Large infusion of crystalloids may induce acid-base alterations according to their strong ion difference ([SID]). We wanted to prove in vivo, at constant PCO2, that if the [SID] of the infused crystalloid is equal to baseline plasma bicarbonate, the arterial pH remains unchanged, if lower it decreases, and if higher it increases.In 12 pigs, anesthetized and mechanically ventilated at PCO2 a parts per thousand 40 mmHg, 2.2 l of crystalloids with a [SID] similar to (lactated Ringer's 28.3 mEq/l), lower than (normal saline 0 mEq/l), and greater than (rehydrating III 55 mEq/l) baseline bicarbonate (29.22 +/- A 2.72 mEq/l) were infused for 120 min in randomized sequence. Four hours of wash-out were allowed between the infusions. Every 30 min up to minute 120 we measured blood gases, plasma electrolytes, urinary volume, pH, and electrolytes. Albumin, hemoglobin, and phosphates were measured at time 0 and 120 min.Lactated Ringer's maintained arterial pH unchanged (from 7.47 +/- A 0.06 to 7.47 +/- A 0.03) despite a plasma dilution around 12%. Normal saline caused a reduction in pH (from 7.49 +/- A 0.03 to 7.42 +/- A 0.04) and rehydrating III induced an increase in pH (from 7.46 +/- A 0.05 to 7.49 +/- A 0.04). The kidney reacted to the infusion, minimizing the acid-base alterations, by increasing/decreasing the urinary anion gap, primarily by changing sodium and chloride concentrations. Lower urine volume after normal saline infusion was possibly due to its greater osmolarity and chloride concentration as compared to the other solutions.Results support the hypothesis that at constant PCO2, pH changes are predictable from the difference between the [SID] of the infused solution and baseline plasma bicarbonate concentration.

In vivo conditioning of acid-base equilibrium by crystalloid solutions: an experimental study on pigs

Protti, A;
2012-01-01

Abstract

Large infusion of crystalloids may induce acid-base alterations according to their strong ion difference ([SID]). We wanted to prove in vivo, at constant PCO2, that if the [SID] of the infused crystalloid is equal to baseline plasma bicarbonate, the arterial pH remains unchanged, if lower it decreases, and if higher it increases.In 12 pigs, anesthetized and mechanically ventilated at PCO2 a parts per thousand 40 mmHg, 2.2 l of crystalloids with a [SID] similar to (lactated Ringer's 28.3 mEq/l), lower than (normal saline 0 mEq/l), and greater than (rehydrating III 55 mEq/l) baseline bicarbonate (29.22 +/- A 2.72 mEq/l) were infused for 120 min in randomized sequence. Four hours of wash-out were allowed between the infusions. Every 30 min up to minute 120 we measured blood gases, plasma electrolytes, urinary volume, pH, and electrolytes. Albumin, hemoglobin, and phosphates were measured at time 0 and 120 min.Lactated Ringer's maintained arterial pH unchanged (from 7.47 +/- A 0.06 to 7.47 +/- A 0.03) despite a plasma dilution around 12%. Normal saline caused a reduction in pH (from 7.49 +/- A 0.03 to 7.42 +/- A 0.04) and rehydrating III induced an increase in pH (from 7.46 +/- A 0.05 to 7.49 +/- A 0.04). The kidney reacted to the infusion, minimizing the acid-base alterations, by increasing/decreasing the urinary anion gap, primarily by changing sodium and chloride concentrations. Lower urine volume after normal saline infusion was possibly due to its greater osmolarity and chloride concentration as compared to the other solutions.Results support the hypothesis that at constant PCO2, pH changes are predictable from the difference between the [SID] of the infused solution and baseline plasma bicarbonate concentration.
2012
Crystalloid solutions
Acid-base equilibrium
Stewart's approach
Volume resuscitation
Animal study
Acid-Base Equilibrium
Analysis of Variance
Animals
Bicarbonates
Capnography
Crystalloid Solutions
Hydrogen-Ion Concentration
Isotonic Solutions
Linear Models
Random Allocation
Ringer's Lactate
Sodium Chloride
Swine
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11699/61560
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