A device for the delivery or removal of energy to or from a region of a patient, the device comprising: a catheter shaft configured to be inserted into the patient to reach a treatment region; a first reagent positioned in the catheter shaft at about a distal region of the catheter shaft; a first lumen positioned within the catheter shaft configured to deliver a quantity of a limiting reagent to the distal region of the catheter shaft where the limiting reagent and the first reagent at least partially react with each other in a thermochemical reaction to produce a reaction product; a second lumen positioned within the catheter shaft configured to extract the reaction product from the distal region of the catheter shaft; a third lumen positioned within the catheter shaft configured to transport a heat transfer fluid, the heat transfer fluid configured to transfer energy between the treatment region and the reaction product; one or more sensors (181,182,183); and a handle attached at a proximal end of the catheter shaft, wherein the handle is configured to control at least one of a flow of the limiting reagent into the catheter shaft, a flow of the heat transfer fluid into the catheter shaft, and a flow rate of the reaction product, wherein the thermochemical reaction results in heating, cooling, or both; wherein the quantity of the limiting reagent provided at the distal region determines the amount of heating or cooling provided; and wherein the one or more sensors (181,182,183) are configured to verify an amount of heating or cooling and provide feedback to a user characterized in that the first reagent is maintained at the distal end of the catheter shaft within the second lumen. a catheter shaft configured to be inserted into the patient to reach a treatment region; a first reagent positioned in the catheter shaft at about a distal region of the catheter shaft; a first lumen positioned within the catheter shaft configured to deliver a quantity of a limiting reagent to the distal region of the catheter shaft where the limiting reagent and the first reagent at least partially react with each other in a thermochemical reaction to produce a reaction product; a second lumen positioned within the catheter shaft configured to extract the reaction product from the distal region of the catheter shaft; a third lumen positioned within the catheter shaft configured to transport a heat transfer fluid, the heat transfer fluid configured to transfer energy between the treatment region and the reaction product; one or more sensors (181,182,183); and a handle attached at a proximal end of the catheter shaft, wherein the handle is configured to control at least one of a flow of the limiting reagent into the catheter shaft, a flow of the heat transfer fluid into the catheter shaft, and a flow rate of the reaction product, wherein the thermochemical reaction results in heating, cooling, or both; wherein the quantity of the limiting reagent provided at the distal region determines the amount of heating or cooling provided; and wherein the one or more sensors (181,182,183) are configured to verify an amount of heating or cooling and provide feedback to a user characterized in that the first reagent is maintained at the distal end of the catheter shaft within the second lumen.