Standing on the steps of Walter Reed National Military Medical Center on Monday, with a phalanx of white-coated doctors behind him, the White House physician, Dr. Sean P. Conley, ticked off President Trump’s encouraging vital signs: no fever, only slightly elevated blood pressure and a blood oxygen level in the healthy range.
“He’s back,” Dr. Conley said later in the news conference.
But when reporters asked him for results of Mr. Trump’s chest X-rays and lung scans — crucial measures of how severely the president has been sickened by Covid-19 — Dr. Conley refused to answer, citing a federal law that restricts what doctors can share about patients.
Without critical data about his lung function, medical experts in Covid-19 and lung disease said they were struggling to piece together an accurate picture of how Mr. Trump is faring. They noted that while most patients with the virus do recover, it was premature to declare victory over an unpredictable, poorly understood virus that has killed more than 210,000 people in the United States.
Less than a month from Election Day, Dr. Conley’s patient, Mr. Trump, is presenting himself as strong and unfazed by the coronavirus, and seems to have instructed his doctor to steer clear of disclosing health details that might puncture his image of invulnerability.
Dr. Conley said on Tuesday that Mr. Trump was experiencing no symptoms of the disease and doing “extremely well,” though he himself cautioned on Monday that the president was not “out of the woods” and that “we will all take that final deep sigh of relief” if he still feels well next Monday.
Far from having vanquished Covid-19, the outside doctors said, Mr. Trump is most likely still struggling with it and entering a pivotal phase — seven to 10 days after the onset of symptoms — in which he could rapidly take a turn for the worse. He’s 74, male and moderately obese, factors that put him at risk for severe disease.
“I don’t need to get in the president’s business,” said Dr. Talmadge E. King Jr., a specialist in pulmonary critical care and the dean of the UCSF School of Medicine. However, he said, “if their goal is for us to understand more completely what is going on, they have left a lot of very useful information off the table.”
Several medical experts said that based on the incomplete information Mr. Trump’s medical team had provided, the president appeared to have at least at some point experienced a severe form of Covid-19, with impairment of the lungs and a blood oxygen level below 94 percent, which is a cutoff for severe disease.
But again, Dr. Conley has not been fully forthcoming about Mr. Trump’s oxygen levels. He said that the president’s blood oxygen had dipped to 93 percent on Saturday. He was evasive about an earlier episode of low oxygen on Friday, though. When a reporter asked if Mr. Trump was ever below 90 percent, Dr. Conley said that his oxygen level had never dropped to the “low 80s,” leaving open the possibility that it had fallen into the high 80s, which experts said would be troublingly low and a sign of very serious illness.
“We go crazy when it gets to 88 percent,” Dr. King said.
Mr. Trump was twice given oxygen, Dr. Conley has said, and on Saturday was started on a steroid, dexamethasone, which is recommended only for Covid-19 patients who have severe or critical forms of the disease. Mr. Trump also received an infusion of an experimental antibody cocktail and is getting a five-day course of the antiviral drug remdesivir.
Dr. Conley said on Monday that Mr. Trump did not need any oxygen and had not complained of trouble breathing. He said that the medical team had prescribed dexamethasone after Mr. Trump required oxygen and that the doctors had weighed the risks and benefits.
But Dr. Conley has not provided a complete list of the drugs Mr. Trump is receiving, saying, “I’m not going to go into specifics as to what he is and is not on.”
Some experts said that the decision to give Mr. Trump dexamethasone could be a sign that he was struggling with more serious Covid-19 than his doctors were revealing, or that his doctors had inappropriately prescribed him the drug.
“Does he have lung involvement? My guess is yes, because they did give him a lot of medications that they would only give to someone who did,” said Dr. Mangala Narasimhan, a pulmonologist and director of critical care services at Northwell Health in New York.
A large study of the drug in the United Kingdom found that it benefited Covid-19 patients who fell into those two groups and might be risky for patients with milder symptoms, tamping down an immune system that was effectively fighting the infection rather than quieting one that had gone dangerously into overdrive.
Dr. Craig M. Coopersmith, the director of the Emory Critical Care Center in Atlanta and a member of the National Institutes of Health panel that issued the dexamethasone guidelines, said that because Mr. Trump received at least some oxygen, his doctor’s decisions were understandable.
“Starting somebody on steroids when they hit a threshold of being in severe disease — even with low levels of oxygen — is both aggressive and reasonable,” he said.
As his treating physician, Dr. Narasimhan said she would have wanted to see the results of a lung scan, as well as lab tests showing inflammation and immune response. “We would watch those things very carefully, which we don’t have,” she said.
On Saturday, Dr. Conley noted that Mr. Trump had fared well on a spirometry test, which measures lung capacity. “He’s maxing it out,” Dr. Conley said. “He’s doing great.”
However, Dr. Narasimhan and others said a spirometry test was virtually meaningless with Covid-19 patients. “It doesn’t tell us anything and it’s not something we use in this disease,” she said.
Lacking crucial details from the president’s medical team, some outside doctors tried another tack — evaluating the patient themselves. On Monday, in a highly choreographed event that was covered live on some cable channels, Mr. Trump was flown to the White House, where he left the Marine One helicopter, crossed the lawn and walked up a set of stairs, to what looked like an illuminated stage set. At the top, he removed his mask, placed it in his pocket and flashed two thumbs up.
For many, it was a political stunt. For Dr. King of UCSF, who was watching on C-SPAN, the return to the White House was an opportunity to observe how the president breathed.
“As a pulmonologist, he did two things for me: He did a walk test, and he did a stair-climbing test,” Dr. King said, adding that even with the availability of sophisticated technology, lung doctors still rely on these old-fashioned tests “to just get a picture of how the patient’s doing.”
Dr. King said what he saw concerned him. Mr. Trump paused twice while walking across the lawn — whether to wave to cameras or to catch his breath, he said was not clear — and then appeared to be gasping for breath at the top of the stairs. He and others said Mr. Trump used his neck muscles to help him breathe, a classic sign that someone’s lungs are not taking in enough oxygen.
“This suggests that something’s going on, I don’t know what or to what extent,” Dr. King said. “Any pulmonologist, I think looking at that would give them pause. And you’d say, well, what else do I not know about his condition that I would want to know?”
Dr. Ilan Schwartz, an infectious disease doctor and assistant professor at the University of Alberta, agreed. “As a physician, I would refrain from commenting on somebody whom I haven’t examined,” he said. “But in this case, the clinical signs are so obvious that it can be seen from a distance, even on a short two- or three-second clip.”
The odds are that Mr. Trump will recover from the virus, said Dr. Michelle Prickett, an associate professor in pulmonary and critical care medicine at the Northwestern University Feinberg School of Medicine.
“The vast majority of patients that have this will get better, and anyone who has treated this is hoping that every patient is in that category,” she said. But for doctors like her who have treated many Covid-19 patients, “we’ve all seen too many examples of worst-case scenarios.”