Lab Case 175 – Interpretation

40 year old female presents with haematemasis and a 2 day history of malaena.

-metabolic acidaemia –pH7.194 and HCO3 13 mmol/l

-expected pCO2 = (1.5XHCO3) +8 +/-2

= 28.5

-Anion gap =Na – (Cl+HCO3) = 21

  • Delta gap = AG-12/24-HCO3 =0.81

-severely low Hb of 48, and markedly high lactate 6.4.

Description – The VBG shows a severe metabolic acidaemia with inadequate respiratory compensation. The acidosis is a pure HAGMA, with a high lactate and severely low Hb.  The electrolytes of within normal limits, but the ionised Ca is on the lower end of normal. The glucose is normal.

Interpretation- the most common causes for a HAGMA are a lactic acidosis, toxins, ketoacidosis and renal failure. In the context of this case the HAGMA is likely due to the lactic acidosis secondary to haemorrhagic shock leading to poor tissue perfusion. Liver failure, thiamine deficiency and ethanol intoxication are type B causes for raised lactate and could be contributing to the raised lactate in this clinical context.

The low haemoglobin is likely acute given the patients short history of malaena and haematemasis as well as low BP and tachycardia. The cause of the haematemasis is most likely due to varices or PUD.

The actual pCO2 is higher than the expected, which means there is inadequate compensation or an underlying respiratory acidosis (secondary to aspiration or altered GCS in this case)

The ionised Ca is on the lower end of normal, which might imply the patient has already had a  blood transfusion.  It will be important to continue to monitor and replace the calcium during the resuscitation.

Management – this patient is critically unwell and requires immediate resuscitation and urgent referral to a gastroenterology team

Resuscitation – 2 large bore 16G IV lines

  • call for major haemorrhage pack and start O- blood transfusion while awaiting cross matched blood. Consider activating Major Haemorrhage Protocol and transfuse as per local protocol with packed cells, FFP and platelets.

-correct underlying bleeding diathesis

-consider intubation if airway not protected or considering insertion of a balloon tamponade eg Sengstaken-Blakemore tube. If intubation is done one needs to consider how to modify the RSI for an upper GI bleed eg use of prokinetics, double suction set up, use of video larygoscopy, Suction Assisted Laryngoscopy Airway Decontamination (SALAD), use of haemodynamically stable induction agents

-aim for MAP >60mmHg, urine output 0.5ml/kg/hr, normal GCS, temp>35, pH >7.2, BE<-6, Ca >1.1, plts >50, INR <1.5, Fibrinogen >1

Supportive Care – analgesia, avoiding hypothermia – warm to temp >35 degrees C, antibiotics for variceal bleeds – ceftriaxone 1g IVI, catheter to monitor u/o

Specific – Octreotide infusion to lower portal pressure until definitive haemostasis achieve

-PPI infusion for PUD

-Insertion of balloon tamponade tube if not responsive to resuscitation and medical management, continues to bleed and one does not have access to emergency endoscopy

Disposition – urgent gastroenterology  consult and endoscope for definitive management. Might need to consider interventional radiologist or GI surgeon.

 

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