324 Approach to shock Flashcards
Shock defined as
clinical syndrome from inadequate tissue perfusion
Clinical shock is usually accompanied by hypotension with a value of
MAP < 60 mmHg in previously normotensive person
MAP value when autoregulation fails
MAP < 60 mmHg
Classification of Shock (7)
Hypovolemic Traumatic Cardiogenic - Intrinsive or compressive Septic - Hyperdynamic or Hypodynamic Neurogenic Hypoadrenal
Early septic shock is also called as
Hyperdynamic septic shock
Late septic shock is also called as
Hypodynamic septic shock
Represents a common end-stage pathophysiologic pathway in various forms of shock
Cell membrane dysfunction
Released in increased response to adrenergic discharge and reduced perfusion of juxtaglomerular apparatus in the kidney.
Renin
Induces the formation of Angiotensin I
Renin
An extremely potent VASOCONSTRICTOR and stimulator of aldosterone and vasopressin
Angiotensin II
Contributes to the maintenance of intravascular volume by enhancing renal tubular reabsorption of Na
Aldosterone
Has a direct action on vascular smooth muscle leading to vasoconstriction; acts on renal tubules to enhance water reabsorption
Vasopressin
Three variables that control stroke volume
pre-load (ventricular filling)
afterload (resistance to ventricular ejection)
Myocardial contractility
Major determinant of tissue perfusion
Cardiac output
CO = SV x HR
Systemic vascular resistance is (increased ? decreased?) in hyperdynamic septic shock and neurogenic shock?
Decreased
Serves as dynamic reservoir for autoinfusion of blood
Venous system
How does septic shock cause heart failure?
Septic shock -> increase pulmonary vascular resistance -> RIGHT heart failure
Renal responses to shock
Conserve salt and water
Decrease renal blood flow
Increase afferent arteriolar resistance
Reduced urine formation (low GFR, increased aldosterone and vasopressin)
This diagnostic test will represent an innefficient cycling of substrate with minimal net energy production / measure of anaerobic metabolism and reflects inadequate tissue perfusion
Plasma lactate/ pyruvate ratio
TXA2 is a potent _
vasoconstrictors
Contributes to pulmonary hypertension and ATN of shock
PGI2 PGE2 are potent _
vasodilators
LTB4
A potent neutrophil chemoattractant and secretagogue that stimulates the formation of ROS.
Produced by activated macrophages, promotes hypotension, lactic acidosis and respiratory failure
Tumor necrosis factor a
PAC / Swan-Ganz catheter did not alter mortality, lenght of stay or cost for ICU. True or false.
True
Serves as an approximation of Left atrial pressure
Pulmonary capillary wedge pressure (PCWP)
Normal cardiac output per L/min
4-8 L/min
Stroke volume per mL /beat
50-100 mL/beat
O2 carrying capacity of hemoglobin
1.39 mL/g
What type of shock?
CVP and PCWP ↓
CO ↓
SVR↑
Hypovolemic
Table 324-4 p. 1748
What type of shock?
CVP and PCWP ↑
CO ↓
SVR↑
Cardiogenic
Table 324-4 p. 1748
What type of shock?
CVP and PCWP ↑↓
CO ↓
SVR↑
Septic shock :Hypodynamic
Table 324-4 p. 1748
What type of shock?
CVP and PCWP ↑↓
CO ↑
SVR (decreased)
Septic shock: Hyperdynamic
Table 324-4 p. 1748
What type of shock?
CVP and PCWP ↓
CO ↓
SVR↓
Neurogenic or Hypoadrenal
(In hypoadrenal shock, SVR may be normal)
Table 324-4 p. 1748
Most common form of shock
Hypovolemic shock
Approximately how many blood loss does the patient have if he/she has mild tachycardia, relatively few external signs?
<20%
Approximately how many bloodloss does the patient have if he/she has become increasingly anxious, tachycardic, with significant postural hypotension and tachycardia? (BP may be normal on supine position)
20-40%
Approximate blood loss if there is hypotension, unstable in supine position, marked tachycardia, oliguria, agitation?
> 40%
Ominous clinical sign in shock
Mental obtundation/ altered sensorium
As the attending physician at the ER, you are considering hypovolemic shock in a patient; what monitoring should you do if patient is unstable, HR >120 and SBP <90?
Central monitoring, do CVP
Upon monitoring of a shock patient, you noted that CVP is <15, what is your next step?
Administer colloid/ blood
HCT <30, CVP >15
Upon monitoring of a shock patient, you noted that CVP is >15, what is your next step?
ECHO and treat appropriately
Differentials: cardiac dysfunction or tamponade
Despite hydration in a Shocky patient, unstable VS and acidosis worsens; what is your next step?
Insert PAC
In monitoring a shocky patient, PCWP is <15, what’s next?
Administer crystalloid, blood
In monitoring a shocky patient, PCWP is 20, what’s next?
Administer 500mL boluses until preload and monitor
In monitoring a shocky patient, PCWP is >20, what’s next?
Give inotropes, do ECHO
Infusion of how many Liters salt solution will restore normal hemodynamic parameters?
2-3 L over 20 - 30 minutes.
True or false. EARLY administration of component therapy during massive transfusion (FFP and platelets) approacing to a ratio of 1:1 of PRBC/ FFP appears to IMPROVE survival.
True.
Pulsus paradoxus defined as
Inspiratory reduction in systolic pressure of >10mmHg
Best inotropic agent for Neurogenic shock.
Norepinephrine or Phenylephrine
Anesthetic agent which may cause hypoadrenal shock.
Etomidate.
Hypoadrenal shock is characterized by (3)
decreased vascular resistance, hypovolemia and reduced cardiac output.
Diagnosis of adrenal insufficiency is established by
ACTH stimulation test.
Treatment for Hypoadrenal shock - empirically
Dexamethasone 4mg IV
Because unlike hydrocortisone - it does not alter your ACTH test
Treatment for hypoadrenal shock - after establishing diagnosis
Hydrocortisone 100mg IV q6
Inotropic with simultaneous afterload reduction - minimizing cardiac -o2 consumption increase as cardiac output increases.
Dobutamine
Inotropic and chronotropic which supports vascular resistance in those whose blood pressure will not tolerate peripheral vascular dilation.
Dopamine
Supports blood pressure through vasoconstriction and increases myocardial oxygen consumption; inotropic without chronotropy.
Norepinephrine.
Being used to increase afterload and may better protect vital organ blood flow and prevent pathologic vasodilation.
Arginine-vasopressin.
