The instrument has a separable body composed of two oblong interlinked members, each of them carrying at one of its vacant ends a detachable split bush adapted for the element being sutured to pass through the interior thereof and arranged across the longitudinal axis of the respective instrument body member. The bushes have flanges on the ends facing each other, each of the flanges having an open annular slot in the surfaces facing each other, and an opening made in the lateral face of the flange, the opening being communicated with the slot and with the tube that freely runs throughout the overall length of the instrument body and extends from it outwards so as to be connected to the vacuum device. The slots and openings in the bushes establish, along with the tubes, a system of air evacuation from the suturing zone, which is discarded along with the bush after the suturing procedure. One of the bushes has passages for the staples, while the other bush, a die for the staples to bend. A staple feeding mechanism is also provided.