An apparatus which provides controlled and consistent push-pause pulsatile flow of sufficiently turbulent flushing pressure and flow within a catheter system to purge a line of unwanted residue, said apparatus comprising: a) an automatic pulsing device which comprises i) a proximal connection into which flush liquid from a flush liquid source is provided; ii) a check valve distal from proximal connection which obstructs backflow of flush liquid and retards inflow of flush liquid into the automatic pulsing device to a predetermined level of flow; iii) a distal output port and connector for connection to the catheter system; iv) a pressure sensitive valve disposed to open and close output port and connector; and v) a pulse reservoir chamber disposed between pressure sensitive valve and check valve which contains a piston and a spring; and b) a pump or piston configured to deliver the flush liquid under pressure from a container to automatic pulsing device and pulse reservoir chamber through proximal connection, thereby compressing spring to provide a source of stored energy to spring and storing a volume of flush liquid within pulse reservoir chamber when pressure sensitive valve is closed; characterised that in use spring is decompressed and check valve is closed when pulse reservoir chamber is empty, and pressure sensitive valve opens when spring is compressed to discharge the pressurized flush liquid from automatic pulsing device through pressure sensitive valve and output port and connection; and pressure sensitive valve opens at a first predetermined flush liquid pressure in automatic pulsing device to produce a turbulent flow of liquid from automatic pulsing device through output port and connector and has an opening to closing pressure hysteresis such that pressure sensitive valve is closed at a second predetermined flush liquid pressure which is lower than the first predetermined flush liquid pressure. a) an automatic pulsing device which comprises i) a proximal connection into which flush liquid from a flush liquid source is provided; ii) a check valve distal from proximal connection which obstructs backflow of flush liquid and retards inflow of flush liquid into the automatic pulsing device to a predetermined level of flow; iii) a distal output port and connector for connection to the catheter system; iv) a pressure sensitive valve disposed to open and close output port and connector; and v) a pulse reservoir chamber disposed between pressure sensitive valve and check valve which contains a piston and a spring; and i) a proximal connection into which flush liquid from a flush liquid source is provided; ii) a check valve distal from proximal connection which obstructs backflow of flush liquid and retards inflow of flush liquid into the automatic pulsing device to a predetermined level of flow; iii) a distal output port and connector for connection to the catheter system; iv) a pressure sensitive valve disposed to open and close output port and connector; and v) a pulse reservoir chamber disposed between pressure sensitive valve and check valve which contains a piston and a spring; and b) a pump or piston configured to deliver the flush liquid under pressure from a container to automatic pulsing device and pulse reservoir chamber through proximal connection, thereby compressing spring to provide a source of stored energy to spring and storing a volume of flush liquid within pulse reservoir chamber when pressure sensitive valve is closed;