A surgical system includes a control assembly and a surgical instrument defining a gas inflow path, a gas outflow path, and an end effector configured to apply energy to tissue. The control assembly includes a gas output configured to connect to the gas inflow path, a gas input configured to connect to the gas outflow path, and an energy output configured to supply energy to the end effector. The control assembly further includes a controller to determine an amount of gas output from the gas output, determine an amount of gas withdrawn into the gas input, compare the amount of gas output and the amount of gas withdrawn, and control withdrawal of gas from the gas outflow path such that the amount of gas output and the amount of gas withdrawn are equal to one another or within a threshold margin of one another.
