Intercostal Thoracotomy

 Exposure of a defined region of the thorax

 Good to excellent access to structures in the immediate area of thoracotomy

 Access to structures not in the immediate area is limited

 Complications rare, as long as airtight watertight seal obtained

 Good exposure to heart base, mainstem bronchi, great vessels, structures in dorsal aspect of thorax

 Site may be 3rd to 10th intercostal space, right or left, depending on structures to be exposed (Table 1)

 Lateral thoracic radiographs may be helpful in determining site for thoracotomy

 Cranial abdominal structures can be exposed with a combination of intercostal thoracotomy and diaphragmatic incision

Approach

 Skin incision parallel to intercostal space from costovertebral junction to sternum

 Cutaneous trunci

 Latissimus dorsi incised across it muscle fibers parallel to the skin incision

 Intercostal spaces can easily be counted at this point. 5th rib is usually recognized because it marks the end of the muscular portion of the scalenus muscle and the beginning of the external abdominal oblique.

 Scalenus or external abdominal oblique incised

 Serratus ventralis is separated between muscle bellies. Some muscle attachment can be elevated from rib as necessary.

 Intercostal muscles incised in the middle of the intercostal space

 Avoid intercostal vessels and nerve

 Pleura is bluntly punctured and incised with scissors

 Positive pressure ventilation must be initiated once thorax is open (open pneumothorax)

 Incision may be extended ventrally past costo-chondral junction to internal thoracic artery and dorsally to tubercle of the rib

 Finochietto retractors used to spread ribs

Closure

 Intercostal thoracostomy tube placed (20 French for most dogs, 14 French for cats) through dorsocaudal thoracic wall caudal to the thoracotomy

 Heavy gauge sutures (0 or 1 PDS or Prolene) interrupted circumcostal sutures placed around the ribs cranial and caudal to incision

 Coordinate suture passage with ventilation to avoid trauma to lungs

 Avoid damage to intercostal vessels (caudal border of rib)

 Pre-place all sutures

 Helpful to have an assistant approximate incision with more dorsal suture while surgeon ties more ventral sutures

 Bupivacaine local blocks can be placed 2–3 ribs cranially and caudally at this point.

 Nerve sits along caudal border of rib. Remember to place block as dorsally as possible

 Muscle layers closed individually with simple continuous absorbable sutures of appropriate size

 Skin closed in standard fashion

 Each layer must be carefully closed to obtain an airtight/watertight seal

 Leave thoracostomy tube open to air until you are ready to evacuate chest to avoid a closed or a tension pneumothorax (open pneumothorax okay with ventilation)

 Drain air from chest until negative pressure obtained

Rib Resection Thoracotomy

 2 minor advantages over intercostal:

 Somewhat increased exposure

 Potentially fewer adhesions

 However:

 Increased time necessary to complete the approach

 Less secure closure

 Approach the same as intercostal for exposure of the thoracic wall

 Periosteum of rib to be excised is elevated from the midlateral surface

 Rib excised with micro-sagittal saw or bone cutter

 Variation is the "Rib Pivot" which relies on the costo-chondral junction. Dorsal aspect of rib transected and rib (or multiple ribs) is pivoted out of the surgery area, rather than be excised. Useful for removal of large masses from thoracic cavity.

 Closure accomplished with interrupted mattress sutures preplaced in medial and lateral edges of incised periosteum for rib resection. Closure for rib pivot is by interrupted heavy gauge suture place through pre-drilled holes above and below cut.

Median Sternotomy

 Only approach that provides access to entire thoracic cavity. Usually approach of choice for exploratory thoracotomy.

 Association with excessive morbidity is unjustified

 Can be extended with midline laparotomy to explore both thorax and abdomen or into the cervical region by combining with a ventral cervical approach

 Access to structures in dorsal aspect of thorax (great vessels, hilus of bronchi, thoracic duct is more difficult, but not impossible in large chested dogs with this approach

 Skin and subcutaneous tissues incised along ventral midline over the sternum

 Pectoral musculature is elevated to expose midline of sternum

 Midline sternotomy performed with oscillating saw. Avoid trauma to intrathoracic structures. Avoid internal thoracic arteries proximally.

 Leave either manubrium or xiphoid intact to add approximation and closure. Manubrium difficult to incise with saw, bone snips or Mayo scissors useful.

Closure:

 Thoracostomy tube placed from a subcostral position lateral to midline OR through a small hole in diaphragm just dorsal to manubrium (easier)

 Stable closure important to avoid post-operative pain. Heavy gauge monofilament suture or orthopedic wire is placed around each sternabrae in a figure 8 pattern.

 One study suggests monofilament suture less stable than wire closure in large dogs leading to delayed healing and increased pain (Vet Surg 1999;28:402)

Trans-Sternal Thoracotomy

 Exposure obtained with intracostal thoracotomy can be dramatically increased by continuing past costo-chondral junction, across sternum, and connecting with intracostal thoracotomy on opposite side

 Indicated when extensive exposure of a specific region is needed

 Few indications and rarely used in small animals

 Extend intercostal thoracotomies to the sternum after ligation of the internal thoracic arteries. Intercostal incisions are then joined by a transverse osteotomy through the sternebra.

 Positioned in dorsal recovery

 Sternum re-apposed with pins and cerclage wire. Intercostal thoracotomies closed as previous described.

Post-Operative

 Immediate post-operative period is the most critical

 Monitor for pneumothorax, hemothorax, pulmonary edema. Circulatory shock, hypoventilation (usually pain related), hypothermia, acid-base disorders all possible following thoracic surgery.

 Always place a thoracostomy tube during surgery

 Leave tube open to atmosphere during closure to avoid a tension pneumothorax

 Evacuate the pleural space until negative pressure occurs. Check at least every 20 minutes or sooner if needed.

 Maintain thoracostomy tube until a minimum of two negative aspirations 20 minutes apart

 If pneumothorax or pleural effusion persists, maintain with continuous pleural draining (Pleur-evac).

 Thoracostomy tubes should never be left unattended. They are potentially dangerous.

 Hemothorax can be treated by combination of IV fluids, blood transfusions (packed cells, whole blood, autotransfusion if no neoplasia). If severe, a return to surgery to identify and ligate the source is indicated.

 Ventilation commonly depressed by anesthetic drugs, post-operative hemo or pneumothorax, restrictive thoracic bandages, and pain

 PaCO₂ > 50 mm Hg

 Decreased tidal volumes (< 10 ml/kg)

 Impaired gas exchange due to collapsed alveoli, V/Q mismatch

 O₂ therapy may be indicated

 Ventilatory support is rarely necessary

 Maintaining 5 cm H₂O PEEP during surgery significantly decreases the degree of hypoxemia secondary to alveolar collapse

 Hypovolemia, hypothermia, myocardial depression are the most common causes of post-operative circulatory disorders. Residual anesthetic drugs should be easily avoided with modern anesthetics (ketamine, propofol, isoflurane, sevoflurane, fentanyl, etc.) Avoid thiobarbiurates and fat soluble anesthetics.

Analgesia is Indicated in ALL Patients

 Local block during closure (do not exceed 5 mg/kg)

 Intra-thoracic lavage of local anesthetic or opioids via thoracostomy tube (6–12 hours duration, easy)

 Blocks spinal nerve roots

 Administer in dorsal recumbency

 1.5 mg/kg

 Painful: Should be done under anesthesia, or use Lidocaine (1 mg/kg) first

 Parenteral opioids effective but risk respiratory depression

 Fentanyl infusion: rapid, titratable, short acting