Pharmacotherapy of shock

Pharmacotherapy of Shock

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Introduction

Review the current view on etiology, pathophysiology and management of shock with emphasis on pharmacotherapy.


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Topics of Discussion

Pathophysiology of Shock Types of Circulatory Shock Management of Shock

Inotropic Agents Vasodilators


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Shock

Term “choc” – French for “push” or impact was first published in 1743 by the physician LeDran

Belief – symptoms arose from fear or some other form of altered cerebral function

Crile in 1899 showed that replacement of blood volume decreased mortality experimentally


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Determinants of Shock

Inadequate tissue perfusion Sustained loss of effective circulatory

blood volume Breakdown of cellular metabolism

and microcirculatory homeostasis Hypoperfusion of peripheral tissue

that leads to a diminutive transcapillary exchange function

Disproportion between VO2 and DO2


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Hemodynamic States of Shock Hyperdynamic State Hypodynamic State Related to:

Cardiac Output (CO) Systemic Vascular Resistance

(SVR)


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Pathophysiology of Shock Shock develops with inadequate

capillary perfusion by decreased Cardiac Output following heart attack (cardiogenic shock) or blood/volume loss (hypovolemic shock)


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Mediators of Shock

Toxins Endotoxins

Oligo- and polypeptides Complement Factors Opiods TNF, Interleukins

Fatty Acid Derivatives Arachidonic acid metabolites

Varia Calcium


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Main Classes of Shock

Hypovolemic Shock Distributive Shock Cardiogenic Shock Obstructive Shock


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Hypovolemic Shock

Hemorrhagic/Traumatic Dehydrative Burn


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Distributive Shock

Septic Anaphylactic/

Anaphylactoid Neurogenic


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Obstructive Shock

Pulmonary Embolism Cardiac Tamponade Pneumothorax


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Question

Which one of the folowing is the most common cause of severeLactic acidosis (blood lactate concentration >5 mmol/L)?

a. Ethanol intoxicationb. Severe liver diseasec. Circulatory shockd. Ischemic bowele. Acute asthma


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Management of Shock

Shock begins when DO2 to the cells is inadequate to meet metabolic demand

The major therapeutic goals in shock therefore are sufficient tissue perfusion and oxygenation

Early diagnosis remains a major problem


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Pulmonary Artery Catheter Waveforms

Right Atrium Right Ventricle Pulmonary Artery PCWP


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Hemodynamic Characteristics in Different Types of Shock

Type Preload CO PVR SVR

Hemmorrhagic

Anaphylactic

Cardiogenic

Septic (Hyperdynamic)

Septic (Hypodynamic)

/


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QuestionThe wavefrom shown in this figure was observed whileattempting to advance a pulmonary arterial catheter, with the Balloon inflated, from the proximal pulmonatry artery to a “wedged” position.

Which one of the following bv

Which one of the following best explains the terminal portion of the depicted waveform?

a. Pulmonary hypertensionb. Mitral regurgitationc. Severe left ventricular dysfunctiond. Obstruction of the catheter tipe. Pericardial tamponadewww.freelivedoctor.com

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Inotropic Agents and Vasodilators Vasoactive drugs are an important

pharmacologic defense in the treatment of shock.

May be required to support BP in the early stages of shock.

These agents may be needed to: Enhance CO through the use of inotropic

agents Increase SVR through the use of

vasopressors


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Effects of Inotropic Agents and Vasodilators

Epinephrine 0.02 – 0.5

Norepinephrine 0 - 0.05 – 0.5

Dopamine DR 2 -12

Dobutamine 2 - 12

Dopexamine DR 0 - 0.9 - 5

Vasopressin Angiotensin III 5 - 20

Amrinone PDI 5 -10

Drug Receptor CO SVR Dose Range

0 -

(g/kg/min)

1


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Effects of Inotropic Agents and Vasodilators

Nifedipine 0 - 0.5 - 10

Nitroglycerin 0 - 3 - 5

Nitroprusside 0 - 0.5 - 5

Prostacyclin 10 - 40

2

Drug CO SVR Dose Range

(g/kg/min)


Dopamine An endogenous precursor of norepinephrine with

multiple dose-related effects

Low Dose (0.5 - 3 mg/kg/min) 2 and dopaminergic (DR) effects Enhanced blood flow to renal and

splanchnic beds Moderate Dose (5 -10 mg/kg/min)

Positive inotropic effects High Dose (>20 mg/kg/min)

-actions (vasoconstriction)


Pharmacotherapy of shock

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