title: A physicochemical model of crystalloid infusion on acid-base status.
abstract: The objective of this study is to develop a physicochemical model of the projected change in standard base excess (SBE) consequent to the infused volume of crystalloid solutions in common use. A clinical simulation of modeled acid-base and fluid compartment parameters was conducted in a 70-kg test participant at standard physiologic state: pH =7.40, partial pressure of carbon dioxide (PCO2) = 40 mm Hg, Henderson-Hasselbalch actual bicarbonate ([HCO3]HH) = 24.5 mEq/L, strong ion difference (SID) = 38.9 mEq/L, albumin = 4.40 g/dL, inorganic phosphate = 1.16 mmol/L, citrate total = 0.135 mmol/L, and SBE =0.1 mEq/L. Simulations of multiple, sequential crystalloid infusions up to 10 L were conducted of normal saline (SID = 0), lactated Ringer's (SID = 28), plasmalyte 148 (SID = 50), one-half normal saline þ 75 mEq/L sodium bicarbonate (NaHCO3; SID = 75), 0.15 mol/L NaHCO3 (SID = 150), and a hypothetical crystalloid solution whose SID = 24.5 mEq/L, respectively. Simulations were based on theoretical completion of steady-state equilibrium and PCO2 was fixed at 40 mm Hg to assess nonrespiratory acid-base effects. A crystalloid SID equivalent to standard state actual bicarbonate (24.5 mEq/L) results in a neutral metabolic acid-base status for infusions up to 10 L. The 5 study solutions exhibited curvilinear relationships between SBE and crystalloid infusion volume in liters. Solutions whose SID was greater than 24.5 mEq/L demonstrated a progressive metabolic alkalosis and less, a progressive metabolic acidosis. In a human model system, the effects of crystalloid infusion on SBE are a function of the crystalloid and plasma SID, volume infused, and nonvolatile plasma weak acid changes. A projection of the impact of a unit volume of various isotonic crystalloid solutions on SBE is presented. The model's validation, applications, and limitations are examined.
authors.affiliation: Alta Bates Summit Medical Center, Oakland, CA, USA. edofiron@gmail.com
authors.forename: Edward M
authors.initials: EM
authors.lastname: Omron
authors.forename: Rodney M
authors.initials: RM
authors.lastname: Omron
mesh_terms: D000136:Acid-Base Equilibrium / Q000187:drug effects*; D000138:Acidosis / Q000139:chemically induced; D001639:Bicarbonates / Q000008:administration & dosage / Q000494:pharmacology; D001825:Body Fluid Compartments / Q000502:physiology; D002245:Carbon Dioxide; D000077324:Crystalloid Solutions; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007552:Isotonic Solutions / Q000008:administration & dosage* / Q000009:adverse effects / Q000494:pharmacology; D008954:Models, Biological; D010313:Partial Pressure; D015532:Rehydration Solutions / Q000008:administration & dosage* / Q000009:adverse effects / Q000494:pharmacology; D000077325:Ringer's Lactate; D012965:Sodium Chloride / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D001639:Bicarbonates; D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D015532:Rehydration Solutions; D000077325:Ringer's Lactate; D002245:Carbon Dioxide; D012965:Sodium Chloride