Recent question from an EMT student

Mottled arm

Mottled newborn

Hypoperfusion Question and Answer

Question: Good morning, just want to make sure I got it right, most emergencies have Hypoperfusion involve? (at least potentially) in other words, a dead person is in shock, so every life threatening situation is a shock situation, so all emergencies need to be treated for shock? (CHF, MI, CVA and even appendicitis can lead to shock) so, shock treatment is only needed if signs and symptoms of shock are present?

Answer: Not exactly.  Not every emergency results in hypoperfusion.  As an example. A person having an asthma attack is only having a respiratory emergency unless the hypoxia gets so severe it interferes with the ability of the heart to beat.   

A quick review of shock:

Hypovolemia is one for the four categories of shock.  This type of shock is caused by low volume of either blood (Hemorrhagic shock) or other fluid (Metabolic Shock).  Metabolic shock is caused by a loss of intracellular (inside the cells) or extracellular (outside the cells but not in the blood vessels) fluid.  Metabolic shock is usually caused by excessive vomiting, diarrhea, urination in Diabetic Ketoacidosis (DKA) and renal failure. It can rarely be caused by excessive sweating. Some books list plasma lost from burns as hemorrhagic shock and other list is as metabolic.  Usually it is considered metabolic shock.  Treatment of hemorrhagic shock involves the controlling of external bleeding, leg elevation, O2, and temperature control (keeping the patient warm).  Transport should be immediate and to a trauma center. Treatment of metabolic shock involves leg elevation, O2, and temperature control (keeping the patient warm).  Transport can be to any hospital, but if involves a pediatric patient it should be to a pediatric capable hospital. Hypovolemic shocks are the only shock that result on fluid being lost from the body. 

Cardiogenic shock is caused by one of four issues.  1.  Severe damage to the ventricles.  This can be caused by an AMI (heart attack), infection in the myocardium (heart muscle), or rarely trauma to the myocardium.  2.  Heart valves not working correctly and allowing blood flow to go backwards. 3.  A heat rate that is to slow (bradycardia) or a heart rate that is to fast (tachycardia).  When the heat rate is to slow the Cardiac Output (heat rate x stroke volume) drops because the number of time the ventricles are pumping is to slow.  In a tachycardia the problem is that the time between contractions (diastole) is so short the ventricles do not fill completely so stroke volume drops.  This is called decreased ventricular filling time.   EMT treatment involves O2 (sometimes the patient’s mental status will be so decreased that you can use the BVM), warmth, and rapid transport.

Distributive shock involves the smaller more peripheral blood vessels in the body.  The cause of hypoperfusion is the sudden vasodilation (widening) of these blood vessels. There is no blood loss; the blood is re-distributed from the vital organs to the skin and other non-vital area.  The result is that there is less blood going to vital organs.  Distributive shock is considered the most difficult shock to determine.  The reason why is as follows.  In all other shocks the skin is usually cool, pale, and diaphoretic.  Peripheral pulses are usually weak.  In distributive shock, the warm core blood is sent to the extremities and surface blood vessels.  Initially, the skin will be warm, pink (in light skinned patients), and dry.  The peripheral pulse will be strong. This will change if the shock is not treated. There are four types of distributive shock:

1.       Anaphylactic shock.  Caused by the body’s immune system overreacting to some foreign substance.  (Bee venom, peanuts, milk, medications etc.) Substances are released by the immune system that causes vasodilation and bronchoconstriction.  The is also an increase in the ability for plasma to leak out of the capillaries (increased capillary permeability) which results in hives (urticaria) on the skin and possible narrowing of the airways.  Treatment involves the use of the EPI-Pen, O2, and transport.

2.       Septic shock is caused by vasodilation which is caused by a severe body wide infection. Usually in the blood stream and major organs. There can also be an increase in capillary permeability like in anaphylaxis.  Treatment involves warmth, O2, leg elevation and transport.

3.       Neurogenic shock is the rarest form of shock.  It is also called spinal shock.  The usual cause is damage to the spinal cord.  This results in interruption of the sympathetic nervous system (Fight or flight). The sympathetic nervous system usually results in vasoconstriction and tachycardia.  If it is interrupted the parasympathetic nervous system will dominate causing vasodilation and bradycardia.  Neurogenic shock is the most difficult of all of the Distributives shocks to diagnosis.  This is because in addition to the other tricky presentations (warm, flushed skin and strong radial pulses) there is also a slow to normal pulse rate.  In the other shocks we expect there to be a tachycardia to compensate for the low perfusion. .  Treatment involves warmth, O2, Leg elevation and transport.  Since there may be paralysis of the muscles of the airway and breathings from the spinal cord injury you may need to maintain the airway (airway adjuncts) and ventilate the patient.

 4.       Psychogenic shock (simple fainting, syncope) results from the vagus nerve being stimulated.  The vagus (10th cranial nerve) is the messenger nerve of the parasympathetic nervous system. When activated it causes a slowing of the pulse and vasodilation resulting in a drop in blood pressure.  This results in less blood to the brain which causes syncope (fainting); the patient becomes unconscious and usually falls supine or prone.  It is now easier for blood to reach the brain then when the patient was standing.  The patient gradually wakes up as the heart rate increases back to normal and the blood vessels go back to normal diameter.  This usually causes the cerebral (brain) hypoperfusion to end. The patient usually has no long-term issues, unless they hurt themselves when they fainted.  EMS can cause Psychogenic Shock to happen by suctioning and /or inserted an OPA too roughly and by pressing to hard when checking a carotid pulse.  Patients can cause this to happen by straining when they go to the bathroom.  Sometimes this happens as a result of stress, bad news, and even the sight of blood. Treatment involves checking the patient for injury, leg elevation, O2, and warmth.  They should be brought to hospital to determine the cause of their syncope.

Obstructive shock is cause by a blockage (obstruction) in a large blood vessel.  Again, there is no loss of blood but rather blood flow through the circulatory system is slowed and may even be stopped.  Common causes include Tension Pneumothorax, Pulmonary Embolism, 3rd trimester pregnant females lying supine, and Cardiac Tamponade.

1.   In a tension pneumothorax pressure builds up in the thoracic cavity outside of the lungs and decreases blood flow through the inferior and superior venae cava. This results in less blood getting back to the heart, which results in less cardiac output.   Usual causes are a puncture or hole to the lung.  This can be caused by penetrating trauma from a bullet, knife or even a broken rib.  Rarely a patient’s lung can burst without trauma; this is called a spontaneous pneumothorax. Signs and symptoms include diminished or absent lung sounds over the injured lung, tracheal deviation away from the injured lung (also called a mediastinal shift, this is usually an x-ray finding), difficulty breathing, tachycardia, and in severe cases hypoperfusion.  In there are any holes between the patient’s shoulders and umbilicus (belly button) they should be sealed with an occlusive (airtight) dressing on 3 sides.  This stops air from being inhaled though the hole on patient’s chest into their thoracic cavity when the patient inhales but allows pressure to vent from the thoracic cavity when the patient exhales. O2 should be administered and the patient should be brought to a trauma center.

2.   Pulmonary Embolisms result in a blockage somewhere in the pulmonary arterial circulation.  This results in lees deoxygenated blood in reaching the lungs.  Patients complain of a sharp pain to their chest and difficulty in breathing. There is no blockage in the airway.  The sensation of shortness of breath (SOB) comes from the restriction of blood flow to the lungs.  Common causes are recent fractures, being bed ridden (confined to a bed), deep vein thrombus (DVT) of the legs.  There is an increased risk in women who smoke and take birth control pills (oral contraceptives).  It could also happen in scuba divers from breathing compressed air while underwater and then coming to the surface too quickly. Management on a BLS level is limited to O2 and rapid transport.

3.   Supine Hypotensive Syndrome. In a third trimester pregnant women who lies supine the weight of the baby may compress the inferior vena cava causing less blood to get back to the heart.  This is usually not an emergency.  EMS can cause this to happen by placing the patient supine as in spinal immobilization.  Treatment is as simple as moving the patient onto their left side or tipping the long board on the left side slightly.

4.   Cardiac Tamponade is when the sac (pericardial sac) surrounding the heart has a buildup of fluid in it.  This fluid can be either blood from trauma or other fluids that build up from infection. It can rarely be caused by a rupture (burst) coronary artery. (This usually fatal) This fluid buildup does not allow the ventricle to fully expand and fill with blood.  This results in decreased cardiac output.  Signs and symptoms may include: In trauma – puncture wounds to chest, jugular vein distention (JVD), diminished or muffled heart sounds (JVD).  Depending on the amount of fluid in the pericardial sac there may be signs and symptoms of shock.  In an infectious (pericarditis) form of Cardiac Tamponade the patient will usually appear ill from an infection.  They will be complaining of pain on their chest, SOB.  There sign may be warm if they have fever or cold if they are in shock.  In severe medical forms of Cardiac Tamponade there can be muffled heart sounds and JVD. In trauma; treatment incudes sealing any holes on the chest (in case there is also a tension pneumothorax), 02, and rapid transport to a trauma center.  In medical; treatment includes O2 and transport.

Ok.  I guess it was not a quick review.

Thanks,

Frank