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IM - SHOCK

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tonystep1's version from 2017-08-30 06:43

Basics of Shock

Question Answer
How does shock generally present?Presents with a decrease in BP and malfunction of underperfused organ systems most notably -
a. Lactic acidosis
b. Renal (anuria/oliguria)
c. CNS dysfunction (altered mentation)
What is the initial approach to a patient in shock ?1. A focused history and physical examination to determine possible cause of shock
2. Initial simultaneously stabilize the patient hemodynamically and determine the cause of shock
a. Establish two large-bore venous catheters, a central line, and an arterial line.
b. A fluid bolus (500 to 1 ,000 ml of normal saline or lactated Ringer's solution)
should be given in most cases.
c. Draw blood: CBC , electrolytes, renal function, PT/PTT
d. ECG, CXR
e. Continuous pulse oximetry
f. Vasopressors (dopamine or norepinephrine) may be given if the patient remains
hypotensive despite fluids.
g. If the diagnosis is still in question after the above tests, a pulmonary artery catheter and/or echocardiogram may help in diagnosis
Treatment of Shock?l. ABCs (airway, breathing, and circulation) should be addressed for all patients
in shock.
2. Specific treatment is described below for each type of shock. With the exception
of cardiogenic (and sometimes neurogenic) shock, a generous amount of IV fluid
is usually required to resuscitate the patient. The more advanced the stage of
shock, the greater the fluid (and blood) requirement
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Causes of Shock

Question Answer
Cardiogenic Shockl. After acute MI-most common cause
2. Cardiac tamponade (compression of heart)
3. Tension pneumothorax (compression of heart)
4. Arrhythmias
5. Massive PE leading to RVF
6. Myocardial disease (cardiomyopathies, myocarditis)
Hypovolemic ShockCauses
a. Hemorrhage
• Trauma
• GI bleeding
• Retroperitoneal
b. Nonhemorrhagic
• Voluminous vomiting
• Severe diarrhea
• Severe dehydration for any reason
• Burns
• Third-space losses in bowel obstruction
Septic Shockl . Manifestations related to cause of sepsis (e.g., pneumonia, urinary tract infection,
peritonitis)
Neurogenic ShockCauses include spinal cord injury, severe head injury, spinal anesthesia, pharmacologic
sympathetic blockade
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Clinical Features

Question Answer
Cardiogenic Shockl. Typical findings seen in shock (altered sensorium, pale cool skin, hypotension,
tachycardia, etc.)
2. Engorged neck veins-venous pressure is usually elevated.
3. Pulmonary congestion
Hypovolemic ShockIf the diagnosis is unclear from the patient's vital signs and clinical
picture, a central venous line or a pulmonary artery catheter can give invaluable
information for hemodynamic monitoring: decreased central venous
pressure (CVP)/PCWP, decreased cardiac output, increased SVR
Septic Shockl . Manifestations related to cause of sepsis (e.g., pneumonia, urinary tract infection,
peritonitis)
2. Signs of SIRS (see Box l - 14)
3. Signs of shock (hypotension, oliguria, lactic acidosis)
4. Patient may have a fever or may be hypothermic (hypothermia is more common
in the very young, elderly, debilitated, and immunocompromised).
Neurogenic Shockl. Warm, well-perfused skin
2. Urine output low or normal
3. Bradycardia and hypotension (but tachycardia can occur)
4. Cardiac output normal, SVR low, PCWP low to normal
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Hemodynamic Changes in Hypovolemic Shock

Question Answer
10-15% blood volume lossClass I
20-30% blood volume lossClass II
30-40% blood volume lossClass III
>40% blood volume lossClass IV
Normal pulseClass I
>100 bpmClass II
>120 bpm weak pulseClass III
>140 bpm non palpableClass IV
Normal SBPClass I and Class II
Decreased SBPClass III
Marked Decrease in SBPClass IV
Normal Pulse pressureClass I
Decreased Pulse pressureClass II and Class III
Capillary refill normalClass I
Capillary refill delayedClass II and Class III
Capillary refill absentClass IV
Respiratory rate normalClass I
mild tachypneaClass II
marked tachypneaClass III and Class IV
CNS normalClass I
CNS anxiousClass II
CNS confusedClass III
CNS lethargic, comaClass IV
Urine output normalClass I
20-30 ml/hr UOClass II
20ml/hr UOClass III
Negligible UOClass IV
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Diagnostic results

Question Answer
Cardiogenic Shock ECG findingsS-T segment elevation suggesting acute MI or arrhythmia are the most
common findings.
Cardiogenic Shock EchocardiogramEchocardiogram-can diagnose a variety of mechanical complications of MI, identify
valve disease, estimate EF, look for pericardia! effusion, etc.
Cardiogenic Shock Hemodynamic monitoring with a Swan-Ganz catheter resultsHemodynamic changes include :
a. Decreased Cardiac Output
b. Increased SVR
c. Increased PCWP
Hypovolemic Shock Hemodynamic monitoring with a Swan-Ganz catheter resultsHemodynamic changes include -
a. Decreased Cardiac Output
b. Increased SVR
c. Decreased PCWP
Septic Shockl. essentially a clinical diagnosis.
2. Confirmed by positive blood cultures, but negative cultures are common
Neurogenic Shock Hemodynamic monitoring with a Swan-Ganz catheter resultsHemodynamic changes include:
a. Cardiac Output is decreased
b. SVR is decreased
c. PCWP is decreased
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Treatment and Management of Shock

Question Answer
Cardiogenic Shockl. ABCs
2. Identify and treat underlying cause
a. Acute MI
• Standard treatment with aspirin, heparin (see MI section)
• Aggressive management, i.e. , emergent revascularization with PTCA (or
CABG); has been shown to improve survival.
b. If cardiac tamponade, pericardiocentesis/surgery
c. Surgical correction of valvular abnormalities
d. Treatment of arrhythmias
3. Vasopressors
a. Dopamine is often the initial drug used.
b. Dobutamine may be used in combination with dopamine to further increase
cardiac output.
c. Norepinephrine or phenylephrine may be used in severe or resistant cases.
4. Afterload-reducing agents such as nitroglycerin or nitroprusside are typically not
used initially because they aggravate hypotension. They may be used later with
vasopressors.
5. IV fluids are likely to be harmful if left ventricular pressures are elevated.
6. Recent studies have shown that use of an IABP improves survival in patients with
cardiogenic shock. Effects include:
a. Decreased afterload
b. Increased cardiac output
c. Decreased myocardial oxygen demand
Hypovolemic Shockl. Airway and breathing-patients in severe shock and circulatory collapse generally
require intubation and mechanical ventilation.
2 . Circulation
a. If hemorrhage is the cause, apply direct pressure.
b. IV hydration
• Patients with class I shock usually do not require fluid resuscitation. Patients
with class II shock benefit from fluids, and patients with class Ill and IV
require fluid resuscitation.
• Give fluid bolus followed by continuous infusion and reassess.
• The hemodynamic response to this treatment guides further resuscitative effort.
c. For nonhemorrhagic shock, blood is not necessary. Crystalloid solution with
appropriate electrolyte replacement is adequate.
Septic Shockl . Manifestations related to cause of sepsis (e.g., pneumonia, urinary tract infection,
peritonitis)
2. Signs of SIRS (see Box l - 14)
3. Signs of shock (hypotension, oliguria, lactic acidosis)
4. Patient may have a fever or may be hypothermic (hypothermia is more common
in the very young, elderly, debilitated, and immunocompromised).
Neurogenic Shockl. judicious use of IV fluids as the mainstay of treatment
2. Vasoconstrictors to restore venous tone, but cautiously
3. Supine or Trendelenburg position
4. Maintain body temperature.
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