Respiratory alkalosis resident survival guide

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Respiratory alkalosis Resident Survival Guide Microchapters

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rinky Agnes Botleroo, M.B.B.S.
Synonyms and keywords: Approach to respiratory alkalosis, Respiratory alkalosis management, Respiratory alkalosis Workup


The normal physiological pH of blood is 7.35 to 7.45. An increase above this range is known as alkalosis. Respiratory alkalosis is a state where the body’s pH is more than 7.45 secondary to some respiratory or pulmonary cause.Respiratory alkalosis is characterized by the presence of low pCO2and high pH (>7.40). Respiratory alkalosis occurs when a person breathes too quickly or too deep and carbon dioxide levels drop too low. This causes the pH of the blood to increase and become too alkaline. It is also known as the primary hypocapnia in which patients usually present with hyperventilation. The resultant alkalinization of body fluids is balanced by a decrease in serum [HCO3-]. Secondary hypocapnia should be differentiated from primary hypocapnia, as the former occurs in response to metabolic acidosis. When respiratory alkalosis develops, a decrease in serum [HCO3-] occurs within a few minutes. This is due to non-bicarbonate buffering as well as H+ release from tissues. This buffering from various sources persists for several hours, and the resultant acid-base disturbance is called acute respiratory alkalosis. During acute respiratory alkalosis, the H+ secretion in both proximal tubule and cortical collecting duct is suppressed. When alkalemia persists, renal compensation starts with a decrease in both H+ secretion and basolateral exit of [HCO3-]in the proximal tubule. This lowers more serum [HCO3-], due to which the pH is maintained close to normal. The complete renal compensation takes 2–3 days to occur, and when a new steady state is established, it is called chronic respiratory alkalosis.


Life-Threatening Causes

Life-threatening causes of Respiratory Alkalosis include:

Common Causes


Shown below is an algorithm summarizing the diagnosis of Respiratory Alkalosis:[3][4]

Patient with Acute Respiratory Alkalosis
Take complete history
Ask the following questions regarding CNS manifestations

❑ If they felt dizzy or confused recently? Light-headedness and confusion due to reduced cerebral blood flow

❑ If they felt numbness or tingling sensation on peripheral parts of the body?

Acral paresthesia due to reduced blood flow to the skin

❑ Ask if they had experienced tremor of the hand when the wrist is extended, sometimes said to resemble a bird flapping its wings to check asterexis

❑ If there is any history of loss of consciousness

❑ Ask about any event of seizures
Ask the following questions regarding Cardiovascular manifestations

❑ Ask if they felt any chest discomfort or pain?

Chest pain due to vasoconstriction

❑ If they felt their heart was racing? Ask about cardiac arrythmia
Ask the following questions regarding metabolic effects

❑ Ask if they have experienced perioral tingling sensations


❑Ask about any symptoms of mild hyponatremia, hypokalemia, and hypophosphatemia
Do complete physical examination
Vital signs

❑ Decreased blood pressure(hypotension) due to hypoxemia

❑ Increased heart rate due to fever, anxiety

❑ Increased temperature due to infection or sepsis

Tachypnea due to Arrhythmias, hypoxemia, pulmonary disease

❑ Orthostatic changes due to reduced plasma volume

Examination of respiratory system

❑ Inspiratory crackles if patient has pulmonary edema

❑ Inspiratory ronchi and crackles in patient with pulmonary fibrosis

Tachypnea, pulmonary rub in Pulmonary embolism

❑ Prolonged expiratory wheezing in patient with Asthma

Examination of Cardiovascular System

❑ Irregular rhythm may be seen

❑ Palpable P2, right ventricular heave may be seen if patient has pulmonary hypertension
Examination of Abdomen

Ascites in liver disease

Gravid uterus in pregnant women
Examination of the Extremities

Cyanosis due to hypoxemia

Examination of Central Nervous System

Tremor, paresthesias

❑ Muscle weakness Hypokalemia, hypophosphatemia

Chvostek’s and Trousseau’s signs due to low ionized Ca2+
Do following tests
Serum Chemistry

❑ Persistent hyponatremia, hypokalemia, hypophosphatemia, and low ionized


❑Increased WBC if there is any infection

❑ Decreased hemoglobin if there is anemia

❑ Increased Hematocrit which is suggestive of exposure to high altitude

❑ Abnormal liver function tests in liver disease

❑ Increased T3 and T4 and low TSH in a patient of hyperthyroidism

❑ Positive urine β-human chorionic hormone if patient is pregnant

❑ When both respiratory alkalosis and high Anion gap metabolic acidosis are present—suspect salicylate intake
Do Arterial Blood Gas (ABG)

❑ Low pCO2, low serum [HCO3−], high pH

❑ In acute respiratory alkalosis, serum [HCO3−] is around 20 mEq/L,
because the secondary response to hypocapnia of 20 mmHg is a decrease of 4 mEq/L from normal [HCO3−] of 24 mEq/L

❑ Serum [HCO3−] from normal level of 24 mEq/L drops to

16 mEq/L in chronic respiratory alkalosis for the same hypocapnia of 20 mmHg.



  • Respiratory alkalosis is not self-limiting.
  • Correction of the primary disorder of the respiratory alkalosis is needed
  • Shown below is an algorithm summarizing the treatment of Respiratory Alkalosis:
If patient comes with Anxiety or hyperventilation syndromes
Treatment options

❑ Breathing into a paper or plastic bag
❑ Mild sedation
❑ Reassurance
❑ To view treatment of panic attack click here
If patient is Hypoxic
Treatment options

❑ Give O2
Respiratory Alkalosis
Salicylates overdose
Treatment options

❑ Urinary alkalinization
❑ Forced diuresis
If patient has Hyperthyroidism
Treatment options

Antithyroid medications
❑ To view treatment of hyperthyroidism click here
If patient has Asthma
Treatment options

❑ To view treatment of asthma click here
If patient has Pneumonia
Treatment options

❑ To view treatment of pneumonia click here
If patient has pulmonary oedema
Treatment options

❑ Treatment and improvement in CHF
❑ To view treatment of pulmonary edema click here
If patient has pulmonary embolism
Treatment options

❑ Give O2
❑ To view treatment of pulmonary embolism click here
If patient has history of going to high altitude climbing
Treatment options

❑ Give O2
❑ To view treatment of altitude sickness click here
Mechanical ventilation
Treatment options

❑ Reduce ventilatory rate and tidal volume
❑ Increase dead space
❑ Mild sedation without skeletal muscle paralysis


  • Patient may experience faster and deeper breathing, physician should provide reassurance and empathy which can help to get patient's breathing under control.[5]
  • Physicians should look for the underlying cause and its severity.
  • A patient who suffers from regular respiratory alkalosis can seek help from a therapist and can learn breathing exercises, meditation, and regular exercise.[5]


  • Patients should not hesitate to seek help from professionals in case of recurrence of respiratory alkalosis.


  1. "Respiratory Alkalosis - StatPearls - NCBI Bookshelf".
  2. Hopkins E, Sanvictores T, Sharma S. PMID 29939584. Missing or empty |title= (help)
  3. Hasan, Ashfaq (2009). "Respiratory Alkalosis": 207–212. doi:10.1007/978-1-84800-334-7_9.
  4. Reddi, Alluru S. (2018). "Respiratory Alkalosis": 441–448. doi:10.1007/978-3-319-60167-0_33.
  5. 5.0 5.1 "Respiratory Alkalosis: Symptoms, Treatments, and Prevention".