respiratory module acid-base disturbances. regulation of acid-base balances normal plasma ph –...

Respiratory Module

Acid-Base Disturbances

Regulation of Acid-Base balances

• Normal plasma pH– 7.35-7.45

• pH is the indicator of– H+ ion concentration

• pH range compatible with life– 6.8 – 7.8

Learning Tip

• BASE – ALKALINE– pH– Base = alkaline = pH

• Acid– Acidic– pH– Acid = acidic = pH

• 3 Bases• 3 Acids• 3B = 3A• pH =

– Homeostasis– 7.40

• 4 Bases– High

• 4 Acids– High

• 4B = 4A• pH =


• 2 Bases– Low

• 2 Acids– Low

• 2B = 2A• pH =


• 4 Bases (alkaline)– High

• 3 Acids (acidic)– Normal

• 4B > 3A• pH =

– Alkalosis– > 7.45

• 3 Bases (alkaline)– Normal

• 4 Acids (acidosis)– High

• 3B < 4A• pH =

– Acidosis– < 7.35

• 3 Bases– normal

• 2 Acids– Low

• 3B > 2A• pH =

– Alkalosis– > 7.45

• 2 Bases– low

• 3 Acids– normal

• 2B < 3A• pH =

– Acidosis– < 7.35

Learning Tip

•Normal Acid & Base = pH = Alkalosis

•Normal Acid & Base = pH =Acidosis

• Acid & Normal Base = pH =Acidosis• Acid & Normal Base = pH = Alkalosis

Chemical Buffers• The body’s major buffer system is

– The bicarbonate-carbonic acid buffer system• Bicarbonate

– HCO3-

– Base– Alkaline

• Carbonic acid– H2CO3

– Acid– Acidic

Chemical Buffers

• Carbonic Acid– CO2 + H20 = H2CO3– When CO2 is increased

• Carbonic acid is increased

– When CO2 is decreased• Carbonic acid is decreased

Kidneys

• The kidneys regulate – The bicarbonate level HCO3-

• The kidneys are able to reabsorb as well as excrete– Bicarbonate ions (HCO3-) from the renal tubules

Kidneys

• If the kidneys retain / reabsorb bicarbonate– HCO3 plasma (base)– pH

• If the kidneys excrete bicarbonate– HCO3 plasma (base)– pH

Kidneys

• If the plasma pH is acidic (pH: A > B) the kidneys will compensate by…– Retain / reabsorb bicarbonate (HCO3

-) to help restore balance

– HCO3- in the blood

– serum pH– 4A > 3B 4A = 4B

Kidneys

• If the plasma pH is alkaline (pH 3A > 4B or 2A >

3B) the kidneys will…– Excrete bicarbonate (HCO3-) to help restore

balance– HCO3– pH– 2A < 3B 2A = 2B

Kidneys

• Restoration of a balances pH is called:– COMPENSATION

• Renal compensation is:– Relatively slow– Takes hours - days

Lungs

• The lungs regulate – The Carbonic acid level / CO2

• The lungs are able to retain as well as excrete – CO2

Lungs

• Decrease in respiratory rate– CO2 (acid)– pH

• Increase in respiratory rate– CO2 (acid)– pH

Lungs

• If the plasma pH is acidic ( pH = 4A > 3B or 3A > 2B) the lungs will try to restore balance by…– Hyperventilating– CO2– pH– 4A > 3B 3A = 3B

Lungs

• If the plasma pH is alkaline ( pH = 3A < 4B or 2A < 3B) the lungs will try to restore balance by…– Hypoventilating– CO2– pH– 3A < 4B 4A = 4B

Learning Tip

Respiratory = Lungs = CO2 = Acid

Metabolic = Kidneys = HCO3 = Base

Practice Questions

1. HCO3- : 45

2. HCO3- : 24

3. PaCO2: 60

4. HCO3- : 18

5. PaCO2: 20

Practice Questions

1. HCO3-: 322. PaCO2: 40 3. HCO3-: 124. PaCO2: 535. PaCO2: 24

More practice questions

1. PaCO2: 652. PaCO2: 353. PaCO2: 524. PaCO2: 205. HCO3: 186. HCO3: 247. HCO3: 308. HCO3: 12

Respiratory Acidosis:Characteristics

• pH– < 7.35

• PaCO2– > 45 mmHg– Hypercapnia

• Metabolic Compensation– HCO3-– Kidneys reabsorb and retain HCO3

Respiratory Acidosis:Clinical Manifestations

• Feeling of fullness in the head• pulse and BP• Mental cloudiness• Weakness

Respiratory Acidosis:Etiology

Always d/t inadequate excretion of CO2• Hypoventilation• Pulmonary edema• Aspiration• Atelectasis• Overdose of sedatives

Respiratory Acidosis:Management

• Improve ventilation• Bronchodilators, antibiotics, pulmonary

hygiene measures

Metabolic Alkalosis:Characteristics

• pH– > 7.45

• Bicarbonate / HCO3-– > 26 mEq/l

• Respiratory compensation– CO2 by

• Hypoventilation

Metabolic Alkalosis:Clinical Manifestations

• Ca+• Tingling of the fingers • Hypertonic muscles• Atrial tachycardia• Tetany

Metabolic Alkalosis:Etiology

• #1– Vomiting or gastric suction

• Long term diuretics

Metabolic Alkalosis:Management

• Reverse underlying disorder• Restore normal fluid & electrolytes

Respiratory Alkalosis:Characteristics

• pH– > 7.45

• PaCO2– < 35 mmHg

• Metabolic Compensation– ↓ HCO3 by

• The kidney will excrete HCO3

Respiratory Alkalosis:Clinical Manifestations

• Lightheadedness• concentration• LOC

Respiratory Alkalosis:Etiology

• Hyperventilation– Extreme anxiety– Gram-negative bacteria– Excessive ventilation by mechanical ventilators

Respiratory Alkalosis:Management

• If anxiety breath more slowly• Breath into a closed system

Metabolic Acidosis: Characteristics

• pH – < 7.35

• Bicarbonate - HCO3– < 22

• Respiratory Compensation– CO2 by

• Hyperventilation

Metabolic Acidosis: Clinical Manifestations

• Confusion, H/A, drowsy• N&V• Cold clammy skin• Dysrhythmias• Hyperkalemia• Shock

Metabolic Acidosis: Etiology

• Renal failure• Diabetic ketoacidosis• Lactic acidosis• Salicylate poisoning• Diarrhea

Metabolic Acidosis:Management

• Correct metabolic defect• Watch K+ levels

Mixed acid-base disorders

• Is it possible to pat to have both respiratory and metabolic imbalances at the same time?– YES!

Compensation

• The pulmonary system and the renal will compensate for each other to return to pH to normal

• The lungs compensate for metabolic disturbances by altering the PaCO2 levels by Hyper/hypoventilation

• The kidneys compensate for respiratory disturbances by altering the HCO3- levels by reabsorbing retaining or excreting HCO3

Compensation

• Respiratory acidosis– Kidneys retain HCO3

• Respiratory alkalosis– Kidneys excrete HCO3

• Metabolic acidosis– Lungs excrete CO2 (hyperventilate)

• Metabolic alkalosis– Lungs retain CO2 (hypoventilate)

Medications & acid-base disturbances

• Diuretics – Metabolic Alkalosis

• Steroids– Metabolic alkalosis

• Narcotics– Respiratory acidosis

Blood Gas Analysis

pH 7.35 – 7.45

PaO2 80-100 mmHg

PaCO2 35-45 mmHg

HCO3- 22-26 mEq/l

Base Excess

-2 to +2

Si02 95 – 100%

• pH– Acidity / alkalinity

• PaO2– Not primary in acid-

base regulation– Change with O2

administration– < 60 acidosis– < 80 Hypoxemia

Blood Gas Analysis

pH 7.35 – 7.45

PaO2 80-100 mmHg

PaCO2 35-45 mmHg

HCO3- 22-26 mEq/l

Base Excess

-2 to +2

Si02 95 – 100%

• PaCO2– Effective ventilation– PaCO2

• Hypoventilation– PaCo2

• Hyperventilation

• HCO3-– Renal component– Kidney excrete or

retain

Blood Gas Analysis

pH 7.35 – 7.45

PaO2 80-100 mmHg

PaCO2 35-45 mmHg

HCO3- 22-26 mEq/l

Base Excess

-2 to +2

Si02 95 – 100%

• Base Excess– Amount of blood

buffer• High

– Alkalosis

• Low– Acidosis

• SiO2– % of Hgb saturated

with O2

Steps to Blood Gas Analysis

1. Label the pH, PaCO2 & HCO3-

• Serum pH > 7.4– Alkalosis

• Serum pH < 7.4– Acidosis

• Serum pH = 7.4– Homeostasis


• Label the PaCO2 & HCO3-– PaCO2

• Acidosis– PaCO2

• Alkalosis– HCO3-

• Alkalosis– HCO3-

• Acidosis


2. Find the Cause of the acid-base disturbance• pH > 7.4 Alkalosis

– If the PaCO2 is < 40 = respiratory alkalosis– If the HCO3- is > 24 = metabolic alkalosis

• pH < 7.4 Acidosis – If the PaCO2 > 40 = respiratory acidosis– If the HCO3- is < 24 = metabolic acidosis


3. Check for compensation• The body tries to restore balance by altering

the buffer of the system that is not involved in the imbalance

• If compensation has occurred the values will move in the same direction as the other component.

Practice #1

pH 7.53

PaO2

PaCO2 42

HCO3- 34

Base Excess

SiO2

• Metabolic Alkalosis with NO respiratory compensation

Practice #2

pH 7.27

PaO2

PaCO2 38

HCO3- 14

Base Excess

SiO2

• Metabolic Acidosis with NO respiratory compenstation

Practice #3

pH 7.54

PaO2 50

PaCO2 30

HCO3- 25

Base Excess

SiO2

• Respiratory Alkalosis with NO metabolic compensation

Practice #4

pH 7.50

PaO2 85

PaCO2 40

HCO3- 30

Base Excess

SiO2


Practice #5

pH 7.30

PaO2 40

PaCO2 56

HCO3- 26

Base Excess

SiO2

• Respiratory acidosis with NO metabolic compensation

Practice #6

pH 7.23

PaO2 90

PaCO2 40

HCO3- 16

Base Excess

SiO2

• Metabolic Acidosis with NO respiratory compensation

Practice #7

pH 7.30

PaO2 50

PaCO2 60

HCO3- 30

Base Excess

SiO2

• Respiratory Acidosis with partial metabolic compensation

Practice #8

pH 7.45

PaO2 50

PaCO2 50

HCO3- 34

Base Excess

SiO2

• Metabolic Alkalosis with complete/full respiratory compensation

Practice #9

pH 7.35

PaO2 85

PaCO2 64

HCO3- 34

Base Excess

SiO2

• Respiratory acidosis with complete/full metabolic compensation

Practice #10

pH 7.45

PaO2 80

PaCO2 35

HCO3- 24

Base Excess

SiO2

• Normal

Practice #11

pH 7.27

PaO2 95

PaCO2 55

HCO3- 24

Base Excess

SiO2

• Respiratory acidosis with NO metabolic compensation

Practice #12

pH 7.50

PaO2 85

PaCO2 40

HCO3- 30

Base Excess

SiO2


Practice #13

pH 7.14

PaO2 80

PaCO2 80

HCO3- 19

Base Excess

SiO2

• Respiratory & Metabolic Acidosis with no respiratory or metabolic compensation

Practice #14

pH 7.56

PaO2

PaCO2 40

HCO3- 45

Base Excess

SiO2


Practice #15

pH 7.35

PaO2

PaCO2 58

HCO3- 31

Base Excess

SiO2


Practice #16

pH 7.31

PaO2

PaCO2 22

HCO3- 14

Base Excess

SiO2

• Metabolic Acidosis with partial respiratory compensation

Practice #17

pH 7.49

PaO2

PaCO2 51

HCO3- 29

Base Excess

SiO2

• Metabolic Alkalosis with partial respiratory compensation

Practice #18

pH 7.43

PaO2

PaCO2 31

HCO3- 18

Base Excess

SiO2

• Respiratory Alkalosis with complete/full metabolic compensation

Practice #19

pH 7.29

PaO2

PaCO2 50

HCO3- 15

Base Excess

SiO2

• Respiratory & Metabolic Acidosis with NO respiratory or metabolic compensation

Practice #20

pH 7.25

PaO2

PaCO2 59

HCO3- 15

Base Excess

SiO2

• Respiratory & metabolic acidosis with no respiratory or metabolic compensation

Practice #21

pH 7.40

PaO2

PaCO2 60

HCO3- 35

Base Excess +12

SiO2

• Metabolic Alkalosis with complete/full respiratory compensation

Practice #22

pH 7.40

PaO2

PaCO2 60

HCO3- 35

Base Excess -12

SiO2


respiratory module acid-base disturbances. regulation of acid-base balances normal plasma ph –...

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