I agree; if you do the H-H equation, the calculated bicarb should be 7. I agree that the only interpretation I can think of is that this is a lab error. However, a few days earlier he had a similar gas where the measured bicarb was above 24 and the calculated was again low. I wonder what factors would contribute to the machione measuring this incorrectly. I think that the way they measure bicarb in a chem-7 is to add a strong acid thuis converting the bicarb to CO2 and water and then the machine measures the CO2, but this would give you an error in the other direction... BTW, a good online calulator for hend-hasselbach equation: http://medcalc3000.com/HendersonHasselbach.htm
That's interesting, because the patient was indeed on heparin. Furthermore, when the gas was repeat the pH was about 7.32 so maybe that one was drawn from the peripheral line...
Just a clarification - it's the quantity of heparin(in the syringe) and blood sample drawn that could alter the ABG. Heparinisation of the patient should not make any difference.
I agree; if you do the H-H equation, the calculated bicarb should be 7. I agree that the only interpretation I can think of is that this is a lab error. However, a few days earlier he had a similar gas where the measured bicarb was above 24 and the calculated was again low.
ReplyDeleteI wonder what factors would contribute to the machione measuring this incorrectly. I think that the way they measure bicarb in a chem-7 is to add a strong acid thuis converting the bicarb to CO2 and water and then the machine measures the CO2, but this would give you an error in the other direction...
BTW, a good online calulator for hend-hasselbach equation: http://medcalc3000.com/HendersonHasselbach.htm
BTW, no protein was done, but his serum albumin was less than 1.
ReplyDeleteI agree with Doug. The low albumin will lower your AG but will not explain the incongruencies.
ReplyDeleteToo much heparin in the ABG sample could falsely make the sample acidotic
ReplyDeleteThat's interesting, because the patient was indeed on heparin. Furthermore, when the gas was repeat the pH was about 7.32 so maybe that one was drawn from the peripheral line...
ReplyDeleteJust a clarification - it's the quantity of heparin(in the syringe) and blood sample drawn that could alter the ABG. Heparinisation of the patient should not make any difference.
ReplyDelete