Oxygen therapy can improve the oxygen supply to hypoxic tissues and ensure the cellular metabolism. While hyperbaric oxygen therapy and acute oxygen therapy are mostly done in hospitals, in recent years, more and more patients are receiving home oxygen therapy, and oxygen cylinders and oxygen concentrators are commonly used in patients' homes. It is important to note that excessive administration of oxygen is harmful, and the danger of hyperoxia is also known as "oxygen toxicity". Oxygen therapy is a medical practice and, like medication, requires medical advice and adherence to treatment protocols.
I . What conditions require home oxygen therapy?
1.Chronic lung disease: for example, patients with chronic obstructive pulmonary disease (COPD), interstitial lung disease, pulmonary cystic fibrosis, pulmonary hypertension.
2.Chronic heart failure: especially patients with progressive or end-stage heart failure.
3.Neuromuscular and chest wall diseases: patients who develop respiratory failure and cannot correct hypoxia despite non-invasive ventilator therapy.
4.Patients with cancer or end-stage cardiopulmonary disease who have intractable dyspnea.
5.Patients with individual chronic diseases without hypoxia at rest, but with wheezing and hypoxia during activity.
Q: What is severe hypoxemia?
A: Severe hypoxemia is defined as: arterial partial pressure of oxygen ≤ 55 mmHg (pulse oximetry ≤ 88%) when inhaling room air at standard atmospheric pressure; or moderate hypoxemia with swollen limbs, increased red blood cells (erythrocyte pressure product ≥ 55%) or pulmonary hypertension.
Moderate hypoxemia is defined as: arterial partial pressure of oxygen = 56-59 mmHg (pulse oximetry in the range of 89%-93%) when inhaling room air at standard atmospheric pressure.
- Oxygen therapy is only suitable for hypoxic patients and cannot solve the treatment problem of non-hypoxic dyspnea;
- ② Long-term oxygen therapy is generally not recommended in the absence of hypoxia or only mild hypoxia (pulse oximetry >93%);
- ③ The criteria for determining hypoxemia is based on the arterial partial pressure of oxygen in the "blood gas analysis" test, and the pulse oximeter There are many factors affecting the determination of pulse oximetry, and it is for clinical reference only.
II . The precautions of home oxygen therapy
- Ensure the safety of oxygen
Oxygen is a safe, non-combustible gas, but it can fuel combustion, and some materials are very easy to catch fire and burn under the condition of oxygen. Home oxygen therapy should be kept away from heat sources and open flames (at least 10 meters), smoking is strictly forbidden, be cautious of using gas and heating appliances at the same time; avoid using or placing alcohol-containing items (such as air freshener, hairspray) near the oxygen device; turn off the oxygen in time when stopping oxygen intake; install smoke detectors and spare fire extinguishers at home in case of fire and other emergencies.
- Pay attention to adverse reactions
Adverse reactions of oxygen therapy mainly include dryness or bleeding of the nasal mucosa, skin pressure or irritation around the mask or nasal cannula, aspiration pulmonary atelectasis, hypercapnia and respiratory depression, oxygen toxicity, etc.
III . What are the ways of home oxygen therapy
Long-term oxygen therapy (LTOT)
For patients with chronic cardiopulmonary disease who develop severe hypoxemia, oxygen therapy for at least 15 hours per day. Start with an oxygen flow rate of 1 L/min and increase until the patient's pulse oxygen saturation is >90%, at which point a blood gas analysis may be considered to confirm that the goal of an arterial partial pressure of oxygen at rest ≥ 60 mmHg is achieved.
Ambulatory oxygen therapy (AOT)
For patients who do not have hypoxia at rest but develop hypoxia during exercise, a portable oxygen device is used to supplement oxygen during the patient's exercise and daily activities.
Nocturnal Oxygen Therapy (NOT)
Oxygen is supplied only at night, not during the day, for patients who develop hypoxemia during sleep. Patients with respiratory failure present should be considered for non-invasive ventilator therapy at the same time.
Palliative oxygen therapy (POT)
Indicated for patients with advanced cancer or end-stage cardiopulmonary disease, using oxygen to relieve intractable dyspnea.
Short pulse oxygen therapy (SBOT)
Refers to a short period of intermittent oxygen therapy (usually 10-20 minutes) administered before and after exercise.
VI. What devices are available for home oxygen therapy?
Oxygen supply equipment
The common sources of oxygen for home oxygen therapy are medical oxygen cylinders, oxygen concentrators and liquid oxygen systems, which are divided into fixed and portable types according to whether they can be carried around or not.
① Medical oxygen cylinders: store compressed medical oxygen, with a pressure valve and flow meter connected to the cylinder to observe the remaining air volume and adjust the oxygen flow. Home oxygen therapy most often uses 10-liter oxygen cylinders, while 1-liter and 4-liter oxygen cylinders are often portable.
② Oxygen concentrators: most of them are oxygen concentrators, 1) filtration: through zeolite molecular sieve, variable pressure adsorption technology and other physical methods, filtering the air inhaled by the oxygen concentrator dust, bacteria and other particles. 2) concentration: the oxygen concentrator forces the air into the cylinder containing "molecular sieve" or "semi-permeable membrane The cylinder contains "molecular sieve" or "semi-permeable membrane" material, in which nitrogen is absorbed, leaving the oxygen concentrated and purified, and finally medical grade oxygen is delivered to the patient through a continuous or pulsed dose delivery system.
The output of the oxygen concentrator is usually measured in "l/min". Low-flow oxygen concentrators can deliver 0.5-5 l/min of oxygen; high-flow oxygen concentrators can deliver 10-15 l/min of oxygen. Oxygen concentrators can also be divided into fixed and portable, and portable oxygen concentrators are powered by built-in rechargeable batteries.
There are low-flow systems and high-flow systems. Home oxygen therapy mostly uses low-flow oxygen delivery systems, including nasal cannula, simple mask, non-repetitive breathing mask, etc.
① Nasal catheter: the most commonly used, generally set 1-6 l/min oxygen flow (oxygen concentration 25-45%), if the oxygen flow > 6 l/min, the high speed oxygen flow is very shocking to the nasal mucosa, it is recommended to use a simple mask to absorb oxygen instead. Nasal catheter oxygen, can talk and eat at the same time, but it is easy to shift, especially for patients with deviated nasal septum or nasal polyps with poor effect, then it is recommended to choose nasal plug or nasal cannula.
② Simple mask: generally set 5-10 l/min oxygen flow, oxygen is supplied through the small-diameter tube at the bottom of the mask, and carbon dioxide is exhaled through the side holes on both sides of the mask. Room air also enters the mask through the side holes and mixes with oxygen, so an oxygen flow rate of >5 l/min is required to prevent carbon dioxide re-inhalation. Oxygenation by mask may restrict the patient from eating and drinking, and may even be claustrophobic.
③ Non-repetitive breathing mask: The one-way valve between the mask and the storage bag prevents exhaled air from entering, and the storage bag can deliver high concentration of oxygen, usually set at 10-15 l/min (80-95% inhalation concentration), if the oxygen flow rate is <10 l/min, the storage bag will collapse during inhalation. It is suitable for patients with severe hypoxia who are breathing well, but if the patient vomits, there is a risk of carbon dioxide retention and misaspiration.
Above: Nasal cannula (left), simple mask (middle), and non-rebreathing mask (right).
V. How to maintain oxygen therapy equipment?
1.It is recommended to clean the nasal cannula or mask once a day, wash and air-dry it for use, and replace one set every 2-4 weeks; frequent cleaning is required during illness, and timely replacement to prevent cross infection.
2.It is recommended to clean the humidifier bottle once every 3 days, wash and air-dry it and refill it with distilled water.
3.It is recommended that once a month to clean or replace the air filter, soak disinfection, rinse under running water and dry for use.
4.It is recommended to replace the gas pipe once every 2 months, the surface of the machine can be wiped with a clean, slightly damp soft cloth, and the equipment and its supporting devices are regularly maintained every year.
5.Oxygen therapy room to maintain air circulation, oxygen cylinders to use to stand, oxygen machine should be placed in a stable ground, and pay attention to fire, heat, dust, moisture.