14. thoracic surgery 2 - pleural space & lung disease

clinical signs of acute vs. chronic pleural effusion

• acute: tachypnea, dyspnea, collapse, cyanosis

• chronic: lethargy, exercise intolerance, inappetance, weight loss (nonspecific)

pleural effusion — physical exam findings

• restrictive ventilatory pattern (limited inspiration)

• diminished heart / lung sounds

• dyspnea

• tachypnea

• elbows abducted / neck extended

pleural effusion — diagnostics

• radiographs

  • loss of fine detail; fissure lines (indicate fluid); masses; cardiac/pulmonary disease

• U/S

  • look for fluid/air, cardiac, mediastinal masses, thoracocentesis

  • FAST scan

    • can see fluid easily

    • loss of glide sign with air

• CT scan

  • masses, metastases, lung lobe torsion, bullae, foreign bodies

• thoacocentesis

  • sample in EDTA and clot tubes

  • sterile sample for culture

  • cell counts, sp. grav, total protein, triglycerides, cholesterol

thoracocentesis technique

• sternal recumbency (except pneumothorax — air rises; may do in dorsal)

• ventral; 5-8th rib spaces

• aseptic preparation

• insert at oblique angle to minimize damage to lungs

• use tubing to connect hub to stopcock

  • can continuously drain without having to detach the syringe

  • can also use a one-way valve

types of pleural effusion

• fluid

  • transudate

    • CHF, hypoproteinemia (not surgical diseases)

  • modified transudate

    • lung lobe torsion, diaphragmatic hernia, neoplasia, chylothorax

  • exudate

    • non-septic — diaphragmatic hernia, neoplasia, chronic chylothorax, FIP, lung lobe torsion, hemorrhage

    • septic — pyothorax secondary to trauma, tracheal or esophageal rupture, foreign body, iatrogenic, extension from pulmonary disease

• air (pneumothorax)

causes & clinical signs of pyothorax

causes

• penetrating trauma (including bite wounds)

• migrating grass awn / foxtail (hunting & other sporting dogs) and other foreign material

• esophageal or tracheal disease / trauma

potential clinical signs

• tachypnea, coughing, fever, etc.

• may be nonspecific — weight loss, lethargy, exercise intolerance

pyothorax diagnosis

• thoracocentesis → cytology / culture

• aerobes most common

  • gram (-): e. coli, pasteurella, etc.

  • gram (+) rods: actinomyces, nocardia

    • sulfur granules may be apparent in fluid removed

  • gram (+) cocci: staph/strep spp.

• anaerobes common too (cats > dogs)

pyothorax treatment — conservative approach

• drainage (bilateral thoacostomy tubes), pleural lavage, broad-spectrum antibiotics (aerobic + anaerobic) while awaiting culture

  • adjust antibiotics based on culture

  • often continued for ~4wks

• CT and surgery for cases refractory to medical management

advantages / disadvantages of conservative pyothorax treatment

• advantage: clears infection and may make nidus more obvious on imaging

• disadvantages: may prolong the inevitable and lead to more chronic / fibrous changes

pyothorax treatment — (more) aggressive approach

• CT & surgery at time of diagnosis

• advantage: potential to correct sooner

• disadvantage: potentially harder to find nidus and may not actually be needed for every case

**appropriate time for surgical intervention remains controversial

causes of chylothorax

• anything impeding flow of chyle from thoracic duct to cranial vena cava

  • heart disease, cancer, trauma, fungal disease, heartworms, lung lobe torsion, etc…

• underlying cause rarely found

  • idiopathic common in afghan hounds

chylothorax diagnostics

• thoracic radiographs

• thoracocentesis

  • cytology — large amounts of lymphocytes + some macrophages

  • fluid triglycerides higher than serum

  • culture fluid

• CT scan

• contrast lymphangiography

• cardiac workup

• heartworm testing

idiopathic chylothorax — conservative management

• low response rates reported

• low-fat diet

• benzopyrones (rutin): nutraceutical that stimulates macrophage removal of fat — similarly ineffective

• octreotide: somatostatin analog — ↓ thoracic duct flow?

• corticosteroids

• periodic thoracocentesis or pleuralport (palliative / salvage option)

what is a consequence of prolonged chylothorax?

• constricting fibrosing pleuritis

• happens even faster in cats than in dogs

• idiopathic disease should be treated with surgery preferentially → don’t wait too long if doing conservative management

surgical techniques for idiopathic chylothorax

• thoracic duct ligation (TDL) — 50-60% success rate alone

  • failures due to multiple lymphatics or recanalization

  • purpose: shut down flow of chyle from abdomen into thoracic cavity

• cisterna chyli ablation (CCA) — 83-87% success in combo with TDL

  • following ablation, lymphatic vessels form anastomoses with venous system

• pericardectomy — 80% success with TDL

• pleurodesis (obliterates pleural space) — ineffective

causes of hemothorax

• trauma

• neoplasia

• lung lobe torsion

• coagulopathy

hemothorax diagnostics

• thoracocentesis

• coagulation panel / platelets

• CT scan

hemothorax treatment

• for trauma — attempt to manage conservatively

• tumors — stabilize first, then surgery

• blood type and transfuse if needed

causes of pneumothorax

• trauma

  • blunt force

  • penetrating

• spontaneous

  • neoplasia

  • infectious disease

  • pulmonary bullae (siberian huskies over-represented)

• CT scan helpful in diagnosis of underlying cause

pneumothorax — medical management

• ~50% success reported

• thoracocentesis

• thoracostomy tube with:

  • intermittent drainage

  • continuous suction

• autologous blood patch pleurodesis

  • stop suctioning long enough for a seal to form

• recurrence likely with bullous lung disease

pneumothorax — surgical treatment

• 85% success reported

• ideal when lesion identified on CT & especially if non-responsive to continuous suction

• results in lower recurrence, decreased mortality and hospitalization times

• remove affected lung parenchyma

• recurrence possible, but less common

indications for lung lobectomy

• obtain biopsy

• treat disease

  • cysts

  • abscesses

  • tumors

  • bullae

  • trauma

  • lung lobe torsion