Respiration; international review of thoracic diseases
-
Patients with neuromuscular disease may suffer from nocturnal respiratory failure despite normal daytime respiratory function. The physiological reduction in muscle tone during sleep may be life-threatening in a patient with impaired muscle strength. Nocturnal respiratory failure may occur in patients with the postpolio syndrome, amyotrophic lateral sclerosis, myasthenia gravis, myotonic dystrophy, and muscular dystrophy. ⋯ Daytime symptoms may include morning drowsiness, headaches and excessive daytime sleepiness. Polycythemia, hypertension, and signs of heart failure may also be seen. Effective treatment is available, and may improve the quality of life, and possibly increase survival.
-
Worsening of hypoxaemia during sleep in patients with chronic obstructive pulmonary disease has been extensively investigated in the past 20 years owing to the development of polysomnography and to the advent of reliable transcutaneous oximeters. Sleep-related hypoxaemia is characteristic of rapid-eye-movement (REM) sleep but may be present during other sleep stages. There is a strong relationship between nocturnal O2 saturation and the level of daytime PaO2: the more pronounced daytime hypoxaemia, the more severe nocturnal hypoxaemia. ⋯ The deleterious effects of sleep-related hypoxaemia include cardiac arrhythmias, 'hypoxaemic stress' on the coronary circulation and especially, peaks of pulmonary hypertension. The treatment of nocturnal hypoxaemia is conventional O2 therapy (both nighttime and daytime) in patients who exhibit marked daytime hypoxaemia (PaO2 < 55-60 mm Hg). At present data are not sufficient for justifying the use of isolated nocturnal O2 therapy in patients with nocturnal desaturation who do not qualify for conventional O2 therapy.
-
Review
Physical and functional properties of airway secretions in cystic fibrosis--therapeutic approaches.
The airway secretions which line the respiratory tract form a biphasic layer composed of an aqueous 'sol' layer and a more superficial 'gel' layer. In the sol layer, also described as the 'periciliary' layer or 'airway surface fluid', the cilia beat and relax. The lubricant sol layer enables the gel mucus present at the tips of the cilia to be transported by the ciliary beating of the ciliated cells. ⋯ In view of these alterations in the physical and functional properties of CF airway secretions, pharmacologic approaches should aim to rehydrate the mucus and to restore normal mucociliary or cough transport by stimulating chloride ion secretion (i.e. using UTP or ATP associated with amiloride in order to block sodium ion and water reabsorption). During acute episodes of infection, recombinant human DNase (rhDNase) may rapidly prevent mucus stasis by improving its rheologic properties. Lubrication of the mucus at the sol phase interface by 'surfactant' therapy may also represent a very promising therapeutic perspective to reduce the hyperviscosity and hyperadhesivity of airway secretions.
-
Respiratory failure is the leading cause of death in patients with amyotrophic lateral sclerosis (ALS). We review the physiology of respiratory compromise in ALS and techniques of monitoring respiratory function. Treatment options, including pharmacologic interventions, aspiration precautions, and invasive and noninvasive modes of mechanical ventilation are reviewed. ⋯ Four of 18 patients who elected to receive noninvasive ventilation decided to discontinue treatment. Four of 13 patients who were receiving mechanical ventilation elected to discontinue life support. The decision to utilize these modalities must be made with realistic considerations of the patient's quality of life.