Respiratory Acidosis and Alkalosis Quiz

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Questions and Answers

What is the primary cause of respiratory alkalosis as observed in the case scenario?

Increased carbonic acid

Increased bicarbonate

Decreased carbonic acid (correct)

Decreased bicarbonate

Which of the following best explains the mechanism by which hyperventilation leads to a respiratory alkalosis?

Increased respiratory rate without changes in bicarbonate

Increased CO2 retention

Increased bicarbonate reabsorption

Decreased CO2 levels in the blood (correct)

In analyzing arterial blood gases (ABGs), which value indicates a respiratory alkalosis condition?

HCO3- greater than 26 mEq/L

HCO3- less than 22 mEq/L

PaCO2 less than 34 mm Hg (correct)

pH less than 7.35

Identify the role of bicarbonate in the regulation of blood pH during respiratory disturbances.

Bicarbonate serves as a buffer to maintain normal pH levels. Signup and view all the answers

Which of the following statements about the Henderson-Hasselbalch equation is true?

It describes the relationship between pH, bicarbonate, and carbonic acid. Signup and view all the answers

What is the expected HCO3- level in a patient with uncontrolled hyperventilation?

Below 22 mEq/L Signup and view all the answers

In cases of respiratory acidosis, what compensatory response can be expected in the kidneys?

Increased bicarbonate reabsorption Signup and view all the answers

Which of the following clinical signs might be observed in a patient experiencing respiratory alkalosis?

Hyperventilation Signup and view all the answers

What factor primarily influences the level of arterial pCO₂ in a healthy individual?

The rate of carbon dioxide production and alveolar ventilation Signup and view all the answers

In a patient with respiratory acidosis, what is the primary physiological consequence of hypoventilation?

Increased blood carbon dioxide concentration Signup and view all the answers

When analyzing arterial blood gases (ABGs) in a patient with acute respiratory acidosis, which pH measurement signifies the condition?

pH < 7.3 Signup and view all the answers

Which of the following mechanisms can lead to increased arterial pCO₂ levels?

Excess CO₂ in the inspired air Signup and view all the answers

Which condition is a common cause of respiratory acidosis due to decreased alveolar ventilation?

Bronchospasm during an asthma attack Signup and view all the answers

What arterial pH level would indicate acidemia in a patient experiencing respiratory acidosis?

pH 7.30 Signup and view all the answers

Which of the following is NOT a common cause of respiratory acidosis?

Severe hyperventilation Signup and view all the answers

In the context of respiratory disturbances, which of the following statements is true regarding primary respiratory acidosis?

Acidosis refers to a disorder that lowers tissue pH to less than 7.35. Signup and view all the answers

What role do chemoreceptors play in respiratory control?

They detect changes in blood pH, PaO2, and PaCO2. Signup and view all the answers

Which of the following situations describes fully compensated respiratory acidosis?

pH remains within normal range while CO2 is elevated. Signup and view all the answers

Which calculation is used to estimate expected PaCO2 compensation in metabolic acidosis?

PaCO2 = HCO3 X 1.5 + 8 Signup and view all the answers

In a patient with respiratory alkalosis due to hyperventilation, which ABG finding is expected?

Increased pH and decreased PaCO2. Signup and view all the answers

When assessing a patient with respiratory acidosis, which ABG value indicates uncompensated respiratory acidosis?

pH < 7.35, HCO3 normal, CO2 high. Signup and view all the answers

What physiological response occurs in the renal system during respiratory disturbances?

The kidneys retain bicarbonate to raise pH. Signup and view all the answers

What is a significant risk in patients with severe asthma in relation to pH balance?

Uncompensated respiratory acidosis due to hypoventilation. Signup and view all the answers

What blood gas analysis finding would suggest fully compensated respiratory alkalosis?

Normal pH, low HCO3, low CO2. Signup and view all the answers

Study Notes

Case Scenario

A 19-year-old female medical student presented to the emergency room (ER) with shortness of breath, dizziness, lightheadedness, confusion, and heart palpitations.
Her history revealed she had been enjoying herself prior to exams, and the prospect of studying the entire course caused severe anxiety and a panic attack.
Examination revealed rapid, deep, uncontrolled breathing (hyperventilation) and a dry mouth.

ABG Results

pH: 7.55 (Normal: 7.35 - 7.45)
PaCO2: 30 mm Hg (Normal: 34 - 44 mm Hg)
HCO3-: 18 mEq/liter (Normal: 22 - 26 mEq/liter)

Conclusion

The results indicate respiratory alkalosis.

Learning Objectives

Respiratory Acidosis:
- Causes
- Investigation (ABG)
- Compensation (ABG)
Respiratory Alkalosis:
- Causes
- Investigation (ABG)
- Compensation (ABG)

Henderson-Hasselbalch Equation

Describes pH derivation as a measure of acidity in biological and chemical systems.
Useful for estimating the pH of a buffer solution.
7.4 = 6.1 + log₁₀(20)

Respiratory pH Disturbances

Acid-base disorders are classified as:
- Acidosis (low pH)
  - Metabolic
  - Respiratory
- Alkalosis (high pH)
  - Metabolic
  - Respiratory

The Four Primary Acid-Base Disorders

Conditions, Primary Disorder, and Compensation are details in the table from the slides
The table shows the relationship between pH, and HCO3 and pCO2

Causes of Respiratory Acidosis

Hypoventilation (e.g., asthma, COPD, narcotic poisoning)
Airway obstruction
Drug overdose
Chest trauma
Pulmonary edema
Neuromuscular disease

Acute Respiratory Acidosis

Elevated PaCO2 (greater than 6.3 kPa or 45 mm Hg) and accompanying acidemia (pH < 7.36).
Causes include: central respiratory depression, neuromuscular disorders, and airway obstruction.

Symptoms of Respiratory Acidosis

Initial signs include headache, anxiety, blurred vision, restlessness.
Further symptoms can include sleepiness, tremors, delirium.
Neurological manifestations depend on the degree of hypercapnia, rapidity of development, severity of acidemia, and hypoxemia.
Central, muscular, intestinal signs, detailed in table from slides

Compensation Mechanisms

Chemical buffers initially respond to small acid/base changes
Respiratory systems respond within minutes to moderate shifts, through retention or elimination of CO2.
Renal systems respond in hours to more severe shifts by regulating bicarbonate.

Compensation of Respiratory Acidosis

Pulmonary and renal systems compensate for each other returning pH to normal levels.
Lungs compensate for metabolic disturbances by altering PaCO2 levels through hyper/hypoventilation.
Kidneys compensate by altering HCO3- levels by reabsorbing, retaining or excreting it.

Regulation of Respiration

To maintain normal PO₂ and PCO₂ levels in arterial blood.
Respiratory control involves three key elements: sensors, central controller, and effectors.

Respiratory Alkalosis

Acid-base disturbance initiated by a reduction in PaCO2, caused by excessive loss of CO2 through hyperventilation.
Hypocapnia occurs when the rate of CO2 output from the lungs exceeds CO2 production.

Causes of Respiratory Alkalosis

Anxiety
Hypoxia
High altitude
Pregnancy
Fever
Mechanical ventilation

Symptoms of Respiratory Alkalosis

Seizures, deep rapid breathing, hyperventilation, tachycardia, low blood pressure, abnormal heart rhythm (hypokalemia), tingling and numbness
Lethargy, confusion, lightheadedness, nausea and vomiting, further detailed in table from slides.

Hypokalemia

Low potassium levels (less than 3.5 mEq/L) impact nerve and muscle cell function, especially those in the heart.
Signs include tiredness, leg cramps, weakness, constipation, abnormal heart rhythms which may cause cardiac arrest.

ABG Interpretation (Table)

Table showing relationships among ABG components (pH, PaCO2, HCO3)

Compensation of Respiratory Alkalosis

Describes expected outcomes, including metabolic compensation, detailed in the table

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Description

Test your understanding of respiratory acidosis and alkalosis with this quiz. It covers the causes, investigations, and compensatory mechanisms, along with a case scenario involving a medical student. Dive into the biochemical principles with the Henderson-Hasselbalch equation.