ED Management of the MVC Patient: Pearls and Pitfalls

Authors: Paolo N. Grenga, MD (EM Resident Physician, University of Rochester Emergency Medicine Residency), Audrey N. Paulzak (Neurosurgery Resident Physician, University of Rochester Neurosurgery Residency), and Ryan P. Bodkin, MD (EM Associate Program Director, University of Rochester Emergency Medicine Residency) // Edited by: Alex Koyfman, MD (@EMHighAK – EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) and Manpreet Singh, MD (@MPrizzleER – Assistant Professor of Emergency Medicine / Department of Emergency Medicine – Harbor-UCLA Medical Center)

Introduction

Motor vehicle crashes (MVCs) are a leading cause of death during the first three decades of Americans’ lives.  In 2012 the Fatality Analysis Reporting System (FARS) recorded over 31,000 fatal MVCs in the US [1].  According to the CDC, this equated to 9.4 men and 4.7 women per 100,000 killed in MVCs [2].  In the same year, 4,743 pedestrians were among those killed, with an estimated 76,000 injured in traffic crashes [3].  It is no surprise, then, that a substantial number of trauma patients presenting to emergency departments nationwide are victims of MVCs.  This patient cohort presents unique challenges to the emergency physician.  Many of these challenges, however, can be mitigated by a well-practiced, systematic approach to the management of all trauma patients, such as that outlined in Advanced Trauma Life Support (ATLS).  Winters’ et al. present one such approach that will provide the framework for this discussion [4]:

Case

You are working in an emergency department of a Level 1 Trauma Center when you receive a report from an incoming flight crew.  In tow, they bring you a 28-year-old male who, after drinking alcohol, lost control of his SUV, causing it to roll over multiple times across the median of a busy interstate before it struck a tree.  He was reportedly ambulatory at the scene and complained only of neck pain when EMS arrived.  He had no obvious deformities and smelled of alcohol.  Given the severe mechanism of injury and significant delay posed by ground transport, the decision was made to airlift him to your hospital.  Vital signs were stable en route.  However, after being given a dose of fentanyl, the patient suddenly became apneic and required bag valve mask ventilation.  They are 10 minutes out.

What are your first thoughts about this case?  What considerations must be made?  What resources should be gathered, if possible, prior to patient arrival?  What life and limb threats should be identified and addressed first? 

Emergency Department Management of the Motor Vehicle Accident Patient

Using the approach outlined by Winters et al we will address the key management considerations for the above case (Figure 1).

Identify the need to immediately control the airway

Emergency physicians are well acquainted with the ABCs of the primary survey.  In keeping with this approach, one of the first decisions in the management of the MVC trauma patient is whether to immediately control the airway [4, 5].  Recognizing the indications for definitive airway management can be life-saving. Table 1 outlines specific situations that may connote the need for definitive airway management in the MVC patient.

The LEMON mnemonic is a well-established memory tool that can predict the ease or difficulty with which laryngoscopy may be performed (Figure 2).  Anatomic features that may make intubation difficult include short neck, receding mandible, large tongue, protruding maxillary incisors and obesity.  Mouth opening and hyoid-chin distance of 3 finger breadths or more are reassuring.  Similarly, thyroid-cartilage – mouth floor distance of at least 2 finger breadths is reassuring (Figure 3).  Mallampati score of III (soft palate, base of uvula visible) and IV (only hard palate visible) suggest difficult intubation.  Patients with limited neck mobility, either from baseline disease or due to cervical immobilization are also more difficult to intubate [4,7].

Having a deliberate, algorithmic approach (Figure 4) like that proposed by the American Society of Anesthesiologists can aid the emergency physician by providing a logical, stepwise approach to selecting the best airway management strategy in MVC trauma patients, providing order in situations that can be chaotic [6]. Regardless of what algorithm approach you use, it is important to plan ahead and have all available airway management strategies at the bedside.

When trying to predict potential difficulties with intubation, a helpful strategy is to remember the “ABCs” of airway.  Consider the presence of the following to anticipate how patient pathology may complicate endotracheal intubation and RSI.  For example, be cognizant of how direct airway trauma and cervical spine injuries (and need for strict spine immobilization) may make intubation more difficult.  Have airway adjuncts available and have a low threshold to call for backup.  Choose neuroprotective RSI agents in patients with traumatic brain injuries.  Assume a low physiologic reserve in chest injury patients and anticipate rapid desaturation despite adequate preoxygenation efforts.  Maximize preload in hemodynamically unstable patients before giving RSI agents (i.e. Midazolam) that might worsen hypotension by sympatholysis.

Review – Identify the need to immediately control the airway [4]

Pearls

• Know the indications for intubation
• Perform a focused airway assessment to predict difficulty – LEMON, airway “ABCS”
• Maximize preload in hypotensive patients before RSI
• Have rescue devices, equipment and backup personnel available

Pitfalls

• Failure to predict the patient’s anticipated course
• Failure to protect the airway before interfacility transfer
• Intubation using RSI of the hypotensive patient before volume resuscitation

Case Continued

Given the patient’s abrupt change in mental status and apnea, you decide to call a trauma alert before he reaches the emergency department.  While the trauma team is being mobilized, he arrives.  On initial examination, you see an adult male in a cervical collar without spontaneous respirations being supported by bag valve mask ventilation.  Blood pressure and heart rate are normal.   You decide to intubate given his lack of spontaneous respirations.  While maintaining strict in line cervical spine stabilization, the patient is intubated with video laryngoscopy. Endotracheal tube placement is confirmed by direct visualization of the tube passing through the cords and by chest x-ray.  He is being placed on a ventilator when the trauma team arrives. 

Identify and control immediate threats to central perfusion

Once the patient has a definitive airway, the next priority is to identify and treat injuries that, if left unchecked, will lead to cardiovascular collapse.  A rapid and thorough primary and secondary survey will usually allow the emergency physician to identify many of these injuries.  Adjuncts to the primary survey including bedside ultrasonography and plain film x-rays, are especially useful if the patient does not respond to initial volume resuscitation.  Be sure to keep non-hemorrhagic causes of hypotension in the differential diagnosis (i.e. cardiogenic, spinal shock).  Identify and mark all sites of penetrating trauma prior to imaging [4].

> Hemorrhagic injuries

1. External bleeding

• Apply direct pressure by hand, then with dressing
• Elevate extremity if possible
• Apply hemostatic dressings to non-compressible sites
• Apply tourniquet to refractory hemorrhages. Place as proximal as is safe (so as not to compress distal to an undiscovered hemorrhage)
• Infants and children can rapidly exsanguinate from scalp lacerations [8,9]

 2. Intrathoracic bleeding

Rapid acceleration/deceleration in restrained occupants of MVCs increases the risk for traumatic aortic catastrophe including transection, rupture and dissection.  Perform a thorough vascular examination for pulse deficits and look for mediastinal widening or opacities on chest x-ray. The mediastinum may appear falsely widened and the heart magnified on the portable AP view in normal patients.

All hemothoraces should be considered for drainage, especially in patients with inadequate oxygenation/ventilation.  Persistent opacities on chest x-ray can be evaluated in delayed fashion by CT to determine whether significant undrained fluid exists.  Indications for emergency thoracotomy include immediate drainage of more than 1000 cc of blood immediately after tube thoracostomy, drainage of 1500 cc from a chest tube in any 24 hour period, continued bleeding from the chest (150-250 cc/hr for 2-4 hours) or repeated need for blood transfusion to maintain hemodynamic stability [10, 14].

3. Intra/retroperitoneal bleeding [11]

Bedside ultrasound has high diagnostic yield in blunt trauma patients, including MVC victims.  Physical exam finding of a positive seatbelt sign can increase the pretest probability of intra-abdominal injury.  Using the Focused Assessment with Sonography for Trauma (FAST), intraperitoneal fluid is detected with high sensitivity and specificity as an indirect marker of such injury (Figure 7).  In the hypotensive blunt abdominal trauma patient (where free fluid detected by ultrasound is assumed to be blood), a positive FAST exam mandates laparotomy. Note, however, that in patients with pelvic ring fractures or those in motorcycle accidents, fluid detected might represent urine from bladder rupture. In stable patients, further characterization of intraperitoneal fluid detected by bedside ultrasound can be done by CT or CT angiography.

The body has multiple compartments into which it can hemorrhage.  Be sure to consider the thoracic, abdominal (intra- and retroperitoneal), and pelvic compartments, as well as the proximal upper extremities and thighs, as all serve as potential spaces for significant volumes of blood loss.  Indirect physical exam signs such as abdominal or flank ecchymosis may be present on exam, but their absence does not rule out retroperitoneal hemorrhage (Figure 9).

4. Pelvic fractures

The mortality rate for patients with hypotension and pelvic fractures is high, ranging from 5-30% and the presence of such injuries indicates a high force of impact [5].  Care must thusly be taken to limit exsanguinating hemorrhage from pelvic fractures.  Disruption of the pelvic ring can tear the pelvic venous plexus and the internal iliac arteries, causing massive hemorrhage.  The most common type of pelvic fracture is lateral compression (60—70% frequency) and tends to occur when a patient is struck from the side.  Vertical sheer fractures and anterior-posterior compression fractures, or “open book” fractures (Figure 10, 11), occur less commonly.

Classically, emergency physicians are taught that patients with pelvic instability on exam, hypotension and open book fracture on pelvic radiograph require pelvic orthotic device (POD) placement [5].  According to EAST guidelines (2011), however, the use of a pelvic orthotic device does not seem to limit blood loss in patients with pelvic hemorrhages.  Use of a POD does seem to effectively reduce fracture displacement and decreases pelvic volume [10].  If a POD is placed, be sure that it is situated against the greater trochanters.  Internal rotation of the lower extremities also appears to decrease the pelvic volume [5].  Intubate after the pelvic binder is placed, as neuromuscular blockade may allow for expansion of the pelvic volume [12].

5. Long bone fractures

Femoral fractures can be of hemodynamic significance, as the thigh can hold ~1-2 liters of blood.  Assess neurovascular status and apply a traction splint as soon as is safe to limit hemorrhage and ease patient discomfort.  Be sure to monitor for changes in neurovascular status and skin ulceration post placement of traction splint [5].

> Non-Hemorrhagic injuries

1. Pericardial tamponade

Failure of the patient to respond to initial fluid resuscitation should prompt the emergency physician to assess for non-hemorrhagic causes of hypotension.  The patient with blunt trauma to the chest or abdomen, with obvious sternal or chest injuries and refractory hypotension, is at risk for pericardial tamponade from traumatic effusion.  Assess for hypotension, JVD and muffled heart sounds (Beck’s triad).  Suspicion for pericardial effusion is increased if these are present and the lungs sound clear, but they are not always present.  Unstable patients with pericardial tamponade will require immediate bedside pericardiocentesis.  This can be done blind if the patient is in extremis or with ultrasound guidance.  Have a low threshold to ask for assistance from a cardiothoracic surgeon, if available.

2. Tension pneumothorax

Thoracic ultrasonography has higher sensitivity and specificity than a single AP plain film in detecting pneumothorax [15].  Tension pneumothorax is a clinical diagnosis and is indicated by acute respiratory distress, subcutaneous emphysema, unilateral absent breath sounds, hyperresonance to percussion, and tracheal shift.  Its presence mandates immediate needle decompression with subsequent chest tube placement.  Tension pneumothorax can be iatrogenic as well – beware auto-PEEP in patients with obstructive disease at baseline who are intubated following trauma, and allow for permissive hypercapnia (low lung volumes, low respiratory rate) to mitigate this risk.

3. Myocardial contusion

Persistent hypotension despite adequate fluid resuscitation, especially with obvious chest trauma, can be secondary to myocardial contusion.  Monitor for signs of cardiogenic shock, including hypotension, cool or edematous extremities, pulmonary edema, and/or JVD.  ECG may show signs of ischemia or aberrant conduction.  Bedside echocardiography may show regional or global wall motion abnormalities.  Trend serial troponins to monitor severity and do not hesitate to obtain repeat ECGs if exam or symptoms change.  Patients may require pressor support with dobutamine or epinephrine to restore or improve cardiac contractility.

4. Neurogenic shock

Neurogenic shock results from significant high spinal cord injuries and/or disruption to the sympathetic chain.  Look for priapism, hypotension, bradycardia and peripheral vasodilation on examination.  All trauma patients in MVCs should be evaluated for cervical spine injury!  Maintain strict spine precautions and, if spinal cord injury is present, maintain adequate MAP goals (usually 85 – 90 mmHg) by fluid resuscitation and pressor support, if needed.  Do not delay notification of an orthopedic surgeon or neurosurgeon, if available, once significant spinal cord injury is suspected or confirmed by imaging.

Atlanto-occipital dissociation can occur in patients with significant neck trauma (i.e. “whiplash”) that may occur in MVCs, especially in rapid acceleration/deceleration accidents.  It results from disruption of the tectorial membrane and alar ligaments and results in significant instability of the skull on the cervical spine.  This injury is associated with significant morbidity and mortality, garnering itself the infamous moniker of “internal decapitation.”  If clinical suspicion for this is high, deliberate and rapid evaluation via sagittal CT images can be done by the emergency physician.

The Powers ratio (Figure 16) is a measurement of the relationship of the foramen magnum to the atlas.  The ratio, AB/CD, is measured as the ratio of the distance in the median (midsagittal) plane between the:

1. Basion(A) and the posterior spinolaminar line of the atlas (B) and,
2. Opisthion(C) and the anterior arch of the atlas (D)

Normal values are <1 on plain radiographs and <0.9 on CT. If this ratio is >1, then atlanto-occipital dissociation should be suspected [13].

The atlantodental interval is the horizontal distance between the anterior arch of the atlas and the dens of the axis.  An atlantodental interval > 3 mm in adult males or > 2.5 mm in adult females suggests atlanto-occipital dissociation injury.

The basion-dens interval is the distance between the most inferior portion of the basion and the most superior aspect of the dens in the sagittal plane.  A basion-dens interval > 8.5 mm on CT (> 12 mm on plain radiographs) suggests atlanto-occipital dissociation injury [13].

Coincident medical conditions

Trauma resuscitations are can be chaotic and many present with little warning.  To the extent possible, try to obtain as accurate and detailed a history as possible from prehospital providers and friends or family of the patient.  Attempt to develop an understanding of whether a MVC, for example, was the most proximate cause of a patient’s pathology or if the accident was caused by an acute medical emergency.  Consider causes of sudden loss of consciousness or cardiac arrest in the patient extracted from the scene of an accident, including acute myocardial infarction, malignant dysrhythmia, massive pulmonary embolism, ischemic/hemorrhagic stroke or aneurysmal subarachnoid hemorrhage.

Review – Identify and control immediate threats to central perfusion [4]

Pearls

• Evaluate for hemorrhagic and non-hemorrhagic causes of shock
• Consider other causes of shock, including cardiogenic and neurogenic shock
• Use adjuncts including bedside ultrasonography and plain films to aid in diagnosis
• +FAST in unstable BAT patient = OR
• Consider how underlying medical conditions, if known, are affecting the presentation

Pitfalls

• Failure to recognize the need for immediate surgical exploration
• Delays caused by diagnostic testing (i.e. CT)
• Inadequate resuscitation
• Failure to initiate early transfusion
• Failure to consider non-hemorrhagic causes of traumatic shock
• Failure to consider more than one cause of shock in the patient with multisystem injury
• Failure to consider coincident medical causes of shock in the injured patient

Case Continued

In tandem with the trauma team, the secondary survey commences.  The airway is controlled.  Chest rise is symmetric with clear lungs.  No crepitus or chest wall deformities are noted.  Central and distal pulses are palpable, symmetric and equal.  Upon rolling the patient, cervical spine step off is noted, as is right-sided flank ecchymosis.  Exam is otherwise notable for scattered abrasions on the extremities.  FAST exam is unremarkable and plain films of the chest and pelvis are reassuring.  IV access has been obtained and the patient is prepped for the CT scanner. 

Identify and address severe intracranial injuries

If a definitive airway has not yet been established, it is imperative that a brief but thorough neurologic examination (GCS, pupillary exam, motor asymmetry) be performed prior to intubation. Choose neuroprotective agents for RSI and avoid causing hypotension.  Once a definitive airway is established and resuscitation on-going, the emergency physician should determine whether the patient has intracranial hypertension.  Signs of this include rapid decline in or loss of a neurologic examination, pupillary asymmetry or motor posturing.  If there is concern for an active brain herniation syndrome, elevate the head of the bed (or reverse Trendelenburg if patient is on spine precautions) to 30 degrees and administer bolus dose mannitol (1 – 1.5 g/kg IV) or hypertonic saline (250 cc of 3% saline IV).  Avoid either agent in the setting of hypotension. Hyperventilation with goal PCO₂ of 35 – 40 mmHg can decrease ICP.

Identifying acute traumatic intracranial pathology by CT must take priority over all other interventions once the airway is established, life-threatening hemorrhage is controlled and adequate perfusion is achieved.  Transfer to CT should not be delayed, as identifying a life-threatening surgical intracranial lesion is the next priority. Any presumed intra-abdominal pathology, extremity compromise or external hemorrhage can be managed while the neurosurgical team is being mobilized and preparing the operating room. Do not attribute altered mental status or neurologic deficit to intoxication, even in the patient with minor injuries from a MVC.

If an MVC patient who has been thoroughly examined and deemed stable experiences a decline in GCS of more than 2 points, they should return to the scanner for a repeat CT of the head to assess for delayed contusions or development of intracranial hemorrhage.

Review – Identify and address severe intracranial injuries [4]

Pearls

• CPP = MAP – ICP
• Do NOT delay CT imaging once safe
• Have a low threshold for obtaining repeat CT

Pitfalls

• Failure to consider reversible causes (hypoglycemia, hypoxia, shock)
• Failure to manage overall patient with respect to perfusion and oxygenation
• Attribution of neurologic dysfunction to intoxication
• Delays in transfer to obtain head CT in a patient with severe neurologic dysfunction
• Failure to consider cerebrovascular disease in the at-risk patient

Case Continued

You accompany the patient to the CT scanner and view his imaging as it is obtained in real time.  Alarmingly, you note AO dislocation on the sagittal views of the cervical spine CT.  You confirm that the patient’s sedation is adequate and that his cervical collar remains securely in place. 

Identify and control other potentially life-threatening thoracic and abdominal/pelvic injuries

By this point in resuscitation the patient is likely hemodynamically improved.  Advanced imaging such as CT and CT angiography of the head and body can further characterize injuries that were detected by physical exam, ultrasound and plain radiographs.  Consider and evaluate for injuries that will require emergent operative intervention, including aortic dissection or rupture or perforated viscus.  Have a low threshold to administer empiric antibiotics.  If there is evidence of active hemorrhage on CT angiography, prepare the patient for embolization or stenting by interventional radiology.  Re-evaluate interventions such as chest tube placement for interval improvement in oxygenation, ventilation and adequate drainage.  If the patient has not improved despite initial interventions, repeat the primary and secondary surveys.

Review – Identify and control other potentially life-threatening thoracic and abdominal/pelvic injuries [4]

Pearls

• Re-evaluate response to interventions.  If little or no improvement, repeat primary and secondary surveys.
• Promptly follow up results of advanced imaging studies.
• Get necessary consultants on board ASAP.

Pitfalls

• Failure to diagnose aortic injury in a timely fashion
• Failure to diagnose hollow viscus injury
• Failure to appreciate potential for pelvic bleeding
• Inadequate drainage of pneumo/hemothorax
• Inadequate resuscitation

Case Continued

The rest of the patient’s imaging is notable only for a retroperitoneal hemorrhage on the right of unclear source.  He remains tachycardic but is hemodynamically stable with IVF administration.  Blood products arrive from the blood bank in anticipation of decompensation.

Identify and control potentially limb-threatening injuries

Limb-threatening injuries in the MVC patient include arterial injury, compartment syndrome and severe fractures or dislocations.  Evaluate for limb deformities and evidence of inadequate perfusion (pain, paresthesias, pallor, paralysis, pulselessness and poikilothermia).  Consider these in patients with prolonged extrication from vehicles that collapsed around them or from being pinned.  If hard signs of neurovascular injury are present, such as expanding hematoma, loss of distal pulses or active arterial bleeding, the patient must proceed directly to the OR.  In the absence of these, measure serial compartment pressures (hypoperfusion occurs at compartment pressures > 20 mmHg) in the affected limbs and obtain ABIs (normal is > 0.9).  Note that loss of sensation or pulse deficits are late findings in compartment syndrome.  The earliest, most sensitive finding is pain on passive ROM of the affected extremity.

Reduce dislocations and long bone fractures to decrease risk of neurovascular compromise and improve patient comfort.

Concomitant evaluation for crush syndrome should also be completed.  Obtain ECG and check serum potassium and treat for hyperkalemia from rhabdomyolysis with isotonic fluid, calcium gluconate and, if needed, insulin and dextrose.  Monitor and treat for acute kidney injury from myoglobin accumulation in the renal tubules.

Review – Identify and control potentially limb-threatening injuries [4]

Pearls

• Remember the 6 “Ps” of compartment syndrome:
• Pain, paresthesias, pallor, paralysis, pulselessness and poikilothermia
• Normal compartment pressures are < 20 mmHg
• Normal ABIs are > 0.90
• Hard signs of vascular injury include expanding hematoma, loss of distal pulses or active arterial bleeding

 Pitfalls

• Failure to proceed directly to surgery with hard signs of vascular injury
• Failure to control ongoing bleeding from extremity wounds
• Failure to perform an ABI with soft signs of vascular injury or knee dislocation
• Failure to consider and evaluate for compartment syndrome, especially in unconscious patients
• Failure to reduce and splint long-bone fractures
• Failure to reduce dislocations

Case Resolution

 The patient is evaluated by the spine and trauma teams.  He is taken to the OR on hospital day 2 for posterior fixation for AO dislocation which is successful.  His hemodynamics and hematocrit are monitored serially given his retroperitoneal hemorrhage, which ultimately is found to be caused by a traumatic lumbar artery rupture.  He undergoes arterial embolization by interventional radiology.  He is extubated on hospital day 5 and, impressively, walks out of the hospital on hospital day 8. 

References / Further Reading

1. National Highway Traffic Safety Administration (2014).NCSA Data Resource Website. Fatality Analysis Reporting System. Retrieved from https://www-fars.nhtsa.dot.gov/Main/index.aspx
2. CDC (2014, December).Buckle Up: Restraint Use in New York. Retrieved from https://www.cdc.gov/motorvehiclesafety/pdf/seatbelts/restraint_use_in_ny.pdf
3. National Highway Traffic Safety Administration (2014, April).Traffic Safety Facts 2012 Data. Retrieved from https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/811888
4. Winters, Michael E., DeBlieux, Peter, Marcolini, Evie G., Bond, Michael C., Woolridge, Dale P.Emergency Department Resuscitation of the Critically Ill. Dallas: American College of Emergency Physicians, 2011.
5. American College of Surgeons.Advanced Trauma Life Support Student Course Manual. Chicago: American College of Surgeons, 2012.
6. Apfelbaum, Jeffrey L. et al. “Practice Guidelines for Management of the Difficult Airway: An Updated Report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway.”Anesthesiology. 2013. 118: 251-270.
7. RT for Decision Makers in Respiratory Care (2009). Airway Management and the Challenge Presented by Obese Patients. Retrieved from http://www.rtmagazine.com/2009/10/airway-management-and-the-challenge-presented-by-obese-patients/
8. Dickinson, Edward T. “Point-of-Care Hemorrhage Control” Journal of Emergency Medical Services (2013). Retrieved from http://www.jems.com/articles/supplements/special-topics/putting-clamp-hemorrhage/point-care-hemorrhage-control.html
9. Nickson, Chris (2012). Life in the Fast Lane. Trauma! Extremity Arterial Hemorrhage. Retrieved from https://lifeinthefastlane.com/trauma-tribulation-030/
10. Eastern Association for the Surgery of Trauma (2016). East.org. EAST Practice Management Guidelines. Retrieved from https://www.east.org/education/practice-management-guidelines
11. Jang, Timothy, Gunabushanam, Gowthaman (2015). Medscape. Focused Assessment with Sonography in Trauma (FAST). Retrieved from http://emedicine.medscape.com/article/104363-overview
12. Critical Care Compendium (2016). Life in the Fast Lane. Pelvic Trauma. Retrieved from https://lifeinthefastlane.com/ccc/pelvic-trauma/
13. Gaillard, Frank et al (2016). Radiopaedia. Atlanto-occipital dissociation injuries. Retrieved from https://radiopaedia.org/articles/atlanto-occipital-dissociation-injuries
14. Mancini, Mary C., et al (2017). Medscape. Hemothorax Treatment & Management. Retrieved from http://emedicine.medscape.com/article/2047916-treatment
15. Nagarsheth, K., Kurek, S. “Ultrasound detection of pneumothorax compared with chest X-ray and computed tomography scan.”Am Surg. 2013. 77(4): 480-4.