Rectal prolapse, 1356 , 1356 f Rectal thermometry, 194 Red-brown lesions, 445 Red cell aplasia, 419 Red cell distribution width (RDW), 423 Red eye, 171 f–172 f common causes of, 171 t evaluation and decision, 170 –174 diagnostic, 172 f life-threatening causes of, 171 t pathophysiology, 170 systemic conditions associated with, 171 t Referred ear pain, 393 Reflex neurovascular dystrophy (RND), 1378 Reflex sympathetic dystrophy (RSD), 1378 See also Complex regional pain syndrome type (CRPS1) Refractory shock, 72 Regional nerve blocks, 1129 Reiter syndrome, 383 t Remifentanil, 39 Renal and electrolyte emergencies acid–base homeostasis, disorders of goals of treatment, 976 metabolic acidosis, 976 –978 , 977 t metabolic alkalosis, 978 , 978 t acute kidney injury, 978 –980 intrinsic causes, 980 –985 calcium homeostasis, disorders of goals of treatment, 974 hypercalcemia, 975 –976 hypocalcemia, 974 –975 , 975 t chronic kidney disease, 987 –989 , 988 t emergency care, goals of, 965 hypovolemia and dehydration clinical considerations, 966 –969 estimated deficits and intravenous therapy, 967 t–968 t evidences, 965 –966