Exam 2 Flashcards
What are the primary sources of blood for skin flaps?
The deep cutaneous artery and vein (big vessels that supply a wide area) which then branch into the deep/subdermal plexus
-provided by the skeletal musculature and panniculus muscles respectively
What are some important things to consider when handling the skin?
-extremely gentle handling
-avoid grasping skin at the reconstructive sites with thumb forceps
-use skin hooks or stay sutures to allow for gentle tissue handling
Where on a skin flap is the blood supply the most compromised?
At the tip (farthest away from blood supply)
- must be extremely delicate if using the tip of the tissue to move the flap- can use the subQ tissue to grab rather than the top of the skin
T/F: The incision always needs to be perpendicular to the tension lines
False. It needs to be parallel to the tension lines
- allows you to close with the least amount of tension
Are skin sutures ever for tension reduction?
NOO- just there to achieve nice apposition of the skin edges
Describe the concept of mechanical creep.
Mechanical creep is what happens when skin is under load for a period of time
- as stress is placed on skin, skin can release its own tension
-tension reduction and stress relaxation can be used in the OR to release tension on tissues
Where is the highest amount of tension in an incision?
At the midline
Describe biological creep
Stretching of the skin naturally over time due to pregnancy
What are the optional conditions for the wound environment?
-wound itself should have no infection and good blood supply
-the area surrounding the wound should have minimal inflammation and necrosis
What are the primary wound factors you need to consider when deciding how to close? What about patient specific factors? Owner factors?
Wound factors: size and shape of the wound, anatomic location
Patient factors: must consider species and breed, age, temperament and comorbidities
Owner factors: financial considerations, compliance
Describe the process of undermining the skin
-separate the skin from the underlying tissue
-preserve the subdermal plexus by cutting deep to the cutaneous trunci/platysa/sphincter colli muscles
-if in an area that you cannot see the above muscles, cut to the underlying muscle fascia
In what situation do you want to avoid undermining?
When resecting tumors
If placing sutures to stretch the skin, what 2 things can help to avoid damage to the patient?
Placing foam underneath the sutures so they don’t cut the underlying tissue
- placing the tissues a bit off of the tissue edge so they don’t rip out
What are the 4 examples we discussed in class of tension relieving sutures?
Cruciate sutures, far-near-near-far, and far-far-near-near, mattress sutures
What is important to consider when using walking sutures?
Don’t place too many as they can compromise the blood supply!
-make bites parallel to the direction of pull
-take strong bites of the dermis but do not penetrate the skin
How can bolsters be used for tension reduction?
You place then under vertical mattress sutures to reduce tension on the skin itself and instead put the tension over another material
What are the two different techniques for relaxing incisions?
- Single relaxing incision (bipedicle flap)
- Mesh relaxing incision (1 cm incisions inrows spaced 1 cm apart)
What is the main worry when using a mesh relaxing incision?
There is a chance that you may devitalize the skin
- therefore it is very important to be judicious with this technique
What are the main considerations when using subdermal plexus flaps?
- maintain appropriate base (larger than width of flap) in order to preserve the blood supply as much as possible
-the length needs to be sufficient to cover the defect
What are the main differences between single pedicle flaps and bipedicle flaps?
-with single pedicle flaps there are 2 skin incisions made equal in length to the defect
-with bipedicle flaps the incisions are made parallel to the long axis of the defect, and the flap length should be no more than 2X the length of the flap base
When would you use subdermal plexus rotation flaps?
In situations where there is not loose skin immediately surrounding the defect, but the skin is looser a bit more proximal or distal to the defect
T/F: With transposition flaps, the width of the flap has to equal the width of the defect
TRUE
-these flaps are performed in which one border of the flap is adjacent to the defect, and then the skin is rotated
In what areas are skin fold flaps commonly used?
Flank fold flaps and elbow fold flaps to cover defects on upper limbs
With axial pattern flaps, where does the blood supply come from?
The direct cutaneous artery and vein
-can be longer relative to the pedicle
-can be rotated up to 180 degrees at the base
-overall survival rate: 87-100%
-need to know anatomy of the vessels
What is the difference between peninsula and island flaps?
Peninsula flaps have intact skin at base vs island flaps have no connection to surrounding skin
What are the 4 processes that allow free skin grafts to survive?
Adherence: fibrin strands –> fibrous adhesions
Plasmacytic imbibition
Inosculation
Vascular ingrowth/revascularizarion
What type of free skin graft has the most ideal characteristics for survival?
A: split thickness unmeshed grafts
B: Full thickness unmeshed grafts
C: full thickness mesh grafts
D: split thickness mesh grafts
D
What are the main post-op complications of reconstruction surgery?
-necrosis
-dehiscence
-seroma
-infection
What are the main factors that contribute to reconstruction complications?
-compromised blood supply
-excessive tension
-excessive motion
-cold
What is the cutoff for acute vs chronic diaphragmatic hernias?
Acute is less than 14 days, chronic is greater than 14 days
What are the 2 different types of congenital diaphragmatic hernias?
- pleuroperitoneal and peritoneopericardial
If the diaphragm tears, is it more likely to be at the muscular or tendinous portion?
The muscular portion
Name the foramen in the diagram from ventral to dorsal?
Caval foramen, esophageal hiatus, aortic hiatus
What travels through the esophageal hiatus?
The esophagus (of course) and the vagus nerve
What is the difference between a circumferential tear, radial tear and combined tear of the diaphragm?
A circumferential tear occurs parallel to the body wall, a radial tear occurs perpendicular to the body wall and a combined tear occurs in multiple directions
What is the most common source of trauma that would cause a diaphragmatic tear?
Motor vehicle accidents
-may also see pulmonary contusions and rib fractures
-must do basic stabilization before focusing on the most ugly lesions
What can cause iatrogenic diaphragmatic tears?
Too long of an incision for abdominal exploratory, or being too enthusiastic when clearing falciform fat
-could also be from thoracocentesis
How does indirect injury cause diaphragmatic tears?
A acute increase in intraabdominal pressure can cause a diaphragmatic costal muscle rupture
What is one of the most concerning sequele to diaphragmatic tears?
Organ herniation
Rank the likelihood of the following organs to herniate through the abdomen from most likely to least likely:
1. Uterus
2. Omentum
3. Spleen
4. Liver
5. Colon
6. Stomach
7. Small intestine
8. Pancreas
Liver, small intestine, stomach, spleen, omentum, pancreas, colon, uterus
What are the main clinical signs associated with diaphragmatic hernias?
Dyspnea (most common), hypovolemic shock due to cardiopulmonary decompensation (in trauma patients), GI signs, Lethargy, difficulty lying down
T/F: You should rule out a diaphragmatic hernia if there is no history of acute trauma
NO
What are some of the complications associated with diaphragmatic tears?
- pneumothorax, hemothorax, pleural effusion
-herniated viscera, possible strangulation
-pulmonary and caval compression
-chest wall contusions, flail chest
Why are the veins the first to be affected by compressive effects after herniations?
They are thin walled and compress easily
What to you expect to hear/see/feel on your physical exam?
-Muffled heart and lung sounds (displaced heart sounds)
-Thoracic borborygmi (not reliable)
-Tucked up abdomen (in the case of chronic hernias)
-can have a normal physical exam
Which diagnostics are the most useful and readily available imaging diagnostics for diaphragmatic hernias?
Thoracic radiographs and abdominal ultrasound
Which view is most helpful for diagnosing diaphragmatic hernias via radiographs?
Lateral views
- can see loss of normal diaphragmatic outline in 66-97% of cases
-abdominal viscera in thorax is diagnostic
-obscured or displaced cardiac shadow
-excessively displaced cranial pylorus/duodenum
When does ultrasound become very helpful in cases of diaphragmatic hernias?
When there is concurrent pleural effusion
-can diagnose diaphragmatic hernias with 93% accuracy
T/F: CT scan is often indicated in diaphragmatic hernia cases
False- rarely indicated
- can be helpful in polytrauma cases
What are the treatment options for diaphragmatic hernias?
Surgery
-preop management critical- need to be stable (treat shock, provide analgesia, provide o2 supplementation, thoracocentesis or gastric decompression if indicated)
Describe some primary anesthetic considerations in the case of diaphragmatic hernias
-poor ventilation (viscera and fluid in thorax, pulmonary compression, lack of functional diaphragm)
-poor gas exchange (pulmonary contusions, V/Q mismatch)
-poor perfusion (shock, caval compression)
When should you do surgery in cases of diaphragmatic hernias?
- as soon as possible: when patient is stable and can tolerate anesthesia
-however, patient stability is critical!
-must take the time to improve the patients anesthetic status if at all possible
What are the 3 reasons you should not stabilize before surgery in diaphragmatic hernia cases?
-resistant deterioration of the patient despite appropriate management (must be realistic with the owners)
-gastric herniation with tympany (stomach accumulating with air in thoracic cavity)
-persistent abdominal pain (intestinal strangulation)
What are some anesthesia factors that can improve patient odds in diaphragmatic hernia cases?
-table tilt to elevate head and thorax
-preoxygenate
-rapid smooth induction
-rapid intubation
-avoid high inspiratory pressures (>20 cm H20) to avoid reinflation injury
Describe the surgical approach in diaphragmatic hernia cases
-abdominal and thoracic prep (median sternotomy, lateral thoracic prep for thoracostomy tube)
-ventral midline celiotomy common approach in all cases, but be prepared to extend into sternotomy
-reduce the hernia with gentle traction and be prepared to enlarge the defect
-evaluate viability of herniated organs
-place thoracostomy tube through the lateral thorax or abdomen for PRN thoracic evaluation
-debridement of defect edges (controversial)
-use absorbable monofilament with a simple continuous pattern (use caution when suturing around critical structures)
What unique considerations come with a chronic diaphragmatic hernia?
Mature adhesions, fibrosis, reperfusion injury, re-expansion pulmonary edema, loss of domain, primary apposition not possible