The deteriorating patient — interpreting a multi-test result panel

1. The synthesis — prioritise by the threat to life (teaching approach). Run the six-step read on each value, but set the order by what can kill first, and read every result against this patient.^[1]

2. The potassium with a widened QRS. Intravenous calcium salts should be administered immediately in hyperkalaemic patients with ECG changes; calcium stabilises the cardiac cell membrane and is effective within 1–3 minutes, insulin and salbutamol shift potassium, only dialysis, potassium binders and loop diuretics remove it, and frequent re-evaluation of potassium is recommended.^[21]

3. The rising lactate. In the Surviving Sepsis Campaign database only lactate above 4 mmol per litre, with and without hypotension, was significantly associated with in-hospital mortality.^[1] Lactate elevation is commonly interpreted as a marker of tissue hypoxia, yet hyperlactataemia may occur despite adequate oxygen delivery.^[3]

4. The abdomen. In acute mesenteric ischaemia the pooled L-lactate sensitivity was 86 per cent with specificity 44 per cent; signs, symptoms and laboratory testing were insufficiently diagnostic, and only CT angiography had adequate accuracy to establish the diagnosis.^[22]

5. The gas. Calculate the serum anion gap as [Na+] − ([Cl−] + [HCO3−]); calculating it allows determination of coexisting acid-base processes, and comparing Δ anion gap with Δ HCO3− separates a simple anion gap acidosis from a superimposed non-gap acidosis or metabolic alkalosis.^[26]

6. The creatine kinase. Rhabdomyolysis is confirmed when the serum CK is above 1000 U/L or at least 5 times the upper limit of normal; it can cause volume depletion, metabolic and electrolyte abnormalities and acute kidney injury.^[27]

7. The troponin. The 99th percentile upper reference limit defines myocardial injury.^[24] Type 2 myocardial infarction occurs secondary to ischaemia from increased demand or decreased supply — sepsis accounted for 24 per cent in one survey — and needs a rise and fall of troponin with an imbalance unrelated to coronary thrombosis.^[23]

8. The lipase. Acute pancreatitis needs two of three criteria — upper abdominal pain, amylase or lipase above three times the upper limit of normal, or characteristic imaging.^[5]

9. The INR without warfarin. Sepsis-induced coagulopathy is present in 24 per cent of patients with sepsis and 66 per cent with septic shock, and its scoring systems weigh prothrombin time or INR, platelet count and fibrinogen changes.^[25]