The influence of hyperchloraemia on acid base interpretation in diabetic ketoacidosis.
OBJECTIVE
During the acute treatment of diabetic ketoacidosis we (a) determined the temporal incidence of hyperchloraemia, and (b) quantified the influence of hyperchloraemia on interpretation of common blood gas derived acid base parameters, namely base deficit and bicarbonate.


METHODS
Retrospective chart review in two regional paediatric intensive care units.


RESULTS
Stewart's physicochemical theory was used to develop regression equations quantifying the acidifying effect of hyperchloraemia on both base deficit and bicarbonate. These were then applied retrospectively to blood chemistry results from 18 children (median age 12.7 years, weight 43 kg) with diabetic ketoacidosis. Plasma ketonaemia was estimated using the albumin-corrected anion gap. The incidence of hyperchloraemia, as documented by a ratio of plasma chloride to sodium of greater than 0.79, increased from 6% at admission to 94% after 20 h of treatment. Correction for chloride produced a dramatic improvement in the relationship between changes in the anion gap vs. both base deficit (from R(2)=0.55 to R(2)=0.95) and bicarbonate (from R(2)=0.51 to R(2)=0.96) during treatment. After 20 h of treatment the mean base deficit had decreased from 24.7 mmol/l to 10.0 mmol/l however, the proportion that was due to hyperchloraemia increased from 2% to 98%.


CONCLUSIONS
It is now possible using a simple correction factor to quantify the confounding effect of hyperchloraemia on both base deficit and bicarbonate in diabetic ketoacidosis. This bedside tool may be a useful adjunct to guide therapeutic interventions.
Taylor
Dan
D
Paediatric Intensive Care Unit, Guy's Hospital, St Thomas Street, SE1 9RT, London, UK.
Durward
Andrew
A
Paediatric Intensive Care Unit, Guy's Hospital, St Thomas Street, SE1 9RT, London, UK.
Tibby
Shane M
SM
Paediatric Intensive Care Unit, Guy's Hospital, St Thomas Street, SE1 9RT, London, UK. shane.tibby@gstt.sthames.nhs.uk.
Thorburn
Kentigern
K
Paediatric Intensive Care Unit, Royal Liverpool Children's Hospital - Alder Hey, Eaton Road, L12 2AP, Liverpool, UK.
Holton
Fiona
F
Paediatric Intensive Care Unit, Guy's Hospital, St Thomas Street, SE1 9RT, London, UK.
Johnstone
Iain C
IC
Paediatric Intensive Care Unit, Guy's Hospital, St Thomas Street, SE1 9RT, London, UK.
Murdoch
Ian A
IA
Paediatric Intensive Care Unit, Guy's Hospital, St Thomas Street, SE1 9RT, London, UK.
D000137:Acid-Base Imbalance; D000208:Acute Disease; D002648:Child; D002712:Chlorides / Q000097:blood*; D016883:Diabetic Ketoacidosis / Q000097:blood* / Q000628:therapy; D005260:Female; D006801:Humans; D008297:Male; D012044:Regression Analysis; D012189:Retrospective Studies
D002712:Chlorides