RU2195709C1 - Method for simulation of surgical wound - Google Patents

Abstract

FIELD: medicine, experimental surgery, applicable in simulation of a surgical wound. SUBSTANCE: linear dermal wound is applied. A wound canal is made by puncture of the subcutatenous fat muscular layer by a thick needle. A sutural thread is passed through the needle in the presence of a dosed out microbic contamination. The dermal wound is laced up layer by layer. EFFECT: avoided additional wound contamination.

Description

 The invention relates to medicine, in particular to the field of experimental surgery, to methods for modeling surgical wounds, both aseptic and freshly infected, and can be used to study the various properties of surgical suture threads, both conventional and antimicrobial, under dosed or without microbial contamination her.

 In experimental surgery, depending on the tasks and the proposed methods for their solution, the conditions of ideal or aseptic wounds and surgical wounds that are closest to the clinical ones are simulated with all their mandatory components consisting of tissue trauma, the presence of devitalized tissues in the wounds, layer-by-layer suturing of wound sutures , ischemia of tissues with sutures, infection of wounds with various types of pathogenic microorganisms, etc.

 Regarding aseptic wounds, the following considerations may be made. According to the literature, any experimental wound from the moment of its creation cannot be aseptic, since under normal conditions it is impossible to avoid contact of its surface with the environment, and hence with many microorganisms inhabiting it, many of which are pathogenic.

 Microbiological studies conducted by A.V. Volenko, showed that the incidence rate of experimental primary aseptic wounds is 30.0 ± 10.3% / Volenko A.V. Prospects and opportunities for preventive washing of surgical wounds with pulsating jets of fluid under pressure. Surgery 1998, 4 p. 46-50 /.

 Morphological and microbiological studies conducted by him in studying the causes of wound postoperative complications in experimental models of surgical wounds and developing ways for their targeted prevention showed that the morphofunctional substrate of the wound plays a decisive role in the etiology of wound complications, the main component of which, in addition to the nature of the wound, is the degree trauma and ischemia of paravular tissue, the presence of devitalized tissues in the wound, properties and amount of suture material la, the nature and degree of microbial seeding, the nature of the seams, etc. / Volenko A.V. Prevention of postoperative wound complications. Surgery 1998, 9, p. 65-68 /.

According to the author, the isolated presence of one of these factors in the wound in most cases does not lead to the development of wound postoperative complications. Thus, infection of wounds even with supercritical doses of monocultures of pathogenic microorganisms and their associations does not necessarily cause the development of wound infection. The “critical dose” of microorganisms necessary for the development and progression of an infectious process in a wound and, according to the literature, amounts to 10 ₅ -10 ₆ colony forming units / CFU / per 1 g of tissue, cannot be considered a mandatory factor for fresh wounds, but in conjunction with injury tissues, the presence of devitalized tissues, suture material, tissue ischemia, wound infection leads to suppuration, the morphological features of which are determined by the nature of the microflora.

 At the same time, quantitative microbiological studies conducted by him in a group of animals with tissue ischemia with constricting sutures showed that in this case a quick spontaneous infection of paravular tissues with Staphylococcus aureus and Proteus occurs. Starting from the 3rd day after the operation, the seeding of primary aseptic wounds with tissue ischemia practically corresponds to that of wounds infected with supercritical doses of microorganisms.

 The most important in the development of postoperative wound complications belongs to the quality and quantity of suture material. In their classic studies, Flek and Conen showed that a ligature placed in a suspension of 10 microbial cells / ml and then implanted under the skin also causes suppuration of the wound. / Flek and Con. Br G Exp Pathol 1957, 38, p. 573 /.

 Based on this study, the concept of the importance of a foreign body in the pathogenesis of a wound infection process was put forward. / Shevola D., Dmitrieva N.V. Antibiotic prophylaxis in medical practice. M.ZAO "Print-Partner" 2000, p.21 /.

 According to I.A. Yerukhin, in clinical surgery the very probability of developing a wound infectious process, its severity, clinical features and prognosis depend to a decisive extent on the factors that determine the conditions for the interaction of the host organism and microflora, on how these conditions contribute to the onset and progressive development of the infection. And far from always in this case, the aggressiveness of the pathogen acts as a decisive factor. Much more often, the premorbid situation that provokes the infectious process is created by disturbances in the vital activity of the host organism, by its reaction to extreme external influences. And the choice of pathogen is secondary and depends on these priority factors. / Yerukhin I.A. Infection in surgery. An old problem on the eve of the new millennium. Herald of Surgery 1998, 1, pp. 85-91 /.

 Various methods are known for modeling the conditions of surgical wounds in an experiment.

 So, I.D. Zhitnyuk to clarify the osmotic effect of the powder developed by him, each experimental animal (rabbit) inflicted softened skin and muscle wounds of the same size on both sides of the spine. The bactericidal properties of the powder were tested in an experiment on animals (rabbits), which were inflamed with skin-muscle wounds in the gluteal region and 1 billion microbial cells of Staphylococcus aureus were infected with them.

 To resolve the issue of the possibility of using powders I.D. Zhitnyuk for lengthening the period of primary surgical treatment of soft tissue wounds V.P. Petrov conducted experimental studies on 120 animals (rabbits), which were applied on the gluteal area with softened skin and muscle wounds measuring 6.0 x 3.0 cm. Wounds infected 1 billion cells of the daily culture of Staphylococcus aureus or 0.5 grams of garden soil, and then sutured by suturing the skin. / Zhitnyuk I.D. Treating infected wounds with a powder mixture. Herald of Surgery 1967, 12, p. 69-74 /.

 When developing and testing antimicrobial surgical suture materials, Yu.A. Furmanov under anesthesia (intraperitoneal administration of a 5% solution of Nembutal) in experimental animals (rabbits and white rats) performed incisions of the skin and subcutaneous base on the back parallel to the spine, freely implanted cuts of antimicrobial suture threads subcutaneously and sutured the skin wound / Furmanov Yu.A., Gorshevikova E .V., Adamyan A.A., Vinokurova T.I., Tsetlin B.L., Vlasov A.V., Silkis E.M., Moshkovsky G.Yu. Development and testing of surgical suture materials. Clinical Surgery 1985, 3, pp. 25-28 /.

 When studying the effect of surgical suture material, especially material from biologically active fibers, on the course of the wound infection process in the General Surgery Clinic of MMA named after THEM. Sechenov's experimental studies were carried out on animals (guinea pigs), which under aseptic conditions in the interscapular region were inflicted with a linear wound 5.0 cm long, various microbial cultures were introduced into it, and then the skin wound was sutured with the studied samples of suture threads. / Tolstykh P.I., Harutyunyan B.I., Struchkov Yu.V. , Vasilkova Z. F. ,, Krasovskaya S.B., Belyaeva O.A., Kildeeva N.R. Biologically active suture material as a means of preventing wound healing disorders. Surgery 1980, 5, p. 108-113 /.

 A similar model of a surgical wound was used by V.K. Gostischev and S.S. Oganesyan in order to justify the methods of surgical intervention and the development of complex and etiotropic therapy of non-clostridial infections of soft tissues in the case of local anaerobic non-clostridial infections / Gostischev V.K., Oganesyan S.S. Features of the clinic, diagnosis and treatment of non-clostridial anaerobic infections of soft tissues. Surgery 1989, 10, p. 155-157 /.

 In studying the causes of wound postoperative complications in experimental models of surgical wounds and developing ways for their targeted prevention A.V. Volenko used white Wistar rats of both sexes. Under anesthesia and following aseptic rules, all animals were inflicted with skin-subcutaneous-muscle wounds 4 cm long on the back. Wound tissues were injured with a hemostatic clamp, a piece of silk ligature 1 cm long and a section of crushed fiber 0.2 x 0.2 cm in size were introduced into the wound. In all cases, the skin edges of the wounds were sutured with 3 silk sutures tightly. / Volenko A.V. Prospects and opportunities for prophylactic washing of surgical wounds with pulsating jets of fluid under pressure. Surgery 1998, 4, p. 45-50 /.

 In all the methods of modeling the conditions of surgical wounds described above in an experiment, there are certain disadvantages that affect the reliability of the assessment of the results obtained, especially with a qualitative and quantitative consideration of their microbial contamination.

 So, when simulating the conditions of a surgical wound, reproducing one of its most important components, mechanical trauma, it is practically impossible to calculate in each specific case the force of the traumatic effect created by the researcher's hands (softening the tissues or traumatizing them with a hemostatic clamp).

 Free implantation into the wound of the test thread excludes tissue ischemia with constricting sutures, in which there is a rapid spontaneous infection of paravular tissue. The very presence of sutures in the wound increases its microbial contamination by 10,000 times. The quality and quantity of suture material, as well as additional wound contamination with various strains of nosocomial infection pathogens, which occurs not only during the experiment, but also in the postoperative period, in the healing process of the skin wound sutured by the thread, due to its inherent fit, are not taken into account.

 Of all the analogues described in the literature on the closest technical nature, as a prototype, we selected the Edlish RF method for modeling the conditions of a surgical wound, which consists in dissecting the skin and subcutaneous muscles of female Surris-Webster mice in the paravertebral region, introducing pathogenic suspensions into the center of the wound microbes and suturing the wound with a suture drawn through all layers (skin, muscles), with the formation of a node on the skin. / Edlish R.F., Panek P.P., Rodeheaver G.T., Tunbull W.C., Kurts L.D., Edgertion M. T. Phisical and chemical configuration of suture in the development of suture infection. Ann Surg. 1973, 177. p.679-687. Viliam V. Sharp, M. D.; Terry A. Belden, B.S .; Pete H. King, B.S. and Phillip C.Teague, B.S. Suture resistents to infection. Surgery 1982, 1, p. 61-63 /.

 Using this technique, the author managed to avoid all of the above disadvantages, except for additional wound contamination by the nosocomial microbial association. Its negative point is the partial loss of mass of the suture during the formation of a node on the skin.

 The objective of the invention is to develop a method for modeling the conditions of a surgical wound, avoiding additional contamination of the wound and thereby increase the reliability of the results.

 The problem is solved in that the wound canal is created using a soft tissue puncture with a thick needle, through which a suture is carried out in the presence of metered, microbial contamination, and the wound is sutured in layers.

 The method is as follows.

 To simulate the conditions of a surgical wound, sexually mature male guinea pigs weighing 250-300 grams are used.

 All laboratory animals come from one source. They are quarantined for 2 weeks before research and receive standard laboratory food (cereals on water, vegetables, fruits) and drink (water, milk). An identical diet and diet are observed throughout the experiment.

 Anesthesia during surgical intervention is carried out by the introduction of an intraperitoneal narcotic mixture consisting of 0.5 ml of a 2% solution of promedol, 0.25 ml of a 2% solution of chlorpromazine and 0.25 ml of a 2% solution of diphenhydramine (the qualitative and quantitative composition of the drug mixture was selected empirically) .

 The animal is prepared for surgery by clearing a patch of skin in the scapular area on the one side 6.0 x 2.0 cm from the hair and treating the surgical field with a 1% iodine solution (a higher concentration of iodine solution penetrates the skin covering, staining muscles, and, in our opinion, affects the "purity" of the experience, causing a chemical burn of tissues).

 Then, under aseptic conditions in the paravertebral region, a linear skin wound with a length of 5.0 cm is applied with a scalpel on one side of the guinea pig.

 To create a wound channel, a hypodermic base (subcutaneous fatty tissue, muscle layer) is punctured through its entire thickness with a Dufo needle, through which a suture thread and a thin needle 90 mm long are parallel to it / Injection needle for Record syringes 1 A 1-0 , 8 x 90-1 15 /, after which the Dufot needle, which created the wound channel, is removed.

 Then, a thin needle is removed from the newly created wound canal with the simultaneous injection of 1 ml of physiological saline with a microbial monoculture or microbial association into it using a syringe.

 The thread in the wound canal is fixed by a nodal suture on top of the subcutaneous layer. The skin wound is sutured with single interrupted sutures with an interval of 1.0 cm from each other and closed by applying SBV-14 film.

 In the postoperative period, dynamic monitoring of the condition of the skin postoperative wound is conducted. In terms dictated by the task before the experiment, the animal is slaughtered and excised under aseptic conditions of the area of the studied tissues with a model of the wound canal.

 After surface washing of the test fragment with sterile physiological saline, it is cut along the wound canal with a biopsy sample of the wound bottom for a qualitative and quantitative assessment of the microbial contamination of the wound canal.

 The wall of the wound canal and tissue are examined histologically at a distance of 5.0 and 15.0 mm around it to study the depth of spread and the severity of the inflammatory reaction of paravular tissues, which is evaluated on a generally accepted 5-point scale.

 Modeling the conditions of the surgical wound by our proposed method allows us to avoid additional contamination of its surface by nosocomial infection pathogens as a result of the absence of contact of the wound surface with the environment.

This condition is achieved by the fact that the wound surface is created by puncturing with a thick needle located subcutaneously uninfected soft tissues in a minimally short time,
At the same time, all the conditions for modeling a surgical wound, which consist in inflicting a metered injury to the soft tissues with a Dufo needle while creating a wound canal by puncture, the presence of devitalized tissues, hematomas and sulfur after removing a thick needle from it, are preserved; infection of the wound channel with various strains of pathogenic microbes and their associations, and especially layer-by-layer suturing of the wound with suture material with the formation of nodes subcutaneously on top of the soft tissue base, in which there is no loss of mass of suture material and ischemia continues with sutures of paravular tissues.

 Modeling the conditions of a surgical wound by creating a wound canal allows not only to avoid additional contamination of the wound surface with pathogenic microflora, but also to infect it with strictly regulated doses of pathogenic microbes and their associations, which positively affects the reliability of qualitative and quantitative indicators of microbiological research data obtained by studying the dynamics the development of a wound infection process under given conditions.

 Example 1

 The experimental animal is a guinea pig weighing 275 grams. Anesthesia is carried out according to the usual method. The conditions of the surgical wound were modeled by our proposed method by creating a wound channel.

 A guinea pig under aseptic conditions in the paravertebral region, on one side, a 5.0 cm long linear skin wound was applied with a scalpel parallel to the spine. Perpendicular to it, in the direction transverse to the muscle fibers, by piercing the subcutaneous base through the entire thickness with a Dufo needle, 2.0 cm long, a wound channel has been created with all the components characteristic of a surgical wound. A suture thread (surgical nylon 3) was held through the wound channel, which is fixed on top of the muscle layer with the formation of 3 nodes. The skin wound was sutured with single interrupted sutures with an interval of 1.0 cm from each other and closed by applying SBV-14 film. Before the last suture is applied to the skin, microbial contamination of the wound is single colony-forming microbes in the field of view. The operation time is 7 minutes.

On 1 day after the operation, there were no signs of inflammation in the wound canal; there is a mucous effusion in a small amount. The microbial contamination of the wound canal zone is 1-2 CFU / cm ² , it corresponds to the microbial contamination of the subcutaneous wound. A histological examination showed a minimal inflammatory reaction from the paravular tissue, characterized by a slight expansion and overflow of blood of individual vessels and the presence of individual leukocytes in the perimisium. Inflammatory reaction from the side of paravular tissues is estimated at 1 point.

On the 4th day after the operation, there were no signs of inflammation in the wound; there is a small amount of mucous effusion in the wound channel. Microbial contamination of the wound channel, as well as the subcutaneous wound, is 2-3 CFU / cm ² . A histological examination reveals a slight inflammatory reaction, characterized by the expansion and overflow of blood of microvessels, uniform perimetic infiltration with leukocytes, the absence of necrotic foci and the growth of granulation tissue in the defect zone. Inflammatory reaction from the side of paravular tissues was rated at 2 points.

 Example 2

The experimental animal is a guinea pig weighing 290 grams. The modeling of the conditions of a surgical wound was made by our proposed method by creating a wound channel. Microbial contamination of the wound canal zone was carried out with a monoculture of Staphylococcus aureus aureus at a dose of 10 ₈ / ml (a monoculture of Staphylococcus aureus in a quantity of 10 ₈ microbial cells in 1 ml of physiological saline was introduced into the wound canal). Microbial contamination of the wound before suturing was 1-2 CFU / cm ² .

On the first day after surgery, moderate inflammation was noted in the wound canal with exudation of paravular tissues and the presence of a significant mucous effusion in it. Microbial contamination of the wound canal zone was 4-5 CFU / cm ² , subcutaneous wounds - 1-2 CFU / cm ² . A histological examination revealed a pronounced inflammatory reaction in paravular tissues - in the expanded and blood-filled microvessels, a distinct marginal standing of neutrophils and a high degree of perimisy infiltration by leukocytes are noted, there are separate small foci of necrosis that do not merge into large ones. The wound channel with adjacent dystrophically altered tissues is separated from normal by a granulation tissue rich in histiocytes. Inflammatory reaction from the side of paravular tissues was rated at 4 points.

 Example 3 (prototype method).

 The experimental animal is a guinea pig weighing 265 grams. Anesthesia is carried out according to the usual method. The modeling of the conditions of the surgical wound was made according to the prototype method without microbial contamination.

Guinea pig under aseptic conditions in the paravertebral region, on one side, a linear skin wound 5.0 cm long was applied with a scalpel parallel to the spine. The subcutaneous base (subcutaneous fatty tissue, muscles) was dissected by a linear incision 2.0 cm long, which corresponds to the length of the wound channel created by the needle Dufault, in our proposed method. Subcutaneous tissue is injured by a hemostatic clamp, after which a nodal suture is drawn through all layers (skin, subcutaneous base) of a surgical nylon 3 with the formation of a node on the skin. The rest of the skin wound is sutured with 4 single interrupted sutures with an interval of 1 cm from each other and is closed by applying SBV-14 film. Before applying the last suture to the skin, the microbial contamination of the wound was 1-2 CFU / cm ² . The operation time from the moment of applying the skin wound to the last suture is 20 minutes.

On 1 day after the operation, there were no visual signs of inflammation in the wound, there was a slight mucous effusion in a small amount. Microbial contamination of the wound was 4-5 CFU / cm ² . Histological examination showed a slight inflammatory reaction, characterized by the expansion and overflow of microvessels with blood and uniform perimetic leukocyte infiltration. The severity of inflammation is estimated at 2 points.

On the 4th day after surgery, signs of inflammation are visually observed in the wound - moderate exudation of paravular tissues and a significant amount of mucous effusion. Microbial contamination of the wound was 10-12 CFU / cm ² . Histological examination shows a distinct marginal standing of neutrophils in blood vessels as a stage of migration of blood cell elements into the surrounding connective tissue, occasionally there are foci of necrosis, the growth of granulation tissue rich in histiocytes. The severity of inflammation is estimated at 3-4 points.

 Example 4 (prototype method).

The experimental animal is a guinea pig weighing 300 grams. Anesthesia, modeling of the conditions of a surgical wound and its suturing were performed according to the prototype method. Microbial contamination - a monoculture of Staphylococcus aureus in an amount of 10 ₈ CFU / ml. Microbial contamination of the wound before the last suture was 4-5 CFU / cm ² . The operation time is 20 minutes.

On the first day after the operation, the wound showed signs of moderate inflammation - edema of paravular tissue and turbid mucous effusion in significant quantities. Microbial contamination of the wound was 10 CFU / cm ² . During histological examination in the expanded microvessels, a distinct edge standing of a large number of neutrophils is noted. Foci of necrosis and proliferation of granulation tissue are absent. The severity of the inflammatory reaction is 3 points.

On the 4th day after the operation, a picture of severe inflammation is noted in the wound - a significant turbid effusion and exudation of paravular tissue. Microbial contamination of the wound - 2 x 10 ₃ CFU / cm ² . Histological examination revealed the highest degree of severity of the inflammatory reaction - a pronounced reaction from the vascular bed, a high degree of infiltration of the connective tissue layers, the presence of numerous foci of necrosis, often merging into one large one. The severity of the inflammatory reaction is 5 points.

 Thus, the qualitative and quantitative indicators of microbial contamination significantly differ in cases of modeling the conditions of surgical wounds according to the prototype method and according to the claimed method, which from the first days determines the nature of the course of the wound infection process and the type of healing of the surgical wound, primary or secondary, through suppuration and granulation tissue formation. Our studies confirm the concept of I. A. Eryukhin that the development of a wound infection process depends entirely on the initial conditions provoking its occurrence.

 The use of an experimental simulation of the conditions of surgical wounds in the prototype method did not allow us to empirically select the optimal dose of an antiseptic introduced into the thread to give it antimicrobial properties that can effectively inhibit the growth of pathogenic microflora in the wound without exerting a toxic effect on paravular tissue.

 By modeling the conditions of surgical wounds by creating a wound channel, it was possible not only to reproduce all their inherent components, such as dosing trauma to soft tissues, the presence of devitalized tissues, hematomas, and seromas in wounds; infection of the wound surface with various strains of pathogenic microbes and their associations; layer-by-layer suturing of wounds with suture material without loss of mass during the formation of nodes; ischemization of paravular tissues, but also to avoid additional contamination of the wound surface with pathogenic microflora due to its isolation from the environment and reduction of the time of surgical intervention, which in the conditions of dosed microbial contamination with “critical doses” of pathogenic microbes and their associations made it possible to increase the reliability of qualitative and quantitative indicators of microbiological research .

 It should also be noted that the method of modeling the conditions of a surgical wound by creating a wound channel is universal. It can be reproduced on any experimental animals in any part of their body, and the localization of the wound channel, its length and degree of microbial contamination depend on the conditions of experimental studies and the chosen ways to solve the problems.

 In our case, modeling the conditions of the surgical wound by the claimed method allowed us not only to predict the nature of the course of the wound infectious process and the type of healing of the postoperative wound, but also to select empirically the maximum permissible concentration of antiseptic in the suture thread, which effectively suppresses the growth of pathogenic microflora in the wound during the healing process, and subsequently to carry out the production release of experimental batches of antimicrobial suture threads used in practical surgery.

Claims (1)

 A method of modeling the conditions of a surgical wound by creating a wound surface and suturing it with suture, characterized in that a linear skin wound is first applied, then a wound canal is created by piercing the subcutaneous fat, muscle layer with a thick needle, through which the suture is carried out in the presence of dosed microbial contamination after which the skin wound is sutured in layers.