acid-base balance
DESCRIPTION
ACID-BASE BALANCE. By: Husnil Kadri Biochemistry Departement Medical Faculty Of Andalas University Padang. Hendersen-Hasselbalch (1909). CARA TRADISIONAL :. HCO 3. HCO 3. [HCO 3 - ]. BASA. GINJAL. Normal. pH = 6.1 + log. Kompensasi. CO 2. pCO 2. PARU. ASAM. CO 2. - PowerPoint PPT PresentationTRANSCRIPT
ACID-BASE BALANCE ACID-BASE BALANCE
By:By:
Husnil KadriHusnil Kadri
Biochemistry Departement
Medical Faculty Of Andalas University
Padang
2
CARA CARA TRADISIONAL :TRADISIONAL :
Hendersen-Hendersen-HasselbalchHasselbalch(1909) (1909)
3
pH pH = 6.1 + log= 6.1 + log[HCO[HCO33
--]]
pCOpCO22
GINJALGINJAL
PARUPARU
BASA BASA
ASAMASAM CO2
HCO3HCO3
CO2
KompensasiKompensasi
NormalNormal
NormalNormal
4
Carbonic acid/bicarbonate buffer systemCarbonic acid/bicarbonate buffer system
• The pKa of carbonic acid is 6.1
• Carbonic acid is the major buffer in ECF
• The pH of blood can be determined using the Henderson-Hasselbalch equation
H2CO3 H+ + HCO3-
Carbonic acid Bicarbonate ion
pKa = 6.1
ECF:
5
• pH = pKa + log [HCO3-]/[H2CO3]
• pH = pKa + log [HCO3-]/0.03 x PCO2
• 7.4 = 6.1 + log 20 / 1
• 7.4 = 6.1 + 1.3
• Plasma pH equals 7.4 when buffer ratio is 20/1
• The solubility constant of CO2 is 0.03
Henderson-Hasselbalch equationHenderson-Hasselbalch equation
DISORDER pH PRIMER RESPON KOMPENSAS
I
ASIDOSIS ASIDOSIS METABOLIKMETABOLIK
HCO3- pCO2
ALKALOSIS ALKALOSIS METABOLIKMETABOLIK
HCO3- pCO2
ASIDOSIS ASIDOSIS RESPIRATORRESPIRATOR
II
pCO2 HCO3-
ALKALOSIS ALKALOSIS RESPIRATORRESPIRATOR
II
pCO2 HCO3-
GANGGUAN KESEIMBANGAN ASAM-GANGGUAN KESEIMBANGAN ASAM-BASA TRADISIONALBASA TRADISIONAL
Normal 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.
Mixed 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.
DUA VARIABELDUA VARIABEL
pH atau [HpH atau [H++] DALAM PLASMA ] DALAM PLASMA DITENTUKAN OLEHDITENTUKAN OLEH
VARIABELVARIABELINDEPENDENINDEPENDEN
Stewart PA. Can J Physiol Pharmacol 61:1444-1461, 1983.
VARIABELVARIABELDEPENDENDEPENDEN
Cara Stewart ;Cara Stewart ;
Strong IonsStrong IonsDifferenceDifference
pCOpCO22
ProteinProteinConcentrationConcentration
pHpH
INDEPENDENT VARIABLESINDEPENDENT VARIABLES DEPENDENT VARIABLESDEPENDENT VARIABLES
VARIABEL INDEPENDENVARIABEL INDEPENDEN
COCO22 STRONG ION STRONG ION DIFFERENCEDIFFERENCE
WEAK ACIDWEAK ACID
pCOpCO22 SIDSID AAtottot
DEPENDENT VARIABLESDEPENDENT VARIABLES
HH++
OHOH--
CO3CO3-- AA--
AHAH
HCO3-HCO3-
COCO22 Didalam plasma berada Didalam plasma berada
dalam 4 bentukdalam 4 bentuk sCOsCO22 (terlarut) (terlarut)
HH22COCO33 asam karbonat asam karbonat
HCOHCO33-- ion bikarbonat ion bikarbonat
COCO332-2- ion karbonat ion karbonat
Rx dominan dari CORx dominan dari CO22 adalah rx adalah rx
absorpsi OHabsorpsi OH-- hasil disosiasi air hasil disosiasi air dengan melepas Hdengan melepas H++..
Semakin tinggi pCOSemakin tinggi pCO22 semakin semakin
banyak Hbanyak H++ yang terbentuk. yang terbentuk. Ini yg menjadi dasar dari Ini yg menjadi dasar dari
terminologi “respiratory acidosis,” terminologi “respiratory acidosis,” yaitu pelepasan ion hidrogen akibat yaitu pelepasan ion hidrogen akibat pCO pCO22
COCO22
Definisi:Definisi:Strong ion difference adalah ketidakseimbangan Strong ion difference adalah ketidakseimbangan muatanmuatan dari ion-ion kuat. Lebih rinci lagi, SID adalah jumlah dari ion-ion kuat. Lebih rinci lagi, SID adalah jumlah
konsentrasi basa kation kuat dikurangi jumlah dari konsentrasi basa kation kuat dikurangi jumlah dari konsentrasi asam anion kuat. Untuk definisi ini semua konsentrasi asam anion kuat. Untuk definisi ini semua konsentrasi ion-ion diekspresikan dalam ekuivalensi konsentrasi ion-ion diekspresikan dalam ekuivalensi (mEq/L).(mEq/L).
Semua ion kuat akan terdisosiasi sempurna jika berada didalam Semua ion kuat akan terdisosiasi sempurna jika berada didalam larutan, misalnya ion natrium (Nalarutan, misalnya ion natrium (Na++), atau klorida (Cl), atau klorida (Cl--). Karena ). Karena selalu berdisosiasi ini maka ion-ion kuat tersebut tidak selalu berdisosiasi ini maka ion-ion kuat tersebut tidak berpartisipasi dalam reaksi-reaksi kimia. Perannya dalam kimia berpartisipasi dalam reaksi-reaksi kimia. Perannya dalam kimia asam basa hanya pada hubungan elektronetraliti.asam basa hanya pada hubungan elektronetraliti.
Gamblegram
NaNa++
140140
KK+ + 44CaCa++++
MgMg++++
ClCl--
102102
KATION ANION
SIDSID
STRONG ION STRONG ION DIFFERENCEDIFFERENCE
[Na+] + [K+] + [kation divalen] - [Cl-] - [asam organik kuat-]
[Na+] + [K+] - [Cl-] = [SID]
140 mEq/L + 4 mEq/L - 102 mEq/L = 34 mEq/L
SIDSID(–) ((++))
[H[H++]] [OH[OH--]]
Dalam cairan biologis (plasma) dgn suhu 370C, SID hampir selalu positif, biasanya berkisar 30-40 mEq/Liter
AsidosisAsidosis AlkalosisAlkalosis
Konsentrasi [H+]
Kombinasi protein dan posfat disebut asam lemah total (total weak acid) [Atot]. Reaksi disosiasinya adalah:
[A[Atottot] (KA) = [A] (KA) = [A--].[H].[H++]]
[Protein H] [Protein-] + [H+]
WEAK ACIDWEAK ACID
disosiasi
Gamblegram
NaNa++
140140
KK+ + 44CaCa++++
MgMg++++
ClCl--
102102
HCOHCO33--
2424
KATION ANION
SIDSID
Weak acidWeak acid(Alb-,P-)(Alb-,P-)
NaNa140140
KKMgMgCaCa
ClCl102102
PPAlbAlb
HCOHCO33 = 24 = 24
ClCl115115
PPAlbAlb
HCOHCO33--
Asidosis hiperklore
mi
SID nSID
ClCl102102
Laktat/keto=UA
Keto/laktat
asidosisCLCL9595
PPAlbAlb
SID
Alkalosis hipoklore
miKATIONKATION ANIONANION
H3O+ = H+ = 40 mEq/LHCOHCO33
--
HCO3-
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):2246-51
ASIDOSIS ALKALOSIS
I. Respiratori PCO2 PCO2
II. Nonrespiratori (metabolik)
1. Gangguan pd SID
a. Kelebihan / kekurangan air [Na+], SID [Na+], SID b. Ketidakseimbangan anion
kuat:
i. Kelebihan / kekurangan Cl- [Cl-], SID [Cl-], SID ii. Ada anion tak terukur [UA-], SID
2. Gangguan pd asam lemah
i. 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):2246-51
RESPIRASIRESPIRASI M E T A B O L I KM E T A B O L I K
Abnormal Abnormal pCO2pCO2
AbnormalAbnormalSIDSID
AbnormalAbnormalWeak acidWeak acid
AlbAlb PO4-PO4-
AlkalosisAlkalosis
AsidosisAsidosis
TurunTurun
MeningkatMeningkat
TurunTurun
kelebihankelebihan
kekurangankekurangan
PositifPositif meningkatmeningkat
Fencl V, Am J Respir Crit Care Med 2000 Dec;162(6):2246-51
AIRAIR Anion kuatAnion kuat
Cl-Cl- UA-UA-
HipoHipo
HiperHiper
Na+ = 140 mEq/LCl- = 102 mEq/LSID = 38 mEq/L
140/1/2 = 280 mEq/L102/1/2 = 204 mEq/L SID = 76 mEq/L
1 liter ½ liter
KEKURANGAN AIR - WATER DEFICITKEKURANGAN AIR - WATER DEFICITDiuretic
Diabetes Insipidus
Evaporasi
SID : 38 SID : 38 76 = 76 = alkalosisalkalosis
ALKALOSIS KONTRAKSIALKALOSIS KONTRAKSI
Plasma Plasma
Na+ = 140 mEq/LCl- = 102 mEq/L SID = 38 mEq/L
140/2 = 70 mEq/L102/2 = 51 mEq/L SID = 19 mEq/L
1 liter 2 liter
KELEBIHAN AIR - WATER EXCESSKELEBIHAN AIR - WATER EXCESS
1 Liter H2O
SID : 38 SID : 38 19 = 19 = AcidosisAcidosis
ASIDOSIS DILUSIASIDOSIS DILUSI
Plasma
Na+ = 140 mEq/L Cl- = 95 mEq/L
SID = 45 mEq/L 2 liter
ALKALOSIS HIPOKLOREMIKALKALOSIS HIPOKLOREMIK
SID ALKALOSIS
GANGGUAN PD SID:GANGGUAN PD SID:Pengurangan ClPengurangan Cl--
Plasma
Na+ = 140 mEq/L Cl- = 120 mEq/LSID = 20 mEq/L 2 liter
ASIDOSIS HIPERKLOREMIKASIDOSIS HIPERKLOREMIK
SID ASIDOSIS
GANGGUAN PD SID:GANGGUAN PD SID:Penambahan/akumulasi Penambahan/akumulasi
ClCl--
Plasma
Na+ = 140 mEq/LCl- = 102 mEq/LSID = 38 mEq/L
Na+ = 154 mEq/LCl- = 154 mEq/LSID = 0 mEq/L1 liter 1 liter
PLASMA + NaCl 0.9%PLASMA + NaCl 0.9%
SID : 38
Plasma NaCl 0.9%
2 liter
ASIDOSIS HIPERKLOREMIK AKIBAT ASIDOSIS HIPERKLOREMIK AKIBAT PEMBERIAN LARUTAN Na Cl 0.9% PEMBERIAN LARUTAN Na Cl 0.9%
=
SID : 19 SID : 19 AsidosisAsidosis
Na+ = (140+154)/2 mEq/L= 147 mEq/L
Cl- = (102+ 154)/2 mEq/L= 128 mEq/L
SID = 19 mEq/L
Plasma
Na+ = 140 mEq/L Cl- = 102 mEq/L SID= 38 mEq/L
Cation+ = 137 mEq/L Cl- = 109 mEq/LLaktat- = 28 mEq/L SID = 0 mEq/L
1 liter 1 liter
PLASMA + Larutan RINGER PLASMA + Larutan RINGER LACTATELACTATE
SID : 38 SID : 38
Plasma Ringer laktat
Laktat cepat
dimetabolisme
2 liter
=
Normal pH setelah pemberian Normal pH setelah pemberian RINGER LACTATE RINGER LACTATE
SID : 34 SID : 34 lebih alkalosis dibanding jika lebih alkalosis dibanding jika diberikan diberikan NaCl 0.9%NaCl 0.9%
Na+ = (140+137)/2 mEq/L= 139 mEq/L
Cl- = (102+ 109)/2 mEq/L = 105 mEq/L Laktat- (termetabolisme) = 0 mEq/L SID = 34 mEq/L
Plasma
Na+ = 140 mEq/LCl- = 130 mEq/LSID =10 mEq/L
Na+ = 165 mEq/LCl- = 130 mEq/LSID = 35 mEq/L1 liter 1.025
liter
25 mEq NaHCO3
SID SID : 10 : 10 35 : 35 : Alkalosis, pH kembali normal Alkalosis, pH kembali normal namun namun mekanismenya bukan karena pemberian HCOmekanismenya bukan karena pemberian HCO33
-- melainkan karena melainkan karena pemberian Napemberian Na++ tanpa anion kuat yg tidak dimetabolisme seperti Cl tanpa anion kuat yg tidak dimetabolisme seperti Cl --
sehingga SID sehingga SID alkalosis alkalosis
Plasma; asidosis
hiperkloremik
MEKANISME PEMBERIAN NA-BIKARBONAT PADA ASIDOSIS
Plasma + NaHCO3
HCO3 cepat dimetabolis
me
NaNa++ NaNa++
KK
HCO3-
ClCl-- ClCl--
HCO3-
SID
Normal Ketosis
UA = Unmeasured Anion:UA = Unmeasured Anion:Laktat, acetoacetate, salisilat, Laktat, acetoacetate, salisilat,
metanol dll.metanol dll.
A-A-AA--
Keto-
SID KK
Lactic/Keto asidosis
NaNa NaNa NaNa
K K KHCO3
ClCl ClCl ClCl
HCO3HCO3SID
Normal Acidosis Alkalosis
GANGGUAN PD ASAM LEMAH:GANGGUAN PD ASAM LEMAH:Hipo/HiperalbuminHipo/Hiperalbumin-- atau P atau P--
Alb/P Alb/P
AlbAlb--/P/P--
AlbAlb--/P/P--
SIDSID
Alkalosis Alkalosis hipoalbuminhipoalbumin/hipoposfate/hipoposfate
mimi
Asidosis Asidosis hiperprotein/ hiperprotein/
hiperposfatemihiperposfatemi
Anion Gap
• Described by Gamble in 1939• Electroneutrality
• Na+, Cl-, and HCO3 are measured ions
Na + UC = Cl + HCO3 + UA
UC = Sum of unmeasured cations
UA = Sum of unmeasured anions
Anion Gap
Unmeasured Cations:• total 11 mEq/L
– Potassium 4– Calcium 5– Magnesium 2
Unmeasured Anions:• total 23 mEq/L
– Sulfates 1– Phosphates 2– Albumin 16– Lactic acid 1– Org. acids 3
Anion Gap
Na + UC = Cl + HCO3 + UA 140 + 11 = 104 + 24 + 23
151 = 151
UA – UC = Na - (Cl + HCO3);Anion Gap = Na - (Cl + HCO3)
If 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.
Anion 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).
Non anion Gap Acidosis:
• Anion gap = 8-12 mmol/L; caused by a decrease in [HCO3 -] balanced by an increase in chloride (hyperchloremic acidosis). Renal tubular acidosis is a type of non gap acidosis
Increased Anion GapNormal = 8-15
May differ institutionally
• Accumulation of organic acids (ketones, lactate)
• Toxic Ingestions
– methanol, ethylene glycol, salicylates
• Reduced inorganic acid excretion
– phosphates, sulfates
• Decrease in unmeasured cations (unusual)
Increased AG Metabolic Acidosis:
• Methanol• Uremia/Renal
Failure• INH, Iron--lactate• Paraldehyde
• Lactic Acidosis– Has many etiologies– Cyanide, CO, Toluene,
HS– Poor perfusion
• Ethylene glycol• Salicylates
– Methyl salicylate • (Oil of wintergreen)
– Mg salicylate
Levraut J et al. Int Care Med 23:417, 1997
Increased Anion GapNormal = 8-15
May differ institutionally“ion specific electrodes”
• Accumulation of organic acids (ketones, lactate)
• Toxic Ingestions – methanol, ethylene glycol, salicylates
• Reduced inorganic acid excretion– phosphates, sulfates
• Decrease in unmeasured cations (unusual)
44
Decreased or Negative Anion GapClin J Am Soc Nephrol 2: 162-174, 2007
• Low protein most important• Albumin has many unmeasured negative
charges• “Normal” anion gap (12) in cachectic person
– Indicates anion gap metabolic acidosis
• Other etiologies of low AG:– Low K, Mg, Ca, increased globulins (Mult.
Myeloma), I intoxication
• Negative AG– more unmeasured cations than unmeasured
anions– Bromide, Iodide, Multiple Myeloma
Change in Anion Gap vs HCO3
• In simple AG Metabolic Acidosis – decrease in plasma bicarbonate = increase in
AG
Anion Gap = 1
HCO3
• Helpful in identifying mixed disorders
Respiratory Compensationfor
Metabolic Acidosis:• Occurs rapidly• Hyperventilation
– “Kussmaul Respirations”– Deep > rapid (high tidal
volume)• Is not Respiratory Alkalosis
Metabolic Alkalosis:• Calculation not as
accurate • Hypoventilation• Not Respiratory
Acidosis• Restricted by
hypoxemia• PCO2 seldom > 50-55
47
ReferenceReference1. Achmadi, A., George, YWH., Mustafa, I. Pendekatan “Stewart” Pendekatan “Stewart”
Dalam Fisiologi Keseimbangan Asam Basa. 2007Dalam Fisiologi Keseimbangan Asam Basa. 20072. Beaudoin, D. Electrolytes and ion sensitive electrodes. PPT.
2003.3. Ivkovic, A ., Dave, R. Renal review. PPT4. Kersten. Fluid and electrolytes. PPT.5. Marieb, EN. Fluid, electrolyte, and acid-base balance. PPT.
Pearson Education, Inc. 20046. Rashid, FA. Respiratory mechanism in acid-base homeostasis.
PPT. 2005.7. Silverthorn, DU. Integrative Physiology II: Fluid and Electrolyte
Balance. Chapter 20, part B. Pearson Education, Inc. 20048. Smith, SW. Acid-Base Disorders. www.acid-base.com