The triple whammy: an older man with heart failure, CKD and a self-purchased NSAID

Drug-related problems, in order of immediate danger:

1. Ibuprofen in a patient with CKD and heart failure - an NSAID bought without prescription review. This is the precipitant.
2. Metformin 1 g twice daily at an eGFR of roughly 26 mL/min/1.73 m^2 - contraindicated below 30 mL/min/1.73 m^2 and, independently, must be withheld during any acute illness with dehydration or AKI.
3. Ramipril during an AKI with hyperkalaemia - an ACE inhibitor that should have been suspended the moment renal function fell.
4. Furosemide in a volume-depleted patient - contributing to prerenal injury, and now a source of further potassium loss only if perfusion is restored.

Mechanism - the 'triple whammy': glomerular filtration depends on prostaglandin-mediated afferent vasodilatation and angiotensin II-mediated efferent vasoconstriction working in series. The NSAID blocks prostaglandin synthesis and removes afferent compensation; the ACE inhibitor removes efferent tone; the loop diuretic reduces intravascular volume. Each alone is tolerated; the three together collapse the transglomerular pressure gradient, and the vomiting has added a fourth hit. Creatinine rising from 1.8 to 3.6, urine output of 400 mL/day and a BP of 96/58 are the signature.

Hyperkalaemia (6.4 mmol/L) follows reduced distal delivery and reduced aldosterone effect during AKI, worsened by the ACE inhibitor, and is compounded here by the acidosis (bicarbonate 16 mmol/L), which shifts potassium out of cells.

Lactate 2.6 mmol/L in this context is mostly hypoperfusion, but metformin is an independent contributor and must not be left in place while the cause is sorted out.

Priority is hyperkalaemia with ECG changes, not the creatinine.

1. Stop the ibuprofen, ramipril and metformin now, and hold furosemide - continuing any of them worsens the physiology being corrected. Record the stops explicitly in the chart so they are not restarted by the next shift.
2. Attach cardiac monitoring and secure IV access. A potassium of 6.4 mmol/L with peaked T waves and a QRS of 110 ms is a cardiac emergency: the QRS widening indicates imminent risk of arrhythmia.
3. IV calcium gluconate for membrane stabilisation. This does not lower potassium; it protects the myocardium while the other measures take effect, and it must not be omitted because the potassium 'does not fall' afterwards.
4. IV insulin with glucose (for example 10 units of soluble insulin in 25 g glucose) to shift potassium intracellularly, with capillary glucose monitoring; a dextrose infusion is usually needed afterwards to prevent late hypoglycaemia. Nebulised salbutamol as an adjunct.
5. Treat the volume depletion cautiously. He needs volume, but he has an ejection fraction of 35%: give a small crystalloid challenge with close observation of BP, urine output, lung bases and saturations, rather than a large fixed bolus.
6. Consider sodium bicarbonate only if the acidosis is judged a major contributor; the evidence for benefit in this setting is weak. Potassium binder and urgent nephrology discussion/dialysis if potassium does not fall, or if urine output never recovers.
7. Recheck potassium, creatinine and glucose after therapy - a normal ECG does not mean a normal potassium, and a rebound is common.

Justification in one line: the ECG makes potassium the first-hour emergency; the lactate and metformin make drug withdrawal urgent; the creatinine must be re-checked after resuscitation, not treated with fluid alone.

Restart only when renal function has stabilised and potassium is below 5.0 mmol/L, on the following terms:

• Metformin: do not restart while eGFR remains below 30 mL/min/1.73 m^2. If eGFR recovers into the 30-45 band, do not simply resume 2 g a day - re-assess risk benefit and use a reduced dose; the drug should not be started at all in that band. If eGFR remains below 30, substitute a different agent for glycaemic control, taking hypoglycaemia risk into account at this age and renal function.
• Ramipril: restart at a lower dose (e.g. 2.5-5 mg), once creatinine has plateaued and potassium is below 5.0, remembering that a small creatinine rise on restarting is expected and acceptable; check potassium and creatinine at 1-2 weeks. His prognosis with HFrEF depends on the ACE inhibitor, so it should not be abandoned - it should be monitored.
• Furosemide: restart at the lowest dose that controls his weight and symptoms, with daily weights at home and clear instructions about what to do if his weight climbs.
• Atorvastatin: continue - it is not implicated.
• Ibuprofen: never again. Record it as an intolerance alert in his records and tell him explicitly that any pharmacy selling him this medicine risks his kidneys. For the knees: paracetamol up to 3 g a day, topical NSAID considered cautiously (systemic absorption is low but not zero in heart failure), physiotherapy, weight and walking aids.

Patient education: what each medicine is for; which ones to pause and for how long during any vomiting, diarrhoea or fever - the sick-day rule covering metformin, the ACE inhibitor and the diuretic, with a written card; who to call and how soon; and the instruction to tell every pharmacy and every doctor that he has kidney disease and heart failure and cannot take ibuprofen or similar painkillers.