Patent Application
20050197647
The invention relates to devices used to collect blood and other fluids from a patient during and following a medical procedure. In particular, the invention relates to devices and methods for post-operative drainage of fluids from a surgical site.
Automated devices configured to collect blood and other fluids from a surgical site are common. In a post-operative setting, such devices may be configured as an autotransfusion system that returns collected blood back to the patient after processing and filtering. The collection devices operate by providing suction through a conduit such as tubing that is connected to a drain catheter placed at the surgical area. Blood and fluids are suctioned into the tubing and carried to a reservoir external to the patient.
Though collection of fluids from an internal surgical site is important to the recovery of the patient, there are risks involved with introducing suction to a surgical site. One danger to the patient is improper flow through the tubing placed at the surgical site. If suction is applied that is too strong, the treatment area, as well as organs and tissues adjacent to it, may be disturbed and negatively impacted. Another concern is reversal of flow back to the surgical site through the tubing if suction is discontinued. For example, in the absence of suction through a drain catheter placed in a chest cavity, normal breathing and movement of the diaphragm to expand the lungs will create vacuum in the cavity that could suction the contents of the catheter and tubing back to the surgical site. Flow through the tubing could impact a patient's breathing as suction in the chest cavity to inflate the lungs is reduced by the pressure leak represented by the catheter. Also, the re-introduction of possibly contaminated fluids and blood to the site could lead to infection or other complications.
The concerns discussed above are significant in a post-operative environment, because tissues and organs of the surgical site are weakened and more susceptible to damage by improper flow that may accidentally be introduced through the suction tubing of a blood collection device. Maintaining proper suction levels is important in post-operative collection devices, and especially for perioperative collection systems that are used during surgery and also postoperatively. Perioperative devices collect blood at higher suction levels during surgery then must transition to lower suction levels as their use continues during the post-operative period in order to reduce trauma to the surgical site. A risk exists that a perioperative device may accidentally be operated at high intraoperative suction levels that are too high for a post-operative condition, possibly damaging tissues or organs at the surgical site. The consequences of such an error would be especially damaging of occurring during use of a perioperative device in a procedure carried out in the chest cavity, such as a cardiac or spinal procedure, because of the proximity of critical organs such as the heart and lungs.
It would be desirable to provide flow control safe guards in the suction/fluid pathway of a blood collection device that would ensure that suction levels did not increase to an unsafe magnitude and that prevented positive reversal of flow through the collection tubing. It also would be desirable to provide such safeguards built into a component of the collection system that operators must use with each new procedure, such as part of a disposable set, so that the safeguards are certain to be in place regardless of the age and safety features of the permanent hardware and equipment. It is an object of the present invention to provide devices and methods for employing such flow control safeguards.
The present invention provides a surgical drain tube having one or more components that serve to control the flow through the tube in a manner that is safe for the patient and non-disruptive to the post-operative surgical site. In particular, the drainage tube may be configured as a length of tubing configured to extend between a drainage catheter placed at the operative site in a patient and a blood collection device such as an autotransfusion device that can be operated to apply suction to the tubing to remove blood and other fluids from the site in order to promote healing. The tubing is configured with one or more flow control features built into it to ensure that flow occurs only in the correct direction and only at suction levels that are suitable for the surgical site.
In one aspect of the invention, the surgical drain tube may be configured to have a vacuum relief valve placed in fluid communication with the fluid/suction pathway defined by the lumen of the tubing in order to prevent suction in the line that is too great for the organs and tissues at the surgical site. The valve is configured to open automatically when vacuum levels in the fluid/suction pathway exceed a predetermined level above which tissues and organs could be disturbed. If a suction level that is greater than the pre-determined level is encountered in the lumen of the tubing, the valve will open automatically to a source of reduced suction, such as atmospheric pressure, and the suction force in the drain will be reduced to an acceptable level.
In another aspect of the invention an anti-reflux valve may be employed in-line in the drain tube. The anti-reflux valve is a check valve that permits fluid flow through the lumen of the tubing in only one direction. The valve is arranged to maintain flow away from the patient. The tubing can be further configured to have fail-safe connectors at its ends so that it can only be joined to the drainage catheter and collection device in an orientation that arranges the anti-reflux to maintain flow away from the patient.
With the anti-reflux valve in place, air and liquid being suctioned from the surgical site will not be free to flow backwards toward the patient if the suction is discontinued. In a procedure carried out in the chest cavity suction is generated as the diaphram moves to expand the lungs. A drain tube in place without such a valve provides an open fluid pathway into the chest cavity reducing suction needed to fill the lungs with air to carry out breathing. Additionally, reverse suction though the drain tube can be generated, drawing in blood and fluids previously drained from the surgical site. At a minimum such an occurrence hampers progress of cleaning the site from contaminants and blood from the surgery, but also fluid build up in the cavity could be harmful to adjacent organs such as the lungs.
The inventive drain tube may employ either one or both of the flow control safeguards discussed above.
It is the object of the present invention to provide safeguards for controlling flow through a surgical drain tube so that the patient is not injured by undesirable flow characteristics through the tube.
It is another object of the invention to provide a surgical drain tube having one or more flow control devices that insure flow characteristics through the tube that are not deleterious to the condition of the treatment site and surrounding area.
It is another object of the invention to provide a surgical drain tube having an in-line anti-reflux valve to ensure fluid through the tube flows only away from the patient.
It is another object of the invention to provide a surgical drain tube having a suction relief valve in fluid communication with the lumen of the drain tube and that automatically vents to a source of reduced suction or to atmospheric pressure when suction levels in the drain tube exceed a predetermined threshold.
It is another object of the invention to provide a surgical drain tube having an in-line anti-reflux valve and integral suction relief valve to ensure that flow in the drain tube is maintained in the proper direction and at appropriate levels for the patient.
It is another object of the invention to provide a surgical drain tube that is compatible for use with a variety of blood collection devices but especially with perioperative autotransfusion systems including systems intended for use in the chest cavity for cardiac procedures.
It is another object of the invention to provide a method of controlling of the flow through a surgical drain tube that comprises integrating one or more flow control safeguards.
The foregoing and other objects and advantages will be appreciated more fully from the following further description thereof, with reference to the accompanying diagramatic drawings wherein:
The anti-reflux valve 26 ensures that the flow occurs only in the direction indicated by arrows 32 shown in
An external manual ratchet clamp 34 may be provided with the drain tube 10 to provide an operator with the capability of manually preventing flow through the tube during its set up with a drain catheter and blood collection device device. Also, end caps 36 may be provided over the ends of tube 10 to prevent contamination during shipping and storage and are removed just prior to use. In connecting the tube 10 to the drain catheter and auto transfusion device a fail-safe connection fitting 38 ensures the operator does not connect the tubing in reverse. A fail-safe fitting 38 may be integrated either at the device end 22 or patient end 24 of the tube and is configured to mate only with a compatible fitting located on the end of the drainage catheter or on the collection device. In the example shown in
The collection device 14, such as autotransfusion device 16, has a pump mechanism that creates suction in the fluid/suction pathway to which the tube 10 is connected. The device 16 may be a perioperative device that can be used during both intraoperative and post operative site drainage. Because a perioperative device must operate at higher suction levels during an operation, then operate at reduced suction levels in the postoperative environment to avoid damage to the tissues at the now closed surgical site, the tube of the present invention offers an important benefit. When the post operative drain tube of the present invention is installed to the drain catheter and to the device, the danger of operating the device at the higher suction levels intended for an intraoperative environment is eliminated because the vacuum relief valve 28 will instantly and automatically relieve the suction levels to avoid injury if suction is too great. This flow control safety feature is especially important in procedures carried out in the chest cavity such as cardiac or spine procedures where suction is likely to affect vital organs such as the lungs and heart.
An example of a perioperative autotransfusion device is the OrthoPAT® manufactured by Haemonetics Corporation and described in U.S. Pat. No. 5,733,253. The OrthoPAT®) device 16 is shown as the collection device 14 in the example illustrated in
In use, the variable volume rotor 302 is held onto and spun by a centrifuge chuck 304. The chuck 304 holds the rotor 302; the chuck 304 has a clamp 308 that holds the rotor 302 securely in place in the chuck 304, and an O-ring 335 that forms an air-tight seal. A drive motor 350 is connected to the chuck 304 by means of a shaft 351. In order to apply a vacuum or pressure to the rotor 302 to pump fluid in and out of the rotor, respectively, the shaft 351 has an axial hole through its center 353 and is connected to a rotary pneumatic seal 355, which in turn is connected by tubing 359 to a compressor/vacuum pump 361 and to a controllable exhaust valve 363. Holes 365 in the interior of the chuck 304 allow air to flow to and from the compressor/vacuum pump 361. These spinning and pumping mechanisms are controlled by a controller 117.
To draw blood from the wound, controller 117 controls the compressor/vacuum pump 361 to provide a vacuum through the chuck to the exterior side of the diaphragm 331. Because the diaphragm 331 is pulled downward by the vacuum in the chuck 304, an area of low pressure is created in the chamber, causing suction to be applied at the drain catheter 102. Consequently, fluid is drawn into the rotor 302 through the rotor tube 122. As more and more fluid enters the rotor 302, the diaphragm 331 changes shape to accommodate it. In this manner, blood and/or other fluid is drawn from the wound-drain site through the drain catheter 112 and associated tubing 122/valving 149 into the rotor 302.
In the body of the valve 26 is a flexible parachute valve element 46 joined to a patient side interior wall 48 by a plurality of flexible legs 50. The valve element may be integrally formed with the legs from silicon material. Such a valve is commercially available from Resenex Corporation of Chatsworth Calif. under part number R-702HF.
In
In
The suction force acting on frusto-conical element 74 that is necessary to move the piston 76 and to open the valve is predetermined by the configuration of biasing spring 80. The biasing spring extends around the piston 76 in the vent chamber 78 and is compressed between valve wall 84 and spring flange 82 located at the end of piston 76. Spring guide 86 formed on the inner face of the spring flange helps to keep the spring concentric relative to the piston. The spring is biased in its expanded configuration to push spring flange 82 away from valve wall 84 so that piston flange 68 normally closes opening 66. However, the spring is configured to have a spring force that permits the spring to compress when the suction force experienced in the suction chamber reaches a predetermined level. When the predetermined suction level is reached, the spring begins to compress under the suction forces applied to frusto-conical element and the piston moves in the direction of the suction force (leftward) to open valve. For procedures carried out in the chest cavity, spring is calibrated to open the valve when approximately 70 cm H2O of vacuum is reached in the suction pathway of the tube 10 and suction chamber 62 of the valve.
As the valve starts to open, the suction flow enters the vent chamber 78 through the opening 66. Suction pulls on the spring flange 82 of piston 76 to further open the valve. Vent cavity port 88 is open to ambient (atmospheric) pressure which effectively vents the tube of the excess suction. Alternatively, the vent cavity could be in communication with a closed environment that is at a reduced suction level or at positive pressure in order to reduce the amount of vacuum in the suction pathway of the tube 10 when valve 26 is opened. A vacuum relief valve such as that discussed above is commercially available from Smart Products of San Jose, Calif. under part no. 130 CYB-1#.
As best seen in
In use, the surgical drain tube is provided to the user as an assembled, one-piece disposable component integrating one or more of the flow control safeguards discussed above. After a surgical procedure, one or more drain catheters have already been placed at the surgical site and the site closed. The end of the drain catheter is left available outside the patient for connection to a post-operative surgical drain tube. The user removes a cap 36 from the patient end 24 of the tube and attaches it to the end of the drain catheter using a ribbed inner sleeve insertable into the lumen of the catheter and into the lumen of the drain tube. If equipped with a fail-safe connector at the device end 22, the user will be unable to connect the wrong end of the drain tube to the drain catheter, and correct orientation of the tube to obtain proper flow through the anti-reflux valve will be ensured.
Next, the user removes the cap 36 from the device end 22 of the tube and secures the end to the collection device 14. If fail-safe connections 38 and 40 are employed, the connection may be a snap fit or quick-release clamp or the like employing a tongue on one fitting and mating groove on the other.
The operator then may start the collection device to begin suction through the system. If the suction is inadvertently set too high for a post-operative environment, the vacuum relief valve 26 will open automatically to vent the tube 10 to a source of higher pressure. If suction is discontinued, for example by powering off the collection device, the anti-reflux valve prevents reverse flow of fluid through the tube back to the patient.
Accordingly, a surgical drain tube with flow control safeguards has been described. The tube is easy to use in a postoperative wound drain procedure. Because it integrates safeguard features all in one disposable tubing set, the safety benefits can be enjoyed with existing equipment and cannot be inadvertently by-passed, ensuring a safer procedure for the patient.
It should be understood, however, that the foregoing description of the invention is intended merely to be illustrative thereof and that other modifications, embodiments and equivalents may be apparent to those skilled in the art without departing from its spirit. Having thus described the invention what we desire to claim and secure by letters patent is:
