A 37-year-old previously healthy man was admitted to your ICU five days ago after a motor vehicle crash with chest and abdominal injuries. He is currently intubated and ventilated, with FIO2 1.0 and PEEP 10 cmH2O. He is deeply sedated and on noradrenaline and adrenaline infusions at 10mcg/min each. He has become oliguric.
His blood biochemistry, haematology and arterial blood gases are as follows
Venous Biochemistry
Test |
Value |
Normal Adult Range |
Sodium |
138 mmol/L |
135 – 145 |
Potassium |
7.1 mmol/L* |
3.5 – 4.5 |
Chloride |
104 mmol/L |
95 – 105 |
Urea |
27 mmol/L* |
2.9 – 8.2 |
Creatinine |
260 μmol/L* |
70 – 120 |
Haematology
Test |
Value |
Normal Adult Range |
Haemoglobin |
120 G/L* |
135 -180 |
White Blood Cells |
12.8 x 109/L* |
4.0 -11.0 |
Platelets |
42 x 109/L* |
140 - 400 |
Arterial Blood Gases
Test |
Value |
Normal Adult Range |
pH |
7.01* |
7.35 – 7.45 |
PCO2 |
45 mmHg (6 kPa) |
35 – 45 (4.6 – 6.0) |
PO2 |
70 mm Hg (9.3 kPa)* |
|
Bicarbonate |
11 mmol/L* |
22 - 26 |
Base Excess |
-19 mmol/L* |
-2.0 – + 2.0 |
Glucose |
7.5 mmol/L* |
4 – 6 |
Lactate |
13 mmol/L* |
< 2.0 |
a) Summarise the findings of the blood tests.
b) List the likely causes of the raised lactate.
c) Briefly outline your management priorities for this man.
a)
b)
c)
Management Priorities should encompass both immediate resuscitation and investigation for the cause of the abnormalities.
Respiratory:
Clinical examination and CXR looking for cause of hypoxia – consider lung contusion, haemothorax/pneumothorax with shock, ARDS secondary to other process. Institute ARDS ventilation strategy if appropriate.
Cardiovascular:
Clinical examination and further investigations to determine cause of inotrope and vasopressor requirement. Consider ECHO. Fluid resuscitation if hypovolaemia suggested by examination /ECHO findings.
Cease adrenaline if possible.
Renal
Emergency management of hyperkalaemia – calcium, bicarbonate, dextrose, insulin, followed by institution of renal replacement therapy.
Examination and investigation for cause of deterioration:
Abdominal examination and measurement of intrabadominal pressures Examination for potential sources of infection, including GI, lines, ventilator acquired
pneumonia, wounds, urine. Consider empirical antibiotic treatment if thought to be septic aetiology.
Serum lipase, troponin, CK, blood cultures.
Examination to exclude limb compartments, rhabdomyolysis.
Imaging as suggested by results of examination – may require abdominal/thoracic CT scan, renal USS if anuric, angiography/endoscopy if evidence of ongoing bleeding.
Let us dissect these results systematically.
Thus, in summary there is both a respiratory acidosis and a HAGMA, which is only partially related to lactate.
On top of that, the patient is severy hypoxic, thrombocytopenic, hyperkalemic, and in renal failure with uremia.
The likely causes of raised lactate are
In general, the causes of lactic acidosis are discussed at great length elsewhere.
The management priorities - if one were going to approach this with some sort of system - would resemble the following list:
Airway
Ventilation
Circulation
Shock state needs to be investigated; potential causes include
A TTE can rule out many of these causes.
Thereafter, it would be helpful to wean off adrenaline, and if need be change over to a non-catecholamine inotrope (eg. milrinone).
Sedation and paralysis
Electrolytes
Fluid balance
Abdominal injuries
Haematological disturbances
Infectious complications
Luft FC. Lactic acidosis update for critical care clinicians. J Am Soc Nephrol 2001 Feb; 12 Suppl 17 S15-9.
Ohs manual – Chapter 15 by D J (Jamie) Cooper and Alistair D Nichol, titled “Lactic acidosis” (pp. 145)
Cohen RD, Woods HF. Lactic acidosis revisited. Diabetes 1983; 32: 181–91.
Lange, H., and R. Jäckel. "Usefulness of plasma lactate concentration in the diagnosis of acute abdominal disease." The European journal of surgery= Acta chirurgica 160.6-7 (1994): 381.
WEIL, MAX HARRY, and ABDELMONEN A. AFIFI. "Experimental and clinical studies on lactate and pyruvate as indicators of the severity of acute circulatory failure (shock)." Circulation 41.6 (1970): 989-1001.