First Aid for the USMLE Step 2 CS

Section 4. Practice Cases

Case 4. 25-Year-Old Man Presents Following Motor Vehicle Accident


Opening Scenario

John Matthews, a 25-year-old male, comes to the ED following a motor vehicle accident.

Vital Signs

BP: 123/88 mm Hg Temp: 100°F (38°C)

RR: 22/minute HR: 85/minute, regular

Examinee Tasks

1. Take a focused history.

2. Perform a focused physical exam (do not perform rectal, genitourinary, or female breast exam).

3. Explain your clinical impression and workup plan to the patient.

4. Write the patient note after leaving the room.

Checklist/SP Sheet

Patient Description

Patient is a 25 yo M.

Notes for the SP

 Exhibit pain in the left chest that worsens during inspiration and movement (ie, when you breathe in, hold your side and stop your breathing with a short gasp).

 Exhibit pain when your left chest is being palpated.

 Exhibit pain when your left upper abdomen is being palpated.

 Take fast, shallow breaths.

 Occasionally cough hard into a tissue.

 Moan occasionally and answer questions in short sentences.

Challenging Questions to Ask

“Do you think I am going to die?”

Sample Examinee Response

“Your condition raises concern and is obviously urgent. We will start by taking some images of your chest. Then, once we have a better idea of what is wrong, we can give you some medication to help you with your pain. If there is air or blood around your lungs, there is a procedure we can perform to release the pressure. We will be monitoring you very closely from this point on, and if you have any significant problems, we will be available to help.”

Examinee Checklist

Building the Doctor-Patient Relationship


 Examinee knocked on the door before entering.

 Examinee introduced self by name.

 Examinee identified his/her role or position.

 Examinee correctly used patient’s name.

 Examinee made eye contact with the SP.

Reflective Listening

 Examinee asked an open-ended question and actively listened to the response.

 Examinee asked the SP to list his/her concerns and listened to the response without interrupting.

 Examinee summarized the SP’s concerns, often using the SP’s own words.

Information Gathering

 Examinee elicited data efficiently and accurately.

Connecting with the Patient

 Examinee recognized the SP’s emotions and responded with PEARLS.

Physical Examination

 Examinee washed his/her hands.

 Examinee asked permission to start the exam.

 Examinee used respectful draping.

 Examinee did not repeat painful maneuvers.


 Examinee discussed initial diagnostic impressions.

 Examinee discussed initial management plans:

□ Follow-up tests.

 Examinee asked if the SP had any other questions or concerns.

Sample Closure

Mr. Matthews, you should always seek medical treatment after an accident like this. We must now observe you closely until we can determine what is causing your pain. We are going to run a few tests and take some imaging studies of your chest. We will also give you something for your pain and will observe your breathing to make sure you are getting enough oxygen. Do you have any questions for me?


HPI: 25 yo M c/o left chest pain and LUQ pain following an MVA. The patient struck a tree with his car at a slow speed. The chest pain is 8/10. It is exacerbated with movement or when he takes a deep breath, and nothing relieves it. He reports dyspnea and a productive cough with a low-grade fever but denies LOC, headache, change in mental status, or change in vision. No cardiovascular or neurologic symptoms. No nausea, vomiting, neck stiffness, or unusual fluid from the mouth or nose. No dysuria. His last meal was 5 hours ago. He denies being under the influence of alcohol or drugs.

ROS: As per HPI.

Allergies: NKDA.

Medications: None.

PMH: Infectious mononucleosis.

PSH: None.

SH: No smoking, occasional EtOH, no illicit drugs.

FH: Noncontributory.

Physical Examination

Patient is in acute distress, dyspneic.

VS: Temp 100°F, RR 22/minute.

HEENT: No JVD, no bruises, PERRLA, EOMI, no pharyngeal edema or exudates.

Chest: Two large bruises on left chest, left rib tenderness, decreased breath sounds over left lung field, right lung fields clear.

Heart: RRR; normal S1/S2; no murmurs, rubs, or gallops.

Abdomen: Soft, nondistended,BS, LUQ tenderness, no rebound or guarding, no organomegaly.

Skin: No bruises or lacerations.

Neuro: Mental status: Alert and oriented x 3. Cranial nerves: 2-12 grossly intact. Motor: Strength 5/5 in all muscle groups. Sensation: Intact to pinprick and soft touch.

Differential Diagnosis


Patient Note Differential Diagnoses

The most important steps in any trauma are to assess the ABCDEs: Airway, Breathing, Circulation, Disability (neurologic), and Exposure. In this case, the exam is separated from the trauma by several hours and the patient is able to walk and talk, somewhat negating the urgency of a typical ED evaluation. At the same time, chest pain and dyspnea are serious symptoms that require swift evaluation and intervention.

 Pneumothorax: A pneumothorax forms when air collects between the pleural and visceral layers of the thorax. Physical findings include a unilateral loss of breath sounds with hyperresonance, shift of the trachea away from the injured side (in the case of tension pneumothorax), and JVD. Although no JVD is present, this patient’s acute onset and distress suggest pneumothorax. CXR is the fastest diagnostic tool available.

 Hemothorax: This is defined by the presence of blood in the pleural space and is most commonly due to trauma. It presents with chest pain, shortness of breath, cough, decreased breath sounds on the involved side, and occasionally signs and symptoms of hypovolemic shock. The final diagnosis can be made by pleurocentesis or chest tube placement.

 Pneumonia: Most often community acquired and caused by Streptococcus pneumoniae, bacterial pneumonia can present with acute respiratory distress, fever, cough, pleuritic pain, and shaking chills. This patient has a productive cough, low-grade fever, and unilateral chest pain suggestive of pneumonia. However, traumatic causes should be ruled out first. Physical signs include tachypnea, crackles, egophony, and dullness to percussion. The CXR will show a lobar infiltrate, and sputum cultures may help identify the bacterial pathogen.

Additional Differential Diagnoses

 Rib fracture: Rib fractures are the most common chest injury and can result from almost any insult to the chest wall. A simple fracture could cause this patient’s pain on inspiration and cough. Rib fractures can also lead to pneumothorax. They can be diagnosed with a CXR.

 Splenic rupture: Splenic injuries are always of great concern following a trauma because they can cause significant blood loss very quickly. If this patient was exposed to infectious mononucleosis, his chances of splenic injury or bleeding are greater. Given that this patient’s pain is primarily left-sided in the chest area and LUQ, the spleen should be evaluated with an ultrasound exam followed by further imaging with an abdominal CT. On physical exam, it is important to evaluate for any signs or symptoms of organomegaly.

 Pleuritis: Inflammation of the pleural membrane can cause severe pain that increases with inspiration or movement. The physical exam is generally negative with the exception of the chest pain. This patient may have a simple viral pleuritis, but more emergent causes need to be ruled out first.

Diagnostic Workup

 CXR: On CXR, lobar consolidation may indicate pneumonia, hemothorax may cause linear consolidation, and tension pneumothorax will show mediastinal shift and tracheal deviation away from the pneumothorax. Rib fractures can also be diagnosed from the CXR if they are present.

 Sputum and blood Gram stain and culture: Used to screen sputum samples for the identification of bacterial pathogens such as S pneumoniae. Other stains, such as acid-fast stains and monoclonal antibodies, can identify tuberculosis and Pneumocystis jiroveci (formerly P carinii) and should be obtained if the history suggests that these are possibilities. A blood culture and Gram stain would also be useful given that the patient has a low- grade fever.

 Urine toxicology and blood alcohol level: These tests should be considered for any driver following a motor vehicle accident. Even though this patient’s car accident occurred a while ago, it is still necessary to evaluate his current situation.

 XR/CT—abdomen: Although a CT scan may be a more effective means of assessing patients for internal abdominal injury, a FAST scan (focused assessment with sonography for trauma) can quickly assess for intraabdominal bleeding, which may be advisable for this patient given his history of infectious mononucleosis. An AXR remains a quick way to rule out free air in the abdomen.

 Pulse oximetry: Although not as sensitive as ABG analysis, pulse oximetry is a fast, noninvasive measure of oxygenation. Remember that a patient with long-standing lung disease such as COPD may have chronically suppressed oxygenation, which is necessary to maintain respiratory drive.

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