Pathophysiology and causes of metabolic acidosis in the critically ill

2016 ◽  
Author(s):  
Patrick J. Neligan ◽  
Clifford S. Deutschman
Keyword(s):  
Metabolic Acidosis ◽  
Isotonic Saline ◽  
Lactate Production ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Waste Products ◽  
Renal Tubular ◽  
Specific Symptoms ◽  
Symptoms And Signs ◽  
Intracellular Glucose

Critical illness is typically characterized by changes in the balance of water and electrolytes in the extracellular space, resulting in the accumulation of anionic compounds that manifests as metabolic acidosis. Metabolic acidosis manifests with tachypnoea, tachycardia, vasodilatation, headache and a variety of other non-specific symptoms and signs. It is caused by a reduction in the strong ion difference (SID) or an increase in weak acid concentration (albumin or phosphate). Increased SID results from hyperchloraemia, haemodilution or accumulation of metabolic by-products. A reduction in SID results in a corresponding reduction is serum bicarbonate. There is a corresponding increase in alveolar ventilation and reduced PaCO2. Lactic acidosis results from increased lactate production or reduced clearance. Ketoacidosis is associated with reduced intracellular glucose availability for metabolism, and is associated with insulin deficiency and starvation. Hyperchloraemic acidosis is associated with excessive administration of isotonic saline solution, renal tubular acidosis and ureteric re-implantation. Renal acidosis is associated with hyperchloraemia, hyperphosphataemia, and the accumulation of medley nitrogenous waste products.

Equivalent Metabolic Acidosis with Four Colloids and Saline on Ex Vivo Haemodilution

2009 ◽  
Vol 37 (3) ◽  
pp. 407-414 ◽  
Author(s):  
T. J. Morgan ◽  
M. Vellaichamy ◽  
D. M. Cowley ◽  
S. L. Weier ◽  
B. Venkatesh ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Base Excess ◽  
Ex Vivo ◽  
Venous Blood ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Strong Ion Gap ◽  
Acid Base ◽  
Acid Properties

Colloid infusions can cause metabolic acidosis. Mechanisms and relative severity with different colloids are incompletely understood. We compared haemodilution acid-base effects of 4% albumin, 3.5% polygeline, 4% succinylated gelatin (all weak acid colloids, strong ion difference 12 mEq/l, 17.6 mEq/l and 34 mEq/l respectively), 6% hetastarch (non-weak acid colloid, strong ion difference zero) and 0.9% saline (crystalloid, strong ion difference zero). Gelatin weak acid properties were tracked via the strong ion gap. Four-step ex vivo dilutions of pre-oxygenated human venous blood were performed to a final [Hb] near 50% baseline. With each fluid, base excess fell to approximately −13 mEq/l. Base excess/[Hb] relationships across dilution were linear and direct (R2 ≥0.96), slopes and intercepts closely resembling saline. Baseline strong ion gap was −0.3 (2.1) mEq/l. Post-dilution increases occurred in three groups: small with saline, hetastarch and albumin (to 3.5 (02) mEq/l, 4.3 (0.3) mEq/l, 3.3 (1.4) mEq/l respectively), intermediate with polygeline (to 12.2 (0.9) mEq/l) and greatest with succinylated gelatin (to 20.8 (1.4) mEq/l). We conclude that, despite colloid weak acid activity ranging from zero (hydroxyethyl starch) to greater than that of albumin with both gelatin preparations, ex vivo dilution causes a metabolic acidosis of identical severity to saline in each case. This uniformity reflects modifications to the albumin and gelatin saline vehicles, in part aimed at pH correction. By proportionally increasing the strong ion difference, these modifications counter deviations from pure saline effects caused by colloid weak acid activity. Extrapolation in vivo requires further investigation.

Acid-base balance in ducks (Anas platyrhynchos) during involuntary submergence

1987 ◽  
Vol 252 (2) ◽  
pp. R348-R352 ◽  
Author(s):  
M. Shimizu ◽  
D. R. Jones
Keyword(s):  
Protein Content ◽  
Total Protein ◽  
Recovery Period ◽  
Lactate Production ◽  
Weak Acid ◽  
Total Protein Content ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Base Balance

Measurements of all the major independent variables [arterial CO2 tension (PaCO2); strong-ion difference ([SID]), and total protein content, which approximate total weak acid concentration in plasma] are essential for understanding changes in acid-base balance in plasma. During involuntary submergence of 1, 2, or 4 min, PaCO2 in ducks increased and arterial pH (pHa) decreased. During 1-min dives there were no significant changes in any strong ions. In both 2- and 4-min dives, there was a significant increase in [lactate-], but because of an increase in equal magnitude of [Na+], [SID] did not change. During recovery from all dives the plasma remained acidotic for several minutes, although PaCO2 fell below predive levels in less than 1 min. [Lactate-] increased in the recovery period. There were no changes in total protein content during submergence or recovery. Breathing 100% O2 before 2-min dives caused a reduction in [lactate-] production and release during and after the dive, although due to a marked increased in PaCO2, pHa fell as low as in 4-min dives after breathing air. After 1 min of recovery, pHa returned to normal along with the restoration of the predive level of PaCO2. We conclude that the acidosis during involuntary submergence is due solely to an increase in PaCO2, whereas in recovery it is caused by decreased [SID].

Scrub typhus (Orientia tsutsugamushi), A rapidly spreading epidemic in Chennai - A standalone lab experience

2016 ◽  
Vol 5 (09) ◽  
pp. 4896
Author(s):  
Sripriya C.S.* ◽  
Shanthi B. ◽  
Arockia Doss S. ◽  
Antonie Raj I. ◽  
Mohana Priya
Keyword(s):  
Scrub Typhus ◽  
Clinical Symptoms ◽  
Clinical Manifestations ◽  
Febrile Illness ◽  
Orientia Tsutsugamushi ◽  
The Past ◽  
Igm Elisa ◽  
The Mean ◽  
Specific Symptoms ◽  
Symptoms And Signs

Scrub typhus (Orientia tsutsugamushi), is a strict intracellular bacterium which is reported to be a recent threat to parts of southern India. There is re-emergence of scrub typhus during the past few years in Chennai. Scrub typhus is an acute febrile illness which generally causes non-specific symptoms and signs. The clinical manifestations of this disease range from sub-clinical disease to organ failure to fatal disease. This study documents our laboratory experience in diagnosis of scrub typhus in patients with fever and suspected clinical symptoms of scrub typhus infection for a period of two years from April 2014 to April 2016 using immunochromatography and IgM ELISA methods. The study was conducted on 648 patients out of whom 188 patients were found to be positive for scrub typhus. Results also showed that pediatric (0 -12 years) and young adults (20 – 39 years) were more exposed to scrub typhus infection and female patients were more infected compared to male. The study also showed that the rate of infection was higher between September to February which also suggested that the infection rate is proportional to the climatic condition. Statistical analysis showed that the mean age of the patients in this study was 37.6, standard deviation was 18.97, CV % was 50.45. 

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.

scholarly journals Hyperchloremic metabolic acidosis during bipolar transurethral resection of the prostate: a report of two cases

2021 ◽  
Vol 49 (6) ◽  
pp. 030006052110244
Author(s):  
Ann Hee You ◽  
Ji Yoo Lee ◽  
Jeong-Hyun Choi ◽  
Mi Kyeong Kim
Keyword(s):  
Metabolic Acidosis ◽  
Transurethral Resection ◽  
Normal Saline ◽  
Isotonic Saline ◽  
Hemodynamic Instability ◽  
Acid Base ◽  
Electrolyte Disturbance ◽  
Irrigation Fluid ◽  
Laboratory Test Results ◽  
Hyperchloremic Metabolic Acidosis

Compared with monopolar transurethral resection of the prostate (TURP), which requires electrolyte-free irrigation fluid, normal saline can be used as the irrigation solution in bipolar and laser TURP. The risk of TURP syndrome and severe electrolyte disturbance is minimized when normal saline is used as the irrigation fluid. However, the use of isotonic saline also causes acid-base imbalance and electrolyte disturbance. We experienced two patients who developed hyperchloremic metabolic acidosis during bipolar TURP. After proper intervention, hemodynamic instability resolved, and laboratory test results normalized. Anesthesiologists must pay attention to acid-base and electrolyte status when rapid absorption of excessive isotonic solution is suspected, even during bipolar and laser TURP, which use normal saline as the irrigation fluid.

Physicochemical analysis of phasic menstrual cycle effects on acid-base balance

2001 ◽  
Vol 280 (2) ◽  
pp. R481-R487 ◽  
Author(s):  
Robert J. Preston ◽  
Aaron P. Heenan ◽  
Larry A. Wolfe
Keyword(s):  
Menstrual Cycle ◽  
Ventilatory Threshold ◽  
Physicochemical Analysis ◽  
Carbon Dioxide Tension ◽  
Weak Acid ◽  
Ion Concentration ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Hydrogen Ion Concentration ◽  
Base Balance

In accordance with Stewart's physicochemical approach, the three independent determinants of plasma hydrogen ion concentration ([H+]) were measured at rest and during exercise in the follicular (FP) and luteal phase (LP) of the human menstrual cycle. Healthy, physically active women with similar physical characteristics were tested during either the FP ( n = 14) or LP ( n = 14). Arterialized blood samples were obtained at rest and after 5 min of upright cycling at both 70 and 110% of the ventilatory threshold (TVent). Measurements included plasma [H+], arterial carbon dioxide tension (PaCO2 ), total weak acid ([ATot]) as reflected by total protein, and the strong-ion difference ([SID]). The transition from rest to exercise in both groups resulted in a significant increase in [H+] at 70% TVentversus rest and at 110% TVent versus both rest and 70% TVent. No significant between-group differences were observed for [H+] at rest or in response to exercise. At rest in the LP, [ATot] and PaCO2 were significantly lower (acts to decrease [H+]) compared with the FP. This effect was offset by a reduction in [SID] (acts to increase [H+]). After the transition from rest to exercise, significantly lower [ATot] during the LP was again observed. Although the [SID] and PaCO2 were not significantly different between groups, trends for changes in these two variables were similar to changes in the resting state. In conclusion, mechanisms regulating [H+] exhibit phase-related differences to ensure [H+] is relatively constant regardless of progesterone-mediated ventilatory changes during the LP.

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