EMT - Chapter 15

three; two

Consider ALS transport after a no shock advisory is delivered _____ or _____ shocks were delivered.

1. if vessel size increases, SVR decreases 2. decrease in SVR reduces blood pressure and perfusion

Describe how decreased peripheral vascular resistance can lead to shock

1. if pump fails, regardless of blood volume, delivery of O2 and glucose to cells is decreased 2. can result from a heart attack (MI); disease, old age, or injury can also weaken the heart; mechanical obstruction of movement of blood into the heart may also contribute

Describe how inadequate heart function can lead to shock

1. leads to a decrease in preload which causes stroke volume and cardiac output to fall 2. decrease in cardiac output causes drop in systolic BP 3. drop in systolic BP results in inadequate tissue perfusion

Describe how inadequate vascular volume can lead to shock

1. no one should be in contact with the Pt during the AED's rhythm analysis or its delivery of shocks; say "Clear!" loudly and make sure everyone is clear 2. don't operate AED if machine or Pt is lying in water, the chest is covered with water, or the Pt is extremely diaphoretic 3. if Pt is on metal flooring, catwalks, stretchers, or other item with metal components, ensure that no one else is directly in contact with metal that is touching the Pt before administering shock 4. remove transdermal medication on chest and wipe the site with a towel or gauze before applying the defibrillator pad 5. remove excess chest hair causing the pads to not stick

Describe safety precautions to be taken to protect yourself, other EMS providers, the Pt, and bystanders in resuscitation situations

1. first shock can be delivered to the Pt within 1 minute of the AED's application 2. safer, more effective delivery with hands-free defibrillation 3. more efficient monitoring with sensors that detect loose leads and false or misleading rhythm readings

Describe the advantages of AEDs

1. external adhesive defibrillator pads that attach to the Pt's chest and are connected by cables to the AED 2. may have voice and ECG recorders and memory modules that can provide a record of the operator's use of the device and the AED's functions 3. older models use monophasic waveform while newer use biphasic waveform to deliver less energy while being more effective

Describe the features of AEDs

1. pads transmit the Pt's cardiac rhythm to the AED's circuitry to analyze rhythm and determine if a shock is necessary 2. if a shock is necessary, the device delivers it through the cables via the pads

Describe the functions of AEDs

as time passes, the heart continues to deteriorate from lack of O2 and glucose and undergoes changes that lead to severe myocardial cell ischemia and organ death

Describe the pathophysiology of cardiac arrest

1. patient must be breathing an adequate concentration of O2 with each breath to make sufficient O2 available in alveoli for gas exchange 2. O2 in alveoli must diffuse across the alveolar/capillary membrane to enter capillary and be transported to cells 3. once O2 diffuses across capillary, it has to be transported to the cells, with 1.5-3% dissolved in plasma and the rest bound to Hb 4. once O2 has effectively bonded with Hb, there must be an adequate volume of blood and pressure to move the blood forward through the systemic circulation, enabling it to be delivered to the cells 5. when O2-saturated Hb reaches the cell, the O2 must break its bond, be released from the Hb, and diffuse across the capillary and into the cell

Describe the physiology of maintaining adequate perfusion

follow manufacturer's directions and service recommendations; follow any local protocols

Describe the precautions in the use of AEDs

1. fully automated AEDs - operator attaches device to Pt, pushes a button to turn on the power, and the device does the rest (analyzing, shock) 2. semiautomated AEDs - operator attaches device to Pt, pushes a button to turn on the power, and initiates heart rhythm analysis; once analysis is complete, computer voice indicates whether shock is necessary and, if so, the rescuer pushes the button to deliver the shock

Describe the use of AEDs

1. secure and maintain patent airway 2. establish and maintain adequate ventilation 3. establish and maintain adequate oxygenation via NRB at 15 lpm or via ventilation device 4. do not hyperventilate the shock patient (makes the blood alkalotic, which reduces off-loading of O2 from Hb) 5. stop bleeding ASAP using direct pressure; use tourniquet or hemostatic agents if pressure is not effective 6. splint fractures to reduce bleeding if it doesn't delay transport 7. do not remove impaled object 8. maintain body temp 9. keep Pt in supine position, immobilized if spinal injury suspected 10. apply PASG if required by protocol for suspected pelvic fracture and systolic BP <90 11. rapid transport to the most appropriate medical facility 12. consider ALS intercept for distributive, cardiogenic, obstructive, and nonhemorrhagic categories of shock

Discuss the goals of prehospital management of patients with shock

consider the whole patient: history findings, physical assessment findings, signs or perfusion disturbance, and vital signs 1. obtain a history, paying particular attention to the chief complaint and any other s/s that provide a clue to shock; include info about allergies, medications; pay particular attention to beta blockers and calcium channel blockers which keep the HR from increasing 2. during physical exam, assess for signs of shock such as altered mental status, pale, cool, clammy skin, delayed capillary refill, decreased urine output, weak or absent peripheral pulses, BP, HR, pulse character, RR & TV, skin color/temp/condition, and pulse-ox reading

Explain how to identify the patient who is in a shock state and demonstrate the assessment of patients to identify shock.

1. drop in pressure in the aorta and carotid bodies reduces the tension in the arterial wall, which triggers baroreceptors to send decreased signals to the hypothalamus 2. hypothalamus activates a cascade of organ and gland stimulation and hormone releases in an attempt to increase the BP to restore arterial wall tension 3. body is able to compensate for decrease in pressure 4. BP may appear relatively normal with a possible narrow pulse pressure

Explain the body's compensatory responses to hypoperfusion and how they manifest in the early s/s of shock

AED failure is most commonly attributed to improper maintenance

Explain the importance of AED maintenance in the Chain of Survival of cardiac arrest

...

Explain the importance of EMT training and skills maintenance in the Chain of Survival of cardiac arrest

survival rates of patients in VF SCA decrease with every minute defibrillation is delayed

Explain the importance of early defibrillation in cardiac arrest

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Explain the importance of medical direction in the Chain of Survival of cardiac arrest

1. elderly and newborns don't compensate well and so deteriorate rapidly; geriatric Pt may take meds that prevent some s/s from appearing, so altered mental status and tachypnea may be most profound signs of shock 2. children and young adults compensate well for a long period of time and then decompensate suddenly

Explain the influence of age on the assessment and management of patients with shock

1. lack of O2 in the cell causes a shift from aerobic to anaerobic metabolism 2. results in a drastically lower production of ATP and the creation of lactic acid as a by-product 3. not enough energy available to maintain the Na/K pump 4. sodium is no longer removed from the cell in exchange for potassium 5. K+ and lactic acid leave the cell and begin to collect in the interstitial fluid and enter the blood 6. sodium collects in the cell and attracts water 7. cell swells and eventually ruptures and dies

Explain the pathophysiology of shock, including the consequences of cellular hypoxia and death

helps avoid delivering compressions that are too slow or too shallow

Explain the rationale for the "push hard and push fast" approach to CPR

1. injury to the spinal cord causing loss of sympathetic nervous system stimulation 2. chemical mediators released within the body that cause a systemic dilation of vessels

Give examples of conditions that can lead to decreased peripheral vascular resistance

1. heart attack (MI) 2. disease, old age, or injury weakening the heart 3. mechanical obstruction of movement of blood into the heart may also contribute - pericardial tamponade & tension pneumothorax

Give examples of conditions that can lead to inadequate heart function

1. loss of whole blood, from bleeding 2. loss of plasma volume alone, from diarrhea, burns, excessive urination, increased capillary leakage, and excessive vomiting

Give examples of conditions that can lead to loss of vascular volume

1. patient with valid DNR, POLST, or MOLST 2. patient with injuries that are not compatible with life, such as decapitation 3. obvious death in patients who are in rigor 4. follow local protocol

Identify situations in which resuscitative attempts should be withheld

oxygen; glucose

If the pump fails, regardless of blood volume, delivery of _____ and _____ to cells will be decreased.

cardiac arrest

Managing a patient in __________ is one of the most dynamic situations an EMT can face, calling on almost all of the skills the EMT has learned.

ventricular fibrillation

Patients who have been brought out of ________________ through use of the AED have a high likelihood of slipping back into that state. Monitor these patients closely.

pulse pressure

The blood pressure may appear to be relatively normal in compensatory shock, however, you might also not a narrow ____________.

burn shock

a form of nonhemorrhagic hypovolemic shock resulting from a burn injury

asystole

a heart rhythm indicating absence of any electrical activity in the heart

obstructive shock

a poor perfusion state resulting from a condition that obstructs forward blood flow

septic shock

a type of distributive shock caused by an infection that releases bacteria or toxins into the blood

1. ease of use 2. speed 3. safety 4. effective delivery 5. efficient monitoring

advantages of the AED over manual defibrillation

resuscitation

bringing a patient back from a potential or apparent death

1. from MI 2. from depressed pump function 3. from abnormal rhythm 4. from beta blockers/calcium channel blockers 5. from CHF

causes/types of cardiogenic shock

1. septic 2. neurogenic 3. anaphylactic

causes/types of distributive shock

1. hemorrhagic 2. nonhemorrhagic, including burns

causes/types of hypovolemic shock

1. from tension pneumothorax 2. from pulmonic embolism 3. from pericardial tamponade

causes/types of obstructive shock

1. immediate CPR can double or even triple chance of survival from v-fib-induced sudden cardiac arrest (VF SCA) 2. can be achieved through faster response by EMS and First Responders, more lay CPR providers, and EMS communications personnel providing CPR instructions to a person at the scene

characteristics of early CPR in the chain of survival

usually delivered by paramedics or AEMTs

characteristics of effective advanced life support in the chain of survival

post-resuscitation care will focus on improving patient's chance to recover as nearly as possible

characteristics of integrated post-cardiac arrest care in the chain of survival

1. time from onset of cardiac arrest to the time defibrillation is performed is the most essential factor in increasing prehospital cardiac arrest survival rates 2. chest compressions should be initiated until the AED is available and applied

characteristics of rapid defibrillation in the chain of survival

1. begins 4 minutes after arrest and last through 10 minutes after 2. O2 stores have been exhausted and the myocardial cells shift to anaerobic metabolism, resulting in very little energy production and adds acid production 3. myocardial cells becoming ischemic and in need of O2 and glucose 4. heart not prepared for defibrillation and is not prone to restarting 5. CPR will provide O2 and glucose to the heart and improve chance of successful conversion following defibrillation 6. if Pt in cardiac arrest for >4-5 minutes before arrival and CPR is not being performed, provide 2 minutes CPR before attempting defibrillation to increase chance of conversion to a perfusing rhythm

characteristics of the circulatory phase of cardiac arrest

1. begins immediately upon cardiac arrest through 4 minutes afterward 2. heart still has a good supply of O2 and glucose 3. heart is in good physiological condition for resuscitation 4. CPR started during this time provides continued circulation of additional O2 and glucose and improves the chance of resuscitation even more 5. primary issue in resuscitation is to restore an effective electrical rhythm to generate ventricular contractions 6. heart is prepared for immediate defibrillation and restoration of cardiac rhythm

characteristics of the electrical phase of cardiac arrest

1. begins 10 minutes after cardiac arrest 2. heart starved of O2 and glucose and has a large amount of acid buildup 3. tissues very ischemic and may begin to die 4. chances of survival drop dramatically 5. failure of Na/K pump allows sodium to enter and stay in the cell and attract water, causing the cell to swell and rupture and die, leading to beginning of organ death 6. resuscitation does not typically produce favorable results, due to widespread organ damage leading to continued deterioration after restoration of the pulse 7. limited chances of survival or returning to a near normal level of neurological function

characteristics of the metabolic phase of cardiac arrest

pulseless electrical activity (PEA)

condition in which the heart generates relatively normal electrical rhythms but fails to perfuse the body adequately because of a decreased or absent cardiac output from cardiac muscle failure or blood loss

ventricular fibrillation (VF or V-Fib)

continuous, uncoordinated, chaotic rhythm that does not produce pulses

sudden death

death of a patient within one hour of the onset of signs and symptoms

automated external defibrillator (AED)

device that can analyze the electrical activity or rhythm of a patient's heart and deliver an electrical shock (defibrillation) if appropriate

anaphylactic shock

distributive shock in which chemical mediators cause massive systemic vasodilation and permeable, leaking capillaries

1. restlessness, anxiety, irritability, apprehension 2. slightly increased HR 3. normal or slightly decreased BP 4. pale and cool skin 5. slightly increased RR 6. slightly decreased body temp

early signs of shock (compensatory stage)

defibrillation

electrical shock delivered to help the heart restore a normal rhythm

1. cell, tissue, and organ failure so pervasive and severe that organ death is inevitable 2. microemboli begin to block capillaries throughout the body, leading to lung failure, kidney failure, and other multiple system organ failure (MSOF) 3. clotting factors used up in the formation of microemboli so that substances released to break down the clots are unopposed and lead to widespread uncontrolled bleeding from any wound that was previously clotted

events that occur in the stage of irreversible shock

1. check Pt's airway and provide O2 at 15 lpm by nonrebreather mask or PPV as indicated by Pt's breathing status 2. since many Pts vomit, have suction ready for use and clear airway of any obstructions or fluids 3. secure Pt to stretcher and transfer him to the ambulance; Pt should be placed on backboard so compressions will be more effective if arrest recurs en route to facility 4. consider the most efficient way of getting ACLS to the Pt 5. continue to keep the AED attached to Pt during transport 6. if you have not already done so, perform the secondary assessment en route 7. perform reassessment every 5 minutes

explain assessment and management of a post cardiac-arrest Pt with return of spontaneous circulation

sympathetic nervous system is activated and stimulates the vessels and heart in an attempt to restore BP in the arteries; effects include: 1. increase in heart rate 2. increase in force of ventricular contraction 3. vasoconstriction 4. stimulation of the release of epinephrine and norepinephrine from the adrenal gland

explain how compensatory mechanisms to shock are maintained through direct nerve stimulation

epinephrine and norepinephrine exert a sustained sympathetic effect, including: 1. alpha stimulation results in vasoconstriction in an attempt to increase SVR and BP 2. beta-1 stimulation on the heart causes an increase in HR and contractility; it also speeds the electrical impulse through conduction system to increase cardiac output and, therefore BP 3. beta-2 stimulation on bronchial smooth muscle decreases airway resistance and leads to tremors in skeletal muscle 4. other hormones decrease urine output in an attempt to conserve body fluid while others cause further vasoconstriction, increase HR and contractility

explain how compensatory mechanisms to shock are maintained through release of hormones

chemical mediators are released, which cause massive and systemic vasodilation and cause capillaries to become very permeable, allowing fluid out into the interstitial space and causing a reduction in systemic vascular resistance; loss of fluid also reduces the intravascular volume, causing the preload, stroke volume, cardiac output, systolic BP and perfusion to decrease, resulting in a shock state

explain the mechanisms and pathophysiology of anaphylactic shock, a type of distributive shock

usually caused by CHF, acute myocardial infarction, abnormal cardiac rhythm, or OD on drugs that depress the pumping function of the heart; depressed pump function reduces the force of the left ventricular contraction, stroke volume, cardiac output, systolic BP, and perfusion

explain the mechanisms and pathophysiology of cardiogenic shock

results from a decrease in intravascular volume caused by massive systemic vasodilation and increase in capillary permeability; no actual loss of fluid or blood from the vessels, but a relative reduction in volume

explain the mechanisms and pathophysiology of distributive shock

1. most common form of shock 2. caused from a low blood volume due to blood loss

explain the mechanisms and pathophysiology of hemorrhagic hypovolemic shock

caused by a dysfunction in the ability of O2 to diffuse into the blood, be carried by Hb, off-load at the cell, or be used effectively by the cell for metabolism; can be caused by poisons that interfere with the cell's ability to use O2

explain the mechanisms and pathophysiology of metabolic or respiratory shock

spinal cord injury damages sympathetic nerve fibers that control vessel tone below the level of injury; loss of tone causes vessels to dilate; if the injury is high enough in the spinal cord, enough vessel tone may be lost to cause a drop in systemic vascular resistance, BP, and perfusion to cause shock

explain the mechanisms and pathophysiology of neurogenic shock, a type of distributive shock

form of shock caused by loss of the fluid portion of the blood, such as from burns and dehydration

explain the mechanisms and pathophysiology of nonhemorrhagic hypovolemic shock

the volume is adequate, the pump is working, and the vessels are normal size with adequate resistance, but an obstruction (e.g. clot, pericardial tamponade, or tension pneumothorax) is preventing the blood from moving forward

explain the mechanisms and pathophysiology of obstructive shock

results from infection that releases bacteria or toxins in the blood, causing the vessels throughout the body to dilate and become permeable, allowing fluid to leak out of the vessels into the interstitial space; loss of fluid also reduces the intravascular volume, causing the preload, stroke volume, cardiac output, systolic BP and perfusion to decrease, resulting in a shock state

explain the mechanisms and pathophysiology of septic shock, a type of distributive shock

1. recognition that a person who is unresponsive and has no breathing or no normal breathing has suffered a cardiac arrest 2. immediate activation of the EMS system

factors in the link of the chain of survival known as immediate recognition and activation

ventricular fibrillation; ventricular tachycardia

heart rhythms that indicate defibrillation/shock

asystole; pulseless electrical activity (PEA)

heart rhythms that indicate no defibrillation/shock should be delivered

1. if arrest was witnessed, immediately initiate CPR with chest compressions and apply AED as soon as it is available 2. if arrest unwitnessed, immediately initiate CPR beginning with chest compressions and apply the AED and initiate rhythm analysis after 5 cycles, and then proceed with AED protocol 3. ratio of 30 compressions:2 ventilations 4. compression depth at least 2" 5. if Pt obviously pregnant or in 3rd trimester, use manual maneuver to displace the uterus laterally while Pt is supine; if not successful, tilt Pt no more than 30° by placing padding under the right side of the backboard

identify appropriate assessment and resuscitative techniques, including AED use, ventilation, and CPR for adults

1. use CAB intervention approach 2. ratio of 30:2 for 1 rescuer and 15:2 with 2 rescuers 3. compression depth ~2" or 1/3 the anterior-posterior chest diameter 4. apply AED after 5 cycles of CPR (~2 min), unless rhythm disturbance is suspected such as a sudden collapse at a sporting event; if rhythm disturbance is suspected, begin CPR with compressions and apply AED as soon as available 5. HR >60 with absent ventilations, begin PPV at 12-20/min; HR<60 with signs of poor perfusion after ventilation and oxygenation have been delivered, initiate CPR beginning with compressions

identify appropriate assessment and resuscitative techniques, including AED use, ventilation, and CPR for children 1-8 years

1. use CAB intervention approach 2. ratio of 30 compressions:2 ventilations for 1 rescuer and 15 compressions:2 ventilations with 2 rescuers 3. compression depth ~1 1/2" or 1/3 the anterior-posterior chest diameter 4. apply AED after 5 cycles of CPR (~2 min) 5. manual defibrillation preferred in Pts <1 year if ALS is available; if not, use AED with pediatric dose-attenuator, if available 6. HR >60 with absent ventilations, begin PPV at 12-20/min; HR<60 with signs of poor perfusion after ventilation and oxygenation have been delivered, initiate CPR beginning with chest compressions

identify appropriate assessment and resuscitative techniques, including AED use, ventilation, and CPR for infants <1 year

shock

insufficient supply of oxygen and other nutrients to body cells resulting from inadequate circulation of blood; aka hypoperfusion

hypoperfusion

insufficient supply of oxygen and other nutrients to body cells resulting from inadequate circulation of blood; aka shock

1. listlessness, apathy, confusion, slowed speech 2. rapid HR 3. slowed, irregular, weak, thread pulse 4. decreased BP 5. cold, clammy, pale skin 6. rapid breathing 7. severely decreased body temp 8. confusion and incoherent, slurred speech, possibly unconsciousness 9. depressed or absent reflexes 10. decreased BP with diastolic pressure reaching zero 11. dilated pupils slow to react 12. slow, shallow, irregular respirations

late signs of shock (decompensatory stage); if appropriate care not given, will reach the stage of irreversible shock and death

hypovolemic; cardiogenic; metabolic/respiratory; obstructive; distributive

list the overall categories of shock

1. electrical phase 2. circulatory phase 3. metabolic phase

phases of cardiac arrest

cardiogenic shock

poor perfusion resulting from an ineffective pump function of the heart

ventricular tachycardia (VT or V-Tach)

rapid heart rhythm that may or may not produce a pulse; usually too fast to adequately perfuse body organs

1. immediate recognition of cardiac arrest and activation of EMS system 2. early CPR 3. rapid defibrillation 4. effective ALS 5. integrated post-cardiac arrest care

sequence of events in the AHA's chain of survival

chain of survival

series of interventions - early access, CPR, defibrillation, and ACLS - that provides the best chance for successful cardiac resuscitation

distributive shock

shock associated with a decrease in intravascular volume caused by massive systemic vasodilation and an increase in the capillary permeability

nonhemorrhagic hypovolemic shock

shock caused by loss of fluid from the intravascular space with red blood cells and hemoglobin remaining withint the vessels

hypovolemic shock

shock caused by the loss of blood or fluid from the intravascular space resulting in a low blood volume

hemorrhagic hypovolemic shock

shock from the loss of whole blood from the intravascular space

return of spontaneous circulation (ROSC)

spontaneous pulse return during resuscitation

irreversible shock

stage in which interventions cannot prevent the advance of shock to death

compensatory shock

stage of shock in which a cascade of organ and gland stimulation and hormones increases blood pressure, restores arterial wall tension, and maintains a near normal blood pressure and perfusion of vital organs

decompensatory shock

stage of shock in which the body's compensatory mechanisms are no longer able to maintain a blood pressure and perfusion of the vital organs

survival

term applied to a patient who survives cardiac arrest to be discharged from the hospital

cardiac arrest

the cessation of cardiac function with the patient displaying no pulse, no breathing, and unresponsiveness

1. decreased preload 2. decreased stroke volume 3. decreased cardiac output

three events that result from loss of blood volume

total downtime

time from cardiac arrest until delivery to the emergency dept

downtime

time from cardiac arrest until effective CPR

neurogenic shock

type of distributive shock that results from massive vasodilation; also called vasogenic shock