METHODS AND DEVICES TO DECREASE TISSUE TRAUMA DURING SURGERY
Methods and devices are disclosed to reduce tissue trauma when a physician retracts a patient's tissues for surgery. In one part, methods and devices are disclosed for controlling retraction force and pace. In another part, methods and devices are disclosed for oscillating force when opening. In another part, methods and devices are disclosed for detecting trauma during retraction. In another part, methods and devices are disclosed for balancing forces on multiple retraction elements. In another part, methods and devices are disclosed for reducing forces in multiple dimensions. In another part, methods and devices are disclosed for engaging ribs. In another part, methods and devices are disclosed to compensate for deformation of a retractor under load. In another part, methods and devices are disclosed that combine these methods and devices. In another part, methods and devices are disclosed for controlling pressure inside inflatable devices used for deforming biological tissues.
1 . A thoracic retractor for performing a thoracotomy, comprising:
a linear drive element defining a direction of retraction;
at least two arms oriented substantially perpendicular to the direction of retraction, at least one of the at least two arms moveable along the linear drive element; and
at least one self-balancing tissue engager associated with each arm, the at least one self-balancing tissue engager comprising:
a first rotary joint defining a substantially vertical first axis of rotation associated with the arm;
a first balance bar having two ends, and attached between the first balance bar's two ends to the first rotary joint; and
the first balance bar's two ends each having a second rotary joint having a substantially vertical second axis of rotation, two second balance bars, each having two ends and each two ends each having a third rotary joint having a substantially vertical third axis of rotation, about each of which rotates a descender post descending from the ends of the second balance bars. Thus four descender posts are on each self-balancing tissue engager.
2 . The device as in claim 1 , where there are two, opposing self-balancing tissue engagers, each comprising:
one doubletree balance bar unit, comprising:
two swingletree balance bars, one on each end of the doubletree balance bar; and
one descender post on each end of the swingletree balance bars, for a total of four descender posts.
3 . A tissue engager for a thoracic retractor for performing a thoracotomy, comprising:
at least one balance bar oriented substantially perpendicular to a direction of retraction and capable of moving along the direction of retraction;
at least one descender post descending from the at least one balance bar, the descender post comprising:
an elongate member having first and second ends and a first rib-forcing surface adjacent the second end;
a hook element disposed adjacent the second end of the elongate member, the hook element comprising a first hook end and a second hook end, and a second rib-forcing surface adjacent the second hook end, thereby defining thereby a gap region between the first rib-forcing surface and the second rib-forcing surface; and
the gap region being concave and possessing a length along the direction of retraction configured to place the second rib-forcing surface substantially away from the neurovascular bundle.
4 . The tissue engager of claim 3 , where the concave shape of the gap region is further defined as a tapered hollow defining a taper point.
5 . The tissue engager of claim 4 , where the taper forms an acute angle.
6 . The tissue engager of claim 4 , where the taper is logarithmically curved.
7 . The tissue engager of claim 4 , comprising a plurality of the descender posts.
8 . The tissue engager of claim 7 , wherein the plurality of descender posts are comprised of a plurality of balanced descender posts.
9 . A tissue engager for a thoracic retractor for performing a thoracotomy, comprising:
at least one retraction bar capable of moving along a direction of retraction;
at least one descender post descending from the at least one retraction bar, comprising:
an elongate member having first and second ends and a first rib-forcing surface adjacent the second end; and
a hook element disposed adjacent the second end of the elongate member, the hook element comprising a first hook end and a second hook end, and a second rib-forcing surface adjacent the second hook end; and
the at least one retraction bar further comprising at least one rotational mount configured to rotate about a first rotational axis oriented substantially vertical with respect to a plane of a patient's skin engaged by the at least one descender post.
10 . The device as in claim 9 , wherein the at least one descender post is substantially curved, and where the first rib-forcing surface projects a nonzero distance radially out away from the substantially vertical axis, defining thereby a moment arm reaching out from the substantially vertical axis to the first rib-forcing surface.
11 . The device as in claim 9 , wherein the curved descender post is configured to rotate about the substantially vertical axis by at least 90 degrees.
12 . The device as in claim 1 , where the self-balancing tissue engagers are associated with an elastic element that confers the property of elastic recoil upon the self-balancing tissue engagers.
13 . The device as in claim 1 , where the first joint axis is associated with an elastic element.
14 . The device as in claim 1 , where the second joint axis is associated with an elastic element.
15 . The device as in claim 1 , where the third joint axis is associated with an elastic element.
16 . The device as in claim 1 , where the entirety of the self-balancing tissue engagers are substantially encompassed by an elastic sheath.
17 . The device as in claim 10 , where the Young's modulus of the elastic element is between 0.1 MPa and 60 MPa, first, permitting the preservation of the curved descender posts as a flat array for easy handling and insertion, and second, permitting the gentle, automatic deployment of the curved descender posts as retraction begins, and third, permitting the automatic re-flattening of the array curved descender posts as the surgeon closes the patient's incision after the procedure.
18 . The device as in claim 3 , where the Young's modulus of the elastic element is between 0.75 MPa and 1 MPa.
19 . The device as in claim 10 , where the elastic element is spatially associated with the gap region, and provides a padded surface to the patient's surrounding tissues.
20 . A method for retracting thoracic tissue, comprising:
retracting thoracic tissue in the direction of a linear drive element by moving along the linear drive element at least one of two arms oriented substantially perpendicular to the direction of retraction; while
engaging the tissue with each arm using a self-balancing tissue engager attached to each arm, while the self-balancing tissue engager automatically balances the forces amongst four descending posts.