Abstract: A physiological fluid sampling device connectable to a hypodermic needle has a sampling chamber of selectably variable volume defined by a sealing member in the form of a piston which is manually movable in a housing member due to its attachment to a plunger extending out of the housing member. The chamber is formed by a closed end of the housing, the housing side wall, and the sealing member, and a bore through the housing end wall permits fluid communication with the needle. The sealing member forms a constant hermetic seal around the housing side wall, but contaminant gases may escape from the chamber through exhaust passageways formed in the sealing member. Each of these passageways contains liquid reactive material so that they automatically seal upon contact with a physiological fluid, such as blood, to prevent re-entry of contaminant gases. Crystalline heparin coats the interior surface of the housing member to stop clotting of arterial blood.

Abstract: A physiological fluid sampling device connectable to a hypodermic needle has a sampling chamber of selectably variable volume defined by a sealing member in the form of a piston which is manually movable in a housing member due to its attachment to a plunger extending out of the housing member. The chamber is formed by a closed end of the housing, the housing side wall, and the sealing member, and a bore through the housing end wall permits fluid communication with the needle. The sealing member forms a constant hermetic seal around the housing side wall, but contaminant gases may escape from the chamber through exhaust passageways formed in the sealing member. Each of these passageways contains liquid reactive material so that they automatically seal upon contact with a physiological fluid, such as blood, to prevent re-entry of contaminant gases. Crystalline heparin coats the interior surface of the housing member to stop clotting of arterial blood.