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.

A technical review of the history, development and performance of the anaesthetic conserving device "AnaConDa" for delivering volatile anaesthetic in intensive and post-operative critical care.

There is a shift in critical care to adopt volatile anaesthetics as sedatives for certain patients using mechanical ventilation. Accompanying this shift is a growing body of literature describing the advantages or disadvantages of using isoflurane or sevoflurane for long term sedation. This practise requires a cost effective, efficient and safe means to deliver these drugs that can simultaneously operate with modern critical care ventilators and ventilation protocols while protecting the care environment and care workers from excessive exposure to the drugs. The anaesthetic conserving device ("AnaConDa", Sedana Medical) is one device that delivers a safe sedative dose of either isoflurane or sevoflurane to a patient using existing critical care ventilators, common syringe pumps and gas monitors. The device is essentially a small disposable anaesthetic vaporizer and HME filter combined into one airway component. Similar to an HME filter, the device reflects moisture back to the patient, but also reflects 90% of the anaesthetic by adsorbing and releasing the drug using a proprietary carbon filament reflecting medium. This reflection reduces the total amount of anaesthetic needed, reducing that which is exhausted or scavenged upon exhalation. It can be used for 24 h of sedation, and fits into current critical care ventilator circuits almost without modifications. This article will describe the physical characteristics of the device, how it works, its development history and the performance parameters under which it can be used.

The mechanical ventilator: past, present, and future.

The use of ventilatory assistance can be traced back to biblical times. However, mechanical ventilators, in the form of negative-pressure ventilation, first appeared in the early 1800s. Positive-pressure devices started to become available around 1900 and today's typical intensive care unit (ICU) ventilator did not begin to be developed until the 1940s. From the original 1940s ventilators until today, 4 distinct generations of ICU ventilators have existed, each with features different from that of the previous generation. All of the advancements in ICU ventilator design over these generations provide the basis for speculation on the future. ICU ventilators of the future will be able to integrate electronically with other bedside technology; they will be able to effectively ventilate all patients in all settings, invasively and noninvasively; ventilator management protocols will be incorporated into the basic operation of the ventilator; organized information will be presented instead of rows of unrelated data; alarm systems will be smart; closed-loop control will be present on most aspects of ventilatory support; and decision support will be available. The key term that will be used to identify these future ventilators will be smart!

Hyaline membrane and neonatal radiology--Ian Donald's first venture into imaging research.

While he was working at the Royal Postgraduate Medical School, Ian Donald (later Regius Professor of Midwifery, University of Glasgow and a pioneer of diagnostic ultrasound) collaborated with Albert Claireaux and Robert Steiner on histological and radiological studies of hyaline membrane disease. In 1953, Donald and Steiner published thefirst radiological study of a series of cases. The success of this research stimulated Donald's interest in imaging technologies.

A practical mechanical respirator, 1929: the "iron lung".

No satisfactory mechanical respirator existed before 1929, when Philip Drinker and Louis Shaw described an apparatus of their own design. This machine was in the form of a cylindrical tank enclosing the patient's body and chest, leaving the head outside the chamber under atmospheric pressure. Air pumps, later a bellows, raised and lowered pressure within the tank to assume the entire work of breathing. Popularly named the iron lung, the Drinker respirator supported thousands of patients afflicted with respiratory paralysis during the polio era. It was being superseded by positive-pressure airway ventilators just as the polio era came to a close. Today the Drinker respirator has disappeared virtually without a trace. Although its disadvantage was its cumbersome size, we must concede that it supported patients over the long term with fewer complications than do the respirators of today.

The modern evolution of mechanical ventilation.

Continuous mechanical ventilation used for life support is accepted as standard practice in nearly every hospital in the United States today. The history of the evolution of techniques that we take virtually for granted today is fascinating. This article recounts some of the highlights in the development of modern-day mechanical ventilators, with emphasis on the past 25 years.

A historical perspective on the use of noninvasive ventilatory support alternatives.

This article traces the development of mechanical ventilatory support methods from the use of body ventilators to tracheal cannulation to the use of noninvasive ventilatory support and airway secretion management alternatives. Although it has been known that tracheostomy tubes could be used for ventilatory support and airway secretion management since 1869, body ventilators continued to be the main methods of long-term ventilatory support in the United States, with tracheostomy performed only for patients with severe bulbar muscle dysfunction, until the late 1950s. Recent technological developments, however, have created renewed interest in noninvasive alternatives.

Ventilation and ventilators.

The history of ventilation is reviewed briefly and recent developments in techniques of ventilation are discussed. Operating features of ventilators have changed in the past few years, partly as the result of clinical progress; yet, technology appears to have outstripped the clinician's ability to harness it most effectively. Clinical discipline and training of medical staff in the use of ventilators could be improved. The future is promising if clinician and designer can work together closely. Ergonomics of ventilators and their controls and the provision of alarms need special attention. Microprocessors are likely to feature prominently in the next generation of designs.

Scotland's first iron lung.

The history of artificial ventilation and the development of the iron lung in the USA by Drinker and his colleagues is discussed. The building and use of an iron lung by Dr R G Henderson in Aberdeen in 1933 is described. The development of other types of ventilator in the UK is recorded and the circumstances whereby positive pressure ventilation was introduced in Denmark in 1952 is outlined.

Historical perspectives on the development and use of mechanical ventilation.

Contemporary advancements in cardiothoracic and abdominal surgical procedures have been historically dependent on the development and adoption of controlled airway management, specifically endotracheal intubation, controlled positive-pressure ventilation, and the use of automatic positive-pressure mechanical ventilators. More than 400 years elapsed before the 16th Century theories of Paracelsus and the demonstrations of Vesalius were routinely adopted to solve the "pneumothorax problem" that prevented complicated or prolonged surgical procedures within the pleural cavity. Acceptance and implementation of controlled positive-pressure ventilation was impeded for decades by the inability to maintain and protect the airway. Consequently, emphasis on the development of mechanical ventilation was directed toward machinery that provided safer negative-pressure respiratory support. The introduction of curare into European anesthesia practice and the adoption of protective airway practices during the poliomyelitis epidemics led to routine use of controlled positive-pressure ventilation and construction of dependable machinery. Laboratory investigations, exploring complications from cardiothoracic surgery, brought about American acceptance and established controlled positive-pressure mechanical ventilation as an indispensable part of conventional intraoperative management.