Eur Respir J 1989, 2, 160-164

Report of a SEP (European Society of Pneumology) Task Group

Recommendations for long term oxygen therapy (LTOT)

This statement was. developed and modified in a meeting of the task group held on 7th S~ptem_ber 198~ 1n Bu~apes~. (VII Congress of Societas Europaea Pneumologica)

Cha1rman. P. Lev1 Valens1 (Am1ens, France) Members: P. Aubry (Amiens, France) C.F. Donne~ (Veruno, Italy}, D. Robert (Lyon, France}, K.H. Ruhle (Hagen, FRG},'

E. We1tzenblum (Strasbourg, France), R.Wurtemberger (Freiburg, FRG)

The aims of L TOT are the following: - Correction of hypoxaemia without inducing danger-

ous hypercapnic acidosis - Improvement of survival - Reduction of polycythaemia - Improvement of neuropsychological status - Improvement of sleep quality and prevention of

nocturnal hypoxaemic dips - Prevention of right heart failure - Improvement of quality of life - Reduction in health costs (frequency and days of

hospitalization)

Facts - some reminders

The MRC [1] and NOTT [2] studies are the only controlled investigations using L TOT in chronic ob­structive pulmonary disease patients (COPD). These studies have clearly demonstrated a significant survival difference between treated and untreated groups. The daily requirement of oxygen therapy has been stated to be at least 15 hours. Greater clinical benefit can be expected if the treatment is applied for at least 18 h per day. No randomized or controlled studies have been made in patients with disease other than COPD, in par­ticular restrictive lung disease (fibrosis, pneumoconiosis etc.) where LTOT is commonly used by some groups.

The effect of LTOT on haemodynamic parameters has been studied by TIMMS [3], WEITZENBLUM [4] and AsmrrosH [5, 6]. WEITZENBLUM [4, 7] demonstrated that LTOT can reverse the progression of pulmonary hyper­tension in COPD patients and TIMMS [3] using NOTT study observations, confirmed the value of continuous LTOT.

More recently, SLINGER [8] demonstrated the effect of removing oxygen in obstructive pulmonary disease. AsmrrosH [6] confirmed his first study [5] on haemo­dynamic effects of oxygen administration and its appli­cation to long term prognosis and suggested a non invasive test of responsiveness of pulmonary hyperten­sion to oxygen.

The group are grateful to P. Howard (Sheffield UK) for construc­tive criticsm and help in preparing the final version.

It is well known that hypoxaemia plays a different ~ale during the day from that during sleep, especially m blue and bloated patients with day time Pao <8kPa (60 mmHg) [9, 10]. The improvement of n~tumal hypoxaemia and its haemodynamic consequences have been reported by many authors [7, 11, 12, 13]. FLETCHER and LEVIN [14] who studied the acute and three week effects of oxygen breathing showed oxygen administration to prevent desaturation episodes and paroxysmal pulmonary hypertension. Recently, FLETCHER

[15] demonstrated that patients with day time Pao above 8 kPa (60 mmHg) can still have nocturnal hypoxaemia. The risk is higher for patients with day time Pao

2 between 8 and 8.7 kPa (60 and 65 mmHg)

who are on the steepest part of the oxyhaemoglobin dis­sociation curve. The mechanism of desaturation during sleep in COPD patients is related to two causes, REM sleep and the overlap syndrome [FENLEY 13, 16]. In the overlap syndrome, desaturations are either related to REM sleep or associated with obstructive sleep apnoea in non REM sleep. In some of these patients oxygen reduces desaturation but increases the number of sleep apnoea episodes.

The role of respiratory stimulants in the management of hypoxic patients is unclear. Almitrine improves Pao [17] but its effects on haemodynamic parameters ar~ controversial [18]. Different authors question the feasi­bility of combining LTOT with drugs [19, 20].

It is not therefore possible to standardize every aspect of LTOT and these difficulties have led to a wide variability in indications and operating conditions among prescribing Physicians.

In this short report we will deal with some of the recommendations for selection of patients, choice of oxygen supply and methods of administration.

Selection of patients

Selection of criteria

Pao2

is an important criterion for the selection of patients but an occasional single measurement of Pao is not a definitive indication for LTOT. Selectio~ criteria must include determination of a steady state [1, 2, 21, 22, 23], the use of suitable pharmacological

TASK GROUP REPORT 161

Table 1. - Choice of investigations before considering L TOT

Test Always nw.my

According to clinical circumstances and Pao2 levels

Clinical and radiological · Spirometry Daytime blood gas at rest Hb, Het Exercise testing Haemodynamics

Polysomnography (including EEG, EOG, EMG, Sao2,

airflow, rib cage and abdominal movements)

Hb: haemoglobin, Het: haematocrit

therapy (ATS guidelines, November, 1986), chest physiotherapy and preventive measures such as the stopping of tobacco. The need for a probationary pe­riod is clearly shown by follow up studies. Blood gas measurements in patients after an acute exacerbation Pao2<7.3kPa (55 mmHg), may improve even after dem­onstration of an apparent steady state [21, 22, 23, 24]. The circumstances are different after an acute exacer­bation than during long term management of COPD. For Pao2 levels between 6. 7 and 7 .3kPa (50 and 55 mmHg) a delay from one to three months is recomm­ended.

Methods of investigation

Investigations to be considered before LTOT are: clinical and radiological examination, blood gas measurement, haematocrit, exercise testing, haemody­namic investigation and sleep recording. Not all of these investigations are necessary in every case but should be chosen according to th.e clinical circumstances and Pao2 level (table 1).

Assessment of oxygen efficiency and tolerance: Oxygen tests

The patients should receive continuous LTOT and the dose should be sufficient to raise resting Pao2 to 8.7-10.7kPa (65-80 mmHg) by, selecting the most ap­propriate flow rate. In patients with hypoxaemic epi­sodes during sleep or exercise the flow selection tests should be made according to the clinical picture and the response to the administered 0 2 dosage reassessed pe­riodically (table 2).

Indications for L TOT

Indications usually admitted:

After a probationary period with chest physiotherapy, stopping tobacco and drug treatment steady state COPD

+ + + + + Pao

2 7.3- 8.7kPa (55-65 mmHg)

Pao ;?: 7.3kPa (55 mmHg) dur­ing The day with polycythaemia, sleep desaturation or exercise desaturation (when possible)

Pao2

7.4-8.7kPa (56-65 mmHg) wit.li polycythaemia or chronic cor pulmonale. Snoring obese COPD patients (when possible)

patients with Pao2<7.3kPa (55 mmHg) according to MRC and NOTI criteria.

Questionable indications

a) Currently accepted - COPD with Pao2 7.3-8.7kPa (55--65 mmHg) with:

- polycythaemia or - clinical evidence of cor pulmonale or - pulmonary hypertension

In this group of patients other investigations are necessary: haemodynamics, sleep recording, exercise testing

Controversial

b) Restrictive lung disease (interstitial pulmonary fibro­sis, pneumoconiosis) with Pao2<7.3k.Pa (55 mmHg)

Choice of 0 2 supply

The choice of source depends on the duration of utili­sation, the oxygen flow rate required, the possibility of ambulatory use, the geographical area of residence and the patient's interest in both physical and social activi­ties (table 3).

Methods of administration

Conventional methods

Nasal prongs. This method is simple and inexpensive and the most commonly used delivery system for 0 2 at flow rates up to 4 l·min·1•

The continuous 0 2 flow is usually related to the in­stantaneous inspiratory flow, consequently the tracheal F10

2 varies during the inspiratory phase.

Under a flow rate of 3 l·min·1 this method is usually

162 P. LEVI V ALENSI

Table 2. - Oxygen tests

Test available

Blood gases at rest, breathing room air and oxygen Determination of flow rate

Sleep recording during room air and oxygen breathing Sao2, Ptcco2 or blood gases by arterial puncture 4 h after the onset of sleep, as quickly as possible with apnoea detection

Tolerance and efficacy

Exercise, 12 min walking test (McGavin) with determination of 0 2 flow rate and carrying capacity

Exercise test in steady state

Haemodynamics and/or Vo2

symptom limi­ted to distinguish responders and indicate prognosis. ~PAP> 5 mmHg Vo

2 <6.5 ml·min-1-Kg-1

(New selection criteria suggested by AsHUTOSH) [6]

well tolerated and the gas does not require humidifica­tion. Higher flows may be uncomfortable due to dry­ness of the nasal mucosa and may be responsible for local irritation and sometimes bleeding.

Aesthetic qualities are poor. Efficacy is disrupted either when prongs are displaced (during sleep) or dur­ing oral breathing (exercising, speaking, sleeping).

Naso-pharyngeal chatheters. These devices may im­prove the efficiency of oxygenation in case of oral breathing but are seldom used at home. Oxygen humidi­fication and periodic changes are necessary and aes­thetic appearance is poor.

Simple masks. They are seldom used at home. The dead space of the mask may increase Paco2 and require higher 0 2 flow rates (above 5 l·min-1) . They do not per­mit eating or speaking, are usually not well tolerated and appearance is obstrusive.

Non conventional methods

Trans-tracheal catheter. Trans-tracheal oxygen therapy was first proposed by HEMUcH in 1982 [25]. Since that time more than 3,000 patients have been treated. The principle of the method is to deliver 0 2 into the tra­chea 2 cm above the carina through a small catheter (1 to 2 mm of internal diameter) inserted percutaneously at the level of the first tracheal ring.

Always necessary

+

+?

According to clinical diagnosis and Pao

2 level

Snoring obese patients, Pao2>8.7kPa (65 mmHg), morning headache

Patients who develop hypox­aemia during exercise

Pao2 7.3-f>.7 kPa (55-65 mmHg)

Trans-tracheal catheters have a number of advantages: The reduction of the 0 2 flow by approximately 50% compared with the conventional nasal route.

Oxygenation does not vary with the pattern of breath­ing

Enables 24 h·day of use and consequently maximum efficacy is obtained at all times

A major advantage is the cosmetic quality of the method since the catheter insert at the level of the neck can be totally concealed

Conversely the method has some disadvantages: - it is invasive, needing a procedure to insert the cathe­ter into the trachea (30 min), - requires close supervision during the first weeks and education of the patient to enable him to take care of his own treatment, and - a big problem and sometimes a real hazard, is the fonnation of mucous balls made of dried secretions attached to the catheter. They may decrease the effi­ciency of oxygenation or hinder ventilatory flow.

They are suitable for patients requiring high 0 2 flow rates (>3 1-min-1) or for the very anxious who wish to appear as normal as possible without 0 2 lines on the face.

Oxymiser. This device uses a small reservoir (20 ml) inserted in the 0 2 line which fills with pure 0 2 dur­ing the expiratory period to be inhaled at the very beginning of the following inspiration [23, 26]. Tbe

TASK GROUP REPORT

Table 3. - Choice of criteria for supply source of LTOT

Supply source

Gaseous oxygen

Fixed cylinders

Portable cylinders

Liquid oxygen

Fixed system

Portable system

Oxygen concentrators

Advantages

Tried and tested system Operating delivery circuits

Operating delivery circuits

May be used in conjunction with a concentrator

Useful in rehabilitation programmes

Great reserve supply Refilling less frequent

Reserve supply greater than gaseous source Useful in rehabilitation programmes

No delivery circuits The least onerous solution

Disadvantages

Fixed supply Frequent replacements or large storage area

Refilling difficulties (changing manometers) Limited period of use

Possible psychological reticence in outside use

Evaporation losses Necessity to organise delivery circuits Necessity to treat at least 20 patients to minimise costs

The same for fixed system Possible psychological reticence in outside use

Fixed installation or only partially mobile No possibility of use for physical activity Needs regular maintenance using technical assistance Not useful in rehabilitation programmes

Preferential indication for use

Technique used less and less Possible renewal of interest with oxygen conserving device

Patients with a limited

l63

capability of perambulation Complementary use with concentrator

Patients unable to leave home

Patients with reasonable possibility of perambulation Rehabilitation programmes When patient is strongly motivated towards his treatment and his normal social life

Patients unable to leave home Oxygen therapy 15-18 h maximum Unfavourable geographical areas (difficult access mountain regions etc)

reservoir may be positioned either under the nose like a moustache or in a pendant at the level of the thorax. 0 2 is delivered with nasal prongs. This system may save from 30% to 50% of the 0 2 supply dependent on the flow rate. Used during ambulation the portable 0 2 source may last longer. ARLA11 [27] demonstrated that reservoir nasal prongs improve protection against desaturation during exercise in COPD.

- Exercise hypoxaemia with day time normoxia

Pulsed demand valve. The principle is to deliver 0 2 only at the beginning of the inspiratory phase avoiding 0

2 wastage. The valve is triggered either by tempera­

ture or more recently by the negative pressure of early inspiration [18]. Oxygen savings may reach more than 50%. A demand valve may be incorporated in all sup­ply sources. It may be used either in a sedentary posi­tion or during ambulation [22].

The future. We need further investigations into the following fields: - Sleep related disorders causing hypoxaemia but with­

out day time hypoxaemia

- Patients with fibrosis and pneumoconiosis

References

1. MRC Working Party. - Long-term domiciliary oxy­gen therapy in chronic hypoxic cor pulmonale complicat­ing chronic bronchitis and emphysema. Lancet, 1981, 1, 681-186. 2. Nocturnal oxygen therapy trial group. - Continuous or nocturnal oxygen therapy in hypoxemic chrof!ic obstructive lung disease. A clinical trial. Ann Intern Med, 1980, 93, 391-398. 3. Timms RM, Khaja FU, Williams GW. - Hemodynamic response to oxygen therapy in chronic pulmonary disease. Ann Intern Med, 1985, 102, 29-36. 4. Weitzenblum E, Sautejeau A, Ehrahrt M, Mammosser M, Pelletier A.·- Long-term oxygen therapy can reverse the pro­gression of pulmonary hypertension in patients with chronic obstructive pulmonary disease. Am Rev Respir Dis, 1985, 131, 493-498. 5. Asthutosh K, Mean G, Dunsky M. - Early effects of oxygen administration and prognosis in chronic obstructive

164 P. LEVI VALENSI

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