The respiratory conduit includes at least two air flow control devices, wherein the at least one airflow control device is configured to withdraw {HEAD ~ air} from {TAIL ~ at least one location} within the respiratory conduit 
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The respiratory conduit includes at least two air flow control devices , wherein the at least one airflow control device is configured to withdraw { HEAD ~ air } from { TAIL ~ at least one location } within the respiratory conduit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH