A Victorian coroner has found a prescribing error that saw a patient inappropriately treated with enoxaparin, despite already being prescribed warfarin, contributed to her preventable death.
Coroner Catherine Fitzgerald advised Melbourne’s Eastern Health to implement routine alerts in EMR, handover and prescribing systems to note that a patient is therapeutically anticoagulated, as part of a suite of recommendations in light of the death, in November 2022.
The 90-year-old patient was a living in a residential aged care facility in the Melbourne suburb of Camberwell and was transferred by ambulance to nearby Box Hill Hospital after experiencing a fall and striking her head.
The patient was on warfarin for stroke prevention, and the notes from the aged care facility made this clear, Coroner Fitzgerald ound.
She noted CT images of the patient’s brain were initially reported as showing no acute abnormalities. While she was in the ED, an abnormal ECG and elevated troponin-T level led the assessing doctor to discuss the case with a cardiology registrar.
The cardiologist gave a differential diagnosis of myocardial infarction and takotsubo cardiomyopathy and recommended a plan to commence aspirin and enoxaparin. This plan was instituted by the assessing doctor, who charted aspirin 300 mg, together with enoxaparin 80 mg 12-hourly.
But the patient’s condition deteriorated next morning, with vomiting, altered consciousness and left hemipheresis. An urgent CT showed acute right-sided subdural haemorrhage with significant midline shift, while a coagulation profile taken that morning showed INR of 1.9, suggestive of the persisting effects of warfarin.
The patient’s family was informed the patient was experiencing a terminal event. “The hospital also provided open disclosure to the family regarding the incident and explained that the provision of enoxaparin had possibly contributed to the severity of [the patient’s] subdural haemorrhage,” the coroner’s finding said.
The patient died in the early hours of November 22, 2022.
Box Hill Hospital. Source: Shutterstock
A forensic pathologist from the Victorian Institute of Forensic Medicine found the cause of death was a “right acute on chronic subdural haematoma sustained in a fall in the setting of anticoagulation in an elderly woman with multiple comorbidities”.
The addition of enoxaparin when the patient was already being treated with warfarin was “favoured” by the pathologist to have contributed to the death by potentially exacerbating subdural bleeding.
‘Multiple sources’ had details of warfarin prescription
The coroner referred the case to the Coroner’s Prevention Unit (CPU) for an independent review of the patient’s medical care.
The review noted that while the patient’s initial CT scan was considered normal, it had been misinterpreted or misreported. It did in fact show a “a minute traumatic subdural haemorrhage”, which was only identified after the patient deteriorated.
The CPU said it was highly likely a non-reversal of the pre-existing anticoagulation, from warfarin, and the introduction of excessive anticoagulation from enoxaparin and aspirin, led to the initially small haemorrhage progressing to a large one.
Sources of information available to the patient’s treating clinicians about her out-of-hospital warfarin prescription included the transfer letter from her aged care facility and Ambulance Victoria patient care records. The CPU noted “warfarin 3mg daily” had been entered into the patient’s electronic medical record in the ‘Prescriptions and documented home meds’ section.
Eastern Health acknowledged: “With the benefit of thoroughly reviewing the case in retrospect, it was evident during our organisation’s root cause analysis process that there were multiple sources of information that demonstrated that the patient was regularly taking warfarin as a home medication, and that multiple clinicians were aware of this,”
Human and system errors
Errors contributing to the patient’s death identified by the CPU included human error and “failure to adhere to basic prescribing safety”, as well as several system errors, such as the use of an electronic prescribing system which did not raise an alarm when two medications of the same class were recorded.
Further, the unit noted numerous clinical handovers failed to highlight the patient’s anticoagulation with warfarin. The CPU ventured that the cardiology registrar, who recommended a plan including enoxaparin, was not properly informed of the patient’s warfarin prescription by referring staff.
Because the initial haemorrhage was very small and subtle, the CPU suggested there was no reasonable expectation that a non-radiologist could detect it.
The coroner accepted the failure to identify this at the initial CT scan was a result of human error, and did not make any recommendations about what could prevent such an occurrence in future.
“I note that information has been provided by Eastern Health that this has been raised and addressed with the relevant radiologist,” she said.
Prescription information “overlooked”
The coroner found that while the small subdural haemorrhage was not identified immediately, the predominant factor in the patient’s preventable death was “inappropriate administration of enoxaparin”.
She agreed with the CPU’s assessment that appropriate safeguards and alerts were needed to prevent a similar situation in future.
Information about the patient’s use of warfarin was available from the outset, but “was overlooked on numerous occasions by several clinicians when it could reasonably be expected to have been noted by the medical staff with responsibility” for the patient, she said.
The coroner made five recommendations, including that Eastern Health review its ‘Post Falls Response and Management Guideline’ to include specific instructions about performing a clotting profile for patients presenting after a fall with head strike.
The hospital operator should also implement a routine alert in systems to identify when a patient is therapeutically anticoagulated, and for an alert to be triggered in the EMR when two different anticogulants are entered into the medication management system, the coroner recommended.
Eastern Health said in a statement: “Eastern Health would like to extend our sympathies to the family of Mrs Jean Crocker. We acknowledge the Coroner’s findings and conclusion. Further, we accept the Coroner’s proposed recommendations and will implement measures to prevent a similar incident occurring again.”