CA1083090A - Disposable cold pack for blood specimen - Google Patents
Disposable cold pack for blood specimenInfo
- Publication number
- CA1083090A CA1083090A CA247,167A CA247167A CA1083090A CA 1083090 A CA1083090 A CA 1083090A CA 247167 A CA247167 A CA 247167A CA 1083090 A CA1083090 A CA 1083090A
- Authority
- CA
- Canada
- Prior art keywords
- envelope
- cold pack
- insulation layer
- water
- ammonium nitrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
DISPOSABLE COLD PACK FOR BLOOD SPECIMEN
Abstract of the Disclosure A disposable cold pack for cooling and storing a sample of freshly drawn blood at 28° to 40°F. for 45 minutes has an outer flexible insulation layer and a pair of sealed flexible plastic envelopes, one within the other and the outer one secured to the insulation, the inner envelope being filled with water and frangible, the outer one containing ammonium.
nitrate in a ratio to water from 1.24:1 to 1.26:1 by weight, and a closure for securing the pack in folded position around the sample container.
Abstract of the Disclosure A disposable cold pack for cooling and storing a sample of freshly drawn blood at 28° to 40°F. for 45 minutes has an outer flexible insulation layer and a pair of sealed flexible plastic envelopes, one within the other and the outer one secured to the insulation, the inner envelope being filled with water and frangible, the outer one containing ammonium.
nitrate in a ratio to water from 1.24:1 to 1.26:1 by weight, and a closure for securing the pack in folded position around the sample container.
Description
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This invention relates to a disposable cold pack for cooling and storing a container filled with a sample of freshly drawn blood for subsequent analysis.
In conducting certain analyses of samples of freshly drawn arterial blood, it is essential for optimum accuracy to carry out the analyses without delay, because when the sample is allowed to stand for more than a few minutes at room temperature, changes in composition occur which render the subsequent analy-sis inaccurate. It is frequently impossible to arrange for the necessary analytical equipment to be present at the location where the blood sample is drawn and so the practice has devel-oped of immediately immersing the sample in its container, which is usually the sealed plastic or glass barrel of a syringe, in a -bucket of ice or of a water-ice mixture in order to chill it as rapidly as possible and to maintain it at a temperat~re slightly above freezing while it is transported in the ice bucket to the anaIytical equipment. The elapsed time between the drawing of the sample and t~e beginning of analysis usually does not exceed 45 minutes. It is important that the temperature of the blood sample be maintained below 40F. after it has been drawn because changes in composition occur fairly rapidly when the temperature of the blood sample exceeds that level. On the other hand, it ;
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is essential that the temperature of the sample not be reduced below 28QF. in order to avoid irreversible changes in cell ;
structure caused by freezing. In the case of an ice bucket, tests have shown that a period of 7 minutes is required to lower the temperature of the usual 5 cc. blood sample from body :
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This invention relates to a disposable cold pack for cooling and storing a container filled with a sample of freshly drawn blood for subsequent analysis.
In conducting certain analyses of samples of freshly drawn arterial blood, it is essential for optimum accuracy to carry out the analyses without delay, because when the sample is allowed to stand for more than a few minutes at room temperature, changes in composition occur which render the subsequent analy-sis inaccurate. It is frequently impossible to arrange for the necessary analytical equipment to be present at the location where the blood sample is drawn and so the practice has devel-oped of immediately immersing the sample in its container, which is usually the sealed plastic or glass barrel of a syringe, in a -bucket of ice or of a water-ice mixture in order to chill it as rapidly as possible and to maintain it at a temperat~re slightly above freezing while it is transported in the ice bucket to the anaIytical equipment. The elapsed time between the drawing of the sample and t~e beginning of analysis usually does not exceed 45 minutes. It is important that the temperature of the blood sample be maintained below 40F. after it has been drawn because changes in composition occur fairly rapidly when the temperature of the blood sample exceeds that level. On the other hand, it ;
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is essential that the temperature of the sample not be reduced below 28QF. in order to avoid irreversible changes in cell ;
structure caused by freezing. In the case of an ice bucket, tests have shown that a period of 7 minutes is required to lower the temperature of the usual 5 cc. blood sample from body :
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temperature (99F.) to 36F. with crushed ice alone (no water), and 4 minutes with a water-ice mixture, in room temperature (76F.) surroundings.
Although disposable cold packs such as the one des-cribed in Robbins et al U.S. Patent 2,925,719 have been available, they have failed to provide for chilling at maximum rate of speed without risk of cooling below the critical temperature of 28F., while at the same time ensuring a temperature below 40F. for a sufficiently long period of time. The present invention provides a disposable cold pack which can readily be activated without special equipment and which is effective to chill rapidly a con-tainer filled with a freshly drawn sample of blood from body tem- ;
perature to a temperature within the range from 28 to 40F. and to maintain it within that temperature range for at least 45 min-utes. Tests have shown that the preferred embodiment of the present invention is capable of cooling the usual 5 cc. blood sample from 99F.to 36F. within 2 minutes in room temperature (76F.) surroundings. The invention provides a disposable cold pack for cooling and storing a container filled with a sample of ~reshly drawn blood comprising an outer flexible insulation layer comprising foam plastic material, a first sealed flexible enve-lope of plastlc material secured adjacent one face of the insula-tion layer, a supply of dry, solid ammonium nitrate disposed within the first envelope, a second sealed and frangible envelope ~-containing a supply of water disposed within the first envelope ~
,. .,~ -and arranged to be broken by pressure applied externally to the ---first envelope to release the supply of water into the supply of ammonium nitrate within the first envelope to activate the cold ~:
pack, the weight ratio of ammonium nitrate to water being from 1.24:1 to 1.26:1 and a closure member having a pressure-sensi-tive adhesive face secured to the insulation layer for releas-ably maintaining the cold pack in folded position with the insu-lation layer outermost and with the sample container in contact with the first envelope, the cold pack being capable of chill-ing the blood sample rapidly and of maintaining it at a tempera-ture of 28 to 40F. for at least 45 minutes after activation in room temperature surroundings. In a preferred embodiment, the insulation layer includes a continuous film of flexible plastic bonded to the foam plastic material at the face adjacent the first envelope, and the first envelope is heat sealed along at .: : .
least one marginal portion thereof to the insulation layer. In the preferred embodiment, the invention further features an insulation layer of rectangular configuration which is not only coextensive in area with one face of the rectangular first enve . -lope but extends substantially beyond at least one margin of the first envelope to provide a flap, the closure member being -:
secured to the margin of the flap remote from the first envelope.
In the usual case where the size of the blood sample is approxi-mately 5 cc., the total weight of water and ammonium nitrate must be from 180 to 200 grams for best results.
Other features and advantages of the invention will appear from the drawing and from the detailed description which follows. -In the drawing~
Fig. 1 is an isometric view showing a preferred embodi- -ment o the invention before activation and use;
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temperature (99F.) to 36F. with crushed ice alone (no water), and 4 minutes with a water-ice mixture, in room temperature (76F.) surroundings.
Although disposable cold packs such as the one des-cribed in Robbins et al U.S. Patent 2,925,719 have been available, they have failed to provide for chilling at maximum rate of speed without risk of cooling below the critical temperature of 28F., while at the same time ensuring a temperature below 40F. for a sufficiently long period of time. The present invention provides a disposable cold pack which can readily be activated without special equipment and which is effective to chill rapidly a con-tainer filled with a freshly drawn sample of blood from body tem- ;
perature to a temperature within the range from 28 to 40F. and to maintain it within that temperature range for at least 45 min-utes. Tests have shown that the preferred embodiment of the present invention is capable of cooling the usual 5 cc. blood sample from 99F.to 36F. within 2 minutes in room temperature (76F.) surroundings. The invention provides a disposable cold pack for cooling and storing a container filled with a sample of ~reshly drawn blood comprising an outer flexible insulation layer comprising foam plastic material, a first sealed flexible enve-lope of plastlc material secured adjacent one face of the insula-tion layer, a supply of dry, solid ammonium nitrate disposed within the first envelope, a second sealed and frangible envelope ~-containing a supply of water disposed within the first envelope ~
,. .,~ -and arranged to be broken by pressure applied externally to the ---first envelope to release the supply of water into the supply of ammonium nitrate within the first envelope to activate the cold ~:
pack, the weight ratio of ammonium nitrate to water being from 1.24:1 to 1.26:1 and a closure member having a pressure-sensi-tive adhesive face secured to the insulation layer for releas-ably maintaining the cold pack in folded position with the insu-lation layer outermost and with the sample container in contact with the first envelope, the cold pack being capable of chill-ing the blood sample rapidly and of maintaining it at a tempera-ture of 28 to 40F. for at least 45 minutes after activation in room temperature surroundings. In a preferred embodiment, the insulation layer includes a continuous film of flexible plastic bonded to the foam plastic material at the face adjacent the first envelope, and the first envelope is heat sealed along at .: : .
least one marginal portion thereof to the insulation layer. In the preferred embodiment, the invention further features an insulation layer of rectangular configuration which is not only coextensive in area with one face of the rectangular first enve . -lope but extends substantially beyond at least one margin of the first envelope to provide a flap, the closure member being -:
secured to the margin of the flap remote from the first envelope.
In the usual case where the size of the blood sample is approxi-mately 5 cc., the total weight of water and ammonium nitrate must be from 180 to 200 grams for best results.
Other features and advantages of the invention will appear from the drawing and from the detailed description which follows. -In the drawing~
Fig. 1 is an isometric view showing a preferred embodi- -ment o the invention before activation and use;
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Fig. 2 is a view in cross-section on an enlarged scale showing the embodiment of Fig. l before activation and use;
Fig. 3 is a view in cross-section showing the device after activation with the sample container enfolded within it;
and Fig. 4 is a view in cross-section taken along line 4-4 of Fig. 3.
The embodiment shown in the drawing includes an outer generally rectangular flexible insulation layer lO of foam plastic material such as a foamed polyethylene material sold under the trademark Microfoam approximately l/16 inch thick laminated to an inner plastic film 12 of polyethylene approximately 2 mils thick, the two members lO and 12 being coextensive in area and bonded together throughout their extent to serve as a laminated insulat- ~
ing layer. A sealed rectangular flexible envelope 14 formed of -two sheets of 2 mil polyethylene film 16, 18 folded together is ;~
secured to film 12 and foam plastic layer lO by heat sealing in zones 20, 22 and 24 along three margins of the rectangular enve-lope 50 that the face of the envelope 14 is adjacent the face of :~
the insulating layer. Disposed within envelope 14 is a second ~ ~ -sealed envelope 26 formed of a single layer of 2 mil polyethylene film or made up of composite layers of materials (inner layer of polyethylene laminated to a slitted polyester film, sold under the trademark Myler, and outer layer of like Mylar film coated with Saran polyvinylidene chloride) and filled with a supply 28 of water. The water-containing envelope 26, because of its relatively thin walls, is readily broken or ruptured by pressuxe applied externally of outer envelope 14 without breaking the walls of the outer envelope. Also disposed
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Fig. 2 is a view in cross-section on an enlarged scale showing the embodiment of Fig. l before activation and use;
Fig. 3 is a view in cross-section showing the device after activation with the sample container enfolded within it;
and Fig. 4 is a view in cross-section taken along line 4-4 of Fig. 3.
The embodiment shown in the drawing includes an outer generally rectangular flexible insulation layer lO of foam plastic material such as a foamed polyethylene material sold under the trademark Microfoam approximately l/16 inch thick laminated to an inner plastic film 12 of polyethylene approximately 2 mils thick, the two members lO and 12 being coextensive in area and bonded together throughout their extent to serve as a laminated insulat- ~
ing layer. A sealed rectangular flexible envelope 14 formed of -two sheets of 2 mil polyethylene film 16, 18 folded together is ;~
secured to film 12 and foam plastic layer lO by heat sealing in zones 20, 22 and 24 along three margins of the rectangular enve-lope 50 that the face of the envelope 14 is adjacent the face of :~
the insulating layer. Disposed within envelope 14 is a second ~ ~ -sealed envelope 26 formed of a single layer of 2 mil polyethylene film or made up of composite layers of materials (inner layer of polyethylene laminated to a slitted polyester film, sold under the trademark Myler, and outer layer of like Mylar film coated with Saran polyvinylidene chloride) and filled with a supply 28 of water. The water-containing envelope 26, because of its relatively thin walls, is readily broken or ruptured by pressuxe applied externally of outer envelope 14 without breaking the walls of the outer envelope. Also disposed
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within outer envelope 14 is a supply 30 of dry solid ammonium nitrate in finely divided form. Preferably, air is evacuated from outer envelope 14 before heat sealing is completed so that the walls of the two envelopes will abut each other to facili-tate rupturing of the inner envelope by external pressure.
Envelope 14 e~tends over only a portion of the length of members 10 and 12 so that the latter extends beyond the heat sealed mar-gin of envelope 14 to form a flap 32. To the margin of flap 32 remote from envelope 14 is secured as a closure member one or ~
more lengths of pressure sensitive adhesive tape 34 provided with -;
a removable temporary protective cover sheet 36 over its exposed aclhesive face. Alternatively, a rubber band or piece of string, -a band of cohesive (self-adherent) material or other mechanical fastening may be used in place of adhesive tape 34.
Although envelope 14 and insulation layer 10 are rec-tangular in configuration in the embodiment described above, it will be appreciated that other shapes such as oval may also be used. Indeed, it is possible, although less convenient, to have the insulation layer unattached to the outer en~elope 14 but instead in the form of a separate flexible sheet together with a closure mèmber; if desired, the separate insulation layer may be preformed into a cylindrical chamber or a box of appropriate dimensions. ~-In order to achieve the desired results, it is essen-tial that the ratio vf ammonium nitrate to water be from 1.24~
to 1.26:1 by weight. In the case of a blood sample which is 5 ;
cc. by volume, the size sample which is usually employed, the weight of ammonium nitrate and water should be from 180 to 200 grams for best results.
"' :"
within outer envelope 14 is a supply 30 of dry solid ammonium nitrate in finely divided form. Preferably, air is evacuated from outer envelope 14 before heat sealing is completed so that the walls of the two envelopes will abut each other to facili-tate rupturing of the inner envelope by external pressure.
Envelope 14 e~tends over only a portion of the length of members 10 and 12 so that the latter extends beyond the heat sealed mar-gin of envelope 14 to form a flap 32. To the margin of flap 32 remote from envelope 14 is secured as a closure member one or ~
more lengths of pressure sensitive adhesive tape 34 provided with -;
a removable temporary protective cover sheet 36 over its exposed aclhesive face. Alternatively, a rubber band or piece of string, -a band of cohesive (self-adherent) material or other mechanical fastening may be used in place of adhesive tape 34.
Although envelope 14 and insulation layer 10 are rec-tangular in configuration in the embodiment described above, it will be appreciated that other shapes such as oval may also be used. Indeed, it is possible, although less convenient, to have the insulation layer unattached to the outer en~elope 14 but instead in the form of a separate flexible sheet together with a closure mèmber; if desired, the separate insulation layer may be preformed into a cylindrical chamber or a box of appropriate dimensions. ~-In order to achieve the desired results, it is essen-tial that the ratio vf ammonium nitrate to water be from 1.24~
to 1.26:1 by weight. In the case of a blood sample which is 5 ;
cc. by volume, the size sample which is usually employed, the weight of ammonium nitrate and water should be from 180 to 200 grams for best results.
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In using the cold pack, the barrel of the syringe into which the blood sample is drawn in the usual manner is sealed by inserting the end of the needle into a rubber stopper, or else the needle is first disconnected and discarded, after which the barrel is sealed. Inner envelope 26 is ruptured by manipulation of the cold pack so that the water is mixed with the ammonium nitrate, and barrel 38 of the syringe filled with the blood sam-ple is then placed in the position indicated by printed design 40 on the face of envelope 14, and the envelope, together with the outer insulating layer, is folded upon itself to envelop the syringe barrel as shown in Figs. 3 and 4. Temporary protective sheet 36 is stripped from the adhesive tape and the latter is pressed against the exposed face of insulation layer 10 as shown in Figs. 3 and 4 to maintain the cold pack releasably in folded position snugly enveloping the syringe barrel 38. In the case where the insulatlng layer is separate from the envelope 14, it may be wrapped around the envelope simultaneously with envelop- ~-ment of the syringe barrel 38 by the envelope or subsequently ~hereto, and secured in place by a closure member. In the case where the separate insulating layer is preformed into a container or box, the insulating layer can be rigid or stiff instead of flexible if desired and the container or box is of such size that the rolled-up envelope 14 enclosing syringe barrel 38 is a snug fit within lt, so that after insertion the envelope is main-tained in rolled-up condition around the syringe barrel.
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In using the cold pack, the barrel of the syringe into which the blood sample is drawn in the usual manner is sealed by inserting the end of the needle into a rubber stopper, or else the needle is first disconnected and discarded, after which the barrel is sealed. Inner envelope 26 is ruptured by manipulation of the cold pack so that the water is mixed with the ammonium nitrate, and barrel 38 of the syringe filled with the blood sam-ple is then placed in the position indicated by printed design 40 on the face of envelope 14, and the envelope, together with the outer insulating layer, is folded upon itself to envelop the syringe barrel as shown in Figs. 3 and 4. Temporary protective sheet 36 is stripped from the adhesive tape and the latter is pressed against the exposed face of insulation layer 10 as shown in Figs. 3 and 4 to maintain the cold pack releasably in folded position snugly enveloping the syringe barrel 38. In the case where the insulatlng layer is separate from the envelope 14, it may be wrapped around the envelope simultaneously with envelop- ~-ment of the syringe barrel 38 by the envelope or subsequently ~hereto, and secured in place by a closure member. In the case where the separate insulating layer is preformed into a container or box, the insulating layer can be rigid or stiff instead of flexible if desired and the container or box is of such size that the rolled-up envelope 14 enclosing syringe barrel 38 is a snug fit within lt, so that after insertion the envelope is main-tained in rolled-up condition around the syringe barrel.
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Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOW
1. A disposable cold pack for cooling and storing a container filled with a sample of freshly drawn blood comprising a temperature regulation means which comprises the elements of a first sealed flexible envelope of plastic ma-terial, a supply of dry solid ammonium nitrate disposed within said first envelope, a second sealed and frangible envelope containing a supply of water disposed within said first envelope and arranged to be broken by pressure applied externally to said first envelope to release said supply of water into said supply of ammonium nitrate within said first sealed envelope to activate said cold pack, the weight ratio of ammonium nitrate to water being from 1.24:1 to 1.26:1, the total weight of ammonium nitrate and water being from 180 to 200 grams, the elements of said temperature regulating means cooperatively functioning, upon the breaking of said second envelope, to cool said sample to a temperature low enough to avoid composition changes therein, but high enough to avoid freezing thereof, for a period of at least 45 minutes, said cold pack being adapted to be folded around said sample container with the container in contact with said first envelope.
2. A cold pack as claimed in claim 1 comprising in addition an outer layer of insulation engaging the outer face of said first envelope.
3. A cold pack as claimed in claim 2 in which said layer of insulation comprises a layer of flexible foam plastic material secured adjacent the face of said first envelope, and in which a closure member is secured to said insulation layer for releasably maintaining said cold pack in folded position with said insulation layer outermost.
4. A cold pack as claimed in claim 3 in which said insulation layer includes a continuous film of flexible plastic bonded to said foam plastic material at the face adjacent said first envelope, and said first envelope is heat sealed along at least one marginal portion thereof to said insulation layer.
5. A cold pack as claimed in claim 4 in which said insulation layer extends fully across the adjacent first envelope and extends substantially beyond at least one margin of said first envelope to provide a flap, and said closure member is secured to the margin of said flap remote from said first envelope.
6. A cold pack as claimed in claim 5 in which said inner envelope is formed of a single layer of polyethylene film and said outer envelope is formed of a double layer of said film, is of rectangular configuration, and is heat sealed along three margins to said insulation layer.
7. A cold pack as claimed in claim 5 in which said closure member has a pressure-sensitive adhesive face for releasably holding the margin of said flap against the outer face of said insulation layer.
8. A cold pack as claimed in claim 1, in which said temperature regulation means functions to cool said sample to a temperature of 28°-40°F for a period of at least 45 minutes.
9. A disposable cold pack for cooling and storing a container filled with a sample of freshly drawn blood comprising A. a temperature regulation means which comprises the elements of a single sealed flexible outer envelope of plastic material, B. an outer insulating layer of flexible foam plastic material engaging the outer face of said outer envelope and secured thereto, said insulating layer extending fully across the face of said first envelope and substantially beyond at least one margin of said envelope to form a flexible flap, C. a supply of dry solid ammonium nitrate disposed within said outer envelope, D. an inner sealed and frangible envelope con-taining a supply of water disposed within said outer envelope and arranged to be broken by pressure applied externally to said outer envelope to release said supply of water into said supply of ammonium nitrate within said outer sealed envelope to activate said cold pack, the weight ratio of ammonium nitrate to water being from 1.24:1 to 1.26:1 and the total weight of ammonium nitrate and water being from 180 to 200 grams, a closure member secured to said insulation layer flap at the margin thereof remote from said outer envelope for releasably maintaining said cold pack in folded position with said insulation layer outermost extending completely around the outer circumference of said folded cold pack, said cold pack being adapted to be folded around said sample container with the container in contact with said outer envelope for the elements of said temperature regulation means cooperatively functioning to chill said blood sample rapidly and to maintain it at a temperature of 28° to 40°F. for at least 45 minutes after activation in room temperature surroundings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US55672175A | 1975-03-10 | 1975-03-10 | |
| US556,721 | 1975-03-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1083090A true CA1083090A (en) | 1980-08-05 |
Family
ID=24222567
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA247,167A Expired CA1083090A (en) | 1975-03-10 | 1976-03-03 | Disposable cold pack for blood specimen |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1083090A (en) |
-
1976
- 1976-03-03 CA CA247,167A patent/CA1083090A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |