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 in a cavity, comprising:
positioning a first valve in a first position of the first valve and a second valve in a second position of the second valve, wherein the first valve is positioned along a pump output pathway and the second valve is positioned along a pump input pathway, wherein the first position of the first valve fluidly couples a liner to a pump and the second position of the second valve fluidly couples an ambient environment to the pump;
positioning an elongate probe within an infusion lumen into a body lumen to be treated, wherein the liner encloses the elongate probe and where one or more pressure sensors are in fluid communication with the elongate probe;
drawing air through the second valve and into the liner via the pump and the first valve, wherein the air is drawn into the liner according to an algorithm wherein an initial increase in pressure is followed by a controlled increase in pressure more gradual than the initial increase in pressure;
detecting, using the one or more pressure sensors, whether a pressure within the liner is above a predetermined pressure threshold;
introducing a cryogenic fluid into the liner after the pressure within the liner reaches a predetermined holding pressure;
detecting, using the one or more pressure sensors, whether the pressure within the liner is above a maximum pressure threshold; and
in accordance with a determination that the pressure within the liner is above the maximum pressure threshold:
positioning the first valve in a second position of the first valve and the second valve in a first position of the second valve, wherein the second position of the first valve fluidly couples an ambient environment to the pump and the first position of the second valve fluidly couples the liner to the pump; and
evacuating the cryogenic fluid from the liner via the pump and the second valve such that the cryogenic fluid is exhausted via the first valve.
2 . The method of claim 1 , further comprising performing a check of the one or more pressure sensors by detecting an initial reading from each of the one or more pressure sensors and confirming that each of the initial readings falls within a predetermined range of pressures.
3 . The method of claim 2 , wherein performing a check of the one or more pressure sensors further comprises comparing each of the initial readings to each other from at least two pressure sensors to determine deviations between the initial readings.
4 . The method of claim 3 , further comprising comparing deviations between the initial readings between the at least two pressure sensors to perform the check of the one or more pressure sensors.
5 . The method of claim 1 , wherein the predetermined pressure threshold within the liner is 85 mmHg.
6 . The method of claim 1 , further comprising detecting for leaks in the liner when the pressure within the liner is below the predetermined holding pressure.
7 . The method of claim 6 , wherein the predetermined holding pressure within the liner is 40 mmHg or more.
8 . The method of claim 1 , further comprising detecting a pressure fault after introducing cryogenic fluid into the liner; and
stopping introduction of the cryogenic fluid when a pressure fault is detected.
9 . The method of claim 8 , wherein the pressure fault comprises a detected pressure of 150 mmHg or greater.
10 . The method of claim 8 , wherein the pressure fault comprises comparing a first pressure reading from a first pressure sensor of the one or more pressure sensors to a second pressure reading from a second pressure sensor of the one or more pressure sensors and determining a deviation between the first pressure reading and the second pressure reading.
11 . The method of claim 1 , wherein positioning the first valve in the first position of the first valve and the second valve in the second position of the second valve comprises automatically positioning the first valve and the second valve simultaneously or sequentially.
12 . The method of claim 11 , wherein automatically positioning comprises controlling the first valve and the second valve via a processor.
13 . The method of claim 1 , wherein drawing air comprises drawing the air via a non-reversible pump.
14 . The method of claim 1 , wherein the first valve and the second valve each comprises a 3-way solenoid valve.
15 . The method of claim 1 , wherein drawing air comprises drawing the air from an ambient environment through the second valve.
16 . The method of claim 1 , wherein, when the cryogenic fluid is introduced into the liner, the first valve is in the second position of the first valve and the second valve is in the second position of the second valve.
17 . The method of claim 1 , wherein introducing a cryogenic fluid comprises introducing nitrous oxide.
18 . The method of claim 1 , wherein positioning the first valve in the second position of the first valve and the second valve in the first position of the second valve comprises automatically positioning the first valve and the second valve simultaneously or sequentially.
19 . The method of claim 1 , wherein evacuating the cryogenic fluid comprises exhausting the cryogenic fluid into an ambient environment.
20 . The method of claim 1 , wherein the maximum pressure threshold is 150 mmHg or greater.