A medical system, comprising: an ablation catheter including: an elongate shaft with a proximal end, a distal end and a lumen disposed between the proximal end and the distal end; an expandable element in fluid communication with the lumen; a first temperature sensor operable to measure a first temperature; a second temperature sensor operable to measure a second temperature, the first temperature sensor and the second temperature sensor being longitudinally separated from each other by at least a portion of the expandable element; and a control unit, the control unit configured to: deliver a continuous flow of inflation fluid to the expandable element; and determine an extent of occlusion of a blood vessel when the expandable element is inserted within the blood vessel and inflated, the determining based at least in part on a relationship between first temperature and the second temperature; the extent of occlusion in the blood vessel being at least one of complete occlusion, partial occlusion and no occlusion, and wherein the control unit is further configured to: increase the continuous flow of inflation fluid when it is determined that the extent of occlusion is one of complete occlusion. an ablation catheter including: an elongate shaft with a proximal end, a distal end and a lumen disposed between the proximal end and the distal end; an expandable element in fluid communication with the lumen; a first temperature sensor operable to measure a first temperature; a second temperature sensor operable to measure a second temperature, an elongate shaft with a proximal end, a distal end and a lumen disposed between the proximal end and the distal end; an expandable element in fluid communication with the lumen; a first temperature sensor operable to measure a first temperature; a second temperature sensor operable to measure a second temperature, the first temperature sensor and the second temperature sensor being longitudinally separated from each other by at least a portion of the expandable element; and a control unit, the control unit configured to: deliver a continuous flow of inflation fluid to the expandable element; and determine an extent of occlusion of a blood vessel when the expandable element is inserted within the blood vessel and inflated, the determining based at least in part on a relationship between first temperature and the second temperature; the extent of occlusion in the blood vessel being at least one of complete occlusion, partial occlusion and no occlusion, and wherein the control unit is further configured to: increase the continuous flow of inflation fluid when it is determined that the extent of occlusion is one of complete occlusion. deliver a continuous flow of inflation fluid to the expandable element; and determine an extent of occlusion of a blood vessel when the expandable element is inserted within the blood vessel and inflated, the determining based at least in part on a relationship between first temperature and the second temperature; the extent of occlusion in the blood vessel being at least one of complete occlusion, partial occlusion and no occlusion, and wherein the control unit is further configured to: increase the continuous flow of inflation fluid when it is determined that the extent of occlusion is one of complete occlusion.