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distributive shock; vasodilatory shock (multiple organ dysfunction syndrome)

Failure to maintain adequate perfusion of vital organs secondary to, in part, decreased peripheral vascular resistance & loss of capillary integrity with transudation of intravascular fluid. Etiology: 1) sepsis - systemic inflammatory response syndrome (SIRS) 2) anaphylaxis 3) neurogenic a) anesthesia b) vagotonic shock c) spinal shock -trauma 4) pharmacologic agents a) alpha blockers b) beta blockers c) vasodilators 1] nitroprusside 2] ACE inhibitors 3] calcium channel blockers 5) pulmonary predominant form [7] - pneumonia, pulmonary aspiration, lung contusion, near-drowning, COPD exacerbation, hemorrhage, pulmonary embolism 6) hemorrhage & vascular disease [7] Pathology: 1) vasodilation 2) low central venous pressure 3) decreased intravascular volume 4) decreased peripheral vascular resistance 5) loss of capillary integrity 6) transudation of intravascular fluid 7) increased cardiac output (initially) 8) lungs may be predominant, & only, organ system affected until very late [7] Clinical manifestations: 1) mental status deterioration 2) disseminated intravascular coagulation (DIC) 3) acute respiratory distress syndrome (ARDS) 4) dysuria & oliguria 5) lactic acidosis 6) hypotension 7) fever or hypothermia 8) tachycardia Laboratory: 1) serum chemistries a) azotemia b) hyperbilirubinemia c) increased serum transaminases 4) complete blood count (CBC) with peripheral smear a) schistocytes b) leukocytosis with left shift c) leukopenia may be present especially in elderly & immunocompromised d) thrombocytopenia 5) DIC panel (D-dimer, fibrinogen, PT/PTT) 6) arterial blood gas - hypoxemia & respiratory alkalosis with acute respiratory distress syndrome (ARDS) 7) serum lactate, lactic acidosis 8) basic metabolic panel a) metabolic acidosis b) hyperglycemia 9) serum cortisol to assess adrenal insufficiency 10) cosyntropin stimulation test better than serum cortisol Management: 1) intravenous (IV) fluids a) saline b) colloid more expensive than crystalloid (saline) [5] 2) vasopressors a) dopamine 1] 2-5 ug/kg/min to maintain renal perfusion 2] 10-20 ug/kg/min is similar in effect to norepinephrine b) norepinephrine (Levophed) 1] agent generally used when dopamine is inadequate 2] 0.05-2 ug/kg/min c) vasopressin - norepinephrine + vasopressin associated with less atrial fibrillation but not lower mortality [8] d) phenylephrine (Neo-synephrine) 1] almost pure peripheral vasoconstriction 2] 2-10 ug/kg/min e) epinephrine - agent of choice in cardiogenic shock f) dobutamine 1] may actually decrease blood pressure in sepsis due to peripheral vasodilation 2] agent of choice in cardiogenic shock g) synthetic angiotensin II [6] 3) antibiotics 4) surgical drainage of abscesses 5) removal of potential sources of infection a) urethral catheter b) intravenous (IV) catheters c) wound packing d) tampons 6) treatment of anaphylaxis 7) corticosteroids may be of benefit for adrenal insufficiency [3,4,5] a) hydrocortisone 50 mg IV every 6 hours + b) fludrocortisone 50 ug PO QD

Related

anaphylaxis

Specific

neurogenic shock septic shock warm shock

General

shock

References

  1. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 136
  2. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 853-55
  3. Journal Watch 22(18):139, 2002 Annane D et al JAMA 288:862, 2002 Abrahams E & Evans T, JAMA 288:886, 2002
  4. Annane D et al, Effect of low doses of corticosteroids in septic shock patients with or without early acute respiratory distress syndrome Crit Care Med 2006; 34:22 PMID: 16374152
  5. Medical Knowledge Self Assessment Program (MKSAP) 14, 18. American College of Physicians, Philadelphia 2006, 2018.
  6. Khanna A, English SW, Wang XS et al. Angiotensin II for the treatment of vasodilatory shock. N Engl J Med 2017 Aug 3; 377:419. PMID: 28528561
  7. Sinert RH Fast Five Quiz: Refresh Your Knowledge on Key Aspects of Sepsis. Medscape - Jun 07, 2018. https://reference.medscape.com/viewarticle/897550
  8. McIntyre WF, Um KJ, Alhazzani W et al Association of Vasopressin Plus Catecholamine Vasopressors vs Catecholamines Alone With Atrial Fibrillation in Patients With Distributive Shock: A Systematic Review and Meta-analysis. JAMA. 2018 May 8;319(18):1889-1900. Review. PMID: 29801010