Oxygen therapy, also known as supplemental oxygen, is the use of oxygen as a medical
treatment This can include for low blood oxygen, carbon monoxide toxicity,
cluster headaches, and to maintain enough oxygen while inhaled anesthetics are
given. Long term oxygen is often useful in people with chronically low oxygen
such as from severe COPD or cystic fibrosis. Oxygen can be given in a
number of ways including nasal cannula, face mask, and inside a hyperbaric
chamber.
Oxygen is required for normal cell metabolism. Excessively high concentrations can cause oxygen toxicity such as lung damage or result in respiratory failure in those who are predisposed. Higher oxygen concentrations also increase the risk of fires, particularly while smoking, and without humidification can also dry out the nose. The target oxygen saturation recommended depends on the condition being treated. In most conditions a saturation of 94-96% is recommended, while in those at risk of carbon dioxide retention saturations of 88-92% are preferred, and in those with carbon monoxide toxicity or cardiac arrest they should be as high as possible.The most advanced and severe stages of COPD are often accompanied by respiratory failure characterized by arterial hypoxemia which, if left untreated, leads to a reduction in survival when it reaches values below 55-60 mmHg. Patients who fail to meet their oxygen needs through breathing continuously need supplemental support, particularly under strain (walking, gymnastics), since the body can not store oxygen.
Long-term oxygen therapy increases life expectancy, decreases
dyspnoea, improves efficiency and quality of life, and supports the
cardiovascular system. The therapy is really effective only if the oxygen supply
is assured for at least 16 hours a day. The ideal would be a 24-hour supply. To
make a diagnosis, the doctor places the patient in brief observation without the
aid of oxygen therapy and then performs the analytical hemogas survey.
In these cases it is necessary to establish an oxygen treatment continuously,
for at least 15 hours (1), better for 18-24 hours a day, and long-term (LTOT).
The hours of treatment obviously include nighttime hours preferably with low
oxygen flows (generally from 1 to 2 liters / min). The flow must be adequate to
maintain the PaO2> 60 mmHg and the oxygen saturation (S02%)> 92%. In hypercapnic
patients, the administration of low-flow oxygen is recommended to prevent
dangerous increases in C02 with episodes of decompensated respiratory acidosis.
The indications to the LTOT, according to the various national and international
guidelines. The LTOT is indicated in patients who are stable, at rest and with
the best possible treatment, in blood gas tests repeated over time at least
fifteen days apart. on the other hand and for a period of at least two
consecutive months, present:
- Pa02 <55 mmHg or
- Pa02 between 56 and 59 mmHg, in the presence of pulmonary arterial
hypertension, pulmonary edema, declivity, hematocrit> 55%. The efficacy of the
chosen oxygen flow and the persistence of the indication to the LTOT must be
verified periodically at 3 months and 12 months after the introduction in LTOT
and periodically at least once a year or at each change of the clinical status
of the patient.
The prescription of OTLT is highly specialized and presupposes some criteria, that is, that in the absence of oxygen therapy the partial pressure of oxygen in the blood decreases below the following values:
- Pa02 <55 mmHg
or
-Pa02 between 56 and 59 mmHg, in the presence of pulmonary arterial hypertension,
pulmonary heart, declining edemas, hematocrit> 55%.
It is also true that
the use of oxygen, especially with nasal cannulae, can be highly dangerous in
patients who present with a base bad blood gas analysis with high values of CO2
(hypercapnia). In these patients the use of oxygen therapy with Venturi-type
masks with an appropriate percentage (28% or 35%) is indicated. Rather, the use
of a B-level ventilator is recommended in the most severe cases.
People with COPD and chronic respiratory failure who experience frequent
exacerbations and who need repeated hospital admissions have hypercapnia can
benefit from non-invasive chronic ventilatory treatment (NIV), after appropriate
specialist assessment. In order to improve pulmonary function, in selected
patients, it is also possible to resort to surgical techniques such as
bullectomy, ie the removal of pulmonary bubbles, and to the reduction of lung
volume, which can be obtained through the surgical ablation of the pulmonary
zones. apicals affected by the emphysematous process, or by the introduction,
within the bronchi, of unidirectional valves aimed at desufflating the
emphysematous parenchyma or with other bronchoscopic techniques still in the
validation phase. These methods of bronchoscopic treatment are to be reserved
for carefully selected patients and to be implemented in centers with proven
experience in the sector. In the case in which the patient suffering from COPD
presents a severe functional reduction and a marked clinical impairment,
characterized by a FEV1 <20% value, need for long-term oxygen therapy and
repeated hospitalizations for exacerbation of the basic pathological condition,
may be a candidate at pulmonary transplantation. Lung transplantation has a
favorable impact on respiratory function, exercise capacity and quality of life,
while its survival effect remains controversial.