Asuction drain is a closed-tube drain used to evacuate fluid from a wound or cavity into an attached reservoir following a differential pressure gradient. Suction drains are routinely used in clinical veterinary practice. A wide range of systems are available with different methods of operation.1 These can be broadly divided into systems with compressible reservoirs, which require evacuation of air by compression to create suction, and systems with rigid reservoirs, which provide suction by prior evacuation of air. There is little information available regarding the functional characteristics of drainage systems, including the initial suction pressures generated, how this changes as the reservoir fills, and how this varies among systems.
The suction pressure generated by suction drains will impact on drain system function. Excessive suction pressure may increase the volume and duration of fluid drainage,2 and inadequate suction may result in ineffective drainage. Starling's law of transvascular fluid exchange3,4 states that the balance between hydrostatic and oncotic pressure gradients in the intravascular and interstitial space determines fluid flow between these compartments. Therefore, as the suction pressure increases, so will the amount of fluid that is produced in the wound above that which would develop following surgery or trauma alone in an undrained wound.5 In fact, experimental systems generating suctions between 50 and 200 mm Hg are used to produce effusion fluid for sample collection from the SC space.6,7 Because the duration for which a drain remains in place is often dictated by the volume of fluid accumulating in the reservoir,8 an increased volume of fluid collection may result in the drain remaining in place for longer, which may also dictate an extended hospitalization period.2 Results of studies9–11 in the human medical literature also indicate that excessive pressure can cause tissue damage.
The use of invasive devices, including suction drains, is associated with an increased rate of hospital acquired infection and surgical site infection in humans, and this is becoming an increasingly apparent problem in veterinary patients.12 It is recognized that the presence of foreign material within a wound reduces the number of microorganisms required for infection by 10,000 fold.13 An increased rate of wound infection or inflammation in association with the use of surgical drains has been documented in a prospective study14 of surgical site infection in dogs and cats. The use of active suction drains reduces surgical site infection, compared with the use of open passive drains15; the constant negative pressure generated by the system minimizes the potential for retrograde flow of bacteria and fluid.16 If suction is lost as the closed system fills, this protective effect is lost and the active removal of wound fluid will cease. An understanding of the functional characteristics of different systems will provide information to guide their use and design, allowing selection of appropriate suction drains for use in clinical cases. An improved understanding of the effects of drain use on fluid production in the wound may be used to optimize the duration of drain use, which may have an impact on duration of hospitalization, patient morbidity, and risk of hospital-acquired infection.
The clinical assessment of drain efficacy and decisions made regarding time of drain removal are largely based on the volume of fluid accumulating in the reservoir. It is therefore important that the function of the drainage system used is predictable and consistent. The drainage system should maintain suction to complete filling of the reservoir therefore allowing the clinician to accurately assess ongoing fluid accumulation in the reservoir as representative of ongoing fluid production in the wound. While the drain reservoir is not full, the clinician may assume that the drain remains functional, although in fact, there is no ongoing drainage. In this circumstance, fluid may continue to accumulate in the wound. There would also be the potential for retrograde movement of fluid in the drain tubing, leading to an increased risk of postoperative wound infection. This potential risk underscores the need for maintaining a negative pressure gradient and the need for aseptic technique when emptying the drain reservoir. An ideal drainage system should maintain suction pressure until complete filling of the reservoir and exert adequate but not excessive suction, therefore promoting fluid drainage but not inciting increased fluid production or causing tissue damage.
The aim of the study reported here was to assess the in vitro functional characteristics of commercially available active suction drainage systems used by specialist veterinary surgeons working in the United Kingdom. Objectives included determination of maximum initial suction generated by the drainage systems and how this may be affected by variation in operator use, determination of pressure-volume relationships during filling of the reservoir with water or air, and assessment of the maximum volume of water aspirated by use of the drainage systems set at the maximum initial suction. The initial suction generated by the drainage systems and their pressure-volume relationships during filling were hypothesized to vary widely among systems.
Grenade-type 100-mL drain
Grenade-type 400-mL drain
Concertina-type brand A 20-mL drain
Concertina-type brand A 50-L drain
Concertina-type brand B 25-L drain
Concertina-type brand B 400-mL drain
Concertina-type brand C 120-mL drain
Pancake-type 200-mL drain
Rigid-type brand A 200-mL drain
Rigid-type brand A 400-mL drain
Rigid-type brand B 400-mL drain
Jackson Pratt 100 mL, Cardinal Health, Swindon, England.
Jackson Pratt 400 mL, Cardinal Health, Swindon, England.
Mini Redon 20 mL, Primed, Halberstadt Medizintechnik, Halberstadt, Germany.
Mini Redon 50 mL, Primed, Halberstadt Medizintechnik, Halberstadt, Germany.
B Vak mini wound drainage system, 25 mL, Biçakcilar, Istanbul, Turkey.
B Vak wound drainage system 400 mL, Biçakcilar, Istanbul, Turkey.
Vygon 120 mL, Vygon, Ecouen, France.
Wound Evac 200 mL, Microtec Medical, Staffordshire, England.
Privac 200 mL, Primed, Halberstadt Medizintechnik, Halberstadt, Germany.
Privac 400 mL, Primed, Halberstadt Medizintechnik, Halberstadt, Germany.
Braun Redovac 400 mL, B Braun, Sheffield, England.
Part No. 235 5790, RS components, Corby, Northants, England.
Smiths Medical, Kirchseeon, Germany.
Little Herbert, SurgiVet, Waukesha, Wis.
Jelco IV catheter, Medex Medical, Haslingdon, England.
Fluke 25 multimeter, RS components, Corby, Northants, England.
Manson EP-613, 0 to 30 V, 2.5 A DC Power Supply, Manson Engineering Industrial Limited, Hong Kong, People's Republic of China.
StatView for Windows, version 5.01, SAS Institute Inc, Cary, NC.
Miller CW. Bandages and drains. In: Slatter D, ed. Textbook of small animal surgery. 3rd ed. Philadelphia: Elsevier Science, 2003;244–249.
Chintamani, Singhal V, Singh JP, et al. Half versus full vacuum suction drainage after modified radical mastectomy for breast cancer—a prospective randomized clinical trial [ISCRCTN24484328]. BMC Cancer 2005;5:11.
Landis EM. Micro-injection studies of capillary permeability. II. The relation between capillary pressure and the rate at which fluid passes through the walls of single capillaries. Am J Physiol 1927;82:217–238.
Starling EH. On the absorption of fluids from the connective tissue spaces. J Physiol (Lond) 1896;19:312–326.
Willy C, Sterk J, Gerngross H, et al. Drainage in soft tissue surgery. What is “evidence based”? [in German]. Chirurg 2003;74:108–114.
Kayashima S, Arai T, Kikuchi M, et al. Suction effusion fluid from skin and constituent analysis: new candidate for interstitial fluid. Am J Physiol Heart Circ 1992;263:1623–1627.
Svedman C, Yu BB, Ryan TJ, et al. Plasma proteins in a standardised skin mini-erosion (II): effects of extraction pressure. BMC Dermatol 2002;2:4.
Merad F, Yahchouchi E, Hay JM, et al. Prophylactic abdominal drainage after elective colonic resection and suprapromontory anastomosis. Arch Surg 1998;133:309–314.
Ogeer-Gyles JS, Matthews KA, Boerlin P. Nosocomial infections and antimicrobial resistance in critical care medicine. J Vet Emerg Crit Care 2006;16:1–18.
Mangram AJ, Horan TC, Pearson ML, et al. Guideline for prevention of surgical site infection. Infect Control Hosp Epidemiol 1999;20:247–278.
Eugster S, Schawalder P, Gaschen F, et al. A prospective study of post-operative surgical site infections in dogs and cats. Vet Surg 2004;33:542–550.
Cruse PJ, Foord R. The epidemiology of wound infection. A 10-year prospective study of 62,939 wounds. Surg Clin North Am 1980;60:27–40.
Alexander JW, Korelitz J, Alexander NS. Prevention of wound infections. A case for closed suction drainage to remove wound fluids deficient in opsonic proteins. Am J Surg 1976;132:59–63.
Adaptors used for connection of each drain tube to the Luer-lock of the 3-way stopcock.
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