A 32 year old male presents to ED after cutting his right cubital fossa in a suicide attempt. According to the paramedics there was a large amount of blood on scene.
VBG on arrival:
pH 6.98 Na 141 mmol/l
pCO2 82 mmHg K 4.2 mmol/l
HCO3 15 mmHg Cl 105 mmol/l
B/E – 20 Cr 173 umol/l
HB 126 Lactate 15 mmol/l
- Describe and interpret the VBG
- List immediate management priorities
Answer
Severe acidaemia
Mixed metabolic and respiratory acidosis.
AG = Na- (Cl+HCO3) = 21
Markedly elevated lactate, with a raised chloride, normal Hb
The above VBG shows a mixed respiratory and high anion metabolic acidosis. In this clinical context the HAGMA is most likely due to hypovolemic shock leading to a lactic acidosis, however toxins need to be excluded especially toxic alcohols that lead to a severely raised lactate. Hypoperfusion would lead to prerenal failure accounting for the AKI, but toxic alcohols can also be a cause of AKI. Further biochemical markers that would confirm toxic alcohol ingestion would be a raised osmolar gap.
The respiratory acidosis would likely be due to hypoperfusion of the brain leading to decreased GCS and airway obstruction leading to hypoventilation
The normal Hb in the context of haemorrhagic shock is a result of haemodilution.
Immediate Management priorities would include:
- Direct pressure to wound to stop bleeding
- Obtain 2 large IV cannulation, sending blood for X match, ROTEM and activation of major haemorrhage protocol, with urgent O negative blood to start resuscitation
- Assess A and B and need for intubation in context of high CO2. Patient requires more resuscitation before intubation, with correction of hypovolaemia prior to intubation. Modified RSI with continuous bagging required to avoid worsening acidosis
- Continuous monitoring, arterial line and IDC to monitor u/o. Repeat VBG and ROTEM to assess response to treatment and need for further blood products
- Look for and treat other possible causes of severe lactic acidosis ie toxic alcohols