Priority Topic: Trauma

Key Feature 5a: In a patient with signs and symptoms of shock: Recognize the shock.
Skill: Clinical Reasoning, Selectivity
Phase: Hypothesis generation, Diagnosis

Key Feature 5b: In a patient with signs and symptoms of shock: Define the severity and type (neurogenic, hypovolemic, septic).
Skill: Clinical Reasoning, Selectivity
Phase: Physical, Diagnosis

You would expect a patient with shock to appear unwell and activate that nerve in your stethoscope that tells you a patient seems unwell. Indeed, this may very well be the case, but on other occasions, it may absolutely not be. Some patients are very sneaky. What may start as one or two symptoms or signs of shock may rapidly progress to full on shockity shock and impending risk of full circulatory collapse, as any sign of shock signals that the body is no longer able to sufficiently compensate for the lack of oxygen reaching the end organs. When it comes to decompensation, it is a slippery slope, so heed any warning and respect its authoritah. 

"SHOCR" symptoms and signs of real-deal shock:

• Symptomatic tachycardia (aka chest pain and shortness of breath)
• Hypotension, H+ (metabolic acidosis or elevated lactate)
• Oliguria
• Cool, clammy, diaphoretic skin
• Restlessness, agitation, altered level of consciousness

Early signs of circulatory compromise (or pre-shock) for which the body may still be compensating  include: 

• Tachycardia
• Tachypnea
• Dry mucous membranes
• Poor skin turgor
• Weak peripheral pulses
• Delayed capillary refill >3 seconds

Note the above signs are generally asymptomatic, and require a clinician to look for them. Anytime a patient is at risk of circulatory compromise, because they appear unwell or because information on history suggests risk (ex: infection, excess vomiting, possible allergic reaction, post-operative, etc.), it is imperative to look for these signs. Intervening during pre-shock means a better chance of preventing deterioration and securing a better outcome for the patient. With decompensation, pre-shock can quickly turn into shock, which can then ultimately lead to end-stage organ dysfunction, characterized by irreversible organ damage, multiorgan failure, and death.

It is also important to know that there are different types of shock, and that not all types present with all of the above features. This is another reason to have a high index of suspicion for shock or at least circulatory impairment when noticing the presence of any of the above symptoms or signs. These signs are also not specific, and may indicate other disease processes (ex: tachycardia in the setting of fever without circulatory compromise per se), but it is important to consider shock or impending shock on the differential to be able to react sooner rather than later if indicated.

Shock is generally classified as being 1 of 4 types, and it helps to narrow down the type of shock based on clues from the primary examination (if possible, but it's important to know that more than one process can be co-occuring) to determine more quickly the underlying etiology and provide definite treatment ASAP.

1. Hypovolemia (This could be from blood loss, third spacing, or some other loss such as diarrhea or vomiting, among others)
   1. Hypovolemic shock may present with signs of dehydration, which are typically not part of the presentation of other types of shock (think dry mucous membranes and reduced skin turgor). A history of bleeding or other source of fluid loss such as from excess vomiting, urination, diarrhea, fever, or sweating can suggest hypovolemia. Shock in the setting of trauma is always suspected to be hypovolemic unless proven otherwise (ex: from internal bleeding).
2. Cardiogenic (This could be from cardiac myopathy such as secondary to infarction, as well as a dysrhythmia or valvular dysfunction)
   1. Cardiogenic shock generally presents as hypotension in association with clinical manifestations of pulmonary edema (ex: diffuse lung crackles, distended neck veins). The heart is not able to pump forward so the blood basically backs up in the lungs and large vessels that transport blood to the heart, such as the jugular vein in the neck.
      
3. Obstructive (This could be from a massive pulmonary embolus, tension pneumothorax, cardiac tamponade, pulmonary hypertension, aortic dissection, or venacaval obstruction)
   1. Similar to cardiogenic shock, obstructive shock usually presents as hypotension associated with distended neck veins, but it is different in that it usually presents without clinical signs of fluid overload (ex: lung crackles, peripheral edema). 
      
4. Distributive (This could be from sepsis, anaphylaxis, toxic shock, neurogenic dysfunction, spinal shock, or an Addisonian crisis)
   1. Distributive shock is also known as warm shock, characterized by loss of peripheral vascular resistance and therefore hypotension associated with warm as opposed to cool extremities more characteristic of the other 3 types of shock. There may be other clues on history that point to an underlying etiology as well, such as a possible allergic reaction (raises suspicion for anaphylactic shock), known preceding infection (raises suspicion for septic shock), or regular corticosteroid use (raises suspicion for adrenal crisis secondary to steroid withdrawal), among others.