problem wounds and drains

Learning Objectives

• Understand strategies for dealing with infected wounds
• Understand and describe the consequences of improper treatment of infected wounds
• Describe the management of foreign bodies and internally penetrating wounds
• Describe the distinction between active and passive drains
• Identify means of producing active or passive drainage
• Describe scenarios that may benefit from surgical drainage
• Describe drainage of the chest and abdomen

Factors Affecting Wound Healing

• Patient factors:
  • Poor nutrition/malnourishment (low protein levels)
  • Concurrent disease (hyperadrenocorticism, hypothyroidism, cancer)
  • Immunosuppressive drugs/chemotherapy
  • Cat vs. dog wound interference
• Wound factors:
  • Blood supply
  • Perfusion
  • Infection/Contamination
  • Tissue viability/fluid accumulation
  • Movement/pressure/skin tension
  • Neoplasia

Problem Wounds

• Disrupted wounds
  • Pressure wounds
  • Wounds in areas of movement and pressure

Factors Leading to Disrupted Wounds

• Wound tension
• Infection
• Haematoma or Seroma
• Suturing nonviable tissue
• Wound molestation

Dehiscence

• A topic likely covering wound separation

Halsted's Principles

• Gentle tissue handling
• Meticulous haemostasis
• Preservation of blood supply
• Strict aseptic technique
• Tension-free closure
• Accurate apposition of tissues
• Eliminate dead space

Pressure Wounds

• Decubital ulcers
• Bony prominences
• Greater trochanter
• Tuber coxae
• Acromion of scapulae
• Ischial tuberosity
• Lateral humeral epicondyle
• Lateral tibial condyle
• Lateral malleolus
• Sides of digit 5
• Olecranon
• Calcaneal tuberosity
• Sternum
• Repeated trauma (sitting/lying, tissue compression)
• Prolonged recumbency (neurological/spinal patients/multi orthopaedic patients)
• Bandage induced pressure sores

Prevention of Decubital Ulcers

• Turn recumbent dogs every 1-4 hours
• Meticulous nursing/skin care-clean and dry-well-padded bed
• Treat underlying condition to prevent recumbency
• Relieve pressure (donut dressing, splints)

Prevention of Bandage Sores

• Proper bandage placement and monitoring
• Prevent slipping, not overtight
• Careful padding over bony prominences
• Less is more with padding
• Care with rigid fixation (casting, splints)
• Place on opposite side of limb from healing wound
• Be aware of swelling
• Casting too early
• Use bivalve casts and check regularly

Movement and Pressure

• Wounds over joints (tension, compression, shearing forces)
• Meticulous attention to closure
• Casting/splinting
• Paw pad wounds (compression, weight-bearing)
• Suture pull through
• Spread with weight-bearing
• Bandaging/splinting (Palmar/plantar - prevent weight bearing on pad for 2 weeks)
• Tension relieving sutures
• Far-near-near-far, large diameter monofilament suture
• Eventually heal by granulation or owner will tolerate sock/bandage/clean walks

Chronic Wounds - Movement and Pressure

• Axillary and inguinal wounds
• Collar wounds
• Shearing movement with ambulation
• Meticulous closure
• Debride and close
• Resect and close
• Reconstructive flaps

Infected Wounds

• Inhibits wound healing
• Chronic/recurrent wounds
• Causes dehiscence of closed wounds
• Surface contaminants do not often reflect infective agent
• Deep tissue culture
• Nature of wounding
  • Puncture from a bite
  • Underlying causes
  • Foreign bodies
  • Grass seeds, sx implants, bone sequestra, debris/contaminants

Nature of Wounding

• More energy applied to tissues
• More vascular damage
• Less blood supply (less O2), fewer plasma proteins
• Slower inflammatory response, prolonged inflammation
• Contaminated bacteria more likely to cause infection
• Shearing creates dead space
• Penetrating FBs create dead space
• FBs create avascular surface for bacteria

Trauma, Contamination, and Infection

• Layers of skin (skin, subcutaneous tissue, muscle)
• Dead space (warm, moist, low O2, proteins, immune response cannot penetrate)

Trauma, Contamination, and Infection

• Immune response can only reach edges
• Walled off area
• Abscess

Trauma, Contamination, and Infection

• Heals by granulation
• Abscess bursts
• Drains

Foreign Bodies and Penetrating Wounds

• Wood splinters, grass awns, straw, broken teeth or nail of an attacker
• Common entry points
  • Interdigital
  • Ear canal
  • Conjunctiva
  • Oropharynx
• Draining tract/sinus
  • FBs
  • Surgical implants, sutures, cotton swab strands bone sequestra

Approach to a Draining Tract

• Diagnostics
  • Radiographs
  • Impression smear
  • Bacteriology
  • CT/MRI
• Surgical exploration
  • Identify and remove causes
  • Leave to heal by 2nd intention or excise tract en bloc
  • Tissue sample
  • Thoroughly lavage
  • Empirical antibiotics
• Change based on culture results

Penetrating Wounds – Cat Bite Abscess

• Cat bite abscess (punchure wounds with some crush injury)
• Clinical infection
• Presentation
  • Rapid, occurring swelling
  • Brave/timid cat
  • Ruptured/burst with no visible swelling
  • Systemically unwell (pyrexic, lethargic, painful)
  • Should be differential in cats with PUO (possible fever)
  • Lameness/ not using limb/tail
  • May occur where drainage is difficult

Cat Bite Abscess – Treatments

• Presented before abscessation:
  • No need to explore (low FB?)
  • Antibiotics
  • Pain relief (NSAIDs)
• Presented with abscessation:
  • Antibiotics that penetrate pus
  • Lance, drain, flush, place drain (dead space) antibiotics
  • Pain relief (NSAIDs)
• Bacteria: Pasturella, Staph, Strep (aerobes + anaerobes)
• Broad spectrum antibiotics (amoxy-clav, clindamycin, cephalosporins)

Oropharyngeal Penetrating Trauma – Stick Injuries

• Med to large breed dogs (collies, Labradors, spaniels)
• Acute (within 7 days of presentation)
  • Oral pain, dysphagia, dyspnea
  • Submandibular/cervical swelling
  • Abscesses, pain opening mouth
  • Pyrexia
  • Injury observed or knowledge of stick catching/carrying
• Chronic (>7 days before presentation)
  • More common
  • Systemically well
  • Recurrent cervical or submandibular swelling or discharging sinus
  • Rostral pharyngeal wounds
    • Enters at acute angle
    • Penetrates pharynx at tonsil
    • Can lead to involvement of temporal, masseter or retrobulbar muscles
  • Lateral pharyngeal wounds
    • Most common
    • Oblique entry damages para pharyngeal, cervical tissues, and intermandibular area to cranial thorax
  • Dorsal pharyngeal injuries
    • Enters in front of dog
    • Damages soft palate and dorsal pharynx
    • Can lacerate esophagus

Oropharyngeal Stick Injuries – Treatment

• Acute
  • Examine oral cavity and pharynx
  • Identify & remove foreign object
  • Cervical and thoracic radiographs
  • Soft tissue swelling (loss of detail, gas between tissue planes, subcutaneously, pneumomediastinum (if esophageal perforation)
  • Prevent chronic fistulous tracts: surgically explore via ventral midline approach, inspect dorsal esophagus for tears.
• Chronic
  • Recurrent cervical swellings and discharging sinuses
  • Original injury often unknown and difficult to treat
  • Meticulous exploration of tracts and debridement of all diseased tissue

Surgical Drains

• Tissue apposition and obliteration of dead space
• Remove fluid that provides media for bacterial growth
• Relieve pressure that can affect tissue perfusion
• Remove inflammatory mediators, bacteria, necrotic tissue, foreign material
• Drains incite inflammatory response
• Open drain (passive)
• Closed suction drain (active)

Comparison of Closed, Active Suction Drains vs Open, Passive Drains

• Path of drainage
• Fluid collection site
• Mechanism of action
• Exit site
• Monitoring fluid quantity
• Monitoring fluid character
• Relative risk for ascending infection
• Need fully closed wound
• Ability to collapse dead space
• Irritation of skin

Open Passive Drains

• Penrose drain
• Capillary action
• Gravity
• Drainage along outside of tube
• High surface area to volume ratio
• Fenestration contraindicated

Penrose Drains

• Advantages: inexpensive, soft/malleable, low tissue trauma
• Disadvantages: cannot quantify fluid production, not useful for large volume drainage, requires gravity, cannot use in thoracic cavity, more risk of ascending infection

Placing a Penrose Drain

• Proximal end deep in wound/dead space
• Exit via stab incision, dependent on wound
• Distal end secured to skin with single suture through drain
• Must not exit through incision
• Cover with dressing
• Do not use for flushing
• Secure proximal end with suture
• Care with neoplasia (place close to wound incision)
• Need to clean regularly and attempt to quantify drainage production

Closed Suction Drains (Active)

• Tubing and suction device/vacuum
• Fenestrations
• Airtight cavity
• Less risk of contamination
• More effective fluid removal
• Reduced risk of ascending infection
• Easily portable
• Doesn't require a lot of dressing
• Can collect and record fluid
• Constant suction decreases occlusion
• Loss of vacuum if not airtight
• Occlusion by clots
• Premature removal (BC often needed)

Placing a Closed Suction Drain

• From inside to outside
• Choose drain exit site (easy to cover, comfortable, manageable)
• Tunnel to site with forceps
• Incise skin over forceps
• Hole no larger than tubing (consider trocar)
• Handle tubing
• Fenestrated portion dependent
• Ensure fenestration in wound, allow suction
• Purse string suture and secure with finger trap
• Attach grenade

Activating Suction

• Best to wait 4-6 hours
• Compress grenade with evacuation port open
• Close the port/cap/clamp tubing
• Release compression to create negative pressure
• Cover exit site with adhesive dressing
• Use shirt/stockinette/bandage to protect tubing/grenade
• Use a buster collar if needed

Maintaining an Active Suction Drain

• Monitor and record fluid amount quality
• Empty drain daily or when half full
• Strength of suction dec as grenade fills

Drain Removal

• Passive drains: when fluid production slows
  • ~2-5 days
  • Cut one end prior to pulling
  • If anchoring suture, cut and remove in smooth motion
• Active drains
  • When fluid production <2-4mls/kg/24hrs
  • Usually 2-5 days
  • Gentle finger trap removal
• Measure drain to ensure complete removal
• Leave exit hole to heal by second intent

Ingress/Egress Drain Placement and Removal

• Useful in inguinal or axillary region
• To prevent suction drawing bacteria into the drain
• Pull one end, cut the ‘dirty’ end, put back in wound
• Pull the full drain out from stuck end

Top Tips for Drains

• Passive drains must be dependent
• Drains should not exit through incision
• Exit incision should be same width or slightly wider than active drains
• Place the drains from the inside out.
• Do not fenestrate Penrose drains!
• Flush Penrose drains (not advised)
• Remove drain as soon as possible
• Drains cause fluid production – unlikely to be zero fluid
• Measure the drain to ensure complete removal
• Leave exit holes to heal by second intention

Comparison of Active and Passive Drains

• How it works (active vs passive)
• Exit site
• Path of fluid
• Can you measure amount of fluid
• Ability to close dead space
• Requires airtight cavity
• Risk of contamination

Complications of Drains

• Increased risk of wound contamination and infection (ascending infections)
• Act as foreign bodies
• Increases with duration of drainage
• Increased with use for flushing the wound
• Converts a clean wound to a clean-contaminated one
• Patient interference: premature removal, breakage with drain in wound
• Drainage failure: improper placement/positioning, inadequate diameter, overfilling, suction system detachment, drain obstruction
• Local structures
• Erosion/seeding if neoplasia
• Breakage at removal (requires surgical retrieval)

Chest Drains

• Intermittent or continuous drains
• Remove when fluid production slows
• IV antibiotics if infection
• Precautions for sterility (nosocomial infection)
• Precautions to prevent patient interference

Chest Drainage – Thoracentesis

• Intermittent (every 4-6 hours)
• Easy to quantify amounts
• Works well for small volumes
• Can tell if volume decreasing

Chest Tube Placement

• Neurovascular bundle at caudal aspect
• Skin incision
• Subcutaneous tunnel
• J wire placement
• Small bore wire

Abdominal Drainage

• Palliative drainage of ascites (intermittent abdominocentesis)
• If septic peritonitis
  • Open drainage
  • Closed suction drain (Jackson-Pratt)
• Often get blocked or walled off

Small Bore Chest Tube

• Small bore chest tubes – video
• Mila Pneumothorax Catheter Placement https://vetgirlontherun.com/...

Step-by-Step Chest Tube Placement

• https://www.cliniciansbrief.com/article/chest-tube-placement
• Chest tube placement