Respiratory CareFrequently Asked Questions |
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| How does the respiratory system function? What are the common respiratory disorders? What is Obstructive Sleep Apnea? What is Non-Invasive Ventilation? What are Allergic and Nonallergic Nasal Congestions? What is the difference between acute and chronic sinusitis? ^top |
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| How does the respiratory system function? The primary function of the respiratory
system is to supply the blood with oxygen in order for the blood
to deliver oxygen to all parts of the body. The respiratory system
does this through breathing. When we breathe, we inhale oxygen and
exhale carbon dioxide. This exchange of gases is the respiratory
system's means of getting oxygen to the blood. Respiration is achieved through the mouth,
nose, trachea, lungs, and diaphragm. Oxygen enters the respiratory
system through the mouth and the nose. The oxygen then passes through
the larynx (where speech sounds are produced) and the trachea which
is a tube that enters the chest cavity. In the chest cavity, the
trachea splits into two smaller tubes called the bronchi. Each bronchus
then divides again forming the bronchial tubes. The bronchial tubes
lead directly into the lungs where they divide into many smaller
tubes which connect to tiny sacs called alveoli. The average adult's
lungs contain about 600 million of these spongy, air-filled sacs
that are surrounded by capillaries. The inhaled oxygen passes into
the alveoli and then diffuses through the capillaries into the arterial
blood. Meanwhile, the waste-rich blood from the veins releases its
carbon dioxide into the alveoli. The carbon dioxide follows the
same path out of the lungs when you exhale. The diaphragm's job is to help pump the carbon dioxide out of the lungs and pull the oxygen into the lungs. The diaphragm is a sheet of muscles that lies across the bottom of the chest cavity. As the diaphragm contracts and relaxes, breathing takes place. When the diaphragm contracts, oxygen is pulled into the lungs. When the diaphragm relaxes, carbon dioxide is pumped out of the lungs. ^top What are the common respiratory disorders? Sleep apnea, infant jaundice and apnea, chronic obstructive pulmonary disease are just some of the respiratory afflictions that affect the human body. ^top
^top What is Obstructive Sleep Apnea? Obstructive Sleep Apnea (OSA) is a life threatening and life altering condition that occurs when a person repeatedly stops breathing during sleep because his or her airway collapses and prevents air from getting into the lungs. Sleep is repeatedly disrupted by apneas, depriving OSA sufferers from the deepest, most restful stages of sleep. Apneas may occur more than 20 times every hour. A person with OSA never feels rested because they never have normal sleep. The lack of sleep affects daytime alertness and one’s ability to function well throughout the day. The low oxygen levels associated with OSA, and the effort required to breathe during the night, put a strain on the cardiovascular system. Ultimately, OSA takes its toll on the individual’s quality of life. ^top Newborn babies go through many changes in the first few weeks of life, including significant brain development. Some babies, especially those born premature, may need special care while the part of the brain that controls breathing continues to grow. These infants could suffer from a condition known as infant apnea. All infants have some apnea, but when the apnea is long or if it happens frequently, there may be a problem. ^top Insomnia can be a disease, or most often, it is a symptom of another underlying disease. People who suffer from insomnia have trouble falling asleep, wake frequently during the night, have difficulty returning to sleep, wake too early in the morning and find sleep unrefreshing. Sleep experts consider stress the
most common cause of short-term sleeping difficulties. Forty-eight
percent of Americans report occasional insomnia, while 22 percent
experience insomnia every night or almost every night. Women are
1.3 times more likely to report insomnia than men. People over age
65 are 1.5 times more likely to complain of insomnia than younger
people. Divorced, widowed and separated people, on average, report
more episodes of insomnia than married or single people. ^top Ventilators are used commonly in the operating theatre and in the ICU to deliver mechanical ventilation to the lungs. In the operating theatre, ventilation is in anaesthetized and often pharmacologically paralysed patients with predominantly normal lungs. These ventilators are relatively simple and are designed to deliver varying concentrations of oxygen, air, nitrous oxide and volatile agents to patients through an anaesthetic circuit. In the ICU, ventilators provide respiratory support to patients with respiratory failure. Respiratory failure is a state in which the pulmonary oxygen uptake is so severely disturbed that the supply of oxygen to the tissues and/or the removal of carbon dioxide from them is inadequate. Respiratory failure can be caused by relative hypoventilation, characterized by an increase in arterial carbon dioxide tension, or failure of diffusion at the alveolar–capillary membrane, characterized by decreased arterial oxygen tension. ^top People with asthma, emphysema, chronic bronchitis, occupational lung disease, lung cancer, cystic fibrosis, or congestive heart failure may use oxygen therapy. There are three common ways of providing oxygen therapy. Compressed Gas – Oxygen is stored under pressure in a cylinder equipped with a regulator that controls the flow rate. Because the flow of oxygen out of the cylinder is constant, an oxygen-conserving device may be attached to the system to avoid waste. This device releases the gas only when you inhale and cuts it off when you exhale. Oxygen can be provided in a small cylinder that can be carried with you, but the large tanks are heavy and are only suitable for stationary use. Liquid Oxygen – Oxygen is stored as a very cold liquid in a vessel very similar to a thermos. When released, the liquid converts to a gas and you breathe it in just like the compressed gas. This storage method takes up less space than the compressed gas cylinder. Liquid oxygen is more expensive than the compressed gas, and the vessel vents when not in use. An oxygen-conserving device may be built into the vessel to conserve the oxygen. Oxygen Concentrator – This is an electrically powered device that separates the oxygen out of the air, concentrates it, and stores it. This system has a number of advantages because it doesn't have to be re-supplied and it is not as costly as liquid oxygen. Extra tubing permits the user to move around with minimal difficulty. Small, portable systems have been developed that afford even greater mobility. ^top What is Non-Invasive Ventilation? Noninvasive ventilation is the delivery of ventilatory support without the need for an invasive artificial airway. Such ventilation has a role in the management of acute or chronic respiratory failure in many patients and may have a role for some patients with heart failure. Noninvasive ventilation can often eliminate the need for intubation or tracheostomy and preserve normal swallowing, speech, and cough mechanisms. The use of noninvasive positive-pressure ventilation (NPPV) in acute hospital settings and at home has been steadily increasing. ^top C-PAP, stands for Continuous Positive Airway Pressure. Continuous means that the pressure delivered to the patient is the same for any given breath. C-PAP can actually increase the work of breathing and be lethal to an ALS patient As the use of Bi-PAP machines has increased, their cost has gone down. There are also more types of masks available and this has improved patient comfort and compliance. ^top Bi-PAP stands for Bilevel Positive Airway Pressure the use of Bi-PAP machines is often called non-invasive face mask ventilation. This is because the trachea is not incubated so there is less trauma to the airway and more importantly there is a lower incidence of nosocomial infections. ^top Bi-level means that the pressure
varies during each breath cycle. When the user inhales, the pressure
is similar to C-PAP. When they exhale, the pressure drops, making
it much easier to breath. Inhale, pressure rises, exhale, pressure
drops. Sometimes you will see a "ST" behind Bi-PAP, VPAP, or Bilevel. The ST stands for Spontaneous Timed. This means that if the user does not breath on their own, the machine will initiate a breath for them. This feature is very useful in treating central sleep apnea and a host of pulmonary disorders. ^top Masks attached to a patient's nose or mouth help supply positive pressure ventilatory support to the airways. CPAP can be supplied by attaching a mask to a conventional intensive care unit (ICU) ventilator or by using a simpler device designed solely for this purpose. This will raise functional residual capacity (which may reduce the inspiratory work to breathe in some disease states), and it can also be used to "splint open" collapsing/obstructed upper airways in disease states such as obstructive sleep apnea. BIPAP can also be supplied by attaching a mask to a conventional ICU ventilator and generally using a time cycled, pressure targeted mode (pressure assist control). The flow cycled, pressure targeted mode, pressure support, is not appropriate under these circumstances because mask leak may disrupt the ICU ventilator breath cycling algorithm. Simpler ventilators designed solely for mask application generally also supply pressure assist control. These devices often also provide pressure support by using special leak compensation mechanisms. BIPAP can not only accomplish the goals of CPAP noted above but can also further reduce inspiratory muscle loads through the application of additional inspiratory pressure. ^top If your doctor has told you that you have asthma, you probably have difficulty breathing and often cough or feel short of breath. Your doctor may hear wheezing when he or she listens to your chest with a stethoscope. Wheezing is a whistling sound that can be heard as you breathe. Irritants in the air cause your lungs to become inflamed and your airway to tighten, trapping air in your lungs. This produces an asthmatic episode or “attack.” ^top What are Allergic and Nonallergic Nasal Congestions? Allergic and non-allergic congestion is the uncomfortable feeling of being “stuffed up.” Allergic congestion is caused by allergies to food, chemicals or other substances, while non-allergic congestion is caused by a common cold or the flu. ^top Sinusitis is a bacterial infection of the sinus cavities. Sinus cavities are hollow air spaces in the skull that open into the nose for exchange of air and mucous. Infection of the sinuses interferes with normal sinus drainage and causes excess mucous production. Sinusitis can either be acute or chronic. ^top
Acute sinusitis frequently occurs after a common cold and lasts two to three weeks. If the symptoms occur three or more times per year or last longer than three weeks, it is considered chronic sinusitis. ^top Pulse oximetry is a simple non-invasive method of monitoring the percentage of haemoglobin (Hb) which is saturated with oxygen. The pulse oximeter consists of a probe attached to the patient's finger or ear lobe which is linked to a computerised unit. The unit displays the percentage of Hb saturated with oxygen together with an audible signal for each pulse beat, a calculated heart rate and in some models, a graphical display of the blood flow past the probe. Audible alarms which can be programmed by the user are provided. An oximeter detects hypoxia before the patient becomes clinically cyanosed. Pulse oximeters may be used in a variety of situations but are of particular value for monitoring oxygenation and pulse rates throughout anaesthesia. They are also widely used during the recovery phase. The oxygen saturation should always be above 95%. In patients with long standing respiratory disease or those with cyanotic congenital heart disease readings may be lower and reflect the severity of the underlying disease. In intensive care oximeters are used extensively during mechanical
ventilation and frequently detect problems with oxygenation before
they are noticed clinically. They are used as a guide for weaning
from ventilation and also to help assess whether a patient's oxygen
therapy is adequate. ^top
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