CARDS (COVID- ACUTE RESPIRATORY DISTRESS SYNDROME) IS DIFFERENT FROM ARDS CPAP HELMET IS THE WAY- NOT THE VENTILATOR

“The real problem of bad experiment is – when scientist is pre-fixed with outcome and designs the experiment”-

The same is true with medical profession- we have tough situation to accept fact that “Ventilators are failing” and what we thought was “wrong”

The news published in Times racked the world  states that “New York City emergency-medicine physician Dr. Cameron Kyle-Sidell sparked controversy when, two weeks ago, he posted a YouTube video claiming that ventilators may be harming COVID-19 patients more than they’re helping.”- https://time.com/5820556/ventilators-covid-19/-

Is it true- well when we ;looked at the JAMA - https://jamanetwork.com/journals/jama/fullarticle/2765302

The conventional ARDS (Acute respiratory distress syndrome)

It is caused by various medical conditions leads to “baby Lung”- leading to shrinkage of ventilatable lung and lots of fluid getting accumulated. In all such settings high levels of positive end-expiratory pressure (PEEP) shall improve

The CARDS (COVID ARDS)-

This is entirely different and patients initially retain relatively good compliance of lung despite very poor oxygenation. What you on CT scans are limited Infiltrates usually characterized by a ground-glass pattern on CT. This means interstitial (The media between circulating part and ventilatory part) part of lung is effected rather than the fluid into the lungs. In medical language they are called “type L,” characterized by low lung elastance (high compliance), lower lung weight as estimated by CT scan, and low response to PEEP

What gave us the clue and what is the evidence-

ARDS is usually bad- But for COVID-19, the numbers are even worse. Only a small portion of COVID-19 patients get sick enough to require ventilation—but for the unlucky few who do, data out of China and New York City suggest upward of 80% do not recover. A U.K. report put the number only slightly lower, at 66%.

What is the solution-

As per the JAMA article – “Patients with type L CARDS, can accept larger volumes of air compared to ARDS patients without worsening the risk of Ventilator Induced Lung Injury (VILI).

The key issue in early stage is disrupted blood vessel response. If oxygen falls- the lung vessels should contract. But it doesn’t happen in COVID because of assault to vellsel inner layers and haemoglobin. Leading to profound fall in blood levels of oxygen. The clinician’s first response is to enhance fraction of oxygen in the inhaled air- which indeed prove effective early on.

In case not sufficient, noninvasive support (eg, high-flow nasal O2, CPAP, Bi-PAP) may stabilize the clinical course in mild cases, provided that the patient does not exert excessive inspiratory efforts.

However, despite high oxygen if respiratory drive is not reduced and noninvasive support fails – it can lead to increase tissue stresses and raise pressure on lung blood vessels leading to reduced blood flows, and fluid leakage (ie, P-SILI). Progressive deterioration of lung function (a VILI vortex) may then rapidly ensue.

If you want to put them on ventilators -you need to paralyse patient which actually interrupt this cycle and make the situation worse.

The medical Jargon with conclusion

Targeting lower PEEP (8-10 cm H2O) is appropriate. Raising mean transpulmonary pressures by higher PEEP or inspiratory-expiratory ratio inversion redirects blood flow away from overstretched open airspaces, accentuating stresses on highly permeable microvessels and compromising CO2 exchange without the benefit of widespread recruitment of functional lung units.

If lung edema increases in the type L patient, either because of the disease itself and/or P-SILI, the baby lung shrinks further, and the type H phenotype progressively develops. Concentrating the entire ventilation workload on an already overtaxed baby lung increases its power exposure and blood flow, thereby accentuating its potential for progressive injury.”

The Final say

CPAP helmet is the way- so let us stop running behind ventilators and focus on the CPAP helmets- which not only improve outcomes (lesser deaths )- but also prevent cross transmission to great extent and help saving medical professionals