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A BULLET TO THE BACK -- November 2016

Case Presentation

Paramedics arrive to find a young male complaining of back and chest pain after sustaining a gunshot wound to the back. Primary survey shows an agitated, diaphoretic male lying on the pavement. He is alert and shouts in pain with any movement. Secondary survey shows an obese male, GCS 15, with a stable and symmetric chest wall and decreased breath sounds over the right chest. There is a single gunshot wound to the right mid-back at T6 level; no “bubbling” or sucking sounds are present. Abdomen is obese, soft, and non-tender. The patient is moving all extremities. Vital signs include HR 125, RR 24, O2 saturation 88% on RA, increasing to 98% with NRB, and initial BP of 102/65.

 

1.

What immediate treatment priorities should be considered in this patient ?

While the patient gives a history of gastritis, which could offer a simple explanation of her epigastric pain and nausea, the possibility of other more serious causes must be assessed first. These include cardiac ischemia or infarction, stomach/intestinal ulcers, pneumonia, and intra-abdominal infection or injury.  In this patient with multiple risk factors for cardiac disease – older age, diabetes, high blood pressure, and high cholesterol – presenting with upper abdominal pain, the possibility of atypical presentation of myocardial infarction (MI) must be considered first as this will directly impact field management and destination decision. 

2.

What essential test should be performed in the field?

In the patient with a penetrating torso injury, the primary focus is transport without delay to the nearest trauma receiving facility. Paramedics should avoid any procedures that would delay transport to definitive care, including advanced airway management, IV placement and spinal motion restriction, unless necessary to preserve life. However, our military’s experience in the ongoing Middle East conflict has identified several potentially lifesaving procedures that can be accomplished without delaying transport of an unstable trauma patient. These include prevention of hypothermia, control of external hemorrhage, and needle decompression of tension pneumothorax.

Secondary evaluation in trauma patients must include assessment the patient’s respiratory status, including careful auscultation for breath sounds in any patient with possible thoracic/chest trauma. Palpation of the chest wall can also reveal crepitus from air escaping the lungs into the subcutaneous tissues.  Gunshot wounds should be suspected of penetrating the thorax anytime a wound is noted between the shoulders and the umbilicus. In the patient above, secondary survey noted decreased breath sounds in the right chest, which, in the context of a gunshot wound, produces a clear provider impression of open pneumothorax. The patient is also noted to be in a state of diminished perfusion. While his blood pressure is not consistent with decompensated shock, the seasoned medic will note that this pressure is lower than would be expected in an agitated, obese male endorsing significant pain. When combined with the additional findings of diaphoresis, tachycardia and hypoxia, the paramedic should be concerned for potential rapid decompensation. The paramedic must decide whether decompensation is due to hypovolemia from internal/external hemorrhage, neurogenic shock due to spinal cord injury, or obstructive shock due to pericardial tamponade or tension pneumothorax.

In this patient with penetrating trauma to the chest and evidence of compensated shock, obstructive shock from tension pneumothorax or pericardial tamponade should be strongly considered. It is a life-threatening situation, and one that can be temporized pending transport to definitive management. This patient’s initial vital signs do not indicate a need for immediate invasive prehospital treatment. However, paramedics should closely monitor and frequently reevaluate for changes in blood pressure, oxygen saturation, or mental status.

3.

Case Continuation?

Approximately two minutes before arriving to the Trauma Center, the patient became severely agitated, attempting to remove his oxygen mask and get up from gurney. SpO2 decreased to 86% with the patient agitated and pulling at his lines. Repeat blood pressure was 86/45.

4.

What immediate life-saving interventions should be performed?

The patient’s sudden and significant agitation, in the setting of major traumatic injury, should be considered a form of altered mental status, likely due in this case to his hypoxia and hypotension. Immediate steps should be taken to protect the patient and EMS personnel from further injury.

Tension pneumothorax occurs when air builds up in the space between the lung and the chest wall. Air may enter through a damaged chest wall (as in a sucking chest wound) or through damaged lung tissue during inspiration – this is a potential risk to monitor for when initiating positive-pressure ventilation in a patient with a possible pneumothorax.   Unlike a simple pneumothorax, where the lung parenchyma seals quickly after injury, in a tension pneumothorax the damage to the lung or chest wall is large enough to allow ongoing air entry into the pleural space. As the air builds up, it prevents expansion of the remaining undamaged lung tissue, and exerts pressure on the mediastinal structures, severely limiting cardiac output. The patient thus develops hypoxia and hypotension as a result of this tension physiology.

Initial evaluation of this trauma patient noted decreased breath sounds in the right lung fields. The patient’s status is now worsening. In this situation, immediate needle thoracostomy is indicated. Given the patient’s agitation, it is likely impossible to repeat a good lung assessment; nor is it necessary to “check” that the breath sounds remain decreased on the right. Needle thoracostomy should be performed with a 14g catheter-over-needle designed for this purpose. The needle should be placed into the chest wall in the 2nd intercostal space, directly over the superior border of the 3rd rib, or in the 4th or 5th intercostal space in the anterior axillary line. This lateral placement may allow easier landmark identification in an obese patient. While many personnel fear “going to deep” with the 8cm thoracostomy needle, research on adult trauma patients in Los Angeles demonstrated an average chest wall thickness of 5cm at this location . In addition, a review of complications in needle thoracostomy showed the most frequent complication was failure to penetrate through the chest wall into the thorax .

The needle should be inserted until a rush of air or blood is felt, or if a syringe is attached, until the plunger withdraws easily. The needle should be advanced another centimeter after entering the thoracic cavity and then withdrawn while the catheter is further advanced to the hub. The needle should NOT be left in place as it can cause injury to the lung once the lung expands. The hub should be left uncovered, and can be secured to the chest wall by butterfly tape strips. There is no need for a one-way valve, since the internal thoracic pressure of a tension pneumothorax is much greater than the atmospheric pressure (hence the rush of air through the needle-catheter on entire the thoracic cavity). Therefore paramedics should not be concerned that air would enter the chest cavity through the catheter.

If using the alternate location for needle thoracostomy at the 4th or 5th intercostal space in the anterior axillary line, paramedics must be trained in this technique, and should practice landmark identification and placement prior to using it in the field. It is important to note that landmarks in this area may appear different depending on whether the patient’s arm is abducted (raised above the head) or lying at their side. Most importantly, the needle should never be placed below the patient’s nipple line in a male, or below the inframammary crease in a female, and preferably just above the nipple line (male) if the patient’s arm is at their side. Placing the needle too low, or angling it caudally rather than inserting it perpendicular to the chest wall, may result in injury to the liver on the right or to the heart on the left. Successful release of the tension pneumothorax should produce a prompt increase in SpO2 and blood pressure. Therefore, blood pressure should be reassessed shortly after placing the needle.

Case study

Photo credit: http://www.littcase.com/cases/ID0203-en/en/page-N10183.html

In this patient, pulse oximetry increased to 96% after needle thoracostomy, and repeat blood pressure was 100/55. Heart rate remained 135 and the patient’s agitation decreased.

5.

What other interventions may be indicated in this patient?

In the patient with potential multisystem trauma, despite findings consistent with pneumothorax, paramedics must consider the possibility of multiple simultaneous injuries. It should be noted that obesity may create difficulty in assessing the patient, particularly with abdominal palpation. In the patient with decompensated shock after trauma, the paramedic will need to decide: 1) whether to provide IV fluids, and 2) whether to discontinue oxygen after the increase in the patient’s SpO2.

In the setting of penetrating thoracic trauma, it is generally accepted that receiving large volumes of IV fluids increases risk of mortality. L.A. County abides by the management principle of permissive hypotension, in which IV fluids such as normal saline are deferred for patients without profound hypotension. Despite this patient’s decreased blood pressure, tachycardia and diaphoresis, paramedics should avoid administering IV fluids while the systolic blood pressure is >90 mmHg. The patient will likely require prompt blood product transfusion in the Emergency Department. However, administering normal saline may increase coagulopathy, making it harder to control bleeding both in the ambulance and at the trauma center .

Similar to the blood pressure, the patient’s SpO2 improved, but did not normalize, after needle thoracostomy. The profound increase in oxygen and improved blood pressure may incorrectly prompt the paramedic to titrate down, or fully discontinue, the high flow O2 that was initially placed. However, continued high-flow oxygen is indicated because it promotes faster reabsorption of the pneumothorax. Therefore, by Medical Control Guideline 1304, high flow oxygen should be continued via NRB in any spontaneously breathing patient with suspected pneumothorax, regardless of the patient’s SpO2.

6.

Case conclusion

The patient remained hypotensive and tachycardic on arrival at the receiving trauma center. A chest tube was placed and 700ml of blood was immediately returned through the chest tube. Given the patient’s persistent hypotension and large bleeding into the chest tube, he was taken emergently to the operating room where bleeding from a small pulmonary vein near the gunshot wound was found and controlled. The patient did well following surgery and was discharged on hospital day 4 after removal of his chest tube. 

 

Take Home Points

  • Most pneumothoraces do not require prehospital needle thoracostomy. However, the development of profound hypotension and severe hypoxia in a patient with suspected pneumothorax warrants immediate needle thoracostomy to prevent cardiovascular collapse and traumatic arrest.
  • Needle thoracostomy should be performed with an 8cm catheter-over-needle in the 2nd intercostal space at the mid-clavicular line or in the 4th intercostal space at the anterior axillary line.
  • Paramedics must be careful to place the needle at or above the nipple line if using the lateral site.
  • In patients with penetrating trauma to the chest or abdomen, IV fluids should be avoided unless systolic blood pressure is <90 mmHg, as administration of fluids has been linked to worse outcomes.
  • High flow O2 should be used for any patient with shock/poor perfusion, and for any patients with suspected pneumothorax regardless of oxygen saturation or perfusion status.

 

References

[1] Inaba K, Ives C, McClure K, et al. Radiologic evaluation of alternative sites for needle decompression of tension pneumothorax. Arch Surg. 2012; 147(9): 813-8.

[2] Wernick B, Hon HH, Mubang RN, Cipriano A, et al. Complications of needle thoracostomy: A comprehensive clinical review. Int J Crit Illn Inj Sci. 2015 Jul-Sep;5(3):160-9. 

[3] Curry N, Davis PW. What’s new in resuscitation strategies for the patient with multiple trauma? Injury. 2012 Jul; 43(7): 1021-

 


By Shira Schlesinger, MD, MPH, Los Angeles EMS Agency