Undifferentiated shock (peds)

This page is for pediatric patients. For adult patients, see: undifferentiated shock.


Important physiologic differences between pediatric and adult patients

Intravascular volume

  • Newborns: larger total body water compared to adults (75% vs. 60%) with the majority of it being in the extracellular fluid (ECF) (~40% vs. 25%) 
    • Percentage of ECF decreases throughout childhood
  • Large surface area to weight ratio --> younger kids may have more fluid losses from ECF and intravascular space with short illness/environmental exposure decreased preload
    • May present profoundly volume depleted and need more aggressive volume repletion


  • Infants have immature myocardial calcium regulation system, difficulty storing/releasing calcium highly dependent on extracellular calcium for contractility
    • Check iCal, replete calcium earlier, do NOT give CCBs to infants with tachydysrhythmias
  • Stiffer, less compliant myocardium in infants-->increasing heart rate is main compensatory means for increasing BP
    • BUT higher resting heart rate--> less room to go up (e.g. adult with resting heart rate of 60 can double to 120 but a neonate doubling resting heart rate of 120 to 240 is not sustainable)
    • Heavily rely on vasoconstriction, which can further decrease cardiac output
  • Less beta-adrenergic receptors/sympathetic innervations + more dominant parasympathetics --> exaggerated vagal response
  • Hypotension is a ‘’’late’’’ finding in shock!

Clinical Features

  • Signs/symptoms of underlying pathology

Cold shock

  • More common in children than in adults
  • Poor cardiac output due to decreased stroke volume--> tachycardia to compensate
  • Poor peripheral perfusion, increased SVR (vasoconstriction) to compensate-->
    • Skin cold to touch
    • Diminished pulses
    • Mottled skin
    • Cap refill >2s
    • Narrow pulse pressure, eventually hypotension
    • Signs and symptoms of end organ damage as blood shunted to vital organs

Warm shock

  • Hyperdynamic state, with vasodilation and low SVR
  • Results in end organ damage due to shunting of blood away from vital organs to periphery
  • Findings thus include:
    • Tachycardia
    • Wide pulse pressure
    • Bounding peripheral pulses
    • Brisk cap refill

Shock index

Differential Diagnosis

dehydration (from nausea/vomiting, insensible losses due to heat illness_)

Sick Neonate





Pressor Initial Dose Max Dose Cardiac Effect BP Effect Arrhythmias Special Notes
Dobutamine 3-5 mcg/kg/min 5-15 mcg/kg/min (as high as 200) [3] Strong ß1 agonist +inotrope +chronotrope, Weak ß2 agonist +weak vasodilatation ) alpha effect minimal HR variable effects [4]. Also Increase SA and AV node fx indicated in decompensated systolic HF, Debut Research 1979[5] Isoproterenol has most Β2 vasodilatory and Β1 HR effects
Dopamine 2 mcg/kg/min 20-50 mcg/kg/min β1 and NorEpi release α effects if > 20mcg/kg/min Arrhythmogenic from β1 effects More adverse events when used in shock compared to Norepi[6]
Epinepherine 0.1-1 mcg/kg/min + inotropy, + chronotropy
Norepinephrine 0.2 mcg/kg/min 0.2-1.3 mcg/kg/min (5mcg/kg/min) [7] mild β1 direct effect β1 and strong α1,2 effects Less arrhythmias than Dopamine[6] First line for sepsis. Increases MAP with vasoconstriction, increases coronary perfusion pressure, little β2 effects.
Milrinone 50 mcg/kg x 10 min 0.375-75 mcg/kg/min Direct influx of Ca2+ channels Smooth muscle vasodilator PDE Inhibitor which increases Ca2+ uptake by sarcolemma. No venodilatory activity
Phenylephrine 100-180 mcg/min then 40-60 mcg/min 0.4-9 mcg/kg/min Alpha agonist Long half life
Vasopressin Fixed Dose 0.01 to 0.04 U/min unknown increases via ADH peptide should not be titrated due to ischemic effects
Methylene blue[8] IV bolus 2 mg/kg over 15 min 1-2 mg/kg/hour Possible increased inotropy, cardiac use of ATP Inhibits NO mediated peripheral vasodilation Don't use in G6PD deficiency, ARDS, pulmonary hypertension
Medication IV Dose (mcg/kg/min) Concentration
Norepinephrine (Levophed) 0.1-2 mcg/kg/min 8mg in 500mL D5W
Dopamine 2-20 mcg/kg/min 400mg in 250 D5W
Dobutamine 2-20 mcg/kg/min 250mg in 250 mg D5W
Epinephrine 0.1-1 mcg/kg/min 1mg in 250 D5W

Causes of non-response to vasopressors[9]



See Also

External Links


https://rebelem.com/approach-to-the-critically-ill-child-shock/ https://pedemmorsels.com/epinephrine-for-shock/ https://www.chop.edu/clinical-pathway/sepsis-emergent-care-clinical-pathway

  1. Brousseau T, Sharieff GQ. Newborn emergencies: the first 30 days of life. Pediatr Clin North Am. 2006 Feb;53(1):69-84, vi.
  2. Ramaswamy KN1, Singhi S, Jayashree M, Bansal A, Nallasamy K. Double-Blind Randomized Clinical Trial Comparing Dopamine and Epinephrine in Pediatric Fluid-Refractory Hypotensive Septic Shock. Pediatr Crit Care Med. 2016 Sep 23.
  3. https://www.ncbi.nlm.nih.gov/pubmed/8449087
  4. Edmund H. Sonnenblick, M.D., William H. Frishman, M.D., and Thierry H. LeJemtel, M.D. Dobutamine: A New Synthetic Cardioactive Sympathetic Amine
  5. 6.0 6.1 De Backer Daniel et al. Comparison of Dopamine and Norepinephrine in the Treatment of Shock. NEJM 363(9). 779-789
  6. https://www.ncbi.nlm.nih.gov/pubmed/15542956
  7. Pasin L et al. Methylene blue as a vasopressor: a meta-analysis of randomised trials. Crit Care Resusc. 2013 Mar;15(1):42-8.
  8. Anand Swaminathan, "Occult Causes of Non-Response to Vasopressors", REBEL EM blog, July 13, 2017. Available at: https://rebelem.com/occult-causes-of-non-response-to-vasopressors/.