Update on shock management

Dr. Manal Al MaskatiOct, 2011 - Kuwait

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

Thank you

Discussion