Historical Lessons from Twentieth-Century Pandemics Due to Respiratory Viruses

  
NCJ_cover.jpgBy Eelco F. M. Wijdicks

First Online: 12 May 2020

The medical conundrum of pandemics caused by respiratory viruses—novel or mutated—can be of interest to neurointensivists and not only those captivated by history. Rapidly compromised oxygen delivery and the possibility of consequent bacterial infections that may secondarily damage the brain create a potentially urgent situation. Moreover, and for sure in the laboratory, neurotropism of some respiratory viruses has been documented.

Neurocritical care as a specialty has a connection to the poliomyelitis epidemics of the 1950s. In fact, there has been a persistent assertion that the specialty started with the poliomyelitis pandemics, although a more accurate interpretation is that the poliomyelitis pandemics signaled the beginning of intensive respiratory care as a medical discipline. Hospitals were suddenly confronted with a devastating paralysis requiring acute ventilator support. At that time, mechanical ventilation was possible with the so-called iron lung, a tank that incorporated electrically driven blowers resulting in inspiration with negative pressures. During these early days of mechanical ventilation, hospitals throughout the world had few of these respirators available—an eerie familiarity to our current SARS-COVID-19 challenge in 2020!

One solution came from Denmark, where Lassen and Ibsen managed a growing number of admissions of patients with respiratory failure, pharyngeal weakness, and closed airways due to pooling secretions. Tracheostomy and positive-pressure ventilation made caring for patients much easier than a tank or cuirass respirator [1, 2].

Epidemics with potentially lethal respiratory viruses are physiologically different from bellows failure in bulbar forms of poliomyelitis because it involves oxygen transport and much more. These epidemics and pandemics were caused by H1N1, corona viruses (severe acute respiratory syndrome or SARS, Middle East respiratory syndrome or MERS) with patients admitted to intensive care units with acute respiratory distress syndrome and multiorgan failure. In the last three centuries, 12 pandemics have been caused by influenza A, with the most iconic known as the 1918 “Spanish flu” pandemic. Between 1933 and 1957, the world experienced nine influenza A (H1N1) epidemics and five influenza B epidemics. The worst of all these later pandemics was the 1935 and 1936 influenza B epidemics, which caused at least 55,000 deaths in USA. An animal corona virus jumped species and caused a worldwide outbreak of nearly 9000 cases of SARS from late 2002 into the summer of 2003. Now, in the middle of one of the worst pandemics due to a novel respiratory virus SARS-COVID-19, we must briefly journey through the past for insights. Three main questions can be asked, and answers may be found in the annals of medical history. First, are some respiratory viruses clinically neurotropic and damaging to the central and peripheral nervous system? Despite a handful of cases, a major neurologic syndrome or complication never materialized in influenza-like epidemics. But if so, what does the encephalitis lethargica epidemic, long considered an unexplained flu encephalitis (Grippe-Enzephalitis), tell us about the neurologic manifestations in the early and late phases? Can we expect to see long-term effects with pandemics? Second, could the injury to the nervous system be a consequence of ineffective treatment (i.e., refractory hypoxemia despite all available options) or a result of multi organ failure which may include disseminated intravascular coagulation? Third, what was the experience with the mass use of new vaccines? Such additional knowledge will be useful for the neurointensivist for when the next domino falls.

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