There can only be a specific number of ECMO units surely...
I didn't say that there wasn't a finite number of ECMO patients that can be treated at any one time, but that the numbers can be increased above the usual capacity if necessary and possible due to the other constraints I mentioned.
Are you sure you mean ECMO and not ICU?
Given that ECMO is my job (being general so as not to out myself) then, yes I'm confident that I know the difference.
The number of ECMO machines is only part of the picture - each of the 5 UK retrieval centres will have many more than 1 actual machine, but it also requires highly trained specialist nurses, doctors and clinical scientists to look after the patients on ECMO. To my knowledge no patient in the UK who meets the criteria for respiratory ECMO support has been turned away because of lack of capacity since the service was commissioned following the swine flu pandemic. However, it would not be possible to put large numbers of coronavirus patients on ECMO at any one time. Wales doesn't have its own retrieval centre, however they are covered by the English centres.
It's also worth pointing out that we don't actually know whether ECMO would increase survival of coronavirus patients. The evidence in favour of respiratory ECMO for non-coronavirus ARDS is not conclusive, although I think most of us involved in it do strongly believe that it benefits many of the patients who are placed on it. However, it does appear that being treated in a respiratory ECMO centre increases survival, probably because of the specialist skills in treating these patients. So it may be (speculating here) that these centres will have a role to play in looking after patients even where they do not have ECMO capacity. Obviously this will have a knock-on effect in terms of their other services though.