Patent Description:
A typical example of such a surgical instrument is a Veress needle, hereinafter referred to as VN. The known VN is used to gain initial access to a peritoneal cavity of a patient to establish pneumoperitoneum. The use of the VN involves a blind insertion into the peritoneal cavity of the patient.

The use of the VN is probably popular because of its simplicity and effectiveness. It involves making a small incision in or near the umbilicus or in the left upper quadrant of the abdomen and then, in a blind fashion, putting the needle through the subcutaneous tissue, abdominal wall and the parietal peritoneum into the abdominal cavity. The VN technique is based on the ability of its blunt inner stylet to spring forward (since it is spring loaded) and to cover the sharp bevelled tip outer cannula when resistance diminishes after all tissue layers are passed. However, the surgeon cannot totally rely on this mechanism and therefore needs to develop a sense of the appropriate angle of insertion and the appropriate force to successfully puncture through the abdominal wall without overshooting into the underlying organs. The risk of damaging the underlying tissue with the tip of the cannula becomes high, when the reaction force that is generated by the abdominal wall drops to nearly zero (inside the abdominal cavity) in an instant. This immediate loss of resistance on the tip of the VN after puncturing causes acceleration of the needle towards the underlying tissues due to the slow reaction of the human control system, absence of stiff lower arm/hand support and relatively large mass of the surgeon's arm. Therefore, skilled and safe use of the VN requires a long learning curve to achieve the best possible instrument handling to prevent overshoot. Moreover, every patient's abdomen presents unique operating conditions, of which the specifics are unknown to the surgeon prior to the operation. These include the presence of adhesions, positions of the underlying tissues and viscera and the thickness of the abdominal wall.

In the prior art different proposals exist to counter the above mentioned problem of overshooting.

<CIT> proposes an instrument wherein the surgeon sets a maximal insertion depth. Unfortunately, the tissue layer thickness is not always known and layers are flexible making adjustment of the insertion depth difficult.

<CIT> allows overshooting but fixates the Veress mechanism as soon as it shoots in position. It seems however possible that even a blunt stylet with locked outer cannula can easily damage internal structures.

The articles by <NPL>, and by <NPL> focus on expanding the blunt area of the tip directly after insertion in order to reduce the stress when the tip hits underlying organs or structures.

The articles by <NPL>, and by <NPL>, report on the possibility to acquire information about intracorporeal tissue tool interactions of the VN tip, utilizing acoustic emissions or optic information recorded at the extracorporeal end of the needle.

The article by <NPL> teaches to create a vacuum cup around the VN. When sucking the air out of the cup the abdominal wall is lifted away from the critical structures when the VN penetrates the tissue. A disadvantage here is that the surgeon loses manipulation flexibility as the configuration of the needle is fixed.

Finally, overshooting can be prevented by introducing a faster control system. This can be done by linking a robot arm with haptic sensation to the VN's body that generates the driving force, as is suggested by<NPL>.

Although some of the proposals show interesting results, the complex nature of the proposed systems and the impact on workflow jeopardizes broader acceptance. It is therefore an object of the invention to provide a surgical instrument which is devoid of the complications of the known proposals, and which impairs the surgeon's operations as little as possible, so as to keep close to the surgeon's existing operational practices.

According to the invention a surgical instrument is proposed according to one or more of the appended claims. It is noted that although the previous discussion concentrates on the application of a VN, as the above recited preamble indicates the invention has broader application and relates to any surgical instrument for piercing into a human or animal body, wherein said instrument comprises an inner portion which is movably arranged within an needle-like outer portion, wherein said outer portion connects to the inner portion through a spring so as to provide with the outer portion during use a load on the inner portion, and wherein said outer portion is provided with a proximal sleeve that provides a finger grip to a surgeon. Examples thereof are for instance direct sharp trocar entries during laparoscopic surgery, and chest tube thoracostomies emergency or elective surgical airway.

<CIT> discloses an instrument with features according to the preamble of claim <NUM>, i.e. wherein the sleeve is releasably connectable to the outer portion and the instrument is provided with a release mechanism for releasing the sleeve from the outer portion, which release mechanism is actuable by motion of the inner portion.

In the instrument of the invention the outer portion is provided with a proximal ring or edge, and the sleeve is provided with a displaceable hook for hooking behind the ring or edge and thus provide a connection between the outer portion and the sleeve, wherein the release mechanism can be operable on the hook to remove it from its position behind the ring or edge. This makes possible that when the sleeve is used by the surgeon or a robot to push and insert the outer portion in the peritoneal cavity of a patient, the sudden drop of resistance when the insertion is accomplished and which is followed by an immediate forward movement of the spring-loaded inner portion, will have the effect that the inner portion activates the release mechanism which then neutralizes the driving force that the surgeon or robot applies to the sleeve, due to its release from the outer portion.

Suitably the release mechanism is mounted proximal on the inner portion and is arranged to operate on the hook of the sleeve when the inner portion moves towards the sleeve so as to release the sleeve from the outer portion.

The construction of the surgical instrument of the invention can be operationally effective and still be provided at limited cost when the release mechanism comprises a slanting first contact surface that is tailored to a correspondingly slanting second contact surface that is provided on the hook.

It is preferred that the hook is resiliently mounted on the sleeve so as to provide that the hook is displaced from its position behind the ring or edge of the outer portion at the time that the slanting first contact surface of the release mechanism impacts the second contact surface that is provided on the hook.

Suitably the release mechanism comprises a lever arm which is mounted proximal on the inner portion.

Optionally the proximal sleeve of the instrument is provided with an extension comprising one of a breathing tube or trocar tube. This relates to using the surgical instrument of the invention for intubating the trachea or intubating the abdominal wall with a trocar, respectively.

The invention will hereinafter be further elucidated with reference to the drawing of an exemplary embodiment of a surgical instrument according to the invention that is not limiting as to the appended claims.

Whenever in the figures the same reference numerals are applied, these numerals refer to the same or similar parts.

A Veress needle as shown in the figures is used for piercing into a human or animal body. As shown in <FIG> and in <FIG> the instrument <NUM>, <NUM> comprises an inner portion <NUM>, <NUM> which is movably arranged within a needle-like outer portion <NUM>, <NUM>, wherein said outer portion <NUM>, <NUM> connects to the inner portion <NUM>, <NUM> through a spring. In the prior art instrument <NUM> the spring is depicted with reference <NUM>. The detail A of the proximal portion of the instrument <NUM> of the invention which is shown in <FIG>, shows the spring as being depicted with reference <NUM>.

Both in the prior art instrument <NUM> and in the instrument <NUM> of the invention, the spring serves to apply with the outer portion <NUM>, <NUM> during use a load on the inner portion <NUM>, <NUM>. In connection therewith said outer portion <NUM>, <NUM> is provided with a proximal sleeve <NUM>, <NUM> that provides a finger grip for a surgeon. So far the prior art instrument <NUM> and the instrument <NUM> of the invention have corresponding features, albeit that the construction of the proximal sleeve <NUM> of instrument <NUM> differs from the proximal sleeve <NUM> of instrument <NUM>.

The instrument <NUM> of the invention differentiates from the prior art in that the sleeve <NUM> is releasably connectable to the outer portion <NUM> and that the instrument <NUM> is provided with a release mechanism for releasing the sleeve <NUM> from the outer portion <NUM>, which release mechanism is actuable by motion of the inner portion <NUM>. The manner in which this can be preferably embodied is further explained with reference to the detail of the instrument of the invention as depicted in <FIG>.

In <FIG> it is shown that the outer portion <NUM> is provided with a proximal ring or edge <NUM>, and that the sleeve <NUM> is provided with a displaceable hook <NUM> for hooking behind the ring or edge <NUM> and thus provide a connection between the outer portion <NUM> and the sleeve <NUM>. The release mechanism <NUM>, which comprises a lever arm mounted proximal on the inner portion <NUM> can then be operable on the hook <NUM> to remove it from its position behind the ring or edge <NUM> according to the following elucidation.

The release mechanism <NUM> is mounted proximal on the inner portion <NUM> and is arranged to operate on the hook <NUM> of the sleeve <NUM> when the inner portion <NUM> moves towards the sleeve <NUM> so as to release the sleeve <NUM> from the outer portion <NUM>. To that end it is preferable that the release mechanism <NUM> comprises a slanting first contact surface <NUM> that is tailored to a correspondingly slanting second contact surface <NUM> that is provided on the hook <NUM>. The hook <NUM> is resiliently mounted on the sleeve <NUM> by means of the resilient support <NUM> so as to provide that the hook <NUM> can be displaced from its position behind the ring or edge <NUM> of the outer portion <NUM> at the time that the slanting first contact surface <NUM> of the release mechanism <NUM> impacts the second contact surface <NUM> that is provided on the hook <NUM>.

Turning now to <FIG>, the surgical instrument of the invention is shown wherein the proximal sleeve <NUM> is provided with an extension in the form of a breathing tube <NUM>'. This construction is used for intubating the trachea. After piercing, all parts of the instrument <NUM> except for the sleeve <NUM> with the breathing tube <NUM>' shoot backwards and can be removed from the surgical site. Than the proximal sleeve <NUM> is removed from the breathing tube <NUM> that remains in place for breathing.

<FIG> shows another application which is used for piercing the abdominal wall with a trocar. After piercing, all parts of the instrument <NUM> except for the sleeve <NUM> with an extension embodied as a trocar tube <NUM>'' shoot backwards and can be removed from the surgical site. Then the proximal sleeve <NUM> is removed from the trocar tube <NUM>'' that remains in place for instrument guidance towards the abdominal cavity.

Claim 1:
A surgical instrument (<NUM>) for piercing into a human or animal body, said instrument (<NUM>) comprising an inner portion (<NUM>) which is movably arranged within an needle-like outer portion (<NUM>), wherein said outer portion (<NUM>) connects to the inner portion (<NUM>) through a spring (<NUM>) so as to provide with the outer portion (<NUM>) during use a load on the inner portion (<NUM>), wherein said outer portion (<NUM>) is provided with a proximal sleeve (<NUM>) that provides a finger grip to a person, usually a surgeon, wherein the sleeve (<NUM>) is releasably connectable to the outer portion (<NUM>) and the instrument (<NUM>) is provided with a release mechanism (<NUM>) for releasing the sleeve (<NUM>) from the outer portion (<NUM>), which release mechanism (<NUM>) is actuable by motion of the inner portion (<NUM>), characterized in that the outer portion (<NUM>) is provided with a proximal ring or edge (<NUM>), and that the sleeve (<NUM>) is provided with a displaceable hook (<NUM>) for hooking behind the ring or edge (<NUM>) and thus provide a connection between the outer portion (<NUM>) and the sleeve (<NUM>), wherein the release mechanism (<NUM>) can be operable on the hook (<NUM>) to remove it from its position behind the ring or edge (<NUM>).