A medical device including a portion similar to a Veress needle, useful for relief of tension pneumothorax. The device includes a hollow tubular stylet disposed movably within a hollow needle or cutting cannula, and an optionally releasable locking mechanism for keeping the stylet in place protruding distally beyond the sharpened distal end of the cutting cannula to prevent puncture of internal organs after the chest wall has been intentionally punctured. The stylet can also be moved outward from within the cannula to push a plug of tissue from the bore of the cannula. A valve or a connector for a tube may be provided at a proximal end of the stylet.