Classification of sleep disorders
S.R. Pandi-Perumal, Meera Narasimhan, Milton Kramer in Sleep and Psychosomatic Medicine, 2017
Sleep disorders have had a formal classification since 1979, when the Association of Sleep Disorder Centers published the Classification of Sleep and Arousal Disorders in the journal Sleep. The diagnosis rests upon a sleep symptom of difficulty initiating sleep, difficulty maintaining sleep, -morning awakening and, mainly for pediatric age groups, resistance to going to bed and difficulty in sleeping without a caregiver intervention. The sleep-related breathing disorders section is organized into main categories: obstructive sleep apnea disorders, central sleep apnea syndromes, sleep-related hypoventilation disorders, and sleep-related hypoxemia disorder. Sleep-related hypoventilation disorders consist of seven disorders that meet diagnostic criteria for sleep-related hypoventilation with or without oxygen desaturation. Hypersomnia due to a medication or substance is sleepiness that occurs as a consequence of a medication or substance or withdrawal from a wake-promoting medication or substance. Sleep-related abnormal sexual behaviors is listed as a subtype to be classified under confusional arousals.
Assessment of ventilation
Jonathan Dakin, Mark Mottershaw, Elena Kourteli in Making Sense of Lung Function Tests, 2017
Ventilation refers to the rate at which air is breathed in and out of the lungs. Alveolar ventilation is a parameter of fundamental importance, as it is the primary determinant of arterial CO2 concentration. Although each breath contains around 500 mL, approximately 150 mL do not reach the alveoli but remain within the dead space, which is comprised of the trachea and major airways. Because of the very large volume of CO2 held buffered in the body, it takes 20-30 minutes for a new steady state to be reached after a change in ventilation. There is increasing interest in use of venous blood gases for monitoring of PCO2 and pH in patients with acute respiratory failure, as these values correlate somewhat to the respective arterial values. Hypoventilation of gas-exchanging alveoli is the commonest mechanism of hypercapnia. Although chronic obstructive pulmonary disease is the commonest cause of hypercapnia, familiarity with this condition frequently leads doctors to miss other causes of hypercapnia.
Pyloric Stenosis
T.M. Craft, P.M. Upton in Key Topics In Anaesthesia, 2021
The stenosis is caused by a gross thickening of the circular muscle of the pylorus of unknown aetiology. The typical presenting symptoms are of weight loss and projectile vomiting after feeds. Signs include those of dehydration, visible gastric peristalsis, and a palpable tumour in the epigastrium. Ultrasound can be used to confirm the diagnosis. Vomiting produces a loss of gastric hydrogen and chloride ions resulting in a metabolic hypochloraemic alkalosis. The initial response of the kidney is to conserve potassium and hydrogen and to excrete an alkaline urine. As dehydration continues, however, the kidney begins to conserve sodium and chloride and to excrete hydrogen and potassium ions, thus exacerbating the alkalosis. The compensatory response to these metabolic changes is hypoventilation. Pyloromyotomy should not be performed as an emergency. Rehydration and correction of metabolic imbalance must occur preoperatively.
Hypoventilation
Published in Postgraduate Medicine, 1961
Alveolar hypoventilation results from a marked reduction in tidal volume or a considerable increase in physiologic dead space, either of which causes decreased arterial oxygen saturation and increased carbon dioxide retention. Respiratory depressants, diseases of the central nervous system, diffuse obstructive emphysema, obesity, chest wall deformity, pleural thickening, and weakness of respiratory muscles are the chief causes of hypoventilation. The use of oxygen therapy and dichlorophenamide has proved of benefit in treating chronic hypoventilation. Treatment of acute hypoventilation is based on improving oxygenation and alveolar ventilation and decreasing acidity.
Non-invasive Positive Airway Pressure in Obesity Hypoventilation Syndrome and Chronic Obstructive Pulmonary Disease: Present and Future Perspectives
Published in COPD: Journal of Chronic Obstructive Pulmonary Disease, 2017
Victor R. Ramírez-Molina, Francisco J. Gómez-de-Terreros, Javier Barca-Durán, Juan F. Masa
ABSTRACT Obesity hypoventilation syndrome (OHS) is a sleep disorder that has acquired great importance worldwide because of its prevalence and association with obesity leading to increased morbidity and mortality with reduced quality of life. The primary feature is insufficient sleep-related ventilation, resulting in abnormally elevated arterial carbon dioxide pressure (PaCO2) during sleep and demonstration of daytime hypoventilation. There are three main mechanisms that can generate diurnal hypoventilation in obese patients: alteration of the respiratory mechanics secondary to obesity; central hypoventilation secondary to leptin resistance and sleep disorder with sleep hypoventilation and obstructive apnoeas, which can be potentially solved with the use of positive airway pressure: non-invasive ventilation (NIV) and continuous positive airway pressure (CPAP). There are no established guidelines for the treatment of OHS, and only a few randomised controlled trials have been published. In this review, we have gone over the role of positive airway pressure, in particular the mechanisms that produce improvement, ventilatory modes available, clinical applications, technical considerations and future research. In addition, we added a review on NIV efficacy in chronic obstructive pulmonary disease (COPD), both in acute respiratory failure due to exacerbation and mainly in stable setting where more controversy and scientific contributions are coming.
Obesity hypoventilation syndrome: therapeutic implications for treatment
Published in Expert Review of Respiratory Medicine, 2010
Obesity hypoventilation syndrome occurs in obese individuals who are unable to compensate for the added load of obesity on the respiratory system, with resultant daytime hypercapnia in the absence of other causes of alveolar hypoventilation. Significant morbidity and mortality is seen in this disorder if appropriate treatment is not undertaken. Unfortunately, the diagnosis is frequently missed despite these individuals being heavy users of healthcare resources. The pathogenesis of obesity hypoventilation syndrome is multifactorial, but reversal of sleep-disordered breathing or significant weight loss improves respiratory function and daytime ventilation. However, a paucity of well-designed clinical trials and the absence of data from long-term follow-up means that comparison between various treatment options is not possible. Consequently, evidence-based treatment guidelines are currently lacking.
Related Knowledge Centers
- Hypercapnia
- Stroke
- Medicine
- Brainstem
- Gas Exchange
- Ventilation
- Respiratory Acidosis