Question 6

How must this life threatening status then be treated?

Chest tube decompression.

The condition shown in this chest radiograph in p.a. projection can become life threatening. Please indicate the correct term for life threatening status and describe briefly what happens in addition to the fact that air has entered the pleural space!

Tension pneumothorax. The pressure differential between the left and right sides of the pleura cause the mediastinum to be pulled to the right thus compressing the structures of the heart thus limiting the functions of the heart.

Please name 3 characteristic findings on a chest radiograph which are associated with this condition.

The affected side has pleural space filled with air, which appears black on the radiograph. Collapse of the lung leaves wide space between visceral and parietal pleura. There is no lateral pulmonary vessels beyond the visceral pleura on the effected side.

1. Contrast the line of surface projection of the inferior margin of the lung with that of the inferior margin of the parietal pleura during quiet respiration, relative to the ribs, at the midclavicular line, midaxillary line, and the paravertebral line.

a. During quiet respiration, the inferior margin of the lung remains about two ribs higher than the inferior margin of the parietal pleura. At the midclavicular line, the inferior margin of the lung is at the 6th rib, while the inferior margin of the parietal pleura is at the 8th rib. At the midaxillary line, the inferior margin of the lung is at the 8th rib, while the inferior margin of the parietal pleura is at the 10th rib. At the paravertebral line, the inferior margin of the lung is at the 10th rib, while the inferior margin of the parietal pleura is at the 12th rib.

1. List, in order, the layers of the thoracic wall through which a tube would be passed (in the fifth intercostal space in the midaxillary line) in order to access the pleural cavity (beginning with skin and including fascia).

a. Layers: skin → superficial fascia → deep fascia → external intercostal muscle → internal intercostal muscle → innermost intercostal muscle → endothoracic fascia (suprapleural membrane) → parietal pleura → pleural cavity

1. What is the anterior extent of the right pleural cavity? of the left pleural cavity?

a. The anterior extent of the right pleural cavity is where the costal and mediastinal surfaces of parietal pleural meet anteriorly and overlap the heart. The same is true of the left pleural cavity, except that the cardiac notch indents this border of the left lung.

1. What are the external and internal intercostal membranes?

a. The external intercostal membrane is the anterior continuation of the external intercostal muscle. The internal intercostal membrane is the posterior continuation of the internal intercostal muscle.

1. Explain why the tube is inserted near the upper border of the rib.

a. The neurovascular bundle travels in the intercostal grooves on the inferior side of the respective rib. In order to avoid hitting the nerves and vessels, the tube is inserted on the inferior margin of an intercostal space on the superior border of a rib.

1. Describe the pleura; consider visceral and parietal pleurae and the costal, diaphragmatic, mediastinal, and cervical parts of the parietal pleura.

a. The pleurae is a serous sac consisting of two continuous membranes that cover the lungs and line the pulmonary cavity. The visceral pleura is the inner lining, which directly adheres to and covers the lungs. The parietal pleura is the outer lining which lines the pulmonary cavity. b. The costal part of the parietal pleura lines the inner surface of the thoracic wall and ribs. The diaphragmatic part is the inferior most portion and lines the diaphragm. The mediastinal part lines the mediastinum. The cervical part is the superior most portion and extends into the neck.

1. Define "pleural cavity".

a. The pleural cavity is the potential space between visceral and parietal pleura, which is filled with a capillary layer of serous pleural fluid that lubricates and enables the pleura to slide against one another during respiration.

1. What are the costomediastinal and costodiaphragmatic recesses and why are they important?

a. The pleural recesses exist due to the lungs only fully occupying the pulmonary cavities upon deep inspiration. This allows for a recess that permits the lungs to have a phase of deep inspiration. The costomediastinal recesses is the potential space at the border of the costal and mediastinal pleura. The costodiaphragmatic recess is the potential space in the posteroinferior portion of the pleural cavity.

1. What is the superior extent of the pleural cavity?

a. The superior extent of the pleural cavity is 2-3 cm into the neck and is covered by the cupula of the cervical part of parietal pleura.

1. Where are the visceral and parietal layers of pleura continuous?

a. The visceral and parietal pleura are continuous at the hilum of the lung.

What is the condition called when air enters the space between the parietal and visceral pleura?

pneumothorax