Causes of Shock in the Trauma Patient

Created on Fri, 01/01/2016 - 19:53
Last updated on Sun, 10/29/2017 - 17:55

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Question 20 from the second paper of 2011 asked about the causes of shock in trauma, what distinguishing features they have, and what echocardiographic features are associated with them. Question 2 from the second paper of 2017 instead presented the candidates with a hypotensive burns patient who was pulled out of a garage explosion. The causes of shock in trauma are numerous, and the attempt to go through them systematically has led me to a tabulated form of answer, which is found in this chapter.

Here is a table of the possible causes of shock in trauma, with their clinical and echocardiographic features.

Causes of Shock in the Trauma Patient
Type of shock Cause Distingusihing features Echocardiographic features
Artifact of measurement Blood pressure measurement is inaccurate
  • strong pulse
  • disagreement between measurement modalities (eg. art line and NIBP)
  • Reassuringly normal-looking contractility and chamber size
Cardiogenic Cardiac contusion
  • S3
  • Pericardial rub
  • Anterior ST changes
  • Decreased contractility
  • Regional wall motion abnormality
Myocardial infarction
  • Complaints of chest pain
  • ECG changes
  • cardiac enzyme elevation
  • Decreased contractility
  • Regional wall motion abnormality
Arrhythmia
  • Rapid, irregular pulse
  • ECG
  • Rapid or irregular contraction
  • Poor atrial mobility (AF)
Obstructive Cardiac tamponade
  • Raised JVP, CVP
  • Pulsus paradoxus
  • JVP rises on inspiration (Kussmaul's sign)
  • Muffled heart sounds
  • Right atrial systolic collapse and right ventricular diastolic collapse
  • Increased pericardial fluid
  • Swinging heart
  • Dilated IVC
Tension pneumothorax
  • Surgical emphysema
  • Tracheal deviation away from side of pneumothorax
  • Quiet breath sounds on side of side of pneumothorax
  • Reduced left ventricle end diastolic area
  • Distended superior vena cavae
Fat embolism
  • Confusion
  • Petechial rash over face, axillae, root of neck
  • Hypoxia
  • Features of right heart strain
Neurogenic Spinal injury
  • hypotension without compensatory tachycardia
  • warm exremities
  • paralys
  • Decreased contractility
  • Normal IVC diameter
Hypovolemic Massive blood loss
  • Jugular venous pressure not visible
  • Positive response to passive leg raise
  • Reduced left ventricle end diastolic area
  • LV end systolic cavity obliteration
  • Reduced inferior vena cava diameter with pulse variation
Distributive Adrenal failure (pituitary injury)
  • Warm extremities
  • Bradycardia
  • Hypotension
  • refractory to fluids and vasopressors
  • evidence of base of skull fracture
  • decreased contractility
  • Normal IVC diameter
Anaphylaxis
  • angioedema
  • urticaria
  • facial swelling
  • wheeze
  • Hyperdynamic circulation
  • Increased contractility

Echocardiographic investigation of shock in trauma

A certain James Lai (FRCA, FANZCA) has published a brilliant set of slides for public delectation, which does this topic justice.

A 2011 study has also demonstrated that fluid assessment can be carried out quickly and effectively using IVC diameter and IVC respiratory variation, although in this study a surgical intensivist or an ultrasonographer (rather than an ED registrar) were performing the study. To address this concern, the same group later demonstrated that even a shaved ape could be trained to perform a limited goal-directed TTE.

Interestingly, there are also many studies of transoesophageal echo in trauma. One is tempted to salute the bravery of the man who would jam a TOE probe down into a trauma patient. However, it certainly seems to be helpful. A study comparing transthoracic and trasoesophageal assessment has demonstrated that TOE is significantly more accurate, and that TTE in severe chest trauma usually gives unsatisfactory images.

 

References

Ferrada, Paula, et al. "Transthoracic focused rapid echocardiographic examination: real-time evaluation of fluid status in critically ill trauma patients."Journal of Trauma and Acute Care Surgery 70.1 (2011): 56-64.

Ferrada, Paula, et al. "Limited transthoracic echocardiogram: so easy any trauma attending can do it." Journal of Trauma and Acute Care Surgery 71.5 (2011): 1327-1332.

Chirillo, Fabio, et al. "Usefulness of transthoracic and transoesophageal echocardiography in recognition and management of cardiovascular injuries after blunt chest trauma." Heart 75.3 (1996): 301-306.

Sybrandy, K. C., M. J. M. Cramer, and C. Burgersdijk. "Diagnosing cardiac contusion: old wisdom and new insights." Heart 89.5 (2003): 485-489.