104. Thorax Flashcards
approaches to the thorax
- lateral thoracotomy2. median sternotomy3, transdiaphragmatic4. MI—thoracoscopic (lateral, subxiphoid, transxiphoid)5. transsternal thoracotomy by connecting two lateral thoracotomies
what travels through the thoracic inlet
- trachea2. esophagus3. nerves: phrenic, vagus, recurrent laryngeal4. great arteries and veins
insertion point of two muscular crura of diaphragm
lumbar 4th vertebral bodies
blood supply and innervation to the thoracic cavity
intercostal arteries (aorta, internal thoracic artery)intercostal veins (azygous)intercostal nervesall sit caudal to each rib
artery that supplies the sub scapular area of the outer thoracic skin and latissimus dorsi
thoracodorsal artery (branch from sub scapular artery)
how many ribs and sterner are there
13 T vertebra (ribs 1-9 articulate)13 ribs9 sternebra
Origin and insertion of latissimus muscle
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
landmark of scalenus muscle insertion
5th rib
if unsure where to make a lateral thoracotomy, what guideline should you use
aim more caudal bc it is easier to retract ribs craniallys
when entering a lateral thoracotomy, caution with what vessels dorsal and ventrally
dorsal: branches of aorta—intercostal artery branchesventral: internal thoracic arteries (do not extend ventral incision beyond the lateral aspect of the transverse thoracic muscle
two ways to close a thoracotomy
–circumcostal (do not pull to tight may entrap nerves, may fracture ribs)–transcostal (may avoid nerves but only done in big dogs)
why is a rib resection indicated
–removal of thoracic wall tumor with margins –increased exposure–removal of larger tumors in the thoracic cavityligate intercostal artery above and below transection
methods to ensure stability of median sternotomy closure
–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
T/Fair embolism is common with median sternotomy
trueair embolism is common with median sternotomy and small air bubbles are often seen within the internal thoracic veins after the thorax is opened
what does the diaphragm look like when negative pressure ir not in the chest vs when residual air is in there
normal negative pressure restored: concaveresidual air present: billowing
feline predisposition for pectus excavatum
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
known complications of median sternotomy
sternal osteomyeltitismay need to remove implants
thoracic radiographs following trauma is necessary to rule out what?
—diaphragmatic hernia–rib fractures–pneumothorax–flail chest–pulmonary contusions (may take up to 72 hrs to see)–pulmonary lacerations
what does the presence of a “step” sign on thoracic focused assessment with sonography for trauma indicate
discontinuity of the parietal pleural surface signifies an intercostal muscle tear or rib fracturecan also evaluate for fluid on T-FAST
T/F no significant difference in outcome was seen btwn stabilized and unstabilized flail chest patients
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
MST of thoracic wall tumors OSA and chrondrosarcoma after surgical resection
OSA 17 weekschondrosarcoma 250 weeks
diagnostic approach to thoracic lung tumors
–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)
margins recommended for thoracic wall tumor excision
3 cm or more–usually includes one Unaffected rib cranial and caudal to lesion
main goals of thoracic wall reconstruction
—restore integrity of pleural space so negative P can be achieved–ensure rigidity of thoracic wall–ensure adequate epithelial coverage
how many ribs can safely be removed for rib resection
4-6 ribs
muscles used as flaps to close the thoracic wall defects
–latissimus dorsi (bipedicle or cut at origin and used as rotational)–diaphragm advancement (caudal defects)–transversus abdominis–external abdominal oblique–deep pectoral
commercial products available for thoracic wall reconstruction
—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
what methods can be used to re-establish the normal concavity of the thorax and help assist closure with extensive rib resection
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)
