Medics are worried about how they will cope if they are forced to ration intensive care provision, a leading doctor has warned.
Professor Rupert Pearse said intensive care doctors were fearful of "moral distress"- when they know the right thing to do for a patient but are unable to do so as a result of "institutional" constraints – or the risk of legal challenge.
"If doctors are afraid to make decisions it will be worse for everyone," he warned.
His comments come after Boris Johnson warned there was a "very substantial" risk of intensive care units being overwhelmed by the current wave of Covid-19 cases.
Prof Pearse said it was important that medics were only faced with the prospect of denying an intensive care bed to someone who needs it if there was a national emergency – if units across the country are overwhelmed.
He said: "The burden of decision making around ICU (intensive care unit) admission traditionally falls on senior ICU doctors.
"Most of us are privately very worried about what will happen if we run out of resources."
So far the system has coped, even at the peak of the first wave, and Prof Pearse said he was not aware of any patient who was not admitted to ICU when the consultant responsible believed they should have been.
But there is a framework for dealing with that system – the Critcon levels, which go up to Critcon 4, an emergency situation where ICU treatment may have to be rationed because there are no beds available elsewhere.
The Intensive Care Society (ICS) said the aim is that no hospital reaches Critcon 4 until all possible mutual aid has been exhausted, and every other ICU across the country is at Critcon 3 – where they are at maximum physical capacity including all expansion areas in use.
The ICS said there was "intentionally a very clear threshold for Critcon level 4 which must be nationally agreed and declared".
Prof Pearse said: "We should never choose between patients unless Critcon level 4 is declared at a national level."
While ICU doctors make difficult decisions every day for individual cases "we never want to choose between patients", he said.
"Many doctors would like official guidance," he added.
On Wednesday, the Prime Minister told MPs: "If you ask me when do we think that the ICU capacity is likely to be overtopped, I can't give you a prediction for that.
"But all I can say is that the risk is very substantial and we have to keep the pressure off the NHS and the only way to do that is to follow the current lockdown."