Acid Base Flashcards
What is the pH range for acid-base balance in physiology?
The pH range is tightly regulated between 7.35 - 7.45.
How do changes in relative concentrations of acids and bases affect water’s ability to auto-ionize?
Excess acids (H+) or bases (OH-) can disrupt the auto-ionization of water.
Why is acid-base balance critical for maintaining optimal enzymatic function?
Optimal pH levels support the proper function of enzymes in various physiological processes.
What historical observation in 1831 is associated with acid-base balance?
O’Shaughnessy observed the loss of carbonate of soda in cholera patients, indicating acid-base disturbances.
What does acidemia result from?
Acidemia results from excess production of H+ ions compared to OH- ions.
What causes alkalemia?
Alkalemia arises from excess production of OH- ions compared to hydrogen ions.
How does CO2 enter and leave the body in the context of pH regulation?
CO2 enters and leaves the body through the lungs, playing a role in regulating pH.
In renal regulation of pH, what is the role of the proximal tubule?
The proximal tubule is involved in H+ reabsorption, contributing to pH regulation.
What equation defines acid-base balance and what components does it involve?
The Henderson-Hasselbalch Equation defines pH balance using serum bicarb and PaCO2 levels.
How does water demonstrate amphoteric nature in acid-base interactions?
Water can act as both an acid and a base, accepting or donating protons accordingly.
Provide examples of substances and their behavior as acids or bases in water interactions.
HCl acts as an acid by donating a proton, while KOH acts as a base by receiving a proton.
What determines the acid strength of a substance in water dissociation?
The degree of dissociation in water determines the acid strength of a substance.
What is the significance of electrical neutrality in acid-base balance?
Maintaining electrical neutrality involves balancing negative and positively charged ions for stability.
How does mass conservation contribute to acid-base equilibrium?
Mass conservation ensures a constant quantity of substances, contributing to acid-base equilibrium.
What are the most abundant strong ions in extracellular fluid?
Sodium (Na+) and Chloride (Cl-) are the most abundant strong ions in the extracellular fluid.
How is Strong Ion Difference (SID) calculated?
SID is calculated as the total strong cations minus the strong anions in a solution.
In the extracellular fluid, is the Strong Ion Difference (SID) always positive or negative?
In the extracellular fluid, the SID is always positive.
What role does the Strong Ion Difference (SID) serve as in clinical practice?
SID serves as an independent predictor of pH in clinical practice.
What steps are involved in identifying a disturbance in acid-base balance?
Identify if pH is increased or decreased, then assess changes in PaCO2 and/or HCO3- levels from normal.
What does it indicate if both PaCO2 and HCO3- change in the same direction?
It indicates a primary disorder with secondary compensation in acid-base balance.
What does it suggest if both PaCO2 and HCO3- change in different directions?
It suggests a mixed acid/base disorder in the acid-base balance.
Provide examples of blood gas values indicating acid-base status?
Examples include pH 7.33, PCO2 48, HCO3 26 and pH 7.58, PCO2 35, HCO3 29, among others.
What are the consequences of acidosis on cardiovascular function?
Including impaired contractility, decreased arterial blood pressure, increased dysrhythmia sensitivity, and reduced catecholamine responsiveness.
How does acidosis affect pulmonary function?
It leads to hyperventilation, dyspnea, and respiratory muscle fatigue.
What metabolic consequences are associated with acidosis?
Hyperkalemia, insulin resistance, and inhibition of anaerobic glycolysis are metabolic consequences of acidosis.
What causes an increase in PaCO2 leading to respiratory acidosis?
An acute decrease in alveolar ventilation.
Name conditions that can cause a decrease in pH leading to respiratory acidosis.
Respiratory failure, drug-induced ventilatory depression, permissive hypercapnia, upper airway obstruction, and central ventilation control issues, among others.
What are the causes of acute hypercarbia in respiratory acidosis?
A slow rise in bicarbonate levels, where a PaCO2 increase of 10 mmHg corresponds to a plasma HCO3- increase of 1 mmol/L.
How is chronic hypercarbia characterized in respiratory acidosis?
Associated with a significant rise in bicarbonate levels, where a PaCO2 increase of 10 mmHg leads to a plasma HCO3- increase of 3 mmol/L.
In a clinical scenario with a PaCO2 of 80 mm Hg post-bowel resection, how is hypercapnia classified?
Acute hypercapnia as indicated by the 40 mm Hg higher PaCO2 than normal.
What treatment is essential for managing hypercarbia in respiratory acidosis?
Mechanical ventilation is crucial.
Why is caution advised when reversing chronic hypercarbia?
Excessive bicarbonate can lead to CNS irritability and seizures.
What characterizes metabolic acidosis?
Lowered blood pH indicating an underlying condition with insufficient respiratory compensation.
Name the causes of metabolic acidosis related to acid production.
Increased production of acid, decreased excretion of acid, acid ingestion, and renal/GI bicarbonate losses.
What factors are associated with metabolic acidosis besides acid imbalance?
Alterations in transcellular ion pumps, ionized calcium, and a rightward shift of oxyhemoglobin dissociation curve.
How is compensation calculated for metabolic acidosis with bicarbonate level?
Using the formula: 1.5 x HCO3 - + 8. For example, HCO3 - of 12 mmol/L corresponds to an expected PaCO2 of 26 mm Hg.
What causes normal anion gap acidosis, and how is electrical neutrality maintained?
Causes include sodium chloride infusions, diarrhea, and early renal failure. Electrical neutrality is maintained by sodium balanced by bicarbonate and chloride.
What is the formula for simple anion gap calculation, and what does it measure?
Formula: Na+ - (Cl - + HCO3 - ) = 12 - 14 mEq/L. It measures the anion gap in physiological calculations.
What are common causes of high anion gap acidosis?
Causes include lactic acidosis, ketoacidosis, renal failure, and poisonings that introduce additional acids reducing bicarbonate availability.
What mnemonic can be used to remember causes of anion gap acidosis?
Cyanide, CO, Arsenic, Toluene, Methanol, Metformin, Uremia, DKA, Paraldehyde, Iron, Lactate, Ethylene glycol, Salicylates
What does lactic acidosis serve as a marker for?
Critical illness
How can one differentiate between overproduction and inadequate clearance regarding lactic acidosis?
By assessing the underlying cause, such as anaerobic conditions or aerobic pathways
What is the focus of treatment for ketoacidosis?
Insulin administration and fluid resuscitation
What factors should be considered in treating lactic acidosis?
Improving tissue perfusion, fluid resuscitation, discontinuation of metformin
What treatment approach is suggested in cases related to renal failure?
Consideration of dialysis
Why is the use of sodium bicarbonate in treatment controversial?
Debate surrounds its efficacy and potential adverse effects
When should the use of sodium bicarbonate be considered based on pH levels?
When pH levels are <7.1
What role does sodium bicarbonate play in seeking to correct acidosis?
It reacts with H+ to generate CO2 and may further decrease pH
How can acute pH changes in chronic metabolic acidosis affect tissue oxygenation?
Acute changes can negate the right shift of the curve (Bohr effect) leading to tissue hypoxia
What is the calculation for determining the full correction dose of sodium bicarbonate?
0.3 x base deficit (mmol/L) x weight (kg)
Why is elective surgery advised to be postponed in the presence of acidosis?
To avoid exacerbating the condition and allow for stabilization
How should fluid administration be guided in anesthesia management for acidosis?
Based on hemodynamic monitoring
What aspect of the patient should be closely monitored during anesthesia in the presence of acidosis?
Cardiac function
Why are regular laboratory assessments considered essential in acidosis management?
To track progress, adjust treatment, and ensure patient safety
What is the definition of respiratory alkalosis?
Respiratory alkalosis is characterized by acute increased alveolar ventilation and results in decreased PaCO2 with pH > 7.45.
Name some causes of respiratory alkalosis.
Causes include pregnancy, high altitude, iatrogenic hyperventilation (during perioperative period), and salicylate overdose.
What are the symptoms of respiratory alkalosis?
Symptoms include lightheadedness, visual disturbances, and dizziness.
What are the effects of respiratory alkalosis on calcium binding?
Respiratory alkalosis leads to a greater binding of calcium to albumin.
List some signs of hypocalcemia associated with respiratory alkalosis.
Signs include paresthesia, muscle spasm, cramps, tetany, circumoral numbness, seizures, Trousseau’s sign, and Chvostek’s sign.
Describe the characteristics of metabolic alkalosis.
Metabolic alkalosis is characterized by a marked increase in plasma bicarbonate, usually compensated for by an increase in carbon dioxide.
What are the causes of metabolic alkalosis?
Causes include iatrogenic factors, renal or extrarenal causes, net loss of H+ or net gain of bicarb, and excess citrate.
What is another term for metabolic alkalosis associated with volume status?
Metabolic alkalosis is also known as volume depletion or volume overload alkalosis.
What are some causes of metabolic alkalosis?
Causes include hypovolemia, vomiting, NG suction, diuretic therapy, bicarb administration, and hyperaldosteronism.
What are the symptoms of metabolic alkalosis?
Symptoms include lightheadedness, tetany, and paresthesia.
How is metabolic alkalosis treated based on the underlying cause?
Treatment depends on the cause, with approaches like saline fluid resuscitation for volume depletion, proton pump inhibitors for gastric loss, and addition of K+ sparing diuretics for loop diuretics.
