• Definition
    • Hyperventilation is Defined as an Increase in Respiratory Rate and/or Tidal Volume, Resulting in the Elimination of More Carbon Dioxide than the Body Produces
      • Hyperventilation Results in Hypocapnia (Decreased Arterial pCO2) and Respiratory Alkalosis (at Least Initially, Until Renal Compensation Results in Bicarbonate Excretion with an Eventual Decrease in the pH Back Toward Normal) (see Respiratory Alkalosis)

Hyperpnea (see Hyperpnea)

  • Definition
    • Hyperpnea is Defined as an Increase in Tidal Volume with or without an Increase in Respiratory Rate

Tachypnea (see Tachypnea)

  • Definition
    • Tachypnea is Defined as an Increase in Respiratory Rate

Hypocapnia (see Hypocapnia)

  • Definition
    • Hypocapnia is Defined as Decrease in the Arterial pCO2 (i.e. Low Partial Pressure of Arterial Blood Carbon Dioxide)


  • Definition
    • Alkalemia is Defined as Increase in the Arterial pH >7.40 (at Least Initially)
  • Note that a Patient Can Be Alkalemic without Having a Respiratory Alkalosis
    • Example
      • Metabolic Alkalosis Can Produce Alkalemia without the Presence of a Respiratory Alkalosis

Respiratory Alkalosis (see Respiratory Alkalosis)

  • Definition
    • Respiratory Alkalosis is Defined as an Acid-Base Disorder Characterized by a Decrease in Arterial pCO2 with an Associated Increase in Arterial pH (at Least Initially)
  • Note that a Patient Can Have a Respiratory Alkalosis without Being Alkalemic
    • Example
      • Due to Normal Compensatory Mechanisms, Chronic Respiratory Alkalosis Induces Metabolic (Predominantly Renal) Compensation (with a Progressive Decrease in Serum Bicarbonate Over Time), Culminating in Only Minimal/Absent Alkalemia

Etiology of Hyperventilation/Hypocapnia/Respiratory Alkalosis (see Hypocapnia and Respiratory Alkalosis)

Cardiovascular Disease-Induced Hyperventilation

Congestive Heart Failure (CHF) (see Congestive Heart Failure)

Hypotension (see Hypotension)

Fever/Sepsis-Induced Hyperventilation (see Fever and Sepsis)



Hypoxemia-Induced Hyperventilation

High Altitude (see Chronic Mountain Sickness)

Intracardiac Shunt (see Intracardiac and Extracardiac Shunt)

Pulmonary Disease (of Any Etiology Resulting in Hypoxemia)

Metabolic Disorder-Induced Hyperventilation

Acidosis (i.e. Acidemia of Any Etiology) (see Metabolic Acidosis-Elevated Anion Gap and Metabolic Acidosis-Normal Anion Gap)

Hyperthyroidism (see Hyperthyroidism)

Liver Disease

Severe Anemia (see Anemia)

Neurologic/Psychogenic Disorder-Induced Hyperventilation

Anxiety/Panic Disorder (see Anxiety)

Brainstem Tumor

Central Nervous System Infection

Intracerebral Hemorrhage (see Intracerebral Hemorrhage)

Ischemic Cerebrovascular Accident (CVA) (see Ischemic Cerebrovascular Accident)

Psychogenic Hyperventilation

Traumatic Brain Injury (TBI) (see Traumatic Brain Injury)


Pain-Induced Hyperventilation


Pregnancy (and Luteal Phase of Menstrual Cycle)-Induced Hyperventilation (see Pregnancy)


Pulmonary Disease-Induced Hyperventilation

Asthma (see Asthma)

Cardiogenic Pulmonary Edema (see Cardiogenic Pulmonary Edema)

Chest Wall Disease

Community-Acquired Pneumonia (CAP)/Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia (VAP) (see Community-Acquired Pneumonia and Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia)

Interstitial Lung Disease (ILD) (see Interstitial Lung Disease)

Pneumothorax (see Pneumothorax)

Pulmonary Vascular Disease

Drug-Induced Hyperventilation

Beta-2 Adrenergic Receptor Agonists (see β2-Adrenergic Receptor Agonists)

Doxapram (Dopram, Stimulex Respiram) (see Doxapram)


Progesterone (see Progesterone)

Salicylate Intoxication (see Salicylates)


Normal Acid-Base Physiology

Renal Compensatory Response to Respiratory Alkalosis


Arterial Blood Gas (ABG) (see Arterial Blood Gas)

Clinical Manifestations of of Hyperventilation/Hypocapnia/Respiratory Alkalosis (see Hyperventilation and Respiratory Alkalosis)

General Comments

Cardiovascular Manifestations


Chest Pain (see xxxx)

Myocardial Ischemia (see Coronary Artery Disease)

Palpitations (see Palpitations)

Syncope (see Syncope)

Dermatologic Manifestations

Diaphoresis (see Diaphoresis)

Neurologic Manifestations

Carpopedal Spasm (see Carpopedal Spasm)

Dizziness/lightheadedness (see Dizziness)

Muscle Cramps (see Muscle Cramps)

Neonatal Brain Injury

Paresthesias (see Paresthesias)

Poorer Outcome in Traumatic Brain Injury (TBI) (see Traumatic Brain Injury)

Poorer Outcome in Acute Ischemic Cerebrovascular Accident (CVA) (see Ischemic Cerebrovascular Accident)

Postoperative Psychomotor Dysfunction

Seizures (see Seizures)

Tetany (see Tetany)

Pulmonary Manifestations

Bronchospasm (see Bronchospasm)

Acute Respiratory Distress Syndrome (ARDS) (see Acute Respiratory Distress Syndrome)