Integument & eye Flashcards
Name causes of mydriasis / miosis (that are not related to brain injury)
- Mydriasis:
- Pharmacological: atropine (topical or systemic), tropicamide
- Glaucoma
- Lens luxation
- Optic neuritis
- Retinal detachment
- Chorioretinal inflammation
- Iris atrophy - Miosis:
- Pharmacological: latanoprost, pilocarpine
- Anterior uveitis
- Horner’s syndrome
- Corneal ulcer
What is the desired pressure to flush wounds
7-8 psi (can be achieved by using a 0.9 NaCl in a pressure sleeve at 300 mHg)
Recommended to use a 60 mL syringe with an 18 Ga (=pink) needle or a 35 mL syringe with a 19 Ga (=cream) needle
What is lagophtalmos
Lack of complete eyelid closure
What are signs of an infected corneal ulcer and what is the recommended treatment
Any corneal ulcer with stroma involvement is considered infected. Stromal infiltrates, corneal malacia, and reactive anterior uveitis can also be present.
Treatment:
- Broad spectrum antibiotics combining a fluoroquinolone (ciprofloxacin) + cefazolin or neomycin-polymixin-gramicidin or tobramycin -> every 15min for first hour then every 2h until signs of resolution
- Antifungal (voriconazole) if fungal infection is suspected
- Antiprotease (serum) if keratomalacia -> every 2h until signs of resolution
- Atropine for comfort (mandatory if anterior uveitis is present) IF IOP NOT ELEVATED
- Systemic NSAID if uveitis is present (topical NSAIDs to be avoided with ulcer)
What is the treatment for anterior uveitis? What is a common complication?
Treatment:
- Topical steroids if possible (otherwise topical NSAIDs but less efficient)
- Systemic steroids / NSAIDs if severe
- Atropine if IOP is low to low-normal - any elevated or high-normal IOP in the face of uveitis indicates glaucoma (in these cases atropine is contra-indicated and dorzolamide should be instituted)
What are treatments for glaucoma and their mechanism of action +/- contra-indications
- Prostaglandin analogs (Latanoprost) -> increase outflow of aqueous humor
Contra-indications: uveitis, anterior lens luxation - Carbonic anhydrase inhibitor (dorzolamide) -> decrease aqueous humor secretion
- Beta blockers (timolol) -> decrease aqueous humor production
Contra-indications: cardiac disease, asthma - IV mannitol -> osmotic “drainage” of aqueous humour
Contra-indications: uveitis (permeable blood-eye barrier), cardiac disease, dehydration
What are differentials for acute blindness
- Glaucoma
- Retinal detachment (eg. systemic hypertension)
- Retinal toxicity (eg. fluoroquinolones in cats, ivermectin in dogs)
- Uveitis
- Optic neuritis
- CNS disease
- Prolonged compression of maxillary artery in cats
- SARD (sudden acquired retinal degeneration)
What are the bacteria most commonly cultured from bite wounds
Pasteurella spp
Staphylococcus spp
Streptococcus spp
In 2 other studies says Staphylococcus, E Coli, and Enterococcus…
What is the classification of wounds
- Clean: atraumatic, surgically created under aseptic conditions
- Clean contaminated: minor break in aseptic surgical technique (eg. opened GI)
- Contaminated: Recent traumatic wound with bacterial contamination vs major break in surgical asepsis (eg. spilled GI content, all penetrating wounds)
- Dirty or infected: older wound with exudate or obvious infection –> >10^5 organisms/g of tissue
What are the phases of wound healing
- Inflammation and debridement (first 5 days after injury)
- Proliferation (starts 4 days after injury, lasts 2-3 weeks) -> epithelialization, angiogenesis, fibroplasia (granulation tissue)
- Maturation (starts 17-20 days after injury)
What are the 3 possible timings of wound closure and their indications
- Primary closure: for clean fresh wounds, contaminated wounds, or infected wounds that can be excised completely
- Delayed primary closure (2-5 days after injury): for contaminated wounds or large wounds with questionable viability (closed when viable granulation tissue is present)
- Secondary closure (5 or more days after injury): for dirty wounds or very extensive wounds with severe necrosis
(- Second intention healing: no closure)
Name some contra-indications to negative pressure wound therapy
- Coagulopathy
- Exposed vasculature, nerves, organs, fistula
- Malignancy in the wound
- Necrotic tissue with eschar
- Untreated osteomyelitis
What are some indications for antibiotic therapy for wounds
- Obvious local or systemic signs of infection
- Wound older then 6 hours
- Deep wound (involving muscle, bone, tendon)
- Wounds likely to get infected (bite wounds, penetrating wounds)
- When planning for a flap / graft
- Chronic non-healing wounds with infection confirmed by culture
- Immunocompromised patient
(Clean wounds less than 6 hours old or contaminated wounds that can be converted to clean and closed, or wounds that already have a mature healthy granulation tissue do not required antimicrobials)
What is the recommended empirical antimicrobial therapy for wounds based on severity
- Cefazolin for superficial wounds in stable patients
- Potentiated penicillins (Clavamox) for deeper or infected wounds
or ampicillin + fluoroquinolone /r aminoglycoside / 3rd gen cephalosporin for severe bite wounds
Antimicrobial therapy to be continued until granulation tissue covers the wound.
When is bacterial culture of a wound likely to be the most relevant
After a few days (2-5 days) on antibiotics if the wound is not healing or the patient’s condition is worsening
(Initial culture usually does not indicate what bacteria are going to cause an infection)
What topical antimicrobial is preferred for burn wounds
Silver sulfadiazine (but studies showed that honey is actually better)
What are causes for delayed wound healing
- Infection
- Neoplasia
- Foreign body in wound
- Chemotherapy
- Radiation therapy
- Diabetes
- Hyperadrenocorticism or glucocorticoid administration
- Hypoproteinemia
- Liver disease
What are the burn degrees?
- 1st degree: superficial epidermis only
- 2nd degree: epidermis and superficial dermis
- 3rd degree: full thickness (entire epidermis and dermis)
- 4th degree: full thickness with extension to muscle, tendon and bone
Can take up to 3 days for burn to declare itself
How is the total surface body area (TBSA) burned estimated?
Rule of nines:
- Head and neck –> 9%
- Each forelimb –> 9%
- Each hind limb –> 18%
- Dorsal trunk –> 18%
- Ventral trunk –> 18%
> 20% of TBSA –> serious CV, metabolic and pulmonary derangements
> 50% of TBSA –> poor prognosis
What burn patients are most at risk of hypovolemia
Patients with more than 20% total body surface area that is burnt and/or second or third degree burns
What fluid rate is recommended in burn patients with significant burnt surface area
1-4 mL/kg * body weight (kg) * % total body surface area burnt during first 24h
What bacteria are most commonly associated with burn wound infections
Gram negative (Pseudomonas)
When is cold lavage recommended in burn patients? For how long?
30-min cold water lavage (water ~15°C ; must be > 3°C) if the burn injury was within 2 hours before presentation
When is second intention healing not recommended for burn wounds
Partial-thickness burns involving the deep dermis (deep 2nd degree) or full-thickness burns (3rd degree) due to long delay in healing
Strictly contra-indicated if in the axillary or inguinal region because wound contraction will cause restricted range of motion
What type of bandage can be used for debridement phase? For proliferation phase?
Debridement phase: wet-to-dry or dry-to-dry, potentially with honey as primary layer, followed by gauze sponges, a padded secondary layer, and a protective tertiary layer. Alginate dressings can also be used.
Proliferation phase: the primary layer needs to be non-adherent and semi-occlusive (to promote moisture). Hydrogel can be used.
What are the 3 zones of a burn
- Zone of necrosis: area directly in contact with the heat source, characterized by coagulative necrosis
- Zone of stasis: area of decreased perfusion and intense inflammation and edema
- Zone of hyperemia: maintains blood flow and viability
Is a surgical exploration always recommended for a gunshot wound to the abdomen? To the thorax?
Always explore the abdomen, the thorax can often be conservatively managed
What is the recommended volume for surgical lavage of a cavity
200-600 mL/kg
What bacteria other than S canis can lead to necrotizing fasciitis
- Staph pseudintermedius
- Pseudomonas aeruginosa
- E Coli
- Clostridium
- Pasteurella
Define anatomic and physiologic degloving injury
Anatomic degloving injury = wound where the skin has been physically removed from the underlying tissues (the skin flap might be attached or not)
Physiologic degloving injury = a section of the skin that has been avulsed from the underlying tissues and blood supply but is not physically separated from the adjacent viable skin (might take days to declare itself)
(When the energy of the force applied is stronger and underlying tissues such as bones, tendons, muscles are injured as well, it is a “shear injury”
If the injury is only partial thickness of the skin, it is an abrasion injury)
What are beneficial properties of honey for wound healing
- Anti-bacterial (due to low pH, hyperosmolarity, and low content in hydrogen peroxide)
- Anti-oxidant
- Anti-edematous
- Anti-inflammatory
What is the mechanism of resistance of methicillin-resistant staphylococci
Acquisition of the mecA gene which encodes a penicillin-binding protein (PBP2a) which has much lower affinity for beta-lactams
Name a few drugs known to possibly cause cutaneous drug reactions (with possible associated anaphylaxis and/or SIRS)
- Cephalosporins
- Penicillins
- Sulfonamides
- NSAIDs
Name 2 severe immune-mediated skin disease caused by administration of various drugs
- Erythema multiforme
- Toxic epidermal necrolysis
What are first line antimicrobials recommended for necrotizing fasciitis
Clindamycin + ampicillin + aminoglycoside
If concern for AKI, the aminoglycoside can be replaced by a 3rd generation cephalosporin or a carbapenem
What oral sedative drug can cause pupil dilation and should be avoided in patients with glaucoma?
Trazodone
What re prognostic indicators for proptosis?
Pupil size:
- Miotic – best
- Mid size – guarded
- Mydriatic – poor
Positive direct PLR – guarded / good
Medial rectus muscle avulsion – guarded
- 2 or more – poor
Corneal/scleral rupture – guarded to poor
Massive intraocular hemorrhage – poor
Optic nerve transection – poor
How does glaucoma lead to blindness?
↑ IOP compresses flow of nutrient and outflow of toxins
–> Retinal ischemia hypoxia
–> Cell death
–> Blindness
What disease can cause secondary glaucoma?
- Anterior lens luxation
- Neoplasia
- Severe uveitis
Briefly describe how to perform a tarsoraphy for management of a proptosis
- Under GA
- Lateral canthotomy
- Unroll and pull eyelids over globe with strabismus hooks
- 2-3 horizontal mattress sutures (4-0 to 6-0 prolene) through stents and use meibomian gland openings as landmarks
- Leave opening at medial canthus for medications
Recheck in 2 days after inflammation has subsided
Remove sutures in 14-21 days or earlier if issues
