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Tissue reaction to jet injection
Tissue reaction to jet injection A. K. ElGeneidy, Bostoq Mass. CLINICAL
RESEARCH
A. A. Bloom, J. H. Skerman, CENTER,
BOSTON
UNIVERSITY
a#nndR. E. Stallard, SCHOOL
OF
GRADUATE
DENTISTRY
An animal study of injections delivered by the jet technique reveals that injected solutions follow lines of least resistance in the fascial planes; both jet and needle injection techniques produce similar inflammatory responses in the underlying tissues, the severity of which depends on the amount of trauma or damage to those tissues ; inflammatory reaction is more localized with needle injections than that ohserved with jet injections; adventitia of blood vessels, perineurium, and periosteum apparently form a harrier that the jet stream cannot easily penetrate after it has lost its velocity following penetration of the tissues; and the amount of loose areolar connective tissue present subcutaneously at the injection site determines the volume which may be accommodated by the tissues.
A
new approach to parenteral injections introduced by Figge and Schererl in 1947 aroused broad interest in the fields of medicine and surgery. This represented the first fundamental change in the basic principles of injection since Alexander Wood introduced the hypodermic injection in 1853.2 The method is based upon the fact that liquid substances forced through very small openings or jets at very high pressure can penetrate the skin or mucosa. The technique is described as the “jet injection,” whereby one can administer substances hypodermically without the use of needles or syringes. Since its introduction to medical practice”! 4 and later to dental practice,s numerous studies have been carried out to evaluate its clinical eflcctiveness-‘~ (i-1;{while others have demonstrated its tissue-penetration characteristics.3, 14-li The present investigation was conducted to study tissue reaction and tissue damage, if any, at timed intervals following an injection administered by the
AND
MATERIALS
The instruments used in this study were a Syrijet Mark II (Fig. 1) and a sterile disposable tuberculin syringe with a 26 gauge needle. The investigation was carried out on thirty rats, divided into four groups. The number of animals in each group, the materials injected, and the times of death appear in Table I. 501
502
ElGeneidy
et al.
Oral Surg. October, 1974
The injection sites used were the thighs, the shoulders, and the head over the parietal bones. The right side was used as the experimental side, where a jet injection was given, and the left side served as a control, where a needle syringe injection of similar quantity and solution was given. The areas of injection were first shaved and then cleaned with soap and water and swabbed with 70 per cent ethyl alcohol. An area was marked on the skin of the thighs, shoulders, and head, and the injections were given in the center of these areas. Group
1
All rats in this group were first anesthetized with ether and then given saline injections, 0.2 ml. in the thighs and shoulders and 0.05 ml. in the head over the parietal bones. At the timed intervals, the’ rats were killed and perfused with neutral buffered formalin solution according to a technique described by Pease.ls The specimens were recovered, fixed in neutral buffered formalin, and processed for routine histologic study. Group
2
The solution injected and the volumes were similar to those of Group 1. Two hours before the scheduled time of death, the animals received three intraperitoneal injections of 1.0 ml. of 2 per cent trypan blue at half-hour intervals. Half an hour after the last injection, the animals were killed and specimens were processed as previously described, with the use of Lavodowsky’s solution. Serial sections were cut at 15 microns, and every fifth section a 6-micron section was obtained. The 15-micron sections were examined without counterstaining and the 6-micron sections were stained with hematoxylin and eosin. Group
3
In this group, the two rats were injected with 0.2 ml. of a 1 per cent solution of trypan blue in the thighs and shoulders and with 0.05 ml. in the head. The animals were killed immediately, and the histologic procedures were similar to those described for Group 2. Group
4
India ink injections were given, and the animals were killed immediately with an overdose of ether. Specimens were recovered, fixed in neutral buffered
Volume 38 Number 4
Tissue reaction
to jet injectim
503
Fig. 8. Photomicrographs demonstrating epithelial cells displaced into the connective tissue immediately following needle (A) and jet (23) injections of saline solution. Note the disruption of the connective tissue fibers in the areas where the solution was deposited. Magnification, x50.)
formalin, and later decalcified in a 20 per cent solution of formic acid. All specimens were cut into sections 1 mm, thick parallel to the skin surface. The specimens were washed, dehydrated, and cleared for stereoscopic examination according to a technique described by Clynes. I9 Following stereoscopic examination, the specimens were embedded in paraffin, and serial sections were cut and stained with hematoxylin and eosin. RESULTS
The results of the histologic examinations of the serial sections will be presented for the groups of animals from which the specimens were obtained.
Oral Rurg. October, 1974 Table
I. IXstribut,ion NO.
o F animals Material injected
Growp
of rats
1 2
18 7
Saline Saline
3 4 Total
1 2 2 30
1-s trypan India ink
Group
Time of death
Bemarks
0, 1, 2, 3, 4, 6, 12, 24, and 48 hrs. iujections 1ntr:tperitonenl 2, 3, 4, 6, 12, 24, and 48 1~s. of 1 ml. of 2% trypxn blue As ahove 2 brs. blue Immediately Tmmediately
1
Examination of serial sections from areas injected with the Syrijet demonstrated that the jet spray penetrated the epidermis as a tine column of fluid, tearing the surface epithelium and pushing it inward toward the connective tissue. After penetrating the epidermis, it began to spread laterally and deeply in the underlying tissue, causing its disruption. Torn epithelial cells were seen in the connective tissue, and it appeared that these epithelial cells were forced in by the jet spray (Fig. 2, B). The path of the conventional needle was clear cut and wider in diameter than that of the Syrijet. The connective tissue and muscle fibers were disrupted from the deposited solution. Epithelial cells were also seen deposited in the underlying connective tissue (Fig. 2, -4). Apparently, during penetration, the tip of the needle had torn epithelial cells which were carried into deeper tissues and forced into the connective tissue during the injection. Areas of hemorrhage and signs of acute inflammation were observed with dilation and engorgement of the blood vessels, migration of leukocytes, and acute inflammatory cell infiltration (Fig. 3). The cells present were primarily polymorphonuclear leukocytes. With time, there was an increase in the amount of inflammatory cell infiltration in the tissues. The severe disruption of the connective tissue fibers seen in the early stages due to the injected solution was less marked as time passed, and by the end of 4 hours there was only very slight disruption, probably due to the inflammatory exudate, the injected solution being completely resorbed with time. Both the needle and jet injections showed similar histologic changes, with the exception that reactions with the needle injections were not as diffuse as those seen with the jet. All specimens showed signs of acute inflammation in the 0-, I-, 2-, 3-, 4-, and 6-hour sections. Some specimens demonstrated signs of resolution, with a decreased number of leukocytes in the a,rea and an increase in the number of macrophages at 12 hours. Complete resolution was observed in most of the 4%hour specimens. Group
2
In this group the vital dye was taken up by some connective tissue and muscle fibers. With jet injections, the most superficial connective tissue fibers and the superficial layers of the muscle fibers stained with the trypan blue. These areas
Volume 38 Number 4
Tissue reactio?z to jet injection
505
Fig. 8. Six-hour photomicrographs following needle (A) and jet (B) injections of saline solution demonstrating acute idammation and hemorrhage into the connective tissue. Note the similarity between the two reactions. (Magnification, x50.)
were shown to be related to the path of the main jet stream. With the needle injection, the areaa stained by the trypan blue could be traced to the path of the needle or the disrupted connective tissue and muscle fibers and their immediate vicinity. The intensity of the blue stain was reduced with time. The difference was very obvious between the 1%, 24-, and 48-hour specimens. The only difference seen between the jet injection and the needle injection was in the area of the blue staining. Jet injections showed a wider area of stain than needle injections, but no differences in the extent of vital dye staining could be observed between the different sites of injections. Group
3
The injection of 1 per cent trypan blue directly into the tissues demonstrated the extent and the method of spread of the injected material. The trypan blue dye injected with the jet was spread over a wide area after penetrating the skin,
SO6 ElGeneidy
Oral Surg. October, 1974
et al.
Fig. 4. Photomicrograph of a histologic section onstrating the intense staining of both connective x100.)
after jet injection tissue and muscle
of trypan blue demfibers. Magnification,
staining the subcutaneous connective tissue, the connective tissue between the muscle bundles, and the most superficial layers of the muscle fibers (Fig. 4). The solution injected subcutaneously with the needle appears to be localized in one area, and again a small amount followed the lines of least resistance. This was shown by an intense trypan blue staining of the connective tissue, with no staining of the muscle fibers. Intramuscular injections, however, showed intense vital dye staining of both connective tissue and disrupted muscle fibers (Fig. 5). Group
4
Cleared specimens of India ink injections made with the Syrijet showed an irregular and feathery outline in the lateral borders of subcutaneous tissue and within the muscles. In contrast, the needle injections demonstrated a regular outline, with coarse projections in the subcutaneous tissue and a feathery outline in the muscle. In both cases the fluid followed the lines of least resistance. The needle-injected solution was more localized, with minimal spread of solution into the tissues, while jet injections produced a more diffuse spread. The spread of solution in the muscle was similar in both types of injection, as seen in cleared and histologic sections (Fig. 6). The solution spreads along the connective tissue fibers between the muscle bundles and the individual muscles fibers. No India ink particles were seen penetrating blood vessels or nerves in any of the specimens examined; however, India ink particles were seen in the connective tissues surrounding blood vessels and nerves (Fig. 7). DISCUSSION
The initial reaction of the tissues to both methods of injection substantiates those described by Bell and associates,17 Bennett, Mundell, and Monheim,l” and Ikehara and colleagues.Zo The reaction consisted of tearing of the underlying
Volume 38 Number 4
Tissue reactio?l to jet injection
507
Fdg. 5. Photomicrographs of histologic sections taken after subcutaneous (A) and intramuscular (B) needle injections of trypan blue, demonstrating the intense staining of the connective tissue fibers in the first and muscle fibers in the second. (Magnification, x100.)
connective tissue and dilation and engorgement of the blood vessels in the region. It was impossible to discern whether the disruption of the tissues was due to the inflammatory fluid exudates, the solutions injected, or a combination of both. Comparisons between tissue responses produced by needle and jet injections showed the inflammatory reaction in the former to be more localized than in the latter. The cause of the inflammatory reaction with the jet technique could be attributed to the disruption of the tissues from the force of penetration of the injected fluid. With needle injection, however, the cause may be a tissue disruption when the injection is administered rapidly, the passage of the needle itself, or a combination of both. It was also shown in this study that, with both injection techniques, epithelial tissue may be forced into the underlying connective tissue. Gibson and NorrisZ1 and Cawson 22have demonstrated that displacement of epithelial cells in the con-
508
ElGeneidy
et al.
Oral Surg. October, 1974
Fig. 6. Photomicrographs of tissue sections following intramuscular needle injections of India ink (A) and jet injection (23). No differences could be observed in the spread of solution within the muscles. (Magnification, x100.)
nective tissue could occur with needle injections. The fate of the displaced epithelial tissues has not been adequately investigated. Thompson2” has shown that buried epithelial elements following skin grafts first form microcysts, which later degenerate. Resolution and healing with both injection techniques usually occur within 24 to 48 hours. As there was no marked difference in the tissue reaction in different sites of injection, one can conclude that the amount of trauma produced by a particular technique is that which elicits the difference in response. It must be emphasized that the inflammation seen was always confined to the soft-tissue areas and there was no evidence at any time of inflammation or hemorrhage, either underneath the periosteum or within the bone.
Tissue reactiovb to jet injection
509
Fig. 7. Photomicrograph of a histologic section after jet injection of India ink, demonstrating India ink particles surrounding blood vessels and a nerve. (Magnification, x100.)
It has-been demonstrated by Figge and Barnett,” Hughes and associates,G that inadvertent intraStephens and Kramer,14 and Bennett and co-worker9 venous injection is theoretically possible, and yet it did not occur in this investigation. India ink particles were never seen in the lumina of blood vessels but, rather, in the connective tissues surrounding these structures. This is possibly due to the sliding away of the vessels from the main stream of the jet or to the strong barrier presented by the conective tissue of the adventitia of blood vessels and the perineurium of nerves, which the jet stream cannot easily perforate after it has lost its velocity following tissue penetration. The observations made from rat specimens injected with India ink were similar to those reported by Stephens and KrameP and Whitehead and Young15 in their autopsy material. *Jet injectons of India ink spread laterally immediately following penetration of the surface epithelium; yet the main stream was still penetrating deeper into the tissues. Lateral spread was more obvious in the loose areolar connective tissue and between the muscle bundles, indicating that injected material invariably follows the path of least resistance. The inflammatory response observed in animals injected with saline solution followed the same pattern. It was also apparent that the subcutaneous tissues could accommodate a ecrtain quantity of fluid when injected with the Syrijet. If this volume is increased, the tissues will not accept the excess quantity rapidly enough, so it will bounce away from the surface without penetrating the tissues. The quantity of injected material which any tissue can accommodate depends largely on the site of injection and how adherent the underlying tissue is. A good example was observed in injections administered over the parietal bones. When any quantity in excess of 0.05 ml. was injected, some of the solution would not penetrate the tissues and rebounded from the surface.
510
ElGeneidy
et al.
Oral Surg. October, 1974
The technique of vital dye staining has been utilized by Williams and Frantz,21 Williams,25 and Stallard and SchaffePF to trace injury and repair. They concluded that when vital dyes become bound to damaged tissues and cells, they are not dissolved by the various solvents used during preparation of histologic sections. Examination of unstained histologic sections obtained from animals that received intraperitoneal injections of 2 per cent trypan blue showed that some connective tissue and muscle fibers retained the blue coloration. The intensity of the vital dye stain becomes less obvious with the passage of time. In another instance where trypan blue was injected directly into the tissue, some of the superficial muscle fibers and connective tissue fibers were intensely stained with the dye. Intramuscular trypan blue injections with the needle showed intense staining of those fibers directly related to where the needle passed and the solution was deposited. The distribution of the heavily stained fibers conforms roughly with those tissues that retained the trypan blue injections discussed previously. These observations demonstrate that some damage to muscle fibers and connective tissue fibers does occur within the line of penetration of both needle and jet injection. SUMMARY
AND
CONCLUSIONS
An animal investigation was conducted to study injections delivered by the jet technique. Tissue reaction and penetration characteristics of jet and needle injections were investigated in thirty adult rats divided into four groups. Group 1 animals were injected with saline solution and killed, two at a time immediately and at intervals of 1, 2, 3, 4, 6, 12, 24, and 48 hours. Group 2 animals were injected with saline solution and killed, one at a time at intervals of 2, 3, 4, 6, 12, 24, and 48 hours. This group received an intraperitoneal injection of 1 ml. of 2 per cent trypan blue at half-hour intervals for a total of three injections, and the animals were killed a half-hour after the last injection. One rat did not receive a saline injection and was useaas a control. Group 3 animals were injected with 1 per cent trypan blue and killed immediately. Group 4 animals were injected with India ink and killed immediately. From the data presented in this investigation, the following conclusions can be drawn : 1. Injected solutions follow lines of least resistance in the fascial planes. 2. Both injection techniques produce similar inflammatory responses in the underlying tissues, the severity of which depends on the amount of trauma or damage to those tissues. 3. Inflammatory reaction is more localized with needle injections than that observed with jet injections. 4. Aclventitia of blood vessels, perineurium, and periosteum apparently form a barrier that the jet stream cannot easily penetrate after it has lost its velocity following penetration of the tissues. 5. The amount of loose areolar connective tissue present subcutaneously at the injection site determines the volume which may be accommodated by the tissues.
Volume Number
Tissue reactim
38 4
to jet injection
511
RERRENCES
Studies on Jet Penetration of Human 1. Figge, F. H. J., and Scherer, R. P.: Anatomical Skin for Subcutaneous Medication Without the Use of Needles (Abstr.), Anat. Rec. 97: 335, 1947. 2. Howard-Jones. N.: The Orinins of Hvnodermic Medication. Sci. Am. 224: 96-102. 1971. 3. Figge, F. H. J., and Barn&, D. M.“zIAnatomic Evaluation of a Jet Injection ‘Instrument designed to Minimize Pain and Inconvenience of Parenteral Therapy, 3: _. Am. Pratt. 197;19448. 4. Hingson, R. A., and Hughes, J. G.: Clinical Studies With Jet Injection: A New Method of Drug Administration, Anesth. Analg. 26: 221, 1947. 5. Margetis, P. M., Quarantillo, E. P., and Lindbeorg, R. B.: Jet Injection Local Anesthesia in Dentistry: A Report of 66 Cases, U.S. Armed Forces Med. J. 9: 625, 1958. in Pediatric Practice, 6. Hughes, J. G., Jordan, R. G., and Hill, F. 8.: Jet Injection Pediatrics 3: 801. 1949. 7. Warren, J., Ziherl, F. A., Kish, A. W., and Ziherl, L. A.: Large Scale Administration of Vaccines bv Means of an Automatic Jet Iniection Syringe. J. A. M. A. 157: 633. 1955. 8. Ku&her, h. M., and Zegarelli, E. V.: An Intra:oralJet Injection Technique: Clinical Impression, N. Y. J. Dent. 35: 219, 1965. 9. Epstein, 5. : Pressure Injection of Local Anesthetics: Clinical Evaluation of an instrument, J. Am. Dent. Assoc. 82: 374, 1971. 10. Arefian, D., Henry, J. L., and Whitehurst, V.: Clinical Evaluation of a Syringe-Loaded Gun, ORAL SURG.~~: 168,1972. 11. Schmidt, D. A.: Anesthesia by Jet Injection in the Practice of Pedodontics, J. Dent. Child. 33: 340, 1966. 12. Bennett, C. R., and Monheim, L. M.: Production of Local Anesthesia by Jet Injection,
ORAL SURG.32: 526,1971. 13. Garellek, A. L.: Clinical Evaluation of a Jet Injector for Local Anesthesia, J. Can. Dent. Assoc. 33: 329, 1967. 14. Stephens, R. R., and Kramer, I. R. H.: Intra-oral Injection by High Pressure Jet, Br. Dent. J. 117: 465, 1964. 15. Whitehead, F. I. H., and Young, I.: An Intra-oral Jet Injection Instrument: An Histological, Bacteriological and Clinical Assessment, Br. Dent. J. 125: 437, 1968. 16. Bennett, C. R., Mundell, R. D., and Monheim, L. M.: Studies on Tissue Penetration Characteristics Produced by Jet Injection, J. Am. Dent. Assoc. 83: 625, 1971. 17. Bell, W. A., Kimble, A, Traeger, K. A., and Hanson, L. S.: Histologic Evaluation of a Jet Injection of 2 Per Cent Lidocaine Solution on the Oral Mucosa of a Mixed-Breed Dog. A Review and Experimental Study, ORAL STJRG.31: 79, 1971. 18. Pease, D. C.: Histological Techniques for Electron Microscopy, ed. 2, New York, 1964, Academic Press. Inc.. D. 23. 19. Clynes, J. T.: The Path of Inflammation Into the Supporting Structures, Thesis, Boston University School of Graduate Dentistry, 1972. 20. Ikehara, N. K., McKibben, D. H., Pechersky, J. L., and Rapp, R,.: Comparison of Jet Injection and Needle-Syringe Injection Techniques in Production of Edema, J. Dent. Res. 51: 573, 1972. 21. ~~$c~$~~., and Norris, W.: Skin Fragments Removed by Injection Needles, Lancet 2: 22. Ca&um, R. A.: The Implantation of Cells From the Oral Mucous Membrane by Injection Needles, Arch. Oral Biol. 1: 206, 1959. 23. Thompson, N.: A Clinical and Histological Investigation Into the Fate of Epithelial Elements Buried Following the Grafting of “Shaved’, Skin Surfaces-Based on a Study of the Healing of Split-Skin Graft Donor Sites in Man, Br. J. Plast. Surg. 13: 219, 1960. 24. Williams, W. L., and Frantz, M.: Histologic Techniques in the Study of Vitally Stained Normal and Damaged Cells, Anat. Rec. 100: 547, 1948. 25. Williams, W. L.: Studies of Vitally Stained Normal and Damaged Cells (Abstr.), Anat. Rec. 100: 723, 1948. 26. Stallard, R. E., and Schaffer, E. M.: Vital Staining of the Periodontium of White Mice, J. Periodontol. 8.3: 183, 1962. Reprint requests to : Dr. A. K. ElGeneidy Clinical Research Center Boston University School of Graduate 100 East Newton St. Boston, Mass. 02118
Dentistry
RESEARCH
A. A. Bloom, J. H. Skerman, CENTER,
BOSTON
UNIVERSITY
a#nndR. E. Stallard, SCHOOL
OF
GRADUATE
DENTISTRY
An animal study of injections delivered by the jet technique reveals that injected solutions follow lines of least resistance in the fascial planes; both jet and needle injection techniques produce similar inflammatory responses in the underlying tissues, the severity of which depends on the amount of trauma or damage to those tissues ; inflammatory reaction is more localized with needle injections than that ohserved with jet injections; adventitia of blood vessels, perineurium, and periosteum apparently form a harrier that the jet stream cannot easily penetrate after it has lost its velocity following penetration of the tissues; and the amount of loose areolar connective tissue present subcutaneously at the injection site determines the volume which may be accommodated by the tissues.
A
new approach to parenteral injections introduced by Figge and Schererl in 1947 aroused broad interest in the fields of medicine and surgery. This represented the first fundamental change in the basic principles of injection since Alexander Wood introduced the hypodermic injection in 1853.2 The method is based upon the fact that liquid substances forced through very small openings or jets at very high pressure can penetrate the skin or mucosa. The technique is described as the “jet injection,” whereby one can administer substances hypodermically without the use of needles or syringes. Since its introduction to medical practice”! 4 and later to dental practice,s numerous studies have been carried out to evaluate its clinical eflcctiveness-‘~ (i-1;{while others have demonstrated its tissue-penetration characteristics.3, 14-li The present investigation was conducted to study tissue reaction and tissue damage, if any, at timed intervals following an injection administered by the
AND
MATERIALS
The instruments used in this study were a Syrijet Mark II (Fig. 1) and a sterile disposable tuberculin syringe with a 26 gauge needle. The investigation was carried out on thirty rats, divided into four groups. The number of animals in each group, the materials injected, and the times of death appear in Table I. 501
502
ElGeneidy
et al.
Oral Surg. October, 1974
The injection sites used were the thighs, the shoulders, and the head over the parietal bones. The right side was used as the experimental side, where a jet injection was given, and the left side served as a control, where a needle syringe injection of similar quantity and solution was given. The areas of injection were first shaved and then cleaned with soap and water and swabbed with 70 per cent ethyl alcohol. An area was marked on the skin of the thighs, shoulders, and head, and the injections were given in the center of these areas. Group
1
All rats in this group were first anesthetized with ether and then given saline injections, 0.2 ml. in the thighs and shoulders and 0.05 ml. in the head over the parietal bones. At the timed intervals, the’ rats were killed and perfused with neutral buffered formalin solution according to a technique described by Pease.ls The specimens were recovered, fixed in neutral buffered formalin, and processed for routine histologic study. Group
2
The solution injected and the volumes were similar to those of Group 1. Two hours before the scheduled time of death, the animals received three intraperitoneal injections of 1.0 ml. of 2 per cent trypan blue at half-hour intervals. Half an hour after the last injection, the animals were killed and specimens were processed as previously described, with the use of Lavodowsky’s solution. Serial sections were cut at 15 microns, and every fifth section a 6-micron section was obtained. The 15-micron sections were examined without counterstaining and the 6-micron sections were stained with hematoxylin and eosin. Group
3
In this group, the two rats were injected with 0.2 ml. of a 1 per cent solution of trypan blue in the thighs and shoulders and with 0.05 ml. in the head. The animals were killed immediately, and the histologic procedures were similar to those described for Group 2. Group
4
India ink injections were given, and the animals were killed immediately with an overdose of ether. Specimens were recovered, fixed in neutral buffered
Volume 38 Number 4
Tissue reaction
to jet injectim
503
Fig. 8. Photomicrographs demonstrating epithelial cells displaced into the connective tissue immediately following needle (A) and jet (23) injections of saline solution. Note the disruption of the connective tissue fibers in the areas where the solution was deposited. Magnification, x50.)
formalin, and later decalcified in a 20 per cent solution of formic acid. All specimens were cut into sections 1 mm, thick parallel to the skin surface. The specimens were washed, dehydrated, and cleared for stereoscopic examination according to a technique described by Clynes. I9 Following stereoscopic examination, the specimens were embedded in paraffin, and serial sections were cut and stained with hematoxylin and eosin. RESULTS
The results of the histologic examinations of the serial sections will be presented for the groups of animals from which the specimens were obtained.
Oral Rurg. October, 1974 Table
I. IXstribut,ion NO.
o F animals Material injected
Growp
of rats
1 2
18 7
Saline Saline
3 4 Total
1 2 2 30
1-s trypan India ink
Group
Time of death
Bemarks
0, 1, 2, 3, 4, 6, 12, 24, and 48 hrs. iujections 1ntr:tperitonenl 2, 3, 4, 6, 12, 24, and 48 1~s. of 1 ml. of 2% trypxn blue As ahove 2 brs. blue Immediately Tmmediately
1
Examination of serial sections from areas injected with the Syrijet demonstrated that the jet spray penetrated the epidermis as a tine column of fluid, tearing the surface epithelium and pushing it inward toward the connective tissue. After penetrating the epidermis, it began to spread laterally and deeply in the underlying tissue, causing its disruption. Torn epithelial cells were seen in the connective tissue, and it appeared that these epithelial cells were forced in by the jet spray (Fig. 2, B). The path of the conventional needle was clear cut and wider in diameter than that of the Syrijet. The connective tissue and muscle fibers were disrupted from the deposited solution. Epithelial cells were also seen deposited in the underlying connective tissue (Fig. 2, -4). Apparently, during penetration, the tip of the needle had torn epithelial cells which were carried into deeper tissues and forced into the connective tissue during the injection. Areas of hemorrhage and signs of acute inflammation were observed with dilation and engorgement of the blood vessels, migration of leukocytes, and acute inflammatory cell infiltration (Fig. 3). The cells present were primarily polymorphonuclear leukocytes. With time, there was an increase in the amount of inflammatory cell infiltration in the tissues. The severe disruption of the connective tissue fibers seen in the early stages due to the injected solution was less marked as time passed, and by the end of 4 hours there was only very slight disruption, probably due to the inflammatory exudate, the injected solution being completely resorbed with time. Both the needle and jet injections showed similar histologic changes, with the exception that reactions with the needle injections were not as diffuse as those seen with the jet. All specimens showed signs of acute inflammation in the 0-, I-, 2-, 3-, 4-, and 6-hour sections. Some specimens demonstrated signs of resolution, with a decreased number of leukocytes in the a,rea and an increase in the number of macrophages at 12 hours. Complete resolution was observed in most of the 4%hour specimens. Group
2
In this group the vital dye was taken up by some connective tissue and muscle fibers. With jet injections, the most superficial connective tissue fibers and the superficial layers of the muscle fibers stained with the trypan blue. These areas
Volume 38 Number 4
Tissue reactio?z to jet injection
505
Fig. 8. Six-hour photomicrographs following needle (A) and jet (B) injections of saline solution demonstrating acute idammation and hemorrhage into the connective tissue. Note the similarity between the two reactions. (Magnification, x50.)
were shown to be related to the path of the main jet stream. With the needle injection, the areaa stained by the trypan blue could be traced to the path of the needle or the disrupted connective tissue and muscle fibers and their immediate vicinity. The intensity of the blue stain was reduced with time. The difference was very obvious between the 1%, 24-, and 48-hour specimens. The only difference seen between the jet injection and the needle injection was in the area of the blue staining. Jet injections showed a wider area of stain than needle injections, but no differences in the extent of vital dye staining could be observed between the different sites of injections. Group
3
The injection of 1 per cent trypan blue directly into the tissues demonstrated the extent and the method of spread of the injected material. The trypan blue dye injected with the jet was spread over a wide area after penetrating the skin,
SO6 ElGeneidy
Oral Surg. October, 1974
et al.
Fig. 4. Photomicrograph of a histologic section onstrating the intense staining of both connective x100.)
after jet injection tissue and muscle
of trypan blue demfibers. Magnification,
staining the subcutaneous connective tissue, the connective tissue between the muscle bundles, and the most superficial layers of the muscle fibers (Fig. 4). The solution injected subcutaneously with the needle appears to be localized in one area, and again a small amount followed the lines of least resistance. This was shown by an intense trypan blue staining of the connective tissue, with no staining of the muscle fibers. Intramuscular injections, however, showed intense vital dye staining of both connective tissue and disrupted muscle fibers (Fig. 5). Group
4
Cleared specimens of India ink injections made with the Syrijet showed an irregular and feathery outline in the lateral borders of subcutaneous tissue and within the muscles. In contrast, the needle injections demonstrated a regular outline, with coarse projections in the subcutaneous tissue and a feathery outline in the muscle. In both cases the fluid followed the lines of least resistance. The needle-injected solution was more localized, with minimal spread of solution into the tissues, while jet injections produced a more diffuse spread. The spread of solution in the muscle was similar in both types of injection, as seen in cleared and histologic sections (Fig. 6). The solution spreads along the connective tissue fibers between the muscle bundles and the individual muscles fibers. No India ink particles were seen penetrating blood vessels or nerves in any of the specimens examined; however, India ink particles were seen in the connective tissues surrounding blood vessels and nerves (Fig. 7). DISCUSSION
The initial reaction of the tissues to both methods of injection substantiates those described by Bell and associates,17 Bennett, Mundell, and Monheim,l” and Ikehara and colleagues.Zo The reaction consisted of tearing of the underlying
Volume 38 Number 4
Tissue reactio?l to jet injection
507
Fdg. 5. Photomicrographs of histologic sections taken after subcutaneous (A) and intramuscular (B) needle injections of trypan blue, demonstrating the intense staining of the connective tissue fibers in the first and muscle fibers in the second. (Magnification, x100.)
connective tissue and dilation and engorgement of the blood vessels in the region. It was impossible to discern whether the disruption of the tissues was due to the inflammatory fluid exudates, the solutions injected, or a combination of both. Comparisons between tissue responses produced by needle and jet injections showed the inflammatory reaction in the former to be more localized than in the latter. The cause of the inflammatory reaction with the jet technique could be attributed to the disruption of the tissues from the force of penetration of the injected fluid. With needle injection, however, the cause may be a tissue disruption when the injection is administered rapidly, the passage of the needle itself, or a combination of both. It was also shown in this study that, with both injection techniques, epithelial tissue may be forced into the underlying connective tissue. Gibson and NorrisZ1 and Cawson 22have demonstrated that displacement of epithelial cells in the con-
508
ElGeneidy
et al.
Oral Surg. October, 1974
Fig. 6. Photomicrographs of tissue sections following intramuscular needle injections of India ink (A) and jet injection (23). No differences could be observed in the spread of solution within the muscles. (Magnification, x100.)
nective tissue could occur with needle injections. The fate of the displaced epithelial tissues has not been adequately investigated. Thompson2” has shown that buried epithelial elements following skin grafts first form microcysts, which later degenerate. Resolution and healing with both injection techniques usually occur within 24 to 48 hours. As there was no marked difference in the tissue reaction in different sites of injection, one can conclude that the amount of trauma produced by a particular technique is that which elicits the difference in response. It must be emphasized that the inflammation seen was always confined to the soft-tissue areas and there was no evidence at any time of inflammation or hemorrhage, either underneath the periosteum or within the bone.
Tissue reactiovb to jet injection
509
Fig. 7. Photomicrograph of a histologic section after jet injection of India ink, demonstrating India ink particles surrounding blood vessels and a nerve. (Magnification, x100.)
It has-been demonstrated by Figge and Barnett,” Hughes and associates,G that inadvertent intraStephens and Kramer,14 and Bennett and co-worker9 venous injection is theoretically possible, and yet it did not occur in this investigation. India ink particles were never seen in the lumina of blood vessels but, rather, in the connective tissues surrounding these structures. This is possibly due to the sliding away of the vessels from the main stream of the jet or to the strong barrier presented by the conective tissue of the adventitia of blood vessels and the perineurium of nerves, which the jet stream cannot easily perforate after it has lost its velocity following tissue penetration. The observations made from rat specimens injected with India ink were similar to those reported by Stephens and KrameP and Whitehead and Young15 in their autopsy material. *Jet injectons of India ink spread laterally immediately following penetration of the surface epithelium; yet the main stream was still penetrating deeper into the tissues. Lateral spread was more obvious in the loose areolar connective tissue and between the muscle bundles, indicating that injected material invariably follows the path of least resistance. The inflammatory response observed in animals injected with saline solution followed the same pattern. It was also apparent that the subcutaneous tissues could accommodate a ecrtain quantity of fluid when injected with the Syrijet. If this volume is increased, the tissues will not accept the excess quantity rapidly enough, so it will bounce away from the surface without penetrating the tissues. The quantity of injected material which any tissue can accommodate depends largely on the site of injection and how adherent the underlying tissue is. A good example was observed in injections administered over the parietal bones. When any quantity in excess of 0.05 ml. was injected, some of the solution would not penetrate the tissues and rebounded from the surface.
510
ElGeneidy
et al.
Oral Surg. October, 1974
The technique of vital dye staining has been utilized by Williams and Frantz,21 Williams,25 and Stallard and SchaffePF to trace injury and repair. They concluded that when vital dyes become bound to damaged tissues and cells, they are not dissolved by the various solvents used during preparation of histologic sections. Examination of unstained histologic sections obtained from animals that received intraperitoneal injections of 2 per cent trypan blue showed that some connective tissue and muscle fibers retained the blue coloration. The intensity of the vital dye stain becomes less obvious with the passage of time. In another instance where trypan blue was injected directly into the tissue, some of the superficial muscle fibers and connective tissue fibers were intensely stained with the dye. Intramuscular trypan blue injections with the needle showed intense staining of those fibers directly related to where the needle passed and the solution was deposited. The distribution of the heavily stained fibers conforms roughly with those tissues that retained the trypan blue injections discussed previously. These observations demonstrate that some damage to muscle fibers and connective tissue fibers does occur within the line of penetration of both needle and jet injection. SUMMARY
AND
CONCLUSIONS
An animal investigation was conducted to study injections delivered by the jet technique. Tissue reaction and penetration characteristics of jet and needle injections were investigated in thirty adult rats divided into four groups. Group 1 animals were injected with saline solution and killed, two at a time immediately and at intervals of 1, 2, 3, 4, 6, 12, 24, and 48 hours. Group 2 animals were injected with saline solution and killed, one at a time at intervals of 2, 3, 4, 6, 12, 24, and 48 hours. This group received an intraperitoneal injection of 1 ml. of 2 per cent trypan blue at half-hour intervals for a total of three injections, and the animals were killed a half-hour after the last injection. One rat did not receive a saline injection and was useaas a control. Group 3 animals were injected with 1 per cent trypan blue and killed immediately. Group 4 animals were injected with India ink and killed immediately. From the data presented in this investigation, the following conclusions can be drawn : 1. Injected solutions follow lines of least resistance in the fascial planes. 2. Both injection techniques produce similar inflammatory responses in the underlying tissues, the severity of which depends on the amount of trauma or damage to those tissues. 3. Inflammatory reaction is more localized with needle injections than that observed with jet injections. 4. Aclventitia of blood vessels, perineurium, and periosteum apparently form a barrier that the jet stream cannot easily penetrate after it has lost its velocity following penetration of the tissues. 5. The amount of loose areolar connective tissue present subcutaneously at the injection site determines the volume which may be accommodated by the tissues.
Volume Number
Tissue reactim
38 4
to jet injection
511
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Studies on Jet Penetration of Human 1. Figge, F. H. J., and Scherer, R. P.: Anatomical Skin for Subcutaneous Medication Without the Use of Needles (Abstr.), Anat. Rec. 97: 335, 1947. 2. Howard-Jones. N.: The Orinins of Hvnodermic Medication. Sci. Am. 224: 96-102. 1971. 3. Figge, F. H. J., and Barn&, D. M.“zIAnatomic Evaluation of a Jet Injection ‘Instrument designed to Minimize Pain and Inconvenience of Parenteral Therapy, 3: _. Am. Pratt. 197;19448. 4. Hingson, R. A., and Hughes, J. G.: Clinical Studies With Jet Injection: A New Method of Drug Administration, Anesth. Analg. 26: 221, 1947. 5. Margetis, P. M., Quarantillo, E. P., and Lindbeorg, R. B.: Jet Injection Local Anesthesia in Dentistry: A Report of 66 Cases, U.S. Armed Forces Med. J. 9: 625, 1958. in Pediatric Practice, 6. Hughes, J. G., Jordan, R. G., and Hill, F. 8.: Jet Injection Pediatrics 3: 801. 1949. 7. Warren, J., Ziherl, F. A., Kish, A. W., and Ziherl, L. A.: Large Scale Administration of Vaccines bv Means of an Automatic Jet Iniection Syringe. J. A. M. A. 157: 633. 1955. 8. Ku&her, h. M., and Zegarelli, E. V.: An Intra:oralJet Injection Technique: Clinical Impression, N. Y. J. Dent. 35: 219, 1965. 9. Epstein, 5. : Pressure Injection of Local Anesthetics: Clinical Evaluation of an instrument, J. Am. Dent. Assoc. 82: 374, 1971. 10. Arefian, D., Henry, J. L., and Whitehurst, V.: Clinical Evaluation of a Syringe-Loaded Gun, ORAL SURG.~~: 168,1972. 11. Schmidt, D. A.: Anesthesia by Jet Injection in the Practice of Pedodontics, J. Dent. Child. 33: 340, 1966. 12. Bennett, C. R., and Monheim, L. M.: Production of Local Anesthesia by Jet Injection,
ORAL SURG.32: 526,1971. 13. Garellek, A. L.: Clinical Evaluation of a Jet Injector for Local Anesthesia, J. Can. Dent. Assoc. 33: 329, 1967. 14. Stephens, R. R., and Kramer, I. R. H.: Intra-oral Injection by High Pressure Jet, Br. Dent. J. 117: 465, 1964. 15. Whitehead, F. I. H., and Young, I.: An Intra-oral Jet Injection Instrument: An Histological, Bacteriological and Clinical Assessment, Br. Dent. J. 125: 437, 1968. 16. Bennett, C. R., Mundell, R. D., and Monheim, L. M.: Studies on Tissue Penetration Characteristics Produced by Jet Injection, J. Am. Dent. Assoc. 83: 625, 1971. 17. Bell, W. A., Kimble, A, Traeger, K. A., and Hanson, L. S.: Histologic Evaluation of a Jet Injection of 2 Per Cent Lidocaine Solution on the Oral Mucosa of a Mixed-Breed Dog. A Review and Experimental Study, ORAL STJRG.31: 79, 1971. 18. Pease, D. C.: Histological Techniques for Electron Microscopy, ed. 2, New York, 1964, Academic Press. Inc.. D. 23. 19. Clynes, J. T.: The Path of Inflammation Into the Supporting Structures, Thesis, Boston University School of Graduate Dentistry, 1972. 20. Ikehara, N. K., McKibben, D. H., Pechersky, J. L., and Rapp, R,.: Comparison of Jet Injection and Needle-Syringe Injection Techniques in Production of Edema, J. Dent. Res. 51: 573, 1972. 21. ~~$c~$~~., and Norris, W.: Skin Fragments Removed by Injection Needles, Lancet 2: 22. Ca&um, R. A.: The Implantation of Cells From the Oral Mucous Membrane by Injection Needles, Arch. Oral Biol. 1: 206, 1959. 23. Thompson, N.: A Clinical and Histological Investigation Into the Fate of Epithelial Elements Buried Following the Grafting of “Shaved’, Skin Surfaces-Based on a Study of the Healing of Split-Skin Graft Donor Sites in Man, Br. J. Plast. Surg. 13: 219, 1960. 24. Williams, W. L., and Frantz, M.: Histologic Techniques in the Study of Vitally Stained Normal and Damaged Cells, Anat. Rec. 100: 547, 1948. 25. Williams, W. L.: Studies of Vitally Stained Normal and Damaged Cells (Abstr.), Anat. Rec. 100: 723, 1948. 26. Stallard, R. E., and Schaffer, E. M.: Vital Staining of the Periodontium of White Mice, J. Periodontol. 8.3: 183, 1962. Reprint requests to : Dr. A. K. ElGeneidy Clinical Research Center Boston University School of Graduate 100 East Newton St. Boston, Mass. 02118
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