asidosis dan alkalosis respiratorik

8/10/2019 Asidosis Dan Alkalosis Respiratorik

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sensor

Biochemistry departement of medical facultylampung university


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pH

[H+

]


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Acid Base

Notasi pH diciptakan oleh seorang ahli kimia dari Denmark yaituSoren Peter Sorensen pada thn 1909, yang berarti log negatif darikonsentrasi ion hidrogen. Dalam bahasa JermandisebutWasserstoffionenexponent (eksponen ion hidrogen) dandiberi simbol pH yang berarti: potenz (power) of Hydrogen.


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Maintenance of relatively constant blood pH value is essential

for health, since changes in blood pH will affect intracell pHalter : - metabolism

- protein conformation

- enzyme activity

- equilibria of reaction that consume / generate H+

(oxidation - reduction reaction)

Maintenance of a constant blood pH is, in part, achieved by

- buffer system in the bloodcontrol short - termchanges in acid - base metab.

- in long term : balancing proton loss & proton gain

Syazi li Mu


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pH value of plasma may be affected by :

- malfunctioning of buffer system or

- disturbance of acidbase balance

e.g. due to - kidney disease or

- altered breathing frequency ( hypo

/ hyperventilation)

Normal alterial plasma pH : 7.40 0.05

- pH < 7.35acidosis

- pH > 7.45alkalosis

Syazili Mustofa


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3 major body water components :

- plasma : within circulating system

- interstitial fluid : fluid that bathes cells

- intracellular fluidComposition :

- plasma : - major kation : Na+

- small amounts : K+, Ca2+, Mg2+

- dominant anions : HCO3-, Cl-

- small amount anion : protein, HPO42-, SO4

2-

- mixture organic anions- interstitial fluid : - similar

- contain less protein

plasma & interst. fluidextracell. Fluid

- intracell fluid : - major kation : K+

- major anions : - organic P (ATP, BPG, glycolitic intrmd)

- protein

Syazili Mustofa


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Each fluid makes a different contribution to buffering

* Major buffer of extracell fluid : HCO3-/ CO2system

- not very effective in resisting pH changes from

changes in pCO2

- effective in controlling pH changes caused by other

than pCO2changes

* Intracell fluid : responsible for buffering pCO2changes

( Hb buffering within RBC)

* Extracell fluid & intracell fluid : equal in buffering strong

organic / inorganic acids Plasma : excellent indicator to handle additional loads of

acids

Syazili Mustofa


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Every buffer consist of : - a weak acid : H A

- conjugate base : A-

e.g. acetate-/acetic acid, NH3 / NH4+, HPO4

2- / H2PO4-

- weak acid : neutral, (+) charged, (-) charged

- conjugate base : 1 less (+) charge / 1 more (-) charge

than weak acid

Henderson - Hesselbalch equation :

pH = pK + log

direct relationship between pH & ratio .

[conj. base ]

[acid]

Syazili Mustofa


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[HCO3-] / [CO2] buffer system :

Blood pH : 7,4

p.k. : 6,1

[HCO3-] / [CO2] ratio = 20/1 at normal blood pH = 7,4

Every changes in [HCO3-] or [CO2]changes the ratio

changes pHcompensation to normalize blood pH.

7,4 = 6,1 + log 20/1

Syazili Mustofa


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Blood plasma is a mixed buffer system :

HCO3- / CO2, HPO4

2-/ H2PO4-, protein / H protein

Major buffer of plasma : bicarbonate buffer system

an open system : pCO2is adjusted to meet the

bodys needs

If respiration can not accomplish this adjustment

pCO2changes strikinglybicarbonate syst. would

be ineffective.

Syazili Mustofa


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* Respiratory acidosis: result of hypoventilation of alveoli

CO2accumulates

Alv. hypoventilation : occur when depth or rate of respiration

- airway obstruction

- neuromuscular disorders

- diseases of CNS

- chronic resp. acidosis : chronic obstructive lung

disease (emphyema)

- inhalation of gas mixture with high pCO2 resp. acidosis

Increase the PCO2 ------> the pH goes down. Hypovent i lat ion.

Acute resp. acidosi

Syazili Mustofa


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* Respiratory alkalosis : arises from decreased alv. pCO2

Hyperventilation : - anxiety : most common cause

- CNS injury involving resp. center

- salicylate poisoning

- fever

- artificial ventilation

High altitude alv. pCO2chronic resp. alkalosis

Decrease the PCO2 ------> the pH goes up. Hypervent i lat ion.

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S l M f


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* Metabolic acidosis

The body produced nonvolatile acids H+ + SO42-

- hydrolysis of phosphate- estersphosphoric acid

- metabolism - lactic acid

- acetoacetic acid

- - hydr. butyric acid

- administration of : NH4Cl / Arghydrochloride / Lys

hydrochloride urea + HCl

Decrease the HCO3------> the pH goes down

produced in excess

accumulationacidosis

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S ili M f


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- ingestion of salicylate, methyl alcohol, ethylene glycol

production of strong organic acid

accumulation of nonvolatile acidsmetabolic acidosis

- abnormal loss of base ;

- renal tubular acidosis : abnormal amount of HCO3-

escape from blood into urine

- severe diarrhea HCO3-

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S ili M t f


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* Metabolic alkalosis

- intake excess alkali :

- NaHCO3

- salt of organic acid : Na - lactateNaHCO3

- fruits & vegetables : contain mixture of organic acids

- metabolized to CO2 + H2Ono long term. effect on acidbase balance

- salt of organic acids [HCO3-]

- abnormal loss of acids : vomiting, gastric lavage (Lose enough stomach acid to

produce alkalosis)

- rapid loss of body water :diuresistemporary [HCO3-]

Increase the HCO3------> the pH goes up

Syazili Mustofa


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Syazili Mustofa


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Normal

Acidosis

- Respiratory

- Metabolic

Alkalosis

- Respiratory

- Metabolic

Blood

pH

7,4

Urine

pH

67

[HCO3-]/

[H2CO3

20/1

20 / > 1

< 20 / 1

20 / < 1

>20 / 1

Cause

Hypoventilation

H+production

or HCO3-excretion

Hyperventilation

Alkali ingestion

or H+excretion

Syazili Mustofa


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Kardiovaskular

Konstriksi arteri

Penurunan aliran darah koroner

Penurunan ambang angina

Predisposisi terjadinya supraventrikel dan ventrikelaritmia yg refrakter

Respirasi

Hipoventilasi yang akan menjadi hiperkarbi dan

hipoksemia

Metabolic

Stimulasi glikolisis anaerob dan produksi asam organik

Hipokalemia

Penurunan konsentrasi Ca terionisasi plasma

Hipomagnesemia and hipophosphatemia

Otak

Penurunan aliran darah otak

Tetani, kejang, lemah delirium dan stupor

Management of life-threatening Acid-Base Disorders, Horacio J. Adrogue, And Nicolaos EM:

Review Article;The New England Journal of Medicine;1998


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Essentially, the difference between theconcentrations of cations (Na+ primarily) andanions (Cl-, HCO3-) in the blood.

Anion gap = ( Na + K )( Cl + HCO)

= 4-17 mmol l


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High Anion Gap: It is high in any condition withreduced clearance or excess production of anyunmeasured anions. Metabo l ic Acido sis. Itind icates that you have added acids to the

blood : salicy l ic acid, formic acid, lactic acid,oxalic acid, sulfuric acid.Normal Anion Gap: Resp iratory A cido sis. Itoc curs when you ul t imately becom e acido t icbecause of losing HCO3

It is low in hyperalbuminaemia, liver disease andparaproteinaemias


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Item value

pH 7,4

[HCO3-] 22 - 28 mEq / L

PaCO2 33 - 44 mEq / L

PaO2 90 - 100 mEq / L

Inget

brho.


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Chronic control

(long-term)

Rapid regulation

(short-term)


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PCO2

PPOK

pH

NH4Cl

Hipoalbumin..?

Sintesis Alb

asidosis dan alkalosis respiratorik

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