104. Thorax

Question 1

approaches to the thorax

Answer 1

1. lateral thoracotomy2. median sternotomy3, transdiaphragmatic4. MI—thoracoscopic (lateral, subxiphoid, transxiphoid)5. transsternal thoracotomy by connecting two lateral thoracotomies

Question 2

what travels through the thoracic inlet

Answer 2

1. trachea2. esophagus3. nerves: phrenic, vagus, recurrent laryngeal4. great arteries and veins

Question 3

insertion point of two muscular crura of diaphragm

Answer 3

lumbar 4th vertebral bodies

Question 4

blood supply and innervation to the thoracic cavity

Answer 4

intercostal arteries (aorta, internal thoracic artery)intercostal veins (azygous)intercostal nervesall sit caudal to each rib

Question 5

artery that supplies the sub scapular area of the outer thoracic skin and latissimus dorsi

Answer 5

thoracodorsal artery (branch from sub scapular artery)

Question 6

how many ribs and sterner are there

Answer 6

13 T vertebra (ribs 1-9 articulate)13 ribs9 sternebra

Question 7

Origin and insertion of latissimus muscle

Answer 7

O: lumbobodorsal fascia and TL vertebraI: proximal humersuaction: draws scapula and forelimb caudallybipedicle, myocutaneous or transposition flap can be made and used to cover large defectstype V muscle

Question 8

landmark of scalenus muscle insertion

Answer 8

5th rib

Question 9

if unsure where to make a lateral thoracotomy, what guideline should you use

Answer 9

aim more caudal bc it is easier to retract ribs craniallys

Question 10

when entering a lateral thoracotomy, caution with what vessels dorsal and ventrally

Answer 10

dorsal: branches of aorta—intercostal artery branchesventral: internal thoracic arteries (do not extend ventral incision beyond the lateral aspect of the transverse thoracic muscle

Question 11

two ways to close a thoracotomy

Answer 11

–circumcostal (do not pull to tight may entrap nerves, may fracture ribs)–transcostal (may avoid nerves but only done in big dogs)

Question 12

why is a rib resection indicated

Answer 12

–removal of thoracic wall tumor with margins –increased exposure–removal of larger tumors in the thoracic cavityligate intercostal artery above and below transection

Question 13

methods to ensure stability of median sternotomy closure

Answer 13

–make sure to cut sterner on midline—leave either manubrium and/or xiphoid intact–figure 8 wire closure across sternebra with stainless steel wire (superior than double loop) incorporating the costosternal junction–alternate figure 8 every other sternebra

Question 14

T/Fair embolism is common with median sternotomy

Answer 14

trueair embolism is common with median sternotomy and small air bubbles are often seen within the internal thoracic veins after the thorax is opened

Question 15

what does the diaphragm look like when negative pressure ir not in the chest vs when residual air is in there

Answer 15

normal negative pressure restored: concaveresidual air present: billowing

Question 16

feline predisposition for pectus excavatum

Answer 16

burmese catsventral external splint (vet cuttable plate, thermoplastic splint) 2-4 weeks (sutures passed around each sternebra)caution reexpansion pulmonary edema if initial severe lung compression

Question 17

known complications of median sternotomy

Answer 17

sternal osteomyeltitismay need to remove implants

Question 18

thoracic radiographs following trauma is necessary to rule out what?

Answer 18

—diaphragmatic hernia–rib fractures–pneumothorax–flail chest–pulmonary contusions (may take up to 72 hrs to see)–pulmonary lacerations

Question 19

what does the presence of a “step” sign on thoracic focused assessment with sonography for trauma indicate

Answer 19

discontinuity of the parietal pleural surface signifies an intercostal muscle tear or rib fracturecan also evaluate for fluid on T-FAST

Question 20

T/F no significant difference in outcome was seen btwn stabilized and unstabilized flail chest patients

Answer 20

TRUE (Olsen, Renberg et al JAAHA 2002)current thought is that respiratory problems is more likely related to underlying pulmonary trauma rather than the presence of a flail segmentexternal splint 2-4 weeks

Question 21

MST of thoracic wall tumors OSA and chrondrosarcoma after surgical resection

Answer 21

OSA 17 weekschondrosarcoma 250 weeks

Question 22

diagnostic approach to thoracic lung tumors

Answer 22

–full PE, ortho, neuro–thoracocentesis if fluid (diagnostic and therapeutic) for cytology +/- culture–thoracic rads–US (consistency of mass and if it moves with T wall or independently indicating pulmonary tumor) +/- needle aspirate of biopsy (cytology, impression smears, histo)–CT/MRI–Biopsy (keep biopsy site in surgical field or plane for radiation therapy)

Question 23

margins recommended for thoracic wall tumor excision

Answer 23

3 cm or more–usually includes one Unaffected rib cranial and caudal to lesion

Question 24

main goals of thoracic wall reconstruction

Answer 24

—restore integrity of pleural space so negative P can be achieved–ensure rigidity of thoracic wall–ensure adequate epithelial coverage

Question 25

how many ribs can safely be removed for rib resection

Answer 25

4-6 ribs

Question 26

muscles used as flaps to close the thoracic wall defects

Answer 26

–latissimus dorsi (bipedicle or cut at origin and used as rotational)–diaphragm advancement (caudal defects)–transversus abdominis–external abdominal oblique–deep pectoral

Question 27

commercial products available for thoracic wall reconstruction

Answer 27

—prosthetic polypropylene mesh (Marlex, Prolene Mesh)–prosthetic polytetrafluoroethylene (PTFE–GoreTex)–biological grafts (porcine SIS): decr adhesions to meshprosthetics may be associated with persistent post implant wound infection/fistula from adhesions (polypropylene mesh 0-6%); prevent with addition of muscle, omentum, or vascularized tissueunderlay

Question 28

what methods can be used to re-establish the normal concavity of the thorax and help assist closure with extensive rib resection

Answer 28

Lubra or veterinary cuttable plates for ribs (attached proximally and distally) in addition to synthetic material or autogenous tissue+/- drains (keep drain sites near surgical field if re-excision or radiation needed post op)