4Normal Compensatory Response Any primary disturbance in acid-base homeostasis invokes a normal compensatory response.A primary metabolic disorder leads to respiratory compensation, and a primary respiratory disorder leads to an acute metabolic response due to the buffering capacity of body fluids.A more chronic compensation (1-2 days) due to alterations in renal function.
5Mixed Acid - Base Disorder Most acid-base disorders result from a single primary disturbance with the normal physiologic compensatory response and are called simple acid-base disorders.In certain cases, however, particularly in seriously ill patients, two or more different primary disorders may occur simultaneously, resulting in a mixed acid-base disorder.The net effect of mixed disorders may be additive (eg, metabolic acidosis and respiratory acidosis) and result in extreme alteration of pH;or they may be opposite (eg, metabolic acidosis and respiratory alkalosis) and nullify each other’s effects on the pH.
6KLASIFIKASI GANGGUAN KESEIMBANGAN ASAM BASA BERDASARKAN PRINSIP STEWART Fencl V, Jabor A, Kazda A, Figge J. Diagnosis of metabolic acid-base disturbances in critically ill patients. Am J Respir Crit Care Med 2000 Dec;162(6):
7KLASIFIKASI ASIDOSIS ALKALOSIS I. Respiratori PCO2 PCO2 ASIDOSISALKALOSISI. Respiratori PCO2 PCO2II. Nonrespiratori (metabolik)1. Gangguan pd SIDa. Kelebihan / kekurangan air [Na+], SID [Na+], SIDb. Ketidakseimbangan anion kuat:i. Kelebihan / kekurangan Cl- [Cl-], SID [Cl-], SIDii. Ada anion tak terukur [UA-], SID2. Gangguan pd asam lemahi. Kadar albumin [Alb] [Alb]ii. Kadar posphate [Pi] [Pi]Fencl V, Jabor A, Kazda A, Figge J. Diagnosis of metabolic acid-base disturbances in critically ill patients. Am J Respir Crit Care Med 2000 Dec;162(6):
8Fencl V, Am J Respir Crit Care Med 2000 Dec;162(6):2246-51 RESPIRASIM E T A B O L I KAbnormalpCO2AbnormalSIDAbnormalWeak acidAlbPO4-AIR Anion kuatCl-UA-TurunAlkalosisTurunkekuranganHipoAsidosisMeningkatkelebihanHiperPositifmeningkatFencl V, Am J Respir Crit Care Med 2000 Dec;162(6):
19GANGGUAN PD ASAM LEMAH: Hipo/Hiperalbumin- atau P- HCO3NaHCO3NaHCO3KKKSIDSIDSIDAlb-/P-Alb-/P-Alb/P ClClClAsidosis hiperprotein/ hiperposfatemiAlkalosis hipoalbumin/hipoposfatemiNormalAcidosisAlkalosis
20Calculate the anion gap. Anion gap = Na+ - (Cl- + HCO3 -).Normal anion gap is 8-15 mEq/L.
21If the anion gap is elevated Then compare the changes from normal between the anion gap and [HCO3 -].If the change in the anion gap is greater than the change in the [HCO3 -] from normal, then a metabolic alkalosis is present in addition to a gap metabolic acidosis.If the change in the anion gap is less than the change in the [HCO3 -] from normal, then a non gap metabolic acidosis is present in addition to a gap metabolic acidosis.
22Anion Gap Acidosis:Anion gap >12 mEq/L; caused by a decrease in [HCO3 -]balanced by an increase in an unmeasured acid ion from either endogenous production or exogenous ingestion (normochloremic acidosis).
23Non anion Gap Acidosis: Anion gap = 8-12 mEq/L; caused by a decrease in [HCO3 -] balanced by an increase in chloride (hyperchloremic acidosis). Renal tubular acidosis is a type of non gap acidosisThe anion gap is helpful in identifying metabolic gap acidosis, non gap acidosis, mixed metabolic gap and non gap acidosis. If an elevated anion gap is present, a closer look at the anion gap and the bicarbonate helps differentiate among(a) a pure metabolic gap acidosis(b) a metabolic non gap acidosis(c) mixed metabolic gap and non gap acidosis, and(d) a metabolic gap acidosis and metabolic alkalosis.
25Increased Anion Gap Normal = 8-15 May differ institutionally Accumulation of organic acids (ketones, lactate)Toxic Ingestionsmethanol, ethylene glycol, salicylatesReduced inorganic acid excretionphosphates, sulfatesDecrease in unmeasured cations (unusual)Lactate, Keto acids most common organic acids.AG> 35: M, EG, HHC, LAToxic ingestions: Cyanide, ASA, M, EG, Par, TolueneReduced Inorganic: Renal failure
26Increased AG Metabolic Acidosis: Lactic AcidosisHas many etiologiesCyanide, CO, Toluene, HSPoor perfusionEthylene glycolSalicylatesMethyl salicylate(Oil of wintergreen)Mg salicylateMethanolUremia/Renal FailureINH, Iron--lactateParaldehydeLevraut J et al. Int Care Med 23:417, 1997
27Decreased or Negative Anion Gap Clin J Am Soc Nephrol 2: 162-174, 2007 Low protein most importantAlbumin has many unmeasured negative charges“Normal” anion gap (12) in cachectic personIndicates anion gap metabolic acidosis2-2.5 mEq/liter drop in AG for every 1 g drop in albuminOther etiologies of low AG:Low K, Mg, Ca, increased globulins (Mult. Myeloma), Li, Br (bromism), I intoxicationNegative AGmore unmeasured cations than unmeasured anionsBromide, Iodide, Multiple Myeloma
28SourcesAchmadi, A., George, YWH., Mustafa, I. Pendekatan “Stewart” Dalam Fisiologi Keseimbangan Asam Basa. ppt. 2007Magdy. A. Blood Gases and Acid-Base Disorders. ppt. 2011Paphitou, N. Interpretation of Arterial Blood Gases and Acid-Base Disorders. PPTRashid, FA. Respiratory mechanism in acid-base homeostasis. PPTSmith, SW. Acid-Base Disorders.28