Within this context, the definition of an event depends on several factors (e.g., patients age) and account for this variability through a multi-criteria decision rule described in several, sometimes conflicting, guidelines. Oximetry
Oximetry, which may be performed over one or several nights in a persons home, is a simpler, but less reliable alternative to a polysomnography. The test is recommended only when requested by a physician and should not be used to test those without symptoms. Home oximetry may be effective in guiding prescription for automatically self-adjusting continuous positive airway pressure. Classification
There are three types of sleep apnea. OSA accounts for 84%, CSA for 0.9%, and 15% of cases are mixed. Obstructive sleep apnea
Obstructive sleep apnea (OSA) is the most common category of sleep-disordered breathing. The muscle tone of the body ordinarily relaxes during sleep, and at the level of the throat, the human airway is composed of collapsible walls of soft tissue that can obstruct breathing. Mild occasional sleep apnea, such as many people experience during an upper respiratory infection, may not be significant, but chronic severe obstructive sleep apnea requires treatment to prevent low blood oxygen (hypoxemia), sleep deprivation, and other complications. Individuals with low muscle-tone and soft tissue around the airway (e.g., because of obesity) and structural features that give rise to a narrowed airway are at high risk for obstructive sleep apnea. The elderly are more likely to have OSA than young people.
Hematemesis is the vomiting of blood. It is always an important sign. It can be confused with hemoptysis (coughing up blood) or epistaxis (nosebleed), which are more common. The source is generally the upper gastrointestinal tract, typically above the suspensory muscle of duodenum. It may be caused by ulcers, tumors of the stomach or esophagus, varices, prolonged and vigorous retching, gastroenteritis, ingested blood (from bleeding in the mouth, nose, or throat), or certain drugs.Hematemesis is treated as a medical emergency, with treatments based on the amount of blood loss. Investigations include endoscopy. Any blood loss may be corrected with intravenous fluids and blood transfusions. Patients may need to avoid taking anything by mouth. Definition
Hematemesis is the vomiting of blood. This is usually vomit that contains bright red blood. Coffee ground vomiting is similar to hematemesis, but is distinct in not involving bright red blood.Hematemesis is always an important sign. It must be differentiated from hemoptysis (coughing up blood) and epistaxis (nosebleed). Both of these are more common conditions. These may be difficult to distinguish. Differential diagnosis
Hematemesis may be caused by:

Peptic ulcer. This may be related to Zollinger–Ellison syndrome, which causes severe disease. Vascular malfunctions of the gastrointestinal tract, such as bleeding gastric varices or intestinal varices. Mallory-Weiss syndrome: bleeding tears in the esophagal mucosa, usually caused by prolonged and vigorous retching. Vomiting of ingested blood after bleeding in the mouth, nose, or throat. Tumors of the stomach or esophagus. Irritation or erosion of the lining of the esophagus or stomach. Radiation poisoning. Viral hemorrhagic fevers.