A 33 year old female presented with high fever and abdominal pain. She 
has gram negative bacteraemia and septic shock. The following are data 
from blood gas analysis. ·

Parameter

Patient Value

Normal Range

FiO2

0.3

pH

7.43

7.35 – 7.45

PaCO2

23* mmHg (3.0 kPa)

35 – 45 (4.6 – 6.0)

PaO2

107 mmHg (14 kPa)

HCO3

15* mmHg

22 – 26

Standard base excess

-8.6* mmol/l

-2 – +2

Sodium

147* mmol/l

135 – 145

Potassium

6.7* mmol/l

3.2 – 4.5

Chloride

95* mmol/l

100 – 110

Lactate

23.0* mmol/l

< 2

a} List the acid-base abnormalities

b)  What are the causes of elevated plasma lactate in sepsis? 

c)  Name 3 drugs which result in plasma hyperlactaemia

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College Answer

a} List the acid-base abnormalities

High anion gap metabolic acidosis with raised lactate Metabolic alkalosis (Delta BE <Delta AG) Respiratory alkalosis

b)  What are the causes of elevated plasma lactate in sepsis? 
1)  Circulatory failure due to hypotension and hypoxia
2)  Microvascular shunting and mitochondrial failure (cytopathic hypoxia)
3)  Use of adrenaline as an inotrope
4)  Inhibition of pyruvate dehydrogenase (PDH) by endotoxin.

c)  Name 3 drugs which result in plasma hyperlactaemia
-     Catecholamines
-    Metformin I Phenformin 
-      Alcohols
-    Cyanide, nitroprusside
-     Salicylates

Discussion

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References

Grubbs, Robert D., and Michael E. Maguire. "Magnesium as a regulatory cation: criteria and evaluation." Magnesium 6.3 (1986): 113-127.

 

Martin, Kevin J., Esther A. González, and Eduardo Slatopolsky. "Clinical consequences and management of hypomagnesemia." Journal of the American Society of Nephrology 20.11 (2009): 2291-2295.

 

Chakraborti, Sajal, et al. "Protective role of magnesium in cardiovascular diseases: a review." Molecular and cellular biochemistry 238.1-2 (2002): 163-179.