Pulmonary embolism is indicated by alterations in blood oxygen levels.
The Piney Point Lighthouse was built in 1836 located at Piney Point on the Potomac River in Maryland just up the river from the mouth of the Chesapeake Bay .. Piney Point. Piney Point, Maryland. Potomac River. Potomac River. Maryland. Maryland. Chesapeake Bay. Chesapeake Bay. The Coast Guard decommissioned it in 1964 and it has since become a museum .. It is known as the Lighthouse of Presidents because several early US Presidents visited or stayed on the grounds .