response to fluid flow from a catheter 12. Aspiration system 10 includes catheter 12, a fluid flow switch 14 coupled to catheter 12 through aspiration tubing 26, fluid flow sensor 16 coupled to fluid switch 14 through aspiration tubing 28, and a fluid pump 18 coupled to fluid flow sensor 16 through aspiration tubing 30. Unless otherwise indicated, FIG. 1 will be described with respect to fluid flow in a first flow direction from catheter 12 to fluid pump 18, as indicated by the “downstream” arrow; however, as will be described below, fluid flow may proceed in a second flow direction, opposite the first flow direction. [0046] Aspiration system 10 may be configured to draw fluid from catheter 12 into fluid pump 18. For example, a fluid, such as blood, an aspiration fluid, or a mixture thereof, may be drawn into at least one distal opening 36 of catheter 12 by negative pressure created by pump 18, distal opening 36 being an opening to the inner lumen of catheter 12. For example, the fluid may flow from catheter 12 through aspiration tubing 26, fluid flow switch 14, aspiration tubing 28, fluid flow sensor 16, and aspiration tubing 30 into fluid pump 18. [0047] Aspiration system 10 includes catheter 12 upstream of fluid flow sensor 16. Catheter 12 includes an elongated body and a hub. The elongated body of catheter 12 is configured to be advanced through vasculature of a patient via a pushing force applied to a proximal portion of the elongated body with minimal or no buckling, kinking, or otherwise undesirably deforming (e.g., ovalization). Catheter 12 may include an inner liner, an outer jacket, and a structural support member, such as a coil and/or or a braid, positioned between at least a portion of the inner liner and at least a portion of the outer jacket. Catheter 12 may include other structures, such as an expandable member configured to radially expand within a vessel of a patient, e.g., to engage a clot within the vessel. Catheter 12 may define at least one inner lumen. [0048] Catheter 12 may be used as an aspiration catheter to remove a thrombus, such as a clot or other material such as plaques or foreign bodies, from vasculature of a patient. In such examples, a negative pressure may be applied, such as by fluid pump 18, to the proximal end of catheter 12 to draw a thrombus into the inner lumen of catheter 12 through one or more distal openings 36. An aspiration catheter may be used in various medical procedures, such as a medical procedure to treat an ischemic insult, which may occur due to occlusion of a blood vessel (arterial or venous) that deprives brain tissue, heart tissue or other tissues of oxygen-carrying blood.