In a normal person, this redistribution of blood has little effect on respiratory function as the left ventricle has the adequate capacity to suddenly increase its stroke volume (as a result of the Frank-Starling mechanism). In a person with heart failure, the left ventricle has an inadequate capacity to respond to increased arrival of blood from the pulmonary circulation. This leads to the pooling up of blood in the pulmonary circulation and doesnt change its volume enough. The increased intra-parenchymal pulmonary intravascular pressure can also result in hydrostatic pressure related fluid transudation into the alveoli, thus causing cardiogenic pulmonary edema and further worsening shortness of breath. Thus, shortness of breath is commonly experienced after a reasonably short time lying near to flat for a person with left ventricular failure. This is different from the dyspnea experienced by someone with lung parenchymal pathology (both restrictive and obstructive) when lying down, which is sudden and instead related to an acute change in diaphragmatic/accessory respiratory muscle mechanical advantage lost when moving the body into a more horizontal position. Diagnosis
Diagnosis is based mostly on the clinical features and symptoms, as well as finding causes like heart failure. Treatment
Based on the cause, Orthopnea can be treated with respiratory support devices such as CPAP or biPAP while the disease causing it is addressed. Etymology
The word orthopnea uses combining forms of ortho- + -pnea, from Greek ortho, straight, regular, + pnoia, breath. See pronunciation information at dyspnea. See also
Paroxysmal nocturnal dyspnoea
Platypnea
Trepopnea
Bendopnea
Shortness of breath

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Rett syndrome (RTT) is a genetic disorder that typically becomes apparent after 6–18 months of age in females. Symptoms include impairments in language, coordination, and repetitive movements. Those affected often have slower growth, difficulty walking, and a smaller head size. Complications of Rett syndrome can include seizures, scoliosis, and sleeping problems. The severity of the condition is variable.Rett syndrome is due to a genetic mutation in the MECP2 gene, on the X chromosome. It almost always occurs as a new mutation, with less than one percent of cases being inherited from a persons parents. It occurs almost exclusively in girls; boys who have a similar mutation typically die shortly after birth. Diagnosis is based on the symptoms and can be confirmed with genetic testing.There is no known cure for Rett syndrome. Treatment is directed at improving symptoms. Anticonvulsants may be used to help with seizures. Special education, physiotherapy, and braces may also be useful. Many of those with the condition live into middle age.The condition affects about 1 in 8,500 females. In 1999, Lebanese-American physician Huda Zoghbi discovered the mutation that causes the condition. Signs and symptoms
Stage I
Stage I, called early-onset, typically begins between 6 and 18 months of age. This stage is often overlooked because symptoms of the disorder may be somewhat vague, and parents and doctors may not notice the subtle slowing of development at first. The infant may begin to show less eye contact and have reduced interest in toys.