[Critical Closing Pressure (Pcrit) and Negative (Subatmospheric) Expiratory Pressure (NEP) for Diagnosis of Pharyngeal Collapsibility in Patients With Obstructive Sleep Apnea (OSA)]. / Kritischer Verschlussdruck (Pcrit) und negativer (subatmosphärischer) exspiratorischer Druck (NEP) zur Diagnostik der pharyngealen Kollapsibilität bei Patienten mit obstruktiver Schlafapnoe (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. Alternatively, Pcrit measurements can also be done during drug-induced sleep. A disadvantage of this method is the varying doses of propofol needed to induce sleep, which can affect muscle tone differently. As an alternative to these methods, the application of negative pressure during wakefulness (NEP test) has proven effective. In this test, the patient is administered a subatmospheric pressure of -5 or -10 cmH2O via mask at the beginning of expiration, and the change in expiratory airflow in the pharynx is measured. NEP test can be performed in both sitting and lying position. According to current knowledge, the NEP test appears to be a diagnostic procedure comparable to critical closing pressure (Pcrit) for assessing upper airway collapsibility.

An Interdisciplinary Approach: Presentation of the Pediatric Obstructive Sleep Apnea Diagnostic Examination Form (POSADEF).

This report emphasizes the need for interdisciplinary collaboration in diagnosing and treating pediatric obstructive sleep apnea (OSA). OSA, affecting 1% to 4% of children, often results from adenotonsillar hypertrophy, craniofacial disorders, or obesity. While adenotonsillectomy is the primary treatment, about 75% of children, especially those with craniofacial disorders or obesity, continue to experience OSA symptoms post-surgery. To address these cases, several medical fields emphasize the necessity and demand for interdisciplinary collaboration in managing pediatric OSA. Therefore, the authors aimed to develop the Pediatric Obstructive Sleep Apnea Diagnostic Examination Form (POSADEF). This form, based on clinical experience and the literature, captures craniofacial and functional characteristics linked to pediatric OSA. A case study of an eight-year-old girl with OSA, who was unsuccessfully treated with adenotonsillectomy, underlines the importance of the diagnostic examination form. The orthodontic assessment revealed craniofacial disorders and subsequent treatment with maxillary expansion and functional appliance therapy resolved her OSA symptoms. This case demonstrates the value of POSADEF in enabling comprehensive evaluation and treatment across medical disciplines. POSADEF is designed to assist health care professionals in diagnosing craniofacial and orofacial anomalies contributing to pediatric OSA.

[Valsalva and Müller maneuvers: who is who and what is what?] / Valsalva- und Müller-Manöver: Wer ist wer und was ist was?

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. VM is associated with increased intrathoracic and -abdominal pressure and leads to hemodynamic changes. The use of VM for cardiovascular purposes was first described by Eduard Friedrich Weber, a German physiologist. The Müller manoeuvre (MM) represents the opposite of the VM by forced inspiration against a closed upper airway. Negative intrathoracic and abdominal pressure (ITP) with direct effects on cardiac function and hemodynamics can be generated by the MM. MM has also been used to simulate the hemodynamic effects of negative ITP in obstructive sleep apnea patients. The Müller manoeuvre was first described by the German anatomist and physician Johannes Müller (1801-1858).

[The experimental physiologist Carl Ludwig (1816-1895): Scientific genius - modest, selfless, unswerving!] / Der Experimentalphysiologe Carl Ludwig (1816­1895): Wissenschaftlicher Genius ­ uneitel, selbstlos, unbeirrbar!

Carl Ludwig was, besides Johannes Müller, one of the most prolific natural scientists of the 19th century. Carl Ludwig believed that the function of organs can be ascribed to the laws of physics and chemistry and that only through repeatable physiological experiments can hypotheses be verified. Ludwig has laid the technological foundations for experimental physiology. The "kymographion", (waves-recorder), the "stromuhr" and the blood gas pump are some of his developments that underline this fact. Together with his students he performed fundamental experiments to gain better understanding of renal physiology and pulmonary physiology, cardiovascular circulatory and innervation, as well as glandular secretion and the lymphatic system. For decades, Ludwig's two-volume textbook on the human physiology was standard work in scientific and experimental physiology. Many young scientists from all over the world ventured to Leipzig to be taught experimental physiology by Ludwig.

[The upper airway in obstructive sleep apnea patients is pathological even when awake]. / Der obere Atemweg bei OSA-Patienten ist auch im Wachzustand pathologisch.

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. In older patients (>60 years), the importance of obesity decreases. There is an increased prevalence of OSA among patients with normal weight. The effects of chronic intermittent hypoxemia, low-grade inflammation, increased sympathetic tone and mechanical stress contribute to a transformation of muscle fibers in the upper airway, resulting in reduced muscle mass and strength. Less frequently encountered non-anatomical factors include decreased muscle tone, increased arousal threshold, and altered sensitivity of CO2 chemoreceptors.

[Sleep disorders in patients with chronic tinnitus]. / Schlafstörungen bei Patienten mit chronischem 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.Fifty patients with chronic tinnitus were recruited. The patients underwent audiometry, polysomnography, and completed standardised questionnaires on tinnitus and sleep behaviour.Data were available in 30 men and 9 women (age 50.2 ± 11 y, BMI 28.8 ± 4.4 kg/m²). The median duration of tinnitus was 36 (9; 120) months with a severity score of 2.00 (1.00; 3.00). The mean Tinnitus Questionnaire (TF) score was 43.6 ± 17.1, the Epworth Sleepiness Scale (ESS) score was 8.41 ± 4.27, the Pittsburgh Sleep Quality Index (PSQI) score was 9.21 ± 4.32, and the Screening Scale for Chronic Stress (SSCS) score was 58.13 ± 9.58.Sleep diagnoses included 18 cases of insomnia, 4 cases of RLS, and 11 cases of OSA. Patients with sleep comorbidities showed higher tinnitus severity, PSQI scores, and body weight compared to those without sleep disorders.Worse sleep quality was associated with higher tinnitus severity (p=0.038) and more disruptive tinnitus (p=0.03). Patients with subjectively highly disruptive tinnitus reported higher chronic stress scores. Tinnitus duration was correlated with OSA-severity (p=0.026).More than two-thirds of tinnitus patients showed sleep disorders as comorbidity. A sleep screening appears useful in cases of increased tinnitus severity. Whether CPAP therapy is helpful in reducing tinnitus symptoms could not be conclusively determined but deserves further attention.

[From "processing" and "fermentation" to oxidative metabolism]. / Über "Kochung" und "Gärung" zum oxidativen Stoffwechsel.

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 era of empirical-experimental chemically oriented medicine began with "iatrochemistry" in the 17th century. Franciscus Sylvius' concept of disease is based on an imbalance of acidic and alkaline fermentation. It was Lazarro Spallanzani who understood the digestive processes in the stomach as a chemical dissolution of food. The discovery of oxygen and the process of oxidation by Lavoisier laid the foundation for our understanding the physiology of metabolism.

Undiagnosed obstructive sleep apnea syndrome as a treatable cause of new-onset sleepiness in some post-COVID patients.

BACKGROUND AND PURPOSE: Infection with COVID-19 can lead to persistent sequelae, such as fatigue, daytime sleepiness or disturbed sleep, that can remain for more than 12 weeks and that are summarized as post-COVID syndrome. The causes remain unclear. The present study investigated the presence of sleep disorders in patients with post-COVID syndrome using polysomnography. METHODS: Thirty-four patients with post-COVID syndrome and new-onset fatigue and sleepiness after a SARS-CoV2 infection underwent polysomnography in accordance with American Association of Sleep Medicine (AASM) standards as part of their clinical workup. Analysis was performed visually based on AASM criteria (scoring manual version 2.6, 2020). RESULTS: Polysomnography revealed a sleep efficiency of <80% in 50% of patients and a mean respiratory disturbance index (RDI) of 9.9 ± 15.4/h. Excluding central apneas, 12 patients (35%) had an RDI of ≥5/h, pointing to obstructive sleep apnea syndrome (OSAS; AASM 2014). Patients with a high RDI were significantly older (p = 0.01) and showed a trend towards a higher body mass index (p = 0.08) than patients with a normal RDI but had no other risk factors for OSAS. Six patients agreed to long-term treatment of their OSAS and all reported discontinuation of daytime symptoms. CONCLUSIONS: Post-COVID symptoms such as daytime sleepiness, fatigue and memory and concentration problems may in part be a result of reduced sleep efficiency and sleep apnea in a relevant percentage of patients. This possibly treatable cause of the symptoms should be kept in mind in patients presenting with post-COVID syndrome.

[The search for the "node of life": breathing regulation]. / Die Suche nach dem "Knoten des Lebens" ­ die Atemregulation.

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 19th 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. It was only with the work of father and son Heymans that the physiological and pharmacological significance of the carotid and aortic body was recognized. Today we understand that the generation and control of respiration are mediated by a complex neuronal network in the brainstem. Chemo-, mechano- and proprioreceptos convey information from blood, airways and muscles to the control centre. The respiratory centre integrates the afferent input from the receptors, the autonomic nervous system, the cardiovascular system, and voluntary input from the cerebral cortex to modulate the degree of respiratory activation of motoneurons and respiratory muscles.

[Johannes Müller (1801-1858) and his school: pioneer and giant of German physiology]. / Johannes Müller (1801­1858) und seine Schule ­ Wegbereiter und Gigant der deutschen Physiologie.

Johannes Müller was indisputably the most versatile and brilliant physiologist in the mid-nineteenth century. Müller was born in Koblenz in 1801 as the eldest of five children. He received an excellent education in mathematics and the ancient languages and was thus able to read with ease the writings of Aristotle in the original.He served a year with the Pioneers after graduating from high school in 1818. In 1819 he enrolled at the University of Bonn. In 1821, while still a student, he was awarded the scientific university prize for his work on foetal respiration. Müller received his doctorate at the university of Bonn in 1822. He moved to Berlin, where he continued to attend lectures by the anatomist Karl Asmund Rudolphi.He obtained his habilitation in physiology and comparative anatomy in 1824. After his years in Bonn, he accepted a chair at the University of Berlin in 1833 as Rudolphi's successor. His famous "Handbuch der Physiologie" (1833-1840) was published in Berlin. Müller's main areas of interest were physiology, human anatomy, comparative anatomy and anatomical pathology.Müller has numerous publications in addition to his famous book on physiology. He and his distinguished students (Emil du Bois-Reymond, Ernst Haeckel, Hermann von Helmholtz, Friedrich Gustav Jakob Henle, Carl Ludwig, Theodor Schwann and Rudolf Virchow amongst others) made the Berlin Physiological Institute world famous. The natural-philosophical approach to medicine that was still dominant at the beginning of the 19th century was increasingly replaced by a scientifically oriented methodology by Müller.

Chronic cough in postmenopausal women and its associations to climacteric symptoms.

BACKGROUND: Postmenopausal women often have chronic cough. Hormonal changes might be affecting lung function and the mucous membrane of the airways, causing hypersensitivity of the cough reflex. Therefore, postmenopausal hormonal changes could play a key role in the association between increased cough and menopause. The aim of this study is to evaluate the relation of chronic cough and postmenopausal symptoms. METHODS: We performed a questionnaire-based cohort study in generally healthy postmenopausal women (age 45-65 years). Women with cough explained by a pre-existing diagnosis were excluded. Comorbidities, medication and baseline data were collected. The Menopause Rating Scale II (MRS II) was combined with the Leicester Cough Questionnaire. Groups were divided in chronic cough versus non-coughing participants, chronic cough was defined as symptoms over 8 weeks. We performed correlations and logistic regression for predicting cough based on postmenopausal symptoms. RESULTS: Sixty-six of 200 women (33%) reported symptoms of chronic cough over 8 weeks. No significant differences in baseline data (age, BMI, onset of menopause, years since menopause, concomitant diseases, and medication) were found between coughing and non-coughing women. The MRS II showed higher menopausal symptoms in patients with cough, with significant differences in 2 of the 3 MRS-domains (urogenital (p < 0.001) and somato-vegetative (p < 0.001)). Climacteric symptoms correlated strongly with parameters of cough (p < 0.001). On the basis of the MRS total score (p < 0.001) and the somato-vegetative and urogenital domains (p < 0.05), the prediction for respiratory complaints could be shown. DISCUSSION: Chronic cough was significantly associated with menopausal symptoms. Therefore chronic cough as a possible climacteric symptom and its underlying mechanisms should be further explored.

[Why you should know the "nose cycle" as a pneumologist and sleep medicine specialist]. / Warum man auch als Pneumologe und Schlafmediziner den "Nasenzyklus" kennen sollte.

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. Each cycle consists of a working phase and a subsequent resting phase, the purpose of which is the rehydration and regeneration of the mucosa. A nasal cycle occurs in about 70-90% of people. The duration of the phase is affected by age, body position, physical activity, mucociliary clearance and time of day. Typically, the cycle lengthens during sleep. Long-term rhinoflowmetry enables assessment of the circadian course of the alternating cyclic changes of the nasal mucosa.

[In commemoration of Adolf Kussmaul's 200th birthday: Describer of the Kussmaul Breathing and pioneer of endoscopy]. / Zum 200. Geburtstag von Adolf Kussmaul (1822­1902): Beschreiber der Kussmaul-Atmung und Wegbereiter der Endoskopie.

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. He had to close the medical practice he had started in 1850 in the black Forrest town of Kandern after three years, having developed health problems. Kussmaul's approach to his studies was clinical-scientific. In 1855, under the guidance of Virchow, he received his doctorate from the university of Würzburg. From 1859-1888 he held a chair in Erlangen, Freiburg and Strasbourg. He continued working as a physician after retirement at Heidelberg and wrote his memoirs "Jugenderinnerungen eines alten Arztes".

[Why the Wittenberg anatomist and scientist Konrad Victor Schneider (1614-1680) is also important for pneumologists]. / Warum der Wittenberger Anatom und Wissenschaftler Konrad Victor Schneider (1614­1680) auch für die Pneumologen bedeutsam ist.

The Wittenberg physician Konrad Victor Schneider (1614-1680) was the first to prove that mucus is not formed in the brain, nor is it secreted into the nasal cavity via the ethmoid bone. He recognised that there is no open anatomical connection between the brain and the nasal air space. Schneider discovered the sinonasal mucosa as the production site of mucus and thus refuted the hypothesis of cerebral mucus production and secretion by Hippocrates, Galen and Vesal. The nasal mucosa was named "membrana Schneideria" in honour of Schneider.

[Negative-pressure pulmonary edema and alveolar hemorrhage are potentially life-threatening complications of upper airway obstruction]. / "Negativdruck-Lungenödem" und "alveoläre Hämorrhagie" als Komplikationen einer oberen Atemwegsobstruktion.

Negative pressure pulmonary edema and alveolar hemorrhage are potentially life-threatening complications after relief of upper airway obstruction. The laryngeal-pharyngeal obstruction results in high negative intrapleural pressures. The increased intrapleural pressures affect the integrity of the alveolo-capillary membrane due to various factors. This review describes clinical symptoms, etiologic factors, pathophysiology and treatment strategies associated with each of these factors. The aim of this review is to equip clinicians with the knowledge base necessary to identify patients at increased risk for negative pressure pulmonary edema and alveolar hemorrhage.

[Analysis of Snoring in Patients with Obstructive Sleep Apnea (OSA) by Polysomnography and LEOSound]. / Die Analyse von Schnarchen bei Patienten mit obstruktiver Schlafapnoe (OSA) anhand von Polysomnographie und LEOSound.

INTRODUCTION: Snoring was monitored in patients with obstructive sleep apnea (OSA) using the LEOSound-Monitor and simultaneously polysomnographic (PSG) recording. In obstructive apneas snoring is normally apparent after apnea termination and the beginning of ventilation. We wanted to know how often obstructive apneas are terminated by ventilation in combination with snoring. METHODS AND INTENTION: In 40 patients with OSA (AHI > 15/h) simultaneous polysomnographic recordings were performed amongst long-term respiratory sound monitoring using the LEOSound monitor. Patients' average age was 57±11 years. Average weight was 100±19 kg by a mean body mass index (BMI) of 33±7 kg/m2. 12 out of 40 recordings had to be rejected for further analysis because of artifacts. Snoring recorded by polysomnography was compared with snoring monitored by LEOSound. RESULTS: 3778 obstructive apnea episodes were monitored. LEOSound identified snoring in 1921 (51,0%), polysomnography in 2229 (58,8%) obstructive apneas. Only in one patient there was a higher difference in snoring episodes between PSG and LEOSound. DISCUSSION: In nearly 60% of obstructive apnea events we found snoring during apnea-terminating hyperpnoea. LEOSound is a good diagnostic tool to monitor snoring. It is necessary to clarify why only 60% of all obstructive events/hyperpnoea develop snoring. From a pathophysiological point of view opening of collapsed upper airway should lead in a very high percentage to turbulences in airstream and committed snoring.

[Langhans' or Langerhans' cells? - The problem of the eponym]. / Langhans'sche oder Langerhans'sche Zellen? ­ Das Problem des Eponyms.

There is frequent confusion between Theodor Langhans (1839-1915) and Paul Langerhans (1847-1888) in the literature. Theodor Langhans was a German pathologist who discovered and described the "giant cells" with nuclei close to the outer membrane of the tubercles. Today, these cells are called "Langhans' giant cells". The eponym "Langerhans' cells" refers to dendritic cells in the stratum spinosum of the epidermis. Paul Langerhans described these cells for a competition organised by the Berlin Medical Faculty when he was still a student. Most doctors know Paul Langerhans through the first description of the "Langerhans' islet cells" of the pancreas. Langerhans died of tuberculosis at the age of 40 after a long exile on the island of Madeira.