Patent Description:
IO access can be acquired in as little as <NUM>-<NUM> seconds with a relatively high chance of success. The commercial state-of-the-art medical device for IO access is a small, drill-like device built around a relatively primitive electric motor. Motors such as the foregoing provide an adequate means for drilling to effectuate IO access, but such motors are not necessarily tuned to the needs of IO access. The infrastructure of such motors (e.g., batteries, wires, gear trains, gear-reduction hardware, switches, etc.) is largely overbuilt for just <NUM>-<NUM> seconds of drilling. Additionally, the drill-like device and the motors thereof must be monitored and managed by clinical personnel for readiness, and there are requirements and regulations related to the disposal of the foregoing medical devices. What is needed is needed is a better tuned medical device that significantly reduces design and manufacturing complexity while optimizing user experience. <CIT> relates to a device for surgery, and more particularly, for accessing bone marrow for enhancement of tissue repair. <CIT> relates to drilling devices, and more particularly to medical drilling devices, such as which may be used, for example, for drilling into bone. <CIT> discloses an interosseous access device of the prior art.

Disclosed herein are constant-torque IO access devices and exemplary methods thereof that address the forgoing shortcomings.

Claim <NUM> defines the invention and dependent claims disclose embodiments. No surgical methods are claimed. Disclosed herein is an IO access device including, in some embodiments, a constant-torque spring assembly disposed in a housing, a drive shaft extending from the housing, and an IO needle coupled to the drive shaft. The drive shaft is coupled to the constant-torque spring assembly. The IO needle is configured to provide IO access to a medullary cavity of a patient.

The constant-torque spring assembly includes a metal ribbon reversely wound onto an output spool. The metal ribbon is configured to wind onto a storage spool with a constant torque when the output spool is released.

Spindles of the output spool and the storage spool are coupled together by at least one elastomeric loop to prevent any timing-related errors between the output spool and the storage spool.

In some embodiments, the housing includes a set of housing teeth around an aperture of the housing from which the drive shaft extends. The drive shaft includes a set of complementary drive-shaft teeth around the drive shaft opposing the set of housing teeth. The set of housing teeth and the set of drive-shaft teeth engage in an inactive state of the IO access device by a compression spring between a back side of the set of drive-shaft teeth and the output spool.

In some embodiments, the drive shaft is slideably disposed in an axial channel of the output spool such that force applied to a distal end of the IO needle simultaneously compresses the compression spring and inserts the drive shaft deeper into the axial channel. This disengages the set of drive-shaft teeth from the set of housing teeth and initiates an active state of the IO access device. In the active state of the IO access device, rotation of the IO needle is effectuated by the output spool of the constant-torque spring assembly on the drive shaft.

In some embodiments, a combination of a molded piece within the housing and an extension pin disposed in the axial channel of the output spool between the drive shaft and the molded piece is configured to stop over insertion of the drive shaft into the axial channel of the output spool. In addition, the combination of the extension pin and the molded piece is configured to decouple the force applied to the distal end of the IO needle from the constant-torque spring assembly.

In some embodiments, the compression spring is configured to relax when the force applied to the distal end of the IO needle is removed. This reengages the set of drive-shaft teeth with the set of housing teeth and reinitiates the inactive state of the IO access device.

In some embodiments, the IO access device is configured such that entry of the IO needle into the medullary cavity of the patient automatically removes the force applied to the distal end of the IO needle.

In some embodiments, the IO access device further includes an interlock including a trigger and a lock pin disposed between the trigger and the output spool in the inactive state of the IO access device. The trigger is configured to release the lock pin allowing the force applied to the distal end of the IO needle to simultaneously compress the compression spring and insert the drive shaft deeper into the axial channel.

In some embodiments, the IO access device further includes a braking system configured to act on the output spool to slow the metal ribbon from winding onto the storage spool.

In some embodiments, the IO needle is configured to separate from the IO access device subsequent to achieving IO access to the medullary cavity of the patient.

In some embodiments, the IO needle includes an obturator removably disposed in a cannula. The cannular has a lumen configured for at least interosseous infusion upon removal of the obturator.

Also disclosed herein as an example is an IO access device including, in some embodiments, a constant-torque spring assembly disposed in a housing, a drive shaft extending from the housing, and an IO needle coupled to the drive shaft configured to provide IO access to a medullary cavity of a patient. The constant-torque spring assembly includes a metal ribbon reversely wound onto an output spool. The metal ribbon is configured to wind onto a storage spool from the output spool with a constant torque in an active state of the IO access device. The drive shaft is slideably disposed in an axial channel of the output spool. Force applied to a distal-end portion of the drive shaft simultaneously compresses a compression spring and inserts the drive shaft deeper into the axial channel. This disengages a set of drive-shaft teeth around the drive shaft from an opposing set of housing teeth around an aperture of the housing from which the drive shaft extends and initiates the active state of the IO access device. The IO needle is configured to rotate in the active state of the IO access device and provide IO access to a medullary cavity of a patient by way of drilling with the IO needle.

In some examples, a combination of a molded piece within the housing and an extension pin disposed in the axial channel of the output spool between the drive shaft and the molded piece is configured to stop over insertion of the drive shaft into the axial channel of the output spool. In addition, the combination of the extension pin and the molded piece is configured to decouple the force applied to the distal-end portion of the drive shaft from the constant-torque spring assembly.

In some examples, the compression spring is configured to relax when the force applied to the distal-end portion of the drive shaft is removed. This reengages the set of drive-shaft teeth with the set of housing teeth and reinitiates the inactive state of the IO access device.

In some examples, the IO access device is configured such that entry of the IO needle into the medullary cavity of the patient automatically removes the force applied to the distal-portion of the drive shaft.

Also disclosed herein as an example is a method of an IO access device including, in some embodiments, an obtaining step of obtaining the IO access device. The IO access device includes a constant-torque spring assembly disposed in a housing, a drive shaft coupled to the constant-torque spring assembly and extending from the housing, and an IO needle coupled to the drive shaft. The method also includes an inserting step of inserting a distal end of the IO needle through skin at an insertion site of a patient. The method also includes an applying step of applying force to bone at the insertion site with the distal end of the IO needle. The applying step starts winding a metal ribbon of the constant-torque spring assembly from an output spool onto a storage spool, thereby starting rotation of the IO needle. The method also includes a drilling step of drilling through the bone until the IO needle enters a medullary cavity of the patient, thereby achieving IO access to the medullary cavity of the patient with the IO access device.

In some examples, the applying step inserts the drive shaft deeper into an axial channel of the output spool of the constant-torque spring assembly. The applying step also compresses a compression spring between a back side of a set of drive-shaft teeth around the drive shaft and the output spool. The applying step also disengages the set of drive-shaft teeth from an opposing set of housing teeth around an aperture of the housing from which the drive shaft extends to start the rotation of the IO needle.

In some examples, the method further includes a ceasing step of ceasing to apply the force to the bone with the distal end of the IO needle. The ceasing step removes at least a portion of the drive shaft from the axial channel of the output spool, relaxes the compression spring, and reengages the set of drive-shaft teeth with the set of housing teeth to stop the rotation of the IO needle.

In some examples, the ceasing step is manually initiated by a clinician after feeling a change in tissue density upon entering the medullary cavity of the patient.

In some examples, the ceasing step is automatically initiated by the IO access device after experiencing a change in tissue density upon entering the medullary cavity of the patient.

In some examples, the method further includes a triggering step of triggering a trigger of an interlock of the IO access device. The triggering step releases a lock pin disposed between the trigger and the output spool allowing the force applied to the bone at the distal end of the IO needle to start the rotation of the IO needle.

In some examples, the method further includes a detaching step of detaching the IO needle from a remainder of the IO access device; a removing step of removing from the IO needle an obturator removably disposed in a cannula; a confirming step of confirming the cannula is disposed in the medullary cavity by aspirating bone marrow through a syringe; a securing step of securing the cannula to the patient; and a starting step of starting interosseous infusion as boluses with a same or different syringe.

With respect to "proximal," a "proximal portion" or a "proximal-end portion" of, for example, a catheter includes a portion of the catheter intended to be near a clinician when the catheter is used on a patient. Likewise, a "proximal length" of, for example, the catheter includes a length of the catheter intended to be near the clinician when the catheter is used on the patient. A "proximal end" of, for example, the catheter includes an end of the catheter intended to be near the clinician when the catheter is used on the patient. The proximal portion, the proximal-end portion, or the proximal length of the catheter can include the proximal end of the catheter; however, the proximal portion, the proximal-end portion, or the proximal length of the catheter need not include the proximal end of the catheter. That is, unless context suggests otherwise, the proximal portion, the proximal-end portion, or the proximal length of the catheter is not a terminal portion or terminal length of the catheter.

With respect to "distal," a "distal portion" or a "distal-end portion" of, for example, a catheter includes a portion of the catheter intended to be near or in a patient when the catheter is used on the patient. Likewise, a "distal length" of, for example, the catheter includes a length of the catheter intended to be near or in the patient when the catheter is used on the patient. A "distal end" of, for example, the catheter includes an end of the catheter intended to be near or in the patient when the catheter is used on the patient. The distal portion, the distal-end portion, or the distal length of the catheter can include the distal end of the catheter; however, the distal portion, the distal-end portion, or the distal length of the catheter need not include the distal end of the catheter. That is, unless context suggests otherwise, the distal portion, the distal-end portion, or the distal length of the catheter is not a terminal portion or terminal length of the catheter.

As set forth above, PIVC insertions are increasingly challenging in emergency scenarios as critically ill patients deteriorate. Intraosseous ("IO") access is often the only means available to clinicians to increase the patient's chances of recovery and even save the patients' lives. However, better tuned medical devices are needed that can significantly reduce design and manufacturing complexity while optimizing user experience. Disclosed herein are constant-torque IO access devices and methods thereof that address the forgoing shortcomings.

<FIG> and <FIG> respectively illustrate a first IO access device <NUM> and a second IO access device <NUM> in accordance with some embodiments. <FIG> and <FIG> respectively illustrate the first IO access device <NUM> and the second IO access device <NUM> with a side of housing <NUM> or <NUM> removed in accordance with some embodiments. <FIG> illustrates a constant-torque spring assembly <NUM> in accordance with some embodiments.

As shown, the IO access device <NUM> or <NUM> includes the constant-torque spring assembly <NUM> or <NUM> disposed in the housing <NUM> or <NUM>, a drive shaft <NUM> extending from the housing <NUM> or <NUM>, and an IO needle <NUM> coupled to the drive shaft <NUM> configured to provide IO access to a medullary cavity of a patient.

The housing <NUM> or <NUM> houses components of the IO access device <NUM> or <NUM>. While the components of the IO access devices <NUM> and <NUM> are largely the same in terms of function, the components can be physically different in order to accommodate a particular form factor. For example, the IO access device <NUM> has a form factor for holding the IO access device <NUM> in a way that permits the IO needle <NUM> to access a medullary cavity of a patient with a stabbing motion. In contrast, the IO access device <NUM> has a form factor for holding the IO access device <NUM> in a way that permits the IO needle <NUM> to access a medullary cavity of a patient with in a more traditional drilling motion. The housing <NUM> or <NUM> is molded of a medically acceptable polymer such that sagittal halves of the housing <NUM> or <NUM> can be snapped or bound (e.g., mechanically fastened with fasteners, chemically bonded by adhesive, etc.) together around the components of the IO access device <NUM> or <NUM>.

The constant-torque spring assembly <NUM> or <NUM> includes a metal ribbon (e.g., a stainless-steel ribbon) <NUM>, at least a portion of which is reversely wound onto an output spool <NUM> and correctly wound onto a storage spool <NUM> with respect to a bias of the metal ribbon <NUM>. The metal ribbon <NUM> is configured to wind onto the storage spool <NUM> or into a storage cavity with a constant torque across a range of revolutions-per-minute ("RPMs") when the output spool <NUM> is released or otherwise allowed to do so.

The constant-torque spring assembly <NUM> or <NUM> is unique in that stresses associated with deflection of the metal ribbon <NUM> are not cumulative over an entire length of the metal ribbon <NUM>. The stresses are temporary and apply to only a short length (e.g., the exposed length) of the metal ribbon <NUM> at any given time. In addition, the metal ribbon <NUM> can be tuned with respect to any characteristic selected from its thickness, width, number of winds around the output spool <NUM>, and the like for configuration of the constant-torque spring assembly <NUM> or <NUM> with an optimal rotary action of the IO needle for IO insertion.

Each spool of the output spool <NUM> and the storage spool <NUM> optionally includes a spindle co-incident with an axis of the spool for mounting the spool in the housing <NUM> or <NUM>. Such a spindle can be on one side of the spool or both sides of the spool. For example, the constant-torque spring assembly <NUM> of the IO access device <NUM> includes spindle <NUM> and spindle <NUM> of the output spool <NUM> and spindle <NUM> and spindle <NUM> of the storage spool <NUM>. Likewise, the constant-torque spring assembly <NUM> of the IO access device <NUM> includes spindle <NUM> and spindle <NUM> of the output spool <NUM> and spindle <NUM> and spindle <NUM> of the storage spool <NUM>.

Alternatively or additionally to the foregoing spindles, each spool of the output spool <NUM> and the storage spool <NUM> optionally includes an axial channel co-incident with the axis of the spool, which can be for mounting the spool in the housing <NUM> or <NUM>, driving another component (e.g., the drive shaft <NUM>) of the IO access device <NUM> or <NUM>, etc. Such an axial channel can be in one side of the spool, both sides of the spool, or extending from one side of the spool to the other side of the spool. For example, the constant-torque spring assembly <NUM> or <NUM> of the IO access device <NUM> or <NUM> includes an axial channel <NUM>, which, in at least this case, includes a hexagonal shape to drive the hexagonal proximal-end portion of the drive shaft <NUM>. (See <FIG> and <FIG>. ) If the output spool <NUM> or the storage spool <NUM> includes a spindle on a side of the spool <NUM> or <NUM> and an axial channel in the same side of the spool <NUM> or <NUM>, the spindle has an outer diameter large enough to accommodate an inner diameter of the axial channel as shown in <FIG> by the spindle <NUM> and the axial channel <NUM>.

As shown in <FIG>, same-side spindles such as the spindles <NUM> and <NUM> respectively of the output spool <NUM> and the storage spool <NUM> can be coupled together by at least one elastomeric loop <NUM> (e.g., an 'O'-ring) to prevent any timing-related errors between the output spool <NUM> and the storage spool <NUM>. Such timing-related errors are possible if the metal ribbon <NUM> winds onto the storage spool <NUM> more slowly than the metal ribbon <NUM> winds off the output spool <NUM> - or vice versa. As shown, the elastomeric loop <NUM> includes a half twist such that it crosses over itself to match the rotational motion of both the output spool <NUM> and the storage spool <NUM>.

<FIG> illustrates an activation mechanism <NUM> for activating rotation of the IO needle <NUM> in accordance with some embodiments.

As shown, the activation mechanism <NUM> for activating rotation of the IO needle <NUM> includes the drive shaft <NUM> slideably disposed in the axial channel <NUM> of the output spool <NUM>, a set of drive-shaft teeth <NUM> around the drive shaft <NUM>, a set of opposing but complementary housing teeth <NUM> around an aperture of the housing <NUM> or <NUM> from which the drive shaft <NUM> extends, and a compression spring <NUM> between a back side of the set of drive-shaft teeth <NUM> and the output spool <NUM>.

In an inactive state of the IO access device <NUM> or <NUM>, a spring force is exerted on the back side of the set of drive-shaft teeth <NUM> by extension of the compression spring <NUM> between the back side of the set of drive-shaft teeth <NUM> and the output spool <NUM>. Extension of the compression spring <NUM> keeps the drive shaft <NUM> pushed out of the axial channel <NUM>, which also keeps the set of drive-shaft teeth <NUM> thereof away from the output spool <NUM> such that the set of drive-shaft teeth <NUM> and the set of housing teeth <NUM> are engaged with each other. Each set of teeth of the set of drive-shaft teeth <NUM> and the set of housing teeth <NUM> can include sawtooth-shaped teeth. When such sets of teeth are engaged with each other as in the inactive state of the IO access device <NUM> or <NUM>, rotation of the drive shaft <NUM> and, thus, the rotation of the IO needle <NUM> is prevented.

In an active state of the IO access device <NUM> or <NUM>, the spring force exerted on the back side of the set of drive-shaft teeth <NUM> by the extension of the compression spring <NUM> is overwhelmed by force applied to a distal-end portion of the drive shaft <NUM> by way of a distal end of the IO needle <NUM>. Compression of the compression spring <NUM> keeps the drive shaft <NUM> pushed into the axial channel <NUM>, which also keeps the set of drive-shaft teeth <NUM> thereof close to the output spool <NUM> such that the set of drive-shaft teeth <NUM> and the set of housing teeth <NUM> are disengaged with each other. When such sets of teeth are disengaged with each other as in the active state of the IO access device <NUM> or <NUM>, rotation of the drive shaft <NUM> and, thus, the rotation of the IO needle <NUM> is allowed.

In a transition between the inactive state and the active state of the IO access device <NUM> or <NUM>, force applied to the distal-end portion of the drive shaft <NUM> by way of, for example, engaging bone with the distal end of the IO needle <NUM>, simultaneously inserts the drive shaft <NUM> deeper into the axial channel <NUM> and compresses the compression spring <NUM> between the back side of the set of drive-shaft teeth <NUM> and the output spool <NUM>. Inserting the drive shaft <NUM> deeper into the axial channel disengages the set of drive-shaft teeth <NUM> from the set of housing teeth <NUM> to initiate the active state of the IO access device <NUM> or <NUM>, in which state rotation of the IO needle <NUM> is effectuated by the output spool <NUM> of the constant-torque spring assembly <NUM> or <NUM> on the drive shaft <NUM>.

In a transition between the active state and the inactive state of the IO access device <NUM> or <NUM>, force removed from the distal-end portion of the drive shaft <NUM> by way of, for example, disengaging the distal end of the IO needle <NUM> from bone, allows the compression spring <NUM> between the back side of the set of drive-shaft teeth <NUM> and the output spool <NUM> to relax, which pushes the drive shaft <NUM> out of the axial channel <NUM> away from the output spool <NUM>. Pushing the drive shaft <NUM> out of the axial channel <NUM> reengages the set of drive-shaft teeth <NUM> with the set of housing teeth <NUM> to initiate the inactive state of the IO access device <NUM> or <NUM>, in which state rotation of the IO needle <NUM> is by the output spool <NUM> of the constant-torque spring assembly <NUM> or <NUM> on the drive shaft <NUM> is prevented.

The transition between the active state and the inactive state of the IO access device <NUM> or <NUM> can be automatically initiated by the IO access device <NUM> or <NUM>. In such an IO access device, the compression spring <NUM> is configured by way of its material, construction, or both to have a spring constant and a compressible length proportional to a spring force greater than an average force that can be applied on the distal end of the IO needle <NUM> by marrow in a medullary cavity of a patient. Entry of the IO needle <NUM> into the medullary cavity of the patient automatically replaces the force applied on the distal end of the IO needle <NUM> by compact bone, which force is greater than the foregoing spring force, with the force applied on the distal end of the IO needle <NUM> by the marrow in the medullary cavity, which force is less than the foregoing spring force, thereby allowing the compression spring <NUM> to push the drive shaft <NUM> out of the axial channel <NUM> away from the output spool <NUM> to initiate the transition to the inactive state of the IO access device <NUM> or <NUM>. Notwithstanding the foregoing, the transition between the active state and the inactive state can be manually initiated by a clinician after feeling a change in tissue density upon entering the medullary cavity from compact bone.

As shown in <FIG> for at least the IO access device <NUM>, a combination of a molded piece <NUM> within the housing <NUM> and an extension pin <NUM> disposed in the axial channel <NUM> of the output spool <NUM> between the drive shaft <NUM> and the molded piece <NUM> is configured to stop over insertion of the drive shaft <NUM> into the axial channel <NUM> of the output spool <NUM> during the transition between the inactive state and the active state of the IO access device <NUM>. In addition to stopping the over insertion of the drive shaft <NUM> into the axial channel <NUM> of the output spool <NUM>, the combination of the extension pin <NUM> and the molded piece <NUM> is configured to decouple the force applied to the distal end of the IO needle <NUM> from the constant-torque spring assembly <NUM>. That is, any further force applied to the distal end of the IO needle <NUM> than that needed for the transition between the inactive state and the active state of the IO access device <NUM> is applied to the molded piece <NUM> of the housing <NUM> by the extension pin <NUM> instead of the constant-torque spring assembly <NUM>. Indeed, minimization of bearing surface area and reduction of extraneous moment arm lengths further decouple the force applied to the distal end of the IO needle <NUM> from the constant-torque spring assembly <NUM>.

As shown in <FIG>, the IO access device <NUM> further includes an interlock including a trigger <NUM> and a lock pin <NUM> disposed between the trigger <NUM> and the output spool <NUM> in the inactive state of the IO access device <NUM>. When pressed toward the housing, the trigger <NUM> is configured to release the lock pin <NUM> allowing the force applied to the distal end of the IO needle <NUM> to simultaneously compress the compression spring <NUM> and insert the drive shaft <NUM> deeper into the axial channel <NUM>.

As shown in <FIG>, the IO access device <NUM> further includes an interlock including a trigger <NUM> pivotally mounted on a transversely oriented pin <NUM> disposed between the trigger <NUM> and the output spool <NUM>. Both the trigger <NUM> and the output spool <NUM> have interlocking teeth that are interlocked in the inactive state of the IO access device <NUM>. When pressed toward the housing, the trigger <NUM> is configured to pivot about the pin <NUM> and withdraw the interlocking teeth of the trigger <NUM> from those of the storage spool <NUM> allowing the force applied to the distal end of the IO needle <NUM> to simultaneously compress the compression spring <NUM> and insert the drive shaft <NUM> deeper into the axial channel <NUM>.

While not shown, the IO access device <NUM> or <NUM> can further include a hand-actuated braking system configured to act on the output spool <NUM> to slow the metal ribbon <NUM> from winding onto the storage spool <NUM>. The braking system can be initiated at a start of the winding of the metal ribbon <NUM> onto the storage spool <NUM> or at any time throughout the winding.

The IO needle <NUM> is configured to separate from the IO access device <NUM> or <NUM> subsequent to achieving IO access to a medullary cavity of a patient. While not shown, the IO needle <NUM> includes an obturator removably disposed in a cannula. The cannula has a lumen configured for at least interosseous infusion upon removal of the obturator.

Methods of the IO access device <NUM> or <NUM> include at least a method of using the IO access device <NUM> or <NUM>.

A method of using the IO access device <NUM> or <NUM> includes at least an obtaining step of obtaining the IO access device <NUM> or <NUM>.

The method can also include a preparing step of preparing skin of the patient with an antiseptic (e.g., iodopovidone) at an insertion site of a patient. The insertion site can be about the proximal tibia, the distal tibia, or the distal femur.

The method can also include an inserting step of inserting the distal end of the IO needle <NUM> through the skin at the insertion site.

The method can also include an applying step of applying force to bone at the insertion site with the distal end of the IO needle <NUM>. In accordance with applying the force to the bone at the insertion site, the applying step includes inserting the drive shaft <NUM> deeper into the axial channel <NUM> of the output spool <NUM> of the constant-torque spring assembly <NUM> or <NUM>. The applying step also compresses the compression spring <NUM> between the back side of the set of drive-shaft teeth <NUM> around the drive shaft <NUM> and the output spool <NUM>. The applying step also disengages the set of drive-shaft teeth <NUM> from the opposing set of housing teeth <NUM> around the aperture of the housing <NUM> or <NUM> from which the drive shaft <NUM> extends to start the rotation of the IO needle <NUM>. The applying step starts winding the metal ribbon <NUM> of the constant-torque spring assembly <NUM> or <NUM> from the output spool <NUM> onto the storage spool <NUM>, thereby starting rotation of the IO needle <NUM>.

The method can also include a drilling step of drilling through the bone until the IO needle <NUM> enters a medullary cavity of the patient, thereby achieving IO access to the medullary cavity of the patient with the IO access device <NUM> or <NUM>.

The method can also include a ceasing step of ceasing to apply the force to the bone with the distal end of the IO needle <NUM>. The ceasing step removes at least a portion of the drive shaft <NUM> from the axial channel <NUM> of the output spool <NUM>, relaxes the compression spring <NUM>, and reengages the set of drive-shaft teeth <NUM> with the set of housing teeth <NUM> to stop the rotation of the IO needle <NUM>. The ceasing step can be automatically initiated by the IO access device <NUM> or <NUM> after experiencing a change in tissue density (e.g., compact bone to marrow) upon entering the medullary cavity of the patient. The ceasing step can alternatively be manually initiated by a clinician after feeling the change in tissue density upon entering the medullary cavity of the patient.

The method can also include a triggering step of triggering the trigger <NUM> or <NUM> of the interlock of the IO access device <NUM> or <NUM>. With respect to at least the IO access device <NUM>, the triggering step releases the lock pin <NUM> disposed between the trigger <NUM> and the output spool <NUM> allowing the force applied to the bone at the distal end of the IO needle <NUM> to start the rotation of the IO needle <NUM>.

The method can also include a detaching step of detaching the IO needle <NUM> from a remainder of the IO access device <NUM> or <NUM>.

The method can also include a removing step of removing from the IO needle <NUM> the obturator removably disposed in the cannula.

The method can also include a confirming step of confirming the cannula is disposed in the medullary cavity by aspirating bone marrow through a syringe.

The method can also include a securing step of securing the cannula to the patient with a dressing.

The method can also include a starting step of starting interosseous infusion as boluses with a same or different syringe.

Claim 1:
An intraosseous access device (<NUM>, <NUM>), comprising:
a constant-torque spring assembly (<NUM>, <NUM>) disposed in a housing (<NUM>, <NUM>);
a drive shaft (<NUM>) extending from the housing (<NUM>, <NUM>), the drive shaft (<NUM>) coupled to the constant-torque spring assembly (<NUM>, <NUM>); and
an intraosseous needle (<NUM>) coupled to the drive shaft (<NUM>) configured to provide intraosscous access to a medullary cavity of a patient,
wherein the constant-torque spring assembly (<NUM>, <NUM>) includes a metal ribbon (<NUM>) reversely wound onto an output spool (<NUM>), the metal ribbon (<NUM>) configured to wind onto a storage spool (<NUM>) with a constant torque when the output spool (<NUM>) is released, and
wherein spindles of the output spool (<NUM>) and the storage spool (<NUM>) are coupled together by at least one elastomeric loop (<NUM>) to prevent any timing-related errors between the output spool (<NUM>) and the storage spool (<NUM>).