More operations have been cancelled today at north Cumbria's hospitals, following problems.
A total of 16 planned procedures were halted yesterday after it emerged some anaesthetic machines had missed vital servicing checks.
Engineers were brought in to carry out urgent safety tests on the affected equipment.
Bosses have today confirmed that a "small number" of elective operations have again been cancelled, along with others planned for tomorrow.
Most of them are at the Cumberland Infirmary in Carlisle, though the West Cumberland Hospital is also affected.
North Cumbria University Hospitals NHS Trust stressed that all urgent surgery, including maternity and cancer patients, is going ahead - using machines that are within their service date.
An investigation has been launched to find out exactly how the machines could have missed these crucial checks.
One hospital insider has claimed the machines should have been serviced weeks ago.
All patients whose operations are affected will be contacted directly by the trust.
Everyone else should attend hospital for surgery as previously arranged.
Mandy Nagra, executive chief operating officer at the hospitals trust, said the cancellations were a precautionary measure.
She added: “We apologise for the short notice cancellations. We will ensure the patients who have been postponed are rearranged as soon as possible.
“Our emergency procedures have gone ahead.”
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