Editor’s note: This commentary is by Dr. Turner Osler, who is a career academic trauma surgeon at the University of Vermont Medical Center turned research epidemiologist.
As a trauma surgeon and intensivist I’ve taken care of thousands of patients on ventilators, and over the last two decades I’ve come to have a keen appreciation for what ventilators can, and perhaps as importantly, what they cannot accomplish. I’m concerned that our current infatuation with ventilators as a solution to the Covid-19 crisis radically misframes the problem. As our surgeon general has observed, “We’re not going to ventilate our way out of this problem”.
A little background: The living lung is a remarkable thing to see in the operating room. It’s soft and a beautiful shade of pink, and it fills the entire chest, expanding and contracting with every breath from the anesthesia machine. Amazingly, with patient, gentle pressure, an entire lung can be gently squeezed until it exhales all its air, and shrinks enough to fit in the palm of one hand, now turned a blue and apparently lifeless blob. But just a few quick breaths pushed into the lung causes it to spring back to life, its normal size and shape and color restored, no worse for the wear. It’s amazing, really, just how tough the lung is.
At the cellular level, the lung is still more amazing: a delicate mousse of air, blood, and lung tissue, a brilliant arrangement that allows air to come and go with every breath, and allows the blood to come into intimate contact with air, although never quite mixing. This intimacy is essential, because it allows the blood to pick up oxygen and offload carbon dioxide into the lung’s air spaces. If this amazing arrangement is disturbed by, say, swelling of the thin layer of tissue that separates the air sacks (alveoli) from capillaries, blood oxygen levels plunge, and death follows in short order.
Now it happens that the lung’s alveoli are richly covered in ACE2 receptors, and unfortunately the coronavirus selectively attaches to these receptors. This is bad, because we don’t yet have an antiviral agent effective against this coronavirus. In other situations, it’s usually not catastrophic, because the body’s immune system can deal with viral attacks. Unfortunately, for reasons that we don’t yet understand, some people’s immune systems go over the top, and in these people the collateral damage to their lung tissue by their own immune system can be devastating. When the damage to that patient’s is so great that they can’t keep up with the body’s oxygen needs, a ventilator can buy time by providing deeper, faster breaths than patients can muster on their own.
So, the ventilator can buy time, but time for what? In ordinary circumstances, the lung is damaged by some reversible insult, most commonly a bacterial infection. In this happy circumstance antibiotics can usually dispatch the invaders, and with the infection routed the patient’s lung can go to to repair itself; soon enough the ventilator isn’t needed and can be removed.
But if, as is sometimes the case in Covid-19 patients, the lung is subject to ongoing attack by the patient’s own immune system, the lung may never heal. The lung becomes a solid mass of tissue containing little air and with scant air flow in and out despite the ventilator’s maximal settings. Worse yet, by subjecting the lung to high oxygen concentrations and high pressures the lung is further injured, and the downward spiral of adult respiratory distress syndrome begins. In this scenario the ventilator is no longer prolonging life; it is prolonging death.
And here’s the thing: although good, data driven, estimates are not yet available it seems that the mortality for Covid-19 patients who require mechanical ventilation is very high, likely over 50%, and perhaps a good deal higher.
Here’s the point: By the time you’re on a ventilator it may be too late for a good outcome. The effort, discomfort, and substantial risk of an ICU admission are far better avoided than endured. Ventilators have been oversold as a solution, because the lung injury caused by Covid-19 often isn’t amenable to our usual tools of ICU care. Once you’re in the ICU, the die is cast; far better never to find yourself in the ICU in the first place.
A drug to treat Covid-19 before things get this grim would of course make ventilators irrelevant, and the hunt is on. And eventually a vaccine will render Covid-19 specific treatments a footnote in medical history books. But until specific treatments for Covid-19 infection become available, avoidance is the only reliable strategy.
I write this in hopes of recasting the Covid-19 problem. We must move from: “We need more ventilators” to “We need more scrupulous, and more uncompromising social distancing.” I’m dismayed by the amount of air time spent on counting ventilators, bidding for ventilators, fighting over ventilators … ventilators which in the end may not do much to change outcomes. Time would be far better spent emphasising and creatively explaining social distancing. Like this.
We humans generally prefer easy, after-the-fact fixes for problems: a treatment, a pill, a machine. However, it’s usually the less glamorous approach involving some simple behavioral tweak that’s more successful, and this is especially true for Covid-19.
So, “Do your part and stay apart.” Pass it on so you won’t pass it on.
