robert wachter, chairman of the department of medicine at the university of california san francisco.r. wachter, thank you for sticking with us. >> pleasure. >> before we -- before we took that break, you were affirming the concerns that have been voiced by anonymous white house officials tonight to "the new york times," and that we've heard other people discuss in recent days, that the president may be impaired in his decision-making and his thinking, both by covid and potentially by some of the treatments that he's on, specifically thinking about that steroid. you said that among the hundreds of patients that you have treated who have had some sort of impairment like that, you wouldn't trust them essentially to decide whether or not they are impaired. as a physician, is there the -- is there testing that you do? is there a way that you can discern whether or not somebody is impaired in their thinking or their ability to understand or impulse control or anything else that might be affected by these drugs or by this illness? >> well, it's a little tricky because obviously some of this

robert wachter says the next seven to ten days are vital to see how the president responds. abc 7 news reporter luz pena has more from dr. wachter. >> i came here, wasn't feeling so well, i'm feeling better now. >> reporter: dr. robert wachter, chair of the department of medicine at ucsf, says the president's health remains uncertain. >> we certainly see people that do this, they come up a little bit, and the next day they crash. >> reporter: dr. wachter's biggest concern was that president trump was allegedly given oxygen at the white house, indicating the virus may have affected his lungs. >> now that his oxygen level has fallen, we know he is at risk of a bad case of covid pneumonia. the key is his oxygen level is low, because people in the emergency systems slap on a little oxygen, it's not a big deal. but knowing he did get it because he actually needed it is very important. >> reporter: a diagnosis that according to a uc hatine in esenal .yi ride on a wave of he sympat sympathy. >> reporter: it's a question that lingers. if the 25th amendment is invoked, who would be o

robert wachter, chair of the department of medicine at ucsf says the president's health remains uncertain. >> we certainly see people that do this, and they come up a little bit, and the next day they crash. >> reporter: dr. wachter's biggest concern is that president trump was allegedly given oxygen at the white house, indicating the virus may have affect his lungs. >> reporter: now that his oxygen level has fallen we know that he is at risk of bad case of covid pneumonia. the key is that his oxygen level is low. sometimes people come to the emergency department and we sometimes slap on a little oxygen. it's not a big deal. knowing he did get it because he actually needed it is very important. >> reporter: a diagnosis that of course uc hastings law professor could potentially change the presidential race. >> this could play either to his detriment with people who will be accusing him of downplaying the pandemic and sort of learning from his own mistakes, or he could ride on a wave of sympathy from behind and recover the problems with his current campaign. >> reporter: now exactly a month

robert wachter says the president's health remains uncertain. >> we certainly see people that do this and they come up a little bit and the next day they crash. >> reporter: the doctor's biggest concern is that president trump was allegedly given oxygen at the white house, indicating the virus may have affected his lungs. >> now that his oxygen level has fallen, he is at risk of a bad case of covid pneumonia. the key is that his oxygen level is low, sometimes we slap on a little oxygen, but knowing he h needed it is very important. >> reporter: the diagnosis that according to uc hastings law professor hadar avaren who change the presidential race. >> this will be a detriment people aus coaccusing him of downplaying the pandemic or rising from behind. >> reporter: there is a question that lingers. if the 25th amendment is invoked, who would be under the hood? >> pence will take over the presidential duties temporarily while trump remains on the ballot. >> reporter: president donald trump is 74 years old and clinically overweight, two factors that place him under the high risk category

robert wachter says the president's health remains uncertain. >> we certainly see people that do this and they come up a little bit and the next day they crash. >> reporter: dr. where biggest concern is that president trump was allegedly given oxygen at the white house, indicating the virus may have affected his lungs. >> now that his oxygen level has fallen, he is at risk of a bad case of covid pneumonia. the key is that his oxygen level is low, sometimes we slap on a little oxygen, but knowing he did get it because he actually needed it is very important. >> reporter: the diagnosis that professor hadar avaren could change the presidential race. >> this will be a detriment people accusing him of downplaying the pandemic or learning from his own mistakes or he could ride on a wave of sympathy from behind and recover the problems with his current campaign. >> reporter: there is a question that lingers. if the 25th amendment is invoked, who would be under the hood? >> what might happen is that pence will take over the presidential duties temporarily while trump remains on the ballot. >>

robert wachter, chairman of the university of california at san francisco's department of medicine said any patient of his with trump's symptoms and treatment who wanted to be discharged from the hospital after three days would need to sign out against doctor's orders because it would be so ill advised. wachter says, quote, for someone sick enough to have required remdesivir and dexamethasone, i can't think of a situation in which a patient would be okay to leave on day three, even with the white house's medical capacity. william schaffner, professor of infectious diseases at vanderbilt's medical school concurring, saying the idea of sending trump back to the white house today, that idea, quote, absolutely not. but there he is and taking off the mask right before he walks inside the white house, gasping for air. why is the president getting this treatment that dr. conley has described? do we believe that this is the treatment the president is getting? i ask because dr. conley's pronouncements have been hard to believe at times, often inconsistent, and they've required repeated correctio