Metabolic acidosis in patients with severe sepsis and septic shock: a longitudinal quantitative study.
OBJECTIVE
To describe the composition of metabolic acidosis in patients with severe sepsis and septic shock at intensive care unit admission and throughout the first 5 days of intensive care unit stay.


METHODS
Prospective, observational study.


METHODS
Twelve-bed intensive care unit.


METHODS
Sixty patients with either severe sepsis or septic shock.


METHODS
None.


RESULTS
Data were collected until 5 days after intensive care unit admission. We studied the contribution of inorganic ion difference, lactate, albumin, phosphate, and strong ion gap to metabolic acidosis. At admission, standard base excess was -6.69 +/- 4.19 mEq/L in survivors vs. -11.63 +/- 4.87 mEq/L in nonsurvivors (p < .05); inorganic ion difference (mainly resulting from hyperchloremia) was responsible for a decrease in standard base excess by 5.64 +/- 4.96 mEq/L in survivors vs. 8.94 +/- 7.06 mEq/L in nonsurvivors (p < .05); strong ion gap was responsible for a decrease in standard base excess by 4.07 +/- 3.57 mEq/L in survivors vs. 4.92 +/- 5.55 mEq/L in nonsurvivors with a nonsignificant probability value; and lactate was responsible for a decrease in standard base excess to 1.34 +/- 2.07 mEq/L in survivors vs. 1.61 +/- 2.25 mEq/L in nonsurvivors with a nonsignificant probability value. Albumin had an important alkalinizing effect in both groups; phosphate had a minimal acid-base effect. Acidosis in survivors was corrected during the study period as a result of a decrease in lactate and strong ion gap levels, whereas nonsurvivors did not correct their metabolic acidosis. In addition to Acute Physiology and Chronic Health Evaluation II score and serum creatinine level,inorganic ion difference acidosis magnitude at intensive care unit admission was independently associated with a worse outcome.


CONCLUSIONS
Patients with severe sepsis and septic shock exhibit a complex metabolic acidosis at intensive care unit admission, caused predominantly by hyperchloremic acidosis,which was more pronounced in nonsurvivors. Acidosis resolution in survivors was attributable to a decrease in strong ion gap and lactate levels.
Noritomi
Danilo T
DT
Intensive Care Unit, Hospital Universitario, University of Sao Paulo, Sao Paulo, Brazil. dnoritomi@hotmail.com
Soriano
Francisco G
FG
Kellum
John A
JA
Cappi
Sylas B
SB
Biselli
Paolo J C
PJ
Libório
Alexandre B
AB
Park
Marcelo
M
D000136:Acid-Base Equilibrium / Q000502:physiology; D000138:Acidosis / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology*; D000328:Adult; D000368:Aged; D001639:Bicarbonates / Q000097:blood; D002118:Calcium / Q000097:blood; D002245:Carbon Dioxide / Q000097:blood; D002712:Chlorides / Q000097:blood; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007362:Intensive Care Units; D019344:Lactic Acid / Q000097:blood; D008137:Longitudinal Studies; D008274:Magnesium / Q000097:blood; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010710:Phosphates / Q000097:blood; D011379:Prognosis; D011446:Prospective Studies; D012709:Serum Albumin / Q000032:analysis; D012964:Sodium / Q000097:blood; D016019:Survival Analysis; D018746:Systemic Inflammatory Response Syndrome / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology*
D001639:Bicarbonates; D002712:Chlorides; D010710:Phosphates; D012709:Serum Albumin; D002245:Carbon Dioxide; D019344:Lactic Acid; D012964:Sodium; D008274:Magnesium; D010100:Oxygen; D002118:Calcium