We are studying a sample of spiral galaxies which host nuclear starbursts. Our aim is first to detect supergalactic winds (SGWs) and second to establish the conditions needed for the onset of the supergalactic wind phase. In this contribution we present preliminary work on the galaxy NGC 4631. We analyze Fabry--Perot observations (TAURUS) taken at the 4.2~m William Herschel Telescope Roque de los Muchachos Observatory (ORM). Data have been complemented with long slit spectroscopy (ISIS) taken from the La Palm a (ORM) data archive. Recently X-ray observations from Chandra have evidenced the escaping of hot gas from the disk into the halo. We identify possible SGW features on both sides of the disk. Emission lines are split revealing outflows and blow-out into the galactic halo. More detailed analysis has been undertaken in order to decide wether or not the galaxy has an SGW. Typical sizes of split lines areas range from 55~pc (a bubble feature) to 142.5~pc, the largest extent. Velocities of split lines range from 40 km/s to 85 km/s.