Podcast
Questions and Answers
What occurs to the pH in a patient experiencing respiratory acidosis due to asthma?
What occurs to the pH in a patient experiencing respiratory acidosis due to asthma?
- pH decreases due to elevated carbon dioxide levels (correct)
- pH increases due to elevated carbon dioxide levels
- pH remains unchanged during acute episodes
- pH decreases due to decreased carbon dioxide levels
In the context of acid-base balance, which statement correctly defines alkalosis?
In the context of acid-base balance, which statement correctly defines alkalosis?
- A condition characterized by an excess of carbonic acid
- A condition where the pH is less than 7.36
- A condition where the body compensates by increasing respiratory rate
- A condition due to accumulation of base or loss of acid (correct)
Which physiological response helps compensate for a pH disturbance caused by respiratory failure?
Which physiological response helps compensate for a pH disturbance caused by respiratory failure?
- Increased respiratory rate to remove COâ‚‚ (correct)
- Decreased production of lactic acid
- Increased renal excretion of bicarbonate
- Decreased oxygen delivery to tissues
What is likely indicated by a moderate asthma attack in terms of arterial blood gases (ABGs)?
What is likely indicated by a moderate asthma attack in terms of arterial blood gases (ABGs)?
What does the term 'hypercapnia' refer to in the context of respiratory acidosis?
What does the term 'hypercapnia' refer to in the context of respiratory acidosis?
Which condition would most likely prevent the correction of acidosis by the respiratory system in an asthma patient?
Which condition would most likely prevent the correction of acidosis by the respiratory system in an asthma patient?
When interpreting ABGs, what finding is typically associated with severe asthma exacerbation?
When interpreting ABGs, what finding is typically associated with severe asthma exacerbation?
What is the typical magnitude of change in the bicarbonate concentration (HCO₃-) during acute respiratory acidosis due to asthma?
What is the typical magnitude of change in the bicarbonate concentration (HCO₃-) during acute respiratory acidosis due to asthma?
What is the primary disturbance in respiratory acidosis?
What is the primary disturbance in respiratory acidosis?
If a patient presents with a pH of 7.28 and a PaCOâ‚‚ of 50 mmHg, what is the probable interpretation?
If a patient presents with a pH of 7.28 and a PaCOâ‚‚ of 50 mmHg, what is the probable interpretation?
How does the respiratory system compensate for metabolic acidosis?
How does the respiratory system compensate for metabolic acidosis?
What indicates adequate compensation for an acid-base disturbance?
What indicates adequate compensation for an acid-base disturbance?
In which condition would you expect a pH greater than 7.45?
In which condition would you expect a pH greater than 7.45?
What is the expected change in HCO₃- levels during respiratory alkalosis?
What is the expected change in HCO₃- levels during respiratory alkalosis?
Which ABG result would indicate a compensated respiratory alkalosis?
Which ABG result would indicate a compensated respiratory alkalosis?
What is the likely interpretation of ABGs showing a pH of 7.36, PaCO₂ of 43, and HCO₃ of 22?
What is the likely interpretation of ABGs showing a pH of 7.36, PaCO₂ of 43, and HCO₃ of 22?
What is the primary physiological response to an acute respiratory acidosis in terms of compensation?
What is the primary physiological response to an acute respiratory acidosis in terms of compensation?
In the context of chronic bronchitis, what ABG profile is indicative of compensated respiratory acidosis?
In the context of chronic bronchitis, what ABG profile is indicative of compensated respiratory acidosis?
What term best describes the condition when pH is alkalotic, PaCO₂ is low, and HCO₃ is normal?
What term best describes the condition when pH is alkalotic, PaCO₂ is low, and HCO₃ is normal?
Which statement about the compensation mechanisms in respiratory acidosis is correct?
Which statement about the compensation mechanisms in respiratory acidosis is correct?
In a patient experiencing hyperventilation, what would you expect their ABG results to reflect?
In a patient experiencing hyperventilation, what would you expect their ABG results to reflect?
Which ABG value combination is associated with uncompensated metabolic acidosis?
Which ABG value combination is associated with uncompensated metabolic acidosis?
How do the kidneys compensate in a patient with chronic respiratory acidosis?
How do the kidneys compensate in a patient with chronic respiratory acidosis?
What condition may result in a low pH, normal HCO₃, and low PaCO₂?
What condition may result in a low pH, normal HCO₃, and low PaCO₂?
Flashcards
Acidosis
Acidosis
A condition where the body's pH is lower than 7.36, indicating an excess of acid or a deficiency of base.
Alkalosis
Alkalosis
A condition where the body's pH is higher than 7.44, indicating an excess of base or a deficiency of acid.
Respiratory Acid-Base Disturbance
Respiratory Acid-Base Disturbance
An acid-base disturbance primarily caused by problems with breathing or alveolar ventilation.
Metabolic Acid-Base Disturbance
Metabolic Acid-Base Disturbance
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Respiratory Acidosis
Respiratory Acidosis
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Respiratory Alkalosis
Respiratory Alkalosis
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Partial Pressure of Carbon Dioxide (PaCOâ‚‚)
Partial Pressure of Carbon Dioxide (PaCOâ‚‚)
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Asthma
Asthma
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Metabolic Acidosis
Metabolic Acidosis
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Metabolic Alkalosis
Metabolic Alkalosis
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Compensation
Compensation
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Uncompensated Acidosis/Alkalosis
Uncompensated Acidosis/Alkalosis
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Partially Compensated Acidosis/Alkalosis
Partially Compensated Acidosis/Alkalosis
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Fully Compensated Acidosis/Alkalosis
Fully Compensated Acidosis/Alkalosis
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Uncompensated Metabolic Acidosis
Uncompensated Metabolic Acidosis
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Compensated Metabolic Acidosis
Compensated Metabolic Acidosis
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Study Notes
Learning Objectives
- Students should be able to describe compensation for pH disturbances by the respiratory system
- Students should be able to explain compensation for pH disturbances due to respiratory diseases
- Students should be able to describe respiratory acidosis and respiratory alkalosis
- Students should be able to interpret ABGs (Arterial Blood Gases) in various clinical disorders
Patient Presentation
- Shortness of breath
- Chest tightness
- Trouble sleeping due to shortness of breath and coughing
- Whistling or wheezing sound when exhaling
Asthma and the Bronchial Tubes
- Normal bronchial tubes have relaxed smooth muscles
- Inflamed bronchial tubes (asthma) have tightened smooth muscles, swelling, and mucus buildup in the airways
ABGs in Acute Asthma
- Mild: Increased pH, increased PaO2, decreased PaCO2, increased HCO3
- Moderate: Decreased pH, decreased PaO2, decreased PaCO2, increased HCO3
- Severe: Decreased pH, decreased PaO2, increased PaCO2, decreased HCO3
Asthma and Respiratory Acidosis
- Cellular respiration continuously produces CO2
- Asthma reduces the lungs' ability to remove CO2
- CO2 accumulates, leading to increased PaCO2 (hypercapnia)
- The HCO3-/PaCO2 ratio decreases
- pH decreases
Acid-Base Imbalances
- Acidosis: pH below 7.4, [HCO3]< 24 mEq/L, Pco2 > 40 mmHg
- Alkalosis: pH above 7.4, [HCO3] > 24 mEq/L, Pco2 < 40 mmHg
- Metabolic acidosis: Causes decreased bicarbonate levels
- Respiratory acidosis: Causes increased CO2 levels
- Metabolic alkalosis: Causes increased bicarbonate levels
- Respiratory alkalosis: Causes decreased CO2 levels
- Compensation: Responses to primary acid-base disorders to restore pH to normal
Normal Arterial Blood Gas Values
- pH: 7.35-7.45
- PaCO2: 35-45 mmHg
- PaO2: 80-100 mmHg
- HCO3-: 22-26 mEq/L
Body and pH Homeostasis
- The body tightly controls pH
- Extracellular fluid pH is usually 7.4
- Blood pH is 7.35-7.45
- Levels below 6.8 or above 8.0 are life-threatening
Acid-Base Balance
- pH scale 6.8 - 8.0
- Normal range 7.35-7.45
Acid-Base Disturbances
- Acidosis: due to acid accumulation or base loss
- Alkalosis: due to base accumulation or acid loss
- Respiratory acidosis: ventilation dysfunction
- Metabolic acidosis: gain or loss of non-carbonic acid
- Simple disorders: single primary event and compensation
- Mixed disorders: multiple primary events
Definitions of Acid-Base Terms
- Acidemia: Low blood pH (< 7.36)
- Alkalemia: High blood pH (> 7.44)
- Hypocapnia: Low PaCO2 (< 36 mmHg)
- Hypercapnia: High PaCO2 (> 44 mmHg)
- Metabolic acidosis: Decrease in plasma bicarbonate
- Metabolic alkalosis: Increase in plasma bicarbonate
- Respiratory acidosis: Increased PaCO2
- Respiratory alkalosis: Decreased PaCO2
- Compensatory Processes: Responses correcting primary disorders
Regulation of Blood pH
- The body maintains blood pH at 7.35-7.45 using three systems
- Buffers, respiratory regulation, renal regulation
Acid-Base Buffer Systems
- Buffers respond quickly to minor pH changes
- Respiratory system regulates CO2 levels within minutes
- Renal system regulates bicarbonate levels in hours to days
Respiratory Acidosis
- Symptoms: breathing difficulties, restlessness, rapid shallow breathing, lethargy and disorientation, drowsiness, dizziness
- Causes: pneumonia, emphysema, asthma, chronic lung disease, pulmonary edema, respiratory depression
- Elevated PaCO2, normal or near-normal blood pH, elevated HCO3
Causes of Respiratory Acidosis
- Airway obstruction
- Lung diseases
- Respiratory center depression
- Extrapulmonary thoracic diseases
- Neural diseases
Causes of Acidosis (Hypoventilation)
- Drug overdose
- Pulmonary edema
- COPD
- Chest trauma
- Neuromuscular disease
Decreased Ventilation Mechanism
- Decreasing ventilation increase arterial Pco2
- Increasing plasma CO2 lower blood pH
- Chemoreceptors respond and increase ventilation
Compensation
- Metabolic compensation in response to respiratory problem
- Respiratory compensation in response to metabolic problem
- Compensation mechanisms are slower or faster
Causes of Alkalosis (Hyperventilation)
- Anxiety
- High altitudes
- Initial stages of pulmonary emboli (blood clot in lungs)
- Hypoxia (lack of oxygen)
- Pregnancy
- Fever
Causes of Alkalosis
- Loss of gastric juices
- Overuse of antacids
- Potassium wasting diuretics
Compensation Speed
- Respiratory compensation is fast (12-24 hours)
- Metabolic compensation is slow (5-7 days)
Chemical Buffers
- On-scene, handle minor acid-base imbalances
Respiratory Compensation
- Affects CO2 regulation quickly
Renal Compensation
- Regulates bicarbonate to combat hydrogen losses
- Slowest compensation (up to 5 days)
Arterial Blood Gas (ABG) Analysis Steps
- Step 0: Is the ABG authentic?
- Step 1: Determine if acidemia or alkalemia
- Step 2: Identify if respiratory or metabolic
- Step 3: Determine if acute or chronic (if respiratory)
- Step 4: Assess compensation adequacy
- Step 5: Identify if metabolic etiology is anion gap
- Step 6: Further evaluate high-gap metabolic acidosis
Interpreting an ABG Strip
- Step 1: Assess the pH
- Step 2: Assess the PaCO2 level
- Step 3: Assess the HCO3 value
Identifying Primary Process (Diagram)
- Diagram helps visualize if acidemia or alkalemia and associated causes
ABG Analysis Table (Primary and Secondary Responses
- Table shows pH's, [H+] levels and primary vs secondary responses
Case examples (ABGs Practice Problems)
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