Practice of Sleep Medicine by Boris A. Stuck & Joachim T. Maurer & Angelika A. Schlarb & Michael Schredl & Hans-Günter Weeß

Author:Boris A. Stuck & Joachim T. Maurer & Angelika A. Schlarb & Michael Schredl & Hans-Günter Weeß
Language: eng
Format: epub
ISBN: 9783030174125
Publisher: Springer International Publishing

4.6.3.2 Sleep-Related Hypoventilation and Hypoxemia Caused by Bronchial Obstruction

In Europe, about one third of all patients ventilated at home suffer from chronic obstructive pulmonary disease (COPD), which is frequently associated with emphysema. On average, the patients are of older age, and males are affected more frequently compared to other indications. In stable phases, the patients succeed rather well in maintaining respiration with maximum efforts of the respiratory muscles. Hypoxemia and hypercapnia are accepted.

However, oxygen administration via a nasal cannula that is used in many cases for improvement of the hypoxemia and that is rather comfortable for the patient is not sufficient to allow a relevant relief of the respiratory pump. In this way, low-grade additional efforts (e.g., in the context of an infection) lead to decompensation of the respiratory pump. Most frequently, the noninvasive ventilation is introduced for therapy of acute respiratory failure occurring in this context, which results in an intensive care hospitalization. For this indication, the benefit of noninvasive ventilation is proven. Under this aspect, a transition to a permanent nocturnal ventilation at home is expected to lead to a reduction of COPD exacerbations and as a consequence to reduced hospitalization rates.

If a nocturnal ventilation at home is started in the context of chronic respiratory failure based on stable COPD, the data situation is inconsistent regarding respiratory efforts, pressure of the pulmonary artery, blood gas alterations, structure of sleep, and physical capacity. Only the quality of life seems to improve. In particular, a decrease of the mortality rate in comparison to conservative therapy, however, could not be confirmed.

On one hand, this is not astonishing because ventilation therapy cannot reverse the causative lesion of the pulmonary parenchyma. However, on the other hand, short duration of use, a too low pressure peak, and a too short follow-up are criticized in the studies. At least, however, it seems that better clinical results may be achieved when severe hypercapnia is found preceding therapy and when the pressure difference between inspiration and expiration is set high, that is, to more than 18 mbar.

Furthermore, it has become obvious that the reduction of the CO2 partial pressure correlates with the daily duration of ventilation. Ventilation in the controlled mode may reduce diaphragmatic activity more significantly compared to the assisted mode, which may be interpreted as a more effective relief of the respiratory pump. Overall, the primary acceptance of ventilation at home amounts to about 80%; the daily duration of use is 6 h on average, which can be evaluated as extremely good.

In this context, a reluctant indication takes account of all this. In Germany, the following criteria are recommended for the introduction of noninvasive ventilation because of COPD: clear symptoms of chronic respiratory failure (see ► Sect. 4.1.4) and pathological blood gas values with either CO2 partial pressure over 55 mmHg during daytime or CO2 partial pressure of 50–54 mmHg during daytime and oxygen saturation below 88% for at least 5 min at night, despite the administration of 2 l/min of oxygen, or CO2 partial

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