Patient 1
A 77-year-old Caucasian female was admitted to the emergency department after two weeks of increasing abdominal pain associated with vomiting. Two days before admission, she developed psychomotor agitation. She had a past medical history of type 2 diabetes, arterial hypertension and cerebrovascular disease. She had had a stroke one month before with full recovery; at that time her creatinine was normal and she had been discharged from hospital with the following medications: metformin 3 g daily, perindopril 8 mg daily, and simvastatin 20 mg daily.
On admission examination revealed a Glasgow Coma Scale score of 12/15 (E4V3M5), blood pressure 136/87 mmHg, pulse 100 beats per minute, respiratory rate 20 breaths per minute and core body temperature 36.6°C. Despite being eupnoeic with oxygen saturation measured by pulse oximetry was 97% on room air, she presented with signs of poor perfusion.
Initial investigations revealed a creatinine of 6 mg/dL, sodium 142 mEq/L, potassium 4.7 mEq/L, chloride 103 mEq/L, glucose 216 mg/dL and C-reactive protein 3.14 mg/dl. Complete blood count (CBC) count showed 22.4 × 109/L white blood cells, with haemoglobin of 13.8 g/dL, and platelet count of 365 × 109/L. Arterial blood gas showed severe lactic acidosis (pH 6.87, PaCO2 8.2 mmHg, PaO2 146 mmHg, HCO3
- 1.4 mEq/L, blood lactate 16 mmol/L). Chest X-rays and ECG were normal at the time of her admission. Serum toxicological results, namely benzodiazepines, tricyclic antidepressants, opiates and barbiturates, were negative.
The patient was admitted to the intensive care unit (ICU) with the diagnosis of metformin related lactic acidosis. Continuous venovenous haemodialysis (CVVHD) was initiated, with 2 L/h of dyalisate flow and 35 ml/kg/h of hemofiltration using the solutions from Fresenius HF BIC, with 2 and 4 mEq/L of potassium as needed, using a high-flux dyalizer membrane (ultraflux AV 600s). Elective endotracheal intubation and mechanical ventilation was performed.
Four hours after the initiation of CVVHD significant improvement of acid-base status was observed and blood lactate level had halved (table
1). On the third day the patient was successfully weaned from the ventilator. On the 5th day a primary methicillin resistant Staphylococcus aureus bloodstream infection was diagnosed and the patient was started on vancomycin. The patient was discharged to the nephrology department ward on the seventh day.
Table 1
Patient 1 – Arterial blood gas results at admission, 4 h and 12 h after initiation of continuous venovenous hemodiafiltration
pH
| 6.8 | 7.434 | 7.4 |
PaCO
2
(mmHg)
| 8.2 | 15 | 22.9 |
PaO
2
(mmHg)
| 146 | 125 | 108.4 |
SaO
2
(%)
| 97.10 | 99.5 | 98.9 |
HCO
3
-
(mEq/L)
| 1.4 | 10.1 | 14.1 |
Lactate (mmol/L)
| 16 | 7.3 | 5 |
Full recovery of renal function was observed after 30 days and the patient was discharged from hospital on the 60th day medicated with insulin and glycazide.
Patient 2
A 69 year old male was admitted to the emergency department with confusion due to altered mental status. His past medical history included type 2 diabetes, stable angina and hypertension. There was no previous history of hospitalisations. His usual medications included metformin (4 g/day), isosorbide dinitrate (60 mg/day), glycazide (60 mg/day) and acetylsalicylic acid (150 mg/day).
On admission, the patient had extreme bradycardia with pulse rate 30 beats per minute, respiratory rate 28 breaths per minute, core body temperature 36.0°C and the blood pressure was immeasurable using the cuff method. There were no other significant findings on the physical examination. ECG showed complete atrio-ventricular block and the patient was immediately connected to an external pacemaker with significant haemodynamic improvement, blood pressure rising to 127/76 mmHg.
Initial investigations showed creatinine 2.2 mg/dL, sodium 135 mEq/L, potassium 3.4 mEq/L and glucose 436 mg/dL. Arterial blood gas showed severe lactic acidosis (pH 6.7, PaCO2 32.4 mmHg, PaO2 68.2 mmHg, HCO3
- 5.0 mEq/L, and lactates 18 mmol/L). Hemogram showed a normocytic, normochromic anaemia (haemoglobin 8 g/dL) and mild thrombocytopenia (platelets 130 × 109/L). Microscopic examination of the urine sediment showed the presence of glycosuria. Chest X-rays were normal. Serum toxicological results, namely for benzodiazepines, tricyclic antidepressants, opiates and barbiturates, were negative.
The patient started treatment with fluids, bicarbonate and insulin infusion since the admission diagnosis was ketoacidosis. During the procedure to implant a temporary pacemaker the patient suffered a respiratory-cardiac arrest followed by shock. He was then transferred to the ICU where he received vasopressor support with the diagnosis of metformin related lactic acidosis. Accordingly, CVVHD was initiated with 2 L/h of dyalisate flow and 35 ml/kg/h of hemofiltration using the solutions from Fresenius HF BIC, with 2 and 4 mEq/L of potassium as needed, using a high-flux dyalizer membrane (ultraflux AV 600s).
The patient stabilized after 4 hours of CVVHD with an improvement of acid-base status and a decreased lactate level (table
2). At the 12
th hour of ICU stay the patient no longer needed vasopressor support and he recovered stable sinus rhythm and, as a result, the pacemaker was removed. On the third day CVVHD was stopped with full recovery of renal function. On the same day, an early-onset ventilator associated pneumonia was diagnosed and the patient was put on empiric broad-spectrum antibiotic with piperacilin/tazobactam. Blood cultures, bronchial secretions and bronchoalveolar lavage were negative. The patient improved and was successfully weaned from the ventilator on the fifth day and was discharged from hospital on the seventh day.
Table 2
Patient 2 – Arterial blood gas results at admission, 4 h and 12 h after initiation of continuous venovenous hemodiafiltration
pH
| 6.7 | 7.34 | 7.43 |
PaCO
2
(mmHg)
| 32.4 | 23.1 | 29.8 |
PaO
2
(mmHg)
| 68.2 | 62 | 101.4 |
SaO
2
(%)
| 77.1 | 93.1 | 97.2 |
HCO
3
-
(mEq/L)
| 5 | 12 | 15 |
Lactate (mmol/L)
| 18 | 9.8 | 3.4 |