The evolution of wound care has seen much technological advancement over many decades. Most recently, negative-pressure therapy, by which a vacuum pressure is applied through a wound bed, has dramatically improved the surgical outcomes of complex wounds. Although initial studies focused on wounds to the abdomen, torso, and extremities, more publications are appearing that demonstrate the efficacy of negative-pressure wound therapy in the head and neck. This article reviews the history and evolution of negative-pressure therapy, highlights the current opinions on its mechanism of action, and summarizes its use in complex head and neck wounds.
Key points
Negative-pressure wound therapy
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Is a safe, efficacious, and cost-effective treatment strategy in the management of complex head and neck wounds.
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Reduces wound infections, shortens hospital stays, and simplifies wound reconstruction strategies.
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Should be included in the wound management strategies of otolaryngologists and facial plastic surgeons.
Introduction
The treatment of complex head and neck wounds has presented unique challenges throughout the evolution of modern wound care. In addition to the array of difficulties that large wounds present in general, such as tissue loss, poor vascularity, and chronic infection, wounds to the head and neck region are particularly challenging because of their highly visible location and relative paucity of available adjacent tissue for simple reconstruction. The traditional methods used to reconstruct large or chronic wounds in other regions of the body, namely, skin grafting, tissue expansion, and free flaps, may be suboptimal in the head and neck. Specifically, skin grafts and free tissue transfers often result in poor color or thickness matching to adjacent structures, whereas tissue expansion is associated with significant morbidity during the lengthy expansion process. In addition, the increasing complexity of surgical resections in head and neck cancer and the improvements in radiation treatment have resulted in an increased number and variety of challenging facial reconstructions. For these reasons, recent focus has turned to the use of vacuum-assisted closure, a technique that has been widely successful in the treatment of wounds in other regions of the body, to address complex head and neck wounds.
The Advent of Suction Drainage
The evolution of negative-pressure therapy began early this century with the advent of suction drainage. In 1934, Chaffin described the use of a suction drainage device that he developed to facilitate drainage in areas where gravity was inefficient, such as the abdomen, pelvis, and neck. Chaffin’s device was simply a perforated suction catheter attached to a collection canister, which was in turn connected to a vacuum generated by a tank of running water. By inserting this catheter into a healing wound bed, he immediately noted improved wound healing and patient recovery. Silvis and colleagues went on to describe the use of continuous negative suction following mandibular resection and radical neck dissections, demonstrating prevention of subcutaneous serum collections and increased collateral blood flow resulting in fewer postoperative infections and fewer instances of skin necrosis. Moloney expanded on these observations by applying suction drainage devices after salivary gland resections and thyroidectomies. In 1959, Breslau and colleagues introduced the first method of providing portable continuous suction. Initial studies of 50 cases using this technique reported a stronger and more rapidly forming scar, shorter hospital stays, and a very rare occurrence of necrosis, infection, or dehiscence. In 1962, Von Leden and Kaplan went on to describe the use of the portable HemoVac system (Snyder Manufacturing Corp). The HemoVac system was then used by McLean in his landmark study comparing head and neck postoperative wounds with and without suction. This study demonstrated significant decreases in morbidity associated with suction drainage; patients developed fewer salivary fistulas, fewer soft tissue infections, and began oral feedings at earlier dates. Histologically, wounds in the suction-drainage group were less edematous, better approximated, and less frequently necrotic.
The underlying principles of closed suction that led to the improvements in overall wound healing were well articulated by McLean and colleagues, namely, the removal of devitalized and necrotic tissue, reduction of secondary edema, minimization of dead spaces, close apposition of wound edges, and stimulation of intracellular histamine. Thus, the use of suction drainage became the standard of care for the next 30 years, with few changes in its application. During this time, the observations by Winter on moist wound healing principles led to the development of alginates, hydrogels, debriding agents, and antimicrobial agents, with modest effects on overall wound healing.
Development of Negative-Pressure Wound Therapy
It was not until the 1990s that Argenta and Morykwas expanded on the principles of suction drainage by introducing negative-pressure wound therapy. This method uses an interface material, typically a hydrophobic collapsible foam, to distribute the force of a vacuum throughout the wound rather than simply placing a suction catheter drain within the closed wound bed. The term negative pressure is a misnomer because it is a relative pressure to the atmospheric pressure and not a true negative value; the importance of this pressure difference is underscored by the fact that wounds do not heal more efficiently at lower atmospheric pressures, such as at high elevations. The device consists of a semiocclusive dressing with a connection for suction tubing, which is in turn connected to a portable vacuum source with a collection canister. The semiocclusive dressing is placed on top of the interface material that lies within the wound bed; when the vacuum is started, the dressing holds a seal, drawing the wound edges closer together while facilitating fluid removal through the drainage tube.
Mechanism of Action of Negative-Pressure Therapy
The precise mechanism of action whereby negative-pressure wound therapy facilitates improved wound healing has been the subject of many studies. Orgill and Bayer reviewed the most recent peer-reviewed literature investigating negative-pressure therapy and categorized these mechanisms into 5 major physiologic categories: fluid removal, blood flow changes, microdeformation, macrodeformation, and maintenance of wound hemostasis. Fluid removal has been known to improve wound healing since the introduction of suction drainage and is now thought to act by improving nutrient transport, removing toxins, reducing bacterial load, and modulating local blood flow changes. Blood flow changes during the application of negative pressure have been extensively studied. During the application of negative pressure, blood flow decreases at the wound edge but then increases on its release. The intermittent application of negative pressure is thought to provide an overall increased blood flow to wound edges, whereas the transient hypoxia induced by the vacuum is thought to stimulate vasculogenesis and increase granulation tissue formation. The observations that cell proliferation and organization of cellular structural elements are related to cell shape led Saxena and colleagues to propose microdeformation as the mechanism by which dramatic granulation tissue forms in wounds under negative pressure despite minimal fluid removal. Their group demonstrated increased microdeformation, elongation of wound surface, increased neuropeptide levels, and more ordered blood vessel morphology in wounds treated with negative pressure compared with foam alone. Macrodeformation is the reduction in wound size when negative pressure is applied and is a function of both the compressibility of the interface material and the deformability of the surrounding skin. This reduction in wound size can allow the reconstructive surgeon to select a less complex reconstruction strategy, such as a local advancement flap in place of a free tissue transfer or primary closure in place of skin grafting. Finally, the application of the semiocclusive material decreases heat loss, minimizes evaporation, and reduces desiccation. No clinical studies have been published on the efficacy of macrodeformation or hemostasis as they relate to negative-pressure therapy.
The most popular device for applying negative-pressure therapy has been the vacuum-assisted closure system (VAC; Kinetic Concepts, Inc, San Antonio, Texas). This device has been successfully used in the management of complex wounds in general surgery, orthopedic surgery, gynecologic surgery, and plastic and reconstructive surgery. A meta-analysis of negative-pressure therapy trials versus standard wound-care therapy was recently published by Suissa and colleagues and concluded that negative-pressure therapy leads to significant reduction in wound size and time to healing. Despite these studies, there exists a paucity of literature comparing standard wound-care therapy to vacuum-assisted therapy in the region of the head and the neck. This article reviews the literature on vacuum-assisted closure of head and neck wounds and discusses its potential benefits and pitfalls.
Introduction
The treatment of complex head and neck wounds has presented unique challenges throughout the evolution of modern wound care. In addition to the array of difficulties that large wounds present in general, such as tissue loss, poor vascularity, and chronic infection, wounds to the head and neck region are particularly challenging because of their highly visible location and relative paucity of available adjacent tissue for simple reconstruction. The traditional methods used to reconstruct large or chronic wounds in other regions of the body, namely, skin grafting, tissue expansion, and free flaps, may be suboptimal in the head and neck. Specifically, skin grafts and free tissue transfers often result in poor color or thickness matching to adjacent structures, whereas tissue expansion is associated with significant morbidity during the lengthy expansion process. In addition, the increasing complexity of surgical resections in head and neck cancer and the improvements in radiation treatment have resulted in an increased number and variety of challenging facial reconstructions. For these reasons, recent focus has turned to the use of vacuum-assisted closure, a technique that has been widely successful in the treatment of wounds in other regions of the body, to address complex head and neck wounds.
The Advent of Suction Drainage
The evolution of negative-pressure therapy began early this century with the advent of suction drainage. In 1934, Chaffin described the use of a suction drainage device that he developed to facilitate drainage in areas where gravity was inefficient, such as the abdomen, pelvis, and neck. Chaffin’s device was simply a perforated suction catheter attached to a collection canister, which was in turn connected to a vacuum generated by a tank of running water. By inserting this catheter into a healing wound bed, he immediately noted improved wound healing and patient recovery. Silvis and colleagues went on to describe the use of continuous negative suction following mandibular resection and radical neck dissections, demonstrating prevention of subcutaneous serum collections and increased collateral blood flow resulting in fewer postoperative infections and fewer instances of skin necrosis. Moloney expanded on these observations by applying suction drainage devices after salivary gland resections and thyroidectomies. In 1959, Breslau and colleagues introduced the first method of providing portable continuous suction. Initial studies of 50 cases using this technique reported a stronger and more rapidly forming scar, shorter hospital stays, and a very rare occurrence of necrosis, infection, or dehiscence. In 1962, Von Leden and Kaplan went on to describe the use of the portable HemoVac system (Snyder Manufacturing Corp). The HemoVac system was then used by McLean in his landmark study comparing head and neck postoperative wounds with and without suction. This study demonstrated significant decreases in morbidity associated with suction drainage; patients developed fewer salivary fistulas, fewer soft tissue infections, and began oral feedings at earlier dates. Histologically, wounds in the suction-drainage group were less edematous, better approximated, and less frequently necrotic.
The underlying principles of closed suction that led to the improvements in overall wound healing were well articulated by McLean and colleagues, namely, the removal of devitalized and necrotic tissue, reduction of secondary edema, minimization of dead spaces, close apposition of wound edges, and stimulation of intracellular histamine. Thus, the use of suction drainage became the standard of care for the next 30 years, with few changes in its application. During this time, the observations by Winter on moist wound healing principles led to the development of alginates, hydrogels, debriding agents, and antimicrobial agents, with modest effects on overall wound healing.
Development of Negative-Pressure Wound Therapy
It was not until the 1990s that Argenta and Morykwas expanded on the principles of suction drainage by introducing negative-pressure wound therapy. This method uses an interface material, typically a hydrophobic collapsible foam, to distribute the force of a vacuum throughout the wound rather than simply placing a suction catheter drain within the closed wound bed. The term negative pressure is a misnomer because it is a relative pressure to the atmospheric pressure and not a true negative value; the importance of this pressure difference is underscored by the fact that wounds do not heal more efficiently at lower atmospheric pressures, such as at high elevations. The device consists of a semiocclusive dressing with a connection for suction tubing, which is in turn connected to a portable vacuum source with a collection canister. The semiocclusive dressing is placed on top of the interface material that lies within the wound bed; when the vacuum is started, the dressing holds a seal, drawing the wound edges closer together while facilitating fluid removal through the drainage tube.
Mechanism of Action of Negative-Pressure Therapy
The precise mechanism of action whereby negative-pressure wound therapy facilitates improved wound healing has been the subject of many studies. Orgill and Bayer reviewed the most recent peer-reviewed literature investigating negative-pressure therapy and categorized these mechanisms into 5 major physiologic categories: fluid removal, blood flow changes, microdeformation, macrodeformation, and maintenance of wound hemostasis. Fluid removal has been known to improve wound healing since the introduction of suction drainage and is now thought to act by improving nutrient transport, removing toxins, reducing bacterial load, and modulating local blood flow changes. Blood flow changes during the application of negative pressure have been extensively studied. During the application of negative pressure, blood flow decreases at the wound edge but then increases on its release. The intermittent application of negative pressure is thought to provide an overall increased blood flow to wound edges, whereas the transient hypoxia induced by the vacuum is thought to stimulate vasculogenesis and increase granulation tissue formation. The observations that cell proliferation and organization of cellular structural elements are related to cell shape led Saxena and colleagues to propose microdeformation as the mechanism by which dramatic granulation tissue forms in wounds under negative pressure despite minimal fluid removal. Their group demonstrated increased microdeformation, elongation of wound surface, increased neuropeptide levels, and more ordered blood vessel morphology in wounds treated with negative pressure compared with foam alone. Macrodeformation is the reduction in wound size when negative pressure is applied and is a function of both the compressibility of the interface material and the deformability of the surrounding skin. This reduction in wound size can allow the reconstructive surgeon to select a less complex reconstruction strategy, such as a local advancement flap in place of a free tissue transfer or primary closure in place of skin grafting. Finally, the application of the semiocclusive material decreases heat loss, minimizes evaporation, and reduces desiccation. No clinical studies have been published on the efficacy of macrodeformation or hemostasis as they relate to negative-pressure therapy.
The most popular device for applying negative-pressure therapy has been the vacuum-assisted closure system (VAC; Kinetic Concepts, Inc, San Antonio, Texas). This device has been successfully used in the management of complex wounds in general surgery, orthopedic surgery, gynecologic surgery, and plastic and reconstructive surgery. A meta-analysis of negative-pressure therapy trials versus standard wound-care therapy was recently published by Suissa and colleagues and concluded that negative-pressure therapy leads to significant reduction in wound size and time to healing. Despite these studies, there exists a paucity of literature comparing standard wound-care therapy to vacuum-assisted therapy in the region of the head and the neck. This article reviews the literature on vacuum-assisted closure of head and neck wounds and discusses its potential benefits and pitfalls.
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