Table 1.

Summary of quantitative acid–base studies in critically ill patients and the distribution of type of metabolic acidosis

Ref.	Patient population	Sample size	Metabolic acidosis	Unmeasured acids	Lactate	Chloride	Mixed
[30]	Pediatric ICU patients	540 samples (282 patients)	230 (45.5%) a44 – base deficit	120 (52%) – M	22 (9.6%) – M	88 (38.2%) – M	57 (25%) – M
[80]	Pediatric ICU post-cardiac surgery	150 samples (44 patients)	a24 – anion gap a57 – anion gap corrected	44	6	19	10
[15]	Pediatric ICU, patients only with acid–base measurements	255 patients	69 (27%)	55 (79.7%) – M	N/A	N/A	N/A
[79]	Pediatric ICU in shock	46 patients	42 (91%)	33 (72%) – M	39 (85%) – M	29 (63%) – M	N/A
[21]	Adult ICU with met acidosis	50 patients	50 (100%)	49 (98%) – M, T	31 (62%) – M, T	40 (80%) – M, T	N/A
[28]	Adult ICU with suspicion of lactic acidosis (highest lactate used)	851 patients	548 (64%) – T	204 (37%) – M	239 (44%) – M	105 (19%) – M	N/A

^aAuthors defined metabolic acidosis using three different techniques; measurement of other variables by quantitive approach. M, the percentage of the samples with a metabolic acidosis; T, the percentage of the 'total' number (n) of patients.