Comparison of three strong ion models used for quantifying the acid-base status of human plasma with special emphasis on the plasma weak acids

2005 ◽  
Vol 98 (6) ◽  
pp. 2119-2125 ◽  
Author(s):  
Chris M. Anstey
Keyword(s):  
Metabolic Stress ◽  
Ordinary Least Squares ◽  
Weak Acid ◽  
Model Parameters ◽  
Strong Ion Difference ◽  
Least Squares Regression ◽  
Weak Acids ◽  
Acid Base ◽  
Ph Titration ◽  
Significant Difference

Currently, three strong ion models exist for the determination of plasma pH. Mathematically, they vary in their treatment of weak acids, and this study was designed to determine whether any significant differences exist in the simulated performance of these models. The models were subjected to a “metabolic” stress either in the form of variable strong ion difference and fixed weak acid effect, or vice versa, and compared over the range 25 ≤ Pco2 ≤ 135 Torr. The predictive equations for each model were iteratively solved for pH at each Pco2 step, and the results were plotted as a series of log(Pco2)-pH titration curves. The results were analyzed for linearity by using ordinary least squares regression and for collinearity by using correlation. In every case, the results revealed a linear relationship between log(Pco2) and pH over the range 6.8 ≤ pH ≤ 7.8, and no significant difference between the curve predictions under metabolic stress. The curves were statistically collinear. Ultimately, their clinical utility will be determined both by acceptance of the strong ion framework for describing acid-base physiology and by the ease of measurement of the independent model parameters.

Plasma-Lyte 148 vs. Hartmann’s solution for cardiopulmonary bypass pump prime: a prospective double-blind randomized trial

Perfusion ◽  
2017 ◽  
Vol 33 (4) ◽  
pp. 310-319 ◽  
Author(s):  
Laurence Weinberg ◽  
Elizabeth Chiam ◽  
James Hooper ◽  
Frank Liskaser ◽  
Angela Kim Hawkins ◽  
...  
Keyword(s):  
Cardiopulmonary Bypass ◽  
Randomized Trial ◽  
Repeated Measures ◽  
Hospital Length ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Acid Base ◽  
Double Blind ◽  
Elective Cardiac Surgery ◽  
Significant Difference

Background: The mechanisms of acid-base changes during cardiopulmonary bypass (CPB) remain unclear. We tested the hypothesis that, when used as CPB pump prime solutions, Plasma-Lyte 148 (PL) and Hartmann’s solution (HS) have differential mechanisms of action in their contribution to acid-base changes. Methods: We performed a prospective, double-blind, randomized trial in adult patients undergoing elective cardiac surgery with CPB. Participants received a CPB prime solution of 2000 mL, with either PL or HS. The primary endpoint was the standard base excess (SBE) value measured at 60 minutes after full CPB flows (SBE60min). Secondary outcomes included changes in SBE, pH, chloride, sodium, lactate, gluconate, acetate, strong ion difference and strong ion gap at two (T2min), five (T5min), ten (T10min), thirty (T30min) and sixty (T60min) minutes on CPB. The primary outcome was measured using a two-tailed Welch’s t-test. Repeated measures ANOVA was used to test for differences between time points. Results: Twenty-five participants were randomized to PL and 25 to HS. Baseline characteristics, EURO and APACHE scores, biochemistry, hematology and volumes of cardioplegia were similar. Mean (SD) SBE at T60min was -1.3 (1.4) in the PL group and -0.1 (2.7) in the HS group; p=0.55. No significant differences in SBE between the groups was observed during the first 60 minutes (p=0.48). During CPB, there was hyperacetatemia and hypergluconatemia in the PL group and hyperlactatemia and hyperchloremia in the HS group. No significant difference between the groups in plasma bicarbonate levels and total weak acid levels were found. Complications and intensive care unit and hospital length of stays were similar. Conclusions: During CPB, PL and HS did not cause a significant metabolic acidosis. There was hyperacetatemia and hypergluconatemia with PL and hyperchloremia and hyperlactatemia with HS. These physiochemical effects appear clinically innocuous.

Acid–base regulations a comparison of quantitative methods

1994 ◽  
Vol 72 (7) ◽  
pp. 818-826 ◽  
Author(s):  
John M. Kowalchuk ◽  
Barry W. Scheuermann
Keyword(s):  
Quantitative Methods ◽  
Linear Regression Analysis ◽  
Venous Blood ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Weak Acids ◽  
Acid Base ◽  
Ramp Exercise ◽  
The Difference ◽  
Biological Solutions

The [H+] and [HCO3−] of biological solutions is determined by the [Formula: see text], the concentration of strong ions (mainly Na+, K+, Ca2+, Cl−, lactate−), and the concentration of weak acids (mainly proteins, phosphates). Two mathematical models are available that use a quantitative approach to describe the acid–base behaviour of plasma, but which differ in their treatment of the weak acid component: Stewart model (using [Formula: see text], strong ion difference (SID = [Na+ + K+ + Ca2+] − [Cl− + lactate−]) and [protein]TOT); Fencl model (using [Formula: see text], SID, [albumin], and [Pi]TOT). The present study compared measured and estimated [H+] and [HCO3−] in whole-blood samples collected from eight subjects during two double-ramp exercise protocols to the limit of tolerance to assess the accuracy with which each of the quantitative models predicts measured values. Arterialized-venous blood was analyzed for [H+], [Formula: see text], [protein]TOT, [albumin], [Pi]TOT, and SID (= [Na+ + K+ + Ca2+] − [Cl− + lactate−]), and these independent variables were then substituted into the appropriate mathematical model to estimate [H+] and [HCO3−]. Analysis showed that the [H+] and [HCO3−] estimated using either model provided a good estimate of the [H+] (Stewart model, r = 0.81; Fencl model, r = 0.81) and [HCO3−] (Stewart model, r = 0.93; Fencl model, r = 0.93) measured in plasma; linear regression analysis demonstrated that the slopes and intercepts for each of die relationships were not different (p > 0.05) from the line of identity. Differences between estimated and measured values were small, averaging < 3 nmol∙L−1 for [H+] and < 2 mmol∙L−1 for [HCO3−]. However, in the case of plasma [H+], the difference between estimated and measured values became skewed (i.e., [H+]M < [H+]Est) above [H+]M ≈ 55 nmol∙L−1, or at [SID] ≤ 35 mequiv.∙L−1. Reasons for the difference between measured and estimated values are discussed, with attention given to the [SID] and weak acid components.Key words: quantitative acid–base chemistry, strong ion difference, weak acids, strong ions, lactate, hydrogen ion, bicarbonate.

Total weak acid concentration and effective dissociation constant of nonvolatile buffers in human plasma

2001 ◽  
Vol 91 (3) ◽  
pp. 1364-1371 ◽  
Author(s):  
Peter D. Constable
Keyword(s):  
Dissociation Constant ◽  
Human Plasma ◽  
Total Concentration ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Acid Base ◽  
Horse Plasma ◽  
Using Data ◽  
Species Specific

The strong ion approach provides a quantitative physicochemical method for describing the mechanism for an acid-base disturbance. The approach requires species-specific values for the total concentration of plasma nonvolatile buffers (Atot) and the effective dissociation constant for plasma nonvolatile buffers ( K a), but these values have not been determined for human plasma. Accordingly, the purpose of this study was to calculate accurate Atot and K a values using data obtained from in vitro strong ion titration and CO2tonometry. The calculated values for Atot (24.1 mmol/l) and K a (1.05 × 10−7) were significantly ( P < 0.05) different from the experimentally determined values for horse plasma and differed from the empirically assumed values for human plasma (Atot = 19.0 meq/l and K a = 3.0 × 10−7). The derivatives of pH with respect to the three independent variables [strong ion difference (SID), Pco 2, and Atot] of the strong ion approach were calculated as follows: [Formula: see text] [Formula: see text], [Formula: see text]where S is solubility of CO2 in plasma. The derivatives provide a useful method for calculating the effect of independent changes in SID+, Pco 2, and Atot on plasma pH. The calculated values for Atot and K a should facilitate application of the strong ion approach to acid-base disturbances in humans.

A simplified strong ion model for acid-base equilibria: application to horse plasma

1997 ◽  
Vol 83 (1) ◽  
pp. 297-311 ◽  
Author(s):  
Peter D. Constable
Keyword(s):  
Human Plasma ◽  
Practical Method ◽  
Published Data ◽  
Strong Ion Difference ◽  
Weak Acids ◽  
Acid Base ◽  
Plasma Protein Concentration ◽  
Horse Plasma ◽  
Hasselbalch Equation

Constable, Peter D. A simplified strong ion model for acid-base equilibria: application to horse plasma. J. Appl. Physiol. 83(1): 297–311, 1997.—The Henderson-Hasselbalch equation and Stewart’s strong ion model are currently used to describe mammalian acid-base equilibria. Anomalies exist when the Henderson-Hasselbalch equation is applied to plasma, whereas the strong ion model does not provide a practical method for determining the total plasma concentration of nonvolatile weak acids ([Atot]) and the effective dissociation constant for plasma weak acids ( K a). A simplified strong ion model, which was developed from the assumption that plasma ions act as strong ions, volatile buffer ions ([Formula: see text]), or nonvolatile buffer ions, indicates that plasma pH is determined by five independent variables:[Formula: see text], strong ion difference, concentration of individual nonvolatile plasma buffers (albumin, globulin, and phosphate), ionic strength, and temperature. The simplified strong ion model conveys on a fundamental level the mechanism for change in acid-base status, explains many of the anomalies when the Henderson-Hasselbalch equation is applied to plasma, is conceptually and algebraically simpler than Stewart’s strong ion model, and provides a practical in vitro method for determining [Atot] and K a of plasma. Application of the simplified strong ion model to CO2-tonometered horse plasma produced values for [Atot] (15.0 ± 3.1 meq/l) and K a(2.22 ± 0.32 × 10−7 eq/l) that were significantly different from the values commonly assumed for human plasma ([Atot] = 20.0 meq/l, K a = 3.0 × 10−7 eq/l). Moreover, application of the experimentally determined values for [Atot] and K a to published data for the horse (known [Formula: see text], strong ion difference, and plasma protein concentration) predicted plasma pH more accurately than the values for [Atot] and K a commonly assumed for human plasma. Species-specific values for [Atot] and K a should be experimentally determined when the simplified strong ion model (or strong ion model) is used to describe acid-base equilibria.

scholarly journals Construction of A New Dose–Response Model for Staphylococcus aureus Considering Growth and Decay Kinetics on Skin

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 253 ◽  
Author(s):  
Esfahanian ◽  
Adhikari ◽  
Dolan ◽  
Mitchell
Keyword(s):  
Staphylococcus Aureus ◽  
Dose Response ◽  
Sensitivity Coefficient ◽  
Ordinary Least Squares ◽  
Exposure Dose ◽  
Human Infection ◽  
Model Parameters ◽  
Response Model ◽  
Least Squares Regression ◽  
Decay Kinetics

. In order to determine the relationship between an exposure dose of Staphylococcus aureus (S. aureus) on the skin and the risk of infection, an understanding of the bacterial growth and decay kinetics is very important. Models are essential tools for understanding and predicting bacterial kinetics and are necessary to predict the dose of organisms post-exposure that results in a skin infection. One of the challenges in modeling bacterial kinetics is the estimation of model parameters, which can be addressed using an inverse problem approach. The objective of this study is to construct a microbial kinetic model of S. aureus on human skin and use the model to predict concentrations of S. aureus that result in human infection. In order to model the growth and decay of S. aureus on skin, a Gompertz inactivation model was coupled with a Gompertz growth model. A series of analyses, including ordinary least squares regression, scaled sensitivity coefficient analysis, residual analysis, and parameter correlation analysis were conducted to estimate the parameters and to describe the model uncertainty. Based on these analyses, the proposed model parameters were estimated with high accuracy. The model was then used to develop a new dose-response model for S. aureus using the exponential dose–response model. The new S. aureus model has an optimized k parameter equivalent to 8.05 × 10−8 with 95th percentile confidence intervals between 6.46 × 10−8 and 1.00 × 10−7.

General Slowing in Language Impairment

2001 ◽  
Vol 44 (2) ◽  
pp. 446-461 ◽  
Author(s):  
Jennifer Windsor ◽  
Rochelle L. Milbrath ◽  
Edward J. Carney ◽  
Susan E. Rakowski
Keyword(s):  
Word Recognition ◽  
Hierarchical Linear Modeling ◽  
Language Impairment ◽  
Ordinary Least Squares ◽  
Random Coefficients ◽  
Least Squares Regression ◽  
Linear Modeling ◽  
Data Set ◽  
Significant Difference ◽  
General Slowing

Although the general slowing hypothesis of language impairment (LI) is well established, the conventional method to test the hypothesis is controversial. This paper compares the usual method, ordinary least squares regression (OLS), with another method, hierarchical linear modeling with random coefficients (HLM). The analyses used available response time (RT) data from studies of perceptual-motor, cognitive, and language skills of LI and chronological-age-matched (CA) groups. The data set included RT measures from 25 studies investigating 20 different tasks (e.g., auditory detection, mental rotation, and word recognition tasks). OLS and HLM analyses of the RT data yielded very different results. OLS supported general slowing for the LI groups, and indicated that they were significantly slower than CA groups across studies by an overall estimate of 10%. HLM indicated a larger average extent of LI slowing (18%). However, the variability around this average was much greater than that yielded by OLS, and the extent of slowing was not statistically significant. Importantly, HLM showed a significant difference in the RT relation between LI and CA groups across studies, indicating that study-specific slowing, rather than general slowing across studies, was present. A separate HLM analysis of two types of language tasks, picture naming and word recognition, was performed. Although the extent of slowing was equivalent across these tasks, the slowing was minimal (2%) and not significant. Methodological limitations of each analysis to assess general slowing are highlighted.

scholarly journals Effect of Interest Rate Determinants on the Aggregate Performance of Deposit Money Banks in Nigeria’s Banking Sector

2018 ◽  
Vol 6 (6) ◽  
pp. 29
Author(s):  
Oluwarotimi Ayokunnu Owolabi ◽  
Ibukun Omoshola Fayemi
Keyword(s):  
Monetary Policy ◽  
Interest Rate ◽  
Least Squares ◽  
Ordinary Least Squares ◽  
T Test ◽  
Bank Performance ◽  
Least Squares Regression ◽  
Ordinary Least Squares Regression ◽  
Paired Samples ◽  
Significant Difference

This study explores the effect of selected interest rate determinants and their significance on the performance of Deposit money banks in Nigeria, and whether the determinants are significantly different between High performance and low performance periods, over the period of 1998 to 2015. Multivariate ordinary least squares regression and paired samples t-test were employed in performing the study. The findings of Multivariate ordinary least squares regression revealed that exchange rate has a positive and statistically significant effect on deposit money bank performance, Monetary policy rate and Credit Risk have a negative and statistically significant effect on deposit money bank performance , while Inflation rate and savings deposit rate have a statistically insignificant effect on deposit money bank performance. Results of paired samples t-test revealed significant difference in means of determinants. The study recommends Naira devaluation and reduction of monetary policy rate amongst other recommendations to boost bank performance in Nigeria

scholarly journals Hypoproteinemia, strong-ion difference, and acid-base status in critically ill patients

1998 ◽  
Vol 84 (5) ◽  
pp. 1740-1748 ◽  
Author(s):  
Peter Wilkes
Keyword(s):  
Total Protein ◽  
Protein Concentration ◽  
Total Concentration ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Acid Base ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Acid Base Status ◽  
The Relationship

The present study was a prospective, nonrandomized, observational examination of the relationship among hypoproteinemia and electrolyte and acid-base status in a critical care population of patients. A total of 219 arterial blood samples reviewed from 91 patients was analyzed for arterial blood gas, electrolytes, lactate, and total protein. Plasma strong-ion difference ([SID]) was calculated from [Na+] + [K+] − [Cl−] − [La−]. Total protein concentration was used to derive the total concentration of weak acid ([A]tot). [A]tot encompassed a range of 18.7 to 9.0 meq/l, whereas [SID] varied from 48.1 to 26.6 meq/l and was directly correlated with [A]tot. The decline in [SID] was primarily attributable to an increase in [Cl−]. A direct correlation was also noted between[Formula: see text] and [SID], but not between [Formula: see text] and [A]tot. The decrease in [SID] and [Formula: see text] was such that neither [H+] nor [[Formula: see text]] changed significantly with [A]tot.

Hematological and acid-base changes in men during prolonged exercise with and without sodium-lactate infusion

2005 ◽  
Vol 98 (3) ◽  
pp. 856-865 ◽  
Author(s):  
Benjamin F. Miller ◽  
Michael I. Lindinger ◽  
Jill A. Fattor ◽  
Kevin A. Jacobs ◽  
Paul J. LeBlanc ◽  
...  
Keyword(s):  
Metabolic Regulation ◽  
Prolonged Exercise ◽  
Lactate Concentration ◽  
Sodium Lactate ◽  
Weak Acid ◽  
Moderate Intensity ◽  
Strong Ion Difference ◽  
Acid Base ◽  
Plasma Lactate Concentration ◽  
Lactate Infusion

An emerging technique used for the study of metabolic regulation is the elevation of lactate concentration with a sodium-lactate infusion, the lactate clamp (LC). However, hematological and acid-base properties affected by the infusion of hypertonic solutions containing the osmotically active strong ions sodium (Na+) and lactate (Lac−) are a concern for clinical and research applications of LC. In the present study, we characterized the hematological and plasma acid-base changes during rest and prolonged, light- to moderate-intensity (55% V̇o2 peak) exercise with and without LC. During the control (Con) trial, subjects were administered an isotonic, isovolumetric saline infusion. During LC, plasma lactate concentration ([Lac−]) was elevated to 4 meq/l during rest and to 4–7 meq/l during exercise. During LC at rest, there were rapid and transient changes in plasma, erythrocyte, and blood volumes. LC resulted in decreased plasma [H+] (from 39.6 to 29.6 neq/l) at the end of exercise while plasma [HCO3−] increased from 26 to 32.9 meq/l. Increased plasma strong ion difference [SID], due to increased [Na+], was the primary contributor to decreased [H+] and increased [HCO3−]. A decrease in plasma total weak acid concentration also contributed to these changes, whereas Pco2 contributed little. The infusion of hypertonic LC caused only minor volume, acid-base, and CO2 storage responses. We conclude that an LC infusion is appropriate for studies of metabolic regulation.

scholarly journals Acid-Base Balance in Callinectes Sapidus During Acclimation from High to Low Salinity

1982 ◽  
Vol 101 (1) ◽  
pp. 255-264 ◽  
Author(s):  
RAYMOND P. HENRY ◽  
JAMES N. CAMERON
Keyword(s):  
Carbonic Anhydrase ◽  
Blue Crab ◽  
Callinectes Sapidus ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Ion Regulation ◽  
Low Salinity ◽  
Base Balance

When transferred from 865 to 250 m-osmol salinity, the blue crab C. sapidus maintains its blood Na+ and Cl− concentrations significantly above those in the medium. When branchial carbonic anhydrase is inhibited by acetazolamide, ion regulation fails and the animals do not survive the transfer. An alkalosis occurs in the blood at low salinity, indicated by an increase in HCO3− and pH at constant PCO2. The alkalosis is closely correlated with an increase in the Na+-Cl− difference, a convenient indicator of the overall strong ion difference. The contribution of changes in PCO2 to acid-base changes was negligible, but the change in the total weak acid (proteins) may be important. It is suggested that the change in blood acidbase status with salinity is related to an increase in the strong ion difference, which changes during the transition from osmoconformity to osmoregulation in the blue crab, and which is related to both carbonic anhydrase and ionactivated ATPases. Note:

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