Respiratory alkalosis

<figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline>

Resident Survival Guide

Respiratory alkalosis
ICD-10	E87.3
ICD-9	276.3
DiseasesDB	406

WikiDoc Resources for Respiratory alkalosis
Articles
Most recent articles on Respiratory alkalosis Most cited articles on Respiratory alkalosis Review articles on Respiratory alkalosis Articles on Respiratory alkalosis in N Eng J Med, Lancet, BMJ
Media
Powerpoint slides on Respiratory alkalosis Images of Respiratory alkalosis Photos of Respiratory alkalosis Podcasts & MP3s on Respiratory alkalosis Videos on Respiratory alkalosis
Evidence Based Medicine
Cochrane Collaboration on Respiratory alkalosis Bandolier on Respiratory alkalosis TRIP on Respiratory alkalosis
Clinical Trials
Ongoing Trials on Respiratory alkalosis at Clinical Trials.gov Trial results on Respiratory alkalosis Clinical Trials on Respiratory alkalosis at Google
Guidelines / Policies / Govt
US National Guidelines Clearinghouse on Respiratory alkalosis NICE Guidance on Respiratory alkalosis NHS PRODIGY Guidance FDA on Respiratory alkalosis CDC on Respiratory alkalosis
Books
Books on Respiratory alkalosis
News
Respiratory alkalosis in the news Be alerted to news on Respiratory alkalosis News trends on Respiratory alkalosis
Commentary
Blogs on Respiratory alkalosis
Definitions
Definitions of Respiratory alkalosis
Patient Resources / Community
Patient resources on Respiratory alkalosis Discussion groups on Respiratory alkalosis Patient Handouts on Respiratory alkalosis Directions to Hospitals Treating Respiratory alkalosis Risk calculators and risk factors for Respiratory alkalosis
Healthcare Provider Resources
Symptoms of Respiratory alkalosis Causes & Risk Factors for Respiratory alkalosis Diagnostic studies for Respiratory alkalosis Treatment of Respiratory alkalosis
Continuing Medical Education (CME)
CME Programs on Respiratory alkalosis
International
Respiratory alkalosis en Espanol Respiratory alkalosis en Francais
Business
Respiratory alkalosis in the Marketplace Patents on Respiratory alkalosis
Experimental / Informatics
List of terms related to Respiratory alkalosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Priyamvada Singh, M.D. [2]Madhu Sigdel M.B.B.S.[3]

Overview

Respiratory alkalosis is an acid-base disorder, primarily a decrease in partial pressure of carbon dioxide in arterial blood i.e.PaCo2 [normal PaCo2 is 40 mm Hg on average with range between 35-45mm Hg] with or without compensatory decrease in serum bicarbonate [HCO3-] and pH being alkaline (normal pH of blood is 7.35-7.45). Respiratory alkalosis in almost all cases results from increased alveolar respiration (hyperventilation) leading to decrease in blood carbon dioxide concentration measured as PaCO2. This leads to decreased hydrogen ion [H+] and bicarbonate [HCO3-] concentrations. Decreased [H+] leads to increase in pH leading to alkalosis.

Pathophysiology

production of CO2 in body tissues(from oxidation of fat, carbohydrate and carbon skeleton of amino acids in normal metabolic process produces carbon dioxide and water) and elimination of CO2 through lungs are in equilibrium under normal physiology. Most of tissue CO2 is brought to lungs as plasma venous bicarbonate ions.

Compensation in respiratory alkalosis

compensation for respiratory alkalosis is mediated through kidneys.

Acute compensatory stage

• Starts within minutes to hours
• Mediated through the plasma buffer
• For every PaCO2 decrease of 10 mm Hg, serum bicarbonate decreases by 1-2mEq/L
• Change in pH is unpredictable

Chronic compensatory stage

• Renal mediated
• Starts after 24-36 hours and renal compensation for sustained hypocapnia is complete in 36-72 hours
• For every PaCO2 decrease of 10 mm Hg, serum bicarbonate decreases by 5mEq/L
• Change in pH is unpredictable

Classification

There are two types of respiratory alkalosis: chronic and acute.

Acute respiratory alkalosis

• Lasting for less than 24-48 hours
• Increased levels of carbon dioxide are "blown off" by the lungs, which are hyperventilating.
• During acute respiratory alkalosis, the person may lose consciousness where the rate of ventilation will resume to normal.

Chronic respiratory alkalosis

• Lasting for longer than 24-48 hours
• For every 10 mM drop in pCO₂ in blood, there is a corresponding 5 mM of bicarbonate ion drop.
• The drop of 5 mM of bicarbonate ion is a compensation effect which reduces the alkalosis effect of the drop in pCO₂ in blood. This is termed metabolic compensation.

Causes

Lung and airways

• Pneumonia
• Pulmonary embolus
• Bronchospasm
• Restrictive lung disease

Central respiratory drive

• Pain
• Anxiety
• Fever
• High altitude
• CNS tumor
• Drugs like doxapram and large doses of aspirin (stimulate the respiratory center), Gallium nitrate
• CNS causes, including stroke, subarachnoid haemorrhage, meningitis, encephalitis
• Caffeine overdose and coffee abuse, methylxanthines (eg. theophyllin, aminophyllin)
• Progesterone

Systemic diseases

• Sepsis
• Salicylates
• Liver failure
• Hyperthyroid
• Pregnancy
• Hypotension
• CHF
• Anxiety, hysteria, and stress
• Iatrogenically during mechanical ventilation of patients

Special considerations

• Sepsis or salicylate toxicity are the only single disorders that cause both an elevated anion gap metabolic acidosis and a respiratory alkalosis.
• Ischemia, infection or infarction of the central respiratory centers may result either respiratory acidosis (decreased respiratory drive) or respiratory alkalosis (increased respiratory drive)
• Asthma, and Pneumonia can also present with either repiratory alkalosis or acidosis. Asthma typically presents with a respiratory alkalosis, however as the patient tires, respiratory acidosis may occur.
• Pulmonary embolus can be a life threatening condition and often presents as respiratory alkalosis.
• Progesterone is sometimes used as a respiratory stimulant in obstructive sleep apnea and hypoventilation.

Symptoms

• Symptoms of acute respiratory alkalosis are related to the decrease blood carbon dioxide levels (PaCO2) that leads to reduced cerebral blood flow resulting from vasoconstriction of cerebral vessels. Most of the symptoms arise when PaCO2 falls below 30 mm Hg and include:
  • Light-headedness, syncope
  • Confusion,
  • Seizures,
  • Peripheral and circumoral paresthesias, and cramps.
  • Chest pain and shortness of breath are seen in patients hyperventilating due to pain or anxiety.
  • Chronic respiratory alkalosis is generally well tolerated without apparent clinical symptoms
• Signs include:
  • Tachypnea or hyperpnea,
  • Carpopedal spasm due to tetany as a result of decreased levels of ionized calcium in the blood (ionized calcium are driven inside cells in exchange for hydrogen ion [H+] as compensatory mechanism to correct pH) with no fall in total serum calcium level. Alkalosis also increases protein-bound fraction of calcium reducing free calcium.
  • Respiratory patterns in respiratory alkalosis my be regular with increased rate and tidal volume OR Cheyne-Stokes type

Related Chapters

• Metabolic alkalosis
• Acid-base imbalance
• Metabolic acidosis
• Respiratory acidosis
• Anion gap
• Hypocalcemia