Patient monitoring systems, devices, and methods
Various patient monitoring systems, devices, and methods are disclosed for monitoring physiological parameters of a patient. A noninvasive blood pressure monitor can include an inflatable cuff, a pressure transducer, an air pump, and a plurality of air paths connecting the inflatable cuff, the pressure transducer, and the air pump. The monitor can also include an acoustic filter provided along at least one of the air paths. In some cases, the monitor can include first and second air pumps, as well as a processor to independently control operating characteristics of the air pumps. The processor can also control the air pumps so as to provide a first inflation rate for the inflatable cuff during a non-measurement portion of an inflation phase and a second, higher inflation rate during a measurement portion of the inflation phase.
1. A noninvasive blood pressure monitor comprising:
an inflatable cuff;
a pressure transducer;
two or more air pumps, each of the air pumps having an operating speed;
a plurality of air paths connecting the inflatable cuff, the pressure transducer, and the air pumps;
an acoustic filter provided along at least one of the air paths; and
a controller configured to determine one or more characteristics of acoustic noise produced by the first and second air pumps and to independently adjust the one or more operating characteristics of the first and second air pumps based on the one or more characteristics of the acoustic noise,
wherein the controller is further configured to adjust the one or more operating characteristics of the first and second air pumps based on the one or more characteristics of the acoustic noise so as to reduce an acoustic displeasure metric, the acoustic displeasure metric being based on a beat frequency in the acoustic noise produced by the first and second air pumps.
2. The noninvasive blood pressure monitor of claim 1 , wherein the acoustic filter comprises a low-pass filter.
3. The noninvasive blood pressure monitor of claim 1 , wherein the acoustic filter comprises one or more stubs branching off from one of the plurality of air paths.
4. The noninvasive blood pressure monitor of claim 3 , wherein the one or more stubs are straight.
5. The noninvasive blood pressure monitor of claim 3 , wherein the one or more stubs are closed-ended.
6. The noninvasive blood pressure monitor of claim 3 , wherein the acoustic filter comprises two opposing stubs.
7. The noninvasive blood pressure monitor of claim 3 , wherein the one or more stubs have a folded configuration.
8. The noninvasive blood pressure monitor of claim 7 , wherein the one or more stubs include a plurality of sections joined together at one or more angles.
9. The noninvasive blood pressure monitor of claim 1 , wherein the acoustic filter comprises one or more box-shaped cavities.
10. The noninvasive blood pressure monitor of claim 9 , wherein the acoustic filter comprises a box-shaped cavity with a face attached to one of the plurality of air paths.
11. The noninvasive blood pressure monitor of claim 9 , wherein the acoustic filter comprises a box-shaped cavity attached to one of the plurality of air paths by a stub.
12. The noninvasive blood pressure monitor of claim 1 , further comprising:
a housing with two or more parts; and
a gasket provided at a mating interface between the two or more parts.
13. The noninvasive blood pressure monitor of claim 12 , further comprising noise-dampening material inside the housing.
14. The noninvasive blood pressure monitor of claim 1 , wherein the acoustic filter has a pass band that excludes a fundamental frequency produced by the two or more air pumps when operating.
15. The noninvasive blood pressure monitor of claim 1 , further comprising an air manifold that joins the plurality of air paths.
16. The noninvasive blood pressure monitor of claim 15 , wherein the acoustic filter is provided between the air pump and the air manifold.
17. The noninvasive blood pressure monitor of claim 15 , wherein the acoustic filter is provided between the inflatable cuff and the air manifold.
18. The noninvasive blood pressure monitor of claim 15 , wherein the acoustic filter is provided between the pressure transducer and the air manifold.
19. The noninvasive blood pressure monitor of claim 15 , wherein the acoustic filter is integrated with the air manifold.
20. The noninvasive blood pressure monitor of claim 19 , wherein the air manifold comprises an acoustic filtering cavity.
21. The noninvasive blood pressure monitor of claim 20 , wherein the acoustic filtering cavity includes a plurality of ports that feed into the acoustic filtering cavity, and wherein a dimension of the acoustic filtering cavity is at least 5 times a dimension of the plurality of ports.
22. The noninvasive blood pressure monitor of claim 1 , wherein the controller is further configured to alter an inflation rate for the inflatable cuff by turning one or more of the air pumps on at its operating speed or by turning one or more of the air pumps off.
23. The noninvasive blood pressure monitor of claim 22 , wherein the controller is configured to not alter the inflation rate by altering the operating speed of the two or more air pumps.
24. The noninvasive blood pressure monitor of claim 22 , wherein the controller is configured to operate two air pumps at the operating speed and to approximately halve the inflation rate by turning one of the air pumps off.
25. The noninvasive blood pressure monitor of claim 22 , wherein the controller is configured to operate one air pump at the operating speed and to approximately double the inflation rate by turning another air pump on.
26. The noninvasive blood pressure monitor of claim 1 , wherein the controller is configured to determine the one or more characteristics of the acoustic noise produced by the first and second air pumps using a signal output from a microphone integrated in the monitor, or by using a signal output from the pressure transducer, or by using electrical currents from the air pumps.
27. The noninvasive blood pressure monitor of claim 1 , wherein the acoustic displeasure metric is further based on loudness or frequency content.
28. The noninvasive blood pressure monitor of claim 1 , wherein the acoustic displeasure metric is inversely related to the beat frequency.
29. The noninvasive blood pressure monitor of claim 28 , wherein the acoustic displeasure metric is based on the one or more characteristics of the acoustic noise produced by the first and second air pumps.
30. The noninvasive blood pressure monitor of claim 1 , wherein the controller is configured to adjust the one or more operating characteristics of the first and second air pumps so as to increase destructive interference in the acoustic noise produced by the first and second air pumps.