Respiratory alkalosis is a medical condition in which increased respiration (
hyperventilationIn medicine, hyperventilation is the state of breathing faster and/or deeper than necessary, bringing about lightheadedness and other undesirable symptoms often associated with panic attacks...
) elevates the blood
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
(a condition generally called
alkalosisAlkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma . Generally alkalosis is said to occur when pH of the blood exceeds 7.45...
). It is one of four basic categories of disruption of
acid-base homeostasisAcid-base homeostasis is the part of human homeostasis concerning the proper balance between acids and bases, in other words, the pH. The body is very sensitive to its pH level, so strong mechanisms to maintain it around 7.4 exist...
.
There are two types of respiratory alkalosis:
chronicIn medicine, a chronic disease is a disease that is long-lasting or recurrent. The term chronic describes the course of the disease, or its rate of onset and development. A chronic course is distinguished from a recurrent course; recurrent diseases relapse repeatedly, with periods of remission in...
and
acuteIn medicine, an acute disease is a disease with either or both of:# a rapid onset, as in acute infection# a short course ....
.
- Acute respiratory alkalosis occurs rapidly. During acute respiratory alkalosis, the person may lose consciousness where the rate of ventilation will resume to normal.
- Chronic respiratory alkalosis is a more long-standing condition.
Respiratory alkalosis is a medical condition in which increased respiration (
hyperventilationIn medicine, hyperventilation is the state of breathing faster and/or deeper than necessary, bringing about lightheadedness and other undesirable symptoms often associated with panic attacks...
) elevates the blood
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
(a condition generally called
alkalosisAlkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma . Generally alkalosis is said to occur when pH of the blood exceeds 7.45...
). It is one of four basic categories of disruption of
acid-base homeostasisAcid-base homeostasis is the part of human homeostasis concerning the proper balance between acids and bases, in other words, the pH. The body is very sensitive to its pH level, so strong mechanisms to maintain it around 7.4 exist...
.
Types
There are two types of respiratory alkalosis:
chronicIn medicine, a chronic disease is a disease that is long-lasting or recurrent. The term chronic describes the course of the disease, or its rate of onset and development. A chronic course is distinguished from a recurrent course; recurrent diseases relapse repeatedly, with periods of remission in...
and
acuteIn medicine, an acute disease is a disease with either or both of:# a rapid onset, as in acute infection# a short course ....
.
- Acute respiratory alkalosis occurs rapidly. During acute respiratory alkalosis, the person may lose consciousness where the rate of ventilation will resume to normal.
- Chronic respiratory alkalosis is a more long-standing condition. 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.
Mechanism
Respiratory alkalosis generally occurs when some stimulus (see "Causes" below) makes a person hyperventilate. The increased breathing produces increased alveolar respiration, expelling
CO2Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
from the circulation. This alters the dynamic
chemical equilibriumIn a chemical process, chemical equilibrium is the state in which the chemical activities or concentrations of the reactants and products have no net change over time. Usually, this would be the state that results when the forward chemical process proceeds at the same rate as their reverse reaction...
of carbon dioxide in the circulatory system, and the system reacts according to
Le Chatelier's principleIn chemistry, Le Chȃtelier's Principle, also called the Le Chȃtelier-Braun principle, can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Chȃtelier and Karl Ferdinand Braun who discovered it independently...
. Circulating hydrogen ions and bicarbonate are shifted through the
carbonic acidCarbonic acid has the formula H2CO3. It is also a name sometimes given to solutions of carbon dioxide in water, which contain small amounts of H2CO3. The salts of carbonic acids are called bicarbonates and carbonates. It is a weak acid...
(H
2CO
3) intermediate to make more CO
2 via the enzyme
carbonic anhydraseThe carbonic anhydrases form a family of enzymes that catalyze the rapid conversion of carbon dioxide to bicarbonate and protons, a reaction that occurs rather slowly in the absence of a catalyst...
according to the following reaction:
The net result of this is decreased circulating hydrogen ion concentration, and thus increased
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
(alkalosis). There is also a decrease in ionized blood
calciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the Earth's crust...
concentration.
Causes
Respiratory alkalosis may be produced accidentally by doctors (iatrogenically) during excessive
mechanical ventilationIn medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing.This may involve a machine called a ventilator or the breathing may be assisted by a physician or other suitable person compressing a bag or set of bellows...
. Other causes include:
- psychiatric
Psychiatry is a medical specialty officially devoted to the treatment and study of mental disorders. The term was first coined by the German physician Johann Christian Reil in 1808....
causes: anxietyAnxiety is a psychological and physiological state characterized by cognitive, somatic, emotional, and behavioral components. These components combine to create an unpleasant feeling that is typically associated with uneasiness, fear, or worry....
, hysteriaHysteria, in its colloquial use, describes a state of mind, one of unmanageable fear or emotional excesses. The fear is often caused by multiple events in one's past that involved some sort of severe conflict; the fear can be centered on a body part or most commonly on an imagined problem with that...
and stressStress is a biological term for the consequences of the failure of a human or animal to respond appropriately to emotional or physical threats to the organism, whether actual or imagined....
- CNS
CNS may refer to:In science:* Cell, Nature, and Science, acronym used to describe the three most prestigious scientific journals involved in biomedical research* Central nervous system, brain and spinal cord* Clinical nurse specialist...
causes: strokeA stroke is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by thrombosis or embolism or due to a hemorrhage...
, subarachnoid haemorrhageA subarachnoid hemorrhage is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain...
, meningitisMeningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
- drug use: doxapram
Doxapram hydrochloride is a respiratory stimulant. Administered intravenously, doxapram stimulates an increase in tidal volume, and respiratory rate.-Mode of action:...
, aspirinAspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication....
, caffeineCaffeine is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term kaffein, a chemical compound in coffee, which in English became caffeine...
and coffeeCoffee is a brewed beverage prepared from roasted seeds, commonly called coffee beans, of the coffee plant. They are seeds of "coffee cherries" that grow on trees in over 70 countries. It has been said that green coffee is the second most traded commodity in the world behind crude oil. Due to its...
abuse
- moving into high altitude
High altitude are regions on the Earth's surface that are high above mean sea level. The pressure and temperature of the atmosphere at high altitude is substantially different than at sea level. These differences can affect living organisms, including humans...
areas, where the low atmospheric pressureAtmospheric pressure is defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above...
of oxygen stimulates increased ventilation
- lung disease such as pneumonia
Pneumonia is an inflammatory illness of the lung. Frequently, it is described as lung parenchyma/alveolar inflammation and abnormal alveolar filling with fluid ....
, where a hypoxic driveThe hypoxic drive is a form of respiratory drive in which the body uses oxygen chemoreceptors instead of carbon dioxide receptors to regulate the respiratory cycle....
governs breathing more than CO2 levels (the normal determinant)
- fever
Fever is a frequent medical sign that describes an increase in internal body temperature to levels above normal...
, which stimulates the respiratory centre in the brainstem
- pregnancy
Pregnancy is the carrying of one or more offspring, known as a fetus or embryo, inside the uterus of a female. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets. Human pregnancy is the most studied of all mammalian pregnancies. Obstetrics is the surgical field...
- sexual activity, which may induce excessive breathing due to excitation
Symptoms
Symptoms of respiratory alkalosis are related to the decreased blood carbon dioxide levels, and include peripheral paraesthesiae. In addition, the alkalosis may disrupt calcium ion balance, and cause the symptoms of
hypocalcaemiaIn medicine, hypocalcemia is the presence of low serum calcium levels in the blood, usually taken as less than 2.1 mmol/L or 9 mg/dl or an ionized calcium level mm of less than 1.1 mmol/L . It is a type of electrolyte disturbance...
(such as
tetanyTetany is a medical sign, the involuntary contraction of muscles, caused by diseases and other conditions that increase the action potential frequency...
and fainting) with no fall in total serum calcium levels.
See also
- Metabolic alkalosis
Metabolic alkalosis is a metabolic condition in which the pH of the blood is elevated beyond the normal range . This is usually the result of decreased hydrogen ion concentration, leading to increased bicarbonate, or alternatively a direct result of increased bicarbonate...
- Respiratory acidosis
Respiratory acidosis is a medical condition in which decreased respiration causes increased blood carbon dioxide and decreased pH ....
- Hypocalcemia