Shortness Of Breath Case 5

Shortness Of Breath Case 5

A 20-year-old woman is brought to the emergency department after a severe traffic collision. Initial assessment reveals a tachypneic, tachycardic, hypotensive woman in acute distress. On examination, she has multiple contusions on the left Iateral chest wall and jugular venous distention (JVD). Her chest is hyperresonant to percussion and she has diminished breath sounds on the left. Her trachea deviates to the right. A chest x-ray film reveals diminished vascular markings on the Ieft. An ECG shows sinus tachycardia.


Q1
Which of the following is the most likely diagnosis?

/ A. Cardiac contusion
/ B. Hypovolemic shock
/ C. Pericardial tamponade
/ D. Pulmonary contusion
/ E. Tension pneumothorax


Q2
Which of the following is the most likely mechanism of this patient’s shock?

/ A. Fiuid in the pericardial space prevents diastolic filling
/ B. Hypoxia from rapid loss of pulmonary capacity impedes cardiac function
/ C. Malpositioning of the great vessels has impeded venous return
/ D. Massive bleeding into the pleural space has led to hypovolemia
/ E. Myocardial dyskinesia has led to cardiac insufficiency


Q3
Which of the following is the most appropriate immediate management?

/ A. FIuid bolus
/ B. Needle thoracostomy
/ C. Open thoracotomy
/ D. Pacemaker placement
/ E. Pericardiocentesis


Q4
When instrumenting the chest, instruments are inserted into the chest along the superior surface of the rib to avoid which of the following structures?

/ A. External oblique muscle
/ B. Intercostal artery
/ C. Parietal pleura
/ D. Phrenic nerve
/ E. Visceral pleura

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Shortness Of Breat Case 5 Answers

A1
The correct answer is E. This patient has the classic findings for tension pneumothorax. She has a history of severe trauma, and the findings of dyspnea, tachypnea, tachycardia, tracheal deviation, unilaterally decreased breath sounds, and hyperresonance to percussion. This is a life-threatening condition that must be remedied immediately.
Cardiac contusion (choice A) would not present with these findings. Patients will be hemodynamically unstable, often showing various arrhythmias on ECG. They will not have tracheal deviation, JVD, or hyperresonance to percussion.
Hypovolemic shock (choice B) could not account for the patient's jugular venous distention, hyperresonance to percussion, diminished breath sounds, tracheal, or chest x-ray findings.
Pericardial tamponade (choice C) is a life-threatening condition often seen in the trauma setting. Beck's triad characterizes pericardial tamponade: decreased heart sounds, jugular venous distention, and hypotension. Patients may also be tachycardic with pulsus paradoxus.
Pulmonary contusion (choice D) may produce respiratory distress immediately after trauma occurs but usually complicates the chronic course. It would not produce tracheal deviation, or hyperresonance to percussion. On x-ray films it would appear as an ill-defined opacity.


A2
The correct answer is C. As discussed above, this patient is suffering from tension pneumothorax, and the mechanism of shock in this condition is mechanical. As air becomes trapped in the pathologic side of the chest, the ipsilateral chest cavity expands. The enlarging cavity begins to encroach upon the mediastinal and contralateral chest contents, and as the contents herniate contralaterally, the great vessels become kinked and compressed. This inhibits venous return and thus diastolic filling. This results in shock. Immediate decompression of the chest will restore venous return.
As discussed above, this patient does not have pericardial tamponade (choice A). In pericardial tamponade, fluid in the pericardial sac surrounding the heart prevents diastolic filling, resulting in shock. Immediate decompression of the pericardial space is indicated.
While hypoxia (choice B) may result from pneumothorax, this is not the primary reason for the patient's shock.
Massive bleeding into the pleural space (hemothorax; choice D) may cause shock in a fashion similar to pneumothorax. It is unlikely that this patient has a hemothorax, however, as evidenced by the hyperresonance to percussion.
Choice E is incorrect. Severely contused myocardium would likely show ECG abnormalities. A normal ECG makes this diagnosis less likely, and thus not a likely reason for this patient's shock.


A3
The correct answer is B. Since the tension within the chest cavity creates the danger, relieving it is the mainstay of treatment. Continued tension will continue to push the chest contents to the side contralateral to injury. This will "kink" the venous return to the heart leading to diminished end-diastolic volume with imminent cardiac collapse. In addition, the uninjured lung will have limited inspiratory capacity. Thus to accomplish immediate decompression, a needle is inserted in the second intercostal space at the mid-clavicular line.
This is followed by placement of a chest tube to manage the pneumothorax more chronically. This patient may have hypovolemia, as bleeding may be present, but her hemodynamic instability may be entirely due to the tension pneumothorax. Thus, fluid (choice A) may be given later, but treating the pneumothorax is a higher priority.
Open thoracotomy (choice C) would treat the pneumothorax, but would take longer than needle decompression, and may be more than is needed.
This case has given no justification for pacing the heart (choice D).
Pericardiocentesis (choice E) is used to treat pericardial tamponade, not pneumothorax.


A4
The correct answer is B. The intercostal vein, artery, and nerve traverse the inferior surface of the ribs in the intercostal groove. When placing instruments into the chest, these structures must be avoided. Damaging these structures can result in bleeding into the chest and may cause significant hemothorax. Thus, instruments are inserted along the superior surface of the rib.
The external oblique muscle (choice A) runs between the ribs from superior to inferior and laterally to medially. (Like the fingers of a hand placed in pants pockets.) This structure in invariably pierced when instrumenting the chest.
The parietal pleura (choice C) is the layer of pleura that adheres to the chest wall. It is also pierced when instrumenting the chest.
The phrenic nerve (choice D) innervates the diaphragm from spinal segments C3-5. It travels in the mediastinum and would not be at risk here.
The visceral pleura (choice E) is the thin layer of pleura that envelops the lung. It would be at risk for damage if the instruments were inserted into the chest too far. Placing the instrument in the proper orientation to the rib is of no consequence