The Reign of the Ventilator: Acute Respiratory Distress Syndrome, COVID-19, and Technological Imperatives in Intensive Care.

In the early phase of the COVID-19 pandemic, a dispute arose as to whether the disease caused a typical or atypical version of acute respiratory distress syndrome (ARDS). This essay recounts the emergence of ARDS and places it in the context of the technological transformation of modern hospital care-particularly the emergence of intensive care after the 1952 Copenhagen polio epidemic. The polio epidemic seemed to show the value of manual positive-pressure ventilation, leading to the proliferation of mechanical ventilators and the expansion of intensive care units in the 1960s. This created the conditions of possibility for ARDS to be described and institutionalized within modern intensive care. Yet the centrality of the ventilator to descriptions and definitions of ARDS quickly made it difficult to conceive of the disorder outside the framework of mechanical ventilation and blood gas levels, or to acknowledge the degree to which the ventilator was a source of iatrogenic injury and complications. Moreover, the imperative to understand and treat ARDS with mechanical ventilation set the stage for the early confusion about whether patients with COVID-19 should receive mechanical ventilation. This history offers many crucial lessons about how new technologies can lead to new and valuable therapies but can also subtly shape and constrain medical thinking. Moreover, ventilators not only changed how respiratory disorders were conceived; they also brought new forms of respiratory illness into existence.

Acute respiratory distress syndrome. Half a century of its description / Síndrome de distrés respiratorio agudo. A medio siglo de su descripción

It has been 50 years since the first description of the respiratory distress syndrome or acute respiratory distress syndrome (ARDS), advances from the physiopathological view are immense, unfortunately, the case fatality rate has had little variation, it is important to disseminate the knowledge to achieve the proper diagnosis and treatment.

Han pasado 50 años desde la descripción original del síndrome de distrés respiratorio o síndrome de dificultad respiratoria aguda (SDRA), los avances desde el punto de vista fisiopatológico son inmensos, desgraciadamente la letalidad ha tenido poca variación, por ello sigue siendo importante difundir el conocimiento requerido para lograr el diagnóstico y tratamiento adecuados.

At 50 years of the description of acute respiratory distress syndrome. / A 50 años de la descripción del síndrome de insuficiencia respiratoria aguda.

In 1967, Ashbaugh et al. published in the Lancet the description of a new entity, for which they coined the name "adult respiratory distress syndrome". On that article, they thoroughly described 12 patients who had respiratory distress with bilateral pulmonary infiltrates and oxygen therapy-refractory hypoxemia. For its management, emphasis was made on the importance of intubation and mechanical ventilation with positive end-expiratory pressure. At 50 years of its first publication, great advances on the knowledge of this condition have been achieved, which has influenced on patient management and survival. To celebrate this 50th anniversary, the National Academy of Medicine of Mexico organized a symposium with the purpose to spread the knowledge about this condition, recognize the researchers who made the original description and those who over the course of 50 years of history have contributed to its better understanding. The symposium addressed the topics of lung-kidney interaction, molecular bases of the disease and therapeutic advances.

En 1967, Ashbaugh et al. publicaron en Lancet la descripción de una nueva entidad para la que acuñaron el nombre "síndrome de distress respiratorio del adulto". En ese artículo describieron minuciosamente a 12 enfermos que presentaban insuficiencia respiratoria, con infiltración pulmonar bilateral e hipoxemia resistente a oxigenoterapia. Para su manejo se hizo énfasis en la importancia de la intubación y la ventilación mecánica con presión positiva al final de la espiración. A 50 años de la publicación se han logrado grandes avances en el conocimiento de esta enfermedad, lo que ha influido en el manejo y supervivencia de los pacientes. Para celebrar este cincuentenario, la Academia Nacional de Medicina de México organizó un simposio que tuvo como objetivos difundir el conocimiento de esta enfermedad, reconocer a los personajes que hicieron la descripción original y a quienes en 50 años de historia han contribuido a su mejor entendimiento. El simposio abordó los temas de interacción pulmón-riñón, bases moleculares de la enfermedad y avances en el tratamiento.

Fifty Years of Research in ARDS. Is Extracorporeal Circulation the Future of Acute Respiratory Distress Syndrome Management?

Mechanical ventilation (MV) remains the cornerstone of acute respiratory distress syndrome (ARDS) management. It guarantees sufficient alveolar ventilation, high FiO2 concentration, and high positive end-expiratory pressure levels. However, experimental and clinical studies have accumulated, demonstrating that MV also contributes to the high mortality observed in patients with ARDS by creating ventilator-induced lung injury. Under these circumstances, extracorporeal lung support (ECLS) may be beneficial in two distinct clinical settings: to rescue patients from the high risk for death associated with severe hypoxemia, hypercapnia, or both not responding to maximized conventional MV, and to replace MV and minimize/abolish the harmful effects of ventilator-induced lung injury. High extracorporeal blood flow venovenous extracorporeal membrane oxygenation (ECMO) may therefore rescue the sickest patients with ARDS from the high risk for death associated with severe hypoxemia, hypercapnia, or both not responding to maximized conventional MV. Successful venovenous ECMO treatment in patients with extremely severe H1N1-associated ARDS and positive results of the CESAR trial have led to an exponential use of the technology in recent years. Alternatively, lower-flow extracorporeal CO2 removal devices may be used to reduce the intensity of MV (by reducing Vt from 6 to 3-4 ml/kg) and to minimize or even abolish the harmful effects of ventilator-induced lung injury if used as an alternative to conventional MV in nonintubated, nonsedated, and spontaneously breathing patients. Although conceptually very attractive, the use of ECLS in patients with ARDS remains controversial, and high-quality research is needed to further advance our knowledge in the field.

Fifty Years of Research in ARDS. Gas Exchange in Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) is characterized by severe impairment of gas exchange. Hypoxemia is mainly due to intrapulmonary shunt, whereas increased alveolar dead space explains the alteration of CO2 clearance. Assessment of the severity of gas exchange impairment is a requisite for the characterization of the syndrome and the evaluation of its severity. Confounding factors linked to hemodynamic status can greatly influence the relationship between the severity of lung injury and the degree of hypoxemia and/or the effects of ventilator settings on gas exchange. Apart from situations of rescue treatment, targeting optimal gas exchange in ARDS has become less of a priority compared with prevention of injury. A complex question for clinicians is to understand when improvement in oxygenation and alveolar ventilation is related to a lower degree or risk of injury for the lungs. In this regard, a full understanding of gas exchange mechanism in ARDS is imperative for individualized symptomatic support of patients with ARDS.

History of Mechanical Ventilation. From Vesalius to Ventilator-induced Lung Injury.

Mechanical ventilation is a life-saving therapy that catalyzed the development of modern intensive care units. The origins of modern mechanical ventilation can be traced back about five centuries to the seminal work of Andreas Vesalius. This article is a short history of mechanical ventilation, tracing its origins over the centuries to the present day. One of the great advances in ventilatory support over the past few decades has been the development of lung-protective ventilatory strategies, based on our understanding of the iatrogenic consequences of mechanical ventilation such as ventilator-induced lung injury. These strategies have markedly improved clinical outcomes in patients with respiratory failure.

Thomas L Petty's lessons for the respiratory care clinician of today.

Because of the importance of his original contributions and their practical relevance today, Thomas L Petty (1932-2009) was arguably the most important physician in the history of respiratory care. As much as any single individual, he was responsible for the concept of intensive and multidisciplinary respiratory care. In the 1960s and 1970s, he made key observations and introduced pioneering therapies in the ICU and in the home. He was the first to describe and name ARDS and to show how to use PEEP to treat life-threatening hypoxemia. He was one of the first anywhere to organize a pulmonary rehabilitation program and to show the beneficial effects of long-term oxygen therapy in COPD. Dr Petty emphasized the importance of practical, hands-on respiratory care education for both physicians and non-physicians using a collaborative team approach. He targeted educational activities and practical resources specifically to patients, and he showed how researchers and clinicians could interact responsibly with innovators in industry to the benefit of both. His life and career provide 6 important lessons for respiratory clinicians today and in the future: (1) whatever their roles, RTs and other clinicians in this field need to be experts in its core areas, such as mechanical ventilation, ARDS, and COPD; (2) respiratory care is a team activity: every member is important, and all the members need to communicate well and work together; (3) education needs to be targeted to those in the best position to benefit the patient, including primary care providers and family members; (4) everyone in the field needs to understand the important role of the respiratory care industry and to deal with it responsibly; (5) it must never be forgotten that it is all about the patient; and (6) respiratory care should be exciting and fun.

Were equatorial regions less affected by the 2009 influenza pandemic? The Brazilian experience.

Although it is in the Tropics where nearly half of the world population lives and infectious disease burden is highest, little is known about the impact of influenza pandemics in this area. We investigated the mortality impact of the 2009 influenza pandemic relative to mortality rates from various outcomes in pre-pandemic years throughout a wide range of latitudes encompassing the entire tropical, and part of the subtropical, zone of the Southern Hemisphere (+5(°)N to -35(°)S) by focusing on a country with relatively uniform health care, disease surveillance, immunization and mitigation policies: Brazil. To this end, we analyzed laboratory-confirmed deaths and vital statistics mortality beyond pre-pandemic levels for each Brazilian state. Pneumonia, influenza and respiratory mortality were significantly higher during the pandemic, affecting predominantly adults aged 25 to 65 years. Overall, there were 2,273 and 2,787 additional P&I- and respiratory deaths during the pandemic, corresponding to a 5.2% and 2.7% increase, respectively, over average pre-pandemic annual mortality. However, there was a marked spatial structure in mortality that was independent of socio-demographic indicators and inversely related with income: mortality was progressively lower towards equatorial regions, where low or no difference from pre-pandemic mortality levels was identified. Additionally, the onset of pandemic-associated mortality was progressively delayed in equatorial states. Unexpectedly, there was no additional mortality from circulatory causes. Comparing disease burden reliably across regions is critical in those areas marked by competing health priorities and limited resources. Our results suggest, however, that tropical regions of the Southern Hemisphere may have been disproportionally less affected by the pandemic, and that climate may have played a key role in this regard. These findings have a direct bearing on global estimates of pandemic burden and the assessment of the role of immunological, socioeconomic and environmental drivers of the transmissibility and severity of this pandemic.

History of technology in the intensive care unit.

Critical care medicine is a young specialty and since its inception has been heavily reliant upon technology. Invasive monitoring has its humble beginnings in the continuous monitoring of heart rate and rhythm. From the development of right heart catheterization to the adaption of the echocardiogram for use in shock, intensivists have used technology to monitor hemodynamics. The care of the critically ill has been buoyed by investigators who sought to offer renal replacement therapy to unstable patients and worked to improve the monitoring of oxygen saturation. The evolution of mechanical ventilation for the critically ill embodies innumerable technological advances. More recently, critical care has insisted upon rigorous testing and cost-benefit analysis of technological advances.

Theoretically estimated risk of severe acute respiratory syndrome transmission through blood transfusion during an epidemic in Shenzhen, Guangdong, China in 2003.

BACKGROUND: Severe acute respiratory syndrome (SARS) is a newly recognized infectious disease that caused an outbreak in south China in 2003. The cause of SARS was identified as a novel coronavirus (CoV). The existence of asymptomatic seroconvertors and the detection of the SARS-CoV RNA in plasma during the course of infection all suggest that SARS could, as least theoretically, be transmitted by transfusion. An estimate of the risk of SARS transmission through blood transfusion will contribute to decisions concerning blood safety monitoring and may be useful in the design of strategies to decrease the risk of transfusion-transmitted infections. STUDY DESIGN AND METHODS: Case onset dates from the 2003 Shenzhen SARS epidemic and investigational results from Taiwan on viremia in humans are used to estimate the number of cases that were viremic throughout the epidemic. Estimates of the asymptomatic-to-clinically confirmed SARS-CoV infection ratio, the proportion of asymptomatic infections reported in a seroprevalence survey in Hongkong, and the population size of Shenzhen are used to infer the SARS-CoV transfusion-transmission risk. Statistical resampling methods are used. RESULTS: Based on data from Shenzhen, Hongkong and Taiwan, the maximum and mean risk (per million) of SARS-CoV transmission from donors in Shenzhen were estimated as 23.57 (95% CI: 6.83-47.69) and 14.11 (95% CI: 11.00-17.22), respectively. The estimated risk peaked on April 02, 2003. CONCLUSIONS: Although there are currently no confirmed reports of the transmission of SARS-CoV from asymptomatic individuals, recent research data indicate that transfusion-transmitted SARS-CoV is at least theoretically possible. Although the risk is low, with its rapid spread of the disease, appearance of alarmingly high infectivity and high fatality rate, public health authorities need to consider strategies for blood donor recruitment and virus inactivation during an epidemic to further ensure blood safety.