Long-term oxygen therapy

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As a long-term oxygen therapy ( Engl. Long-term oxygen therapy , short LOT or LTOT ) is in the medicine 's long-term and daily for several hours supply of oxygen called. It is used for diseases in which there is a severe chronic oxygen deficiency ( hypoxemia ) in the arterial blood . The survival time and quality of life of the affected patients can be improved by this treatment.

Causes of Oxygen Deficiency

The lack of oxygen can be caused by:

Consequences of a lack of oxygen

In severe hypoxemia, physical performance is severely limited. Even at low stress, patients complain of shortness of breath, weakness and rapid exhaustion. In addition to the reduced oxygen partial pressure (PaO 2 ) in the blood gas analysis , drumstick fingers with watch glass nails are often found . Fatal high pressure develops in the pulmonary arteries, which leads to a thickening of the blood vessel walls. As a result, the transport of oxygen from the air through the vascular membrane into the blood in the alveoli is additionally impaired: a vicious circle . Another consequence of pulmonary hypertension is an overload of the muscles of the right heart, which can lead to heart failure (right heart failure). In order to adapt to the lack of oxygen, the organism tries to produce more red blood cells , for example as it does during altitude training . However, this can lead to blood thickening with an increase in the hematocrit value ( polyglobulia ), which in turn has an unfavorable effect due to the deteriorated flow properties of the blood.

The reduced physical exercise capacity leads to muscle breakdown because of the permanent rest and thereby additionally restricts resilience in a further vicious circle.

indication

Before long-term oxygen therapy is used, the possibilities of drug treatment must be exhausted. In addition, the PaO 2 value in blood gas analysis must be in the critical range several times (below 55  mm Hg ≈ 7.3 kPa ) and must improve significantly when oxygen is added to the inhaled air. In the case of polyglobulia due to a lack of oxygen and pulmonary hypertension with or without overloading the right ventricle, long-term oxygen therapy is indicated even at PaO 2 values ​​below 60 mm Hg (7.9 kPa).

Another prerequisite for long-term oxygen therapy is that there is oxygenatory respiratory insufficiency (formerly partial insufficiency ). This means that the carbon dioxide (PCO 2 ) value in the blood should be below 45 mm Hg (5.9 kPa). If the PCO 2 value in the blood is higher than 44 mm Hg ( hypercapnia ), one speaks of ventilation insufficiency (previously global respiratory insufficiency ). Then sometimes even with PaO 2 values ​​below 70 mm HG (9.3 kPa), additional measures of assisted ventilation are necessary to relieve the strained respiratory muscles.

execution

Oxygen concentrator
Liquid oxygen tank with satellite
Patient with satellite and nasogastric tube

Long-term oxygen therapy is carried out on a long-term basis and should be used for at least 16 hours a day, including overnight. A short supply of oxygen, such as in emergency medicine or as an oxygen shower , cannot achieve the desired therapeutic success. The so-called oxygen multi-step therapy - an alternative medical procedure according to Manfred von Ardenne - is not a sufficient treatment given the above-mentioned conditions. In the case of long-term oxygen therapy, the statutory health insurance companies only cover the costs if there is a corresponding indication .

The oxygen is typically via a nasal cannula supplied (a non-sealed plastic nasogastric tube), wherein the amount is determined individually. The PaO 2 value should reach at least 65 mm Hg (8.7 kPa) with O 2 administration. In special cases, a catheter can be used for the O 2 supply , which is inserted from the outside through a puncture in the windpipe .

Oxygen systems

  • An oxygen concentrator , which can be operated from the domestic power supply, is a cheap way of supplying oxygen . The oxygen is physically sifted from the ambient air through a membrane filter . However, these heavy, wired devices are not suitable for patients who are still mobile. For these patients, however, there are now also small mobile battery-operated devices. However, because of their low power, these can only be pulsed, i. H. when inhaled, provide oxygen. The battery lasts for a few hours of operation before it needs to be recharged. Since around 2008 there have been mobile concentrators that can be operated with domestic electricity as well as with the help of vehicle electrics and also with built-in rechargeable batteries. If required, they can also be set to continuous flow, here the limit today (2013) is max. 3 liters of O 2 / min. With a weight of around 4–8 kg, they can also be used on the go. Most of them are also approved for use in aircraft.
  • Liquid oxygen systems contain deep-frozen (minus 183  ° C ) oxygen filled into thermally insulated tanks . They are particularly suitable for mobile patients and for those whose O 2 value deteriorates significantly under stress or who have an increased O 2 requirement (over 4 l / min). There are also smaller, portable devices ( satellites ) that allow oxygen to be supplied outside the home or when working. Their volume lasts about two to eight hours, depending on the amount of gas set. They can be refilled by the patient himself using the large tank (see illustration).
  • Pressurized gas cylinders , which are occasionally still prescribed, are not very suitable because of their weight and are also comparatively expensive, even if they are operated with oxygen-saving systems.
  • O-PUR disposable steel bottles and aerosol cans are extremely expensive and unsuitable for long-term therapy. If one liter per minute is required, an aerosol can lasts for two to eight minutes. A one-way steel bottle that lasts around two hours cost around 60 euros in 2008.
See also: oxygen cylinder

Therapeutic effect

The permanent administration of oxygen improves performance, and almost normal physical activity is sometimes possible. This avoids the breakdown of the muscles. The physical performance can be further increased through advanced training. Any increased pressure in the pulmonary artery can recede and thereby relieve the right ventricle again. If oxygen therapy is carried out consistently for more than 16 hours a day, the patient's life can be prolonged, combined with an improved quality of life.

Side effects

The undesirable effect of oxygen therapy is initially a drying out of the nasal mucous membrane , especially at flow rates over two liters per minute. An upstream humidifier must be carefully maintained as the water in it can be colonized by bacteria and fungi and then become a source of infection.

An oxygen toxicity of lung damage ( Lorrain-Smith effect ) is not to be feared in the amounts of oxygen that will be used in long-term therapy. Such effects can only occur at higher concentrations, for example when pure oxygen is supplied in closed systems over a longer period of time.

In patients with more elevated PaCO 2 values, i.e. those with ventilation insufficiency, with normalized PaO 2 values ​​there is initially the risk that the loss of the respiratory drive may lead to CO 2 anesthesia and respiratory arrest. However, a test phase when starting or changing the therapy protects against this.

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  1. ↑ B. Burrows, RH Earle: Course and prognosis of chronic obstructive lung disease. A prospective study of 200 patients. In: N Engl J Med . 280 (8), Feb 20, 1969, pp. 397-404. PMID 5763088
  2. ↑ JM Cranston: Domiciliary oxygen for chronic obstructive pulmonary disease. In: Cochrane Database Syst Rev. (4), Oct 19, 2005, p. CD00174
  3. ↑ AA Okubajedo, PW Jones, JA Wedzicha: Quality of life in patients with chronic obstructive pulmonary disease and severe hypoxaemia. In: Thorax. 51, 1996, pp. 44-47. PMID 8658368
  4. ^ Nocturnal Oxygen Therapy Trial Group: Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease: a clinical trial. In: Ann Intern Med . 93 (3), Sep 1980, pp. 391-398. PMID 6776858
  5. ↑ German Society for Pneumology: Recommendations for long-term oxygen therapy in severe chronic hypoxemia. In: Pneumology. 74, 1993, pp. 2-4.
  6. ^ P. Goldberg, H. Reissmann, F. Maltais, M. Ranieri, SB Gottfried: Efficacy of noninvasive CPAP in COPD with acute respiratory failure. In: Eur Respir J. 8 (11), Nov 1995, pp. 1894-1900. PMID 8620959
  7. ↑ MJ Kampelmacher, M. Deenstra, RG van Kesteren, CF Melissant, JM Douze, JW Lammers: Transtracheal oxygen therapy: an effective and safe alternative to nasal oxygen administration. In: Eur Respir J. 10 (4), Apr 1997, pp. 828-833. PMID 9150320
  8. ^ AO Harris-Eze, G. Sridhar, RE Clemens, TA Zintel, CG Gallagher, DD Marciniuk: Role of hypoxemia and pulmonary mechanics in exercise limitation in interstitial lung disease. In: Am J Respir Crit Care Med. 154 (4 Pt 1), Oct 1996, pp. 994-1001. PMID 8887597
  9. ↑ CK Cahill, J. Heath: Sterile water used for humidification in low-flow oxygen therapy: it is necessary? In: Am J Infect Control. 18 (1), Feb 1990, pp. 13-17. PMID 2156468

literature

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This version was added to the list of articles worth reading on May 21, 2006 .