Method and apparatus for pressure measurement
Methods and apparatus for measuring pressure in a patient are provided which may include any number of features. One feature is a pressure measurement system comprising a pressure source, a compliant bladder, a catheter in communication with the pressure source, pressure sensors, and a controller configured to determine a pressure within the compliant bladder. The pressure measurement system can inflate the compliant bladder with gas or air to determine a pressure within a patient. In one embodiment, the pressure measurement system measures pressure within a peritoneal cavity.
1. A pressure measurement system, comprising:
a catheter;
a pressure lumen disposed in the catheter and coupled to a pressure source;
a compliant bladder disposed on the catheter, the compliant bladder being in communication with the pressure lumen;
a retention balloon positioned proximal to the compliant bladder and configured to anchor the catheter within a patient body;
a pressure sensor coupled to the pressure lumen and configured to receive a pressure signal from the compliant bladder via the pressure lumen; and
a controller configured to receive the pressure signal from the pressure sensor and to control the pressure source to fill the compliant bladder with a volume of gas.
2. The system of claim 1 wherein the controller is programmed with instructions to execute a priming sequence, the instructions comprising:
commanding the pressure source to fill the compliant bladder with a first volume of gas; and
after filling the compliant bladder with the first volume of gas, commanding the pressure source to remove a second volume of gas from the compliant bladder so the complaint bladder becomes partially-filled.
3. The system of claim 1 wherein the controller is programmed with instructions to execute a priming sequence, the instructions comprising:
commanding the pressure source to fill the compliant bladder with gas until the complaint bladder reaches a first pressure; and
after reaching the first pressure, commanding the pressure source to remove a first volume of gas from the compliant bladder so the complaint bladder becomes partially-filled.
4. The system of claim 1 wherein the controller is programmed with instructions to execute a priming sequence, the instructions comprising:
commanding the pressure source to fill the compliant bladder with gas until the complaint bladder reaches a first pressure; and
after reaching the first pressure, opening the pressure source to atmospheric pressure for a first amount of time to remove gas from the compliant bladder until the complaint bladder becomes partially-filled.
5. The system of claim 1 wherein the catheter further comprises a fluid infusion lumen and a fluid extraction lumen.
6. The system of claim 5 wherein the pressure lumen is disposed in a divider between the fluid infusion lumen and the fluid extraction lumen.
7. The system of claim 5 wherein the pressure lumen is disposed in an interior wall of the catheter.
8. The system of claim 7 wherein a divider between the fluid infusion lumen and the fluid extraction lumen includes ridges to prevent total obstruction of fluid flow in the fluid infusion and extraction lumens during bending or kinking.
9. The system of claim 5 wherein the pressure lumen is free floating in the fluid infusion lumen.
10. The system of claim 1 further comprising a second pressure lumen coupled to the pressure source and in communication with the compliant bladder.
11. The system of claim 10 wherein the pressure lumen and the second pressure lumen are disposed on opposing sides of the catheter.
12. The system of claim 1 wherein the pressure lumen is disposed in an asymmetric wall of the catheter.
13. The system of claim 1 wherein the catheter includes four-extrusions connected end to end, wherein a first extrusion comprises the pressure lumen, and wherein a second, third, and fourth extrusion comprise infusion and extraction lumens.
14. The system of claim 13 wherein the infusion lumen occupies approximately one-third of a cross-sectional volume of the catheter.
15. The system of claim 2 wherein the instructions further comprise periodically repeating the priming sequence ensure accurate pressure measurements.
16. The system of claim 3 wherein the instructions further comprise periodically repeating the priming sequence to ensure accurate pressure measurements.
17. The system of claim 4 wherein the instructions further comprise periodically repeating the priming sequence to ensure accurate pressure measurements.
18. The system of claim 1 further comprising at least one displacement balloon in close proximity to the compliant bladder, the at least one displacement balloon configured to form a void around the compliant bladder.
19. The system of claim 1 wherein the controller is further configured to automatically detect when the catheter is connected to the controller.
20. The system of claim 19 wherein the controller is configured to detect when a predetermined pressure or volume is reached by the compliant bladder as an indication of the catheter being properly connected to the controller.