Case 1 A shaky excuse

Paul Turner is a 34-year-old self-employed painter and decorator who is normally fit and active. He has been diagnosed as having probable multiple sclerosis after a self-limiting episode of left hemi-sensory disturbance 3 years ago and, more recently, trigeminal neuralgia which has settled on treatment with carbamazepine 400mg bd.

Mr Turner presented to his GP with shortness of breath, a productive cough, vomiting and fever. The GP detected signs of right-sided basal consolidation on examination and Mr Turner looked ill. Worried about pneumonia, the GP has sent Mr Turner to the Acute Medical Unit (AMU). Mr Turner has no known allergies or drug intolerances.

What is your initial management?

Dr Smith, the Core Medical Trainee (CT1) on the AMU agrees that Mr Turner has a history and clinical findings suggestive of pneumonia. He documents a respiratory rate of 24, a temperature of 39.4 °C, reduced percussion note at the right base and bronchial breathing. Mr Turner’s blood pressure is 92/62 and he has a sinus tachycardia of 104. Chest X-ray confirms right lower lobe pneumonia.

Dr Smith calculates a CURB-65 score and decides that Mr Turner scores only 1 (for a raised urea), but he is aware that the patient looks more unwell than this score alone would suggest. He consults the hospital formulary and decides to admit Mr Turner and treat him with intravenous co-amoxiclav and oral erythromycin for the first 48 hours, along with 5 litres min−1 oxygen, paracetamol as required, intravenous rehydration and subcutaneous dalteparin for prophylaxis against venous thromboembolism. The Consultant Physician on take agrees with the management plan.

After 48 hours Mr Turner is generally better – his temperature has settled, he is less hypoxic and is no longer requiring supplemental oxygen. He remains lethargic and feels shaky. The intravenous cannula is removed and he continues on oral antibiotics with a plan for 7 days in total and discharge home the next day. However, on the morning of discharge the nurses report that Mr Turner is unsteady on his feet and the Ward FY1 doctor notes that he has mild truncal ataxia and a tremor. The junior doctor is concerned that Mr Turner is developing a further episode of demyelination.

What would you do now?

The FY1 telephones the on-call registrar and asks specifically about the management of an acute brainstem demyelinating episode. Without seeing the patient, the registrar suggests an MRI scan should be requested and this is scheduled for the next day. In the meantime, Mr Turner appears to be recovering well from his pneumonia but he feels nauseated, lethargic and his cerebellar signs are deteriorating. The MRI is performed the next day but is not reported until late in the afternoon – there is no clear evidence of any change compared with a previous scan performed 14 months ago and specifically there is no new cerebellar or brainstem lesion. An opinion is requested from neurology and the neurology SpR agrees to see Mr Turner the next afternoon if he can be brought down to outpatients.

What is your diagnosis?

When seen the next day by the trainee neurologist, Mr Turner is drowsy, has a marked tremor, nystagmus in all directions of gaze and is so ataxic he cannot stand. He is vomiting intermittently and feels awful. The neurology SpR is concerned about acute demyelination but also raises the possibility of an acute cerebellar syndrome associated with mycoplasma infection.

At this stage the Ward Pharmacist returns from leave and writes on the patient’s drug chart that care needs to be taken when erythromycin is co-prescribed with carbamazepine but does not contact and speak to the medical team directly.

By day 6, Mr Turner is worse and the neurology SpR decides to discuss the case with her consultant. The next morning while waiting to hear back from neurology, the consultant physician does a ward round and is very concerned about Mr Turner’s drowsiness and notes there is now new onset confusion. The drug chart is reviewed and the Ward Pharmacist’s comments are revealed. An urgent carbamazepine plasma concentration is requested and 3 hours later the laboratory confirms that Mr Turner has carbamazepine toxicity.

The FY1 crosses off the erythromycin from the drug chart and asks the nurses not to give the carbamazepine until it has been reviewed at 48 hours. He tells Mr Turner that he has ‘had a reaction to one of the tablets’ and that things should now improve. This is indeed the case and after a further 72h in hospital Mr Turner is well enough to go home. However, he still feels washed out and it takes another week before he can contemplate returning to work.

Some months later he attends his GP practice for treatment of an infected hand wound and the GP asks is Mr Turner is allergic to any antibiotics. Mr Turner says he is not sure but something happened to make him very unwell during the recent admission and so the GP checks the discharge summary and reveals that Mr Turner developed carbamazepine toxicity caused by co-administration of erythromycin. Mr Turner is angry and feels he was misled and that the treatment provided in hospital delayed his return to work. He writes a letter of complaint to the hospital asserting negligence and demanding recompense for loss of earnings and inconvenience.

Expert opinion

The initial clinical assessment was appropriate and although Dr Smith deviated from the strict letter of local guidance on antibiotic usage, it was reasonable to do so given the concern that Mr Turner was more unwell than the CURB-65 score suggested.

The use of erythromycin was debatable but the BTS guidelines do allow for its use in community acquired pneumonia. However, Dr Smith was unaware of the potential interaction with carbamazepine and did not check for possible drug interactions.

Macrolide antibiotics (and erythromycin in particular) are subject to a significant number of drug interactions because of their inhibitory effects on CYP3A4 and P glycoprotein. No doctor can be expected to remember all drug interactions and so it is essential to check (usually by referring to the interactions section of the British National Formulary (BNF)), especially when using combinations of drugs with which one is unfamiliar. Electronic prescribing will flag up potential interactions but experience with some systems shows that prescribers become fatigued by constant reminders and alerts and either mentally switch off or in fact disable software which triggers them. Remember – when you write a prescription, even if you are simply transcribing it and did not initiate therapy in the first place, you are responsible for ensuring that the details are correct and for checking interactions and incompatibilities.

The management of Mr Turner was left in the hands of junior staff between the post take ward round and day 7 – this is unacceptable and may well have contributed to the delay in diagnosis of carbamazepine toxicity.

The ward pharmacist was away but as soon as she returned she flagged up the possible interaction but failed to talk to anyone or appreciate the significance of Mr Turner’s new symptoms. Over-reliance on safety nets (like a pharmacist checking a drug chart for interactions) may reduce self-reliance and experience, and creates greater risk when the safety net fails or is absent.

Failing to give a full and accurate explanation of what has gone wrong is unacceptable. This was an example of poor prescribing practice and the consequent iatrogenic illness was entirely avoidable.

Legal comment

The letter of complaint should be responded to with a factual explanation of events. There is no scope for legal compensation under the formal NHS complaints process, although reimbursement of expenses and ex-gratia payments are permitted with no admission of liability.

The Department of Health guidance does permit a parallel investigation of a complaint and a potential clinical negligence claim, provided the complaint investigation and response does not prejudice a Trust’s ability to defend a future clinical negligence claim. This should be discussed between the Trust’s complaints manager and legal manager.

The use of the word ‘negligence’ and request for ‘reimbursement’ would indicate the likelihood of a future clinical negligence claim. If the patient wishes to pursue a claim for compensation either as a litigant in person or with the assistance of a claimant clinical negligence solicitor, the allegations will need to be reported by the Trust’s legal department to the NHS Litigation Authority (NHSLA) so that insurance reserve figures can be placed on the potential claim and an investigation of liability can take place.

Under the Clinical Negligence Pre-action Protocol, the healthcare records would need to be disclosed to the claimant, reviewed by the Trust’s legal department and comments obtained from Trust staff involved in the patient’s care to enable the Trust/NHSLA to provide a Letter of Response to the allegations within 4 months of receipt of the Letter of Claim.

In English civil tort law, an assessment is made as to whether, on the balance of probability a healthcare professional of similar seniority and speciality would have acted in the same way; or whether the care provided fell below that reasonably expected by the ‘responsible body of professional opinion’. Compensation would only be forthcoming if there has been a breach of duty of care and this had directly caused physical or psychiatric harm to the patient.

Although no individual practitioner can be expected to remember all drug interactions, they have a duty of care whenever they write up a new drug to make reasonable efforts to identify any potential problems. The interaction between macrolide antibiotics and carbamazepine is very well described and is clearly flagged up in the BNF. Failure to check for potential drug interactions and hence to take precautionary measures is a common problem.

The lack of senior clinical input between the post take ward round and the business round a week later does not represent a good level of care and might well influence the outcome of a negligence claim.

Organizational Learning is an important aspect of clinical governance. The clinical events described should have triggered an Incident Report Form to be completed by Trust staff for review by the Trust’s clinical risk team. Whilst there were no long term sequelae for this patient, the near miss should have prompted reporting and underlined the need to improve communication between pharmacy and medical team, and the need to escalate unexpected changes in the condition of a patient to senior clinical staff.

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