Medical Errors and Open Disclosure — DCE Clinical Case

Long Case — A tenfold insulin overdose and a failure to cease metformin in acute kidney injury

Patient scenario

Mr Robert Hayes is a 72-year-old man admitted to the general medical ward with a three-day history of productive cough, fever, and pleuritic chest pain. A chest X-ray shows right lower lobe consolidation, and he is commenced on intravenous benzylpenicillin and oral doxycycline for community-acquired pneumonia. His past medical history includes type 2 diabetes (HbA1c 72 mmol per mol, on metformin 1 g twice daily and gliclazide 80 mg daily), ischaemic heart disease (prior non-ST-elevation myocardial infarction, on aspirin, atorvastatin, metoprolol, and ramipril), and stage 3 chronic kidney disease (baseline creatinine 140 micromoles per litre, eGFR approximately 45 mL per min per 1.73 m squared). [1]

On day two of the admission, his creatinine has risen to 230 micromoles per litre (eGFR approximately 28) consistent with an acute kidney injury secondary to sepsis and dehydration. Despite the AKI, his usual morning metformin 1 g is continued by the day team without review. The evening handover notes the rising creatinine but does not flag the need to review insulin or metformin dosing. [1]

At 0200 hours, the night-shift registrar reviews a blood glucose of 14 mmol per litre and prescribes rapid-acting insulin, writing the order as 4U on the medication chart. The overnight nurse, reading the U as a zero in the dim light and under time pressure, draws up and administers 40 units of rapid-acting insulin subcutaneously. Within 90 minutes the patient becomes drowsy and diaphoretic; a blood glucose level is 1.1 mmol per litre. He is given 50 per cent intravenous dextrose (50 mL) with partial recovery, but he re-develops hypoglycaemia twice more over the next six hours and is transferred to the intensive care unit for a dextrose infusion and ongoing monitoring. He makes a full neurological recovery over 24 hours and is transferred back to the ward. [1]

The ward consultant is notified at 0700. The medication chart, the insulin pen, and the prescription are preserved. The patient's wife, who has been at the bedside, is aware that her husband was "given too much insulin overnight" because she overheard the nurses, but she has not yet been given any formal explanation. [1]

Candidate's opening statement (SASPOP)

"Mr Robert Hayes is a 72-year-old retired engineer presenting with a two-day admission for community-acquired pneumonia, complicated overnight by a tenfold insulin overdose — 40 units instead of 4, from a prescription written as 4U and read as 40 — causing profound neuroglycopenic hypoglycaemia (glucose 1.1 mmol per litre) requiring 50 per cent intravenous dextrose and ICU transfer. He has made a full recovery. Concurrently his metformin was not ceased despite a rising creatinine from 140 to 230 micromoles per litre, exposing him to lactic acidosis that did not eventuate. [1]

His problem list is: (1) a preventable adverse event — a tenfold insulin overdose — that has caused harm and requires stabilisation (achieved), evidence preservation (achieved), and structured open disclosure; (2) a concurrent medication-monitoring error — the failure to cease metformin in acute kidney injury — that did not cause harm but is part of the same system failure; (3) community-acquired pneumonia with evolving acute kidney injury requiring ongoing treatment; (4) the medico-legal and reporting obligations — incident report, medical defence organisation notification, and an assessment of AHPRA mandatory notification and coronial referral (neither triggered); (5) the root cause analysis and the system changes to prevent recurrence; and (6) the second victim — the prescribing registrar and the overnight nurse — who require support within a just culture. [1]

This is a patient safety incident whose management is as important as the clinical care. My immediate priorities were, in order: stabilise the patient (done), preserve the evidence (done), and notify the consultant and the medical defence organisation. My next steps are to conduct the staged open disclosure with the patient and his wife, file the incident report, and convene a root cause analysis." [1]

Structured problem list and integrated management plan

Problem 1 — The tenfold insulin overdose (preventable adverse event). The patient has been stabilised in ICU and has made a full recovery. The medication chart, the insulin pen, and the prescription are preserved. The consultant and the medical defence organisation have been notified. The immediate next step is the initial disclosure with the patient and his wife (see Problem 5). A formal root cause analysis will be convened. This is NOT a never event (insulin abbreviation error is not on the never-event list) and NOT a near miss (the error reached the patient and caused harm). [1]

Problem 2 — Failure to cease metformin in acute kidney injury. The metformin has now been ceased. The acute kidney injury is being managed with intravenous fluids and treatment of the underlying sepsis, and the creatinine is trending down. This is a monitoring error — a failure to act on the rising creatinine — that did not cause harm but is part of the same system failure (inadequate medication review at the evening handover). It will be included in the same root cause analysis. [1]

Problem 3 — Community-acquired pneumonia with acute kidney injury. Continue the intravenous benzylpenicillin and oral doxycycline (dose-adjust for eGFR). Monitor the creatinine, the inflammatory markers, and the oxygenation. The CURB-65 score is 2 (age over 65, elevated urea), supporting inpatient treatment. Plan de-escalation to oral antibiotics as the patient improves. [1]

Problem 4 — The medico-legal and reporting obligations. The internal incident report is filed for every adverse event and triggers the severity assessment and the RCA. The medical defence organisation is notified of the serious adverse event and before any formal statement. AHPRA mandatory notification is NOT required — the threshold is notifiable conduct (intoxication, sexual misconduct, impairment placing the public at risk, a significant departure from professional standards), and an unintentional abbreviation error by an otherwise competent clinician is an error, not notifiable conduct. Coronial referral is NOT required because the patient recovered — had he died, the death would have been reportable as an unexpected death resulting from a medical intervention. [1]

Problem 5 — The open disclosure. Conduct the initial disclosure as soon as practicable and within 24 hours, now that the patient is back on the ward and able to participate. In a private room with the consultant, the patient, his wife (with the patient's consent), and an open disclosure facilitator, I would: open with an apology — an expression of regret that is explicitly NOT an admission of legal liability under Australian civil liability legislation; give a factual, plain-language account — that an insulin dose ten times the intended amount was given overnight due to a prescribing abbreviation, and that the metformin was not stopped when the kidneys failed; acknowledge the impact — the hypoglycaemia, the ICU stay, the fear that the patient and his wife experienced; state what is being done — a formal root cause analysis; offer support — a second opinion, counselling, advocacy; and invite questions. I would not speculate about the cause or blame the nurse or the registrar. I would document the conversation and arrange the follow-up and the formal disclosure meeting once the RCA is complete. [1]

Problem 6 — The second victim. The prescribing registrar and the overnight nurse are second victims. The registrar is likely to suffer acute distress, intrusive thoughts, loss of confidence, and, in severe cases, suicidal ideation. The response is immediate peer support, timely debriefing, removal of blame within a just culture, access to the employee assistance programme and the medical defence organisation, and a structured re-entry to practice. This was a human error (an inadvertent abbreviation, a missing check), so the just culture response is to console the individuals and fix the system, not to discipline. [1]

Discussion questions

"Classify this event using the patient-safety taxonomy." [1]

This is a preventable adverse event — an injury caused by medical management rather than by the underlying pneumonia, resulting in ICU transfer. It is not a near miss (the error reached the patient and caused harm). It is not a never event (insulin abbreviation error is not on the never-event list). In Reason's taxonomy it is an error of execution (the plan to give 4 units was correct, but the execution failed through the ambiguous prescription) and a rule-based mistake (a non-compliant local habit of abbreviating units) compounded by a lapse at the administration step (no independent check) [1].

"Apply the Swiss cheese model to this event." [1]

The layers of defence were: the organisation's policy (prohibits the U abbreviation but did not enforce it — a latent condition); the prescribing step (the registrar wrote 4U — an active failure); the pharmacy review (the order was not reviewed by a pharmacist overnight — a latent condition in after-hours prescribing); the administration step (the nurse read 4U as 40 and gave it, with no independent double-check — an active failure and a latent condition in the absence of a mandatory check for high-alert medicines); and the monitoring step (the hypoglycaemia was recognised and treated — this defence held). The durable fixes are at the latent-condition level. [1]

"What would you say in the disclosure conversation?" [1]

I would open with an apology — an expression of regret that is not an admission of liability. I would give a factual account in plain language: that an insulin dose ten times the intended amount was given overnight due to a prescribing abbreviation, and that the metformin was not stopped when the kidneys failed. I would acknowledge the impact. I would state that a formal root cause analysis is underway. I would offer support. I would not speculate or blame [3].

"Is the apology an admission of liability?" [1]

No. The civil liability legislation of the Australian states expressly provides that an apology is not an admission of liability and is not admissible as evidence of liability. The Australian Open Disclosure Framework restates this. The ethical duty of candour requires the apology, the law protects it, and the evidence shows that open disclosure with a genuine apology reduces the number and value of civil claims [2].

"What are the root causes you would expect the RCA to find?" [1]

Using the London Protocol: patient factors (complex comorbidity making the dose critical); task factors (the sliding-scale protocol lacked a forcing function); individual factors (the abbreviation, the missing check); team factors (the evening handover did not flag the rising creatinine); environment (the ward, the after-hours staffing); organisation (the persistence of the U abbreviation in practice, the absence of an independent double-check for insulin, the absence of a hard alert for high-dose insulin in renal impairment); institutional context (the accreditation of the insulin-prescribing process). The durable fixes are at the latent-condition level. [1]

"How do you apply the just culture algorithm?" [1]

This was a human error (an inadvertent abbreviation, a missing check), so the response is to console the individuals and fix the system, not to discipline. Both the registrar and the nurse are second victims who require peer support, debriefing, access to the employee assistance programme and the medical defence organisation, and a structured re-entry to practice. [1]

"What are the reporting obligations?" [1]

The internal incident report is filed and triggers the RCA. The medical defence organisation is notified. AHPRA mandatory notification is NOT required (an unintentional abbreviation error is not notifiable conduct). Coronial referral is NOT required (the patient recovered). These are three distinct pathways that run in parallel. [1]

Short Case Discussion — Error types and contributory factors

Examiner: "A patient on warfarin for atrial fibrillation is admitted with a community-acquired pneumonia and started on clarithromycin. Five days later the INR is 9.5 and the patient has an intracranial bleed. Walk me through the contributory-factor analysis." [1]

"This is a preventable adverse event — an intracranial bleed caused by a supratherapeutic INR, itself caused by a macrolide-warfarin interaction that potentiated the anticoagulation. The contributory-factor analysis using the London Protocol: patient factors — the patient was on warfarin with a narrow therapeutic index; task factors — the prescription of clarithromycin to a warfarinised patient without a plan to check and adjust the INR is the active failure at the prescribing step; individual factors — the prescribing clinician did not recall or did not check the interaction, and the monitoring (INR) was not scheduled; team factors — the interaction was not flagged at the pharmacy review, which is a latent condition if the pharmacy system lacks interaction checking for warfarin; environment — the ward; organisation — the latent conditions, the absence of clinical decision support that flags the warfarin-macrolide interaction, the absence of a protocol for INR monitoring when an interacting drug is started; institutional context — the formulary and the decision-support configuration. The durable fixes are a warfarin-interaction alert in the prescribing system, a mandatory INR-check prompt when an interacting drug is started, and patient education to report bleeding. The active failure (the prescription without a monitoring plan) is proximate; the latent conditions (the absence of decision support and protocol) are the root causes." [1]

Examiner: "Define the four elements of open disclosure." [1]

"The four elements are: an apology (an expression of regret, not an admission of liability); a factual explanation (a plain-language account of what is known and what is not); an acknowledgement (a recognition of the impact on the patient); and a plan to prevent recurrence (what is being done and what will be done differently). These four are constant across the Australian Open Disclosure Framework, the English statutory duty of candour, and the US CANDOR toolkit." [1]

Examiner: "What is a never event? Name three." [1]

"A never event — also termed a sentinel event — is a serious, largely preventable patient safety incident that should not occur if the available preventions are in place. Three examples are wrong-site surgery, a retained foreign object (swab or instrument), and an incompatible blood transfusion. Others include wrong-patient surgery, wrong-procedure surgery, and medication error leading to death or severe harm. Never events trigger a mandatory organisational response — a full root cause analysis and external reporting to the ACSQHC." [1]

Examiner: "What is the second victim and how do you manage it?" [1]

"The second victim is the clinician involved in the adverse event. The course is predictable: acute distress, intrusive thoughts, loss of confidence, defensive practice, burnout, depression, and, in severe cases, suicidal ideation. Management is immediate peer support, timely debriefing, removal of blame within a just culture, access to the employee assistance programme and the medical defence organisation, and a structured re-entry to practice. Failing to support the second victim is itself a patient-safety risk because the distressed clinician is more error-prone." [1]

Examiner: "When would you make a mandatory notification to AHPRA?" [1]

"I would make a mandatory notification to AHPRA when I form a reasonable belief that a registered health practitioner has engaged in notifiable conduct: practising while intoxicated by alcohol or drugs, sexual misconduct in connection with practice, placing the public at risk of substantial harm because of an impairment (physical or mental), or a significant departure from accepted professional standards. The threshold is public protection, the report is to AHPRA, and mandatory notification is distinct from the internal incident report. An unintentional error by an otherwise competent clinician is not of itself notifiable conduct." [1]