Leanna R. Miller, RN, MN, CCRN,-CMC, PCCN-CSC CEN, CNRN, CMSRN, NP Education Specialist LRM Consulting Nashville, TN

Definition  tissue perfusion that is inadequate to maintain normal metabolic and nutritional functions  potentially fatal if not identified & treated

Introduction  12% to 18% of patients presenting initially in severe shock have increased mortality or morbidity related to secondary organ failure

Clinical Signs of Shock Preterminal Stages  severe hypotension  agonal respirations  thready pulse  tachy or bradydysrhythmias

Shock Index HR / systolic blood pressure  HR / systolic blood pressure  inversely related to LVSW  abnormal > 0.9  application: persistently abnormal shock index in patient with normal VS suggests need for more invasive monitoring Rady (1992) Resuscitation 23:

 most important feature to the care of a critically ill patient is delivery of oxygen to the cells

CO X CaO 2 X 10  CO X CaO 2 X 10  CaO 2 = Hgb x SaO 2 x 1.38  Normal mL/min  DO 2 I = mL/min/m 2

oxygen consumption  CO x (SaO 2 - SvO 2 ) Hgb x 1.38 x 10  VO 2 = mL/min  VO 2 I = mL/min/m 2

 normally VO 2 is 25% of DO 2

 SvO 2 SaO 2 SaO 2 Hgb Hgb CO CO VO 2 VO 2

 amount of oxygen extracted from blood as it passes through the tissues  (CaO 2 - CvO 2 )/ CaO 2  values > 0.30 abnormal  > 0.35 serious  normal 22% to 27%

 > 0.35 increased VO 2 increased VO 2 decreased DO 2 decreased DO 2 both both

 CI 4.5 L/min/m 2  DO 2 I 600 L/min/m 2  VO 2 I 170 mL/min/m 2

 inadequate pulmonary gas exchange  inadequate oxygen carrying capacity  inadequate CO

 conditions and activities that alter demand and consumption

critically low DO 2  critically low DO 2  vasodilated state  vaso-obstructed state   diffusion distances   affinity of Hgb for O 2

 increased extraction  once extraction maximized – consumption is dependent on delivery  demand > consumption = O 2 debt

 may be  or normal in presence of hypoxia  not reliable reflection of tissue hypoxia  reliable indicator of tissue perfusion

 arterial more precise  normal < 1 mEq/L  > mEq/L significant hypoperfusion  will decrease % / hr when appropriate therapy used

 pHi  early warning of inadequate splanchnic tissue oxygenation  low pH = poor prognosis (consistently < 7.3)

Lab Studies  Normal value: - 2 to + 2  reflects the extent to which the body buffers have been exhausted  rapidity of normalizing base deficit decreases morbidity & mortality

Most Reliable Perfusion Markers  Serum lactate  Base deficit

StO 2 n near infrared light illuminates tissue n light scatters and is absorbed differently by oxygenated and deoxygenated hemoglobin in the microcirculation n light returns to sensor and is analyzed and displayed as % StO 2

StO 2

 volume  inotropes  vasodilators  assess peripheral circulation

 Identify potentially inadequate DO 2 states clinical evidence of shock clinical evidence of shock SvO 2 < 50% SvO 2 < 50% O 2 ER > 30% O 2 ER > 30%

 Identify pathological flow dependency state –  DO 2 with fluids or inotrope – recalculate VO 2 – VO 2  > L/m 2

 ensure accurate parameters  index to body size  eliminate sources of error  use parameters with < 5-10% variance

 calculate actual VO 2  estimate potential VO 2 (look at factors that  demand)

 delivery needs to  by at least same by at least same percentage as demand percentage as demand

 O 2 demands are  30-50%  triggers systemic inflammatory response

 Hgb/Hct < 11/33 is associated with delivery- dependence   mortality if therapeutic targets reached < hours

 CI > 4.5  DOI  VOI 2 170

 46 - year old male motor vehicle crash injuries: aortic disruption, severe bilateral pulmonary contusions, bilateral rib fractures, splenic fracture traumatic shock due to injuries

Which hemodynamic findings are abnormal? Which hemodynamic findings are abnormal?

HR 67 BP 122/64/82 RAP / PAOP 10/11 CI 4.6 PVRI / SVRI 143/317 RVSWI / LVSWI 17/61 PAP 46/22/32

EDV / EDVI237/107 EF 60% O 2 ER 26.8 SvO 2.74 DO 2 / DO 2 I 1603/722 VO 2 / VO 2 I 430/194

ABGs (.40 FiO 2 ) pH 7.31 pCO 2 42 pO SaO 2.99 HCO SvO 2 74% P/F ratio 314.0

Lab Values Hgb 12.1 Hct 31.0 Sodium 139 Chloride 112 Magnesium 1.7 Lactate 5.1 Base Deficit -5.1

What is the underlying pathophysiology? What is the underlying pathophysiology?

What is are the priority interventions? What is are the priority interventions?

n 33 yr with GSW to chest n 4 units of PRBC due to Hct of 27 n SVO 2 – 70 after blood administration n StO 2 – 80% n Lactate 1.2 n Does he need further treatment ? StO 2 and Hemodynamic Monitoring