>210, 225, 210, to 235, mechanical CPR can be performed on patient 200.

In some cases, position 210, where the suction cup 145 engages the patient's torso 220, may be defined as a reference point or position. From this position 210, the compression and decompression stroke of the piston 140 can be determined. Defining and using reference position 210 as a position from which to measure the depth of CPR compressions and the height of CPR decompressions can help to avoid unintended injury to a patient. For example, a manual CPR device can be placed on a patient's torso and a user can manually push or pull on the manual CPR device to cause compressions or decompressions. However, the user of the manual CPR device does not have any reference position from which to measure the depth of compressions or the height of decompressions. Without a reference position, the user can cause additional injuries to the patient. For example, if the user pushes the manual CPR device down too far into the patient's chest during a compression, the compression might break one or more of the patient's ribs. When one or more of the patient's ribs are broken, it may be easier to compress the patient's chest and a subsequent compression by user of the manual CPR device can cause even more of the patient's ribs to be broken, and injury to the patient's internal organs. In contrast, establishing reference position 210 with respect to the patient's torso 220 can prevent CPR compressions from extending too deep. Moreover, even if one injury does occur (e.g., the breaking of a patient's rib), the reference position 230 will not change and the likelihood that a subsequent compression will cause even further injury can be reduced.

Using a reference position can also be beneficial is circumstances where the patient is not located in a stable or a flat position. For example, if a patient is being transported, such as on a stretcher or an ambulance, the patient may be jostled around or otherwise not in a stable position. However, if the mechanical CPR device is moving with the patient (e.g., if mechanical CPR is being performed in an ambulance while the patient is being transported), the reference position of the piston 140 or suction cup 145 can remain relatively fixed with respect to the patient and the mechanical CPR device can avoid over-compression and over-decompression. Thus, the benefits of avoiding unintended injury could still be realized if the patient is otherwise moving. In another example, the patient can be located in a position that is not flat, such as if the patient is being transported down stairs or the patient is on rough terrain. In these cases, if the mechanical CPR device is located with the patient in the same non-flat position, the reference position used by the mechanical CPR device would reflect the patient's non-flat position and the mechanical CPR device could avoid over-compression and over-decompression. A user performing manual CPR under such conditions may have difficulty in maintaining a desired compression depth and/or decompression height.

In some cases, the patient's torso may be of a smaller dimension, such that its maximum height is below position 210. This position is depicted in FIG. 3A as position 305. In this case, the piston 140 may not be of a sufficient length to extend to position 305 and extend further to compress the patient's torso 220. As depicted in FIG. 3B, the piston 140 may be modified by a device or mechanism 315 to extend the length of piston 140, so that the piston 140 may extend a distance 310 to engage a patient's torso 220 at position 305. In this way, by extending the piston 140 via device 315, the piston's reference point may be set correctly to accommodate a patient having a smaller sternum with a height 305. By adjusting the reference point of the piston 140/suction cup 145 to height 305, the movement of the piston may be recalibrated to correctly and safely perform mechanical CPR on patient 200.

FIG. 4 depicts a side view of a mechanical CPR device 100 with an adjustable length piston 140. By modifying piston 140 to include a length adjustment device 315, the piston 140 may be extended to position 305 from position 210. In some aspects, a change in the reference point or nominal height of the piston 140 from position 210 to position 305, represented by displacement 310, may be detected by one or more sensors. The change in height or displacement 310 of the reference point may then be communicated to a controller and/or drive component of the mechanical CPR device 100. The controller/drive component may adjust the movement of the piston based on the detected change 415 in position or displacement of the piston 140, for example, to calibrate the fully extended position and the retracted position of the piston 140 to safely perform mechanical CPR on a patent having a smaller torso/sternum.

FIGS. 5A, 5B, 5C, 5D, 5E, 5F, and 5G depict multiple views, both side and cut-out views, of an example 500 of an external piston spacer 555 that may be used to extend the length of piston of a mechanical CPR device, such as piston 140 of mechanical CPR device 100. In reference to FIG. 5A, a piston of a mechanical CPR device, for example piston 140, may include an external piston sleeve 505 and an inner piston 510 having an outward surface 512. A portion of the length of the inner piston 510 may be slidably located within the external piston sleeve 505. The amount or length by which the inner piston 510 is positioned within the external piston sleeve 505 may adjust a full piston length 522. An end of the piston 515, which in some cases may include a suction cup 145, may be positioned a distance 520 away from the end of the external piston sleeve 505. In some cases, the inner piston 510 may be biased to be located at least partially within the external piston sleeve 505. In some cases, a spring 545 or a member having elastic or semi-elastic properties may be located along a length 522 of the inner piston 510, for example inward from the outward facing surface 512. The spring may at least partially bias the inner piston 510 to slide partially into the external piston sleeve 505. In some cases, a drive component of the attached mechanical CPR device (not shown), such as mechanical CPR device 100, may bias or determine a resting position of the inner piston 510.

In some cases, the external piston spacer 555, the inner piston 510, and/or the external piston sleeve 505 may be defined by a circular or oval cross-section. In other cases, the external piston spacer 555, the inner piston 510, and/or the external piston sleeve 505 may be defined by other cross-sections, such as, rectangular, polygon, and so forth, such that the external piston spacer 555, the inner piston 510, and the external piston sleeve 505 have the same shaped-cross section (but not necessarily the same dimensions). In other examples, the external piston spacer 555, the inner piston 510, and/or the external piston sleeve 505 may have different-shaped cross-sections, that are engage-able or slidable about each other.

As depicted in FIG. 5B, the inner piston 510 may be extended 524 away from the external piston sleeve 505. In some cases, the length from the piston end and the end of the external piston sleeve 505 may be extended to a length 521, thus increasing the full piston length an equal amount to length 523. In this scenario, the outward surface 512 of the extended portion of the inner piston 510 (not within the external piston sleeve 505), may include one or more grooves or recesses 530. As depicted in FIG. 5B, one groove 530 may be disposed on the outward surface 512 of the inner piston 510. However, in other scenarios, the outward surface 512 of the inner piston 510 may have two opposed grooves 530, or any other number of grooves or recesses in any angular arrangement/at any position along the outward surface 512 of inner piston 510.

FIG. 5C depicts a cutout-view of piston having extended length 523. The inner piston 510 may include a center piston or center piston portion 535, for example, that may be connected to a drive component or motor of a mechanical CPR device, such as device 100. A slidable ring or inner sleeve 540 may be disposed about the center piston portion 535 at an end of the center piston portion 535 located distal to the external piston sleeve 505. The inner sleeve 540 may contact a spring 545, also positioned axially relative to the inner piston 510 and the inner piston portion 535, between the sleeve 540/center piston portion 535 and the piston end 515. In some cases, the spring 545 may bias the inner piston 510 and/or the center piston portion 535 to move towards the external piston sleeve 505. In yet some examples, the spring 545, additionally or alternatively, may aid in determining and setting the correct compression and decompressions stroke of piston 140, for example via sensing force exerted on the piston end 515. In some examples, a drive component of the mechanical CRP device, and/or one or more other springs may bias the center piston portion 535/ring 540 to contact spring 545. In some examples, the one or more grooves 530 may extend through a thickness of the outward surface 512, such that a portion of the center piston portion 535 and/or the piston ring 540 are exposed.

A removable external piston spacer 555, as depicted in FIG. 5D, having a circular cross-section, may include two flanges or ridges 560, 565. The two flanges 560, 565, may be located on an inward facing surface of the external piston spacer 555. In some cases, the external piston spacer 555 may be ring-shaped in cross-section, having a thickness. In this scenario, the external piston spacer 555 may engage at least a portion of the inner piston 510, for example, when the flanges 560,565 are aligned with grooves 530. In some examples, the flanges 560, 565 may have a substantially rectangular shape to engage and fit within grooves 530. In other cases, the flanges 560, 565 and the grooves 530 may have other corresponding shapes, such as circular, triangular, polygon shape, etc. In some cases, the flanges 560, 565 may extend inward from the external piston spacer 555 a distance. The distance may be equal to or greater than a thickness of the outward surface 512 of the inner piston 510, so as to ensure stable engagement with the inner piston 510.

As depicted in FIG. 5E, the external piston spacer 555 may be placed on the outward surface 512 of the inner piston 510, by aligning the flanges 560, 565 with the grooves 530. In some cases, inserting the flanges 560, 565 into the grooves 530 may push or force 570 the center piston portion 535 and/or the ring 540 upward toward the external piston sleeve 505. In some examples, the flanges 560, 565 may extend inward from the external piston spacer 555 a distance greater than a thickness of the outer surface 512 of the inner piston 510, such that the flanges 560, 565 may separate the center piston portion 535 and/or the ring 540 from contacting the spring 545, as depicted in FIG. 5F. One or more sensors 570, such as a wiper, potentiometer, or other sensor electrical, mechanical, or optical sensor may detect the change in length 523 of the piston 140 caused by the presence of the external piston spacer 555. The sensor(s) 570 may communicate the detected change in position or displacement to a controller or drive component of the mechanical CPR device 100. The controller or drive component may then modify the compression and decompression stroke, e.g., the oscillation of the piston 140 to accommodate the changed length. Modifying the movement of the piston 140 may ensure or help to ensure more safe operation of the mechanical CPR device 100 when a patient having a smaller sternum/torso is treated using the mechanical CPR device 100.

In some examples, the one or more sensors 570 may be part of the drive component or motor of the mechanical CPR device 100. In this scenario, the sensor(s) 570 may be wipers that detect the angular position of the motor or drive component, for example of a drive shaft of a motor. The drive component may be configured, for example via instructions such as computer code and the like, to adjust at least one of a stroke compression and stroke decompression based on the detected change in resting angular position of the drive shaft.

In the example illustrated, the flanges 560 and 565 may be spaced at 180 degrees apart from one another, each positioned at an external edge of the external piston spacer 555. In this example, the external piston spacer 555 may also wrap approximately 180 degrees or less around the inner piston 510.

In some examples, the external piston spacer may have a length that is less than the length of the inner piston 510, so as to be engage-able about the outward face 512. In the example illustrated, the flanges 560, 565 may prevent the inner piston 510 from sliding, at least partially, into the external piston sleeve 505, for example by opposing a bias created by spring 545, a drive component, or any number of spring or elastic members. In other examples, a body of the external piston spacer 555 may prevent the inner piston 510 from sliding, at least partially, into the external piston sleeve 505.

FIGS. 6A, 6B, 6C, 6D, and 6E depict multiple views, both side and cut-out views, of an example 600 of an internal bayonet sleeve 620 that may be used to extend the length of a piston of a mechanical CPR device, such as piston 140 of mechanical CPR device 100. In the example descried below, the piston, such as piston 140, may include an external piston sleeve 505, and an inner piston 510 having a piston end 515, as described above in reference to FIG. 5.

The inner piston 510 may include a center piston 615, which may include one or more aspects of center piston portion 535 described above. The center piston 615 may be axially positioned relative to the external piston sleeve 505. The center piston 615 may contact a compression spring 605 at one end proximate to the piston end 515 and may contact a decompression spring 610 at an opposing end proximate to the external piston sleeve 505. The compression spring 605 and/or the decompression spring 610 may bias the center piston 615 to at least partially slide into the external piston sleeve 505. In some cases, the compression spring 605 may detect a force applied between the piston end 515, for example against a patient, and the center piston 615. The compression of the spring 605 may inform a controller or drive mechanism of the mechanical CPR device 100 when a fully compressed position has been reached. Similarly, the decompression spring 610 may detect a force applied between the center piston 615 and the external piston sleeve 505. The decompression of the spring 610 may inform a controller or drive mechanism of the mechanical CPR device 100 when a fully decompressed position has been reached. The center piston 615 and/or the inner piston 510 may be rotatably connected to a mechanical CPR device (not shown), such as device 100, by a retaining ring 640. In some cases, the center piston 615 may be connected to and driven by a drive shaft or other drive component of the mechanical CPR device 100. The drive component may drive the center piston 615 to extend away from and retract toward the CPR device 100 and the external piston sleeve 505.

An internal bayonet sleeve 620 may slidably surround or engage a portion of an outside surface 616 of the center piston 615. The internal bayonet sleeve 620 may form a ring or partial ring around the center piston 615. The bayonet sleeve 620 may have a length 621 and may have a plurality of grooves 625, 630 on one end. The plurality of grooves 625, 630 may be located at different angular positions around the bayonet sleeve 620 and may have varying lengths relative to length 621 of the bayonet sleeve 620. For example, groove 625 may only define a space having a short length, while groove 630 may define a space having a length equal to length 621 of the bayonet sleeve 620. Any number of grooves 625, 630 having varying lengths may similarly define spaces on bayonet sleeve 620.

One or more locking rods 635 may be positioned on the outside surface 616 of the center piston 615. The locking rod(s) 635 may have any number of shapes, such as circular, rectangular, polygon, etc., and may extend beyond the outside surface 616 a distance. The distance may be short enough to allow the center piston 615 and the locking rods 635 to rotate 645 relative to the outward surface 512 and/or the internal bayonet sleeve 620. In some cases, the one or more locking rods 635 may be connected to the outward surface 512, such that rotating the inner piston 510 may rotate the center piston 615.

The one or more locking rods 635 may have a width that is similar to or slightly smaller than a width of grooves 625, 630 of the internal bayonet sleeve 620, such that the locking rod(s) 635 may engage one or more grooves 625, 630. When one or more locking rods 635 engage one or more grooves 625, 630, the center piston 615 may be locked or rotationally fixed relative to the internal bayonet sleeve 620 and/or the outward surface or plate 512.

As depicted in FIG. 6C, the inner piston 510 and/or center piston 615 may be extended 650 away from the external piston sleeve 505, for example, by applying a force to piston end 515 and/or inner piston 510. Extending the center piston 615 relative to the internal bayonet sleeve 620, which may be fixed to the external piston sleeve 505, may disengage the one or more locking rods 635 from one or more of the grooves 625, 630. In one example, two locking rods 635 may be positioned on the center piston 615, 180 degrees apart from each other. Similarly, two grooves 625, having the same length, may also be positioned on the internal bayonet sleeve 180 degrees apart. By extending the center piston 615 away from the internal bayonet sleeve 620 and disengaging the locking rods 635 from grooves 625, the center piston 615 may be made rotatable about the internal bayonet sleeve 620. As depicted in FIG. 6D, the center piston 615 may be rotated 90 degrees clockwise 655 relative to the bayonet sleeve 620. The locking rods 635 may be aligned with grooves 630 (in this example, also spaced 180 degrees apart and having a same length). As depicted in FIG. 6E, once aligned, the center piston 615 may be moved or pushed 660 toward the external piston sleeve 505 until the locking rods 635 engage or stop against an end of grooves 630 or at the decompression spring 610, or until the internal bayonet sleeve 620 contacts the spring 605. In some cases, one or more of springs 605, 610 may bias the center piston 615 to naturally rest at a position closest to the external piston sleeve 505.

In some cases, one or more sensors 665 may be positioned on the outer piston 505 to detect a change in the length of the inner piston 510/the entire piston 140 (including the inner piston 510 and the external piston sleeve 505), caused by positioning the locking rods 635 in different grooves 625, 630. In some cases, the one or more sensors 665 may include an n electrical sensor, such as a wiper or potentiometer, a mechanical sensor, and/or an optical sensors. In some cases, the one or more sensors 665 may detect a position of the inner piston 510 relative to the external piston sleeve 505, may detect the angular position of a drive component of the mechanical CPR device 100, and/or may detect contact between the locking rods 635 and one or more grooves 625, 630. In some examples, each contact position between a groove 625, 630 and a locking rod 635 may be associated with a predetermined or pre-measured distance or displacement. Upon detection by sensor(s) 665, the corresponding displacement value may be accessed and used to calibrate a controller or drive component of the mechanical CPR device.

FIG. 7 depicts an example of an adjustable piston including a piston adapter 700. The piston adapter 700 may be removably attachable to a surface 750 of piston, such as piston 140 attached to a mechanical CPR device 100. In some cases the piston adapter 700 may be attachable to the bottom surface of suction cup 145. The piston adapter 700 may include a piston connection surface 715 connected to one end 721 of a body 720, which may be circular in cross section. At an opposite end of the body 720, a suction cup 705 may be attached and configured, for example, to contact the torso/sternum of a patient. In some cases, suction cup 705 may be similar to and/or include one or more aspects of suction cup 145. In some aspects, the piston connection surface 715 or plate may be connected to the suction cup 705 via one or more members 730, 735, which may add rigidity to the piston adapter 700.

To attach the piston adapter 700 to the piston 140, the piston adapter 700 may be positioned beneath the piston surface 750 and the piston connection surface 715 may be moved to contact the piston surface 715. Upon contact, a gas check valve 725 may be engaged to temporarily or removably adhere the piston connection surface 715 to the piston surface 750. In some examples, the piston surface 750 or other part of piston 140 may include one or more sensors 755. The one or more sensors 755 may detect when the surfaces 750 and 715 come into contact. The one or more sensors 755 may include any of pressure sensors, optical sensors, force sensors, etc. In some aspects, upon detecting contact between surfaces 750 and 715, the piston 140 or a controller thereof may send an indication (e.g., via a wireless connection by a transceiver, a wired connection, etc.) to the piston adapter 700. Upon receiving the indication, the gas check valve 725 may be made operational. A controller of the piston 140 may detect when the piston adapter 700 is attached to the piston 140, and may prevent attachment of the piston adapter 700 to the piston 140 until the piston controller has detected and acknowledged, for example, the change in length of piston 140 due to the attachment of the piston adapter 700. In this way, injury to a patient may be reduced or eliminated that may be caused by the piston 140 being extended toward a patient without proper calibration (e.g., accounting for the length added by the piston adapter 700).

In some cases, a length of the piston adapter may be detected by the piston/sensor 755 or communicated to the piston controller by the piston adapter 700. The piston controller may then adjust a stroke of the piston 140 to account for the changed length of the piston 140.

FIG. 8 depicts an example of a method 800 of configuring a mechanical CPR device, such as device 100, to accommodate a patient, for example having a smaller torso/sternum. At block 805, a height of a patient to be treated may be detected. This may include using one or more sensors. In some cases, a piston, such as piston 140, may be extended toward a patient until contact with the patient is detected, for example, by analyzing the force exerted on one or more springs of the piston 140, such as spring 545 and/or 605. In other cases, one or more optical sensors may be used to detect the height of a patient. In yet some aspects, the height may be received by the mechanical CPR device 100, for example from one or more inputs via an operator.

At block 810, a reference point of the piston 140 may be adjusted based on the detected height of the patient. In some cases, the reference point may be adjusted and/or set according to the techniques described in reference to FIGS. 3A and 3B, for example to height 305 from height 210, which may be a nominal height of the mechanical CPR device 100/piston 140.

In some cases, method 800 may include operations performed at block 815, including adjusting a length of the piston to contact the patient, for example according to the adjusted reference point. The operations at block 815 may be performed by placing an external piston spacer 500 on the piston, as described in reference to FIGS. 5A through 5G, at block 816. The operation at block 815 may additionally or alternatively include adjusting an internal bayonet sleeve 600/one or more locking rods engage-able about the bayonet sleeve, as described above in reference to FIGS. 6A though 6E, at block 817. The operation at block 815 may additionally or alternatively include attaching a removable piston adapter 700 to the end of the piston, as described above in reference to FIG. 7.

At block 820, the stroke of the piston may be determined based on the adjusted reference position. Mechanical CPR may then be performed on a patient using the configured mechanical CPR device according to the determined stroke of the piston. In this way, compression and decompression of the piston may be calibrated to account for the added piston length. This may increase the number of patients that may be treated by a mechanical CPR device 100. Additionally or alternatively, the use of an adjustable piston may help reduce risk associated with mechanical CPR, including injury to a patient due to the compression stroke of the piston not being adjusted to a patient having a smaller torso.

FIGS. 9A and 9B show a cross-section view of another example of a mechanical CPR device with an adjustable length, or telescoping, piston. FIG. 9A illustrates the adjustable piston 904 in its most retracted position and FIG. 9B illustrates the adjustable piston 904 in its most extended position. The mechanical CPR device includes a main portion, also referred to herein as a central unit 900. A compression device 902 is housed within the central unit 900. The compression device 902 includes an adjustable piston 904 that can extend from the central unit 900 toward a patient. The adjustable piston 904 can be manually extended in length to adjust to different chest of heights of patients. When set to a desired height, the adjustable piston 904 can then be extended and retracted by the compression device 902.

The adjustable piston 904 can include an outer piston sleeve 906, which is connected to the compression device 902 and an inner piston sleeve 908 that can move relative to the outer sleeve 906 in the direction of arrow 910. In FIGS. 9A and 9B, the compression device includes a motor 912 attached to a ball screw shaft 914, which is attached to the outer sleeve 906. Rotation of the motor 912 causes the adjustable piston 904 to extend toward and retract from the patient in the direction of arrow 910 which is along axis 924. While a motor 912 and ball screw shaft 914 are illustrated in FIG. 9, any linear motion actuator may be used as the compression device 902.

The adjustable piston 904 can be locked at a particular length by locking the outer sleeve 906 to the inner sleeve 908. The adjustable piston 904 may include an internal locking mechanism, including a pin or ball bearing, as shown in FIGS. 10 and 11. The adjustable piston 904 can include a locking mechanism 916, such as a handle or grip, for locking the outer sleeve 906 and inner sleeve 908 in a position or unlocking the inner sleeve 908 relative to the outer sleeve 906 to set a desired position of the inner sleeve 908 relative to the outer sleeve 906. The locking mechanism 916 may be permanently affixed to the inner sleeve 908 and cause rotation of the inner sleeve 908 to lock or unlock the inner sleeve 908 relative to the outer sleeve 906.

An end of the adjustable piston 904 may contain a suction cup 918 to temporarily attach to a patient. However, in some examples, instead of suction cup 918, an adhesive pad may be provided or the end of the adjustable piston 904 may be flat and not temporarily attach to the patient.

The adjustable piston 904 can be extended along the axis 924 to a length that is approximately double the height of the central unit 900. That is, since the adjustable piston 904 is telescoping, almost the entire outer sleeve 906 can be extended out from the central unit 900 until near the end of the screw shaft 914. Enough distance needs to be left on the screw shaft 914 to provide a compression to the patient once the adjustable piston 904 is touching or attached to the chest of the patient. The inner sleeve 908 can extend to a length that is approximately the length of the outer sleeve 906, as illustrated in FIG. 9B.

While FIGS. 9A and 9B show the adjustable piston 904 in its most retracted position and most extended position, as will be understood by one skilled in the art, the adjustable piston 904 can be set at any length in between. When the desired position of the adjustable piston 904 has been reached, the locking mechanism 916 can be rotated to the locked position and the motor 912 can perform compressions to extend and retract the adjustable piston 904 by rotating the screw shaft 914.

The compression device 902 may also include one or more distance sensors in some examples. In the example of FIGS. 9A and 9B, a distance radar sensor 920 and a distance laser sensor 922 are included. However, examples of the disclosure do not require both sensors and/or these particular types of sensors. Any type of sensor that can measure a distance may be used.

In the examples of FIGS. 9A and 9B, the distance radar sensor 920 can measure the distance from a bottom surface of the compression device 902 to the patient. The distance laser sensor 922 can measure the distance from the bottom surface of the compression device 902 to the suction cup 918, if attached. The outputs of the sensors 920 and/or 922 can be sent to a controller to determine the stroke of the piston based on the adjusted length of the adjustable piston 904, similar to block 820 in FIG. 8.

FIG. 10 is cross-section cut away view of the adjustable piston 904 illustrating a pin bearing locking mechanism. For example, the outer sleeve 906 may include a number of cavities 1002 on an inner surface to receive a spring-loaded pin 1004 on the outer surface of the inner sleeve 908. The inner sleeve 908 can be rotated relative to the outer sleeve 906 to push the spring-loaded pin 1004 inward against the spring (not shown). The inner surface of the outer sleeve 906 can include portions without cavities 1002 which can allow the inner sleeve 908 to move relative to the outer sleeve 906. When the inner sleeve 908 is in the desired position, the inner sleeve can be rotated until the spring-loaded pin 1004 engages with a cavity in the outer sleeve 906.

FIG. 11 is a cross-section view of the adjustable piston 904 having a ball bearing locking mechanism. In this example, the outer sleeve 906 includes cavities 1102 or indents which can be received by a ball 1104. The inner sleeve 908 can be pushed up and twisted so that the ball 1104 is received in the cavity 1106, which releases the inner sleeve 908 from the outer sleeve 906. The inner sleeve 908 can be positioned as desired and then the inner sleeve 908 can be rotated and locked so that the ball 1104 is received at the cavity 1102 closest to the desired position.

While a pin bearing and ball bearing locking mechanism are shown in FIGS. 10 and 11, examples of the disclosure may use any locking mechanism that can set a height between the outer sleeve 906 and the inner sleeve 908. The adjustable piston 904 is able to extend from the central unit 900 to almost or approximately double the height of the central unit 900 to be able to accommodate more patient sizes in the compression device 100.

FIGS. 12A and 12B illustrate a cross-section view of another example of an adjustable length compression device. For ease of illustration, FIGS. 12A and 12B only illustrate the compression component of the compression device, but as will be understood by one skilled in the art, the example illustrated in FIGS. 12A and 12B can be used in the main portion 115 of the compression device 100. FIG. 12A illustrates a fully retracted compression device 1200 and FIG. 12B illustrates a fully extended compression device 1200.

The compression device 1200 includes a two-stage telescopic linear piston that can extended longer than the height of the compression device 1200. The compression device 1200 can include a central housing 1202, a motor 1204, such as a frameless brushless torque motor, which includes a fixed outer stator 1206 and a hollow rotor 1208. The rotor 1208 can have axial splines on the inner surface which can engage and transfer torque to a cylinder 1210, also referred to as a compression housing, that has similar splines along the outer surface (not shown). This can allow torque to be transferred from the rotor 1208 to the cylinder 1210 independent of the axial position of the cylinder 1210.

The central housing 1202 is fixed to the stator 1206 and includes threads 1212 on an inner surface that engage with threads 1214 on an outer surface of cylinder 1210. The threads 1214 on the outer surface of cylinder 1210 do not need to be on the entire outer surface. As seen in FIGS. 12A and 12B, the cylinder 1210 may include a protrusion or lip 1216 on the top which includes the threads 1214.

The cylinder 1210 also includes threads 1218 on an inner surface that are in contact with corresponding threads 1220 on an outer surface of a plunger 1222. The plunger 1222 is connected to an inner cylinder 1224, also referred to as a piston, which has an external pressure pad 1226. As will be understood by one skilled in the art, the end of the piston could have a suction cup in other examples, or a suction cup could attach to the pressure pad 1226.

The plunger 1222 is also in contact with sleeve 1228 and a center rod 1230. The sleeve 1228 can slide axially on the center rod 1230 and in the plunger 1222. The center rod is fixed to the central housing 1202. The cross-section of the sleeve 1228 and the center rod 1230 are non-circular to prevent the plunger 1222 from rotating when the cylinder 1210 is rotating.

The thread 1218 on the inner surface of the cylinder 1210 is an opposite direction of the thread 1212 on the inside of the central housing 1202. When the rotor 1208 rotates, the cylinder 1210 will also rotate and move up or down with respect to the stator 1206 by means of the threads 1214 of the central housing 1202. In the same rotation, the inner cylinder 1224 will also move up or down with respect to the cylinder 1210 by means of the threads 1218. Therefore, the rotation of the rotor 1208 is converted to a linear motion of the inner cylinder 1224 and the pressure pad 1226 when it compresses a patient. The cylinder 1210 also moves axially. The total movement of the external pressure pad 1226 is within the range of approximately 100% to 200% of the height of compression device 1200.

During operation, a user can select to set a height of the compression device 1200 according to a chest height of the patient. A user may manually set the height, such as by pressing a button (not shown) to rotate the motor 1204 in a first direction to retract the pressure pad 1226 or a second direction to extend the pressure pad 1226. When the pressure pad 1226 is at the desired position, compressions can begin. In some examples, the user may operate the compression device 1200 by a remote device and the instructions are received wirelessly by a controller (not shown) in the compression device 1200.

In an alternative example, the pressure pad 1226 may include a sensor. A user may select a mode to automatically set a height of the compression device 1200. A controller may instruct the motor 1204 to rotate until the sensor on the pressure pad 1226 indicates the pressure pad is in contact and/or attached to a chest of a patient. The height of the compression device 1200 can be recorded and used to begin compressions, similar to block 820 in FIG. 8.

FIG. 13 illustrates a cut-away view of an alternative adjustable length compression device. For ease of illustration, FIG. 13 only illustrate the compression component of the compression device, but as will be understood by one skilled in the art, the example illustrated in FIGS. 12A and 12B can be used in the main portion 115 of the compression device 100.

The compression device 1300 includes a two-stage telescopic linear piston that can extended longer than the height of the compression device 1300. The compression device 1300 can include an outer housing 1302 that would be stored in the main portion 115, a motor that includes a fixed outer stator 1304 and a hollow rotor connected to a large diameter hollow ball nut 1308. In FIG. 13, the rotor and ball nut 1308 are shown as one component, but as will be understood by one skilled in the art, two separate components may be provided. The rotor and ball nut 1308 rotate around a hollow spindle or screw 1310 causing the screw 130 to extend outwards relative to the outer housing 1302. The rotation of the rotor and ball nut 1308 create a linear motion of the spindle 1310 relative to the outer housing 1302 and along an arrow 1312.

A piston 1314 fits within the hollow spindle 1310 and the piston 1314 has an end portion 1316 which can attach to or touch a patient's chest, or can have a suction cup or other device attached. The piston 1314 is connected to the outer housing 1302 by a spur gear 1318 and pinion 1320 mechanism.

The linear movement of the spindle 1310 also causes the spur gears 1318 to turn and can extend the piston relative to the spindle 1310. This results in a simultaneous telescopic extension of the piston 1314 with respect to the spindle 1310 and the spindle 1310 relative to the outer housing 1302.

The rotor and hollow ball nut 1308 can rotate to extend the length of the compression device 1300 until the end portion 1316 attaches to or touches as patient. The compression device 1300 can rotate the rotor and hollow ball nut 1308 to extend and retract the spindle 1310 and piston 1314 toward the patient along arrow 1312 to provide compressions. The total movement end portion 1316 is within the range of approximately 100% to 200% of the height of outer housing 1302.

As will be understood by one skilled in the art, a controller can instruct the rotor and hollow ball nut 1308 to rotate to cause the compression device 1300 to either extend to a desired height and/or to provide compressions. Although not shown, the compression device 1300 can also include a sensor for detecting the height and that information can be used to for performing compressions, similar to block 820 in FIG. 8.

FIG. 14 illustrates another example of an adjustable length compression device. For ease of illustration again, only the compression component is illustrated in FIG. 14. However, as will be understood by one of ordinary skill in the art, central housing 1400 can be used in place of main portion 1115 in FIG. 1. A central housing 1400 can include a number of additional components not discussed in detail below, such as a battery 1402 and electronic circuitry 1404. The central housing 1400 has an axis 1406 extending toward a patient.

In this example, a compression mechanism 1408 is disposed in the central housing 1400. The compression mechanism 1408 can move relative to the central housing 1400 along the axis 1406. That is, the compression mechanism 1408 can extend and retract toward a patient by a driving component.

In some examples the driving component can be a worm drive to translate the compression mechanism 1408 along the axis 1406. One or more worms 1410 are provided in the central housing 1400. Worm gears 1412 are provided at the top portion of the compression mechanism 1408. The worm gears 1412 can be connected with a timing belt, illustrated in FIG. 15 and discussed below. A motor 1414, such as a planetary gear motor, is provided to rotate at least one of the worm gears 1412. As the worm gears 1412 rotate, they can move along the worms 1410 to move the compression mechanism along the axis 1406.

A piston 1416 can be extended and retracted from the compression mechanism 1408. A piston driving component can be included within the compression mechanism 1408, as shown in FIG. 14, to move the piston 1416 along the axis 1406 toward and away from the patient. In this example, the driving component moves along the axis 1406 with the compression mechanism 1408.

The piston 1416 can move separate from the compression mechanism 1408 along the axis 1406 to extend and retract from within the compression mechanism 1408 by the piston driving component. In some examples, the piston driving component could be located in the central housing 1400. In such examples, the driving component would not move with the compression mechanism 1408 but would be fixed to the central housing 1400.

The piston driving component is a linear actuator that can cause the piston to extend and retract from the compression mechanism 1408 toward and away from a patient. In the example shown in FIG. 14, the piston driving component includes a motor 1418 and the piston 1416 is attached to a ball bearing 1420 that moves up and down a screw shaft 1422 as the motor 1418 rotates the screw shaft 1422. However, as will be understood by one of ordinary skill in the art, other linear actuators may be used for the piston driving component. The piston 1416 includes an end portion 1424 which may have a suction cup attached or any other type of pad to provide compressions to a patient.

FIG. 15 illustrates a perspective view of the compression mechanism 1408 and the worms 1410. As can be seen in FIG. 15, the compression mechanism 1408 can include a number of worm gears 1412 that interact with worms 1410 in the central housing 1400. A timing belt 1500 is attached to each of the worm gears 1412, which can ensure straight movement up and down so that the worm gears 1412 are rotating at the same rate by the motor 1415. The entire compression mechanism 1408 can extend and retract within the central housing 1400 by the worm drive. While a worm drive is illustrated in FIGS. 14 and 15, any type of linear actuator may be used to move the compression mechanism 1408 along the axis 1406. For example, ball screws may be used in place of the worm drive. Rather than worms 1410, one or more screw shafts could be provided and the compression mechanism 1408 could be attached to ball bearings that move along the screw shafts. A timing belt may still be provided to ensure the ball bearings rotate at the same speed if multiple screw shafts are used.

Using the example of FIGS. 14 and 15, the compression mechanism 1408 can extend from the central housing 1400. Further, the piston 1416 can then extend from the compression mechanism 1408. When used in place of the main portion 115 of FIG. 1, the compression mechanism 1408 can be extended toward a patient until the end portion 1424 touches or attaches to a patient. If the full extension of the compression mechanism 1408 is not long enough, then the piston 1416 can be further extended until the end portion 1424 is touching or attached to a patient. The piston driving component can then extend and retract the piston 1416 to provide compressions.

Similar to the example of FIGS. 12A and 12B, during operation, a user can select to set a height of the compression device according to a chest height of the patient. A user may manually set the height, such as by pressing a button to cause one or both of the driving components to cause the compression mechanism 1408 and/or the piston 1416 to extend or retract. In some examples, the compression mechanism 1408 may move first until at the fully extended position. In other examples, the compression mechanism 1408 and the piston 1416 may move in coordination. When the end portion 1424 is at the desired position, compressions can begin.

In an alternative example, the end portion 1424 may include a sensor. A user may select a mode to automatically set a height of the compression device. A controller in the electronic circuitry 1404 may instruct one or both of the driving components to move the compression mechanism 1408 and/or the piston 1415. The height of the compression device can be recorded and used to begin compressions.

FIG. 16 is another example of an adjustable length compression device that can be used in place of main portion 116 in FIG. 1. A central housing 1600 can include a number of additional components not discussed in detail below, such as a battery and electronic circuitry. The central housing has an axis 1602 extending toward a patient.

In this example, a compression mechanism 1604 is disposed in the central housing 1600. The compression mechanism 1604 can move relative to the central housing 1600 along the axis 1602. That is, the compression mechanism 1604 can extend and retract toward a patient by a driving component.

In this example, the driving component includes two screw shafts 1606 in the central housing 1600 attached to the compression mechanism 1604 by two ball bearings 1608. A motor 1610 causes the ball bearings 1608 to rotate to move the compression mechanism 1604 along the axis 1602.

A piston 1612 can be extended and retracted from the compression mechanism 1604. In this example, the piston is attached to a screw shaft 1614 by a ball bearing 1616. The motor 1610 also rotates the ball bearing 1616 when rotating ball bearings 1608 which causes the compression mechanism 1604 and the piston 1612 to extend and retract at the same time. Ball bearings 1608 and 1616 may be attached by a timing belt 1622. Although not shown, as will be readily understood by one skilled in the art, a second motor could be provided to drive the ball bearings 1608 separately from the ball bearing 1616. In such an example, a timing belt may be provided to ensure that the ball bearings 1616 are rotating at the same speed.

In this example, the piston 1612 may include a telescoping portion 1618 that can be manually extended from the piston 1612 to provide even greater length to the compression mechanism 1604. The telescoping portion 1618 can be manually extended using any known technique, including, but not limited to, those discussed above in FIGS. 10 and 11.

During operation, the motor 1610 rotates until a suction cup 1620 or any other end portion of the piston 1612 touches or attaches to a patient. The motor 1610 can then extend and retract both the compression mechanism 1604 and the piston 1612 in conjunction to provide compressions.

FIG. 17 is another example of a compression mechanism 1700 that can be located in main portion 115 of FIG. 1. For each of illustration, the main portion 115, or a central housing, is not shown in FIG. 17. A central housing can include a number of additional components not discussed in detail below, such as a battery and electronic circuitry.

The compression mechanism 1700 includes a cover