Health inspectors had to intervene to ensure a patient with sepsis received treatment during a routine visit at a struggling hospital.
Staff at Russells Hall Hospital in Dudley failed to properly monitor the patient, who was not given antibiotics for two hours, a report said.
The Dudley Group NHS Foundation Trust was given an “requires improvement” rating by the Care Quality Commission.
A serious case review into the incident is under way.
The report said “the inspection team had to intervene to ensure a patient was reviewed and attended to as a matter of urgency.”
It added: “This patient in particular was admitted early in the morning and placed on the sepsis pathway, but did not receive antibiotics until two hours later and did not receive timely observations.”
The health regulator said it was concerned by a lack of safety and leadership in the emergency department and rated its services as “inadequate”.
Chief inspector Ted Baker said: “Patients attending the emergency department did not always receive robust and sufficient assessment.
“This posed a significant risk that life-threatening conditions would not be identified and treated as quickly as they should have been.”
Senior department leaders cited overcrowding as a reason for “significant lapses in care” but inspectors found there were times when the department was overstaffed and had below the average number of patients.
Senior clinicians were found to deliberately leave blood saturation readings off a national scoring system which is used to identify acutely ill patients.
One consultant told inspectors doing so would “trigger too many emergency calls”.
Elsewhere in the report, the hospital was rated “good” for overall care provided by staff but “requires improvement” as to whether the services were safe, effective, responsive and well-led.
The trust said it has put an improvement plan in place for the emergency department to ensure patient safety.