The decrease in carbonic acid seen in hyperventilation is called as

RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Applied Physiology

Easy

Appeared in: RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Explanation

Hyperventilation is characterized by rapid, deep breathing, which causes excessive exhalation of carbon dioxide (CO₂).
In the blood, CO₂ combines with water to form carbonic acid (H₂CO₃). A decrease in CO₂ (hypocapnia) directly reduces the level of carbonic acid.
Since carbonic acid is a volatile acid, its reduction causes the blood pH to rise above the normal range of 7.35-7.45, leading to a state of alkalosis.
Because the root cause is a respiratory issue (hyperventilation), the condition is classified as Respiratory Alkalosis.

Option A: Metabolic alkalosis is incorrect because it results from a primary increase in bicarbonate (HCO₃⁻) or a loss of non-volatile acids, such as from vomiting or diuretic use. It is a metabolic issue, not a respiratory one.
Option C: Metabolic acidosis is incorrect because it involves a primary decrease in bicarbonate (HCO₃⁻) or an increase in non-volatile acids, leading to a low pH. Hyperventilation is actually a compensatory mechanism for metabolic acidosis, not the cause.
Option D: Respiratory acidosis is the opposite condition. It is caused by hypoventilation (inadequate breathing), which leads to the retention of CO₂ and an increase in carbonic acid, causing the pH to drop.

Visual 1: Diagram: Illustrating the chemical equation CO₂ + H₂O <=> H₂CO₃ <=> H⁺ + HCO₃⁻, showing how a decrease in CO₂ shifts the equilibrium to the left, reducing H⁺ ions and increasing pH.
Visual 2: Flowchart: Showing the pathophysiology of Respiratory Alkalosis starting from the cause (e.g., anxiety, hypoxia) -> Hyperventilation -> Decreased PaCO₂ -> Increased pH.
Visual 3: Chart: Comparing the four types of acid-base imbalances (Respiratory/Metabolic Acidosis/Alkalosis) with their primary change (PaCO₂ or HCO₃⁻) and compensatory response.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Acid-Base Imbalance: Respiratory Alkalosis as background academic context rather than a clinical decision trigger.
Nurses must be able to quickly identify the signs of respiratory alkalosis (e.g., lightheadedness, tingling in fingers and toes, tachypnea) and intervene to prevent complications like tetany or seizures.
A key nursing intervention is managing the underlying cause, such as providing reassurance to an anxious patient or correcting hypoxia, rather than just treating the breathing pattern.
What if? If the patient was hypoventilating due to an opioid overdose instead of hyperventilating, the condition would be Respiratory Acidosis. The priority nursing action would be to support ventilation and administer naloxone as prescribed.

How to Approach the Question

First, identify the key terms in the question: 'hyperventilation' and 'decrease in carbonic acid'.
Recall the relationship between breathing, carbon dioxide (CO₂), and carbonic acid. Hyperventilation means breathing off excess CO₂.
Understand that CO₂ is the source of carbonic acid in the blood. Therefore, a decrease in CO₂ leads to a decrease in acid.
A decrease in acid leads to a more alkaline state (alkalosis).
Since the cause is related to breathing (ventilation), it is a 'respiratory' issue.
Combine these parts: 'Respiratory' + 'Alkalosis' = Respiratory Alkalosis.

Concept Tested & Keywords

QzhGQgrftu_riWTwyV_gkT