Hospitals have been urged to check if there are any “limitations” in their oxygen delivery systems by a safety watchdog.

Problems with oxygen in hospitals could lead to medics being forced to choose which patients should be prioritised to receive care or lowering the amount of oxygen that patients receive, the Healthcare Safety Investigation branch (HSIB) warned.

The warnings form part of an interim HSIB report on oxygen issued during the pandemic.

Investigators launched a probe after a London hospital trust declared a major incident after identifying problems with its oxygen supply.

Problems arose when two patients on a high dependency unit (HDU) were found to have lower than expected blood oxygen levels.

The medical team probed whether there was an issue with the piped oxygen supply to the unit and as a precaution the patients were moved to operating theatres where the oxygen supply was guaranteed.

Both patients saw improved oxygen levels “without any adverse affects”.

But a pressure test on the system identified a number of areas where there was a “reduced capacity” in the piped oxygen supply.

HSIB said that the pandemic has forced hospitals to reconfigure wards, and in so doing this has unbalanced the supply.

It said that trusts experiencing issues with oxygen demand have plenty of the gas but it appears the issue lies with a combination of the pipework/system used to deliver the oxygen and where patients needing it the most are cared for along the supply network.

Medics have described similar problems around the country.

HSIB suggested real-time monitoring of oxygen flow and suitable pressure alarms in individual clinical areas may ensure similar issues don’t occur.

Trusts should also ensure senior teams across hospital estates understand the limitations in their own settings and map out the capabilities of the piped system.

“The trust identified that the lack of oxygen flow available to the HDU, and the associated pressure reduction, was due to the distribution of patients and types of oxygen therapy required in other parts of the hospital,” said Scott Hislop, principal national investigator at HSIB.

“This had created excess demand on the oxygen supply system reaching the HDU.”

HSIB chief investigator Keith Conradi added: “Providing the right quantities of oxygen to patients is essential as part of any treatment regime, and we hope this bulletin and the final report will put an important additional focus not only on existing alerts and guidance but also the need for hospital teams to have a shared understanding of the limitations in oxygen systems across all clinical areas and the very real impact this has on patient safety and clinical decision-making.”

A spokesman for the NHS in England said: “As HSIB themselves recognise, there is not a problem with oxygen supply and the NHS invested over £15m for significant improvements in oxygen systems, while 30 hospitals upgraded their systems before winter – with more to be carried out in future.”