common, 349 t life-threatening, 349 t differential diagnosis, 347 –352 , 349 t evaluation and decision, 352 –353 pathophysiology, 347 Oral mucosal soft tissue pathology, 1316 –1318 aphthous stomatitis, 1317 eruption cysts, 1317 , 1317 f mucocele, 1317 neonatal cysts, 1318 pyogenic granuloma, 1317 –1318 Riga–Fede disease, 1318 treatment goals, 1316 Oral phosphosoda, 132 Oral rehydration therapy (ORT), 149 –150 , 150 f Orbital blowout fractures, defined, 1124 , 1125 f Orbital cellulitis, 179 –180 See also Periorbital/orbital cellulitis Orbital dystopia, 1122 Orbital fracture, 1124 –1126 , 1124 f Orbital tumors, 175 , 180 Orbital wall fractures, 176 Orchiopexy, 257 Orchitis, 411 Order set, –11 Organic acidemias, 874 Organic psychosis, 95 t Organophosphates, 1065 Orifice odors, 338 Oropharyngeal airways (OPA), 48 , 48 f Oropharyngeal injuries, 625 –627 Oropharyngeal tumors, 909 Orthostatic hypotension, 492 , 518 , 520 , 522 , 524 , 539 Orthostatic intolerance, 520 –521 Oseltamivir, 81 t Osgood–Schlatter disease, 279 –280 , 301 –302 , 1367 , 1367 f Osler–Weber–Rendu disease, 166 Os odontoideum, 330