A disposable manometer includes a chamber connectable to a source of respiratory gases via a patient breathing valve and a passageway. A pointer is rotatably disposed with respect to a dial to indicate pressure within the chamber. The pointer has an actuator stem with a spiral-shaped protrusion coupled to a groove within an opening of a stem coupling attached at the center of a diaphragm forming one wall of the chamber. Responsive to pressure entering the chamber, the diaphragm reciprocates against the force of a biasing non-magnetic resilient member moving the stem coupling with respect to the actuator stem of the pointer so that the interaction between the spiral-shaped protrusion and the groove causes rotation of the pointer to indicate the pressure within the chamber. The disposable manometer is useful with any source of respiratory gasses and in the vicinity of any strong magnetic field.