Surgery – Instruments – Cutting – puncturing or piercing
Reexamination Certificate
1999-06-01
2002-06-11
Smith, Jeffrey A. (Department: 3732)
Surgery
Instruments
Cutting, puncturing or piercing
C606S185000
Reexamination Certificate
active
06402770
ABSTRACT:
TECHNICAL FIELD
The invention relates to emergency airway devices and emergency thoracostomy devices; more particularly, it relates to trocar devices and method and apparatus for a establishing and maintaining an emergency opening to a body cavity.
BACKGROUND OF THE INVENTION
Cricothyrotomy
A cricothyrotomy is an emergency procedure performed on a choking person to admit air into the lungs via an opening made in the cricothyroid membrane. The cricothyroid membrane lies between the cricoid and thyroid cartilages of the voice box and is easily located by palpation of the larynx and trachea. Only the thin skin of the throat covers the membrane; no large blood vessels, glands, or other critical structures are normally encountered if this site is used. Though this area is not well-suited to long-term, auxiliary airway maintenance, it offers the safest and most direct access in times of emergency. Presently available devices and methods for performing an emergency cricothyrotomy, however, have serious drawbacks for inexperienced personnel and are of limited effectiveness.
A tracheotomy is a surgical procedure used to admit air into the lungs when the normal breathing passage is obstructed or otherwise ceases to function properly. Briefly stated, a tracheotomy usually involves an incision through the skin of the neck below the level of the voice box and careful manipulation of the thyroid gland and several large blood vessels to expose the trachea. A small circular opening is made in the trachea and an endotracheal tube is inserted to maintain the opening and provide an airway. A tracheotomy is the procedure of choice when an auxiliary airway is to be maintained for an extended period. It is a delicate operation requiring the skill and knowledge of a surgeon and the facilities of a hospital emergency room. Unfortunately, the services of a surgeon and hospital facilities are usually not immediately available to someone who is choking. Unless the patient is given means to breathe, he will die in approximately three minutes. There are well-established non-surgical techniques for removing a supralaryngeal airway obstruction which should be utilized, whenever possible, before any surgical technique is applied. However, these non-surgical methods have a limited range of applicability and are sometimes ineffective. Therefore, there is a need for a device which will enable a person with limited training to provide an emergency airway at any location where a choking emergency occurs.
The inventor earlier created a class of emergency retractable trocar devices to address some of the above concerns, and they are described in U.S. Pat. No. 4,291,690 issued Sep. 29, 1981. However, at the time of the earlier invention, some of the requirements for a practicable, minimally traumatic and fully controllable cricothyrotomy airway were not addressed or dealt with.
Firstly, it is now appreciated that placement of a large trocar (7-8 mm O.D.) through the skin into the trachea is extremely difficult if an adequate surgical incision and sharp dissection of the underlying tissue layers is not accomplished prior to insertion. Extensive testing of many cutting tip and blade designs demonstrates that any blade that is no wider than the inside diameter of the cannula mounted on the trocar shaft and that is merely pushed straight in without any substantial lateral motion will not make an incision that is wide enough to allow a short, straight cannula to be pushed into the upper tracheal airway without excessive force and without extreme danger of over penetration and subsequent crushing trauma to underlying tissues, no matter what the shape or length of the blade. Trauma to the larynx during cricothyrotomy is the primary cause of subglottic stenosis, the most common but preventable complication.
In addition, uncontrolled lateral motion of a blade during incision into the cricothyroid ligament space can cut the recurrent laryngeal nerve resulting in vocal cord paralysis, another major complication of poorly done cricothyrotomy. If a scalpel is used to make a stab incision into the airway, it must be subsequently removed and some type of retractor or tissue separator inserted to enable placement of an airway. When the blade is taken out, the various tissue layers are free to slip relative to one and the path of insertion into the airway can be lost. Re-establishment of the path of insertion can be traumatic and time consuming if not impossible without re-incision.
Secondly, a fixed blade on the end of a trocar can lacerate or penetrate the posterior tracheal wall and esophagus during insertion. This is a potentially fatal complication.
Thirdly, full control of the airway and the ability to forcefully ventilate the patient requires placement of an adequately sized cuffed tracheotomy tube.
What is needed is an improved trocar device to address these additional requirements and any other concerns that arise in such emergency situations.
Thoracostomy
Trauma is the third leading cause of death in the United States and the leading cause of death in young people. Blunt and penetrating chest injuries account for a large number of trauma related deaths. A tension pneumothorax is one of the leading causes of death from chest trauma. A tension pneumothorax occurs when a patient suffers chest injuries resulting in a tear of the lung. Air escapes and builds up under tension outside of the lung in the pleural space. The air under tension changes the dynamics of the circulatory system by impeding blood return to the heart, resulting in severe shock and death if not immediately corrected. This can occur during positive pressure ventilation, when diseased lungs rupture more frequently, following direct chest trauma secondary to fractured ribs. A tension pneumothorax often develops rapidly after the lung injury and therefore the treatment of the tension pneumothorax is an important part of most emergency training protocols.
When a patient develops a tension pneumothorax there is an emergent need to decompress the thorax. When a tension pneumothorax is suspected, a procedure known as needle thoracostomy is typically performed to release the tension. A needle thoracostomy utilizes a large needle or an IV catheter with a one-way flutter valve. The needle is thrust blindly through the anterior chest to decompress the pneumothorax emergently. This procedure, sometimes referred to as “placing a flutter valve”, is routinely taught to physicians, nurses and paramedics during formal training, including the Advanced Trauma Life Support (ATLS) and Advanced Cardiac Life Support Courses (ACLS), courses given to most practitioners dealing with critically ill patients.
Although generally helpful, there are several drawbacks to the current needle thoracostomy procedure. The needle or IV catheter can easily lacerate the lung and produce further lung injury or hemothorax (bleeding into the chest). In fact, a chest tube must always be placed after a needle thoracostomy to treat the presumed needle injury from the procedure, even if the diagnosis of pneumothorax was incorrect! Most injuries to the lung produce some degree of hemothorax anyway, and that increases the chance that blood will clog the typically small caliber needle that is currently used. Today, most health care providers simply use an IV catheter or make-shift needles with balloons, finger cots, or slit finger tips of latex gloves on the end to decompress a tension pneumothorax.
In a typical scenario, a trauma patient with an injured lung develops profound shock after endotracheal intubation. This results because the air introduced under positive pressure escapes through the injured lung and a tension pneumothorax ensues. The paramedics would listen for decreased breath sounds, and if absent, would perform a needle thoracostomy by placing a needle or IV catheter through the side with the decreased breath sounds.
Another common scenario is the patient in extremis who fails to respond to resuscitation. As called for in the ATLS and ACLS protocols, needle thoracostomies are often perf
Avatar Design & Development, Inc.
Dwyer Patrick M.
Priddy Michael B.
Smith Jeffrey A.
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