Breathing easier in the ICU

Reports of coronavirus victims often include pictures of intensive care units filled with intubated patients—that is, patients with breathing tubes connected to ventilators. Long used to help patients who are under anesthesia or whose breathing has failed, ventilators mechanically push air into the lungs under pressure. Like any powerful tool, they should be used wisely—and reports are starting to suggest that, in the context of the coronavirus pandemic, wise use of ventilators may mean less use of them.

COVID-19 often causes a specific type of pneumonia, leading to dramatic respiratory distress and very low oxygen “saturation.” Oxygen saturation refers to the percentage of hemoglobin (the molecule in blood cells responsible for carrying oxygen) that’s actually carrying oxygen. To measure saturation, doctors often use a “pulse oximeter” that shines light through a finger. Oxygenated blood absorbs light at one frequency and deoxygenated blood at another, and with a little automated math, the system gives an oxygen reading. A healthy percentage is in the high 90s, and more typical pneumonias don’t usually cause a dramatic “desaturation” until the patient is gravely ill.

But COVID-19 is different. Patients with COVID-19 pneumonia often enter the hospital with oxygen numbers far lower than the point at which doctors would normally rush to intubate.

Originally, doctors did indeed rush to intubate such COVID-19 patients. But two things happened: First, patients on mechanical ventilation often fared poorly. Doctors initially ascribed this to the disease’s progression—after all, they were intubating these patients precisely because they were so sick. Yet patients treated without mechanical ventilation often did better than expected clinically, despite their bad numbers on the monitor. (Exactly why patients with COVID-19 are often able to tolerate such low oxygen levels is an interesting question, but one without a satisfactory answer yet.)

In his influential work The ICU Book, intensive care physician Paul Marino argues doctors should use oxygen, ventilators, and sedation thoughtfully, seeking not to “treat the monitor” (that is, to make the best possible numbers our goal) but to provide patients with just enough support to heal. Marino suggests that even if a doctor avoids causing direct, obvious harm through ham-handed use of these tools, their effect can still be counterproductive. The goal, then, should be to conserve their use.

A treatment protocol released by Eastern Virginia Medical School (EVMS) in Norfolk, Va., follows this conservation approach for COVID-19 patients, recommending doctors avoid intubations whenever possible. Under the protocol, the first step for treating COVID-19 patients remains oxygen via nasal cannula—the ubiquitous “prongs” that longtime smokers attach to their portable oxygen concentrators. But when patients need something more, doctors are now trying high-flow oxygen via nasal cannula—and are accepting oxygen saturations in the low 80s, an idea that would have before been unthinkable. Only when this fails does EVMS suggest mechanical ventilation, and even then the goal is to use the lowest possible pressures. (As a disclaimer, the school notes “there is no known therapeutic intervention that has unequivocally been proven to improve the outcome of COVID-19.”)

I’ve heard this approach described as a way to conserve ventilators. It could have that effect, but that’s not the main idea behind it: Even where ventilators are widely available, EVMS—and Dr. Marino’s book—argue the best treatment is as gentle as possible.

As we cautiously emerge during this eye-of-the-storm phase of the pandemic, I’ll look forward to reading more of what we’ve learned from the first wave of cases.

—This story has been updated to correct the name of the Eastern Virginia Medical School.