Related Experiment Video
Updated: Aug 9, 2026
07:52
Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Published on: January 30, 2011
Acid-base response to chronic hypocapnia in man
Bulletin Europeen De Physiopathologie Respiratoire
|September 1, 1977
Summary
This study defines the human response to chronic hypocapnia, showing a linear relationship between carbon dioxide tension and arterial blood hydrogen ion concentration. These findings help identify other acid-base disorders in patients with low carbon dioxide levels.
Area of Science:
- Physiology
- Acid-Base Balance
- Respiratory Medicine
Background:
- Understanding chronic hypocapnia is crucial for managing acid-base disorders.
- Previous research has established responses to chronic hypercapnia.
Purpose of the Study:
- To define the physiological response to chronic hypocapnia in humans.
- To establish reference bands for hydrogen ion and bicarbonate concentrations in chronic hypocapnia.
- To aid in differentiating co-existing acid-base disorders.
Main Methods:
- Analysis of acid-base values in 13 patients with stable, controlled ventilation and respiratory paralysis.
- Measurement of arterial blood gases and related parameters across a range of carbon dioxide tensions (24-40 mmHg).
Main Results:
- A linear decrease in arterial blood hydrogen ion concentration was observed with decreasing carbon dioxide tension (0.32 nmol/L per mmHg).
- The slope of this response in chronic hypocapnia closely mirrors that found in chronic hypercapnia.
- Defined physiological response bands: ~10 nmol/L for hydrogen ions and 6 mmol/L for bicarbonate.
Conclusions:
- The study quantifies the human physiological response to chronic hypocapnia.
- Established significance bands provide a tool for diagnosing additional acid-base disturbances in this patient group.
- Findings contribute to improved clinical management of respiratory and metabolic disorders.
Related Concept Videos
01:31Chemical Factors Affecting Respiration Centers
Chemical factors such as changing CO2, O2, and H+ levels in arterial blood play a critical role in influencing respiration depth and rates. These variations are detected by chemoreceptors—specialized sensors located in two primary body areas. Central chemoreceptors are found throughout the brain stem, including the ventrolateral medulla, while peripheral chemoreceptors are located in the aortic arch and carotid arteries.
CO2 has a potent influence on respiration and is strictly regulated. Under...
CO2 has a potent influence on respiration and is strictly regulated. Under...
01:22Bicarbonate-Carbonic Acid Buffer
The carbonic acid-bicarbonate buffer system is critical for maintaining the body's pH balance. It operates on the equilibrium:
01:18Respiratory Regulation of Acid-Base Balance
Respiratory compensation is a vital physiological process that stabilizes blood plasma pH by regulating the partial pressure of carbon dioxide (PCO2), a key determinant of pH levels. Most carbon dioxide in the blood dissolves and converts into carbonic acid (H2CO3). It dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3⁻). There is also an inverse relationship between PCO2 and pH.
When carbon dioxide levels increase in the blood, more H+ and HCO3⁻ are produced, leading to a...
When carbon dioxide levels increase in the blood, more H+ and HCO3⁻ are produced, leading to a...
01:29Disorders of Acid-Base Balance
The human body maintains a precise pH range of arterial blood between 7.35 and 7.45. Deviations result in either acidosis (pH < 7.35) or alkalosis (pH > 7.45). These conditions are further classified as respiratory or metabolic disorders based on their underlying cause.
Respiratory Acidosis and Alkalosis
Respiratory acidosis occurs due to an increase in the partial pressure of carbon dioxide PCO2 in the blood. It often arises from shallow breathing or impaired gas exchange caused by...
Respiratory Acidosis and Alkalosis
Respiratory acidosis occurs due to an increase in the partial pressure of carbon dioxide PCO2 in the blood. It often arises from shallow breathing or impaired gas exchange caused by...
01:28Compensation Mechanisms
The human body employs intricate mechanisms to counteract changes in blood pH, preventing conditions like acidosis (pH < 7.35) and alkalosis (pH > 7.45). These compensatory responses aim to restore normal arterial blood pH by engaging respiratory or renal systems, depending on the source of the imbalance.
Respiratory Compensation
This mechanism addresses metabolic-induced pH imbalances by adjusting breathing rates. Respiratory compensation begins within minutes of detecting a pH...
Respiratory Compensation
This mechanism addresses metabolic-induced pH imbalances by adjusting breathing rates. Respiratory compensation begins within minutes of detecting a pH...
01:24Diagnosing Acidosis and Alkalosis
Diagnosing acid-base imbalances involves systematically analyzing arterial blood samples, focusing on three key measurements: pH, bicarbonate (HCO3−) concentration, and carbon dioxide partial pressure (PCO2). This analysis follows a four-step process that helps identify the imbalance's underlying cause and nature.
First, the pH level is assessed to determine whether the blood pH is normal (7.35–7.45), low (acidosis), or high (alkalosis).
Next, the PCO2 and HCO3− values are examined to...
First, the pH level is assessed to determine whether the blood pH is normal (7.35–7.45), low (acidosis), or high (alkalosis).
Next, the PCO2 and HCO3− values are examined to...