Abstract:
A venipuncture device may be used for assisting a healthcare provider identify and locate a blood vessel in a patient. According to embodiments, heat is applied to a selected venipuncture site on the patent&#39;s limb. A pressure cuff constricts the limb proximal to the venipuncture site, thereby partially occluding blood flow through the blood vessel and engorging the blood vessel and making it more visible to the healthcare provider. The healthcare provider may then carry out various operations on the patient, including but not limited to drawing blood and insertion of an intravenous line.

Description:
BACKGROUND 
     Technical Field 
     The present disclosure relates generally to venipuncture. In particular, the present disclosure relates to methods and devices to assist in identifying and/or locating blood vessels in a patient. 
     Description of Related Art 
     Under various circumstances, a healthcare provider may attempt to locate and/or identify a blood vessel of a patient for several various reasons. For example, the healthcare provider may need to find a blood vessel to collect a blood sample from the patient or to insert an intravenous (IV) line into the patient. 
     Sometimes, finding a suitable blood vessel in a patient poses some difficulty. Some patients may have blood vessels that are not easily visible. Some patients may have fat layers that obscure the blood vessels. Techniques that may be typically carried out to identify a blood vessel include use of an elastic or other type of strip as a tourniquet to temporarily partially block blood flow through the vessel, which may engorge the vessel, thereby aiding the healthcare provider in locating it. Such strips are typically tightened around a patient&#39;s limb by manually applying tension to the strip and fastening and/or tying the strip to itself. 
     SUMMARY 
     In one embodiment, a venipuncture device is disclosed. The venipuncture device includes a heating element and an inflatable cuff. The cuff is adapted to form a loop around a selected limb of the patient. The cuff operates to partially occlude a blood vessel of the patient while the cuff is inflated. The heating element operates to apply heat to a venipuncture site on the limb distal to the cuff. 
     In another embodiment, a method of identifying a blood vessel in a patient is disclosed. The method includes positioning a heat source at a selected venipuncture site on a limb of the patient, applying heat to the venipuncture site, wrapping a cuff having an inflatable chamber around the limb proximal to the venipuncture site, inflating the chamber, thereby partially occluding the blood vessel, and removing the heat source from the venipuncture site. 
     The present disclosure will now be described more fully with reference to the accompanying drawings, which are intended to be read in conjunction with both this summary, the detailed description, and any preferred or particular embodiments specifically discussed or otherwise disclosed. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of illustration only so that this disclosure will be thorough, and fully convey the full scope of the invention to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. 
         FIG. 1  depicts an embodiment of a venipuncture device according to an embodiment of the present disclosure; 
         FIG. 2  depicts an embodiment of a venipuncture device and vital signs cart according to an embodiment of the present disclosure; 
         FIGS. 3A-3C  depict an application of a venipuncture device according to embodiments of the present disclosure; and 
         FIG. 4  depicts an application of a venipuncture device to a patient&#39;s forearm according to embodiments of the present disclosure. 
     
    
    
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present disclosure. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present disclosure. 
     DETAILED DESCRIPTION 
     In the following description, reference is made to exemplary embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the concepts disclosed herein, and it is to be understood that modifications to the various disclosed embodiments may be made, and other embodiments may be utilized, without departing from the spirit and scope of the present disclosure. The following detailed description is, therefore, not to be taken in a limiting sense. 
     Reference throughout this specification to “one embodiment,” “an embodiment,” “one example,” or “an example” means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” “one example,” or “an example” in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combinations and/or sub-combinations in one or more embodiments or examples. 
     Embodiments of the present disclosure include methods and devices for facilitating blood vessel engorgement in a patient by applying pressure and heat to a limb of the patient at a venipuncture site. As used herein, the term “patient” includes, but is not limited to, a person or animal that is the subject of medical care, attention, and/or testing. As would be understood by a person of ordinary skill in the art having the benefit of the present disclosure, the patient may be virtually any mammal, including a human, or another type of animal. 
     Referring to  FIG. 1 , embodiments of the present disclosure comprise a venipuncture device  100 . According to various embodiments, venipuncture device  100  comprises an inflatable cuff  110  and a heat pad  120 . In an embodiment, cuff  110  comprises one or more internal chambers and an outer covering. Cuff  110  comprises fasteners  112  adapted to form cuff  110  into a loop around an appendage of the patient. In one embodiment, fasteners  112  comprise hook-and-loop pads adapted to secure to surfaces of cuff  110 , thereby forming cuff  110  into a loop. In another embodiment, fasteners  112  comprise adhesive. In alternative embodiments, fasteners  112  comprise other material and/or mechanisms adapted to hold cuff  110  in a loop wrapped around a patient&#39;s limb. 
     In embodiments, cuff  110  has a length proportionate to a patent&#39;s limb circumference, such that cuff  110  may wrap around the limb and allow secure fasteners  112  to secure to surface of cuff  110 . Various lengths of cuff  110  may be provided so that cuff  110  has an appropriate length to exceed the circumference of a patient&#39;s limb, thereby leaving an overlap of cuff material to allow contact between fasteners  112  and surface of cuff  110 . For example, cuff  110  may be provided in lengths appropriate for the following categories of human patients: neonatal, pediatric, adult, adult large, and adult thigh. As examples, but not to be taken in a limiting sense, the foregoing categories of human patients may correspond to the following respective lengths of cuff  110 : 6-11 cm, 10-19 cm, 18-26 cm, 25-43 cm, and 42-54 cm. According to some sizing systems, cuff  110  may be provided according to standard numerical sizes, for example size 6, 7, 8, 9, 10, 11, 12, or 13. Cuff  110  may be manufactured in other selected lengths as may be dictated by particular patient sizes or other circumstances. 
     In embodiments, the internal chambers have flexible and/or expandable walls. The internal chambers may be filled with air or other fluid to constrict cuff  110  around a patient&#39;s limb to a selected pressure. Air may enter the internal chambers from tube  114  and fill the cuff  110  to a selected pressure. Connector  116  comprises a fitment for attaching tube  114  to a pressurized air source. In embodiments, tube  114  comprises a compliant, flexible material such as thermoplastic polyurethane. In other embodiments, tube  114  is manufactured from other suitable materials. 
     In embodiments, cuff  110  has a width appropriately large so that while cuff  110  is wrapped around a patient&#39;s limb and while the internal chambers are inflated, sufficient pressure may be exerted upon the patient&#39;s limb to partially occlude a blood vessel in the patient&#39;s limb. 
     According to various embodiments of the present disclosure, heat pad  120  comprises one or more internal heating elements within a flexible outer covering. Embodiments of heat pad  120  comprise fasteners  122  adapted to form heat pad  120  into a loop around an appendage of the patient. In one embodiment, fasteners  122  comprise hook-and-loop pads adapted to secure to surfaces of heat pad  120 , thereby forming heat pad  120  into a loop. In another embodiment, fasteners  122  comprise adhesive. In alternative embodiments, fasteners  122  comprise other material and/or mechanisms adapted to hold heat pad  120  in a loop wrapped around a patient&#39;s limb. 
     In embodiments, heat pad  120  has a length proportionate to a patent&#39;s limb circumference to wrap around the limb and secure fasteners  122  together. Various lengths of heat pad  120  may be provided so that heat pad  120  has an appropriate length to exceed the circumference of a patient&#39;s limb, thereby leaving an overlap of material to allow contact between fasteners  122  and surface of heat pad  120 . According to some embodiments, multiple heat pads  120  of various lengths may be provided according to the circumference of a particular patient&#39;s limb. In one embodiment, cuff  110  and heat pad  120  have approximately the same length. 
     Embodiments of heat pad  120  comprise electrical cord  124  having plug  126  for connection of heat pad  120  to a power source. Embodiments of the present disclosure further comprise a thermo regulator with an automatic shut off function in order to not exceed a selected upper temperature limit. For example, the upper limit may selectively be set at 86 degrees Celsius so as to not cause damage to the skin of a patient. 
     Cuff  110  and heat pad  120  may be held together by connector tab  130 . In an embodiment, connector tab  130  comprises a snap fastener. In alternative embodiments, other types of fasteners and/or adhesives are adapted to hold cuff  110  and heat pad  120  together. 
     Referring to  FIG. 2 , embodiments of venipuncture device  100  may be connected to a vital signs cart  200 . In such embodiments, vital signs cart  200  includes a pressurized air source for inflating cuff  110 . Embodiments of vital signs cart  200  further include an electrical power source for supplying current to heat pad  120  for heating thereof. In various embodiments, vital signs cart  200  includes a control interface for selecting a pressure to be applied to cuff  110  and/or temperature to be applied to heat pad  120 . In some embodiments, vital signs cart  200  includes a memory and/or computer-readable instructions to direct a series of operations including: measuring the patient&#39;s blood pressure, determining a target pressure for optimal blood vessel engorgement, activating heat pad  120  to a selected temperature, and inflating cuff  110  to the target pressure. 
     According to embodiments, vital signs cart  200  may be powered by a wall outlet, a battery, a combination of both, or by other power sources. Vital signs cart may include an onboard air compressor for inflation of cuff  110 . Alternatively, an external source may feed pressurized air into cuff  110  via tube  114 . 
     In operation, venipuncture device  100  may be used to assist a healthcare provider in identifying and/or locating blood vessels in a patient&#39;s extremity. For example, venipuncture device  100  may assist the healthcare provider in locating a blood vessel on the patient&#39;s leg and/or arm. Referring to  FIG. 3A , a healthcare provider may first place the patient&#39;s limb  300  in contact with venipuncture device  100 , positioning cuff  110  proximal to a targeted area  310  on the limb. For example, as depicted in  FIG. 3A , the selected patient&#39;s blood vessel is the patient&#39;s median cubital vein. The cuff  110  has been positioned proximal to the venipuncture site  310 . In embodiments, the healthcare provider visually examines the venipuncture site  310  to determine if the targeted vein is obvious. If the vein is not sufficiently visible for the healthcare provider to puncture, a decision to use cuff  110 , heat pad  120 , or both on the patient may be made. 
     Referring now to  FIG. 3B , cuff  110  and heat pad  120  are wrapped around the patient&#39;s limb  300  and secured by fasteners  112 ,  122 , forming a snug fit. As depicted, heat pad  120  is wrapped around the venipuncture site  310  and the surrounding area on the patient&#39;s limb  300 . 
     In the event of a decision by the healthcare provider that the patient&#39;s vein is not sufficiently obvious, heat may be applied to the venipuncture site to engorge the vein. Electrical current may be transmitted along cord  124  thereby powering heat pad  120  to a target temperature and applying heat to the patient&#39;s limb  300 . In an embodiment, the target temperature of heat pad  120  ranges from 76 degrees Celsius to 82 degrees Celsius. In one embodiment, heat is applied for a period of five to ten minutes to the venipuncture site  310 . In other embodiments, the healthcare provider may determine that heat application is not needed. In such circumstances, the heat pad  120  may be separated at tab  130  from pressure cuff  110  and cuff  110  may be wrapped around the patient&#39;s limb  300  proximal to the venipuncture site  310  without heat pad  120 . 
     Following placement and wrappage of cuff  110 , pressurized air may be passed though tube  114  to inflate cuff  110 . According to embodiments, cuff  110  may be inflated to a targeted pressure in order to partially occlude the patient&#39;s targeted blood vessel. In one embodiment, the pressure target is the patient&#39;s diastolic blood pressure. 
     In other embodiments, the pressure target is slightly less than the patient&#39;s diastolic blood pressure. In embodiments, the pressure target is determined as a percentage of the patient&#39;s measured diastolic blood pressure. In one embodiment, the pressure target is 99% of the patient&#39;s measured diastolic blood pressure. In another embodiment, the pressure target is 95% of the patient&#39;s measured diastolic blood pressure. In another embodiment, the pressure target is 90% of the patient&#39;s measured diastolic blood pressure. As an illustrative example, if a patient&#39;s blood pressure is measured to be 75 mm Hg, the pressure target can be calculated as 95% of 75 mm Hg, which is 71.3 mm Hg. 
     In some embodiments, the pressure target is determined as an absolute difference from the patient&#39;s measured diastolic blood pressure. In one embodiment, the pressure target is 1 mm Hg less than the patient&#39;s measured diastolic blood pressure. In another embodiment, the pressure target is 3 mm Hg less than the patient&#39;s measured diastolic blood pressure. In another embodiment, the pressure target is 5 mm Hg less than the patient&#39;s measured diastolic blood pressure. As another illustrative example, if a patient&#39;s blood pressure is measured to be 75 mm Hg, the pressure target can be calculated as 3 mm Hg less than 75 mm Hg, which is 72 mm Hg. 
     The patient&#39;s diastolic blood pressure may be measured manually by a healthcare provider, for example by using a sphygmomanometer and/or other known methods. Alternatively, the patient&#39;s diastolic blood pressure may be measured by using cuff  110  as a sphygmomanometer inflated either by pressured air from vital signs cart  200  or a secondary bulb connected to tube  114 . In embodiments, vital signs cart  200  may effectively utilize cuff  110  to operate as an automated sphygmomanometer to measure the patient&#39;s diastolic blood pressure. 
     Referring now to  FIG. 3C , heat pad  120  may be unwrapped to expose the venipuncture site  310  and give the healthcare provider access thereto. As shown, the patient&#39;s median cubital vein  320  is now visibly engorged as a result of the heat and constriction, which may allow the healthcare provider to identify and puncture it with relative ease. The healthcare provider can then draw the patient&#39;s blood, pass an intravenous line into the targeted blood vessel, or carry out other desired actions on the patient. Cuff  110  may be left in place at the selected pressure while carrying out such actions, or may be partially or completely deflated. 
     As stated above, venipuncture device  100  may be applied to various sites on a patient&#39;s limb. Referring now to  FIG. 4 , the patient&#39;s basilic vein has been selected as the venipuncture site  410  in an illustrative example. As such, cuff  110  is placed proximal to the venipuncture site  410  and heat pad  120  is placed at and distal to the venipuncture site  410 . Heat and/or pressure may then be administered to the venipuncture site to engorge the selected vein similar to the manner described above. 
     Although the present disclosure is described in terms of certain preferred embodiments, other embodiments will be apparent to those of ordinary skill in the art, given the benefit of this disclosure, including embodiments that do not provide all of the benefits and features set forth herein, which are also within the scope of this disclosure. It is to be understood that other embodiments may be utilized, without departing from the spirit and scope of the present disclosure.