[From vibration trauma to pharyngeal muscle instability: A self-sustaining pathophysiological process (circulus vitiosus) in obstructive sleep apnea].

Pharyngeal stability is ensured by both anatomical and non-anatomical factors. In addition to the anatomical width, functional factors are also significant in determining the degree of obstruction of the upper airway. The functionality of the pharyngeal muscles depends on an undisturbed sensorimotor system.

[Critical Closing Pressure (Pcrit) and Negative (Subatmospheric) Expiratory Pressure (NEP) for Diagnosis of Pharyngeal Collapsibility in Patients With Obstructive Sleep Apnea (OSA)].

The determination of critical closing pressure (Pcrit) is the diagnostic gold standard for assessing the severity of pharyngeal instability. Pcrit measurements are typically performed during natural nocturnal sleep (NREM Stage 2) in combination with polysomnography. However, determining Pcrit during sleep is time-consuming and impractical for routine use.

[Valsalva and Müller maneuvers: who is who and what is what?].

The original Valsalva manoeuvre (VM) was described in detail by the Italian anatomist, physician and surgeon Antonio Maria Valsalva (1666-1723). The VM consists of a voluntary forced expiratory effort against a closed upper airway. It was used tradionally in otolaryngology for testing the openess of the eustachian tubes and expelling pus/fluid from the middle to the external ear.

[The search for the "node of life": breathing regulation].

The article provides a historical overview of developments in the understanding of respiratory rhythm and its control mechanisms over the last two centuries. In the 19 century, a structure in the medulla oblongata was first described as the "node of life". In 1743, Taube discovered the carotid body, and in 1927 the Spaniard de Castro described its morphology and innervation.

[From "processing" and "fermentation" to oxidative metabolism].

The theory of the four humors or humorism (Hippocrates of Kos) viewed disease as an imbalance of the humors. Galen of Pergamon further developed the theory by describing digestion as a sequence of chemical reduction processes that convert into the various humours. Theophrastus von Hohenheim attempted to overcome humorism in the 16th century and establish medicine on a natural-philosophical-alchemical basis.

[The upper airway in obstructive sleep apnea patients is pathological even when awake].

Obstructive sleep apnea (OSA) is characterized by partial or complete obstruction of the pharyngeal airway. Anatomical factors can be distinguished from non-anatomical factors. Age and obesity are the main risk factors for OSA; however, approximately 50% of patients are not obese.

[Sleep disorders in patients with chronic tinnitus].

Tinnitus has a lifetime prevalence of 25% in Germany. A common comorbidity in chronic cases are sleep disorders. The aims of this study were to detect sleep disorders and to identify possible associations with tinnitus parameters.

[In commemoration of Adolf Kussmaul's 200th birthday: Describer of the Kussmaul Breathing and pioneer of endoscopy].

Adolf Kussmaul (1822-1902) studied medicine in Heidelberg. The name Kussmaul is known worldwide for the panarteritis nodosa, the pulsus paradoxus and the venous pulse in callous mediastinopericarditis as well as the high-frequency and deep breathing in diabetic ketoacidosis. Kussmaul was also a pioneer in the endoscopic diagnosis and treatment of diseases of the oesophagus and stomach.

[Why you should know the "nose cycle" as a pneumologist and sleep medicine specialist].

The nasal cycle refers to the anticyclic swelling and decongestion of the two nasal cavities that occur during the day and during sleep, while the overall nasal flow remains constant. The nasal cycle was first described by R. Kayser in 1895.