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Surgical drains
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Chapter
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Surgical drains L.J. Owen
Surgical drains can be valuable adjuncts to patient management, both in superficial locations and within body cavities; however, their use is not without risks or complications. Used correctly, surgical drains promote wound healing, reduce infection rates, and decrease patient morbidity, but used inappropriately these potential benefits can be reversed. In particular, drains should not be used as an alternative to appropriate wound debridement, lavage and suction, and meticulous wound closure. Surgeons should consider carefully the pros and cons of drain use before placement. A thorough understanding of the types of drain available, their advantages and disadvantages and correct method of placement, will help ensure that they are used in an optimal fashion.
INDICATIONS Surgical drains perform three main functions:
• Obliteration of dead space • Removal of pre-existing fluid or air from a wound/body cavity • Preventing anticipated fluid or air accumulation within a wound/body cavity. Whilst the first two therapeutic functions are widely accepted, the latter prophylactic use of surgical drains can be a controversial area. The use of a surgical drain to obliterate dead space is most commonly employed following en-bloc resection of neoplastic masses or chronic, contaminated and infected wounds. The definitive loss of tissue in these situations means that closure of individual wound layers is impractical and placement of a wound drain functions to appose tissue layers and promote healing. The use of surgical drains to remove pre-existing fluid or air is most commonly from a fluid-filled peripheral swelling, e.g., salivary mucocele or abscess, or from a body cavity. The removal of fluid from a surgical site is desirable due to the negative effects of the fluid on the host’s resistance to infection.1 This occurs via several mechanisms (Box 11-1). Drains are placed routinely during thoracic surgical procedures to evacuate postoperative pneumothorax and to remove either pre-existing or anticipated fluid, which may cause respiratory compromise. In the abdomen, drains are used predominantly for the purposes of removing septic exudate, e.g., in cases of septic peritonitis. Removal © 2014 Elsevier Ltd DOI: 10.1016/B978-0-7020-4336-9.00011-1
of transudates, modified transudates or blood is rarely of benefit to the patient. The most common indication for the prophylactic placement of a surgical drain is in combination with reconstructive surgery and the use of cutaneous and myocutaneous flaps. There is evidence within the veterinary literature that seroma formation is a common sequel to these procedures and that drain placement reduces the prevalence of this and subsequently of wound dehiscence and flap failure.2–4 Whether or not prophylactic drain placement is beneficial following other surgical procedures, however, remains controversial. In human medicine, Cochrane Systematic Reviews investigating the prophylactic use of surgical drains in orthopedic surgery, thyroid surgery, and incisional hernia repairs have failed to show any benefits in drain placement, but have shown some clear disadvantages, e.g., prolongation of hospital stay.5–7 In veterinary medicine, there is a distinct lack of published data on this subject, eliminating the use of an evidence based approach; thus surgeons are reliant upon anecdotal evidence and their own experience to determine whether a drain should be placed in any individual case. Experimental studies have documented prolonged tissue healing and reduced blood supply to cutaneous wounds in the cat compared with the dog, which may predispose to seroma formation in cats; however, clinical studies to support this have not been performed.8–11 In addition, cat owners may be poorly compliant at restricting exercise, allowing behavior such as jumping, which may contribute to problems with wound healing and seroma formation.
ALTERNATIVES TO SURGICAL DRAINS In some patients or for certain surgical procedures, it may be more appropriate to consider alternatives to the use of a surgical drain, such as incomplete wound closure, omental pedicle flaps or bandaging.
Incomplete wound closure The most distal portion of a surgical wound can be left open to provide drainage, and is a simple, cheap and usually effective method of preventing fluid accumulation within a surgical site postoperatively.
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Figure 11-1 Omentum tunneled from a paracostal abdominal exit point for placement into a chronic axillary collar wound. Small arrow, paracostal incision; arrowhead, axillary wound with omentum in place.
Box 11-1 The negative effects of fluid accumulation at surgical sites • Reduced ability to opsonize bacteria for phagocytosis • Reduced access of phagocytes into the wound • Ability of the fluid to act as a substrate to promote bacterial growth • Reduced vascular supply to tissues • Reduced penetration of systemically administered antibacterial agents into the surgical site
Figure 11-2 Penrose drains: 1 inch and 0.25 inch.
poorly tolerant of dressings and their presence may reduce feeding and normal behavior postoperatively.
TYPES OF DRAINS Drains are generally categorized according to function, i.e., whether they act as a passive route for passage of fluids or if they have a more active role in drainage.
Passive drains This technique can also be applicable to body cavities, particularly in the treatment of septic peritonitis by open peritoneal drainage. The main disadvantages of this technique are the increased risk of wound infection, reduced wound healing, and requirement for bandaging to collect the fluid.
Passive drains provide an exit point for fluid from a surgical site postoperatively, but do not actively reduce dead space within a wound and do not provide optimal drainage of air. Several types of passive drain exist, including Penrose drains, tube drains, sump drains, and corrugated drains; however, only the former are commonly in use in companion animal medicine and thus the others will not be considered further here.
Omentum
Penrose drains
Omentum can be used as an autogenous wound drain (Fig. 11-1). Its beneficial properties include promotion of angiogenesis, improved immune function, and tissue fluid drainage and it has been used successfully to promote healing of a variety of wound types in cats, particularly axillary collar wounds (see Chapter 18) and indolent pocket wounds, which are both challenging to treat by other methods.12,13 The use of omentum is, however, limited by its availability and the location of the wound: complications such as necrosis of the omental fat and incisional herniation through the omental exit point from the abdominal cavity have been reported.12 For information on how to create an omental flap see Chapter 19.
Penrose drains are composed of soft latex and are a flattened tube of variable diameter (0.25–1 inch) (Fig. 11-2). They are readily available, easy to use and cheap, making them a popular choice. This type of drain relies on gravitational forces, capillary action and overflow for wound drainage and therefore is limited to use in locations where these forces can be utilized. Penrose drains placed on the head or dorsum, or exiting from the lateral or dorsal aspects of a surgical site are unlikely to function and will instead contribute to complications of wound healing. The gravitational and capillary action of fluid drainage is related to the surface area of the drain and thus fenestration of these drains is contraindicated. In addition to reducing the efficiency of the drain, fenestration will also predispose to breakage of the drain during removal. Penrose drains are indicated for use in superficial wounds where there is pre-existing or anticipated fluid production and should have a single ventral exit point. Allowing the drain to have a second exit point proximally is not recommended.15 This serves only to increase the risk of wound infection and air transmission through the wound, without conferring any advantages to the patient. The main use of the
Pressure bandage The use of a bandage to maintain apposition of tissue planes is a suitable alternative to a surgical drain in some locations, e.g., distal limb.14 However, there are many anatomical locations where application of a bandage is difficult or where it may compromise normal function, e.g., cervical and thoracic regions. In addition, cats are often
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Box 11-2 Penrose drain placement The drain insertion and surgical site is clipped and aseptically prepared according to standard techniques. The distal portion of the drain is placed to exit through a stab incision in the most dependent area of the surgical site (Fig. 11-3A). This stab incision must always be separate from the main surgical wound and the size of the drain exit hole should be minimized to reduce the risk of herniation of fat/other organs, although it should not restrict fluid flow. The proximal aspect of the drain is secured to the skin at the dorsal limit of the wound with a single non-absorbable external skin suture (Fig. 11-3B). The ends of this suture are commonly left longer than the standard skin sutures to allow the drain suture to be identified at time of drain removal. The distal portion of the drain is cut to leave approximately 2–3 cm of drain visible from the exit site and the drain is secured at this site with a second single nonabsorbable skin suture, to prevent retraction of the drain into the subcutaneous space (Fig. 11-3C). The total length of the drain is recorded at time of insertion so that this can be verified at time of drain removal. The skin surrounding the drain is protected from fluid scalding with petroleum jelly or similar. A sterile and absorbent bandage is applied over the drain wherever possible to reduce contamination postoperatively.
Penrose drain removal To remove the drain, the two non-absorbable sutures (proximal and distal) are cut and the drain is gently pulled through its original exit site. The exit site is left to close by secondary intention healing. Consider culture of the drain tubing after removal if there are any concerns about infection.
A
B
C
Figure 11-3 Penrose drain placement. (A) A stab incision is made away from the main suture line of a surgical wound and a Penrose drain is drawn through this incision into the wound. (B) The proximal part of the Penrose drain is secured to the skin by a simple interrupted suture. (C) Following closure of the main surgical wound, only a small portion of the distal Penrose drain is visible exiting from a single point in the dependent part of the surgical site and secured by a simple interrupted suture.
double exit technique has traditionally been to prevent subcutaneous emphysema developing in areas of high motion, e.g., the axilla or inguinal region, where air may be sucked into the wound by a single exit point; however, this is not usually considered to be a significant clinical problem.16 After placement, where location permits, the drain should be covered by a sterile absorbent contact layer and bandage. This is for collection of the fluid produced, and to reduce the risk of introduction of hospital or environmentally acquired pathogens. The dressing should be changed according to the rate of fluid production from the wound. In locations where bandaging is not possible or would likely result in additional complications, petroleum jelly or similar is applied liberally to the clipped area ventral to the drain to prevent fluid from scalding the skin and to allow easy cleaning of the area. The problems of feline intolerance to dressings and requirements for sedation for dressing changes, thus increasing morbidity and cost, should be taken into consideration when using these drains. The technique of drain placement and removal is described in Box 11-2.
Tube drain A simple plastic or rubber tube drain can also be used to provide passive drainage. The advantage over a Penrose drain is that the tube does not collapse and thus drainage of fluid may be more rapid and air can more readily be removed from a wound (Fig. 11-4); however, they are likely to cause increased patient discomfort due to their rigidity and they may become occluded during use. Tube drains may also be placed to allow instillation of local anesthetic agents into a surgical site postoperatively, rather than to provide drainage from the wound. The same drain should not be used for both purposes due to the risk of introducing pathogenic organisms.
Figure 11-4 Placement of a passive tube drain to allow exit of air following a dorsal rhinotomy in a cat. (© Adrian Wallace.)
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Active drains Active drainage is created by application of a vacuum to a wound drain. These drains are generally easier to manage in comparison to passive drains and have reduced risk of ascending infection.
Closed suction drains This type of drain is commonly used in superficial surgical sites, to obliterate dead space, to remove pre-existing fluid and air, or to prevent formation of fluid within the site postoperatively. Several commercial suction drains are available, which consist of a rigid, non-collapsible tube drain attached to a collection chamber (compressible or pre-applied vacuum); however, their size and weight need to be considered before their application to cats. The smaller, concertina/grenade type drains are appropriate in most cases and are often very effective (e.g., Mini Red-O-Pack drains or Jackson Pratt drains) (Figs 11-5 and 11-6). As well as being a suitable size, in experimental studies these drains have been shown to operate at a lower
pressure and in a more consistent manner compared to rigid drains; thus minimizing the effect of the drain itself on fluid production within the wound.17 Application of suction to these drains results in a negative pressure of approximately −80 to −120 mmHg within the wound, which is sufficient to obliterate dead space without excessively traumatizing the soft tissues.1,17,18 As the reservoir becomes filled, the negative pressure generated reduces and the drain becomes less efficient; although the Jackson Pratt and Mini Red-O-Pack drains have been shown to maintain suction at a lower level throughout filling of the reservoir.17 Homemade closed suction drains can be particularly useful in cats due to their reduced weight, size, and cost. Two main variations are reported. For both types, the portion of the drain that is to be placed in the wound is made from a 19G butterfly catheter, which has had multiple fenestrations made into the tubing. These fenestrations should not exceed 30% of the tube diameter, to reduce the risk of the tube kinking or breakage of the tubing on removal.16 The needle from the butterfly catheter can then be placed into a standard blood collection vacutainer (ideally made of plastic rather than glass) to provide suction (Fig. 11-7). Alternatively, the butterfly catheter tubing can be connected to a syringe. The syringe plunger is withdrawn to apply suction and a hypodermic needle is placed across the syringe case to maintain this suction. Both drains are then secured to the trunk with additional sutures or a mesh stockinette. These drains are usually only suitable for use in wounds where minimal fluid production is expected, due to the limited capacity of the collection device. Continuous suction devices are considered optimal for wound care, but more simple constructions utilizing intermittent suction may have some suitable applications. Closed suction drains have several advantages over passive drains (Box 11-3). The disadvantages are increased cost (which may be offset
Box 11-3 Advantages of closed suction drains
Figure 11-5 Mini Red-O-Pack closed suction drain. (With permission from Vygon Vet.)
Figure 11-6 Reconstruction of a large soft tissue deficit, following en-bloc resection of a fibrosarcoma from the left flank, using a caudal superficial epigastric skin flap. A mini Red-O-Pack closed suction drain has been placed, in addition to a tube drain for instillation of local anesthetic agents. (With permission from Vygon Vet.)
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• • • • • • •
No bandaging required Reduced risk of nosocomial infections Work independent of gravity Fluid production can readily be quantified Fluid can easily be sampled for repeat cytological examination Fluid and air are more efficiently removed Reduced risk of tube occlusion when continuous suction is used.
Figure 11-7 Application of a homemade butterfly catheter closed suction drain, following an omocervical axial pattern flap in a cat.
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Box 11-4 Closed suction drain placement The drain insertion and surgical site is clipped and aseptically prepared according to standard techniques. The drain tubing is placed within the wound so that all fenestrations lie subcutaneously, thus allowing an airtight seal to form. An exit point for this tubing is made away from the main surgical wound via a stab incision or by using the needle attached to the tubing that is provided in some commercial kits. For closed suction drains, the exit point of the drain does not need to be at a dependent point and therefore can be placed so as to make drain management easier and its position more comfortable for the patient. At the exit point, the drain is secured to the skin using a Roman sandal suture (Fig. 11-8). A sterile adhesive dressing is applied around the exit point of the drain to keep this area as clean as possible. The drain tubing is connected to the collection chamber, which is activated immediately if an airtight seal has been achieved using wound closure alone, or after 6–8 hours once a fibrin seal has formed. The collection chamber is secured to the patient using further sutures or a stockinette dressing or both.
A
Closed suction drain removal Removal of the drain is accomplished by cutting all of the securing sutures, followed by withdrawal of the tubing from the wound. The exit site is left to close by second intention healing. Consider culture of the drain tubing after removal if there are any concerns about infection.
B Figure 11-9 (A) 14G wire-guided thoracic drain. (B) Close up of the tip showing the fenestrations (with permission from MILA International, Inc. www.milaint.com).
Figure 11-8. A Roman sandal friction suture is used to secure drain tubing to the skin.
by the cost of the dressings and the sedation required for management of a passive drain) and potential occlusion of the drain or reflux of fluid back into the wound. The technique for insertion of active drains is described in Box 11-4.
THORACIC DRAINS Three main types of thoracic drain are available for use in small animals: trocar drains, non-trocar drains, and Seldinger-type drains. All three are suitable for use in cats; however, the Seldinger-type is increasing in popularity for use in this species due to the small diameter of the drain, which is associated with a significant reduction in patient discomfort and morbidity. Trocar and non-trocar drains are available in a range of sizes; 10–16 Fr are most commonly used in cats.18 Traditionally, the size of drain selected should approximate the diameter of the mainstem
bronchus;19 however, smaller lumen drains reduce discomfort and thus may be preferable in many situations. Both of these drain types require sedation, or more commonly general anesthesia, for placement in a cat, and can be placed under direct observation during surgery, or as an extra-thoracic technique. Placement of these drains requires considerable force to pass them through the intercostal musculature and a particular concern when dealing with small patients such as cats, with high thoracic wall compliance, is the risk of iatrogenic damage to the heart/lungs/vessels in the thorax during placement. The Seldinger-type thoracic drains are relatively new in veterinary medicine and are more expensive, but have some significant advantages over the wide-bore drains. The most commonly used drain is 14G in size (Fig. 11-9) and the atraumatic technique with which it is placed means that local anesthesia or mild sedation is often sufficient, avoiding the need for, risks associated with, and cost of general anesthesia. A potential disadvantage often cited is the risk of occlusion of the narrow bore tube with thicker effusions, e.g., pyothorax; however, in a recent veterinary study this was not found to be a significant problem.20 The small size of these drains results in a significant reduction in postoperative morbidity, particularly in cats due to their relative smaller chest size and therefore the author considers these thoracic drains to be optimal for use in the majority of feline patients. The technique of placement of thoracic drains is covered in Chapter 41.
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Diagnostics, Equipment and Implants confers no additional advantage, but increases the risk of infection due to increased drain handling. Dressing changes should be performed as aseptically as possible and the drain exit site should be examined at least once daily for the presence of erythema, discharge or swelling.
WHEN TO REMOVE
Figure 11-10 Jackson Pratt abdominal drain placed for postoperative management of septic peritonitis in a cat.
ABDOMINAL DRAINS The Jackson Pratt closed suction drain (Fig. 11-10) is the most common type used for drainage of the abdominal cavity. This is a wide, flat silicone drain, with multiple fenestrations, which reduces the occurrence of drain occlusion during use. The flat portion of the drain merges into tubing, which exits the body wall and attaches to a grenade type collection chamber. Usually, the drain is positioned to lie along the ventral midline of the abdominal cavity, where the majority of fluid will collect due to gravitational forces. Drain use within the abdominal cavity is restricted to situations where ongoing fluid production is expected, e.g., in cases of septic peritonitis where the cause remains unresolved. The advantage of placing a drain is that it allows monitoring of the nature of the fluid produced within the abdomen and repeat cytological analysis to assess for improvement or deterioration of the patient’s condition. The main disadvantages are occlusion of the drain by omentum and fibrin, the increased risk of wound dehiscence if the drain is placed too close to an intestinal or other organ incision, and the additional expense of these drains. More details on indications and placement of this type of drain will be covered in Chapter 26.
POSTOPERATIVE CARE An Elizabethan collar is mandatory for all patients with a surgical drain in place, to prevent premature removal or damage to the drain. In some cats and depending upon the location of the drain, it may be possible to use a soft collar to allow them to feed more easily and to avoid problems with postoperative anorexia. If a rigid collar is deemed necessary, it may need to be removed under close observation at feeding times. Drains are likely to add to patient discomfort in the postoperative period and appropriate analgesia should be supplied while they are in place. Nosocomial infections are a significant risk of drain placement and can lead to multi-resistant wound infections and costly complications. Gloves should ALWAYS be worn when handling the drain or the surgical site. In addition, closed suction drains should only be emptied once they become full, or if suction is lost. More frequent emptying
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All surgical drains will act as foreign material within the surgical site and as such will result in soft tissue irritation and inflammation. This inflammatory response will elicit some fluid production independent of the surgical disease and thus fluid production from the drain is rarely expected to reduce to zero after placement. As a general guide, approximately 2–4 mL/kg/24 hours is deemed to be acceptable and likely to be solely due to drain presence; thus when fluid production reduces to this level, the drain can be removed. Alternatively, where this level is not reached, but the quantity of fluid drained remains static over two to three days, the drain should also be removed. In order to use these guidelines, it is important that fluid production is accurately quantified when drains are emptied, and recorded so that the 24 hour rate of fluid production can be calculated. Because of the difficulty of quantifying fluid production from Penrose drains, these drains are usually removed when fluid production has become serosanguinous/transudate in nature and the amount of fluid is subjectively considered to be decreasing or is unchanged over a number of days. This commonly occurs by day 3 to 5 postoperatively. Delay in removal of the drain beyond this point is generally not recommended, as the advantages of continued drain placement reduce, and the risks of infection and costs of bandaging and hospitalization increase.
COMPLICATIONS Infection Removal of fluid from a surgical site is known to be beneficial in reducing infection, because the presence of fluid interferes with opsonization of bacteria, phagocytosis and antibacterial agent penetration. In contrast however, the presence of the drain within the wound may decrease the host’s innate resistance to infection and handling of the drain in the postoperative period, often by multiple nursing personnel, carries an inherent risk of introducing nosocomial organisms into the wound. These latter infections may involve organisms with increased pathogenicity compared to original wound contaminants and thus infection with these organisms can greatly increase morbidity or result in patient mortality in the worst case scenario. This means that when drains are used optimally and are active in removing fluid from a wound/resolving dead space, they are likely to be advantageous in fighting infection. If drains are, however, used in a prophylactic setting only, or are poorly managed postoperatively, the overall effect may be more detrimental than beneficial to the individual.
Wound dehiscence Drains placed to exit through the main wound incision result in increased wound dehiscence and therefore they are always placed to exit at a separate and distant site. Placement of drains within the abdomen adjacent to sites of intestinal anastomosis or incisions into other organs has been shown to increase the risk of wound dehiscence in human beings and the same is likely to be true in animals.
Surgical drains
Occlusion This is a problem of tube drains, which are prone to becoming occluded during use. Occlusion generally occurs by one of three mechanisms: the fluid exiting the drain is too viscous for the size of the drain tubing; fluid production has significantly reduced and thus consolidation of material is allowed to occur within the tubing; or the drain holes within the wound/body cavity have become occluded by fibrous tissue or omentum. Once a drain has become occluded, the clinician must decide upon the next course of action. If fluid production has significantly reduced, removal of the drain would be the most appropriate action. If, however, the function of the drain is still required, the clinician can attempt to aspirate the clot from the tube or a new drain may need to be placed.
Premature drain removal Cats are fastidious groomers by nature and will show a keen interest or dislike to foreign objects and sutures attached to their body. If the drain is accessible to them, it is likely to be removed by the patient and thus an Elizabethan collar is necessary in all cases to prevent this
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from occurring. Premature drain removal may result in unwanted fluid build-up within the surgical site or the need for repeat placement of the drain under a second anesthetic or sedation.
Drain retention or breakage Retraction of the drain back into the wound bed or breakage of the drain during removal can occur. Recording the length of drain initially placed within the wound, using only radio-opaque drains and adequately securing drains at the exit site should limit these complications or allow a problem to be more easily recognized.
Conclusion In conclusion, when appropriately used, surgical drains may be of significant benefit to the clinician and patient and can optimize wound healing. When used incorrectly, however, at best they are an unnecessary expense and at worst could result in a fatal complication (such as a multi-resistant infection causing septicemia or serious damage to a thoracic drain that could result in pneumothorax, lung collapse, and death).
REFERENCES 1. Hampel NL, Johnson RG. Principles of surgical drains and drainage. J Am Anim Hosp Assoc 1985;21:21–8. 2. Hunt GB, Tisdall PLC, Liptak JM, et al. Skin-fold advancement flaps for closing large proximal limb and trunk defects in dogs and cats. Vet Surg 2001;30: 440–8. 3. Lidbetter DA, Williams FA, Krahwinkel DJ, et al. Radical lateral body-wall resection for fibrosarcoma with reconstruction using polypropylene mesh and a caudal superficial epigastric axial pattern flap: A prospective clinical study of the technique and results in 6 cats. Vet Surg 2002;31: 57–64. 4. Remedios AM, Bauer MS, Bowen CV. Thoracodorsal and caudal superficial epigastric axial pattern skin flaps in cats. Vet Surg 1989;18:380–5. 5. Gurusamy KS, Samraj K. Wound drains after incisional hernia repair. Cochrane Database Syst Rev 2007;(Issue 1). Art. No.: CD005570. 6. Samraj K, Gurusamy KS. Wound drains following thyroid surgery. Cochrane Database Syst Rev 2007;(Issue 4). Art. No.: CD006099. 7. Parker MJ, Livingstone V, Clifton R, et al. Closed suction surgical wound drainage
8.
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after orthopaedic surgery. Cochrane Database Syst Rev 2007;(Issue 3). Art. No.: CD001825. Bohling MW, Henderson RA, Swaim SF, et al. Cutaneous wound healing in the cat: a macroscopic description and comparison with cutaneous wound healing in the dog. Vet Surg 2004;33: 579–87. Bohling MW, Henderson RA, Swaim SF, et al. Comparison of the role of the subcutaneous tissues in cutaneous wound healing in the dog and cat. Vet Surg 2006;35:3–14. Freeman LJ, Pettit GD, Robinette JD, et al. Tissue reaction to suture material in the feline linea alba. A retrospective, prospective and histologic study. Vet Surg 1987;16:440–5. Runk A, Allen SW, Mahaffey EA. Tissue reactivity to poliglecaprone 25 in the feline linea alba. Vet Surg 1999;28: 466–71. Brockman DJ, Pardo AD, Conzemius MG, et al. Omentum-enhanced reconstruction of chronic nonhealing wounds in cats: techniques and clinical use. Vet Surg 1996;25:99–104. Lascelles BDX, Davison L, Dunning M, et al. Use of omental pedicle grafts in the management of non-healing axillary
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wounds in 10 cats. J Small Anim Pract 1998;39:475–80. Langley-Hobbs SJ, Keller M, Voss K. External coaptation. In: Montavon PM, Langley-Hobbs SJ, Voss K, editors. Feline orthopedic surgery and musculoskeletal disease. Edinburgh: Elsevier; 2009. p. 239–48. Dernell WS. Initial wound management. Vet Clin North Am Small Anim Pract 2006;36:732–4. Ladlow JL. Surgical drains in wound management and reconstructive surgery. In: BSAVA manual of canine and feline wound management and reconstruction. Gloucester UK: BSAVA; 2009. p. 54–68. Halfacree ZJ, Wilson AM, Baines SJ. Evaluation of in vitro performance of suction drains. Am J Vet Res 2009;70: 283–9. Lee AH, Swaim SF, Henderson RA. Surgical drainage. Comp Cont Educ Pract Vet 1986;8:94–103. Monnet E. Pleura and pleural space. In: Slatter D, editor. Textbook of small animal surgery. Philadelphia: Saunders; 2003. p. 387–405. Valtolina C, Adamantos S. Evaluation of small-bore wire guided chest drains for management of pleural space disease. J Small Anim Pract 2009;50:290–7.
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Surgical drains L.J. Owen
Surgical drains can be valuable adjuncts to patient management, both in superficial locations and within body cavities; however, their use is not without risks or complications. Used correctly, surgical drains promote wound healing, reduce infection rates, and decrease patient morbidity, but used inappropriately these potential benefits can be reversed. In particular, drains should not be used as an alternative to appropriate wound debridement, lavage and suction, and meticulous wound closure. Surgeons should consider carefully the pros and cons of drain use before placement. A thorough understanding of the types of drain available, their advantages and disadvantages and correct method of placement, will help ensure that they are used in an optimal fashion.
INDICATIONS Surgical drains perform three main functions:
• Obliteration of dead space • Removal of pre-existing fluid or air from a wound/body cavity • Preventing anticipated fluid or air accumulation within a wound/body cavity. Whilst the first two therapeutic functions are widely accepted, the latter prophylactic use of surgical drains can be a controversial area. The use of a surgical drain to obliterate dead space is most commonly employed following en-bloc resection of neoplastic masses or chronic, contaminated and infected wounds. The definitive loss of tissue in these situations means that closure of individual wound layers is impractical and placement of a wound drain functions to appose tissue layers and promote healing. The use of surgical drains to remove pre-existing fluid or air is most commonly from a fluid-filled peripheral swelling, e.g., salivary mucocele or abscess, or from a body cavity. The removal of fluid from a surgical site is desirable due to the negative effects of the fluid on the host’s resistance to infection.1 This occurs via several mechanisms (Box 11-1). Drains are placed routinely during thoracic surgical procedures to evacuate postoperative pneumothorax and to remove either pre-existing or anticipated fluid, which may cause respiratory compromise. In the abdomen, drains are used predominantly for the purposes of removing septic exudate, e.g., in cases of septic peritonitis. Removal © 2014 Elsevier Ltd DOI: 10.1016/B978-0-7020-4336-9.00011-1
of transudates, modified transudates or blood is rarely of benefit to the patient. The most common indication for the prophylactic placement of a surgical drain is in combination with reconstructive surgery and the use of cutaneous and myocutaneous flaps. There is evidence within the veterinary literature that seroma formation is a common sequel to these procedures and that drain placement reduces the prevalence of this and subsequently of wound dehiscence and flap failure.2–4 Whether or not prophylactic drain placement is beneficial following other surgical procedures, however, remains controversial. In human medicine, Cochrane Systematic Reviews investigating the prophylactic use of surgical drains in orthopedic surgery, thyroid surgery, and incisional hernia repairs have failed to show any benefits in drain placement, but have shown some clear disadvantages, e.g., prolongation of hospital stay.5–7 In veterinary medicine, there is a distinct lack of published data on this subject, eliminating the use of an evidence based approach; thus surgeons are reliant upon anecdotal evidence and their own experience to determine whether a drain should be placed in any individual case. Experimental studies have documented prolonged tissue healing and reduced blood supply to cutaneous wounds in the cat compared with the dog, which may predispose to seroma formation in cats; however, clinical studies to support this have not been performed.8–11 In addition, cat owners may be poorly compliant at restricting exercise, allowing behavior such as jumping, which may contribute to problems with wound healing and seroma formation.
ALTERNATIVES TO SURGICAL DRAINS In some patients or for certain surgical procedures, it may be more appropriate to consider alternatives to the use of a surgical drain, such as incomplete wound closure, omental pedicle flaps or bandaging.
Incomplete wound closure The most distal portion of a surgical wound can be left open to provide drainage, and is a simple, cheap and usually effective method of preventing fluid accumulation within a surgical site postoperatively.
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Figure 11-1 Omentum tunneled from a paracostal abdominal exit point for placement into a chronic axillary collar wound. Small arrow, paracostal incision; arrowhead, axillary wound with omentum in place.
Box 11-1 The negative effects of fluid accumulation at surgical sites • Reduced ability to opsonize bacteria for phagocytosis • Reduced access of phagocytes into the wound • Ability of the fluid to act as a substrate to promote bacterial growth • Reduced vascular supply to tissues • Reduced penetration of systemically administered antibacterial agents into the surgical site
Figure 11-2 Penrose drains: 1 inch and 0.25 inch.
poorly tolerant of dressings and their presence may reduce feeding and normal behavior postoperatively.
TYPES OF DRAINS Drains are generally categorized according to function, i.e., whether they act as a passive route for passage of fluids or if they have a more active role in drainage.
Passive drains This technique can also be applicable to body cavities, particularly in the treatment of septic peritonitis by open peritoneal drainage. The main disadvantages of this technique are the increased risk of wound infection, reduced wound healing, and requirement for bandaging to collect the fluid.
Passive drains provide an exit point for fluid from a surgical site postoperatively, but do not actively reduce dead space within a wound and do not provide optimal drainage of air. Several types of passive drain exist, including Penrose drains, tube drains, sump drains, and corrugated drains; however, only the former are commonly in use in companion animal medicine and thus the others will not be considered further here.
Omentum
Penrose drains
Omentum can be used as an autogenous wound drain (Fig. 11-1). Its beneficial properties include promotion of angiogenesis, improved immune function, and tissue fluid drainage and it has been used successfully to promote healing of a variety of wound types in cats, particularly axillary collar wounds (see Chapter 18) and indolent pocket wounds, which are both challenging to treat by other methods.12,13 The use of omentum is, however, limited by its availability and the location of the wound: complications such as necrosis of the omental fat and incisional herniation through the omental exit point from the abdominal cavity have been reported.12 For information on how to create an omental flap see Chapter 19.
Penrose drains are composed of soft latex and are a flattened tube of variable diameter (0.25–1 inch) (Fig. 11-2). They are readily available, easy to use and cheap, making them a popular choice. This type of drain relies on gravitational forces, capillary action and overflow for wound drainage and therefore is limited to use in locations where these forces can be utilized. Penrose drains placed on the head or dorsum, or exiting from the lateral or dorsal aspects of a surgical site are unlikely to function and will instead contribute to complications of wound healing. The gravitational and capillary action of fluid drainage is related to the surface area of the drain and thus fenestration of these drains is contraindicated. In addition to reducing the efficiency of the drain, fenestration will also predispose to breakage of the drain during removal. Penrose drains are indicated for use in superficial wounds where there is pre-existing or anticipated fluid production and should have a single ventral exit point. Allowing the drain to have a second exit point proximally is not recommended.15 This serves only to increase the risk of wound infection and air transmission through the wound, without conferring any advantages to the patient. The main use of the
Pressure bandage The use of a bandage to maintain apposition of tissue planes is a suitable alternative to a surgical drain in some locations, e.g., distal limb.14 However, there are many anatomical locations where application of a bandage is difficult or where it may compromise normal function, e.g., cervical and thoracic regions. In addition, cats are often
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Surgical drains
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Box 11-2 Penrose drain placement The drain insertion and surgical site is clipped and aseptically prepared according to standard techniques. The distal portion of the drain is placed to exit through a stab incision in the most dependent area of the surgical site (Fig. 11-3A). This stab incision must always be separate from the main surgical wound and the size of the drain exit hole should be minimized to reduce the risk of herniation of fat/other organs, although it should not restrict fluid flow. The proximal aspect of the drain is secured to the skin at the dorsal limit of the wound with a single non-absorbable external skin suture (Fig. 11-3B). The ends of this suture are commonly left longer than the standard skin sutures to allow the drain suture to be identified at time of drain removal. The distal portion of the drain is cut to leave approximately 2–3 cm of drain visible from the exit site and the drain is secured at this site with a second single nonabsorbable skin suture, to prevent retraction of the drain into the subcutaneous space (Fig. 11-3C). The total length of the drain is recorded at time of insertion so that this can be verified at time of drain removal. The skin surrounding the drain is protected from fluid scalding with petroleum jelly or similar. A sterile and absorbent bandage is applied over the drain wherever possible to reduce contamination postoperatively.
Penrose drain removal To remove the drain, the two non-absorbable sutures (proximal and distal) are cut and the drain is gently pulled through its original exit site. The exit site is left to close by secondary intention healing. Consider culture of the drain tubing after removal if there are any concerns about infection.
A
B
C
Figure 11-3 Penrose drain placement. (A) A stab incision is made away from the main suture line of a surgical wound and a Penrose drain is drawn through this incision into the wound. (B) The proximal part of the Penrose drain is secured to the skin by a simple interrupted suture. (C) Following closure of the main surgical wound, only a small portion of the distal Penrose drain is visible exiting from a single point in the dependent part of the surgical site and secured by a simple interrupted suture.
double exit technique has traditionally been to prevent subcutaneous emphysema developing in areas of high motion, e.g., the axilla or inguinal region, where air may be sucked into the wound by a single exit point; however, this is not usually considered to be a significant clinical problem.16 After placement, where location permits, the drain should be covered by a sterile absorbent contact layer and bandage. This is for collection of the fluid produced, and to reduce the risk of introduction of hospital or environmentally acquired pathogens. The dressing should be changed according to the rate of fluid production from the wound. In locations where bandaging is not possible or would likely result in additional complications, petroleum jelly or similar is applied liberally to the clipped area ventral to the drain to prevent fluid from scalding the skin and to allow easy cleaning of the area. The problems of feline intolerance to dressings and requirements for sedation for dressing changes, thus increasing morbidity and cost, should be taken into consideration when using these drains. The technique of drain placement and removal is described in Box 11-2.
Tube drain A simple plastic or rubber tube drain can also be used to provide passive drainage. The advantage over a Penrose drain is that the tube does not collapse and thus drainage of fluid may be more rapid and air can more readily be removed from a wound (Fig. 11-4); however, they are likely to cause increased patient discomfort due to their rigidity and they may become occluded during use. Tube drains may also be placed to allow instillation of local anesthetic agents into a surgical site postoperatively, rather than to provide drainage from the wound. The same drain should not be used for both purposes due to the risk of introducing pathogenic organisms.
Figure 11-4 Placement of a passive tube drain to allow exit of air following a dorsal rhinotomy in a cat. (© Adrian Wallace.)
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Diagnostics, Equipment and Implants
Active drains Active drainage is created by application of a vacuum to a wound drain. These drains are generally easier to manage in comparison to passive drains and have reduced risk of ascending infection.
Closed suction drains This type of drain is commonly used in superficial surgical sites, to obliterate dead space, to remove pre-existing fluid and air, or to prevent formation of fluid within the site postoperatively. Several commercial suction drains are available, which consist of a rigid, non-collapsible tube drain attached to a collection chamber (compressible or pre-applied vacuum); however, their size and weight need to be considered before their application to cats. The smaller, concertina/grenade type drains are appropriate in most cases and are often very effective (e.g., Mini Red-O-Pack drains or Jackson Pratt drains) (Figs 11-5 and 11-6). As well as being a suitable size, in experimental studies these drains have been shown to operate at a lower
pressure and in a more consistent manner compared to rigid drains; thus minimizing the effect of the drain itself on fluid production within the wound.17 Application of suction to these drains results in a negative pressure of approximately −80 to −120 mmHg within the wound, which is sufficient to obliterate dead space without excessively traumatizing the soft tissues.1,17,18 As the reservoir becomes filled, the negative pressure generated reduces and the drain becomes less efficient; although the Jackson Pratt and Mini Red-O-Pack drains have been shown to maintain suction at a lower level throughout filling of the reservoir.17 Homemade closed suction drains can be particularly useful in cats due to their reduced weight, size, and cost. Two main variations are reported. For both types, the portion of the drain that is to be placed in the wound is made from a 19G butterfly catheter, which has had multiple fenestrations made into the tubing. These fenestrations should not exceed 30% of the tube diameter, to reduce the risk of the tube kinking or breakage of the tubing on removal.16 The needle from the butterfly catheter can then be placed into a standard blood collection vacutainer (ideally made of plastic rather than glass) to provide suction (Fig. 11-7). Alternatively, the butterfly catheter tubing can be connected to a syringe. The syringe plunger is withdrawn to apply suction and a hypodermic needle is placed across the syringe case to maintain this suction. Both drains are then secured to the trunk with additional sutures or a mesh stockinette. These drains are usually only suitable for use in wounds where minimal fluid production is expected, due to the limited capacity of the collection device. Continuous suction devices are considered optimal for wound care, but more simple constructions utilizing intermittent suction may have some suitable applications. Closed suction drains have several advantages over passive drains (Box 11-3). The disadvantages are increased cost (which may be offset
Box 11-3 Advantages of closed suction drains
Figure 11-5 Mini Red-O-Pack closed suction drain. (With permission from Vygon Vet.)
Figure 11-6 Reconstruction of a large soft tissue deficit, following en-bloc resection of a fibrosarcoma from the left flank, using a caudal superficial epigastric skin flap. A mini Red-O-Pack closed suction drain has been placed, in addition to a tube drain for instillation of local anesthetic agents. (With permission from Vygon Vet.)
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• • • • • • •
No bandaging required Reduced risk of nosocomial infections Work independent of gravity Fluid production can readily be quantified Fluid can easily be sampled for repeat cytological examination Fluid and air are more efficiently removed Reduced risk of tube occlusion when continuous suction is used.
Figure 11-7 Application of a homemade butterfly catheter closed suction drain, following an omocervical axial pattern flap in a cat.
Surgical drains
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Box 11-4 Closed suction drain placement The drain insertion and surgical site is clipped and aseptically prepared according to standard techniques. The drain tubing is placed within the wound so that all fenestrations lie subcutaneously, thus allowing an airtight seal to form. An exit point for this tubing is made away from the main surgical wound via a stab incision or by using the needle attached to the tubing that is provided in some commercial kits. For closed suction drains, the exit point of the drain does not need to be at a dependent point and therefore can be placed so as to make drain management easier and its position more comfortable for the patient. At the exit point, the drain is secured to the skin using a Roman sandal suture (Fig. 11-8). A sterile adhesive dressing is applied around the exit point of the drain to keep this area as clean as possible. The drain tubing is connected to the collection chamber, which is activated immediately if an airtight seal has been achieved using wound closure alone, or after 6–8 hours once a fibrin seal has formed. The collection chamber is secured to the patient using further sutures or a stockinette dressing or both.
A
Closed suction drain removal Removal of the drain is accomplished by cutting all of the securing sutures, followed by withdrawal of the tubing from the wound. The exit site is left to close by second intention healing. Consider culture of the drain tubing after removal if there are any concerns about infection.
B Figure 11-9 (A) 14G wire-guided thoracic drain. (B) Close up of the tip showing the fenestrations (with permission from MILA International, Inc. www.milaint.com).
Figure 11-8. A Roman sandal friction suture is used to secure drain tubing to the skin.
by the cost of the dressings and the sedation required for management of a passive drain) and potential occlusion of the drain or reflux of fluid back into the wound. The technique for insertion of active drains is described in Box 11-4.
THORACIC DRAINS Three main types of thoracic drain are available for use in small animals: trocar drains, non-trocar drains, and Seldinger-type drains. All three are suitable for use in cats; however, the Seldinger-type is increasing in popularity for use in this species due to the small diameter of the drain, which is associated with a significant reduction in patient discomfort and morbidity. Trocar and non-trocar drains are available in a range of sizes; 10–16 Fr are most commonly used in cats.18 Traditionally, the size of drain selected should approximate the diameter of the mainstem
bronchus;19 however, smaller lumen drains reduce discomfort and thus may be preferable in many situations. Both of these drain types require sedation, or more commonly general anesthesia, for placement in a cat, and can be placed under direct observation during surgery, or as an extra-thoracic technique. Placement of these drains requires considerable force to pass them through the intercostal musculature and a particular concern when dealing with small patients such as cats, with high thoracic wall compliance, is the risk of iatrogenic damage to the heart/lungs/vessels in the thorax during placement. The Seldinger-type thoracic drains are relatively new in veterinary medicine and are more expensive, but have some significant advantages over the wide-bore drains. The most commonly used drain is 14G in size (Fig. 11-9) and the atraumatic technique with which it is placed means that local anesthesia or mild sedation is often sufficient, avoiding the need for, risks associated with, and cost of general anesthesia. A potential disadvantage often cited is the risk of occlusion of the narrow bore tube with thicker effusions, e.g., pyothorax; however, in a recent veterinary study this was not found to be a significant problem.20 The small size of these drains results in a significant reduction in postoperative morbidity, particularly in cats due to their relative smaller chest size and therefore the author considers these thoracic drains to be optimal for use in the majority of feline patients. The technique of placement of thoracic drains is covered in Chapter 41.
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Diagnostics, Equipment and Implants confers no additional advantage, but increases the risk of infection due to increased drain handling. Dressing changes should be performed as aseptically as possible and the drain exit site should be examined at least once daily for the presence of erythema, discharge or swelling.
WHEN TO REMOVE
Figure 11-10 Jackson Pratt abdominal drain placed for postoperative management of septic peritonitis in a cat.
ABDOMINAL DRAINS The Jackson Pratt closed suction drain (Fig. 11-10) is the most common type used for drainage of the abdominal cavity. This is a wide, flat silicone drain, with multiple fenestrations, which reduces the occurrence of drain occlusion during use. The flat portion of the drain merges into tubing, which exits the body wall and attaches to a grenade type collection chamber. Usually, the drain is positioned to lie along the ventral midline of the abdominal cavity, where the majority of fluid will collect due to gravitational forces. Drain use within the abdominal cavity is restricted to situations where ongoing fluid production is expected, e.g., in cases of septic peritonitis where the cause remains unresolved. The advantage of placing a drain is that it allows monitoring of the nature of the fluid produced within the abdomen and repeat cytological analysis to assess for improvement or deterioration of the patient’s condition. The main disadvantages are occlusion of the drain by omentum and fibrin, the increased risk of wound dehiscence if the drain is placed too close to an intestinal or other organ incision, and the additional expense of these drains. More details on indications and placement of this type of drain will be covered in Chapter 26.
POSTOPERATIVE CARE An Elizabethan collar is mandatory for all patients with a surgical drain in place, to prevent premature removal or damage to the drain. In some cats and depending upon the location of the drain, it may be possible to use a soft collar to allow them to feed more easily and to avoid problems with postoperative anorexia. If a rigid collar is deemed necessary, it may need to be removed under close observation at feeding times. Drains are likely to add to patient discomfort in the postoperative period and appropriate analgesia should be supplied while they are in place. Nosocomial infections are a significant risk of drain placement and can lead to multi-resistant wound infections and costly complications. Gloves should ALWAYS be worn when handling the drain or the surgical site. In addition, closed suction drains should only be emptied once they become full, or if suction is lost. More frequent emptying
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All surgical drains will act as foreign material within the surgical site and as such will result in soft tissue irritation and inflammation. This inflammatory response will elicit some fluid production independent of the surgical disease and thus fluid production from the drain is rarely expected to reduce to zero after placement. As a general guide, approximately 2–4 mL/kg/24 hours is deemed to be acceptable and likely to be solely due to drain presence; thus when fluid production reduces to this level, the drain can be removed. Alternatively, where this level is not reached, but the quantity of fluid drained remains static over two to three days, the drain should also be removed. In order to use these guidelines, it is important that fluid production is accurately quantified when drains are emptied, and recorded so that the 24 hour rate of fluid production can be calculated. Because of the difficulty of quantifying fluid production from Penrose drains, these drains are usually removed when fluid production has become serosanguinous/transudate in nature and the amount of fluid is subjectively considered to be decreasing or is unchanged over a number of days. This commonly occurs by day 3 to 5 postoperatively. Delay in removal of the drain beyond this point is generally not recommended, as the advantages of continued drain placement reduce, and the risks of infection and costs of bandaging and hospitalization increase.
COMPLICATIONS Infection Removal of fluid from a surgical site is known to be beneficial in reducing infection, because the presence of fluid interferes with opsonization of bacteria, phagocytosis and antibacterial agent penetration. In contrast however, the presence of the drain within the wound may decrease the host’s innate resistance to infection and handling of the drain in the postoperative period, often by multiple nursing personnel, carries an inherent risk of introducing nosocomial organisms into the wound. These latter infections may involve organisms with increased pathogenicity compared to original wound contaminants and thus infection with these organisms can greatly increase morbidity or result in patient mortality in the worst case scenario. This means that when drains are used optimally and are active in removing fluid from a wound/resolving dead space, they are likely to be advantageous in fighting infection. If drains are, however, used in a prophylactic setting only, or are poorly managed postoperatively, the overall effect may be more detrimental than beneficial to the individual.
Wound dehiscence Drains placed to exit through the main wound incision result in increased wound dehiscence and therefore they are always placed to exit at a separate and distant site. Placement of drains within the abdomen adjacent to sites of intestinal anastomosis or incisions into other organs has been shown to increase the risk of wound dehiscence in human beings and the same is likely to be true in animals.
Surgical drains
Occlusion This is a problem of tube drains, which are prone to becoming occluded during use. Occlusion generally occurs by one of three mechanisms: the fluid exiting the drain is too viscous for the size of the drain tubing; fluid production has significantly reduced and thus consolidation of material is allowed to occur within the tubing; or the drain holes within the wound/body cavity have become occluded by fibrous tissue or omentum. Once a drain has become occluded, the clinician must decide upon the next course of action. If fluid production has significantly reduced, removal of the drain would be the most appropriate action. If, however, the function of the drain is still required, the clinician can attempt to aspirate the clot from the tube or a new drain may need to be placed.
Premature drain removal Cats are fastidious groomers by nature and will show a keen interest or dislike to foreign objects and sutures attached to their body. If the drain is accessible to them, it is likely to be removed by the patient and thus an Elizabethan collar is necessary in all cases to prevent this
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from occurring. Premature drain removal may result in unwanted fluid build-up within the surgical site or the need for repeat placement of the drain under a second anesthetic or sedation.
Drain retention or breakage Retraction of the drain back into the wound bed or breakage of the drain during removal can occur. Recording the length of drain initially placed within the wound, using only radio-opaque drains and adequately securing drains at the exit site should limit these complications or allow a problem to be more easily recognized.
Conclusion In conclusion, when appropriately used, surgical drains may be of significant benefit to the clinician and patient and can optimize wound healing. When used incorrectly, however, at best they are an unnecessary expense and at worst could result in a fatal complication (such as a multi-resistant infection causing septicemia or serious damage to a thoracic drain that could result in pneumothorax, lung collapse, and death).
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