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Oxygen therapy is the administration of oxygen as a therapeutic modality. Oxygen therapy benefits the patient by increasing the supply of Oxygen to the lungs and thereby increasing the availability of oxygen to the body tissues. Appropriate levels of oxygen are vital to support cell respiration. High blood and tissue levels of oxygen can be helpful or damaging, depending on circumstances. Hyperbaric Oxygen Therapy is the use of high levels of oxygen for treatment of specific diseases. High levels of oxygen given to neonates causes blindness by promoting overgrowth of new blood vessels in the eye obstructing sight. High levels of oxygen in patients with severe emphysema and high blood carbon dioxide reduces respiratory drive which can precipitate retention of more carbon dioxide. Oxygen first aid specifically refers to the use of oxygen in a first aid setting. Oxygen may provide relief in patients with Chest Pain and Dyspnea (shortness of breath). Care needs to be exercised in patients with Chronic Obstructive Pulmonary Disease , especially in those known to retain Carbon Dioxide (type II respiratory failure). For this reason, some jurisdictions require medical approval for emergency oxygen administration. Home or '''domiciliary oxygen therapy''' refers to the administration of oxygen as ongoing therapy, either continuously or intermittently. Most commonly patients on home oxygen therapy have severe chronic obstructive pulmonary disease caused by smoking. OXYGEN SOURCES AND DELIVERY There are three typical sources of oxygen used therapeutically: # Liquid oxygen is contained in pressure tanks. It has to be evaporated into a gas for breathing. Large tanks are used by hospitals. Small tanks can be used domestically. Liquid oxygen tanks are refilled by liquid oxygen suppliers. # Cylinders contain compressed gaseous oxygen. Small cylinders are used for first aid and for home oxygen patients when mobility is required. Cylinders are refilled by a gas supplier. # Concentrators are electrically powered devices which remove nitrogen from room air. They are most commonly used in a domestic situation, because they do not need refilling. Oxygen is most often delivered as continuous gaseous flow, measured in litres per minute. ADMINISTRATION Various devices are used for administration of oxygen. # The Nasal Cannula (NC) is nothing more than a thin tube with two small nozzles that fit neatly into the patients nostrils. It can only provide oxygen at low flow rates, 2-6 litres per minute (lpm), delivering a concentration of 28-44%. It is often used in elderly patients, or patients who can benefit from oxygen therapy but do not require it to the degree of wearing an uncomfortable mask. It is especially useful in those patients where Vasoconstriction could negatively impact their condition, such as those suffering from Stroke s, or "brain attacks." Use of the NC at relatively high rates can cause uncomfort by drying the patient's nasal passages. # The Simple Face Mask (SFM) is a basic mask used for non-life-threatening conditions but which may progress in time, such as chest pain (possible heart attacks), dizziness, and minor Haemorrhage s. It is often set to deliver oxygen at about 6-10 (lpm), there is no "standard". The oxygen concentration delivered by this device is utterly dependent upon the amount of ordinary air that mixes with it the patient breathes. The air mixing is determined by how much air any individual is breathing, at the moment, and the fit of the mask. Oxygen concentrations can vary wildly. # The Non-rebreather Mask (NRB) is utilized for patients with multiple trauma injuries, chronic airway limitation/chronic obstructive pulmonary diseases, smoke inhalation, and carbon monoxide poisoning, or any other patient that requires high-flow oxygen, but does not require breathing assistance. It has an attached reservoir bag where oxygen fills in between breaths, and a valve that largely prevents the inhalation of room or exhaled air. This allows the administration of high concentrations of oxygen, between 80-100%. This device is set to 12-15 lpm, or at least enough to keep the reservoir inflated between breaths. Stictly, "Non-rebreather" masks are "partial-rebreather" (PRB) masks; a non-rebreather mask would ideally not permit air from the surrounding environment to be inhaled. However, since the only NRM or PRM's in current use are disposable cheap plastic, the fit of the mask is often inadequate to avoid air mixture. Additionally, since most medical practitioners are not experts in oxygen delivery systems, patients who breath abnormally large amounts of air require very large flow rates for high concentrations of oxgyen to be given. 40 - 100 LPM are not uncommonly needed in this case. # The Bag-valve-mask (BVM) is used for patients in critical condition who are either breathing extremely inefficiently, or not breathing at all (respiratory arrest). An oxygen reservoir bag is attached to a central cylindrical bag, attached to a valved mask that administers almost 100% concentration oxygen at 8-15 lpm. The central bag is squeezed manually to deliver a "breath" to the patient, or assist them in breathing by doing some of the work for the lungs. # The Pocket Mask is a small device that can be carried on one's person. It is used for the same patients that the BVM is indicated for, but instead of delivering breaths by squeezing a reservoir, the care provider must actually exhale into the mask. Pocket masks normally have one-way valves built into them to protect the provider from the patient's potentially Infectious Body Substance s. Many masks also have an oxygen intake built-in, allowing for administration of 50-60% oxygen. Without being hooked up to an external line, exhaled air from the provider can still provide sufficient oxygen to live (room air is approximately 21%, exhaled air is approximately 16%). The pocket mask should only be used when a BVM is unavailable, so it typically sees use from bystanders performing CPR, not medical professionals with adequate equipment. Furthermore, some devices provide specialized oxygen delivery: #A Nebulizer , in addition to delivering high concentration oxygen, can also deliver certain drugs such as Albuterol or Epinephrine into the airways by creating a vapor-mist from the liquid form of the drug. These are often used for patients experiencing Asthma attacks, Anaphylactic Shock or other forms of breathing difficulty. #A , including performance of Surgery . Aviators type Oxygen Mask s and other specialized masks are used in hyperbaric chambers. NEGATIVE EFFECTS Although most EMS jurisdictions hold that oxygen should not be withheld from any patient, there are certain situation in which oxygen therapy can have a negative impact on a patients condition. Oxygen has Vasoconstrictive effects on the circulatory system, reducing peripheral circulation and potentially increasing the effects of Stroke . Certain types of Chronic Obstructive Pulmonary Diseases can be aggravated by the application of oxygen. Hyperbaric oxygen therapy can cause life-threatening gran mal seizures. Some jurisdictions require that oxygen should not be given to children or people suffering from certain long-term lung conditions by first-responders without medical consultation. SEE ALSO EXTERNAL LINKS
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