Objectives Briefing about pathophysiology of shock. Initial steps of pt’s stabilization. Work-up in A/E. Some important procedures ,which
considered beneficial for shock management.
How ?When? and What ? medications are important to know to manage any type of shock.
Pathophysiology Shock inadequate delivery of
substrates and oxygen to meet the metabolic needs of tissues.
Cell anaerobic metabolic pathway accumulation of lactic acid.
Hypoxic-ischemic injury widespread cellular death multiple system organ failure death.
Pathophysiology DO2 (mL O2/min) =
CaO2 (mL O2/L blood) X CO (L/min)
DO2 amount of oxygen delivered to body tissues/ min.
CaO2 oxygen-carrying capacity depends on: Hemoglobin (Hb) content Arterial oxygen saturation
(SaO2). CO cardiac output depends
on: stroke volume (SV) heart rate (HR).
CO = HR (beats/min) X SV (mL/beat)
SV stroke volume depends on: Preload Afterload Contractility
BP = CO X SVR
Treatment ABC Non-invasive monitors Abx in septic shock with empiric coverage
Neonates : combination of ampicillin and gentamicin.
Older infants and children: third-generation cephalosporin,with vancomycin if indicated.
Baseline work-up
Treatment Volume expansion
Children with hypovolemic shock receive appropriate aggressive fluid resuscitation within the 1st hr of resuscitation optimal chance of survival and
recovery.
Place 2 large-bore IV catheters or IO access.
Administer 20 mL/kg isotonic crystalloid infusion re-evaluate administer additional 20 mL/kg if needed.
If > 2-3 of 20-mL/kg volumes crystalloid given to patient at risk for hemorrhage packed RBCs.
In study of survival in children with septic shock children received an average 65 mL/kg of volume in 1st hr had statistically increased chance of survival compared with other groups received < 40 mL/kg in 1st hr.
Exception to repetitive volume resuscitation cardiogenic shock.
Work-Up
CBC count
Hb oxygen-carrying capacity.
or white cell count septic shock.
Thrombocytopenia bleeding disorder or DIC.
Acid-base status
Shock produces lactic acid metabolic
acidosis with anion gap.
Diarrhea leads to direct bicarbonate loss.
Measurement of serum lactate level
distinguish bicarbonate loss from lactic
acidosis due to shock.
Work-Up
Complete metabolic panel
Hypernatremia intravascular volume
contraction hypovolemic shock.
serum carbon dioxide metabolic acidosis.
Hypovolemia BUN and creatine levels.
liver enzymes hypoxic-ischemic damage
to liver.
Work-Up
B-type natriuretic peptide
BNP : hormone produced by ventricular
myocytes in response to myocardial wall
stress.
Plasma BNP levels (adult and pediatric
studies) in sepsis and congestive heart
failure with cardiogenic shock.
Elevated levels of BNP myocardial stress,
and improvement in cardiac function
normalization of BNP levels.
Work-Up
Imaging Studies
Never delay resuscitation of patient in shock
CXR
Cardiomegaly in cardiogenic shock.
Small heart size in hypovolemic shock .
ARDS from pneumonia and sepsis.
Work-Up
Other Tests
Near-infrared spectroscopy (NIRS)
Values correlate with venous oxygen saturations noninvasive measurements of increased or decreased tissue oxygen saturation (adequate or inadequate DO2 ).
Cardiac index
CO divided by body surface area (BSA)
Normal CI is 3.5-5.5 L/min/m2
Cardiac index invasive or noninvasive measurements (Doppler echocardiography, or classic pulmonary artery catheter).
Work-Up
Procedures Mixed Venous Oxygen Saturation (SvO2)
Blood gas from central venous catheter or Swan-Ganz catheter.
In patient with normal SaO2 (90-100%) SvO2 70-80%.
Tissues extract 28-33% of oxygen delivered to them.
If oxygen extraction difference > 33% poor tissue perfusion state of shock.
If oxygen extraction difference < 25% oxygenated blood shunting distributive shock.
Procedures Central venous pressure and pulmonary
capillary wedge pressure
Low CVP or PCWP inadequate
intravascular volume.
Normal CVP 1-3 cm H2 O.
Pressures > 10 cm H2 O volume overload
or poor right-sided heart function
PCWP of 12-18 cm H2o good perfusion.
Medications Dextrose administration often necessary
If glucose level low 0.5-1 g/kg IV Dextrose.
Shock with documented hypocalcemia, or caused by arrhythmias (hyperkalemia, hypermagnesemia, or calcium channel blocker toxicity) calcium therapy.
Recommended dose is 10-20 mg/kg (0.1-0.2 mL/kg of calcium chloride 10%) IV at infusion rate 100 mg/min.
Sodium bicarbonate use in treatment of
shock is controversial.
No better effect on
Ability to defibrillate
DO2
Survival rates in shock and cardiac arrest
Medications
In patients with persistent shock or ongoing bicarbonate loss (eg, severe diarrhea) careful replacement of bicarbonate.
HCO3- (mEq) = Base deficit X patient's
weight (in kg) X 0.3
Half of calculated bicarbonate deficit administered initially.
OR
0.5-1 mEq/kg/dose IV infused over 1-2 minutes.
Medications
Vasopressors/inotropic agents
Increase myocardial contractility + variable effects on peripheral vascular resistance
Dopamine
o 1st inotrope fluid-refractory septic shock .
o Low dose (2-5 mcg/kg/min IV) vasodilatory effect on end-organ perfusion .
o Intermediate dose (5-10 mcg/kg/min IV) improves myocardial contractility + CO + enhancing conduction.
o Higher dose (10-20 mcg/kg/min IV ) increases peripheral vasoconstriction + BP.
Medications
Dobutamine
o Good for cardiogenic shock.
o Increases cardiac contractility + peripheral vasodilation (afterload and improve tissue perfusion).
o Less likely to precipitate ventricular dysrhythmias than epinephrine.
o Dose begins with 5 mcg/kg/min IV , gradually increased to 20 mcg/kg/min IV.
Medications
Epinephrine
o For fluid refractory dopamine resistant, non-vasodilatory (cold) shock.
o Increases myocardial contractility + peripheral vasoconstriction.
o Risk of ventricular dysrhythmias + extremities ischemia
o Dose : 0.1 mcg/kg/min IV , titrated upward according to effect and adverse effects.
o Severe cases 2-3 mcg/kg/min IV or higher.
Medications
Norepinephrine
o For fluid-refractory, dopamine-resistant vasodilatory (warm) shock.
o Increases peripheral vasoconstriction BP.
o Best pressor agent increases BP in shock persists after adequate fluid replacement.
o Dose : 0.1 mcg/kg/min IV ,titrated upward according to effect and adverse effects.
Medications
Phosphodiesterase Enzyme Inhibitor
Inamrinone + milrinone
o Useful for shock with adequate intravascular volume, but need increased cardiac contractility and better peripheral perfusion ( compensated shock with poor peripheral perfusion).
o Improve cardiac inotropy + peripheral vasodilation.
o Phosphodiesterase inhibitor used together with catecholamines increase myocardial contractility + reducing systemic vascular resistance and afterload.
Medications
Inamrinone + milrinone
o Inamrinone : loading dose of 0.75 mg/kg IV over 2-3 minutes followed by continuous IV infusion of 5-10 mcg/kg/min.
o Milrinone : loading dose of 25-50 mcg/kg over 10 minutes, followed by continuous IV infusion of 0.375-0.75 mcg/kg/min.
o Adverse effects: arrhythmias + thrombocytopenia
Medications
Prostaglandin E1
o Neonates with shock (large liver, enlarged cardiac silhouette, or heart murmur) obstructive shock(PDA closure) .
o PDA allow sufficient systemic blood flow to bypass obstructive lesion.
o PGE1 maintains patency of PDA.
o Dose 0.05-0.1 mcg/kg/min IV as continuous infusion.
o Adverse effects : fever, apnea, or hypotension due to vasodilation.
Medications
Corticosteroid
o Use of corticosteroids in septic shock controversial
o Adrenocortical failure or infarction (Waterhouse-Friderichsen syndrome) cardiovascular failure + hyporesponsiveness to catecholamines.
o Initiation of stress-dose hydrocortisone (50-100 mg/m2/d IV), may be lifesaving.
o A serum cortisol level drawn prior to first dose of corticosteroids serum cortisol level low replacement doses.
Medications
Corticosteroid
o Study of adult patients with septic shock survived 48 hours ,dependent on inotropic agents showed some benefit when treated with supraphysiologic doses of corticosteroids.
o Patients developed adrenal insufficiency 1-2 mg/kg hydrocortisone IV every 6 hours OR 50 mg/kg bolus followed by same amount infused over 24 hours.
o Therapy continued for patients absolute baseline cortisol level < 20 mcg/dL.
Medications
Initial steps of stabilization make
tremendous difference in pts survival.
In non-cardiogenic shock fluid fluid
fluid.
Early Abx improved survival in septic shock.
Arrange for ICU bed.
Don’t forget the Team-Work management.
Take Home Message