smaller tidal volume than can be achieved with conventional ventilation. HFOV also provides more effective lung recruitment than conventional mechanical ventilation. However, at present, evidence is lacking that survival in adults with acute respiratory distress syndrome is improved by HFOV. Although HFOV may improve P(aO(2)) in some patients, this improvement is often transitory. Available evidence does not support that pulmonary inflammation is reduced with HFOV in adult acute respiratory distress syndrome. Heavy sedation and often paralysis are necessary. The promise of HFOV as a lung-protective ventilation strategy remains attractive, but additional clinical trials are needed to determine whether this approach is superior to lung-protective ventilation with conventional mechanical ventilation.     

Noninvasive ventilation in patients with hypoxemic acute respiratory failure

PURPOSE OF REVIEW: To discuss the recent literature concerning the use of noninvasive ventilation for hypoxemic acute respiratory failure. RECENT FINDINGS: The benefits of noninvasive ventilation for patients with hypoxemic acute respiratory failure are unclear. In immunocompromised patients and following thoracic surgery, there is a strong rationale for using noninvasive ventilation to treat acute respiratory failure. Prophylactic continuous positive airway pressure after abdominal or thoracic surgery and prophylactic noninvasive ventilation in patients at risk of extubation failure have proved beneficial. Recent studies show that noninvasive ventilation has a favourable impact in immunocompetent patients with acute lung injury/acute respiratory distress syndrome, but caution is required. In hypoxemic acute respiratory failure after extubation, one study reported excess mortality in patients treated with noninvasive ventilation, possibly related to the delay for intubation. A major issue is avoiding undue noninvasive ventilation prolongation and staying alert for predictors of early noninvasive ventilation failure. Caution, close monitoring, and broad experience are required. SUMMARY: Hypoxemic acute respiratory failure may benefit from noninvasive ventilation or continuous positive airway pressure, but undue prolongation should be avoided. In postextubation respiratory failure there is no evidence for routine use of noninvasive ventilation.     

Pharmacotherapy of acute lung injury and the acute respiratory distress syndrome

Acute lung injury and the acute respiratory distress syndrome are common syndromes with a high mortality rate that affect both medical and surgical patients. Better understanding of the pathophysiology of acute lung injury and the acute respiratory distress syndrome and advances in supportive care and mechanical ventilation have led to improved clinical outcomes since the syndrome was first described in 1967. Although several promising pharmacological therapies, including surfactant, nitric oxide, glucocorticoids and lysofylline, have been studied in patients with acute lung injury and the acute respiratory distress syndrome, none of these pharmacological treatments reduced mortality. This article provides an overview of pharmacological therapies of acute lung injury and the acute respiratory distress syndrome tested in clinical trials and current recommendations for their use as well as a discussion of potential future pharmacological therapies including beta(2)-adrenergic agonist therapy, keratinocyte growth factor, and activated protein C.     

Prone positioning: is it safe and effective?

Prone positioning has been used as a treatment option for patients with acute lung injury or acute respiratory distress syndrome (ARDS) since the early 1970s. Prone position and extended prone position ventilation have been shown to increase end-expiratory lung volume, alveolar recruitment, and oxygenation in patients with severe hypoxemic and acute respiratory failure. Prone positioning is not a benign procedure, and there are potential risks (complications) that can occur to both the patient and the health care worker. Notable complications that can arise include: unplanned extubation, lines pulled, tubes kinked, and back and other injuries to personnel. Prone positioning is a viable, inexpensive therapy for the treatment of severe ARDS. This maneuver consistently improves systemic oxygenation in 70% to 80% of patients with ARDS. With the utilization of a standardized protocol and a trained and dedicated critical care staff, prone positioning can be performed safely.