What are Internal Tourniquets?
A recent US patent for an ‘internal tourniquet for surgery’ [1] described innovation that opens the door to extending tourniquet-related concepts to surgical procedures not previously amenable to conventional tourniquets, especially procedures near truncal-extremity junctions, including hip and shoulder regions, and in the deep abdomen. Synergies exist by integrating this internal tourniquet innovation with related new concepts of ‘tourniquet effectors’ and ‘ultrasonic tourniquets’ [1-4].
Figure 1: Block diagram of an internal tourniquet. From US patent 7,981,070 – Internal Tourniquet for Automatically Controlling Hemostasis within a Joint Capsule [1].
What is an internal tourniquet?
An internal tourniquet manages the flow of sterile fluid into and out of a capsule that envelops a joint, thereby to help establish a pressure within the capsule that may reduce bleeding and improve visualization, and to help remove surgical debris and blood that may be present in the capsule. Internal tourniquets are used when external tourniquet system is not used, or cannot be used due to its limitations.
Limitations of external tourniquets
External tourniquet systems have long been used to establish hemostasis in the upper and lower limb in order to facilitate orthopedic surgical procedures. Such systems typically include a pneumatic tourniquet cuff applied around a patient’s limb proximal to a desired surgical field, and an external tourniquet instrument for supplying the cuff with gas at a pressure above the minimum pressure needed to stop arterial blood flow past the cuff and into the surgical field for the duration of a surgical procedure. In this way, an external tourniquet system establishes a bloodless and clear surgical field in the limb distal to the cuff, allowing complex orthopedic surgical procedures to be performed with improved accuracy, safety and speed.
However, in addition to establishing a bloodless surgical field, external tourniquet systems also stop blood flow to non-surgical regions of the limb, resulting in ischemia and a risk of injury to these non-surgical regions that increases as the duration of ischemia increases. Further, external tourniquet systems apply pressure to underlying muscle, blood vessels and nerves proximal to the surgical site, resulting in a risk of injury to these tissues that increases as the level of pressure and duration of pressure application increases.
In addition, anatomical considerations in certain surgical procedures, such as in hip and shoulder surgeries, may limit or completely prevent the use of external tourniquet systems for establishing hemostasis.
Alternatives to external tourniquets in joints, at truncal-extremity junctions and in the deep abdomen
If an external tourniquet system is not used, or cannot be used, then other devices have been used in the past to improve visualization and reduce bleeding, especially for arthroscopic surgical procedures. Some of these devices manage the flow of sterile fluid into and out of a capsule that envelops a joint, thereby to help establish a pressure within the capsule that may reduce bleeding and improve visualization, and to help remove surgical debris and blood that may be present in the capsule. Some of the fluid management systems that have been used for arthroscopies require significant manual intervention, knowledge, skill and attention by the surgeon throughout a surgical procedure in order to balance a number of competing requirements: the control of bleeding in the surgical field, the minimization of extravasation or swelling of tissues surrounding the surgical field and its associated risk of patient injury; the removal of blood and surgical debris from the surgical field; the maintenance of acceptable visualization; and the minimization of fluid loss and its related costs and hazards.
Advances in internal tourniquet technology
To facilitate new orthopedic surgical procedures that are becoming less invasive, as well as to facilitate arthroscopic surgical procedures that are becoming increasingly complex, the innovation described in the newly issued US patent meets the need for an internal tourniquet that can establish adequate hemostasis and provide a sufficiently bloodless surgical field when conventional external tourniquets cannot be used. The innovation does this without the limitations in performance and without many of the risks of patient injuries associated with prior-art external tourniquet systems and arthroscopic fluid management systems. Meeting this need, as described in the new US patent and in combination with ultrasonic tourniquet innovations and tourniquet effector innovations [1-4], opens the door to extending tourniquet-related concepts to surgical procedures not previously amenable to conventional tourniquets, especially in the abdomen and near truncal-extremity junctions including hip and shoulder regions.