Circulatory Shock - Hemodynamic profiles

Resuscitative principles:

• ABC and monitoring

• IV access: Large bore, central lines, rapid infusers.

• Fluid resuscitation: IVF crystalloids and colloids. Based on clinical parameters: ABP, UO, cardiac filling pressures, CO, mental status if not sedated or intubated.

  • Crystalloids (NS or RL). Aggressive fluid resuscitation in hypovolemic shock in the absence of signs of CHF.

  • Colloids (albumin 5% - 25%; hetastarch 6%, dextran 40 and dextran 70). Blood products if patient has anemia or active H'ge.

  • Young adequately resuscitated patients should usually tolerate Hcts of 20% - 25%.

  • Older patients with CVS comorbidities may need Hct to be maintained >30%, to optimize O2 to tissues.

• Vasopressors and inotropes: Important role. Need monitoring with ABP and PA cath (Swan-Ganz). Make sure patient is in fluid resuscitation.

  • Dopamine: Stimulates cardiac B1-rcp, peripheral alpha-rcp, and dopaminergic rcp in renal, splanchnic, and other vascular beds.

    • < 5 mcg/kg/min, renal and splanchnic vasodilatory. Increases UO transiently. No renal benefits. Makes UO number look better temporarily.

    • 5 - 10 mcg/kg/min: ▲ CO, by activation of cardiac B1-rcp

    • >10 mcg/kg/min: ▲ BP, by activation of peripheral alpha-rcp.

  • Dobutamine: B1 agonist. Inotropic, reduces afterload by peripheral vasodilation, weak chrontropic (so does not send the heart racing). Good hemdynamic response: ▲ SV with modest increase in HR, unless used in high doses in hypovolemia.

  • Epinephrine: alpha1 and non-selective beta adrenergic activity. Agent of choice in anaphylactic shock. Dose dependent effects.

  • Norepinephrine: alpha1 and beta1-adrenergic activity. Primarily a potent vasoconstrictor.

  • Vasopressin: vasconstrictor mediated by 3 different G-peptide rcps, called V1a, V1b, and V2. Dose: 0.01 - 0.04 U/min

  • Milrinone is a noncatecholamine inhibitor of PDE III that acts as an inotrope and a direct peripheral vasodilator to increase CO.

Circulatory Shock: A process in which blood flow and oxygen delivery to tissues is impaired, resulting in inadequate tissue perfusion, and failure to meet cellular metabolic demands.

SBP <90, MAP <60, hypoperfusion (MS changes, oliguria 0.5 ml/kg/hr; skin mottling), lactic acidosis.

Shock if fluids, and 2 pressors used.

Classification:

• Hypovolemic

  • Causes: Hypovolemic: trauma, GIB, ruptured Aorta, ruptured ectopic preg, burns, NH Pt. on diuretics.

  • Stages of Hypovolemic Shock:

    • Stage 1

      • Up to 15% blood volume loss (750 mL)

      • Compensated by constriction of vascular bed

      • Blood pressure maintained

      • Normal respiratory rate

      • Pallor of the skin

      • Slight anxiety

      • Tachycardia

    • Stage 2

      • 15 - 30% blood volume loss (750 - 1500 mL)

        • Cardiac output cannot be maintained by arterial constriction

        • Tachycardia

        • Increased respiratory rate

        • Blood pressure maintained

        • Increased diastolic pressure

        • Narrow pulse pressure

        • Orthostatic changes

        • Sweating from sympathetic stimulation

        • Mildly anxious/Restless

    • Stage 3

      • 30 - 40% blood volume loss (1500 - 2000 mL)

      • Systolic BP falls to 100 mm Hg or less

      • Classic signs of hypovolemic shock

        • Marked tachycardia > 120/min

        • Marked tachypnea > 30/min

        • Decreased systolic pressure

        • Alteration in mental status

        • Diaphoresis and pallor of skin

    • Stage 4

      • Loss greater than 40% (>2000 mL)

      • Extreme tachycardia with weak pulse

      • Pronounced tachypnea

      • SBP 70 mmHg or less

      • Decreased level of consciousness

      • Skin is sweaty, cool, and extremely pale (moribund)

• Cardiogenic

  • MI, RV infarct, RV failure due to massive PE, septal wall rupture, acute MR, cardiac tamponade, CHF, DCM, arhythmias.

    • AMI results in ~40% loss of viable myocardium. STEMI causes shock.

    • Papillary muscle ruptured VSD - free wall rupture

    • RV infarct: results in hypotension, JVD, no pulmonary edema. R. sided ECG.

    • VSD ( has thrill). Check TTE

    • Drug related: BB, CCB OD; Adriamycin, severe AS, MS; severe tachycardia (AF with RVR); bradyarrhythmia (3° HB)

  • SBP <60, CI: <2, PAOP >18, altered mentation, ▼ UO = MI

  • Obstructive.

    • AS, coarctation of aortia, PE, PTx, air-embolism, tumor embolism. tamponade.

      • Tx cardiac tamponade medically with IVF bolus. Pericardiocentesis.

• Distributive

  • Septic, neurogenic, and anaphylactic

    • Sepsis: when there is evidence of inf + SIRS

    • Severe sepsis: organ dysfunction and hypoperfusion.

    • Septic shock: sepsis with hypotension despite adequate fluid resuscitation 40 - 60 mL/kg, or need of pressors; combined with altered mental status, oliguria, and/or lactic acidosis.

    • Neurogenic

      • Loss of sympathetic tone resulting in hypotension

    • Anaphylactic

      • urticaria, angioedema, hypotension.

    • IV contrast - anaphylactoid shock, cause iodine is not an antigen.

      • Tx; with epi and steroids