Disposable Central Venous Catheter And Method Of Use

Abstract

A catheter composed of a length of flexible tubing composed of nonreactive material permitting protracted intravenous placement during periods of intensive care for intravenous feeding and administration of drugs and for monitoring central venous pressure, the catheter being provided with an electrical conductor extending lengthwise of the tubing and providing an electrode at the distal end positioned for sensing intrathoracic EKG activity unaffected by material discharged from the distal end and additionally providing such intrathoracic EKG activity simultaneously with the monitoring of intravenous pressure.

Description

Catheters of the character described are inserted into the superior vena cava of patients as, for example, in intensive care wards for the monitoring and treatment of heart patients or in any situation where central venous pressure needs monitoring and intravenous feeding of food or drug administration is required. Examples of clinical situations include treatment of patients with an acute myocardial infraction or patients with shock and myocardial disease of any kind. In such cases, it is necessary to determine whether the heart is failing or an arrhythmia occurs, at any time during the first several days following the heart attack. Such information is reflected in the central venous pressure and also by providing and continuous monitoring of EKG activity. Prevalent causes of death are arrhythmia and heart failure, both of which may require the infusion of different medicines.

EKG activity is normally obtained by electrodes placed on the chest of the patient which presents several disadvantages, notably the interfering with the making of physical examination of the chest area and the generally poor definition of EKG activity inherent in external skin body placement of the electrodes, particularly in the showing of the critically important P waves. A clear showing of the P waves has distinct advantages in acute arrhythmia in distinguishing supraventricular tachycardia from ventricular tachycardia. The best and most dependable sensing and definition of P waves is obtained either in the esophagus or in the superior vena cava. Placement of electrodes in the esophagus is both dangerous and impractical, and is likely in itself to affect undesirable cardiac response. It is, accordingly, a feature and object of the present invention to provide an electrode at the distal end of the central venous catheter which is so positioned as to accurately and dependably sense EKG activity with good resolution of P waves while at the same time not being affected by the infusion of fluid or medication from the distal end of the catheter or by the monitoring of central venous pressure. Normally, the catheter will be inserted into an anticubital vein and threaded up into the superior vena cava for intrathoracic placement and optimum sensing of EKG activity. The catheter may, of course, also be inserted through a femoral vein or subclavian vein and, in each instance, the doctor is able to monitor EKG rhythms during insertion to obtain accurate intrathoracic location with the distal end of the catheter approaching but being kept spaced from the heart. Engagement of the distal end of the catheter with the heart is easily and immediately seen in the EKG display.

Another feature of the present invention is that the electrode placement, in addition to providing superior EKG display with the entire chest area of the patient free for physical examination, also provides an improved and constant electrical contact with the blood adjacent to the heart and thereby avoids completely the heretofore common occurrence of falsely set off alarms. The electrode placement makes the location of the distal end of the catheter always apparent which, in turn, increases the reliability of central venous pressure records.

A critical and dramatic use of the catheter of the present invention is in the emergency and urgency occasioned by a cardiac arrest where restoration of life, if it is to be accomplished, must be done in a very short time, up to about three minutes. In such a situation, the attendant needs to establish respiration, that is, breathe for the patient; monitor the EKG; and obtain access to the central circulation for administration of drugs. A central venous catheter is required since the medicine must reach the heart and not be merely injected into an arm or other part of the body due to lack of blood circulation. At the same time, a continuous electrocardiograph recording is required to signal the administration of the right drugs as conditions change. At present, the procedure is to hook up an EKG apparatus to the patient with the time consuming preparation and placement of the required four electrodes, then inserting a catheter to obtain access to the circulation, and initiating breathing for the patient. The time required to hook up the four leads of the EKG apparatus becomes critical. With the catheter of the present invention, the obtaining of the EKG display and access to the central circulation of the patient is effected with one maneuver, viz., the insertion of the catheter which may be done in a matter of seconds. Changes in size and direction of the P waves provide an immediate indication of the desired entrance of the catheter into the thorax.

Instruments have been designed and used for the sensing of EKG activity within the superior vena cava and within the chambers of the heart itself. The prior art suggests the use of electrodes on specially designed catheters for use by cardiologists in performing heart catheterization where the distal end of the catheter is manipulated into and through the chambers and connecting valve of the heart for removal of blood, inserting of dye, measuring EKG activity, and shocking or pacing the heart. See U.S. Pat. Nos. 3,533,403 and 3,568,660. These catheters are in the nature of special surgical instruments which are inserted into the body for the relatively short period of time required to accomplish the specific objective noted. Such catheter instruments have not been designed or constructed for the placement and use of the present catheter, that is, one which may be left in the body over a protracted period of several days; to provide simultaneous central venous fluid administration and sensing of intrathoracic EKG activity; and simultaneous monitoring of central venous pressure and intrathoracic EKG activity.

The invention possesses other objects and features of advantage, some of which of the foregoing will be set forth in the following description of the preferred form of the invention which is illustrated in the drawing accompanying and forming part of this specification. It is to be understood, however, that variations in the showing made by the said drawing and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawing:

FIG. 1 is a pictorial view of the apparatus of the present invention;

FIG. 2 is a fragmentary, cross-sectional view of a catheter constructed in accordance with the present invention;

FIG. 3 is a cross-sectional view taken substantially on the plane of line 3--3 of FIG. 2;

FIG. 4 is a cross-sectional view taken substantially on the plane of line 4--4 of FIG. 2;

FIG. 5 is a cross-sectional view taken substantially on the plane of line 5--5 of FIG. 2; and

FIG. 6 is a pictorial representation of the present catheter in its position of use in the superior vena cava.

The catheter of the present invention is of the disposable central venous type and is composed of flexible tubing having a length adapted to extend into the superior vena cava and composed of nonreactive material permitting the catheter to remain in place for a protracted period of several days during the course of observation and treatment; an electrical conductor 12 carried by the tubing and extending lengthwise thereof and being electrically insulated from the interior and exterior walls 13 and 14 of the tubing; an electrode 16 connected to conductor 12 and mounted at the exterior surface of the tubing adjacent to but spaced from the distal end 17 thereof; and a terminal 18 for conductor 12 adjacent the proximal end 19 of the tubing for connection by lead 21 to an electrocardiograph 22.

The proximal end 19 of the catheter is provided with an adapter 20 which is, in turn, connected by a length of tubing 25 to the standard three-way manual cock valve 23 which has conduit connections to the base of a manometer tube 24 and to the feed conduit 26 of an I.V. bottle 27. Accordingly, valve 23 may be manually turned between an off position, a second position connecting the manometer 24 to the catheter for reading of central venous pressure, and a third position connecting the catheter to I.V. bottle 27 for infusing fluid through the catheter into the blood stream. Medicine may be injected into the catheter by means of a needle inserted directly into the tubing.

In distinction to the prior art, catheter instruments mentioned in the foregoing which can be tolerated by the body for a very brief period, the catheter of the present invention is constructed of nonreactive material. Nonreactive material is defined as one which the body does not reject or react to. The preferred material is polyethylene. Two other materials, Teflon and Silastic, may also be used. It is essential that the present catheter be made of a substance which the body will tolerate for extended periods of time, several days, without causing an inflamatory reaction.

Another critical feature of the present catheter is the location of electrode 16. It is essential that this electrode be located on the exterior side 14 of the catheter out of contact with the material discharged from the distal end 17 so as to be electrically unaffected thereby. For the same reason, electrode 16 needs be spaced slightly from tip 17 so that a droplet of saline or other material will flow away from the tip without touching electrode 16 and producing an attendant blip on the electrocardiogram. The essential feature of the present invention is that a continuous and accurate EKG display is obtained simultaneously with the infusion into the blood stream of fluid from the distal end of the catheter. Thus, an instantaneous observation may be made of drug administration and EKG activity which is of critical importance in certain instances, as in the treatment of cardiac arrest. Similarly, immediate observation of EKG activity is provided with the introduction of all types of I.V. material. Electrode 16 should be spaced from tip 17 by a distance of about one-eighth inch.

Conductor 12 is here embedded in the wall of tubing 11 and is turned to the outside surface 14 adjacent distal end 17 to provide electrode 16. Alternatively, the outer wall portion may be removed to expose the conductor. In a similar manner, the opposite end of conductor 12 is turned out and electrically connected to the base of terminal 18 secured to the proximal end of the catheter. Terminal 18 is here formed with a circular socket 31 dimensioned for receipt of the conventional pin end on EKG conductor 21 and with a set screw 32 for securing the conductor pin in place. Only a fine wire size is required for conducting the EKG potential. Embedding of conductor 12 in the catheter wall provides the required electrical insulation. The requirement of a minimum wire size enables the use of the invention with standard size central venous pressure catheters, e.g., 22 gauge and 18 gauge, and in usual catheter lengths.

Claims

I claim:

1. In medical apparatus including a central venous catheter, an intravenous feeding supply connected to the proximal end of said catheter, and an electrocardiograph, the improvement comprising:

a central venous catheter composed of nonreactive material having a wall defining a longitudinally extending bore and an opening at the distal end of said catheter and bore for fluid flow longitudinally through said bore toward said distal end and for discharge through said opening;

an electrical conductor carried by and extending lengthwise of said wall and being electrically insulated from the exterior surface of said wall and said bore;

an electrode connected to said conductor and mounted at said exterior surface adjacent to but spaced proximally from said opening; and

a terminal connected to said conductor adjacent said proximal end of said catheter and being connected to said electrocardiograph.

2. An apparatus as defined in claim 1,

said catheter having a length dimensioned for intrathoracic placement of said distal end.

3. An apparatus as defined in claim 1,

a manometer; and

valve means connecting said manometer and source to said proximal end of said catheter for selectively providing central venous fluid administration or central venous pressure determination each while simultaneously displaying EKG activity.

4. A central venous catheter for use with medical apparatus including an intravenous feeding supply adapted for connection to the proximal end of said catheter and an electrocardiograph, comprising:

catheter means for insertion through a vein and into the thoracic cavity of a patient but short of the heart and composed of nonreactive material having a wall defining a longitudinally extending bore and an opening at the distal end of said catheter and bore for fluid flow longitudinally of said bore toward said distal end and for discharge of fluid through said opening, said catheter having a length for disposing said distal end in the patients thorax;

an electrical conductor carried by and extending lengthwise of said wall and being electrically insulated from the exterior surface of said wall and said bore;

an EKG electrode connected to said conductor and mounted at said exterior surface adjacent to but spaced proximally from said opening; and

a terminal connected to said conductor adjacent said proximal end of said catheter and being adapted for connection to said electrocardiograph.

5. A catheter as defined in claim 4, said non-reactive material being polyethylene.

6. A catheter as defined in claim 4, said non-reactive material being Teflon.

7. A catheter as defined in claim 4, said non-reactive material being Silastic.

8. A method comprising:

inserting into a patient's vein the distal end of a central venous catheter having a longitudinally extending bore and an opening at said distal end for fluid flow longitudinally through said bore toward said distal end and for discharge through said opening and an externally mounted electrode adjacent to but spaced proximal to said opening;

advancing said catheter in the direction of blood flow in said vein to position said distal end in the patient's thorax short of the patient's heart and with the patient's blood flowing across said electrode in advance of said opening;

connecting said electrode to an electrocardiogram; and

administering fluid through said catheter to said blood flow while displaying EKG activity as sensed in the patient's blood upstream from the point of fluid addition to said blood flow.