Operations have been cancelled at Birmingham's largest hospital trust because of a shortage of intensive care beds.
A lack of staff at the Queen Elizabeth Hospital is thought to be the reason its ICU is running at full capacity.
John Gallivan, from Herefordshire, had his surgery cancelled on the morning he was due to have an operation.
University Hospitals Birmingham NHS Foundation Trust said it was "expanding capacity and opening up more beds".
The trust said it was still having to cancel some scheduled procedures and could only apologise to those affected.
Its Intensive Care Unit, also known as an Intensive Therapy Unit, provides beds for some of the most critically ill patients.
The hospital trust said the department was currently at 100% capacity, based on staffing ratios, although these could be adjusted.
Sources have told the BBC intensive care staff are either sick or have left the unit, BBC Midlands Today health correspondent Michele Paduano said.
Mr Gallivan, who was waiting for heart surgery, said: "I was told by the surgeon I was first on the list for theatre at 07:30 in the morning.
"Seven-thirty came along and no one came to collect me, and then about an hour later, two senior nurses came in with the surgeons to tell me the bad news that there was no ICU beds available at the moment so my appointment was suspended."
Dr Nick Rutter from City Hospital, which is also almost at capacity, said the numbers were not a "good place to be in going into winter", but said the "Black Country as a whole isn't too bad".