Acid-Base Disturbances 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 Acid ALKALINE h pH Base = alkaline = h pH Acidic i pH Acid = acidic = i pH

3 Bases 3 Acids 3B = 3A pH = Homeostasis 7.40

4 Bases High 4 Acids 4B = 4A pH = Homeostasis 7.40

2 Bases Low 2 Acids 2B = 2A pH = Homeostasis 7.40

4 Bases (alkaline) 3 Acids (acidic) 4B > 3A pH = High Normal Alkalosis > 7.45

3 Bases (alkaline) 4 Acids (acidosis) 3B < 4A pH = Normal High < 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 h Acid & Normal Base = i pH =Acidosis Normal Acid & h Base = h pH = Alkalosis Normal Acid & i Base = i pH =Acidosis h Acid & Normal Base = i pH =Acidosis i Acid & Normal Base = h pH = Alkalosis

Chemical Buffers The body’s major buffer system is Bicarbonate 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 h HCO3 plasma (base) h pH If the kidneys excrete bicarbonate i HCO3 plasma (base) i pH

Kidneys If the plasma pH is acidic (ipH: A > B) the kidneys will compensate by… Retain / reabsorb bicarbonate (HCO3-) to help restore balance h HCO3- in the blood h serum pH 4A > 3B  4A = 4B

Kidneys If the plasma pH is alkaline (h pH 3A > 4B or 2A > 3B) the kidneys will… Excrete bicarbonate (HCO3-) to help restore balance i HCO3 i pH 2A < 3B  2A = 2B

Kidneys Restoration of a balances pH is called: 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 Increase in respiratory rate h CO2 (acid) i pH Increase in respiratory rate i CO2 (acid) h pH

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

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

Learning Tip Respiratory = Lungs = CO2 = Acid Metabolic = Kidneys = HCO3 = Base

Practice Questions HCO3- : 45 HCO3- : 24 PaCO2: 60 HCO3- : 18 h alkalosis Normal h acidosis i acidosis i alkalosis

Practice Questions HCO3-: 32 PaCO2: 40 HCO3-: 12 PaCO2: 53 PaCO2: 24 h  Alkaline N  Homeostasis i  Acidosis h  Acidosis i  Alkalosis

More practice questions PaCO2: 65 PaCO2: 35 PaCO2: 52 PaCO2: 20 HCO3: 18 HCO3: 24 HCO3: 30 HCO3: 12 h Acidosis Normal i Alkalosis i Acidosis h Alkalosis

Respiratory Acidosis: Characteristics pH < 7.35 i PaCO2 > 45 mmHg Hypercapnia Metabolic Compensation h HCO3- Kidneys reabsorb and retain HCO3

Respiratory Acidosis: Clinical Manifestations Feeling of fullness in the head h 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 h Bicarbonate / HCO3- > 26 mEq/l h Respiratory compensation h CO2 by Hypoventilation

Metabolic Alkalosis: Clinical Manifestations 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 h PaCO2 < 35 mmHg i Metabolic Compensation ↓ HCO3 by The kidney will excrete HCO3

Respiratory Alkalosis: Clinical Manifestations Lightheadedness i concentration i 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 i Bicarbonate - HCO3 < 22 i Respiratory Compensation i 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 Respiratory alkalosis 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 h PaCO2 Hypoventilation i 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 Label the pH, PaCO2 & HCO3- Serum pH > 7.4 Alkalosis Serum pH < 7.4 Acidosis Serum pH = 7.4 Homeostasis

Steps to Blood Gas Analysis Label the PaCO2 & HCO3- PaCO2 h  Acidosis PaCO2 i  Alkalosis HCO3- h  HCO3- i 

Steps to Blood Gas Analysis 2. Find the Cause of the acid-base disturbance pH > 7.4 Alkalosis h If the PaCO2 is < 40 i = respiratory alkalosis If the HCO3- is > 24 h = metabolic alkalosis pH < 7.4 Acidosis i If the PaCO2 > 40 h = respiratory acidosis If the HCO3- is < 24 i = metabolic acidosis

Steps to Blood Gas Analysis 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 Metabolic Alkalosis with NO respiratory compensation

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 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 Metabolic Alkalosis with NO respiratory compensation

Practice #13 pH 7.14 PaO2 80 PaCO2 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 Metabolic Alkalosis with NO respiratory compensation

Practice #15 pH 7.35 PaO2 PaCO2 58 HCO3- 31 Base Excess SiO2 Respiratory acidosis with complete/full metabolic compensation

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 acidosis with complete/full metabolic compensation