Time-limited methods for cryogenic treatment systems
Methods and apparatus for the treatment of a body cavity or lumen are described where a heated fluid and/or gas may be introduced through a catheter and into treatment area within the body contained between one or more inflatable/expandable members. The catheter may also have optional pressure and temperature sensing elements which may allow for control of the pressure and temperature within the treatment zone and also prevent the pressure from exceeding a pressure of the inflatable/expandable members to thereby contain the treatment area between these inflatable/expandable members. Optionally, a chilled, room temperature, or warmed fluid such as water may then be used to rapidly terminate the treatment session.
1. A method of treating tissue, comprising:
positioning an elongate probe into a body lumen to be treated;
expanding a liner enclosing the probe by infusing air into an interior of the liner with a sheath retracted to a first position relative to the liner;
further retracting the sheath to a second position relative to the liner corresponding to a portion of the body lumen to be treated such that the liner expands into contact against the portion of the body lumen;
adjusting a position of a delivery lumen relative to an infusion lumen which is positioned through or along the elongate probe while retracting the sheath to the second position such that one or more openings defined along a length of the infusion lumen remain unobstructed by the delivery lumen; and
infusing a cryoablative fluid comprising nitrous oxide in liquid form at a limited flow rate through the delivery lumen such that the fluid passes into the infusion lumen, through the unobstructed openings, and sprayed in liquid form into contact against the interior of the liner such that the interior becomes coated and a temperature within the interior of the liner drops to −89° C. within 6 to 7 seconds of introducing the fluid and whereby the nitrous oxide converts from the liquid, form to a gas form after contacting the interior of the liner.
2. The method of claim 1 wherein infusing a cryoablative fluid comprises infusing at a pressure of up to 150 mmHg and for a period of time of up to 150 seconds.
3. The method of claim wherein the infusion of the cryoablative fluid or gas is controlled via a controller.
4. The method of claim 1 further comprising ceasing the infusion of the cryoablative fluid into the interior of the liner.
5. The method of claim 4 wherein the air is infused into the interior of the liner for a period of time of up to 20 seconds.
6. The method of claim 1 further comprising detecting whether the pressure within the interior of the liner remains above a predetermined threshold over a period of 5 seconds to determine whether a leak is present within the liner.
7. The method of claim 1 further comprising detecting whether the pressure within the interior of the liner deviates over a predetermined amount over a period of time to determine whether a leak is present within the liner.
8. The method of claim 1 further comprising infusing air into the interior of the liner at a pressure of about 10 mmHg while the cryoablative fluid remains within the interior and then venting for about 2 seconds to thaw tissue in contact with an exterior of the liner.