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Wound irrigation
Editorial
Wound Irrigation Richard F Edlich,MD, PhD Department of PlasticSurgery University of Vir~nia MedicalCenter Charlottesville,Vir~nia
Wound Irrigation
John G Thacker, PhD Department of Mechanicaland Aerospace Enffmeering University of Virffmia MedicalCenter Charlottesville,Vir~nia
Twenty-five years have elapsed since our team of scientists demonstrated that wound irrigation delivered under low pressure was ineffective in preventing the development of wound infection. 1 Our observations were consistent with the results of earlier studies confirming the ineffectiveness of low-pressure wound irrigation. 2-s When we applied the principles of fluid dynamics to wound irrigation, we realized that the bacterial removal efficiency of irrigation would improve as the pressure at which the fluid was delivered to the wound was increased. 6 An irrigation assembly was constructed to deliver saline at varying pressures to a contaminated wound. The saline reservoir was pressurized by a CO 2 cartridge and adjusted to either 0.5 or 25 psi. This irrigation assembly delivered either a continuous or pulsatile irrigating stream of saline. Raising the delivery pressure of the irrigating stream markedly increased its bacterial removal efficiency and significantly reduced the incidence of bacterial infection. As expected, low-pressure irrigation had insignificant therapeutic merit. Furthermore, the results of our studies indicated that high-pressure irrigation must be continuous to have the mammal bacterial removal effect. The superiority of continuous flow over pulsatile flow in wound decontamination may be related to a time-dependent force, which is especially important in liquid systems. It was postulated that a strong force must be applied to bacteria for a protracted time to dislodge them from the wound. The continuous-flow jet appeared to provide the necessary duration of contact between the irrigating medium and the bacteria for effective wound decontamination. These high-pressure irrigation systems had been used primarily in operating rooms and were rarely used in emergency departments. They are designed primarily for
88
Seerelatedarticle, p 36. [Edlich BF,ThackerJG: Wound irrigation. Ann EmergMedJuly
1994;24:88-90.]
ANNALS OF EMER6ENCY MEDICINE 24:1 JULY 1994
EDITORIAL
cleansing large wounds, which are rarely encountered in emergency medicine practice. Consequently, we searched for and developed a practical alternate approach for use in the ED. Our new irrigating system used a commercially available syringe and needle to deliver the irrigant to the wound, r We derived analytically the maximum pressure experienced by a wound surface as the result of irrigating streams delivered by different needle syringe assemblies. The maximum pressure experienced by the tissue from an irrigating stream exiting from a needle was derived from the well-known Bernoulli's equation. A reservoir maintained under a measured static pressure was used to reproduce the conditions of the irrigant inside the syringe barrel. Exit irrigant velocities for each needle over a wide range of syringe barrel pressures were used to calculate the maximum pressures experienced by the wound surface. We then correlated these maximum static pressures to the conditions within the syringe barrel resulting from the physician pressing on the plunger. The average force exerted on the syringe plunger was determined with a pinch meter placed between the physician's thumb and plunger, which simulated syringe irrigation using o n e hand. With the physician's ring and index fingers grasping the concentric ring surrounding the syringe barrel end, the thumb pushed the plunger into the barrel. Two finger rings have been attached to the barrel of some disposable syringes to enhance the security of the physician's grasp of the syringe barrel. The pressure also was measured directly with the bulb syringe using a pressure transducer. The measured pressure within a 35-mL bulb syringe barrel attached to a 19-gauge needle was 19 psi, while the pressure within the bulb of the bulb syringe was only 5 psi. The pressures experienced by the wound surface from the fluid delivered by either the syringe assembly or bulb syringe were proportional to the pressures within these irrigation devices. The pressure experienced by a wound surface from fluid delivered from a 19-gauge needle and 35-mL syringe was 7 psi. In contrast, the pressure encountered by a surface irrigated by a bulb syringe was only 0.5 psi. The marked decrease in pressure from that encountered in the syringe barrel (19 psi) to the pressure experienced by the wound surface (7 psi) was caused by the frictional forces in the needle. For all treatments, the tip of either the needle or bulb syringe was placed as close as possible to the surface of the wound. The bacterial removal efficiency of the irrigating stream was proportional to the pressure experienced by the wound surface. High-pressure irrigation with a 35-mL
JULY 1994
24:1 ANNALS OF EMER6ENOY MEDICINE
syringe attached to a 19-gauge needle operated manually by one hand effectively decreased the level of bacterial contamination. The cleansing effect of the bulb syringe irrigation was negligible because the wound bacterial concentration was not significantly affected by this lowpressure irrigation system. High-pressure syringe irrigation markedly reduced the incidence of wound infection in contaminated wounds; bulb syringe irrigation did not alter the infection rate. Continuous high-pressure irrigation is also an effective means of removing soil infection-potentiating factors in dirt from the wound. 8 High-pressure irrigation removed 80% of the soil infection-potentiating factors from the wound. Changing the composition of the wound irrigant by adding chelating agents, flocculants and dispersants, or a nonionic surfactant did not significantly enhance the efficiency of removal of soil infection-potentiating factors in wounds. The benefits of high-pressure irrigation must be weighed against potential side effects. 9 Fears that pressure irrigation will disseminate bacteria into adjacent tissue area were unfounded. In our studies, high-pressure irrigation did not enhance the dissemination of bacteria into soft-tissue wounds. However, the irrigation fluid disseminated into the interstices of the wound, predominantly in a lateral direction. This lateral spread occurred within the loose areolar tissue, contributing to the development of postoperative edema. Concern that high pressure can damage tissue defenses was justified. High-pressure irrigation resulted in trauma to the wound, which made the wound more susceptible to infection. This finding serves to remind the emergency physician that this technique cannot be used indiscriminately and should be reserved for heavily contaminated wounds. Other investigators have expressed concerns about other potential complications encountered during highpressure syringe needle irrigation. Parkinson and Hirst 1° were concerned that an unguarded needle could be an invitation to inadvertent needle puncture of either an assistant or the patient. They advocated covering the needle with a malleable plastic sheath. We prefer a 19-gauge, blunt-ended plastic catheter rather than a metal needle. The occupational risk to the emergency physician of exposure to HIV or hepatitis virus by virtue of accidental splashing of the irrigant has been another potential complication. 1E Several techniques, such as cupping the gloved hand around the wound and irrigating through the space between the thumb and index finger, have been recommended to reduce splatter. 12 Recently, a cuplike device has been marketed to prevent splatter while allowing irri-
89
EDITORIAL
gation with appropriate pressures. Because the device trapped the irrigant in the wound area, bacteria may be reintroduced into the wound. A simpler solution to this problem is to position the tip of the blunt-ended plastic catheter perpendicular to and in contact with the wound surface. This intimate contact of the catheter with the wound diminishes splashing and ensures that the maximum wound irrigation force is used to decontaminate the wound. Emergency physicians who do not follow directions and continue to position the catheter i to 3 cm above the wound surface should realize that the pressure at which the fluid contacts the wound will be diminished. Inadvertent splashing will present a serious and unnecessary occupational hazard. Our research on the fluid dynamics of wound irrigation that has spanned more than two decades has been a catalyst for the design and development of a wide variety of other high-pressure wound irrigation systems for use in the ED. In this issue of Annals, Singer and colleagues question whether these different irrigation systems are indeed high-pressure irrigation systems. By placing a pressure transducer immediately proximal to the needle hub, they were able to measure and monitor the pressure changes in the irrigation systems. All methods of irrigation yielded relatively square pressure tracings, with no significant pressure decrement over the 250-mL boluses. Singer et al's pressure measurements within the 35-mL syringe attached to a 19-gauge needle (median peak pressure, 35 psi; median trough pressure, 17 psi) were greater than the pressure (19 psi) within the same pressure irrigation system reported earlier by our laboratory. 7 This discrepancy may be attributed to the different techniques of manual irrigation used in the two studies. In their study, subjects manually applied pressure to the syringe using two hands; our physician manipulated the syringe assembly with only one hand. Because the force exerted on the syringe using two hands should be considerably greater than that applied by one, the pressures encountered within the syringe should be proportional to the magnitude of forces applied to the syringe. In our study, a pressure of 19 psi within the syringe appeared to be necessary for effective wound decontamination. On this basis, we would select irrigation systems that encounter comparable pressures within the syringe or container. On the basis of the pressure recordings reported by Singer et al, only the 65-mL and 35-mL syringes attached to 19-gauge needles should be considered for high-pressure wound irrigation in the ED.
90
1. EdlichRF, CusterJ, Madden J, et al: Studies in the managementof the contaminatedwound. III. Assessmentof the effectiveness of irrigation with antiseptic agents. AMJ Surg1969;118:3130. 2. FalconerB, Liljedahl SO, OlovsonT: On the effect of treatment of traumatic wounds with soap solution: An experimental study. Acta ChirScand1952;103:222-235. 3. Casten DF, Nach RJ, SpinziaJ: An experimentaland clinical study of the effectivenessof antibiotic wound irrigation in preventing infection. SurgGynecolObstet1964;118:783-787. 4. GingrassRP, CloseAS, Ellison EH:The effect of various topical and parenteralagents on the prevention of infection in experimentalwounds. J Trauma1964;4:763-783, 5. HopsonWB Jr, Britt LG, ShermanRT, et al: The use of topical antibiotics in the prevention of experimentalwound infection. J SurgRes 1968;8:261-266. 6. Madden J, EdlichRF, SchauerhamerR, et al: Applications of principles of fluid dynamics to surgical wound irrigation. CurrTopicsSurgRes 1971;3:85-92. 7. StevensonTR, ThackerJG, RodeheaverGT, et al: Cleansingthe traumatic wound by highpressure syringe irrigation. JACEP1976;5:17-21. 8. RodeheaverGT, Pettry D, ThackerJG, et al: Wound cleansingby high pressure irrigation. Surg GynecolObstet1975;141:357-362. 9. Wheeler CB, RodeheaverGT, ThackerJG, et al: Side-effects of high pressure irrigation. Surg GynecolObstet1976;143:775-778. 10. ParkinsonRW, Hirst P: A simple needle guard for low-volume, high-pressure irrigation, BrJ Accid Surg1990;21:128. 11. ChernofskyMA, Murphy RXJr, JenningsJF: A harrier technique for pulsed irrigation of cavitarywounds. PlastReconstrSurg1993;91:365-366. 12. ChisholmSD, CordellWH, RogersK, et al: Comparisonof a new saline-pressurizedcanister versus syringe irrigation for laceration cleaning in the emergencydepartment.Ann EmergMed 1992;21:1364-1367.
Copyright © by the American College of Emergency Physicians Reprint no. 47/1/56577 Address for reprints: Richard F Edlich, MD, PhD Departmentof PlasticSurgery Universityof VirginiaMedical Center Box 332 Charlottesville,Virginia22908 804-924-2085 Fax804-924-8431
ANNALS OF EMERGENCY MEDICINE
24:1
JULY 1994
Wound Irrigation Richard F Edlich,MD, PhD Department of PlasticSurgery University of Vir~nia MedicalCenter Charlottesville,Vir~nia
Wound Irrigation
John G Thacker, PhD Department of Mechanicaland Aerospace Enffmeering University of Virffmia MedicalCenter Charlottesville,Vir~nia
Twenty-five years have elapsed since our team of scientists demonstrated that wound irrigation delivered under low pressure was ineffective in preventing the development of wound infection. 1 Our observations were consistent with the results of earlier studies confirming the ineffectiveness of low-pressure wound irrigation. 2-s When we applied the principles of fluid dynamics to wound irrigation, we realized that the bacterial removal efficiency of irrigation would improve as the pressure at which the fluid was delivered to the wound was increased. 6 An irrigation assembly was constructed to deliver saline at varying pressures to a contaminated wound. The saline reservoir was pressurized by a CO 2 cartridge and adjusted to either 0.5 or 25 psi. This irrigation assembly delivered either a continuous or pulsatile irrigating stream of saline. Raising the delivery pressure of the irrigating stream markedly increased its bacterial removal efficiency and significantly reduced the incidence of bacterial infection. As expected, low-pressure irrigation had insignificant therapeutic merit. Furthermore, the results of our studies indicated that high-pressure irrigation must be continuous to have the mammal bacterial removal effect. The superiority of continuous flow over pulsatile flow in wound decontamination may be related to a time-dependent force, which is especially important in liquid systems. It was postulated that a strong force must be applied to bacteria for a protracted time to dislodge them from the wound. The continuous-flow jet appeared to provide the necessary duration of contact between the irrigating medium and the bacteria for effective wound decontamination. These high-pressure irrigation systems had been used primarily in operating rooms and were rarely used in emergency departments. They are designed primarily for
88
Seerelatedarticle, p 36. [Edlich BF,ThackerJG: Wound irrigation. Ann EmergMedJuly
1994;24:88-90.]
ANNALS OF EMER6ENCY MEDICINE 24:1 JULY 1994
EDITORIAL
cleansing large wounds, which are rarely encountered in emergency medicine practice. Consequently, we searched for and developed a practical alternate approach for use in the ED. Our new irrigating system used a commercially available syringe and needle to deliver the irrigant to the wound, r We derived analytically the maximum pressure experienced by a wound surface as the result of irrigating streams delivered by different needle syringe assemblies. The maximum pressure experienced by the tissue from an irrigating stream exiting from a needle was derived from the well-known Bernoulli's equation. A reservoir maintained under a measured static pressure was used to reproduce the conditions of the irrigant inside the syringe barrel. Exit irrigant velocities for each needle over a wide range of syringe barrel pressures were used to calculate the maximum pressures experienced by the wound surface. We then correlated these maximum static pressures to the conditions within the syringe barrel resulting from the physician pressing on the plunger. The average force exerted on the syringe plunger was determined with a pinch meter placed between the physician's thumb and plunger, which simulated syringe irrigation using o n e hand. With the physician's ring and index fingers grasping the concentric ring surrounding the syringe barrel end, the thumb pushed the plunger into the barrel. Two finger rings have been attached to the barrel of some disposable syringes to enhance the security of the physician's grasp of the syringe barrel. The pressure also was measured directly with the bulb syringe using a pressure transducer. The measured pressure within a 35-mL bulb syringe barrel attached to a 19-gauge needle was 19 psi, while the pressure within the bulb of the bulb syringe was only 5 psi. The pressures experienced by the wound surface from the fluid delivered by either the syringe assembly or bulb syringe were proportional to the pressures within these irrigation devices. The pressure experienced by a wound surface from fluid delivered from a 19-gauge needle and 35-mL syringe was 7 psi. In contrast, the pressure encountered by a surface irrigated by a bulb syringe was only 0.5 psi. The marked decrease in pressure from that encountered in the syringe barrel (19 psi) to the pressure experienced by the wound surface (7 psi) was caused by the frictional forces in the needle. For all treatments, the tip of either the needle or bulb syringe was placed as close as possible to the surface of the wound. The bacterial removal efficiency of the irrigating stream was proportional to the pressure experienced by the wound surface. High-pressure irrigation with a 35-mL
JULY 1994
24:1 ANNALS OF EMER6ENOY MEDICINE
syringe attached to a 19-gauge needle operated manually by one hand effectively decreased the level of bacterial contamination. The cleansing effect of the bulb syringe irrigation was negligible because the wound bacterial concentration was not significantly affected by this lowpressure irrigation system. High-pressure syringe irrigation markedly reduced the incidence of wound infection in contaminated wounds; bulb syringe irrigation did not alter the infection rate. Continuous high-pressure irrigation is also an effective means of removing soil infection-potentiating factors in dirt from the wound. 8 High-pressure irrigation removed 80% of the soil infection-potentiating factors from the wound. Changing the composition of the wound irrigant by adding chelating agents, flocculants and dispersants, or a nonionic surfactant did not significantly enhance the efficiency of removal of soil infection-potentiating factors in wounds. The benefits of high-pressure irrigation must be weighed against potential side effects. 9 Fears that pressure irrigation will disseminate bacteria into adjacent tissue area were unfounded. In our studies, high-pressure irrigation did not enhance the dissemination of bacteria into soft-tissue wounds. However, the irrigation fluid disseminated into the interstices of the wound, predominantly in a lateral direction. This lateral spread occurred within the loose areolar tissue, contributing to the development of postoperative edema. Concern that high pressure can damage tissue defenses was justified. High-pressure irrigation resulted in trauma to the wound, which made the wound more susceptible to infection. This finding serves to remind the emergency physician that this technique cannot be used indiscriminately and should be reserved for heavily contaminated wounds. Other investigators have expressed concerns about other potential complications encountered during highpressure syringe needle irrigation. Parkinson and Hirst 1° were concerned that an unguarded needle could be an invitation to inadvertent needle puncture of either an assistant or the patient. They advocated covering the needle with a malleable plastic sheath. We prefer a 19-gauge, blunt-ended plastic catheter rather than a metal needle. The occupational risk to the emergency physician of exposure to HIV or hepatitis virus by virtue of accidental splashing of the irrigant has been another potential complication. 1E Several techniques, such as cupping the gloved hand around the wound and irrigating through the space between the thumb and index finger, have been recommended to reduce splatter. 12 Recently, a cuplike device has been marketed to prevent splatter while allowing irri-
89
EDITORIAL
gation with appropriate pressures. Because the device trapped the irrigant in the wound area, bacteria may be reintroduced into the wound. A simpler solution to this problem is to position the tip of the blunt-ended plastic catheter perpendicular to and in contact with the wound surface. This intimate contact of the catheter with the wound diminishes splashing and ensures that the maximum wound irrigation force is used to decontaminate the wound. Emergency physicians who do not follow directions and continue to position the catheter i to 3 cm above the wound surface should realize that the pressure at which the fluid contacts the wound will be diminished. Inadvertent splashing will present a serious and unnecessary occupational hazard. Our research on the fluid dynamics of wound irrigation that has spanned more than two decades has been a catalyst for the design and development of a wide variety of other high-pressure wound irrigation systems for use in the ED. In this issue of Annals, Singer and colleagues question whether these different irrigation systems are indeed high-pressure irrigation systems. By placing a pressure transducer immediately proximal to the needle hub, they were able to measure and monitor the pressure changes in the irrigation systems. All methods of irrigation yielded relatively square pressure tracings, with no significant pressure decrement over the 250-mL boluses. Singer et al's pressure measurements within the 35-mL syringe attached to a 19-gauge needle (median peak pressure, 35 psi; median trough pressure, 17 psi) were greater than the pressure (19 psi) within the same pressure irrigation system reported earlier by our laboratory. 7 This discrepancy may be attributed to the different techniques of manual irrigation used in the two studies. In their study, subjects manually applied pressure to the syringe using two hands; our physician manipulated the syringe assembly with only one hand. Because the force exerted on the syringe using two hands should be considerably greater than that applied by one, the pressures encountered within the syringe should be proportional to the magnitude of forces applied to the syringe. In our study, a pressure of 19 psi within the syringe appeared to be necessary for effective wound decontamination. On this basis, we would select irrigation systems that encounter comparable pressures within the syringe or container. On the basis of the pressure recordings reported by Singer et al, only the 65-mL and 35-mL syringes attached to 19-gauge needles should be considered for high-pressure wound irrigation in the ED.
90
1. EdlichRF, CusterJ, Madden J, et al: Studies in the managementof the contaminatedwound. III. Assessmentof the effectiveness of irrigation with antiseptic agents. AMJ Surg1969;118:3130. 2. FalconerB, Liljedahl SO, OlovsonT: On the effect of treatment of traumatic wounds with soap solution: An experimental study. Acta ChirScand1952;103:222-235. 3. Casten DF, Nach RJ, SpinziaJ: An experimentaland clinical study of the effectivenessof antibiotic wound irrigation in preventing infection. SurgGynecolObstet1964;118:783-787. 4. GingrassRP, CloseAS, Ellison EH:The effect of various topical and parenteralagents on the prevention of infection in experimentalwounds. J Trauma1964;4:763-783, 5. HopsonWB Jr, Britt LG, ShermanRT, et al: The use of topical antibiotics in the prevention of experimentalwound infection. J SurgRes 1968;8:261-266. 6. Madden J, EdlichRF, SchauerhamerR, et al: Applications of principles of fluid dynamics to surgical wound irrigation. CurrTopicsSurgRes 1971;3:85-92. 7. StevensonTR, ThackerJG, RodeheaverGT, et al: Cleansingthe traumatic wound by highpressure syringe irrigation. JACEP1976;5:17-21. 8. RodeheaverGT, Pettry D, ThackerJG, et al: Wound cleansingby high pressure irrigation. Surg GynecolObstet1975;141:357-362. 9. Wheeler CB, RodeheaverGT, ThackerJG, et al: Side-effects of high pressure irrigation. Surg GynecolObstet1976;143:775-778. 10. ParkinsonRW, Hirst P: A simple needle guard for low-volume, high-pressure irrigation, BrJ Accid Surg1990;21:128. 11. ChernofskyMA, Murphy RXJr, JenningsJF: A harrier technique for pulsed irrigation of cavitarywounds. PlastReconstrSurg1993;91:365-366. 12. ChisholmSD, CordellWH, RogersK, et al: Comparisonof a new saline-pressurizedcanister versus syringe irrigation for laceration cleaning in the emergencydepartment.Ann EmergMed 1992;21:1364-1367.
Copyright © by the American College of Emergency Physicians Reprint no. 47/1/56577 Address for reprints: Richard F Edlich, MD, PhD Departmentof PlasticSurgery Universityof VirginiaMedical Center Box 332 Charlottesville,Virginia22908 804-924-2085 Fax804-924-8431
ANNALS OF EMERGENCY MEDICINE
24:1
JULY 1994