A respiratory device may include an inlet port and an outlet port. A fluid pathway may extend between the inlet port and the outlet port. A filter housing may be positioned between the inlet port and the outlet port. A filter may be positioned within the filter housing. A first pressure port may be positioned on an inlet side of the filter housing. A second pressure port may be positioned on an outlet side of the filter housing. The first pressure port and the second pressure port may extend parallel to the fluid pathway. A pressure transducer may be coupled to the first pressure port and the second pressure port and configured to measure a pressure drop between the first pressure port and the second pressure port.
