What is Long-Term Oxygen Therapy (LTOT)?

Long-Term Oxygen Therapy (LTOT)

Long-Term Oxygen Therapy (LTOT) is a treatment that provides supplemental oxygen for at least 15 hours per day to patients with chronic hypoxemia, primarily to improve survival and quality of life in those with resting PaO2 ≤7.3 kPa (55 mmHg) or ≤8 kPa (60 mmHg) with specific complications. 1

Definition and Purpose

LTOT refers to the provision of supplemental oxygen for continuous use at home for patients with chronic hypoxemia. The primary goals of LTOT are to:

• Improve survival
• Improve pulmonary hemodynamics
• Enhance quality of life
• Prevent complications associated with chronic hypoxemia

Indications for LTOT

COPD Patients (Strongest Evidence)

• Patients with stable COPD and resting PaO2 ≤7.3 kPa (55 mmHg) 1
• Patients with stable COPD with resting PaO2 ≤8 kPa (60 mmHg) with evidence of:
  • Peripheral edema
  • Polycythemia (hematocrit ≥55%)
  • Pulmonary hypertension 1
• Patients with resting hypercapnia who fulfill other criteria for LTOT 1

Other Conditions (Evidence Extrapolated from COPD Studies)

LTOT is indicated in the following conditions using the same criteria as for COPD:

1. Interstitial Lung Disease (ILD):

   • Resting PaO2 ≤7.3 kPa
   • Resting PaO2 ≤8 kPa with peripheral edema, polycythemia, or pulmonary hypertension 1

2. Cystic Fibrosis (CF):

   • Resting PaO2 ≤7.3 kPa
   • Resting PaO2 ≤8 kPa with peripheral edema, polycythemia, or pulmonary hypertension 1

3. Pulmonary Hypertension:

   • PaO2 ≤8 kPa 1

4. Advanced Cardiac Failure:

   • Resting PaO2 ≤7.3 kPa
   • Resting PaO2 ≤8 kPa with peripheral edema, polycythemia, or pulmonary hypertension 1

5. Neuromuscular or Chest Wall Disorders:

   • NIV is first-line treatment for type 2 respiratory failure
   • LTOT may be added if hypoxemia persists despite NIV 1

Assessment and Prescription Requirements

Patient Selection

• Patients should be clinically stable (at least 8 weeks after last exacerbation) 1
• Patients with resting SpO2 ≤92% should be referred for blood gas assessment 1
• Patients with clinical evidence of complications (peripheral edema, polycythemia, pulmonary hypertension) may be considered for assessment at SpO2 levels ≤94% 1

Duration of Use

• LTOT should be used for at least 15 hours per day to achieve survival benefits 1, 2
• Optimal use is considered to be 24 hours per day, with breaks as needed for practical reasons

Special Considerations

Smoking

• If LTOT is prescribed for patients who continue to smoke, they should be informed that clinical benefits may be limited 1
• Smoking while using oxygen presents significant safety risks

Equipment Options

Three main types of portable oxygen equipment are available:

• Portable gas tanks
• Portable liquid tanks
• Portable oxygen concentrators (POCs)

Each has limitations that can affect patient mobility and daily activities, with POCs being the most common and least burdensome, though 29% of users still report high associated burden 3

Clinical Pitfalls to Avoid

1. Premature Assessment: Assessing patients during or immediately after an exacerbation can lead to unnecessary LTOT prescription. Wait at least 8 weeks after an exacerbation for proper assessment 1

2. Inadequate Duration: Prescribing LTOT for less than 15 hours per day may not provide survival benefits 2

3. Inappropriate Indications: Prescribing LTOT for patients with moderate hypoxemia (PaO2 between 55-65 mmHg) without other criteria has no proven benefit 2, 4

4. Neglecting Reassessment: Patients' oxygen needs may change over time, requiring periodic reassessment

5. Overlooking Equipment Limitations: Different oxygen delivery systems have specific advantages and limitations that should be matched to patient needs and lifestyle 3

LTOT represents a significant advancement in the management of chronic respiratory failure, offering proven survival benefits when properly prescribed and used according to established guidelines.