Homeless people are more likely to suffer injuries and medical problems from their lifestyle on the street, which includes poor nutrition, exposure to the severe elements of weather, and a higher exposure to violence. Yet at the same time, they have reduced access to public medical services or clinics, in part because they often lack identification or registration for public healthcare services. There are significant challenges in treating homeless people who have psychiatric disorders because clinical appointments may not be kept, their continuing whereabouts are unknown, their medicines may not be taken as prescribed, medical and psychiatric histories are not accurate, and other reasons. Because many homeless people have mental illnesses, this has presented a crisis in care.The conditions affecting homeless people are somewhat specialized, and have opened a new area of medicine tailored to this population. Skin conditions, including scabies, are common, because homeless people are exposed to extreme cold in the winter, and have little access to bathing facilities. They have problems caring for their feet, and have more severe dental problems than the general population. Diabetes, especially untreated, is widespread in the homeless population. Specialized medical textbooks have been written to address this for providers.Due to the demand for free medical services by homeless people, it might take months to get a minimal dental appointment in a free-care clinic. Communicable diseases are of great concern, especially tuberculosis, which spreads more easily in crowded homeless shelters in high-density urban settings.
In medicine, hepatopulmonary syndrome is a syndrome of shortness of breath and hypoxemia (low oxygen levels in the blood of the arteries) caused by vasodilation (broadening of the blood vessels) in the lungs of patients with liver disease. Dyspnea and hypoxemia are worse in the upright position (which is called platypnea and orthodeoxia, respectively). Pathophysiology
The hepatopulmonary syndrome results from the formation of microscopic intrapulmonary arteriovenous dilatations in patients with both chronic and far less common, acute liver failure. The mechanism is unknown but is thought to be due to increased liver production or decreased liver clearance of vasodilators, possibly involving nitric oxide.The dilation of these blood vessels causes overperfusion relative to ventilation, leading to ventilation-perfusion mismatch and hypoxemia. There is an increased gradient between the partial pressure of oxygen in the alveoli of the lung and adjacent arteries (alveolar-arterial [A-a] gradient) while breathing room air. Patients with HPS have platypnea-orthodeoxia syndrome (POS); that is, because intrapulmonary vascular dilations (IPVDs) predominate in the bases of the lungs, standing worsens hypoxemia (orthodeoxia)/dyspnea (platypnea) and the supine position improves oxygenation as blood is redistributed from the bases to the apices. Additionally, late in cirrhosis, it is common to develop high output failure, which would lead to less time in capillaries per red blood cell, exacerbating the hypoxemia. Diagnosis
The hepatopulmonary syndrome is suspected in any patient with known liver disease who reports dyspnea (particularly platypnea). Patients with clinically significant symptoms should undergo pulse oximetry. If the syndrome is advanced, arterial blood gasses should be measured on air.