What the First COVID-19 Autopsy Reports Tell Us 19/04/2020

What the First COVID-19 Autopsy Reports Tell Us 19/04/2020

Each day brings more information of SARS-CoV-2, its infectivity, its lethality, pathogenesis and treatment, writes Deepak Natarajan. 

One of the most striking revelations has been that patients put on ventilators do extremely badly. Just about every centre reports very high rates of death once a tube is put in a patient.

Some critical care doctors have stuck out their necks to explain that lung pathology in COVID-19 patients seems different from that of acute respiratory distress syndrome (ARDS). Dr Gattinoni Luciano, a leading intensive care expert from Italy, has suggested that the lungs of most COVID -19 patients retain their mechanical capacity to function despite severe hypoxia.

Clinicians in New York have begun to notice that patients with COVID-19 having low oxygen saturation continue to be lucid and clear. It is not uncommon to find a patient with an oxygen saturation as low as 50% speaking on the phone. The term “happy hypoxia” has been given to the condition, only for these patients to suddenly collapse. The initial paradigm of intubating patients as soon as oxygen saturation begins to drop is drawing sceptics. It is slowly being suspected that patients with COVID-19 have a unique lung disease, and not the classical ARDS.

Treating doctors have realised that somehow intubated patients fare badly, with mortality ranging from 30% to almost 100%.

One explanation discussed among critical care doctors is that air pushed in at high pressure by ventilators may be causing more harm to lungs than providing relief to them. Some doctors have noticed, serendipitously, that a patient with severe hypoxia but who is conscious did better with oxygen provided by a tube in the nostril.

One trick employed is to turn the patient to her left or right or even prone (on the tummy). There is dramatic improvement in oxygen saturation within minutes of applying this simple technique. The prime minister of England was likely treated with simple oxygen delivery. At the most he may have been given oxygen by continuous positive airway pressure.

The COVID-19 lungs seem more like they’re suffering from high-altitude sickness. As one New York doctor explained, it is like dropping someone onto the peak of Mount Everest without any time to acclimatise. The SARS-CoV-2 virus, unlike conventional pneumonia, attacks both lungs. The patients come to hospital with low oxygen levels but not in distress. The usual patient is in acute distress once oxygen drops below 80%, but not the COVID-19 patient. The COVID-19 patient has a strange slime in her air sac that prevents oxygen exchange in the lungs. Increasing the force with which the ventilator can pump in air seems to be of little or no help.

Perhaps ventilators may work at lower pressures in selected patients, but this will need a randomised controlled trial to ascertain. For now, many critical care specialists are batting for simple oxygen administration to the patient, while she is kept in a prone position. No wonder that there has been a substantial reduction in the use of ventilators in COVID-19 patients in New York city. The current mantra is to use ventilators in select cases and to push in oxygen less aggressively.( SOURCE : The Wire -CKR 20/04/2020