37 Questions
What does the Oxy-Hgb Dissociation Curve illustrate?
Trends in O2 binding with Hemoglobin
Which condition leads to a rightward shift in the Oxy-Hgb Dissociation Curve?
Acidosis
What does Base Excess represent?
Amount of acid or alkali that must be added to 1L of blood to return the sample to a pH 7.40
What is the recommended maximum rate for NaHCO3 administration?
1 mEq/kg/hr
What are the effects of IV NaHCO3 administration?
Increased levels of CO2 due to shift in carbonic anhydrase reaction
What does a Base Excess of +2 suggest?
Metabolic alkalosis
What are the systemic effects of acidemia?
Myocardial Depression
What are the factors that cause a leftward shift in the Oxy-Hgb Dissociation Curve?
Alkalosis, Hypothermia
What is the Arrhenius definition of acids and bases?
Acids dissociate to produce hydrogen ions; bases dissociate to produce hydroxyl ions
What is the Henderson-Hasselbalch equation used to describe?
The mathematical relationship of pH due to pKa and solute concentrations
What does the equilibrium constant (K) predict?
The point of equal molar concentrations between product and reactants
What is the pH scale range and its significance?
The pH scale ranges from 1 to 14; 7 is neutral
What does the Lewis approach define acids and bases as?
Acids are acceptors of electrons; bases are donors of electrons
What does the pKa/pKb represent?
The -log of Ka/Kb; lower value indicates a strong acid/base
What is the Boston Approach related to?
Related the Henderson-Hasselbalch equation to clinical practice of predicting acid-base disorders
What does the pH represent?
The negative logarithm of hydrogen ion concentration
What is the goal of an acid-base reaction?
To reach neutralization
What is the primary emphasis of Stewart's Physicochemical Approach in determining pH?
Variables PaCO2, Atot, and SID
What is the Strong Ion Difference (SID) defined as?
Balance of measurable cations and anions
What does the Total Amount of Weak Acid (Atot) include?
Non-bicarbonate buffers like albumin and phosphate
How is the dissociation of water explained?
As an amphiprotic species that acts as an acid or base
What imposes the acid-base load?
Diet, metabolic processes, cellular shifts, and iatrogenic interventions
What are the three primary systems to maintain acid-base balance?
Buffer System, Lungs, and Kidneys
What does chemical buffering involve?
Solutions that resist shifts in pH due to addition of acid or base
What is the primary function of the bicarbonate buffer system?
To resist sudden changes in pH by converting strong bases to weak bases and vice versa
What is the primary method for assessing acid-base disorders?
Arterial blood gas (ABG) analysis
Which condition is characterized by low PaCO2 and high pH?
Respiratory alkalosis
What can help identify metabolic acidosis?
Calculation of the anion gap
What is the measure of the difference between major cations and anions?
Anion gap
What characterizes respiratory acidosis?
High PaCO2 and low pH
What helps identify additional acid-base disorders?
Delta gap
What is characterized by high HCO3 and high pH?
Metabolic alkalosis
What equation helps in assessing hypoxemia?
Alveolar gas equation
What is characterized by low HCO3 and low pH?
Metabolic acidosis
What helps in evaluating hypoxemia-related pathology?
A-a oxygen gradient
What equation can help identify hypoxemia-related issues?
Alveolar gas equation
What is the primary method for assessing acute respiratory derangements?
PaCO2
Study Notes
Understanding Acid-Base Balance in the Body
- S is the solubility coefficient of CO2 = 0.03 Eq
- Acid-base balance concepts introduced by Siggaard/Andersen in the 1950s
- Anion Gap Approach introduced by Emmett/Narins in 1977 to evaluate acid-base balance
- Stewart Model introduced in 1983 based on the law of electroneutrality, dilution, and conservation of mass
- Stewart's Physicochemical Approach emphasizes the role of variables PaCO2, Atot, and SID in determining pH
- Strong Ion Difference (SID) defined as the balance of measurable cations and anions
- Total Amount of Weak Acid (Atot) includes non-bicarbonate buffers like albumin and phosphate
- Dissociation of Water explained as an amphiprotic species that acts as an acid or base
- Acid-base load is imposed via diet, metabolic processes, cellular shifts, and iatrogenic interventions
- Three primary systems to maintain acid-base balance: Buffer System, Lungs, and Kidneys
- Chemical buffering involves solutions that resist shifts in pH due to addition of acid or base
- Bicarbonate buffer system works to resist sudden changes in pH by converting strong bases to weak bases and vice versa
Understanding Acid-Base Disorders
- Acid-base disorders are assessed through arterial blood gas (ABG) analysis
- Differentiating between respiratory and metabolic acid-base disorders is crucial
- Calculation of the anion gap can help identify metabolic acidosis
- Respiratory alkalosis is characterized by low PaCO2 and high pH
- Respiratory acidosis is characterized by high PaCO2 and low pH
- Acute and chronic respiratory derangements have different effects on pH
- Metabolic alkalosis is characterized by high HCO3 and high pH
- Metabolic acidosis is characterized by low HCO3 and low pH
- Anion gap is a measure of the difference between major cations and anions
- The delta gap helps identify additional acid-base disorders
- Alveolar gas equation helps in assessing hypoxemia
- The A-a oxygen gradient is calculated to determine hypoxemia-related pathology
Test your knowledge of acid-base balance and disorders with this quiz. From the Stewart Model to arterial blood gas analysis, challenge yourself with questions on solubility coefficients, anion gap, respiratory and metabolic acid-base disorders, and more.
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