Shock States Flashcards
What is shock?
A complex state of circulatory dysfunction resulting in insufficient oxygen and nutrient delivery to satisfy tissue requirements
Why is early intervention of shock so important?
To interrupt the cycle: decreased blood flow & decreased available oxygen > tissue hypoxia > anaerobic metabolism > metabolic acidosis > irreversible cellular change > cellular death
How are hypotension and shock related?
hypoTN is distinct from shock, but can indicate a late uncompensated shock state
What might cause a dampened wave form on a recently placed arterial line?
1) air in the transducer
2) air in the tubing
3) a clot in the system
What are the clinical signs of shock?
- tachycardia
- poor/reduced perfusion
- prolonged cap refill
- respiratory distress
- poor tone
- poor color
- cold extremities (with normal core temp)
- lethargy
- narrow pulse pressure
- A’s & B’s
- tachypnea
- metabolic acidosis
- weak pulse
How should adequate UOP in the hypoTN neonate be interpreted?
If BP is low, but UOP is WNL, aggressive intervention may not be necessary; renal perfusion is not adversely affected
* exception: infant with septic shock and hyperglycemia with osmotic diuresis
How can a history of birth asphyxia inform your interpretation of hypoTN?
Birth asphyxia may be a/w myocardial dysfunction and may indicate cardiogenic shock
What influences CO?
HR x SV
How does a neonate affect their CO?
Neonates have limited myocardial compliance, and therefore, can increase their output by increasing their HR
What factors negatively affect cardiac output?
- decreased preload
- increased afterload
- decreased myocardial contractility
- electrolyte, mineral or energy imbalances
What is preload?
the end diastolic volume at the beginning of systole (accounted for by the “stretch” of the ventricles caused by volume of blood that returns from venous circulation)
Why does a decreased preload negatively affect your CO?
With decreased venous return, you don’t have enough blood to push out for systemic perfusion
What is afterload?
ventricular pressure at the end of systole (Ejection stops, and systole is complete- because the ventricular pressure developed by the myocardial contraction is less than the arterial pressure. This determines the end-systolic volume (ESV).
Why does increased afterload negatively affect CO?
Increased systemic resistance is difficult for the heart to pump against and therefore, systemic perfusion is limited
Why does decreased myocardial contractility negatively affect CO?
If myocardial ctx is poor or ineffective, systemic perfusion will be inadequate
What electrolytes have a significant on cardiac function?
- calcium
- potassium
- glucose
What are the different types of shock states?
- hypovolemic
- cardiogenic
- distributive
- obstructive
- dissociative
What is included in the term distributive shock?
- septic
- neurogenic
- adrenal
- anaphylactic
What should be considered in differential of shock v. inborn error of metabolism?
Some inborn errors resulting in hypoglycemia or hyperammonemia can mimic the presentation of shock (ex: galactosemia, maple syrup urine disease, etc..)
What is the most common form of shock in the neonate?
Hypovolemic
What is hypovolemic shock the result of?
Inadequate blood volume
What is the etiology of hypovolemia in the neonate?
- antepartum hemorrhage
- postpartum hemorrhage
- non-hemorrhagic losses
What conditions create a hypovolemic state secondary to antepartum hemorrhage?
1) placental hemorrhage (abruptio placentae & placenta previa)
2) TTTS
3) Fetomaternal hemorrhage
4) Difficult delivery (often a/w asphyxia)
5) Umbilical cord injury
6) Birth injuries (spleenic and hepatic rupture)
What conditions create a hypovolemic state secondary to postpartum hemorrhage?
1) coagulation disorders (DIC, coagulopathies)
2) vitamin K deficiency
3) iatrogenic (ex: loss of arterial catheter)
4) adrenal hemorrhage
5) ICH (subdural or subgaleal)
6) pulmonary hemorrhage
7) circumcision wound
What conditions create a hypovolemic state secondary to non-hemorrhagic losses?
1) umbilical cord obstruction (cord, true knot, entanglement)
2) insensible water loss
3) diuretic use
4) sepsis
5) heat stress
6) vomiting/ diarrhea
7) GI abnormalities
8) Dehydration
What increase the risk for a subgaleal hemorrhage?
The likelihood of tearing the emissary vein is increased with a spontaneous, instrument assisted delivery (especially vacuum)
Why are fluid boluses not effective in correcting hypoTN in the septic neonate?
With an infx, endotoxins are released from invading organism affecting the integrity of the capillary wall. The resultant severe capillary leak permits fluid to seep into the interstitium.
What is cardiogenic shock?
Inadequate tissue perfusion secondary to myocardial dysfx and implies primary failure of the heart as a pump
What is the etiology of cardiogenic shock?
1) severe intrapartum or postpartum asphyxia
2) metabolic and/or electrolyte imbalances
3) congenital heart defects
4) cardiomyopathies
5) PPHN and severe RDS
6) PDA
7) Arrhythmias/ dysrhythmias
8) Infectious agents
9) Hypoxemia and/or metabolic acidosis
What metabolic problems can create a state of cardiogenic shock?
Severe hypoglycemia (IDDM), hypocalcemia and academia can cause decreased CO with a decrease in BP.
How do inborn errors and adrenal insufficiency p/w cardiac involvement?
Both states can p/w congestive heart failure, arrhythmias, cardiomyopathy and conduction disturbances
What congenital cardiac defects p/w shock?
Left-sided obstructive lesions are the most common (after PDA closure); other defects can present with shock, but not as commonly
How do hemodynamically significant PDAs in ELBW infants present?
Can cause cardiac failure and hypoTN; may not appreciate a murmur (r/t lack of turbulent blood flow).
What infectious agents are likely to cause myocarditis?
Bacterial, viral and protozoan
How do infectious agents contribute to cardiogenic shock?
Can cause myocarditis > myocardial dysfunction in addition to septic shock
What arrhythmias increase the risk for cardiogenic shock?
Dysrhythmias that cause a decrease in cardiac output, including: SVT, v Tach, v Fib, complete AV block, atrial flutter
What is distributive shock?
There are abnormalities within the vascular beds that can cause blood volume to be distributed inadequately to organs and tissues. There is not a definite volume loss but inappropriate vasodilation, dysfx of the endothelium with a capillary leak, loss of vascular tone, or combo. Bc the intravascular fluid vol is maldistributed, signs of shock present.
How does sepsis create a state of distributive shock?
Endotoxemia occurs , with release of vasodilatory substances and resulting in intravascular hypotension
What organisms are usually responsible for septic shock?
- Gram Neg: E. coli, klebsiella, enterobacter, pseudomonas and proteus
- Can occur with Gram Pos
- Viruses: HSV and enteroviruses
- Fungal infx: candida (primarily in ELBW)
What is a likely consequence of sepsis?
In the presence of bacterial infx, many complicated systemic reactions occur that result in circulatory insufficiency (DIC)
What is the clinical presentation of sepsis as it relates the respiratory system?
increased WOB tachypnea apnea gasping (ominous sign of impending heart failure- think metabolic acidosis) desaturations
What is the clinical presentation of sepsis as it relates the cardiac system?
pulses may be difficult to palpate (compare pulses)
peripheral poor perfusion
prolonged capillary refill
tachycardia > bradycardia
heart size on CXR
enlarged: CHF, myocardial dysfx
compressed: impaired filling & ctx
What is the clinical presentation of sepsis as it relates the integumentary system?
cyanotic
pallor (when you don’t have enough hgb to be cyanotic)
extremities are cool and mottled
What is the clinical presentation of sepsis as it relates to BP?
May be normal or low; late sign of cardiac decompensation; 4 extremity pressures; evaluate pulse pressure
What is the normal pulse pressure for preterm and full term infants?
PT: 15-25
FT: 25-30
What is indicated by a narrow pulse pressure?
- vasoconstriction
- heart failure
- poor CO
- cardiac compression
What is indicated by a widened pulse pressure?
large aortic run-off lesions (PDA, truncus, AV malformations)
What is the clinical presentation of sepsis as it relates the GU system?
Evaluation of UOP will aid in the assessment of end organ perfusion
* red flag: <1mL/kg/h or a declining UOP, especially with there are other signs of hypoperfusion
How should bradycardia with other signs of severe shock be interpreted?
As an impending sign of arrest
What causes a murmur and how should the presence of one be interpreted?
A murmur is caused by turbulent blood flow; pathologic murmurs are typically present with other signs
What labs are indicated for the evaluation of sepsis?
blood gas: hypoxemia, acidosis glucose: may be elevated r/t a catecholamine surge electrolytes: Na & K Ionized Ca: myocardial fx Liver fx: if liver took a hit Renal fx: if kidneys took a hit Coag studies: DIC Blood lactate: met acidosis CBC c diff: evaluate for sepsis BCX: evaluate for sepsis Cardiac enzymes: evaluate for myocardial damage ammonia level: inborn error
What lab should be ordered to evaluate state of fetomaternal hemorrhage?
Kleihauer-Betke tests MOB for fetal erythrocytes
What is the goal of treatment for shock?
Increasing cardiac output > increases tissue perfusion > increases tissue oxygenation > decreases anaerobic metabolism > decreases lactic acid build up > increases pH
What are examples of crystalloid solutions used for volume replacement with hypovolemic shock?
NS, LR
What are the advantages of crystalloid solutions used for volume replacement with hypovolemic shock?
- isotonic
- readily available
- cheap
- no risk of hypersensitvity reactions
- no religious objections
- does not interact with infectious agents
What are the disadvantages of crystalloid solutions used for volume replacement with hypovolemic shock?
has very low molecular weight, and therefore, doesn’t stay in the vascular space long if there is severe capillary leak (lost to the interstitium or intracellular space)
What are solutions used for volume replacement with hypovolemic shock?
crystalloid solutions
colloid solutions
What are examples of colloid solutions used for volume replacement with hypovolemic shock?
blood, albumin and plasma
What are the advantages of colloid solutions used for volume replacement with hypovolemic shock?
preserve high osmotic pressure in the blood, longer acting, helpful with congenital cardiac patients
What are the disadvantages of colloid solutions used for volume replacement with hypovolemic shock?
- not readily available
- expensive
- risk of hypersensitivity reactions
- religious objections
- may interact with infectious agents
Why might an infant with a history of chronic blood loss in a state of severe hypovolemic shock not tolerate volume boluses?
if there has been chronic anemia, the heart may not tolerate rapid volume expansion (ex: congestive heart failure)
What is the treatment goal for a patient in cardiogenic shock?
correct the underlying problems that may negatively affect heart function
Why is the administration of Na HCO3 (4.2%) controversial in the treatment of cardiogenic shock?
because HCO3 converts to CO2 in H2O (make sure they are adequately ventilating); will drive up CO2 more
What medications may be used for the treatment of cardiogenic shock?
- volume expanders
- Na HCO3
- Dopamine Hydrochloride (most common inotrope)
- Dobutamine
- Epi
What is the treatment goal for a patient in septic shock?
involves a combination of hypovolemic and cardiogenic shock therapies
What are some of the causes of bradycardia?
- hypoglycemia
- apnea
- abdominal distension
- increased ICP
- beta blockers
Why should Na HCO3 be carefully considered before administering to a PT baby?
if given too quickly can increase risk of IVH
