This work analyses the interaction of red blood cells (RBCs)with shock-induced and bubble-induced flows in shock wave lithotripsy (SWL),and calculates, in vitro, the lytic effects of these two flows.A well known experimentally observed fact aboutRBC membranes is that the lipid bilayer disrupts when subjectedto an areal strain (ΔA/A)c of 3%, and a corresponding, critical,isotropic tension, Tc, of 10 mN m-1 (1 mN m-1 = 1 dyne cm-1).RBCs suspended in a fluid medium tend to deform in accordancewith the deformation of the surrounding fluid medium.The fluid flow-field is lytically effective if the membrane deformationexceeds the above threshold value.From kinematic analysis, motion of an elementary fluid particle can always bedecomposed into a uniform translation, an extensional flow (e.g. u⃗∞(x,y,z) = (k(t)x,-k(t)y,0)) along three mutually perpendicularaxes, and a rigid rotation of these axes. However, only an extensional flowcauses deformation of a fluid particle, and consequently deforms the RBCmembrane. In SWL, a fluid flow-field, induced by a non-uniform shock wave, aswell as radial expansion/implosion of a bubble, has been hypothesized to causelysis of cells. Both the above flow-fields constitute an unsteady,extensional flow, which exerts inertial as well as viscous forces on the RBCmembrane. The transient inertial force (expressed as a tension, orforce/length), is given by Tiner~ρrc3k/τ, where τis a timescale of the transient flow and rc is a characteristic cell size.When the membrane is deformed due to inertial effects, membrane strain isgiven by ΔA/A~kτ. The transient viscous force is given byTvisc~ρ(ν/τ)1/2rc2k, where ρ and ν arethe fluid density and kinematic viscosity.For the non-uniform shock, the extensional flow exerts an inertial force,Tiner≈64 mN m-1, for a duration of 3 ns, sufficient toinduce pores in the RBC membrane. For a radial flow-field, induced by bubbleexpansion/implosion, the inertial forces are of a magnitude 100 mN m-1,which last for a duration of 1 µs, sufficient to cause rupture.Bubble-induced radial flow is predicted to be lytically more effective thanshock-induced flow in typical in vitro experimental conditions.