in the name of godta.mui.ac.ir/sites/ta.mui.ac.ir/files/acid—base balance (2).pdf · mixed acid...

In The name of God

Acid Acid –– base balancebase balance

• Basic facts – repetition

• Regulation of A-B balance

• Pathophysiology of clinically important disorders

AcidAcid--Base Balance Base Balance

Physiology - The pH of ECF is tightly regulated

- Normal: 7: 35 – 7: 45

- Daily production of acid :12000meq

- Removal lung (most)

- kidney (small ,50-100meq/day)but restore buffer capacity (HCO3)¯¯¯

- Respiratory or renal disfunctionbreakdown in processacid-base disorders

Organs involved in the regulation of Organs involved in the regulation of AA--BB--balancebalance

– Equilibrium with plasma

– High buffer capacity

Haemoglobin – main buffer for CO2

– Excretion of CO2 by alveolar ventilation: minimally 12,000 mmol/day

– Reabsorption of filtered bicarbonate: 4,000 to 5,000 mmol/day

– Excretion of the fixed acids (acid anion and associated H+): about 100 mmol/day

Buffer Systems in the Body

Bicarbonate: most important ECF buffer

Phosphate: important ICF and renal tubular buffer

HPO4-- + H+ H2PO4

-

Ammonia: important renal tubular buffer

NH3 + H+ NH4+

Proteins: important ICF and ECF buffers Largest buffer store in the body

Albumins and globulins, such as Hb

H2O + CO2 H2CO3 H+ + HCO3-

Respiratory SystemRespiratory System

Second line of defense again changes in pH

Acts at a moderate speed

Regulates pH by controlling rate of CO2

removal

Kidneys Kidneys

Third line of defense against change in hydrogen ion

concentration

Kidneys require hours to days to compensate

forchanges in body-fluid pH

Control pH of body fluids by adjusting

– H+ excretion

– HCO3- excretion/ reabsorption

– Ammonia secretion

--addition of acid addition of acid [[HH++ ]] &pH&pH

--PH<PH<77..3535= [= [HH++ ]]=blood is acidotic or acidemic=blood is acidotic or acidemic

--PH>PH>77..4545=[H=[H++]]=blood is alkalemic or alkalotic=blood is alkalemic or alkalotic

NORMAL VALUES

Using a normal arterial PCO2 of 40 mm Hg

and a normal serum [HCO3- ] concentration of

24 mEq/L, the normal [H+] in arterial blood is

24 × (40/24) = 40 nEq / L

Effect of PH imbalanceEffect of PH imbalance

Majority of body functions optimally at or near pH

of 7.40

AcidosisCNS depression,lethargy,disorientation,

coma

Alkalosisover exitability of CNSperipheral

nerves,tetany, muscular spasms of extremities,face

body,respiratory failure

Significant pH alteration Heart contractility

PaCOPaCO22

Normal :35-45mmHg

paco2 is respiratory componet of acid base status

regulation: 1) co2 production rate

2) Alveolar ventilation

fever or exercise co2 productionVAnormal paco2

Paco2 is the most reliable index of VE(minute volume)

PaCO2 [H+ ]Respiratory Acidosis

Paco2 [H+ ] = Respiratory Alkalosis

Arterial HcoArterial Hco33¯̄ Normal = 22—26 mEq/ L

Metabolic component of Acid –Base status

Regulation by renal system

Hco3¯PH=Metabolic Alkalosis

Hco3¯PH =Metabolic Acidosis

Hco3¯ may change in response to primary change

of paco2 (12—24 hr )

Co2 + H2O H2co3 H+ + Hco3¯

Paco2 Hco3¯

Paco2Hco3¯

Base Excess & Base deficitBase Excess & Base deficit

BBEE++ BEBE¯̄

Normal : 2mEq/L

Be indicate pure metabolic component

ACoRN © 2005-07

The base deficit (BD) is calculated to estimate the

amount of excess metabolic acid.

BDBD “How much alkali needs “How much alkali needs

to be added to return the to be added to return the

pH to pH to 77..40 40 if the PCOif the PCO22 is is

4040.”.”

Metabolic componentMetabolic component

AcidAcid——Base disordersBase disorders

1 )Simple disorder: Respiratory Acidosis

Respiratory Alkalosis

Metabolic Acidosis

Metabolic Alkalosis

2 ) Mixed disorders

Respiratory AcidosisRespiratory Acidosis -Alveolar Ventilation relative to co2 production

Paco2 (paco2 > 45 mmhg ) or higher than expected level of

compensation

Ethiology :1) Respiratory :

*Acute upper Airway obstruction

*sever diffuse airway obstruction (Acute or

chronic)

* Massive pulmonary edema

2) Nonrespiratory:

* Drug overdose

*Spinal cord trauma

*Neuromuscular disease

*Head trauma

*trauma to thoracic cage

Compensation of Respiratory Compensation of Respiratory

AcidosisAcidosis

Acute :pH paco2 Hco3¯ BE

Partial compensation : PH paco2 Hco3¯ BE

completely compensated :pH normal up to 7.39

paco2 HCO3¯ BE

Acute Respiratory Acidosis:10—15mmHg

paco21mEq/L Hco3¯

Chronic Respiratory Acidosis:10mmhg

paco24mEq/L Hco3¯

Clinical Effect of Respiratory Clinical Effect of Respiratory

AcidosisAcidosis Acute:CNS:Headache,sleepy,lethargy,confusion,

semiconciousness,coma(paco2>70 mmhg)

But chronic :higher level of paco2 may be well tolerated

Hypoxemia may presented

CVS : 1)paco2 vasodilution+COwarm flushed skin +bounding pulse

2) Arrhytmias

3)Cerebral vasodilation ICP,Retinal venous distention , pupilledema & headache

Hco3¯(in compensation of Respiratory Acidosis)Cl level

Respiratory AlkalosisRespiratory Alkalosis

Paco2 <35mmHg

Alveolar Ventilation Relation to co2 Production

Ethiology :Pain, Hypoxemia(pao2<55-60mmHg), Acidosis , Anexity, Mechanical ventilation

pH , paco2 and normal Hco3¯ & BE=uncompensated R Alkalosis

pH7.45 , paco2 , Hco3¯ , BE =partial compensation R Alkalosis

pH in normal range , paco2 , Hco3¯ , BE=Full compensated R Alkalosis

Metabolic AcidosisMetabolic Acidosis Hco3¯ BE

Buffers : production or loss

H+Acid) : load H+ or Excretion

Loss of Hco3¯ : diarrhea , renal disease

Metabolic Acid production: Keto acidosis , lactic acidosis,certain toxins(Metanol)

Post hypocapnia disorder

ANION GAP:Na–(Cl¯+Hco3¯)

Normal10-12mEq/L . With K =1215mEq/L

Normal Anion gap : HCL , diarrhea , RTA , (type 2 , proximal)

High Anion gap :Renal Failure , lactic acidosis , keto acidosis

Metabolic AlkalosisMetabolic Alkalosis

-Hco3¯> Normal

-Accumolation of Hco3¯or H loss

Ethiology: Hypokalemia or hypochloremi

*Nasogastric suction

*persistent vomiting

*post hypercapnia Disorder

*Diuretic therapy

*Steroid therapy

*Excessive Adminstration of sodium bicarbonat

Compensation of M AlkalosidCompensation of M Alkalosid

Hypoventilation paco2(Not in awake paients)

Uncompensated M Alkalosis :Hco3¯ BE

PH & Normal paco2

Partial compensated: ph is not yet normal ,

Hco3¯ BE Paco2>45mmHg

Complet compensation : paco2 enough to

PHNormal

AcidAcid--Base Compensation:Base Compensation:

Parameters: pH PaCO2 HCO3-

(BE)

Metabolic

Alkalosis

Normal

Metabolic

Acidosis

Normal

Respiratory

Alkalosis

Normal

Respiratory

Acidosis

Normal

AcidAcid--Base Partially Compensated:Base Partially Compensated:

Parameters: pH PaCO2 HCO3-

(BE)

Metabolic

Alkalosis

Metabolic

Acidosis

Respiratory

Alkalosis

Respiratory

Acidosis

AcidAcid--Base Fully Base Fully

Compensated:Compensated: Parameters: pH PaCO2 HCO3

-

(BE)

Metabolic

Alkalosis

Normal

>7.40

Metabolic

Acidosis

Normal

<7.40

Respiratory

Alkalosis

Normal

>7.40

Respiratory

Acidosis

Normal

<7.40

Mixed Acid Mixed Acid ––Base disorderBase disorder

When two of the symple are Acid –Base are present simultaneosly

Respiratory & metabolic Acidosis: cardiopulmonary arrest , COPD , Hypoxia , poisoning & Drug overdosage (Barbiturate)

Metabolic & Respiratory Alkalosis :Critical care unit:MV , anxeity , pain , Nasogastric suctioning , vomiting , transfusion, antiacid

Metabolic Acidosis & Respiratory Alkalosis:lactic acidosis(Hypoxia)+MV(Hyper ventilation)

Metabolic Alkalosis & Respiratory Acidosis:COPD+Diuretic therapy

يون هيدروژن اجزاييون هيدروژن اجزاي باز در رابطه با غلظتباز در رابطه با غلظت--پارامتر هاي اسيدپارامتر هاي اسيد تنفسي و اجزاي متابوليكتنفسي و اجزاي متابوليك

اجزا باز-پارامترهاي اسيد

PH غلظت يون هيدروژن

Paco2

Pao2

o2sat

تنفسي , اجزا

Hco3

BE

BEecf

BB

متابوليك , اجزا

Interpretation and discussionInterpretation and discussion PH =7.40

Paco2 =40 mmHg

BE = 2mEq/L

BEecf = <BE

BB = 42 (24+17)

Hco3¯ =24mEq/L

Pao2 =( 80—100) mmHg

O2sat =%97.5

Interpretation and discussionInterpretation and discussion

PH Acidosis PH Alkalosis

PaCo2 Acidosis Paco2 Alkalosis

BE Alkalosis BE Acidosis

Pao2<60mmHg Hypoxia

Sao2<%90 Hypoxia

در شرايط طبيعي و بحرانيدر شرايط طبيعي و بحراني PHPHغلظت يون هيدروژن و غلظت يون هيدروژن و

پارامتر طبيعي كوما تشنج

16 125 40 [ H ]

7/8 6/9 7/4 PH

Interpretation and discussion Interpretation and discussion

PH=7/16 7.35-7.45

Paco2=40mmHg 35-45mmHg

Pao2=60mmHg 80-100mmHg

Sao2=85% >90%

Cao2=11vol% 16-20 vol%

BE= 14 ±2

Hco3¯ = 14mEq/L 22-26mEq/L


PH = 7.49

Paco2 = 32mmHg

Pao2 = 68 mmHg

Sao2=91.5%

Cao2 = 16 vol%

Hco3¯ = 22mEq/L

BE = 1


Ph = 7.41

Paco2 = 61mmHg

Pao2 = 66 mmHg

Sao2=91. 4%

Cao2 = 12.2 vol%

Hco3¯ = 37mEq/L

BE =+11


PH = 6.96

Paco2 = 17mmHg

Pao2 = 110mmHg

Sao2=99. 9%

Cao2 = 19 vol%

Hco3¯ = 3.5mEq/L

BE = 24


PH = 7.53

Paco2 = 31mmHg

Pao2 = 90mmHg

Hco3¯ =25mEq/L

BE = +5mEqL


PH = 7.25

Paco2 = 32mmHg

Hco3¯ =16mEq/L

BE = - 10 mEqL


PH = 7.21

Paco2 = 67mmHg

Pao2 = 49 mmHg

Sao2=76%

Cao2 = 10.4 vol%

Hco3¯ = 26 mEq/L

BE = 2

Hb = 10


PH = 7/409

Paco2 = 27/2

BE = 5/2

Hco3¯ = 16/7

Pao2 = 53

O2sat = 86


PH = 7/197

Paco2 =62

BE = 4/5

Hco3¯ =23.3

Pao2 =30.8

O2sat =42.7

Hb = 15

BB = 43.4


PH = 7/ 14

Paco2 = 67/2

BE = 7.1

BB =40.8

Hco3¯ =22.3

Pao2 = 37

O2sat =50.5

Hb = 15

Interpretation and discussionInterpretation and discussion PH = 7/209

Paco2 =55.8

BE = 6.4

BB = 39.4

Hco3¯ =21.3

Pao2 = 59.6

O2sat = 82.7

Hb = 10

Interpretation and discussionInterpretation and discussion PH = 7.166

Paco2 =42.9

BE = 12.9

BB = 35

Hco3¯ = 15

Pao2 = 57.8

O2sat =78.5

Hb = 15


Paco2 = 24/2

BE = 6

BB = 39.8

Hco3¯ = 16/7

Pao2 =130

O2sat =99

Hb = 10


Paco2 =52

BE =6.2

BB = 41.8

Hco3¯ =21

Pao2 =40.1

O2sat =62.6

Hb = 15


Paco2 = 34.2

BE =12.4

BB = 58.7

Hco3¯ = 33.2

Pao2 =66.1

O2sat =96.5

Hb = 11


Paco2 =53.7

BE =--6.8

BB = 41.1

Hco3¯ =21.5

Pao2 =227.4

O2sat =99.5

Hb = 15


Paco2 =31.7

BE =5.6

BB = 53.6

Hco3¯ = 26/1

Pao2 =40.3

O2sat = 83.2

Hb = 15


Paco2 =33.1

BE = 5/2

BB = 42.8

Hco3¯ = 18.1

Pao2 =41.1

O2sat =73.2

Hb = 15


Paco2 = 32/2

BE = 7.1

BB = 40.8

Hco3¯ = 16/7

Pao2 =106.2

O2sat =97.5

Hb = 14


Paco2 =36.1

BE =--9.7

BB = 38.2

Hco3¯ = 16/1

Pao2 =105.8

O2sat =96.8

Hb = 13


Paco2 =51.8

BE = 9.1

BB = 38.8

Hco3¯ =19.1

Pao2 = 55.4

O2sat =78.2

Hb = 14


Paco2 =50.4

BE =5/7

BB = 53.7

Hco3¯ =30.7

Pao2 =48.6

O2sat = 84.9

Hb = 14


Paco2 =36.7

BE = 13.4

BEecf = -12.9

BB = 32.4

Hco3¯ = 13/7

Pao2 =94.2

O2sat =94

Hb = 10


Paco2 =50.2

BE = 6/7

Beecf = 6.1

BB = 41.2

Hco3¯ =20.1

Pao2 =36

O2sat =54.9

Hb = 14


Paco2 =14.7

BE = 14

Beecf = -15

BB = 31.6

Hco3¯ =8.5

Pao2 =93.2

O2sat =96.6

Hb = 9


PH = 7/258

Paco2 = 20/4

BE = 16.2

Beecf = 16.5

BB = 29.6

Hco3¯ =8.8

Pao2 =91.8

O2sat =94.8

Hb = 10


Paco2 =35.6

BE = 14.7

BEecf = -14

BB = 33.2

Hco3¯ = 12.8

Pao2 =75.4

O2sat =88.9

Hb = 14


PH = 7/44

Paco2 = 24.4

BE = 5/2

BEecf = -6.7

Hco3¯ =41.4

Pao2 =67.2

O2sat =93.7

Hb = 12


Paco2 =30.8

BE =6.4

BEecf = 5.5

BB = 52.3

Hco3¯ =27.4

Pao2 =93.4

O2sat =98.4

Hb = 10


Paco2 =47.8

BE = 12.2

BEecf = -11.1

BB = 34

Hco3¯ = 16/3

Pao2 =119.3

O2sat =96.6

Hb = 11


Paco2 =36.7

BE = 7.6

Hco3¯ = 17/7

Pao2 =92.2

O2sat =95.5

Hb = 10


PH = 7/541

Paco2 =39

BE =10.9

Hco3¯ =33.2

Pao2 =67

O2sat =95.8


PH = 7.609

Paco2 = 31/2

BE =10

Hco3¯ =29.9

Pao2 =82.3

O2sat =98


Paco2 =27.2

BE = 14.4

BEecf = -14.7

BB = 33.5

Hco3¯ = 11.1

Pao2 =65.6

O2sat =86.6

Hb = 14


Paco2 =27.6

BE =-18.1

BEecf = -17.6

BB =29.8

Hco3¯ =9.4

Pao2 =115.8

O2sat =96.1

Hb = 14

Radial Artery

Ulnar Artery

Getting an

arterial blood

gas sample

Neonatal Blood Gases Neonatal Blood Gases --

Sampling PossibilitiesSampling Possibilities Arterial Gases

Venous Gases

Capillary

Capillary GasesCapillary Gases

Drawn from heel

Procedure:

– heel warmed to ‘arterialize’ blood

– lancet puncture

– blood flows, trapped in capillary tube

Preferred Sites

ComparativeComparative

pH pCO2 HCO3 PO2

Arterial 7.4 40 24 60-80

(term)

Arterial 7.4 40 24 50-70

(preterm)

Capillary 7.4 40 24 40-50

Venous 7.35 45 24 35-45

Pulse OximetersPulse Oximeters

Sites of attachment

(foot and hand)

Preductal placement in first twelve hours

(right hand)

ACoRN © 2005-07

Arterial, capillary or venous samples are

nearly equally useful for the determination of

ventilation (PCO2), pH and base deficit but

quite different for oxygenation (PO2, SaO2)

ApplicationApplication

Blood

Pressure

Waveform

ABG Sample Port

Respiratory SystemRespiratory System

Second line of defense again changes in pH

Acts at a moderate speed

Regulates pH by controlling rate of CO2

removal

in the name of godta.mui.ac.ir/sites/ta.mui.ac.ir/files/acid—base balance (2).pdf · mixed acid...

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