Non-rebreather mask
Encyclopedia
A non-rebreather mask, or NRB, is a device used in medical emergencies
that require 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
.
. Before an NRB is placed on the patient, the reservoir bag is inflated to greater than two-thirds full of oxygen, at a rate of 15 liters per minute (lpm). Approximately ¹⁄₃ of the air from the reservoir is depleted as the patient inhales, and it is then replaced by the flow from the O2 supply. If the bag becomes completely deflated, the patient will no longer have a source of air to breathe.
Exhaled air is directed through a one-way valve
in the mask, which prevents the inhalation of room air and the re-inhalation of exhaled air. The valve, along with a sufficient seal around the patient's nose and mouth, allows for the administration of high concentrations of oxygen, 60–90% O2.
Strictly, "non-rebreather" masks are "partial-rebreather" (PRB) masks; ideally, a non-rebreather mask would not permit air from the surrounding environment to be inhaled. However, since not all of the exhaled air is completely removed by the one-way valve and the seal created by the mask is imperfect, intake of some exhaled and outside air is unavoidable.
, chronic airway limitation/chronic obstructive pulmonary disease
s, smoke inhalation
, and carbon monoxide poisoning
, or any other patients who require high-flow oxygen, but do not require breathing assistance. Patients uncomfortable with having a mask on their face, such as those with claustrophobia
, or patients with injuries to the mouth are more likely to benefit from a nasal cannula
, or passive ("blow-by") oxygen. Patients who are unable to breathe on their own would require an active breathing device, such as a bag valve mask
or endotracheal tube.
Medical emergency
A medical emergency is an injury or illness that is acute and poses an immediate risk to a person's life or long term health. These emergencies may require assistance from another person, who should ideally be suitably qualified to do so, although some of these emergencies can be dealt with by the...
that require oxygen therapy
Oxygen therapy
Oxygen therapy is the administration of oxygen as a medical intervention, which can be for a variety of purposes in both chronic and acute patient care...
. An NRB requires that the patient can breathe unassisted, but unlike low flow nasal cannula
Nasal cannula
The nasal cannula is a device used to deliver supplemental oxygen or airflow to a patient or person in need of respiratory help. This device consists of a plastic tube which fits behind the ears, and a set of two prongs which are placed in the nostrils. Oxygen flows from these prongs...
, the NRB allows for the delivery of higher concentrations of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
.
Design
The non-rebreather mask covers both the nose and mouth of the patient and attaches with the use of an elastic cord around the patient's head. The NRB has an attached reservoir bag, typically 1.5 liters, that connects to an external oxygen tankOxygen tank
An oxygen tank is a storage vessel for oxygen, which is either held under pressure in gas cylinders or as liquid oxygen in a cryogenic storage tank.Oxygen tanks are used to store gas for:* industrial processes including the manufacture of steel and monel...
. Before an NRB is placed on the patient, the reservoir bag is inflated to greater than two-thirds full of oxygen, at a rate of 15 liters per minute (lpm). Approximately ¹⁄₃ of the air from the reservoir is depleted as the patient inhales, and it is then replaced by the flow from the O2 supply. If the bag becomes completely deflated, the patient will no longer have a source of air to breathe.
Exhaled air is directed through a one-way valve
Check valve
A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid to flow through it in only one direction....
in the mask, which prevents the inhalation of room air and the re-inhalation of exhaled air. The valve, along with a sufficient seal around the patient's nose and mouth, allows for the administration of high concentrations of oxygen, 60–90% O2.
Strictly, "non-rebreather" masks are "partial-rebreather" (PRB) masks; ideally, a non-rebreather mask would not permit air from the surrounding environment to be inhaled. However, since not all of the exhaled air is completely removed by the one-way valve and the seal created by the mask is imperfect, intake of some exhaled and outside air is unavoidable.
Usage
The non-rebreather mask is utilized for patients with physical traumaPhysical trauma
Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
, chronic airway limitation/chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...
s, smoke inhalation
Smoke inhalation
Smoke inhalation is the primary cause of death in victims of indoor fires.Smoke inhalation injury refers to injury due to inhalation or exposure to hot gaseous products of combustion. This can cause serious respiratory complications....
, and carbon monoxide poisoning
Carbon monoxide poisoning
Carbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect...
, or any other patients who require high-flow oxygen, but do not require breathing assistance. Patients uncomfortable with having a mask on their face, such as those with claustrophobia
Claustrophobia
Claustrophobia is the fear of having no escape and being closed in small spaces or rooms...
, or patients with injuries to the mouth are more likely to benefit from a nasal cannula
Nasal cannula
The nasal cannula is a device used to deliver supplemental oxygen or airflow to a patient or person in need of respiratory help. This device consists of a plastic tube which fits behind the ears, and a set of two prongs which are placed in the nostrils. Oxygen flows from these prongs...
, or passive ("blow-by") oxygen. Patients who are unable to breathe on their own would require an active breathing device, such as a bag valve mask
Bag valve mask
A bag valve mask is a hand-held device used to provide positive pressure ventilation to a patient who is not breathing or who is breathing inadequately. The device is a normal part of a resuscitation kit for trained professionals, such as ambulance crew...
or endotracheal tube.