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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Even if different mechanisms of various interactions during sleep are known, it is still unsolved by which mechanisms physiological reactions during sleep may start a pathophysiological course. Hypoxia, Hypercapnia and repetitive sympathetic elevations are well known elements in the control of the arterial resistance. Furthermore investigations in patients with sleep apnea showed changes of the pulsatile secretion pattern within the renin-angiotensin-system and the antinatriuretic peptides. These changes were reversible under nasal CPAP-therapy, nycturia as a frequent symptom disappeared. Nevertheless neither hypoxia nor intrathoracic pressure changes nor the arousals can assert the longterm influence on the blood pressure alone, a multifactorial confluence must be assumed. Further it is unclear how a tonic increase of the arterial blood pressure may occur in dependence of the REM- and NREM-sleep cycle changes as well as during daytime. First investigations in sleeping man seem to indicate, that a disturbance of the physiological coupling of breathing and circulation may present a pathogenetic element. Finally it remains open, whether the changes of the cardiorespiratory coupling during sleep of control persons and of patients with OSA are comparable, and whether they may be procured for an explanation of the pathogenesis of arterial and pulmonary hypertension. Further investigations in the control mechanisms of breathing and circulation related to the circuits of chemo- and baroreception, thresholds during wakefulness and sleep may be of decisive help to process the question, to what extent clinical states find a correlate in a disturbed cardiorespiratory coupling and, much more significantly, whether a disturbance in the physiological cardiorespiratory coupling appears already in early states of a disease. Sleep with ist complex physiology as well as with its characteristic pathophysiological phenomenon of sleep related breathing disorders has opened a new interdisciplinary field where tools like the polysomnography and electronic data analysis are used by physiologists, pathophysiologists as well as by physicians.
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PMID:[Cardiorespiratory coupling in obstructive sleep apnea (OSA)]. 924 90

Patients suffering from neuromuscular diseases and thoracic deformities may develop global respiratory failure during their illness. We wanted to judge clinical parameters and information from the patients' medical history to reliably, quickly and noninvasively diagnose a ventilatory failure. Therefore we evaluated 105 situations with and without mechanical ventilation from 29 patients with indication for noninvasive nocturnal mask ventilation. 6 clinical parameters (e.g. heart rate, oxygen saturation, relative vital capacity), 2 test results (pH and partial pressure of carbon dioxide (pCO2)) and 6 parameters from the patients' medical history (e.g. nycturia, frontal headache in the morning, breathlessness) were investigated. After statistical evaluation we could show a relation between heart rate and pCO2 (Spearman's correlation: r = 0.331, p = 0.001, n = 105; one-tailed significance: r = 0.335, p = 0.038, n = 29). Significant differences between the groups of nycturia incidence indicate a tight relation between the incidence of nycturia and the height of hypercapnia levels (ANOVA--analysis of variance: p = 0.001). Using logistic regression we could show that information regarding medical history, especially nycturia, frontal headache and indrawings, gives important indications for global respiratory failure (sensitivity 97.62-100%, specificity 57.14-76.19%). Pathogenesis needs to be elaborated further.
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PMID:[Importance of medical history in diagnosis of respiratory insufficiency in patients suffering from neuromuscular diseases and thoracic deformities]. 1138 81

Obstructive sleep apnoea may be accompanied by various cardiovascular consequences resulting from alteration of the activity of the autonomous nervous system. These changes are mediated by: a--hypoxemia developing during the apnoea, b--severe hypoxemia, hypercapnia and acidosis in postapnoea, c--powerful but ineffective ventilatory efforts causing arousal and stimulation of the cardioexcitatory and vasomotor centres. There are four main pathogenetic mechanisms implementing the cardiovascular changes: 1--Functional alteration in the conduction system and the myocardium resulting in nocturnal cardiac dysrhythmias. 2--Vasoconstriction manifesting as angina pectoris, myocardial infarction, brain attacks and pulmonary or systemic hypertension. 3--Pulmonary congestion leading to cardiac or bronchial asthma or even lung oedema. 4--Neuroendocrine activation, including the sympathetic nervous system, renin-angiotensin-aldosterone system, atrial natriuretic peptide and erythropoietin, which may result in nycturia, nocturnal hypotension and diurnal hypertension.
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PMID:[Mechanisms in the development of cardiovascular complications in obstructive sleep apnea]. 1170 79