John G. Thacker

Cleansing the traumatic wound by high pressure syringe irrigation

The purpose of this study was to examine the influence of the fluid dynamics of syringe irrigation on the efficacy of wound cleansing and the infection rate of experimental wounds. The pressure experienced by a surface following wound irrigation was directly proportional to the pressure within the syringe and the size of the needle. High pressure syringe irrigation effectively removed bacteria from the surface of the wound. This reduction in the wound bacterial count resulted in a decrease in the infection rate of tissues. Low pressure irrigation with an asepto syringe did not significantly cleanse the wound of its bacterial contaminants and had no demonstrable clinical merit. On the basis of these studies, high pressure syringe irrigation is being employed routinely in our emergency department for the care of traumatic wounds.

Principles of emergency wound management

Every traumatic wound treated in the emergency department is a result of a finite energy source that caused tissue disruption. The dynamics of this exchange of energy will determine the magnitude of injury. Disruption of the body covering leaves the once-sterile underlying integument exposed to contamination. The contaminants are derived from either the victim (endogenous) or the exogenous energy source. The presence of a contaminant such as bacteria makes the care of the wound an exercise in microbiology. Other contaminants, such as dirt, also may reside in the recesses of the wound. Emergency physicians must understand the consequences of tissue trauma. A study of the mechanism of injury will provide a reliable indication of damages. Whether the tissue injury will be limited to the initial wounding depends on the outcome of the interaction between the contaminants and the wound. In the event that the contaminants are very reactive, a relatively insignificant wound may become a catastrophe. This circumstance can be averted by the implementation of a well-devised plan based on the biology of wound healing and infection.

Mechanical performance of surgical sutures.

A comprehensive analysis of the mechanical performance of sutures has been made to provide information concerning the reliability and security of knotted sutures. The tests utilized in this analysis were designed to be easily reproduced by other investigators. The construction of the knot and the knot performance analysis were undertaken utilizing an Instron Tensile Tester. The mechanical reliability of each knotted suture was determined by measuring the number of throws to reach knot break, the expected slippage of the knot when it reaches knot break, and the maximal holding force at knot break. On the basis of these measurements, recommendations are made for the use of a suture at operation.

Bioengineering principles of hydrotherapy.

Hydrotherapy is based on several important bioengineering principles that permit the design and development of aquatic exercise devices, techniques and programs. These principles involve several forces (buoyancy, drag, inertia), hydrostatic pressure and the specific heat of water. By acquiring a knowledge of these bioengineering principles, an individualized exercise program can be prescribed that will enhance physical fitness which is associated with desirable psychological changes.

Mechanical cleansing of contaminated wounds with a surfactant

Mechanical cleansing of a wound with a sponge soaked in a surfactant has prevented the development of experimental wound infection. The surfactant utilized for wound cleansing is Pluronic F-68, a member of a family of block copolymers called Pluronic polyols. Long-term toxicity studies and clinical trials suggest that this surfactant is safe for human use. Pluronic F-68 is a nonionic detergent that does not have any intrinsic antibacterial activity. Although mechanical cleansing with saline-soaked sponges effectively removes bacteria, it damages the wound and impairs its resistance to infection. The severity of the damage to the skin exerted by the sponge can be correlated with its porosity. Sponges with a low porosity are abrasive and exert more damage to skin than do sponges with a higher porosity. The addition of Pluronic F-68 to even the most abrasive sponges ensures that the bacterial removal efficiency of the sponge scrub is maintained, while tissue trauma is minimized. This dual effect of the surfactant results in a dramatic reduction in the infection rate of contaminated wounds. On the basis of these results, a clinical trial with surfactant-soaked sponges would appear to be indicated.

Wheelchair tire rolling resistance and fatigue.

The hysteresis loss theory of rolling resistance is developed for solid rubber wheelchair tires. The analysis is used to correlate test data for a clay-filled natural rubber and a polyurethane tire material. A discussion of tire rolling work, hysteresis loss factor measurement, and rolling loss measurement is presented. An example calculation of rolling resistance for a polyurethane tire is given in detail. The subject of solid rubber tire design is developed on the basis of recommended fatigue life theory and practice. It is shown that polyurethane tires have a useful fatigue life due to a high shear modulus at useful values of hardness. This characteristic of polyurethane, if exploited, is predicted to lead to a tire with a lower rolling resistance than other wheelchair tires available. The effect of surface roughness on rolling resistance is briefly discussed and some experimental results are listed. The purpose of this paper is to give the rehabilitation engineer the means for wheelchair tire rolling resistance and fatigue life design and the methods to assess the tire characteristics when a tire design is modified or a new tire material is contemplated. Other important design factors, such as wear and chemical degradation, are not discussed, but references are suggested for information on these topics. As in most research and development projects, this study raises problems which need further work. For example, the fatigue properties of the rubber compounds employed in this application are not completely understood; this subject is planned for future investigation.

REVOLUTIONARY ADVANCES IN THE MANAGEMENT OF TRAUMATIC WOUNDS IN THE EMERGENCY DEPARTMENT DURING THE LAST 40 YEARS: PART I

BACKGROUND AND OBJECTIVES This report provides an overview of advances in wound repair devised by our research team during the last four decades. This collective review is presented in two parts. DISCUSSION The following components are included in Part I: 1) search and treat life-threatening trauma; 2) conduct a thorough history; 3) examine the wound using aseptic technique; 4) anesthetize the wound before cleansing; 5) hair removal, skin disinfection, hemostasis, surgical debridement, and mechanical cleansing; 6) antibiotics, drains, and open wound management. CONCLUSION On the basis of these comprehensive research studies, we have noted a marked reduction in the incidence of wound infection in traumatic wounds.

Mechanical performance of monofilament synthetic absorbable sutures.

The purpose of this study was to evaluate the mechanical performance of two new synthetic monofilament absorbable sutures. The polydioxanone sutures is prepared by polymerizing and extruding the monomer, paradioxanone, in the presence of a suitable catalyst. The other suture is a modified polyglycolic acid suture, made by reacting trimethylene carbonate and glycolide. The knot configuration (1 = 1 = 1, 1 x 1 x 1, and 2 = 1 = 1) required for knot security was identical for the two synthetic monofilament sutures. The mean knot breaking strengths for the polydioxanone and modified polyglycolic acid sutures did not differ significantly. The surfaces of these sutures exhibited a low coefficient of friction which was slightly increased by hydration. The most distinctive difference between the handling characteristics of these two sutures was their flexural rigidity. The stiffness of the polydioxanone suture was 60 percent greater than that of the modified polyglycolic acid suture.

Knotting and handling characteristics of coated synthetic absorbable sutures

The purpose of this study was to evaluate the knotting and handling characteristics of the new coated synthetic absorbable sutures. When compared to the coated polyglactin 910 sutures, the coated polyglycolic acid sutures displayed a lower coefficient of friction, encountered less tissue drag forces, and exhibited less flexural rigidity. In the case of sizes O, 2-O, and 3-O coated polyglycolic sutures, knot security was achieved with one less throw than with similar sizes of coated polyglactin 910 sutures. On the basis of these comprehensive mechanical performance tests, the knotting and handling characteristics of the coated polyglycolic acid sutures were judged to be superior to that of the coated polyglactin 910 sutures.

Influence of knot configuration and tying technique on the mechanical performance of sutures

The purpose of this investigation was to determine the influence of knot configuration and tying technique on the mechanical performance of surgical sutures. Multifilament and monofilament nylon sutures were selected for this evaluation because they are commonly used in wound closure. The mechanical performance of these sutures was judged by the following parameters: knot breakage force, configuration of secure knots, and knot run down force. During each test, tension was applied at either rapid or slow rates, which correlates with the physicians speed of tying knots. On the basis of these mechanical performance tests, four throw square (1 = 1 = 1 =1) knots and five throw square (1 = 1 = 1 = 1 = 1) knots are recommended for monofilament nylon and multifilament nylon sutures, respectively, in which the speed of application of forces to the knots is relatively slow. Because these tests can easily be replicated in any laboratory, manufacturers now have a scientific basis for recommending specific tying techniques for their surgical sutures.