Lot

In a preliminary pilot study conducted in 1967, Levine and colleagues found that oxygen therapy improved pulmonary hypertension in patients with COPD or hypoxemia (Koczulla 2018).

The first large-scale study of long-term oxygen therapy (LTOT) in COPD patients was published in 1981 as the MRC study and demonstrated significant benefits in terms of quality of life and mortality compared to patients not receiving LTOT (Triche 2025).

LOT (long-term oxygen therapy) refers to the administration of oxygen for ≥ 15 hours per day to improve quality of life and reduce mortality in patients with chronic hypoxemia (2020 Guidelines), for which treatment is indicated for longer than 3 months (Matthys 2008).

When administering oxygen long-term, it is first necessary to determine whether the condition is:

• hypoxemic respiratory failure, also known as Type I (2020 Guidelines), or
• hypercapnic respiratory failure, referred to as Type II (2020 Guidelines)

Type I:

In Type I, pO₂ is decreased, but pCO₂ is not elevated (Herold 2025). Examples of Type I conditions include

• diffusion disorders such as:
  • Idiopathic pulmonary fibrosis
  • Advanced sarcoidosis
  • Asbestosis
  • Silicosis
• Ventilation-perfusion distribution disorders, such as:
  • Pulmonary emphysema
  • Chronic obstructive pulmonary disease
• Chronic pulmonary vascular diseases, such as:
  • Chronic thromboembolic pulmonary hypertension
  • Pulmonary arterial hypertension
• Following major lung surgery, such as:
  • Pneumonectomy
  • Lobectomy (KI)

Patients are cyanotic and exhibit hypoxemia. Oxygen can be administered without difficulty in Type I (Herold 2025).

Type II:

In Type II, however, in addition to a decreased pO₂, there is also an elevated pCO₂ (Herold 2025).

Examples of Type II conditions include:

• Obstructive airway diseases such as:
  • Severe COPD
  • Cystic fibrosis
• Restrictive thoracic disorders, such as:
  • Post-thoracic reconstruction
  • Severe kyphoscoliosis
• Neuromuscular disorders, such as:
  • History of polio
  • History of paraplegia
  • Duchenne muscular dystrophy
  • Amyotrophic lateral sclerosis
• Obesity-hypoventilation syndrome, such as:
  • Pickwick syndrome (KI)

In Type II, oxygen administration requires closer monitoring of the patient, as hypercapnia may occur during O₂ administration. If necessary, noninvasive ventilation (NIV) should be initiated (Herold 2025).

Testing:

To prescribe a LOT, patients with a PaO₂ < 55 mmHg or, in cases of cor pulmonale, ≤ 60 mmHg are first tested without oxygen, then with oxygen at rest, during exercise, and at night.

The flow rate in liters per minute that results in an increase in oxygen pressure to at least 60 mmHg at rest and during exercise is prescribed. In advanced stages of the underlying disease, an increase in oxygen pressure of at least 10 mmHg is also sufficient (Herold 2025).

Indications:

The indication for LOT should be evaluated if, during a stable phase of the disease, pulse oximetry saturation at rest is ≤ 92% (Guideline 2020).

LOT is indicated for:

• PaO₂ ≤ 55 mmHg
• PaO₂ > 55 mmHg and ≤ 60 mmHg, if the following conditions are also present:
  • Secondary polycythemia with hematocrit levels ≥ 55%
  • Cor pulmonale with or without right heart failure
• If chronic hypoxemia is still present after all other therapeutic measures have been exhausted
• In palliative care
  • in addition to oxygen therapy during physical exertion (AOT)
  • and short-term oxygen administration (SBOT) (2020 Guideline)

Prescribing LOT for patients who smoke is subject to additional considerations (2020 Guideline). They should be informed—preferably in writing—about the risk of explosion and fire (Triche 2025).

Systems for LOT:

• Stationary oxygen concentrators
• portable oxygen concentrators
• Pressurized oxygen cylinders
• Liquid oxygen
• Devices for high-flow nasal oxygen therapy (2020 guidelines)

The preferred method of administration is nasal prongs (2020 Guidelines).

Liquid oxygen systems are suitable for mobile use; gaseous oxygen is generally used only in emergencies (Herold 2025).

Breath-triggered demand devices reduce the devices’ O₂ consumption (Herold 2025).

Contraindications:

In cases of respiratory failure, respiratory-depressant medications such as morphine, barbiturates, and diazepam are contraindicated. An exception is made for patients in the terminal stage of a pulmonary disease, as the administration of morphine for dyspnea may be appropriate in these cases for palliative reasons (Herold 2025).

Effects:

• Improved quality of life
• Prolongation of survival (Herold 2025)
• Increased physical endurance (Pforte 2002)
• In male patients, the positive effect on mortality is less pronounced than in female patients (Matthys 2008).
• Patient education:
  • Patients must first be trained in LOT (Guidelines 2020).

Adverse side effects:

Significant increase in CO2 levels, known as hypercapnia, which can lead to apnea (Herold 2025)

Regular follow-up visits should be scheduled as part of a LOT. For standard treatment initiation, the first follow-up visit should take place after 3 months; subsequent visits should be scheduled based on the patient’s clinical condition and adherence to therapy (Triche 2025).

A portable oxygen supply is available for air travel; a request for this must be submitted to the airline at least 48 hours before the trip (2020 Guidelines).

1. Herold G et al. (2025) Internal Medicine. Herold Verlag 337–338, 412
2. Kasper D L, Fauci A S, Hauser S L, Longo D L, Jameson J L, Loscalzo J et al. (2015) Harrison’s Principles of Internal Medicine. McGraw-Hill Education
3. Koczulla A. R., Schneeberger T., Jarosch I., Kenn K., Glöckl R. (2018) Long-Term Oxygen Therapy. Dtsch Arztebl Int 871–877
4. Guideline (2020) Guideline on Long-Term Oxygen Therapy. AWMF No. 020-002 https://register.awmf.org/assets/guidelines/020-002l_S2k_Langzeit_Sauerstofftherapie_2025-07-abgelaufen.pdf
5. Matthys H, Seeger W (2008) Clinical Pulmonology. Springer Medizin-Verlag Heidelberg 225–226
6. Pforte A (2002) COPD—Chronic Obstructive Pulmonary Disease and Complications. Blackwell-Wissenschaftsverlag, Berlin/Vienna, p. 206
7. Triche D (2025) Long-Term Oxygen Therapy. CME Continuing Education https://www.cme-kurs.de/kurse/langzeitsauerstofftherapie