Oxygen-Replacement Therapy:

Lung function may eventually worsen to the point that patients may need supplemental oxygen delivered through portable or stationary tanks.

Continuous Therapy. Continuous oxygen therapy (more than 15 hours a day) is the only treatment for emphysema that has been proven to prolong survival in certain patients. It also improves alertness, motor speed, and hand strength. Continuous oxygen therapy is usually recommended for patients with:

• Lung oxygen level below 55 mm Hg while resting
• Lung oxygen level below 60 mm Hg while resting, plus right heart failure or an abnormal increase in red blood cells

Ideally, the patient should receive enough oxygen to keep the oxygen level at 65 mm HG, but no less than 60 mm HG, or at an oxygen saturation level of at least 90%. Patients may need extra oxygen flow during sleep or physical activity.

About 40% of patients improve enough in 1 month to stop continuous treatment, although these patients should be observed closely. COPD often gets worse, and patients need to restart oxygen therapy. Some patients get worse in spite of treatment, although it is not possible to predict who is at risk for oxygen therapy failure. The addition of nitric oxide, a gas that widens blood vessels, may offer additional benefits.

Intermittent Oxygen. Patients with less severe COPD who are not on permanent oxygen maintenance may need supplemental oxygen during specific circumstances:

• Patients whose oxygen level drops below 55 mm HG only while exercising may benefit from supplemental oxygen during physical activity. Supplemental oxygen may improve endurance, and it enhances the delivery of oxygen to the muscles while they are working.
• Patients whose oxygen level drops below 55 mm HG during sleep may need oxygen at night. Such patients usually experience fitful, poor-quality sleep. This type of oxygen therapy does not appear to affect survival or prolong the time until patients need continuous oxygen therapy.

Oxygen During Travel. People on continuous oxygen therapy who are traveling by plane should increase their oxygen by 1 - 2 liters per minute during the trip. People on intermittent oxygen therapy may need oxygen during air travel for if the trip is longer than 2 hours and they develop symptoms, or if they experience a drop in oxygen levels before traveling. People are not allowed to bring their own oxygen tanks on board an airplane; many airlines will provide oxygen if notified 48 - 72 hours in advance. It is important to note that aircraft cabins are pressurized to the equivalent of 8,000 feet above sea level. Such pressures could be potentially dangerous for people with severe COPD.

Oxygen Storage and Delivery Systems

Unless they are bed-bound, patients usually use a combination of stationary and mobile oxygen systems.

Stationary Systems. The most common stationary oxygen system is the concentrator, an electrical device that pulls oxygen from the air. It weighs about 35 pounds and cannot be battery operated, so a patient can use only it at home.

Portable Units. Portable units containing electronic oxygen-conserving devices weigh only a few pounds and can provide up to 8 hours of oxygen. Some portable units weigh 6.5 lbs, with liquid oxygen supplies that last 4 hours. Some weigh 9.5 lbs, with an oxygen supply that lasts 8 hours when used at a flow rate of 2 liters per minute.

Compressed or Liquid Oxygen. Oxygen can be administered from large stationary tanks or small portable ones, either as compressed gas or liquid oxygen. A container of liquid oxygen lasts four times longer than compressed gas of the same weight, and it is easier to fill. Liquid oxygen is very beneficial for patients who want to maintain an active life, although the tanks require occasional venting to release pressure, and this wastes oxygen. They are also more expensive. In some areas, for example, a stationary liquid oxygen system costs $3,500 and a compressed oxygen tank costs $350.

Precautions. Supplemental oxygen is a fire hazard, and some hotels and residences do not allow its use. No one should smoke near an oxygen tank, and tanks should be stored safely, secured to a wall and away from heaters and furnaces.

Devices for Administering Oxygen

Oxygen is usually administered in one of three ways: through a nasal canula, transtracheal catheter, or electronic demand device.

Nasal Canula. Using a nasal canula, oxygen is delivered through a long, thin plastic tube that runs from the oxygen tank to small plastic prongs that fit in the nostrils. The tube can be very long when attached to a stationary tank in order to accommodate walking throughout a house, or relatively short when attached to a portable unit.

A reservoir pouch is a recent innovation added to this device that provides an extra rush of oxygen when a patient starts to inhale. This method is inexpensive and easy to use, but some patients are embarrassed by its appearance under their noses.

Transtracheal Oxygen. Transtracheal oxygen is delivered directly into the windpipe (trachea) through a catheter tube implanted by a surgeon. The device is inconspicuous, and patients are very likely to use it. The initial cost is high, but over time expenses drop because of more efficient oxygen usage. Long-term complications may include infection, dislodgment, and blockage by mucus, which can be very serious. Complications of the procedure itself occur in 3 - 5% of cases and can include lung spasms and uncontrollable coughing.

Electronic Demand Devices. Electronic devices that sense the beginning of a breath and deliver a pulse of oxygen are also available, although they are complicated, expensive, and have a risk for mechanical failure. Newer units have a continuous flow bypass switch that allows oxygen to still be delivered if the battery runs down.

Devices to Assist Breathing

In emergency situations, oxygen may be delivered to the patient in various ways:

Noninvasive Positive Pressure Ventilation (NPPV). If the patient is able to breathe naturally, oxygen is delivered through a tube using a tightly fitted oxygen mask to maintain airway pressure during breathing. Some physicians now believe such devices should be first-line treatments (in addition to medications) for managing respiratory failure after an acute exacerbation. NPPV allows the patient to talk and drink fluids, and is much easier to tolerate than nose or throat tubes. It cannot be used on patients with rapidly deteriorating COPD, those who are uncooperative, or those who have a facial shape that does not allow the mask to seal tightly.

Intubation. When standard oxygen therapy does not meet a patient's needs, endotracheal intubation may be required to deliver high concentrations of oxygen. With intubation, a tube is inserted down through either the nose or the mouth, and oxygen is given through the tube.

Mechanical Ventilation. In very serious cases such as acute respiratory failure, a mechanical ventilator can be used to take over the function of breathing. The primary goal of ventilation is to remove carbon dioxide and restore a balanced exchange of gases.

Most patients have a low tolerance for intubation, and the tubes are often removed early due to discomfort. Patients with these tubes may need painkillers, sedatives, or muscle relaxants.

There are also several complications that lead to the removal of breathing tubes:

• Bleeding
• Ejection of the tube after coughing
• Mucus plugs