Method and device for verification of intra-luminal placement and patency for vascular access devices
Methods, apparatus, and systems to non-invasively determine intra-luminal placement and patency of a vascular access device. In one form, our device itself remains non-invasive, connecting at the vascular access device's hub outside the patient's body. Patency and/or placement are estimated indirectly by measuring a physiological parameter which is indicative of proper patency and/or placement of the vascular access device in a patient. The measurement is compared to a reference value or calibration. If the comparison indicates indication of proper patency and/or placement, a signal is generated. The signal can be used in a number of ways. One example is to give a user-perceivable alarm or indication of proper patency and/or placement. Non-limiting examples include activating a light, an audible buzzer, a vibration, readable displayed text or graphics, or some combination of the same. The user can then have an indirect and at least semi-automatic way of estimating proper patency and/or placement of a vascular access device. In one aspect of the invention, the technique is able to achieve this end by monitoring and detecting changes in the physiological parameter of systemic vascular pressure via pressure measurement in, at, or near the hub or other portion of a vascular access device that has a lumen placed intra-luminally, and then using the results of that monitoring to indirectly transduce conditions or states indicative of either good placement/patency or bad placement/patency of the vascular access device.
1. An apparatus for automatic estimation of proper patency and placement of an intravascular lumen of a vascular access device in a patient, the apparatus configured for attachment to a proximal end of the vascular access device disposed outside of the patient in use, the apparatus comprising:
a. a sensor comprising:
i. a mounting end configured to sealingly mount the sensor to the proximal end of the vascular access device; and
ii. a sensing element responsive to variations in pressure from fluid or gas phase substances in the intravascular lumen of the vascular access device, the sensing element producing an electrical signal comprising one or more measurements of pressure in the intravascular lumen of the vascular access device; and
b. a circuit operably connected to the sensor, the circuit configured to:
i. acquire and quantify the one or more measurements of pressure in the intravascular lumen resulting in one or more quantified measurements;
ii. compare the one or more quantified measurements to a reference or calibration of a physiological parameter to produce variations in pressure in the intravascular lumen of the vascular access device to indicate a status of patency or placement of the vascular access device in the patient; and
iii. generate a signal based on the status of patency or placement of the vascular access device in the patient that outputs in user-perceivable form.
2. The apparatus of claim 1 , wherein the physiological parameter comprises intravascular pressure during respiration of a human or animal.
3. The apparatus of claim 1 , wherein the sensor comprises a load cell exposed directly or indirectly to pressure in the intravascular lumen.
4. The apparatus of claim 3 , wherein the load cell is either:
a. at or integrated with the vascular access device;
b. spaced from the vascular access device.
5. The apparatus of claim 4 , wherein the load cell produces in analog form the quantified measurements, and the circuit converts the analog form to digital form for processing by a microprocessor.
6. The apparatus of claim 5 , wherein the microprocessor is programmed to compare the digital form of the quantified measurements with a reference or calibration of a time-based waveform indicative of pressure variations over time of intravascular pressure during respiration of the intravascular lumen of the vascular access device indicative of proper patency or placement.
7. The apparatus of claim 6 , wherein the reference or calibration is based on at least one of:
a. central, peripheral, arterial, or venous vasculature of the patient;
b. ventilated respiration;
c. non-ventilated respiration;
d. active respiratory activity; or
e. passive respiratory activity.
8. The apparatus of claim 1 , wherein the signal comprises a user-perceivable alarm or indication.
9. The apparatus of claim 8 , wherein the user-perceivable alarm or indication comprises:
a. a light,
b. an audible buzzer,
c. a vibration,
d. readable displayed text or graphics, or
e. some combination of the same.
10. A system comprising the apparatus of claim 1 in combination with a processing unit comprising:
i. a microprocessor;
ii. a transducer of the sensed parameter into a digital signal useable by the microprocessor;
iii. on-board digital storage; and
iv. on-board communication output.
11. A kit comprising pre-selected components of the system of claim 10 , wherein the kit is packaged for use by a health care professional.