Oxygen therapy, also known as supplemental oxygen, is the use of

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

as medical treatment. Acute indications for therapy include

hypoxemia Hypoxemia is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia has many causes, and often causes hypoxia as the blood is not supplying enough oxygen to the tissues of the bod ...

(low blood oxygen levels), carbon monoxide toxicity and

cluster headache Cluster headache (CH) is a neurological disorder characterized by recurrent severe headaches on one side of the head, typically around the eye(s). There is often accompanying eye watering, nasal congestion, or swelling around the eye on the af ...

. It may also be prophylactically given to maintain blood oxygen levels during the induction of anesthesia. Oxygen therapy is often useful in chronic hypoxemia caused by conditions such as severe

COPD Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce ...

or cystic fibrosis. Oxygen can be delivered via

nasal cannula The nasal cannula (NC) is a device used to deliver supplemental oxygen or increased airflow to a patient or person in need of respiratory help. This device consists of a lightweight tube which on one end splits into two prongs which are place ...

or face mask, or via high pressure conditions such as in

endotracheal intubation Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. It is frequently ...

hyperbaric chamber A diving chamber is a vessel for human occupation, which may have an entrance that can be sealed to hold an internal pressure significantly higher than ambient pressure, a pressurised gas system to control the internal pressure, and a supply of ...

. It can also be given through bypassing the airway, such as in

ECMO Extracorporeal membrane oxygenation (ECMO), also known as extracorporeal life support (ECLS), is an extracorporeal technique of providing prolonged cardiac and respiratory support to persons whose heart and lungs are unable to provide an adequat ...

therapy. Oxygen is required for normal

cellular metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...

. However, excessively high concentrations can result in

oxygen toxicity Oxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen () at increased partial pressures. Severe cases can result in cell damage and death, with effects most often seen in the central nervous system, lu ...

, leading to lung damage and

respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise ...

. Higher oxygen concentrations can also increase the risk of airway fires, particularly while smoking. Oxygen therapy can also dry out the nasal mucosa without humidification. In most conditions, an oxygen saturation of 94–96% is adequate, while in those at risk of

carbon dioxide retention Hypercapnia (from the Greek ''hyper'' = "above" or "too much" and ''kapnos'' = "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous pr ...

, saturations of 88–92% are preferred. In cases of carbon monoxide toxicity or

cardiac arrest Cardiac arrest is when the heart suddenly and unexpectedly stops beating. It is a medical emergency that, without immediate medical intervention, will result in sudden cardiac death within minutes. Cardiopulmonary resuscitation (CPR) and poss ...

, saturations should be as high as possible. While

air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...

is typically 21% oxygen by volume, oxygen therapy can increase O₂ content of air up to 100%. The medical use of oxygen first became common around 1917, and is the most common hospital treatment in the developed world. It is currently on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...

. Home oxygen can be provided either by

oxygen tanks An oxygen tank is an oxygen storage vessel, which is either held under pressure in gas cylinders, or as liquid oxygen in a cryogenic storage tank. Uses Oxygen tanks are used to store gas for: * medical breathing at medical facilities and at home ...

oxygen concentrator An oxygen concentrator is a device that concentrates the oxygen from a gas supply (typically ambient air) by selectively removing nitrogen to supply an oxygen-enriched product gas stream. They are used industrially and as medical devices for oxy ...

Medical uses

Oxygen is widely used by hospitals, EMS, and

first-aid First aid is the first and immediate assistance given to any person with either a minor or serious illness or injury, with care provided to preserve life, prevent the condition from worsening, or to promote recovery. It includes initial int ...

providers in a variety of conditions and settings. A few indications frequently requiring high-flow oxygen include resuscitation, major trauma,

anaphylaxis Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the foll ...

, major

bleeding Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...

shock Shock may refer to: Common uses Collective noun *Shock, a historic commercial term for a group of 60, see English numerals#Special names * Stook, or shock of grain, stacked sheaves Healthcare * Shock (circulatory), circulatory medical emergen ...

, active

convulsions A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is sometimes used as a s ...

, and

hypothermia Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...

Acute conditions

In context of acute hypoxemia, oxygen therapy should be titrated to a target level based on

pulse oximetry Pulse oximetry is a noninvasive method for monitoring a person's oxygen saturation. Peripheral oxygen saturation (SpO2) readings are typically within 2% accuracy (within 4% accuracy in 95% of cases) of the more accurate (and invasive) reading o ...

(94–96% in most patients, or 88–92% in people with COPD). This can be performed by increasing oxygen delivery, described as F_{I_O₂}(fraction of inspired oxygen). In 2018, the British Medical Journal recommended that oxygen therapy be stopped for saturations greater than 96% and not started for saturations above 90 to 93%. This may be due to an association between excessive oxygenation in the acutely ill and increased mortality. Exceptions to these recommendations include

carbon monoxide poisoning Carbon monoxide poisoning typically occurs from breathing in carbon monoxide (CO) at excessive levels. Symptoms are often described as " flu-like" and commonly include headache, dizziness, weakness, vomiting, chest pain, and confusion. Large ...

s, sickle cell crisis, and

pneumothorax A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath. In a minority of cases, a one-way valve i ...

. Oxygen therapy has also been used as emergency treatment for

decompression sickness Decompression sickness (abbreviated DCS; also called divers' disease, the bends, aerobullosis, and caisson disease) is a medical condition caused by dissolved gases emerging from solution as bubbles inside the body tissues during decompressio ...

for years. Recompression in a

with 100% oxygen is the standard treatment for

decompression illness Decompression Illness (DCI) comprises two different conditions caused by rapid decompression of the body. These conditions present similar symptoms and require the same initial first aid. Scuba divers are trained to ascend slowly from depth to av ...

. The success of recompression therapy is greatest if given within four hours after resurfacing, with earlier treatment associated with a decreased number of recompression treatments required for resolution. It has been suggested in literature that

heliox Heliox is a breathing gas mixture of helium (He) and oxygen (O2). It is used as a medical treatment for patients with difficulty breathing because mixture generates less resistance than atmospheric air when passing through the airways of the lung ...

may be a better alternative to oxygen therapy. In the context of stroke, oxygen therapy may be beneficial as long as hyperoxic environments are avoided. People receiving outpatient oxygen therapy for hypoxemia following acute illness or hospitalization should be re-assessed by a physician prior to prescription renewal to gauge the necessity of ongoing oxygen therapy., which cites * * * If the initial hypoxemia has resolved, additional treatment may be an unnecessary use of resources.

Chronic conditions

Common conditions which may require a baseline of supplementary oxygen include

chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce ...

(COPD),

chronic bronchitis Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. ...

, and emphysema. Patients may also require additional oxygen during acute exacerbations. Oxygen may also be prescribed for

breathlessness Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing dis ...

, end-stage cardiac failure, respiratory failure, advanced cancer, or neurodegenerative disease in spite of relatively normal blood oxygen levels. Physiologically, it may be indicated in people with arterial oxygen partial pressure Pa ≤ 55mmHg (7.3kPa) or arterial oxygen saturation Sa ≤ 88%. Careful titration of oxygen therapy should be considered in patients with chronic conditions predisposing them to carbon dioxide retention (e.g., COPD, emphysema). In these instances, oxygen therapy may decrease respiratory drive, leading to accumulation of carbon dioxide (hypercapnia),

acidemia Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma. The term ''acidemia'' describes t ...

, and increased mortality secondary to respiratory failure. Improved outcomes have been observed with titrated oxygen treatment largely due to gradual improvement of the

ventilation/perfusion ratio In respiratory physiology, the ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the matching of two variables: * V – ventilation – the air that reaches the alveoli * Q – perfusion – the blo ...

. The risks associated with loss of respiratory drive are far outweighed by the risks of withholding emergency oxygen, so emergency administration of oxygen is never contraindicated. Transfer from the field to definitive care with titrated oxygen typically occurs long before significant reductions to the respiratory drive are observed.

Contraindications

There are certain situations in which oxygen therapy has been shown to negatively impact a person's condition. * Oxygen therapy can exacerbate the effects of paraquat poisoning and should be withheld unless severe respiratory distress or respiratory arrest is present. Paraquat poisoning is rare, with about 200 deaths globally from 1958 to 1978. * Oxygen therapy is not recommended for people with

pulmonary fibrosis Pulmonary fibrosis is a condition in which the lungs become scarred over time. Symptoms include shortness of breath, a dry cough, feeling tired, weight loss, and nail clubbing. Complications may include pulmonary hypertension, respiratory failu ...

bleomycin -13- (1''H''-imidazol-5-yl)methyl9-hydroxy-5- 1''R'')-1-hydroxyethyl8,10-dimethyl-4,7,12,15-tetraoxo-3,6,11,14-tetraazapentadec-1-yl}-2,4'-bi-1,3-thiazol-4-yl)carbonyl]amino}propyl)(dimethyl)sulfonium , chemical_formula = , C=55 , H=84 , N=1 ...

-associated lung damage. * Acute respiratory distress syndrome, ARDS caused by acid aspiration may be exacerbated with oxygen therapy according to some animal studies. * Hyperoxic environments should be avoided in cases of sepsis. o2regulator

Adverse effects

In some instances, oxygen delivery can lead to particular complications in population subsets. * In infants with respiratory failure, administration of high levels of oxygen can sometimes promote overgrowth of new blood vessels in the eye leading to blindness. This phenomenon is known as

retinopathy of prematurity Retinopathy of prematurity (ROP), also called retrolental fibroplasia (RLF) and Terry syndrome, is a disease of the eye affecting prematurely born babies generally having received neonatal intensive care, in which oxygen therapy is used due to ...

(ROP). * In rare instances, people receiving hyperbaric oxygen therapy have had seizures, which has been previously attributed to

. * There is some evidence that extended HBOT can accelerate development of

cataracts A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble w ...

Alternative medicine

Some practitioners of alternative medicine have promoted "oxygen therapy" as a cure for many human ailments including AIDS, Alzheimer's disease and

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

. According to the American Cancer Society, "available scientific evidence does not support claims that putting oxygen-releasing chemicals into a person's body is effective in treating cancer", and some of these treatments can be dangerous.

Physiologic Effects

Oxygen supplementation has a variety of physiologic effects on the human body. Whether or not these effects are adverse to a patient is dependent upon clinical context. Cases in which an excess amount of oxygen is available to organs is known as

hyperoxia Hyperoxia occurs when cells, tissues and organs are exposed to an excess supply of oxygen (O2) or higher than normal partial pressure of oxygen. In medicine, it refers to excessive oxygen in the lungs or other body tissues, which can be caused ...

. While the following effects may observed with noninvasive high-dose oxygen therapy (i.e., not

), delivery of oxygen at higher pressures is associated with exacerbation of the following associated effects.

Absorption atelectasis

It has been theorized that oxygen therapy may promote accelerated development of

atelectasis Atelectasis is the collapse or closure of a lung resulting in reduced or absent gas exchange. It is usually unilateral, affecting part or all of one lung. It is a condition where the alveoli are deflated down to little or no volume, as distinct ...

(partial or complete lung collapse), as well as denitrogenation of gas cavities (e.g.,

pneumocephalus Pneumocephalus is the presence of air or gas within the cranial cavity. It is usually associated with disruption of the skull: after head and facial trauma, tumors of the skull base, after neurosurgery or otorhinolaryngology, and rarely, spont ...

). This concept is based on the idea that oxygen is more quickly absorbed compared to nitrogen within the body, leading oxygen-rich areas that are poorly ventilated to be rapidly absorbed, leading to atelectasis. It is thought that higher fractions of inhaled oxygen (''F_I''O₂) is associated with increasing rates of atelectasis in the clinical scenario. In clinically healthy adults, it is believed that absorption atelectasis typically does not have any significant implications when managed properly.

Airway inflammation

In regard to the airway, both

tracheobronchitis Tracheobronchitis is inflammation of the trachea and bronchi. It is characterised by a cough, fever, and purulent (containing pus) sputum and is therefore suggestive of pneumonia. It is classified as a respiratory tract infection. Tracheobronchitis ...

and

mucositis Mucositis is the painful inflammation and ulceration of the mucous membranes lining the digestive tract, usually as an adverse effect of chemotherapy and radiotherapy treatment for cancer. Mucositis can occur anywhere along the gastrointestina ...

have been observed with high levels of oxygen delivery (typically >40% O2). Within the lungs, these elevated concentrations of oxygen have been associated with increased alveolar toxicity (coined the Lorrain-Smith effect). Mucosal damage is observed to increase with elevated atmospheric pressure and oxygen concentrations, which may result in the development of Acute respiratory distress syndrome, ARDS and possibly death.

Central nervous system effects

Decreased cerebral blood flow and

intracranial pressure Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury ( mmHg) and at rest, is normally 7–15 mmHg for a supine adult ...

(ICP) have been reported in hyperoxic conditions, with mixed results regarding impact on cognition. Hyperoxia as also been associated with

seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...

cataract A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble ...

formation, and reversible myopia.

Hypercapnea

Among retainers, excess exposure to oxygen in context of the Haldane effect causes decreased binding of deoxyhemoglobin to in the blood. This unloading of may contribute to the development of acid-base disorders due to the associated increase in PaCO2 ( hypercapnea). Patients with underlying lung disease such as COPD may not be able to adequately clear the additional produced by this effect, worsening their condition. In addition, oxygen therapy has also been shown to decrease respiratory drive, further contributing to possible hypercapnea.

Immunological effects

Hyperoxic environments have been observed to decrease granulocyte rolling and

diapedesis Leukocyte extravasation (also commonly known as leukocyte adhesion cascade or diapedesis – the passage of cells through the intact vessel wall) is the movement of leukocytes out of the circulatory system and towards the site of tissue damage o ...

in specific circumstances in humans. In regard to anaerobic infections, cases of

necrotizing fasciitis Necrotizing fasciitis (NF), also known as flesh-eating disease, is a bacterial infection that results in the death of parts of the body's soft tissue. It is a severe disease of sudden onset that spreads rapidly. Symptoms usually include red or p ...

have been observed to require fewer debridement operations and have improvement in regard to mortality in patients treated with hyperbaric oxygen therapy. This may stem from oxygen intolerance of otherwise anaerobic microorganisms.

Oxidative Stress

Sustained exposure to oxygen may overwhelm the body's capacity to deal with

oxidative stress Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal ...

. Rates of oxidative stress appears to be influenced by both oxygen concentration and length of exposure, with general toxicity observed to occur within hours in certain hyperoxic conditions.

Reduction in erythropoiesis

Hyperoxia is observed to result in a serum reduction in erythropoietin, resulting in reduced stimulus for

erythropoiesis Erythropoiesis (from Greek 'erythro' meaning "red" and 'poiesis' "to make") is the process which produces red blood cells (erythrocytes), which is the development from erythropoietic stem cell to mature red blood cell. It is stimulated by decrea ...

. Hyperoxia at normobaric environments does not appear to be able to halt erythropoiesis completely.

Pulmonary vasodilation

Within the lungs, hypoxia is observed to be a potent pulmonary

vasoconstrictor Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vess ...

, due to inhibition of an outward potassium current and activation of inward sodium current leading to pulmonary vascular muscular contraction. However, the effects of hyperoxia do not seem to have a particularly strong vasodilatory effect from the few studies that have been performed on patients with pulmonary hypertension. As a result, an effect appears to be present but minor.

Systemic vasoconstriction

In the systemic vasculature, oxygen serves as a vasoconstrictor, leading to mildly increased blood pressure and decreased cardiac output and heart rate. Hyperbaric conditions do not seem to have a significant impact on these overall physiologic effects. Clinically, this may lead to increased left-to-right shunting in certain patient populations, such as those with

atrial septal defect Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria (upper chambers) of the heart. Some flow is a normal condition both pre-birth and immediately post-birth via the foramen ovale; however, when this d ...

. While the mechanism of the vasoconstriction is unknown, one proposed theory is that increased

reactive oxygen species In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen () p ...

from oxygen therapy accelerates the degradation of endothelial nitric oxide, a vasodilator. These vasoconstrictive effects are thought to be the underlying mechanism helping to abort cluster headaches. Dissolved oxygen in hyperoxic conditions may make also a significant contribution to total gas transport. Home oxygen canisters

Storage and sources

Oxygen can be separated by a number of methods (e.g.,

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

, fractional distillation) to enable immediate or future use. The main methods utilized for oxygen therapy include: # Liquid storage –

Liquid oxygen Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an app ...

is stored in insulateded tanks at low temperature and allowed to

boil A boil, also called a furuncle, is a deep folliculitis, which is an infection of the hair follicle. It is most commonly caused by infection by the bacterium '' Staphylococcus aureus'', resulting in a painful swollen area on the skin caused by ...

(at a temperature of 90.188 K (−182.96 °C)) during use, releasing gaseous oxygen. This method is widely utilized at hospitals due to high oxygen requirements. See Vacuum Insulated Evaporator for more information on this method of storage. # Compressed gas storage – Oxygen gas is compressed in a gas cylinder, which provides a convenient storage method (refrigeration not required). Large oxygen cylinders hold a volume of and can last about two days at a flow rate of 2 litres per minute (LPM). A small portable M6 (B) cylinder holds and weighs about . These tanks can last 4–6 hours with a conserving regulator, which adjust flow based on a person's breathing rate. Conserving regulators may not be effective for patients who breathe through their mouth. # Instant usage – The use of an electrically powered

or a chemical reaction based unit can create sufficient oxygen for immediate personal use. These units (especially the electrically powered versions) are widely used for home oxygen therapy as portable personal oxygen. One particular advantage includes continuous supply without need for bulky oxygen cylinders.

Hazards and risk

Highly concentrated sources of oxygen also increase risk for rapid combustion. Oxygen itself is not flammable, but the addition of concentrated oxygen to a fire greatly increases its intensity, and can aid the combustion of materials that are relatively inert under normal conditions. Fire and explosion hazards exist when concentrated oxidants and fuels are brought together in close proximity, although an ignition event (e.g., heat or spark) is needed to trigger combustion. Concentrated oxygen will allow combustion to proceed rapidly and energetically. Steel pipes and storage vessels used to store and transmit both gaseous and

liquid oxygen Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an app ...

will act as a fuel; and therefore the design and manufacture of oxygen systems requires special training to ensure that ignition sources are minimized. Highly concentrated oxygen in a high-pressure environment can spontaneously ignite hydrocarbons such as oil and grease, resulting in a fire or explosion. The heat caused by rapid pressurization serves as the ignition source. For this reason, storage vessels, regulators, piping and any other equipment used with highly concentrated oxygen must be "oxygen-clean" prior to use to ensure the absence of potential fuels. This does not only apply to pure oxygen; any concentration significantly higher than atmospheric (approximately 21%) carries a potential ignition risk. Some hospitals have instituted "no-smoking" policies which can help keep ignition sources away from medically piped oxygen. These policies do not eliminate the risk of injury among patients with portable oxygen systems, especially among smokers. Other potential sources of ignition include candles, aromatherapy, medical equipment, cooking, and deliberate vandalism.

Delivery

Various devices are used for oxygen administration. In most cases, the oxygen will first pass through a

pressure regulator A pressure regulator is a valve that controls the pressure of a fluid or gas to a desired value, using negative feedback from the controlled pressure. Regulators are used for gases and liquids, and can be an integral device with a pressure setti ...

, used to control the high pressure of oxygen delivered from a cylinder (or other source) to a lower pressure. This lower pressure is then controlled by a

flowmeter Flow measurement is the quantification of bulk fluid movement. Flow can be measured in a variety of ways. The common types of flowmeters with industrial applications are listed below: * a) Obstruction type (differential pressure or variable area) ...

(which may be preset or selectable) which controls the flow at a measured rate (e.g., litres per minute PM. The typical flowmeter range for medical oxygen is between 0 and 15 LPM with some units capable of obtaining up to 25 LPM. Many wall flowmeters using a Thorpe tube design are able to be dialed to "flush" oxygen which is beneficial in emergency situations.

Low-dose oxygen

Many people only require slight increases in inhaled oxygen, rather than pure or near-pure oxygen. These requirements can be met through a number of devices dependent on situation, flow requirements, and personal preference. A

(NC) is a thin tube with two small nozzles inserted into a person's nostrils. It can provide oxygen at low flow rates, 1–6 litres per minute (LPM), delivering an oxygen concentration of 24–40%. There are also a number of face mask options, such as the

simple face mask The simple face mask (SFM) is a basic disposable mask, made of clear plastic, to provide oxygen therapy for patients who are experiencing conditions such as chest pain (possible heart attacks), dizziness, and minor hemorrhages. This mask is onl ...

, often used at between 5 and 10 LPM, capable of delivering oxygen concentrations between 35% and 55%. This is closely related to the more controlled air-entrainment masks, also known as Venturi masks, which can accurately deliver a predetermined oxygen concentration from 24 to 50%. In some instances, a partial rebreathing mask can be used, which is based on a simple mask, but features a reservoir bag, which can provide oxygen concentrations of 40–70% at 5–15 LPM. Demand oxygen delivery systems (DODS) or oxygen resuscitators deliver oxygen only when the person inhales or the caregiver presses a button on the mask (e.g., nonbreathing patient). These systems greatly conserve oxygen compared to steady-flow masks, and are useful in emergency situations when a limited supply of oxygen is available and there is a delay in transporting the person to higher care. Due to utilization of a variety of methods for oxygenation requirements performance differences arise. They are very useful in

CPR Cardiopulmonary resuscitation (CPR) is an emergency procedure consisting of chest compressions often combined with artificial ventilation in an effort to manually preserve intact brain function until further measures are taken to restore sponta ...

, as the caregiver can deliver rescue breaths composed of 100% oxygen with the press of a button. Care must be taken not to over-inflate the person's lungs, for which some systems employ safety valves. These systems may not be appropriate for people who are unconscious or in respiratory distress because of the required respiratory effort.

High flow oxygen delivery

For patients requiring high concentrations of oxygen, a number of devices are available. The most commonly utilized device is the

non-rebreather mask A non-rebreather mask (NRB, non-rebreather, non-rebreather facemask, etc.) is a device used in medicine to assist in the delivery of oxygen therapy. A NRB requires that the patient can breathe unassisted, but unlike a low-flow nasal cannula, the ...

(or reservoir mask). Non-rebreather masks draw oxygen from attached reservoir bags with one-way valves that direct exhaled air out of the mask. If flow rate is not sufficient (~10L/min), the bag may collapse on inspiration. This type of mask is indicated for acute medical emergencies. The delivered F_IO₂ (Inhalation volumetric fraction of molecular oxygen) of this system is 60–80%, depending on oxygen flow and breathing pattern. Another type of device is a humidified high flow

which enables flows exceeding a person's peak inspiratory flow demand to be delivered via nasal cannula, thus providing F_IO₂ of up to 100% because there is no entrainment of room air. This also allows the person to continue to talk, eat, and drink while still receiving therapy. This type of delivery method is associated with greater overall comfort, improved oxygenation, and respiratory rates compared with face mask oxygen. In specialist applications such as aviation, tight-fitting masks can be used. These masks also have applications in

anaesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), a ...

treatment and in

hyperbaric oxygen therapy Hyperbaric medicine is medical treatment in which an ambient pressure greater than sea level atmospheric pressure is a necessary component. The treatment comprises hyperbaric oxygen therapy (HBOT), the medical use of oxygen at an ambient pressure ...

Positive pressure delivery

Patients who are unable to breathe on their own will require positive pressure to move oxygen into their lungs for gaseous exchange to take place. Systems for delivery vary in complexity and cost, starting with a basic pocket mask adjunct which can be used to manually deliver artificial respiration with supplemental oxygen delivered through a mask port. Many

emergency medical service Emergency medical services (EMS), also known as ambulance services or paramedic services, are emergency services that provide urgent pre-hospital treatment and stabilisation for serious illness and injuries and transport to definitive care. ...

members,

first aid First aid is the first and immediate assistance given to any person with either a minor or serious illness or injury, with care provided to preserve life, prevent the condition from worsening, or to promote recovery. It includes initial in ...

personnel, and hospital staff may use a bag-valve-mask (BVM), which is a malleable bag attached to a face mask (or invasive airway such as an

endotracheal tube A tracheal tube is a catheter that is inserted into the Vertebrate trachea, trachea for the primary purpose of establishing and maintaining a patent airway and to ensure the adequate Gas exchange, exchange of oxygen and carbon dioxide. Many diffe ...

laryngeal mask airway A laryngeal mask airway (LMA), also known as laryngeal mask, is a medical device that keeps a patient's Respiratory tract, airway open during anaesthesia or while they are Unconsciousness, unconscious. It is a type of supraglottic airway device. ...

), usually with a reservoir bag attached, which is manually manipulated by the healthcare professional to push oxygen (or air) into the lungs. This is the only procedure allowed for initial treatment of

cyanide poisoning Cyanide poisoning is poisoning that results from exposure to any of a number of forms of cyanide. Early symptoms include headache, dizziness, fast heart rate, shortness of breath, and vomiting. This phase may then be followed by seizures, sl ...

in the UK workplace. o2regulator

Automated versions of the BVM system, known as a

resuscitator A resuscitator is a device using positive pressure to inflate the lungs of an unconscious person who is not breathing, in order to keep them oxygenated and alive. There are three basic types: a ''manual'' version (also known as a ''bag valve mask ...

or pneupac can also deliver measured and timed doses of oxygen directly to people through a facemask or airway. These systems are related to the anaesthetic machines used in operations under general anaesthesia that allow a variable amount of oxygen to be delivered, along with other gases including air,

nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...

and inhalational anaesthetics.

Drug delivery

Oxygen and other compressed gases are used in conjunction with a

nebulizer In medicine, a nebulizer (American English) or nebuliser (British English) is a drug delivery device used to administer medication in the form of a mist inhaled into the lungs. Nebulizers are commonly used for the treatment of asthma, cystic fibro ...

to allow delivery of medications to the upper and/or lower airways. Nebulizers use compressed gas to propel liquid medication into therapeutically sized aerosol droplets for deposition to the appropriate portion of the airway. A typical compressed gas flow rate of 8–10 L/min is used to nebulize medications, saline, sterile water, or a combination these treatments into a therapeutic aerosol for inhalation. In the clinical setting, room air (ambient mix of several gasses),

molecular oxygen There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: * ...

, and

Heliox Heliox is a breathing gas mixture of helium (He) and oxygen (O2). It is used as a medical treatment for patients with difficulty breathing because mixture generates less resistance than atmospheric air when passing through the airways of the lung ...

are the most common gases used to nebulize a bolus treatment or a continuous volume of therapeutic aerosols.

Exhalation filters for oxygen masks

Filtered oxygen masks have the ability to prevent exhaled particles from being released into the surrounding environment. These masks are normally of a closed design such that leaks are minimized and breathing of room air is controlled through a series of one-way valves. Filtration of exhaled breaths is accomplished either by placing a filter on the exhalation port or through an integral filter that is part of the mask itself. These masks first became popular in the Toronto (Canada) healthcare community during the 2003 SARS Crisis. SARS was identified as being respiratory based, and it was determined that conventional oxygen therapy devices were not designed for the containment of exhaled particles. In 2003, the HiOx⁸⁰ oxygen mask was released for sale. The HiOx⁸⁰ mask is a closed design mask that allows a filter to be placed on the exhalation port. Several new designs have emerged in the global healthcare community for the containment and filtration of potentially infectious particles. Other designs include the ISO- oxygen mask, the Flo₂Max oxygen mask, and the O-Mask. Typical oxygen masks allow a person to breathe in a mixture of room air and therapeutic oxygen. However, as filtered oxygen masks use a closed design that minimizes or eliminates the person's contact with and ability to inhale room air, delivered oxygen concentrations in such devices have been found to be elevated, approaching 99% using adequate oxygen flows. Because all exhaled particles are contained within the mask, nebulized medications are also prevented from releasing into the surrounding atmosphere, decreasing the occupational exposure to healthcare staff and other people.

Aircraft

In the United States, most airlines restrict the devices allowed on board an aircraft. As a result, passengers are restricted in what devices they can use. Some airlines will provide cylinders for passengers with an associated fee. Other airlines allow passengers to carry on approved portable concentrators. However, the lists of approved devices varies by airline so passengers may need to check with any airline they are planning to fly on. Passengers are generally not allowed to carry on personal cylinders. In all cases, passengers need to notify the airline in advance of their equipment. Effective May 13, 2009, the Department of Transportation and FAA ruled that a select number of portable oxygen concentrators are approved for use on all commercial flights. FAA regulations require larger airplanes to carry D-cylinders of oxygen for use in case of an emergency.

Oxygen conserving devices

Since the 1980s, devices have been available which conserve stored oxygen by delivering it during the portion of the breathing cycle when it is more effectively used. This has the effect of stored oxygen lasting longer, or a smaller, and therefore lighter, portable oxygen delivery system being practicable. This class of device can also be used with portable oxygen concentrators, making them more efficient. The delivery of supplemental oxygen is most effective if it is made at a point in the breathing cycle when it will be inhaled to the alveoli, where gas transfer occurs. oxygen delivered later in the cycle will be inhaled into physiological dead space, wher it serves no useful purpose as it cannot diffuse into the blood. Oxygen delivered during stages of the breathing cycle in which it is not inhaled is also wasted. A continuous constant flow rate uses a simple regulator, but is inefficient as a high percentage of the delivered gas does not reach the alveoli, and over half is not inhaled at all. A system which accumulates free-flow oxygen during resting and exhalation stages, (reservoir cannulas) makes a larger part of the oxygen available for inhalation, and it will be selectively inhaled during the initial part of inhalation, which reaches furthest into the lungs. A similar function is provided by a mechanical demand regulator which provides gas only during inhalation, but requires some physical effort by the user, and also ventilates dead space with oxygen. A third class of system (pulse dose oxygen conserving device, or demand pulse devices) senses the start of inhalation and provides a metered bolus, which if correctly matched to requirements, will be sufficient and effectively inhaled into the alveoli.Such systems can be pneumatically or electrically controlled. Adaptive demand systems A development in pulse demand delivery are devices that automatically adjust the volume of the pulsed bolus to suit the activity level of the user. This adaptive response in intended to reduce desaturation responses caused by exercise rate variation. Pulsed delivery devices are available as stand alone modules or integrated into a system specifically designed to use compressed gas, liquid oxygen or oxygen concentrator sources. Integrated design usually allows optimisation of the system for the source type at the cost of versatility. Transtracheal oxygen catheters are inserted directly into the trachea through a small opening in the front of the neck for that purpose. The opening is directed downward, towards the bifurcation of the bronchi. Oxygen introduced through the catheter bypasses the dead spaces of the nose, pharynx and upper trachea during inhalation, and during continuous flow, will accumulate in the anatomic dead space at the end of exhalation and be available for immediate inhalation to the alveoli on the following inhalation. This reduces wastage and provides efficiency roughly three times greater than with external continuous flow. This is roughly equivalent to a reservoir cannula. Transtracheal catheters have been found to be effective during rest, exercise and sleep.

Medical uses

Acute conditions

Chronic conditions

Contraindications

Adverse effects

Alternative medicine

Physiologic Effects

Absorption atelectasis

Airway inflammation

Central nervous system effects

Hypercapnea

Immunological effects

Oxidative Stress

Reduction in erythropoiesis

Pulmonary vasodilation

Systemic vasoconstriction

Storage and sources

Hazards and risk

Delivery

Low-dose oxygen

High flow oxygen delivery

Positive pressure delivery

Drug delivery

Exhalation filters for oxygen masks

Aircraft

Oxygen conserving devices

Long term oxygen therapy

See also

References

Further reading