Trans thoracic exposure

The chest wall has two muscular layers. The outer layer is made by the trapezius and Lattisimus dorsi muscle. Deep to this layer lies the Serratus Anterior and Rhomboid muscles, which cover the ribs, and the intercostal muscles. The internal and external intercostals span the intercostal space. The neuro vascular bundle lies in the inferior aspect of the rib, in the intercostal groove. The superior most structure is vein, then there is the intercostal artery and most caudally there is intercostal nerve. The parietal pleura lies deep to the intercostal muscles and the visceral pleura envelopes the Lung. The sympathetic chain lie anterior to the transverse process, the greater splanchic nerve arises from the sympathetic chain in the mid thoracic region and enters the abdomen piercing the diaphragm. The segmental vessels lie directly over the vertebral column posterior to the sympathetic chain and continues as the intercostal vessels

Exposure:

Incision: An incision is made over rib of the corresponding vertebrae. The ribs can be counted from above downwards or vice versa. While counting from up it must be remembered that the first rib appears inside the second and is difficult to trace.

The skin and sub cutaneous tissue is opened over the rib and the muscles are cut using an electro cautery to achieve hemostasis. The rib is dissected sub periosteally using a periosteal elevator. The intercostals nerves present inferior to rib should be preserved. The rib can then be disarticulated from the transverse process of the corresponding vertebrae or it can be cut at point between the costotransverse joint and angle of the rib. The rib may be preserved for later use as bone graft. The bone wax applied at ends helps to control bleeding. The Parietal pleura can be seen below the rib bed after the inner periosteum is opened. The parietal pleura can be opened and reflected off spine, the lungs can be retracted medially with retractors. Ocassionally adhesions present between the pleura and lung may need to be bluntly dissected with a finger. The retraction of lung should be left off every half hour so as to allow the lung expansion and prevent postoperative atelectasis.

The parietal pleura covers the spine and surrounding structures and can be opened with help of scissors, after this it can be reflected off the vertebral bodies and discs using a sponge.

The disc, the intercostals artery and the vein can be identified at this point. The intercostals vessels can be isolated, and cut between the ligatures. It is preferable to tie and cut these vessels a little away from aorta so as to avoid the injury to aorta while clamping the vessels.

The periosteal elevator is then used to elevate the soft tissue and expose the disc and the vertebral body. If the access to the posterior disc space and spinal canal is inadequate, the rib head can be resected to increase the exposure.

Before closing it is important to ensure that entire lung is fully expanded. The parietal pleura should be closed over the spine. The chest is closed over a chest tube. The ribs may be approximated using a strong non-absorbable suture like Dacron.

Potential Complications:

Injury to intercostals vessels.

Lung contusion/ injury.

Injury to azygos vein.

Injury to Aorta.

Uncontrolled Hemorrhage from segmental vessels.

Postoperative Lung atelectasis.

Pneumothorax.

Injury to thoracic duct/ chylothorax.

Injury to long thoracic nerve.

Infection.