Shock Flashcards
Shock is inadequate _____ that results from _______ to deliver sufficient ______ to sustain vital organ function.
Tissue perfusion; the failure of the CVS; oxygen and nutrients.
Also called hypoperfusion or circulatory failure
Conductance vessels
Arteries
Resistance vessels
Arterioles
Exhcnage vessels
Capillaries
Capacitance/storage vessels
Veins
Pediatric vs adult patient: Capable of more effective vasoconstriction? What is the consequence of this?
Pediatric; Greater ability to maintain normal blood pressure for a longer time in the presence of shock
Pressure exerted against the walls of the large arteries at the peak of ventricular contraction
Systolic blood pressure
Pressure exerted against the walls of large arteries during ventricular relaxation
Diastolic blood pressure
BP = ___ x ___?
BP = CO x TPR
Important formula for resistance?
Poiseuille’s Law
R = 8nl/(pi)r^4
where n = viscosity, l = length of blood vessel, r = radius of blood vessel
Pulse pressure reflects?
Stroke volume and aortic compliance (SV/AC) `
Narrowed pulse pressure reflects?
Increased TPR, EARLY sign of impending shock
Widened pulse pressure reflects?
Decreased TPR, seen in EARLY septic shock/warm shock/hyperdynamic shock
Early indicators of decreased tissue perfusion
Mottling, cool extremities
Late sign of cardiovascular compromise in a child
Hypotension
What happens to peripheral pulses when cardiac output is decreased?
Also decreased
CO = ___ x ___
CO = HR x SV
Primary method of increasing cardiac output in children?
Increase HR
Why are children dependent on an adequate HR to maintain cardiac output? *Also the rationale behind faster HR in infants –> slower HR as the child grows older
Due to the immaturity of the sympathetic innervation to the ventricles, the heart is unable to increase CO by increasing SV (EDV - ESV). The myocardia are less compliant and less able to generate tension during contraction, limiting SV. As these mature, children become more able to maintain cardiac output by increasing SV.
Circulating blood volume in:
Infants
Children
Adolescents and adults
Infants: 75-80 mL/kg
Children: 70-75 mL/kg
Adolescents and adults: 65-70 mL/kg
Physiologic reserves
Glycogen stores
Glucose requirements
Cardiovascular reserve
Glycogen stores: Less
Glucose requirements: More
Cardiovascular reserve: Greater CIRCULATING blood volume than adults, but less TOTAL blood volume; strong but limited reserves. Decompensate QUICKLY.
Compensated shock
Early shock, inadequate tissue perfusion without hypotension
Body’s sensors and compensatory mechanisms in shock?
Carotid sinus: Baroreceptor; decreased vagal firing rate when BP drops –> increased sympathetic outflow from the CNS –> increased HR, SV, TPR
Medulla, carotid bodies, aortic arch: Chemoreceptors; stimulated mostly by hypoxia, but also by hypercarbia and low pH –> increased RR to blow off CO2
Physical findings in compensated shock?
Narrow pulse pressure, normal SBP Normal to mild increase in HR Mild increase in RR Mild decrease in urine output Mental status changes such as restlessness, irritability, confusion Pale mucous membranes
Hypotensive shock
Occurs when compensatory mechanisms begin to fail
Physical findings in hypotensive shock?
Fall in SBP, DBP; weak central pulses, thready peripheral pulses
Moderate tachycardia, possible dysrhythmias
Moderate increase in RR, possible respiratory fatigue or failure
Marked decrease in urine output
Agitation, lethargy
Pale or cyanotic mucous membranes
What does pulse quality reflect?
Adequacy of peripheral perfusion
What are the four types of shock?
Hypovolemic
Distributive
Cardiogenic
Ostructive
Sudden decrease in the circulating blood volume relative to the capacity of the vascular space
Ex. hemorrhage, plasma loss, fluid and electrolyte loss, endocrine disease
Hypovolemic shock
Distributive shock
Altered vascular tone –> peripheral vasodilation –> increases the size of the vascular space and alters the distribution of the available blood volume –> RELATIVE hypovolemia
Ex. septic shock, anaphylactic shock, neurogenic shock
Cardiogenic shock
Impaired cardiac muscle function leads to decreased cardiac output and inadequate tissue oxygenation
Ex. conduction abnormalities, cardiomyopathy, congenital heart disease
Obstructive
Obstruction to ventricular filling or the outflow of blood from the heart
Ex. tension pneumothorax, massive pulmonary embolus, cardiac tamponade
A 5-year-old child presents with a 3-day history of vomiting and diarrhea. On physical exam, he has poor skin turgor, has cool extremities, and is irritable. What is/are the type/s of shock involved?
Hypovolemic shock due to fluid and electrolyte loss.
A 12-year-old child was involved in a vehicular crash when his bike collided with a speeding car. He was not wearing a helmet, and his head hit the sidewalk when he was thrown off his bike. On PE, he is unresponsive to any kind of stimulus, hypotensive, bradycardic, with irregular respirations. Breath sounds are decreased in the left lung field, no neck vein distension. He has weak peripheral pulses and cool extremities. What type/s of shock is/are involved?
Distributive: Neurogenic, involvement of cervical spine will present with hypotension and bradycardia
Possible hypovolemic: Decreased breath sounds in the left lung field may indicate a hemothorax, and there may also be other sources of internal hemorrhage (abdominal, pelvic fracture)
Four clinical findings to assess dehydration
Abnormal general appearance
Capillary refill >2s
Dry mucous membranes
Absent tears
Priorities in emergent care of a pediatric patient in hypovolemic shock?
Control fluid loss
Restore vascular volume
How do you perform fluid resuscitation in children?
20 cc/kg of isotonic crystalloid solution (ex. pNSS or pLR)
Assess response after EACH BOLUS: increased work of breathing, development of crackles
Generally, 3 mL fluid: 1 mL blood lost
What should be the next steps to consider if the patient does not respond to the initial fluid resuscitation?
Blood transfusion (if hemorrhagic etiology) Use of vasopressors --> when shock remains refractory after 60-80 cc/kg bolus
How is hypoglycemia managed?
Newborn: 5-10 cc/kg D10W
Infants and children: 2-4 cc/kg D25W
Adolescents: 1-2 cc D50W
*In Harriet Lane though, it’s just 2 cc/kg D10 W for newborns
What is the most common type of distributive shock in children?
Septic shock
What are the two stages of septic shock?
Early/warm shock/hyperdynamic phase: Where endotoxins prevent catecholamine-induced vasoconstriction –> peripheral vasodilation –> increased cardiac output to maintain adequate oxygen delivery
Late/cold shock/hypodynamic phase: Inflammatory mediators cause cardiac output to fall –> compensatory increase TPR –> cool extremities (cold shock)
Goals in emergent management of a patient in septic shock?
Restore hemodynamic instability Identify and control infectious organism Limit inflammatory response Support CVS Enhance tissue perfusion Ensure nutritional therapy
Initial therapeutic endpoints in resuscitation of septic shock
Capillary refill <2 s Normal BP for age Normal pulses Warm extremities UO > 1 cc/kg/hr Normal mental status
Other therapeutic considerations in septic shock:
Inotropic support
Mechanical ventilation
Correction of glucose, iCa, other electrolyte abnormalities
Broad-spectrum antibiotic
What pressor is given for warm shock with low BP?
Norepinephrine: 0.1 - 2 mcg/kg/min
What pressor is given for cold shock with normal BP?
Dopamine: 2-20 mcg/kg/min (5-20 in Harriet Lane); this is medium dose, acts more on beta receptors, increases cardiac contractility with little effect on vascular resistance
What is given for cold shock with low BP?
Epinephrine: 0.1 mcg/kg/min
What is the mainstay of treatment in anaphylaxis?
Epinephrine 0.01 mcg/kg of 1:1000 (1 mg/mL), IM at anterolateral thigh
Then support with fluids, salbutamol for bronchospasm, methyprednisolone, diphenhydramine
Goals in the emergent management of cardiogenic shock?
Reduce myocardial oxygen demand Improve preload Reduce afterload Improve contractility Correct dysrhythmias
How do you perform fluid resuscitation in a patient with cardiogenic shock?
Small fluid bolus (5-10 cc/kg) given over 10-20 minutes
When are vasopressors given in those with cardiogenic shock?
Significant hypotension
Unresponsive to fluid resuscitation
Volume overloaded
Intropes with vasoconstrictor effect
Epinephrine, norepinephrine, dopamine (at high doses)
Inotropes with vasodilator effect
Dopamine (at low doses), isoprotenerol, dobutamine, amrinone, milrinone
Possible causes of obstructive shock
Cardiac tamponade
Tension pneumothorax
CHD
Massive pulmonary embolism
Site for needling?
2nd ICS, insert 14- or 16-G needle on top of the 3rd rib, remove needle once there is a popping sound or give, then leave catheter in place
In babies with signs of decompensation due to CHD, what should you administer?
IV infusion of PGE1 (ex. alprostadil) to keep DA patent
In cases where peripheral vascular access cannot be found, what is the next step?
Intraosseus route, in the ff locations:
Proximal tibia: 1-3 cm below and medial to the tibial tuberosity in the flat surface of the tibia
Distal tibia: 1-2 cm proximal to the medial malleolus in the midline
Distal femur: 2-3 cm above femoral condyles in the midline
Head of humerus: Two finger widths below coracoid process and acromion
Remove IO access by?
24 hrs to prevent osteomyelitis
