US 3618602 A
Description (OCR text may contain errors)
United States Patent Inventor Robert F. Shaw  References Cited 350 Parnassus Heights, San Francisco, UNITED STATES PATENTS 94117 2,690,178 9/1954 Bickford 128/213 P 2,703,084 3/1955 Tomlinson.... 128/214 med 1969 3,074,410 1/l963 Foster 128/400 Paemed 1971 3,252,623 5/1966 Corbin et al. 222/59 3,274,994 9/1966 Sturm 128/2 FOREIGN PATENTS LIQUID INFUSION INFILTRATION DETECTION 285,777 7/1967 Australia 128/1 APPARATUS AND METHOD 12 Claims, 2 Drawing as. Primary Exammer- Dalton L. Truluck Attorney-A. C. Smith U.S. c1 128/214 E, 222/54' Int. Cl 'A6lm5/00 ABSTRACT: Improved method and means is provided for detecting undesirable infiltration into the perivascular tissue of Field of Search 128/1 ,2, liquid which is normally administered intravenously or intraar- 2l3, 214, 214.2, DIG. l2, DIG. l3; 222/5 terially.
REF. SUPPLY LIQUID INFUSION INFILTRATION DETECTION APPARATUS AND METHOD BACKGROUND OF THE INVENTION Intravenous or intra arterial administration of liquids such as blood, electrolytes, pharmaceuticals, foodstuffs, and the like commonly use a hollow needle or catheter inserted into a superficial artery or vein. However, patient movements may dislodge the needle or catheter from a vein or artery and permit an accumulation of liquid in the perivascular tissue with concomitant discoloration, discomfort and possible destruction of tissue. Presently, detection of this condition requires sufficient infiltration of liquid to produce pain, swelling, discoloration or a cessation of liquid administration due to the buildup of liquid pressure within the local tissue.
SUMMARY OF THE INVENTION In the present invention, the skin temperature in the region about the administration needle or catheter is monitored to provide an early warning of the condition causing liquid infiltration into the perivascular tissue of a patient. Since the liquid being administered to a patient is typically at a lower temperature than normal skin temperature, an undesirable accumulation of the administered liquid produces a resulting lower skin temperature in the region about the accumulation. A detected change in skin beyond a set value may thus be detected and used to terminate liquid administration to the patient and also to provide an alarm indicative of the undesirable liquid infiltration condition.
, DESCRIPTION OF THE DRAWING temperature-responsive transducers in place on the skin surface of a patient.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is shown the arm 9, or other suitable body part of a patient, disposed to receive a liquid-administering needle or catheter 11 in a superficial artery or vein. The-needle or catheter 11 is connected through flexible conduit or tubing 13 to a liquid reservoir 15. Flow control means the detector which may be a signal-controlled valve or tubing clamp in gravity-fed infusion sets or a motor shutoff switch in positive pressure administration sets, or the like, is coupled to the liquid conduit 13 to stop the flow of liquid therethrough in response to a control signal applied thereto on input 19.
A temperature-responsive transducer 21 such as a thermistor or thermocouple, or the like, is disposed preferably on the skin surface about the entrance of the needle or catheter 11 into a vein or artery. The output signal on line 23 from the transducer 21 is thus representative of the skin surface temperature and is applied to the detector means 25 for detection and analysis. The detector means 25 typically includes an amplifier 27 connected to receive the transducer output signal on line 23 and an adjustable threshold detector 29 connected to receive the output of amplifier 27 for producing a control signal at output 31 in response to the amplifier output attaining a selected threshold value.
In operation in this manner, an initial indication of skin surface temperature may be obtained in the region of the entrance of the needle or catheter 11 into a vein or artery of a patient before liquid infusion or administration is commenced. The resultant signal may be stored using conventional signal storage means for comparison with subsequently generated signal values. This initial indication may thus be used as a reference indication against which a lower threshold value of skin temperature may be selected by adjustment of threshold detector 29. Normally, this initial skin temperature at the regionabout the entrance of the needle catheter l1 (and elsewhere on the patients body) is typically about 33 C. if the patient is not in a state of shock and tends to vary with liquid infusion only down to about 3 l C. for common infusion rates of liquids. These liquids are at or about room temperature i.e. about 20?25 C., or colder if the liquids are stored in a refrigerated state (e.g. blood). Thus upon accumulation of the infusion liquid in the perivascular tissue about the region of the entrance of the needle or catheter 11 due, for example, to the needle or catheter 11 becoming dislodged from the vein or artery of the patient, the skin temperature in this region will drop well below the few degrees Centigrade difference which occurs during normal liquid infusion and will closely approach the temperature of the infusion liquid. The threshold detector 29, set to a threshold value of amplified signal from amplifier 27 which is representative of the initial skin temperature, thus produces a control signal at the output 31 which is indicative of abnormal liquid infusion. This control signal may be applied either to an alarm, say, located at a central nursing station, or to the flow-control means 17, or to both the alarm 33 and the flow-control means 17. The liquid infusion is thus terminated automatically by flow-control means 17, or manually as by a nurse responding to the alarm 33 indication or abnormally low skin surface temperature in the entrance region and taking necessary corrective measures.
In another embodiment of the invention, the entrance region temperature, for example, detected by transducer 21, is monitored with respect to a reference signal. For this purpose, an additional temperature transducer 35 may be disposed preferably on the skin surface of the patient 9 at a location which is remote from the entrance region transducer 21. In this embodiment, the amplifier 27 amplifies the difference between signals from the transducers 21 and 35 for application to the threshold detector 29. The advantage of this embodiment is that an initial reading need not be taken to calibrate the threshold detector and also that such differential thermal detection may be used conveniently on patients with abnormal or fluctuating skin temperatures. This may occur in patients who are in a state of shock or who are undergoing hypothermic surgery or therapy and whose skin surface temperatures are lower than normal and also in patients with fevers whose skin temperatures may be higher than normal. The output from threshold detector 29 may also be used in this embodiment to actuate either or both of the alarm 33 and flow-control means 17.
In another embodiment of the present invention, differential thermal detection may be accomplished by comparison of the output signal from transducer 21 with a signal from a reference source of such signal (i.e. instead of signal from transducer 35). This is possible because of reasonable uniformity of skin temperatures encountered at a given location on the body from patient to patient not suffering from the above-mentioned abnormalities.
In FIG. 2 there is shown a pair of transducers 21 and 35 disposed on a length of adhesive tape 41 for positioning on a portion of the body, say, an arm of a patient. The adhesive tape 4] usually has low thermal conductivity and may be disposed to encircle an arm or leg of a patient. Transducers 21 and 35 of FIG. 1 are attached to the inside surface of the tape 41 in position to contact the skin surface of the body part of a patient at spaced locations with the tape in place. Suitable conductors 23 to the transducers may be affixed to the tape 41 to avoid accidental snagging and circuit disconnection from the detector means 25.
Therefore, the present infusion detection apparatus and method provides early indication of liquid infusion into perivascular tissue about the entrance of a liquid conduit into a patients vein or artery. Such early detection may be produced by differential or absolute thermal measurements of skin surface temperature prior to the accumulation of the quantity of liquid commonly required to provide such presently used indications as swelling, skin discoloration, and pam.
1. Infusion-infiltration responsive apparatus for use with liquid-infusion equipment comprising:
liquid-delivery conduit means disposed to be inserted into a blood vessel of a patient for delivering liquid thereto and including control means for stopping liquid infusion into a patient in response to a control signal applied thereto;
a heat-responsive element disposed to be positioned on the skin surface of a patient in the region of the entrance site of a liquid-delivery conduit into a blood vessel of the patient for producing an output indicative of the temperature of skin of the patient in said region; and
circuit means coupled to the output of said element and to said control means for applying a control signal thereto to stop liquid infusion into the patient in response to said output attaining a selected value.
2. Infusion-infiltration responsive apparatus as in claim 1 wherein:
said control means includes pinching apparatus disposed about a portion of conduit of the liquid-delivery conduit means for occluding the conduit to stop the flow of liquid therethrough in response to said control signal applied to said control means.
3. lnfusion-infiltration responsive apparatus as in claim 1 wherein:
said liquid-delivery conduit means includes motor-driven liquid-pumping means; and
said control means is coupled to said liquid-pumping means for stopping the pumping of liquid thereby in response to said control signal applied to said control means.
4. Infusion-infiltration responsive apparatus as in claim 1 wherein:
said circuit means includes threshold detection means for producing said control signal only in response to said output attaining a preselected value.
5. Infusion-infiltration responsive apparatus as in claim 4 wherein: said circuit means includes a source of a reference signal which is representative of a selected absolute temperature of the skin surface of a patient; and
said threshold detection means produces said control signal only in response to a selected algebraic combination of the output from said element and said reference signal attaining a predetennined relationship.
6. lnfusion-infiltration responsive apparatus as in claim 4 wherein:
said circuit means includes signal storage means for storing a signal representative of the temperature of the skin of a patient in the region of said entrance site prior to liquid infusion into a blood vessel of the patient; and
said circuit produces said control signal in response to the difference between the stored signal prior to liquid infusion and the output of said element following commencement of liquid-infusion attaining a predetermined value.
7. infusion-infiltration responsive apparatus as in claim 1 comprising:
a source of reference signal which is representative of the surface temperature of the skin of a patient at a location remote from said site; and
said circuit means includes threshold response means which produces said control signal in response to said output decreasing below said reference signal by a selected value.
8. Infusion-infiltration responsive apparatus as in claim 7 wherein:
said source includes an auxiliary heat-responsive element disposed to be positioned at a location on the skin surface of a patient remote from said site for producing said reference signal representative of the skin surface temperature at said location; and
said threshold responsive means includes a differential detector which responds to the difference between said output and said reference signal for producing said control signal in response to said difference attaining a selected value.
9. The method of liquid-infusion administration comprising the steps of:
placing a liquid-infusion delivery conduit into a blood vessel of a patient for delivering an infusion liquid into the blood vessel of the patient; and
simultaneously sensing the skin temperature in the region of the entrance site of the conduit into the blood vessel for detecting changes in the skin temperature in said region associated with the liquid infiltration to control liquid infusion into the blood vessel in response to changes in said skin temperature beyond a selected value.
10. The method of liquid-infusion administration as in claim 9 comprising the additional step of:
discontinuing delivery of the infusion liquid to the blood vessel of the patient in response to the temperature sensed in said region attaining a selected value.
1 l. The method of liquid infusion administration as in claim 10 comprising the additional step of sensing the temperature in said region of the entrance site prior to the infusion of liquid and wherein the step of discontinuing delivery of the infusion liquid is performed in response to the temperature sensed in said region following commencement of liquid infusion deviating by a preselected amount from the temperature sensed prior to infusion of liquid.
12. The method of liquid infusion administration as in claim 10 wherein the step of discontinuing delivery of the infusion liquid is performed by simultaneously sensing the skin temperature of the patient at a location remote from said entrance site; and
discontinuing the delivery of the infusion liquid in response to the difference between the temperatures about said entrance site and at said location attaining a selected value.
I k t i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,618, 602 Dated November 9, 1971 Inventor(s) Robert F. Shaw It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 1, line 49, after "means" delete "the detector" and insert l7,
Signed and Scaled this Arrest:
RUTH C. MASON C. MARSHALL DANN Arresting Officer (ummissiuner ufPatenrs and Tradcmarkx