Undifferentiated shock

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

Overview

Inadequate perfusion of the tissues
Goal to increase the flow of oxygenated blood to the tissues
MAP<50 in dog studies brain will become ischemic and patients might presents as an altered mental status [1]

Undifferentiated Hypotension Algorithm[2]

Check/manage the following in order:

Algorithm for the Evaluation of Hypotension(By Dr. Ravi Morchi)

Pulse (assess based on patient's age)
- Too slow or too fast (to the point where CO is affected)?
  - If so, HR is likely primary etiology of hypotension
  - Pace or cardiovert
Volume status
- What is the LV end-diastolic volume?
  - Approximated by the IVC diameter or CVP
  - If low:
    - Assess for blood loss versus fluid loss
      - FAST for intra-abdominal bleed
      - US for ruptured AAA
      - Guaiac for GI bleed
      - CXR for hemothorax
    - Treat with IVF and/or pRBCs depending on cause
Contractility
- Is the myocardium severely depressed in its contractile function (cardiogenic shock)?
  - Assess via ultrasound
  - Treat with inotrope (e.g. epinephrine, dopamine
- Is forward flow occurring?
  - Assess for valvular dysfunction (MR, AR)
  - Assess for obstruction (PE, tamponade)
Systemic Vascular Resistance
- Pathologic vasodilation (decreased SVR) suggested by:
  - Warm extremities
  - Bounding pulse
- Treated based on likely etiology of distributive shock (see below)

Differential Diagnosis

Shock

Cardiogenic
- Acute valvular Regurgitation/VSD
- CHF
- Dysrhythmia
- ACS
- Myocardial Contusion
- Myocarditis
- Drug toxicity (e.g. beta blocker, CCB, or bupropion OD)
Obstructive
- Air embolism
- Aortic Stenosis
- Cardiac Tamponade
- PE
- Tension pneumothorax
Distributive
Hypovolemic
- Severe dehydration
- Hemorrhagic shock (traumatic and non-traumatic)

Evaluation

Shock index (SI)[3]

SI = HR / SBP

Used when HR and SBP do not predict severity of hypovolemia in early stages
May be used as secondary triage tool in mass casualty incidents[4]
0.5-0.7 is normal
>0.70-0.75 for occult shock or requirement of life-saving intervention

Consider RUSH to CVS

RUSH exam
Calcium bolus as inotrope
Vasopressin
Steroids, stress-dose, mineralocorticoids

Management

Treat underlying type

Vasopressors

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) [5]	Strong ß1 agonist +inotrope +chronotrope, Weak ß2 agonist +weak vasodilatation )	alpha effect minimal	HR variable effects [6]. Also Increase SA and AV node fx	indicated in decompensated systolic HF, Debut Research 1979[7] 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[8]
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) [9]	mild β1 direct effect	β1 and strong α1,2 effects	Less arrhythmias than Dopamine[8]	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	0.4 U/min	unknown	increases via ADH peptide		should not be titrated due to ischemic effects
Methylene blue[10]	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

External Links

Pediatric Emergency Playbook Podcast: Approach to Shock

References

Plöchl, W, D J Cook, T A Orszulak, and R C Daly. 1998. Critical cerebral perfusion pressure during tepid heart operations in dogs. The Annals of thoracic surgery, no. 1. http://www.ncbi.nlm.nih.gov/pubmed/9692450
Morchi R. Diagnosis Deconstructed: Solving Hypotensionin 30 Seconds. Emergency Medicine News. 2015.
Levitan, Richard M. Fundamentals of Airway Management. 3rd ed. Irving, TX: Emergency Medicine Residents' Association, 2015.
Vassallo J et al. Usefulness of the Shock Index as a secondary triage tool. J R Army Med Corps. 2015 Mar;161(1):53-7.
https://www.ncbi.nlm.nih.gov/pubmed/8449087
Edmund H. Sonnenblick, M.D., William H. Frishman, M.D., and Thierry H. LeJemtel, M.D. Dobutamine: A New Synthetic Cardioactive Sympathetic Amine
De Backer Daniel et al. Comparison of Dopamine and Norepinephrine in the Treatment of Shock. NEJM 363(9). 779-789
https://www.ncbi.nlm.nih.gov/pubmed/15542956
Pasin L et al. Methylene blue as a vasopressor: a meta-analysis of randomised trials. Crit Care Resusc. 2013 Mar;15(1):42-8.

Videos

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[1] Plöchl, W, D J Cook, T A Orszulak, and R C Daly. 1998. Critical cerebral perfusion pressure during tepid heart operations in dogs. The Annals of thoracic surgery, no. 1. http://www.ncbi.nlm.nih.gov/pubmed/9692450

[2] Morchi R. Diagnosis Deconstructed: Solving Hypotensionin 30 Seconds. Emergency Medicine News. 2015.

[3] Levitan, Richard M. Fundamentals of Airway Management. 3rd ed. Irving, TX: Emergency Medicine Residents' Association, 2015.

[4] Vassallo J et al. Usefulness of the Shock Index as a secondary triage tool. J R Army Med Corps. 2015 Mar;161(1):53-7.

[5] ttps://www.ncbi.nlm.nih.gov/pubmed/8449087

[7] Edmund H. Sonnenblick, M.D., William H. Frishman, M.D., and Thierry H. LeJemtel, M.D. Dobutamine: A New Synthetic Cardioactive Sympathetic Amine

[soap2-8] De Backer Daniel et al. Comparison of Dopamine and Norepinephrine in the Treatment of Shock. NEJM 363(9). 779-789

[9] ttps://www.ncbi.nlm.nih.gov/pubmed/15542956

[10] Pasin L et al. Methylene blue as a vasopressor: a meta-analysis of randomised trials. Crit Care Resusc. 2013 Mar;15(1):42-8.