1
CHEMISTRY ACID & BASE BALANCE
STUDY GUIDE TIPS 2026-27
LATEST VERSION
Acid-Base Balance
- Acid—is a substance that releases hydrogen ions (H+)
• Gives H+
- Bases or alkalis—have a low hydrogen ion concentration and can accept hydrogen ions
in solution
• Receives the H+
- pH: reflects the hydrogen ion concentration of the solution
• 7.4 is perfect number (releasing/ holding onto H+ & making bicarb, CO2)
- H20 + CO2 <—> H2HCO3<—> H + HC03
• Co2 is controlled via lungs
• Hco3 is controlled by kidneys
• Increase co2 = high acid
• Decrease co2= low acid
- Henderson-Hasselbalch equation
pH Balance
- Body cells are extremely sensitive to their environment
- Slight changes in pH can affect normal cell functioning
- pH refers to the measurement of relative balance between acids and bases in solution
- CO2 reflects lung, HCO3 - reflects kidneys
• Only one lung problem at the time
• Multiple metabolic problems at the time possible
• HCO3 either lost— or mixed with H+
- Three types of solutions:
• Neutral
• Acid
• Alkalotic
How do we lose HCO3 or CO2 ?
- HCO3- lost either by the combination of bicarb to the proton of a conjugate base or
lost either in the urine or the stool (GI = diarrhea)
- CO2 by respiration
o Using bicarb (bases receive h+)
o Or losing by ingesting acid (coffee)
Acid Solution
- As acid is added to solution, pH will go down
- Acids denote H+
- pH<7.00
,2
Alkalotic Solution
- As bases are added to solution pH will go up
- Bases accept H+
- pH>7.00
Normal pH of arterial blood
- Human blood is considered slightly alkalotic
- normal pH is between 7.35-7.45
• < 7.35 = ACID
• >7.45 = ALK
- Human blood normally maintains ratio of 1 acid to 20 bases
- Primary acid is CO2
- Primary base is HCO3
Regulation of Acid-Base Balance
- Buffers Systems
• EX: sodium bicarb
• Neutralizing excess acids or bases
• Prevent excessive changes in pH by removing or releasing hydrogen ions
• Bicarbonate-Carbonic Acid Buffer System
• MOST IMPORTANT
• Phosphate Buffer System
• Protein Buffers
- Respiratory System
• Eliminating or retaining CO2 by the lungs also regulates acid-base balance
• Holding onto via lowering respiratory rate
• Low RR = increase C02 = less acid
• Releasing it via increasing respiratory rate
• High RR= decrease CO2 = more acid
• More co2 = more acid
• CO2 + H2O H2CO3 (carbonic acid)
• The respond is rapid, occur within minutes by altering the rate and depth
of respiration
• Carbon Dioxide is a powerful stimulator of the respiratory system
• PaC02 represents partial pressure of carbon dioxide in arterial blood.
• The normal PaCo2 is 35 to 45 mm Hg
• <35 = less carbonic acid = alkalosis (fast rr)
• >45 = more carbonic acid = acidosis (low rr)
• Increasing ventilation increases pH by eliminating C02
• Decreasing ventilation decreases pH by retaining C02.
• An acute rise in PC02 is a powerful stimulant to respiration
• PaO2 is the partial pressure of oxygen in the plasma.
• PaO2 also influences respiration, but it’s effect is much less effective than that
of the PaC02.
• The normal PaO2 is 80 to 100 mm Hg.
• <60 IS CRTICALL
,3
• Prep for intubation
- Renal system (METABOLIC)
• Excreting or retaining acids and bases
• They are the ultimate long-term regulator of acid-base balance
• They are slower to respond, but their response is more permanent and selective
• Maintain acid-base balance by excreting or conserving bicarbonate and
hydrogen ions
• When pH decreases, H+ ions are excreted, and bicarbonate acid ions
are formed and retained.
• When pH increases, H+ are retained, and bicarbonate acids are excreted
• Normal serum bicarbonate: 21 to 28 mEq/L
• <21 = alkalosis
• >28 = acidosis
Acid-Base & Potassium Imbalances
- Acidosis
• H+ diffuses into cells and drives out K+, elevating K+ concentration in ECF
• CAUTION FOR HYPERKALEMIA
- Alkalosis
• H+ diffuses out of cells and K+ diffuses in
• CAUTION FOR HYPOKALEMIA
PH = HCO3-
6 Acid-Base Disturbances
- Respiratory Acidosis Acute/Chronic
PCO2 +
- Respiratory Alkalosis Acute/Chronic
- Metabolic Acidosis
- Metabolic Alkalosis
Respiratory Acidosis (Carbonic Acid Excess)
- Results from alveolar hypoventilation
- INCREASE CO2
- PaCO2>45 and pH<7.35
- Clinical causes:
• Depression of the central respiratory centers
• Effects of residual anesthetic agents
• Oversedation with narcotics or sedatives (OPIOIDS PT)
• Compression on medullary centers
• Hypothermia
• Interference with muscles of respiration
• Residual effects of neuromuscular blocking agents
• Neuromuscular disease: myasthenia gravis and poliomyelitis
• Brainstem injury
• Pain with splinting
• Tight chest binders and dressings
• Obesity
• Airway obstruction
, 4
• Excessive secretions
• Aspiration
• Relaxation of the tongue
• Edema of pharyngeal soft tissues
• Endotracheal tube mispositioned in single bronchus
• Kinking of ET tube
• Lung disease
• COPD chronic acidosis
• Pulmonary fibrosis
• Atelectasis and pneumonia
• PE / Asthma attack when they start to crash (res. Failure) they become
acidosis in beginning stages they are alkalosis
• Inadequate mechanical ventilation support
Respiratory Acidosis Nursing Interventions”
- Monitor Respiratory distress, 02, vitals
- Semi fowlers position
- Bronchodilators
- Heparin for PE
- Intubation!!
- Respiratory failure hypercapnia PREP FOR INTUBATION
+ CRASH CART + MECHANICAL VENTILATION
• paCO2 > 50
• pH <7.35
CHEMISTRY ACID & BASE BALANCE
STUDY GUIDE TIPS 2026-27
LATEST VERSION
Acid-Base Balance
- Acid—is a substance that releases hydrogen ions (H+)
• Gives H+
- Bases or alkalis—have a low hydrogen ion concentration and can accept hydrogen ions
in solution
• Receives the H+
- pH: reflects the hydrogen ion concentration of the solution
• 7.4 is perfect number (releasing/ holding onto H+ & making bicarb, CO2)
- H20 + CO2 <—> H2HCO3<—> H + HC03
• Co2 is controlled via lungs
• Hco3 is controlled by kidneys
• Increase co2 = high acid
• Decrease co2= low acid
- Henderson-Hasselbalch equation
pH Balance
- Body cells are extremely sensitive to their environment
- Slight changes in pH can affect normal cell functioning
- pH refers to the measurement of relative balance between acids and bases in solution
- CO2 reflects lung, HCO3 - reflects kidneys
• Only one lung problem at the time
• Multiple metabolic problems at the time possible
• HCO3 either lost— or mixed with H+
- Three types of solutions:
• Neutral
• Acid
• Alkalotic
How do we lose HCO3 or CO2 ?
- HCO3- lost either by the combination of bicarb to the proton of a conjugate base or
lost either in the urine or the stool (GI = diarrhea)
- CO2 by respiration
o Using bicarb (bases receive h+)
o Or losing by ingesting acid (coffee)
Acid Solution
- As acid is added to solution, pH will go down
- Acids denote H+
- pH<7.00
,2
Alkalotic Solution
- As bases are added to solution pH will go up
- Bases accept H+
- pH>7.00
Normal pH of arterial blood
- Human blood is considered slightly alkalotic
- normal pH is between 7.35-7.45
• < 7.35 = ACID
• >7.45 = ALK
- Human blood normally maintains ratio of 1 acid to 20 bases
- Primary acid is CO2
- Primary base is HCO3
Regulation of Acid-Base Balance
- Buffers Systems
• EX: sodium bicarb
• Neutralizing excess acids or bases
• Prevent excessive changes in pH by removing or releasing hydrogen ions
• Bicarbonate-Carbonic Acid Buffer System
• MOST IMPORTANT
• Phosphate Buffer System
• Protein Buffers
- Respiratory System
• Eliminating or retaining CO2 by the lungs also regulates acid-base balance
• Holding onto via lowering respiratory rate
• Low RR = increase C02 = less acid
• Releasing it via increasing respiratory rate
• High RR= decrease CO2 = more acid
• More co2 = more acid
• CO2 + H2O H2CO3 (carbonic acid)
• The respond is rapid, occur within minutes by altering the rate and depth
of respiration
• Carbon Dioxide is a powerful stimulator of the respiratory system
• PaC02 represents partial pressure of carbon dioxide in arterial blood.
• The normal PaCo2 is 35 to 45 mm Hg
• <35 = less carbonic acid = alkalosis (fast rr)
• >45 = more carbonic acid = acidosis (low rr)
• Increasing ventilation increases pH by eliminating C02
• Decreasing ventilation decreases pH by retaining C02.
• An acute rise in PC02 is a powerful stimulant to respiration
• PaO2 is the partial pressure of oxygen in the plasma.
• PaO2 also influences respiration, but it’s effect is much less effective than that
of the PaC02.
• The normal PaO2 is 80 to 100 mm Hg.
• <60 IS CRTICALL
,3
• Prep for intubation
- Renal system (METABOLIC)
• Excreting or retaining acids and bases
• They are the ultimate long-term regulator of acid-base balance
• They are slower to respond, but their response is more permanent and selective
• Maintain acid-base balance by excreting or conserving bicarbonate and
hydrogen ions
• When pH decreases, H+ ions are excreted, and bicarbonate acid ions
are formed and retained.
• When pH increases, H+ are retained, and bicarbonate acids are excreted
• Normal serum bicarbonate: 21 to 28 mEq/L
• <21 = alkalosis
• >28 = acidosis
Acid-Base & Potassium Imbalances
- Acidosis
• H+ diffuses into cells and drives out K+, elevating K+ concentration in ECF
• CAUTION FOR HYPERKALEMIA
- Alkalosis
• H+ diffuses out of cells and K+ diffuses in
• CAUTION FOR HYPOKALEMIA
PH = HCO3-
6 Acid-Base Disturbances
- Respiratory Acidosis Acute/Chronic
PCO2 +
- Respiratory Alkalosis Acute/Chronic
- Metabolic Acidosis
- Metabolic Alkalosis
Respiratory Acidosis (Carbonic Acid Excess)
- Results from alveolar hypoventilation
- INCREASE CO2
- PaCO2>45 and pH<7.35
- Clinical causes:
• Depression of the central respiratory centers
• Effects of residual anesthetic agents
• Oversedation with narcotics or sedatives (OPIOIDS PT)
• Compression on medullary centers
• Hypothermia
• Interference with muscles of respiration
• Residual effects of neuromuscular blocking agents
• Neuromuscular disease: myasthenia gravis and poliomyelitis
• Brainstem injury
• Pain with splinting
• Tight chest binders and dressings
• Obesity
• Airway obstruction
, 4
• Excessive secretions
• Aspiration
• Relaxation of the tongue
• Edema of pharyngeal soft tissues
• Endotracheal tube mispositioned in single bronchus
• Kinking of ET tube
• Lung disease
• COPD chronic acidosis
• Pulmonary fibrosis
• Atelectasis and pneumonia
• PE / Asthma attack when they start to crash (res. Failure) they become
acidosis in beginning stages they are alkalosis
• Inadequate mechanical ventilation support
Respiratory Acidosis Nursing Interventions”
- Monitor Respiratory distress, 02, vitals
- Semi fowlers position
- Bronchodilators
- Heparin for PE
- Intubation!!
- Respiratory failure hypercapnia PREP FOR INTUBATION
+ CRASH CART + MECHANICAL VENTILATION
• paCO2 > 50
• pH <7.35
