Abstract: A spool valve assembly for a gaseous drug delivery device includes a housing, a gas inlet, a continuous flow orifice, a valve outlet, a valve mounting surface, a spool valve, a patient outlet, an exhaust chamber with a pressure sensor detecting inhalation and a gaseous drug path to the patient, and a control circuit connected to the pressure sensor. The gas inlet includes a port connected to a gaseous drug supply, with a first portion inside the housing and a second portion outside the housing. The valve mounting surface includes a mount for a high flow valve and a low flow valve, with the valve mounting surface between the gas inlet and the valve outlet. The spool valve includes a knob, an outer surface, sealing members and a counter bore, with a first portion of the knob inside the housing and a second portion outside the housing.

Abstract: A method for delivering a dose of a gaseous drug to a patient with a respiratory disorder including powering a control circuit via a power supply, determining a normal resting breath rate for the patient via the control circuit, determining a current breath rate for the patient via the control circuit, comparing the current breath rate to the normal resting breath rate; determining a dose of the gaseous drug for the patient based on the comparison, positioning a spool valve within a spool valve assembly; and delivering the determined dose through the low flow valve, the high flow valve, and/or a combination of the low flow valve and the high flow valve, and the continuous flow valve based on the position of a spool valve. The control circuit may control a low flow valve, a high flow valve, and a continuous flow valve.