Oxygen therapy, also known as supplemental oxygen, is the use of oxygen as a medical treatment. This can include for low blood oxygen, carbon monoxide toxicity, cluster headaches, and to maintain enough oxygen while inhaled anesthetics are given. Long-term oxygen is often useful in people with chronically low oxygen such as from severe COPD or cystic fibrosis. Oxygen can be given in a number of ways including nasal cannula, face mask, and inside a hyperbaric chamber.
Oxygen is required for normal cell metabolism. Excessively high concentrations can cause oxygen toxicity such as lung damage or result in respiratory failure in those who are predisposed. Higher oxygen concentrations also increase the risk of fires, particularly while smoking, and without humidification can also dry out the nose. The target oxygen saturation recommended depends on the condition being treated. In most conditions a saturation of 94–96% is recommended, while in those at risk of carbon dioxide retention saturations of 88–92% are preferred, and in those with carbon monoxide toxicity or cardiac arrest they should be as high as possible. Air is typically 21% oxygen by volume while oxygen therapy increases this by some amount up to 100%.
The use of oxygen in medicine became common around 1917. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The cost of home oxygen is about US$150 a month in Brazil and US$400 a month in the United States. Home oxygen can be provided either by oxygen tanks or an oxygen concentrator. Oxygen is believed to be the most common treatment given in hospitals in the developed world.
A person wearing a simple face mask
|Synonyms||supplemental oxygen, enriched air|
|AHFS/Drugs.com||FDA Professional Drug Information|
|Drug class||medical gas|
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Oxygen is used as a medical treatment in both chronic and acute cases, and can be used in hospital, pre-hospital or entirely out of hospital.
A common use of supplementary oxygen is in people with chronic obstructive pulmonary disease (COPD), the occurrence of chronic bronchitis or emphysema, a common long-term effect of smoking, who may require additional oxygen to breathe either during a temporary worsening of their condition, or throughout the day and night. It is indicated in people with COPD, with arterial oxygen partial pressure PaO
2 ≤ 55 mmHg (7.3 kPa) or arterial oxygen saturation SaO
2 ≤ 88% and has been shown to increase lifespan.
Oxygen is often prescribed for people with breathlessness, in the setting of end-stage cardiac or respiratory failure, advanced cancer or neurodegenerative disease, despite having relatively normal blood oxygen levels. A 2010 trial of 239 subjects found no significant difference in reducing breathlessness between oxygen and air delivered in the same way.
It may also be indicated for any other people where their injury or illness has caused low oxygen levels, although in this case oxygen flow should be moderated to achieve oxygen saturation levels, based on pulse oximetry (with a target level of 94–96% in most, or 88–92% in people with COPD). Excessively use of oxygen in those who are acutely ill however increases the risk of death. In 2018 recommendations within the British Medical Journal were that oxygen should be stopped if saturations are greater than 96% and should not be started if above 90 to 93%. Exceptions were those with carbon monoxide poisoning, cluster headaches, attacks of sickle cell disease, and pneumothorax.
People who are receiving oxygen therapy for low oxygen following an acute illness or hospitalization should not routinely have a prescription renewal for continued oxygen therapy without a physician's re-assessment of the person's condition. If the person has recovered from the illness, then the hypoxemia is expected to resolve and additional care would be unnecessary and a waste of resources.
Many EMS protocols indicate that oxygen should not be withheld from anyone, while other protocols are more specific or circumspect. However, there are certain situations in which oxygen therapy is known to have a negative impact on a person's condition.
Oxygen should never be given to a person who is suffering from paraquat poisoning unless they are suffering from severe respiratory distress or respiratory arrest, as this can increase the toxicity. (Paraquat poisoning is rare – for example 200 deaths globally from 1958 to 1978). Oxygen therapy is not recommended for people who have suffered pulmonary fibrosis or other lung damage resulting from bleomycin treatment.
High levels of oxygen given to infants causes blindness by promoting overgrowth of new blood vessels in the eye obstructing sight. This is retinopathy of prematurity (ROP).
Oxygen has vasoconstrictive effects on the circulatory system, reducing peripheral circulation and was once thought to potentially increase the effects of stroke. However, when additional oxygen is given to the person, additional oxygen is dissolved in the plasma according to Henry's Law. This allows a compensating change to occur and the dissolved oxygen in plasma supports embarrassed (oxygen-starved) neurons, reduces inflammation and post-stroke cerebral edema. Since 1990, hyperbaric oxygen therapy has been used in the treatments of stroke on a worldwide basis. In rare instances, people receiving hyperbaric oxygen therapy have had seizures. However, because of the aforementioned Henry's Law effect of extra available dissolved oxygen to neurons, there is usually no negative sequel to the event. Such seizures are generally a result of oxygen toxicity, although hypoglycemia may be a contributing factor, but the latter risk can be eradicated or reduced by carefully monitoring the person's nutritional intake prior to oxygen treatment.
Oxygen first aid has been used as an emergency treatment for diving injuries for years. Recompression in a hyperbaric chamber with the person breathing 100% oxygen is the standard hospital and military medical response to decompression illness. The success of recompression therapy as well as a decrease in the number of recompression treatments required has been shown if first aid oxygen is given within four hours after surfacing. There are suggestions that oxygen administration may not be the most effective measure for the treatment of decompression illness and that heliox may be a better alternative.
Care needs to be exercised in people with chronic obstructive pulmonary disease, such as emphysema, especially in those known to retain carbon dioxide (type II respiratory failure). Such people may further accumulate carbon dioxide and decreased pH (hypercapnation) if administered supplemental oxygen, possibly endangering their lives. This is primarily as a result of ventilation–perfusion imbalance (see Effect of oxygen on chronic obstructive pulmonary disease). In the worst case, administration of high levels of oxygen in people with severe emphysema and high blood carbon dioxide may reduce respiratory drive to the point of precipitating respiratory failure, with an observed increase in mortality compared with those receiving titrated oxygen treatment. However, the risk of the loss of respiratory drive are far outweighed by the risks of withholding emergency oxygen, and therefore emergency administration of oxygen is never contraindicated. Transfer from field care to definitive care, where oxygen use can be carefully calibrated, typically occurs long before significant reductions to the respiratory drive.
A 2010 study has shown that titrated oxygen therapy (controlled administration of oxygen) is less of a danger to people with COPD and that other, non-COPD people, may also, in some cases, benefit more from titrated therapy.
Highly concentrated sources of oxygen promote 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 (such as metals) which are relatively inert under normal conditions. Fire and explosion hazards exist when concentrated oxidants and fuels are brought into close proximity; however, an ignition event, such as heat or a spark, is needed to trigger combustion. A well-known example of an accidental fire accelerated by pure oxygen occurred in the Apollo 1 spacecraft in January 1967 during a ground test; it killed all three astronauts. A similar accident killed Soviet cosmonaut Valentin Bondarenko in 1961.
2 will allow combustion to proceed rapidly and energetically. Steel pipes and storage vessels used to store and transmit both gaseous and liquid oxygen will act as a fuel; and therefore the design and manufacture of O
2 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 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 apply only to pure oxygen; any concentration significantly higher than atmospheric (approximately 21%) carries a potential risk.
Hospitals in some jurisdictions, such as the UK, now operate "no-smoking" policies, which although introduced for other reasons, support the aim of keeping ignition sources away from medical piped oxygen. Recorded sources of ignition of medically prescribed oxygen include candles, aromatherapy, medical equipment, cooking, and unfortunately, deliberate vandalism. Smoking of pipes, cigars and cigarettes is of special concern. These policies do not entirely eliminate the risk of injury with portable oxygen systems, especially if compliance is poor.
Some practitioners of alternative medicine have promoted "oxygen therapy" as a cure for many human ailments including AIDS, Alzheimer's disease and cancer. The procedure may include injecting hydrogen peroxide, oxygenating blood, or administering oxygen under pressure to the rectum, vagina, or other bodily opening. 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.
Oxygen can be separated by a number of methods, including chemical reaction and fractional distillation, and then either used immediately or stored for future use. The main types of sources for oxygen therapy are:
Various devices are used for administration of oxygen. In most cases, the oxygen will first pass through a pressure regulator, 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, which may be preset or selectable, and this controls the flow in a measure such as litres per minute (lpm). The typical flowmeter range for medical oxygen is between 0 and 15 lpm with some units able to obtain up to 25 liters per minute. Many wall flowmeters using a Thorpe tube design are able to be dialed to "flush" which is beneficial in emergency situations.
Many people only require a slight increase in oxygen in the air they breathe, rather than pure or near-pure oxygen. This can be delivered through a number of devices dependent on the situation, the flow required and in some instances person's preference.
A nasal cannula (NC) is a thin tube with two small nozzles that protrude into the person's nostrils. It can only comfortably provide oxygen at low flow rates, 2–6 litres per minute (LPM), delivering a concentration of 24–40%.
There are also a number of face mask options, such as the simple face mask, often used at between 5 and 8 LPM, with a concentration of oxygen to the person of between 28% and 50%. This is closely related to the more controlled air-entrainment masks, also known as Venturi masks, which can accurately deliver a predetermined oxygen concentration to the trachea up to 40%.
In some instances, a partial rebreathing mask can be used, which is based on a simple mask, but featuring a reservoir bag, which increases the provided oxygen concentration to 40–70% oxygen at 5–15 LPM.
Non-rebreather masks draw oxygen from attached reservoir bags, with one-way valves that direct exhaled air out of the mask. When properly fitted and used at flow rates of 8–10 LPM or higher, they deliver close to 100% oxygen. This type of mask is indicated for acute medical emergencies.
Demand oxygen delivery systems (DODS) or oxygen resuscitators deliver oxygen only when the person inhales, or, in the case of a non-breathing person, the caregiver presses a button on the mask. These systems greatly conserve oxygen compared to steady-flow masks, which is useful in emergency situations when a limited supply of oxygen is available and there is a delay in transporting the person to higher care. They are very useful in performing CPR, 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, and some systems employ safety valves to help prevent this. These systems may not be appropriate for people who are unconscious or those in respiratory distress, because of the effort required to breathe from them.
In cases where the person requires a high concentration of up to 100% oxygen, a number of devices are available, with the most common being the non-rebreather mask (or reservoir mask), which is similar to the partial rebreathing mask except it has a series of one-way valves preventing exhaled air from returning to the bag. There should be a minimum flow of 10 L/min. The delivered FIO2 (Inhalation volumetric fraction of molecular oxygen) of this system is 60–80%, depending on the oxygen flow and breathing pattern. Another type of device is a humidified high flow nasal cannula which enables flows exceeding a person's peak inspiratory flow demand to be delivered via nasal cannula, thus providing FIO2 of up to 100% because there is no entrainment of room air, even with the mouth open. This also allows the person to continue to talk, eat and drink while still receiving the therapy. This type of delivery method is associated with greater overall comfort, and improved oxygenation and respiratory rates than with face mask oxygen.
People 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 delivering this vary in complexity (and cost), starting with a basic pocket mask adjunct which can be used by a basically trained first aider to manually deliver artificial respiration with supplemental oxygen delivered through a port in the mask.
Many emergency medical service and first aid personnel, as well as hospitals, will use a bag-valve-mask (BVM), which is a malleable bag attached to a face mask (or invasive airway such as an endotracheal tube or laryngeal mask airway), 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 in the UK workplace.
Automated versions of the BVM system, known as a resuscitator or pneupac can also deliver measured and timed doses of oxygen direct to people through a facemask or airway. These systems are related to the anaesthetic machines used in operations under general anaesthesia that allows a variable amount of oxygen to be delivered, along with other gases including air, nitrous oxide and inhalational anaesthetics.
Oxygen and other compressed gasses are used in conjunction with a nebulizer to allow the delivery of medications to the upper and/or lower airways. Nebulizers use compressed gas to propel liquid medication into an aerosol, with specific therapeutically sized droplets, for deposition in the appropriate, desired 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 mixture of the preceding into a therapeutic aerosol for inhalation. In the clinical setting room air (ambient mix of several gasses), molecular oxygen, and Heliox are the most common gases used to nebulize a bolus or a continuous volume of therapeutic aerosols.
Filtered oxygen masks have the ability to prevent exhaled, potentially infectious 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. Common practices of having suspected people wear a surgical mask was confounded by the use of standard oxygen therapy equipment. 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-O
2 oxygen mask, the Flo2Max oxygen mask, and the O-Mask. The use of oxygen masks that are capable of filtering exhaled particles is gradually becoming a recommended practice for pandemic preparation in many jurisdictions.
Typical oxygen masks allow the person to breathe in room air in addition to their therapeutic oxygen, but because 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 to the person have been found to be higher, approaching 99% using adequate oxygen flows. Because all exhaled particles are contained within the mask, nebulized medications are also prevented from being released into the surrounding atmosphere, decreasing the occupational exposure to healthcare staff and other people.
In the United States, most airlines restrict the devices allowed on board 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 need to check with any airline they are planning to fly on. Passengers are generally not allowed to carry on their own 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 an emergency.
(As of November 2014) Positive Testing Results: AirSep FreeStyle, AirSep LifeStyle, AirSep Focus, AirSep Freestyle 5, (Caire) SeQual eQuinox / Oxywell (model 4000), Delphi RS-00400 / Oxus RS-00400, DeVilbiss Healthcare iGo, Inogen One, Inogen One G2, lnogen One G3, lnova Labs LifeChoice Activox, International Biophysics LifeChoice / lnova Labs LifeChoice, Invacare XPO2, Invacare Solo 2, Oxylife Independence Oxygen Concentrator, Precision Medical EasyPulse, Respironics EverGo, Respironics SimplyGo, Sequal Eclipse, SeQual SAROS, VBox Trooper
Asbestosis is long term inflammation and scarring of the lungs due to asbestos fibres. Symptoms may include shortness of breath, cough, wheezing, and chest tightness. Complications may include lung cancer, mesothelioma, and pulmonary heart disease.Asbestosis is caused by breathing in asbestos fibers. Generally it requires a relatively large exposure over a long period of time. Such levels of exposure typically only occur in those who work with the material. All types of asbestos fibers are associated with an increased risk. It is generally recommended that currently existing asbestos be left undisturbed. Diagnosis is based upon a history of exposure together with medical imaging. Asbestosis is a type of interstitial pulmonary fibrosis.There is no specific treatment. Recommendations may include influenza vaccination, pneumococcal vaccination, oxygen therapy, and stopping smoking. Asbestosis affected about 157,000 people and resulted in 3,600 deaths in 2015. Asbestos use has been banned in a number of countries in an effort to prevent disease.Beauty salon
A beauty salon or beauty parlor (beauty parlour), or sometimes beauty shop, is an establishment dealing with cosmetic treatments for men and women. Other variations of this type of business include hair salons and spas.
There is a distinction between a beauty salon and a hair salon and although many small businesses do offer both sets of treatments; beauty salons provide extended services related to skin health, facial aesthetics, foot care, nail manicures, aromatherapy — even meditation, oxygen therapy, mud baths and many other services.Demand valve oxygen therapy
Demand Valve Oxygen Therapy (DVOT) is a way of delivering high flow oxygen therapy using a device that only delivers oxygen when the patient breathes in and shuts off when they breathe out. DVOT is commonly used to treat conditions such as cluster headache, which affects up to four in 1000 people (0.4%), and is a recommended first aid procedure for several diving disorders. It is also a recommended prophylactic for decompression sickness in the event of minor omitted decompression without symptoms.Diving 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 breathing gas for the occupants.
There are two main functions for diving chambers:
as a simple form of submersible vessel to transport divers underwater and to provide a temporary base and retrieval system in the depths;
as a land, ship or offshore platform-based hyperbaric chamber or system, to artificially reproduce the hyperbaric conditions under the sea. Internal pressures above normal atmospheric pressure are provided for diving-related applications such as saturation diving and diver decompression, and non-diving medical applications such as hyperbaric medicine.Diving disorders
Diving disorders, or diving related medical conditions, are conditions associated with underwater diving, and include both conditions unique to underwater diving, and those that also occur during other activities. This second group further divides into conditions caused by exposure to ambient pressures significantly different from surface atmospheric pressure, and a range of conditions caused by general environment and equipment associated with diving activities.
Disorders particularly associated with diving include those caused by variations in ambient pressure, such as barotraumas of descent and ascent, decompression sickness and those caused by exposure to elevated ambient pressure, such as some types of gas toxicity. There are also non-dysbaric disorders associated with diving, which include the effects of the aquatic environment, such as drowning, which also are common to other water users, and disorders caused by the equipment or associated factors, such as carbon dioxide and carbon monoxide poisoning. General environmental conditions can lead to another group of disorders, which include hypothermia and motion sickness, injuries by marine and aquatic organisms, contaminated waters, man-made hazards, and ergonomic problems with equipment. Finally there are pre-existing medical and psychological conditions which increase the risk of being affected by a diving disorder, which may be aggravated by adverse side effects of medications and other drug use.
Treatment depends on the specific disorder, but often includes oxygen therapy, which is standard first aid for most diving accidents, and is hardly ever contra-indicated for a person medically fit to dive, and hyperbaric therapy is the definitive treatment for decompression sickness. Screening for medical fitness to dive can reduce some of the risk for some of the disorders.Diving medicine
Diving medicine, also called undersea and hyperbaric medicine (UHB), is the diagnosis, treatment and prevention of conditions caused by humans entering the undersea environment. It includes the effects on the body of pressure on gases, the diagnosis and treatment of conditions caused by marine hazards and how relationships of a diver's fitness to dive affect a diver's safety.
Hyperbaric medicine is a corollary field associated with diving, since recompression in a hyperbaric chamber is used as a treatment for two of the most significant diving-related illnesses, decompression sickness and arterial gas embolism.
Diving medicine deals with medical research on issues of diving, the prevention of diving disorders, treatment of diving accidents and diving fitness. The field includes the effect of breathing gases and their contaminants under high pressure on the human body and the relationship between the state of physical and psychological health of the diver and safety.
In diving accidents it is common for multiple disorders to occur together and interact with each other, both causatively and as complications.
Diving medicine is a branch of occupational medicine and sports medicine, and an important part of diver education.Gangrene
Gangrene is a type of tissue death caused by a lack of blood supply. Symptoms may include a change in skin color to red or black, numbness, swelling, pain, skin breakdown, and coolness. The feet and hands are most commonly affected. Certain types may present with a fever or sepsis.Risk factors include diabetes, peripheral arterial disease, smoking, major trauma, alcoholism, HIV/AIDS, frostbite, and Raynaud's syndrome. It can be classified as dry gangrene, wet gangrene, gas gangrene, internal gangrene, and necrotizing fasciitis. The diagnosis of gangrene is based on symptoms and supported by tests such as medical imaging.Treatment may involve surgery to remove the dead tissue, antibiotics to treat any infection, and efforts to address the underlying cause. Surgical efforts may include debridement, amputation, or the use of maggot therapy. Efforts to treat the underlying cause may include bypass surgery or angioplasty. In certain cases, hyperbaric oxygen therapy may be useful. How commonly the condition occurs is unknown.Hyperbaric medicine
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 higher than atmospheric pressure, and therapeutic recompression for decompression illness, intended to reduce the injurious effects of systemic gas bubbles by physically reducing their size and providing improved conditions for elimination of bubbles and excess dissolved gas.
The equipment required for hyperbaric oxygen treatment consists of a pressure chamber, which may be of rigid or flexible construction, and a means of delivering 100% oxygen. Operation is performed to a predetermined schedule by trained personnel who monitor the patient and may adjust the schedule as required. HBOT found early use in the treatment of decompression sickness, and has also shown great effectiveness in treating conditions such as gas gangrene and carbon monoxide poisoning. More recent research has examined the possibility that it may also have value for other conditions such as cerebral palsy and multiple sclerosis, but no significant evidence has been found.
Therapeutic recompression is usually also provided in a hyperbaric chamber. It is the definitive treatment for decompression sickness and may also be used to treat arterial gas embolism caused by pulmonary barotrauma of ascent. In emergencies divers may sometimes be treated by in-water recompression if a chamber is not available and suitable diving equipment to reasonably secure the airway is available.
A number of hyperbaric treatment schedules have been published over the years for both therapeutic recompression and hyperbaric oxygen therapy for other conditions.Hyperbaric nursing
Hyperbaric nursing is a nursing specialty involved in the care of patients receiving hyperbaric oxygen therapy. The National Board of Diving and Hyperbaric Medical Technology offers certification in hyperbaric nursing as a Certified Hyperbaric Registered Nurse (CHRN). The professional nursing organization for hyperbaric nursing is the Baromedical Nurses Association.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 placed in the nostrils and from which a mixture of air and oxygen flows. The other end of the tube is connected to an oxygen supply such as a portable oxygen generator, or a wall connection in a hospital via a flowmeter. The cannula is generally attached to the patient by way of the tube hooking around the patient's ears or by elastic head band. The earliest, and most widely used form of adult nasal cannula carries 1–5 litres of oxygen per minute.
Cannulae with smaller prongs intended for infant or neonatal use can carry less than one litre per minute. Flow rates of up to 60 litres of air/oxygen per minute can be delivered through wider bore humidified nasal cannula.
The nasal cannula was invented by Wilfred Jones and patented in 1949 by his employer, BOC.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. An NRB requires that the patient can breathe unassisted, but unlike low flow nasal cannula, the NRB allows for the delivery of higher concentrations of oxygen.Osteoradionecrosis
Osteoradionecrosis (ORN) is a serious complication associated with the use of radiotherapy in the management of mouth cancer which can result in infection and possibly pathological jaw fractures. It is defined as exposed radiated bone that fails to heal without any evidence of persisting tumour. Reported prevalence varies from 0.4% to 56%. Modern radiotherapy has changed significantly and more modest occurrences have been reported recently, 4.3% over 10 years and 8% over 30 years. A significant change in radiotherapy has been the development of Intensity-modulated radiation therapy (IMRT). The development of proton beam radiation therapy may also help.
Bone is relatively radio-resistant compared to other tissues due its blood supply and limited reparative ability and poses a problem when irradiated. ORN is more common in the posterior mandible due to a reduced blood supply. Additional risk factors include: poor dental health, tobacco and alcohol use, operative surgery involving mucosa and bone in the site of the radiotherapy and high dose radiation. ORN can occur spontaneously, due to periodontal and apical disease and possibly after trauma induced by dentures, or after surgery or tooth extraction. A balance of tumour eradication and normal tissue preservation must be reached to achieve cure without further debilitating the patient.Oxygen saturation (medicine)
Oxygen saturation is the fraction of [oxygen]-saturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal blood oxygen levels in humans are considered 95–100 percent. If the level is below 90 percent, it is considered low resulting in hypoxemia. Blood oxygen levels below 80 percent may compromise organ function, such as the brain and heart, and should be promptly addressed. Continued low oxygen levels may lead to respiratory or cardiac arrest. Oxygen therapy may be used to assist in raising blood oxygen levels. Oxygenation occurs when oxygen molecules (O2) enter the tissues of the body. For example, blood is oxygenated in the lungs, where oxygen molecules travel from the air and into the blood. Oxygenation is commonly used to refer to medical oxygen saturation.Portable oxygen concentrator
A portable oxygen concentrator (POC) is a device used to provide oxygen therapy to people that require greater oxygen concentrations than the levels of ambient air. It is similar to a home oxygen concentrator (OC), but is smaller in size and more mobile. They are small enough to carry and many are now FAA-approved for use on airplanes.Smoke inhalation
Smoke inhalation is the primary cause of death for victims of fires. The inhalation or exposure to hot gaseous products of combustion can cause serious respiratory complications.Some 50–80% of fire deaths are the result of smoke inhalation injuries, including burns to the respiratory system. The hot smoke injures or kills by a combination of thermal damage, poisoning and pulmonary irritation and swelling, caused by carbon monoxide, cyanide and other combustion products.Transdermal continuous oxygen therapy
Transdermal Continuous Oxygen Therapy (TCOT, also known as Transdermal Continuous Oxygen Wound Therapy) is a wound closure technique for chronic and acute wounds which blankets a wound in oxygen on a 24-hour basis until the wound heals. Unlike hyperbaric oxygen treatment for chronic wounds, oxygen treatment used in this therapy is not systemic in nature and treats only the wound area. This treatment differs from topical oxygen treatments, as topical oxygen typically involves sporadic treatments of 1–3 hours several times per week, while TCOT treatment is 24/7 by nature.Undersea and Hyperbaric Medical Society
The Undersea and Hyperbaric Medical Society (UHMS) is an organization based in the US which supports research on matters of hyperbaric medicine and physiology, and provides a certificate of added qualification for physicians with an unrestricted license to practice medicine and for limited licensed practitioners, at the completion of the Program for Advanced Training in Hyperbaric Medicine. They support an extensive library and are a primary source of information for diving and hyperbaric medicine physiology worldwide.Valsalva maneuver
The Valsalva maneuver is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth, pinching one's nose shut while pressing out as if blowing up a balloon. Variations of the maneuver can be used either in medical examination as a test of cardiac function and autonomic nervous control of the heart, or to clear the ears and sinuses (that is, to equalize pressure between them) when ambient pressure changes, as in diving, hyperbaric oxygen therapy, or air travel.The technique is named after Antonio Maria Valsalva, a seventeenth-century physician and anatomist from Bologna whose principal scientific interest was the human ear. He described the Eustachian tube and the maneuver to test its patency (openness). He also described the use of this maneuver to expel pus from the middle ear.
A modified version is done by expiring against a closed glottis. This will elicit the cardiovascular responses described below but will not force air into the Eustachian tubes.Venturi mask
The venturi mask, also known as an air-entrainment mask, is a medical device to deliver a known oxygen concentration to patients on controlled oxygen therapy. The mask was invented by Moran Campbell at McMaster University Medical School as a replacement for intermittent oxygen treatment, a practice he described as "bringing a drowning man to the surface- occasionally".
Venturi masks are considered high-flow oxygen therapy devices. This is because venturi masks are able to provide total inspiratory flow at a specified FiO2 to patients therapy. The kits usually include multiple jets, which are usually color-coded, in order to set the desired FiO2.
Other brands of masks have a rotating attachment that controls the air entrainment window, affecting the concentration of oxygen. This system is often used with air-entrainment nebulizers to provide humidification and oxygen therapy.
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