Lecture 3: General Information About Shock

SHOCK GENERAL PRINCIPLES

SHOCK • syndrome – sum of signs and symptoms induced by multiples causes • multiples causes – the same clinical picture • common pathophysiological pathway – cause primary pathophysiologogical event (specific for each type of shock) compensatory phenomena decompensatory phenomena death • causative event - great degree of severity • without treatment causes death • shock treatment - the treatment of the cause + the interruption of the pathophysiological events

SHOCK DEFINITION clinical syndrome induced by various causes and characterized by the reduction of the effective tissue perfusion pressure and generalized cellular dysfunction. Effective tissue perfusion pressure = tissue perfusion pressure which ensures adequate oxygen tissues delivery which matches tissue oxygen consumption. • Systemic disease (affects all the organs and tissues) • Variable clinical picture ( depends on: – the severity of perfusion deficit – causative factor – the moment of temporal evolution – preexisting diseases

• The treatment aims the interruption of the pathophysiological cascade + causative treatment

SHOCK Tissue hypoperfusion – key concept – inadequate delivery of oxygen and nutrients Clinical syndrome characterized by the generalized disturbance of the balance between tissue oxygen delivery and tissue oxygen consumption with the occurrence of the anaerobic metabolism and organ and system dysfunction. – oxygen debt – anaerobic metabolism – metabolic acidosis

SHOCK CLASIFICATION (Weil and Shubin) • Hypovolemic shock – reduction of effective circulating blood volume (hypovolemia)

• Cardiogenic shock – reduction of cardiac output induced by primary cardiac causes

• Extracardiac obstructive shock – reduction of cardiac output induced by extracardiac primary causes

• Distributive shock – maldistribution of blood flow caused by vasodilation

PATHOPHYSIOLOGY Initial event: ↓ blood circulating volume → hypovolemic shock ↓ cardiac output → cardiogenic shock – maldistribution of blood flow → septic shock Initial event → compensatory phenomena → decompensatory phenomena → cascade of pathophysiological events which depend on: – natural evolution of the disease→ continuously worsening process – therapeutic intervention→ interruption of the cascade + new problems

SIRS

cause of shock – sepsis effect of treatment – ischemia-reperfusion phenomena

PATHOPHYSIOLOGY hypovolemia ↓ cardiac output maldistribution of blood flow

can coexist în any type of shock

any type of shock can evolve from one form to another

CLINICAL DIAGNOSIS OF SHOCK Clinical picture varies with : – – – – –

Type of shock Severity of shock Causative factor Preexisting conditions Anterior therapeutic interventions

COMMON CLINICAL SIGNS OF SHOCK STATES – – – – –

Tachycardia Tachypnea Arterial hypotension Altered mental status Oliguria

SHOCK CLINICAL DIFFERENTIAL DIAGNOSIS OF SHOCK STATES: We have to answer two questions : – Is cardiac output decreased or increased? – Is the heart empty or too full?

BP = CO x SVR

CLINICAL DIFERENTIAL DIAGNOSIS OF SHOCK STATES: We have to answer the question:

Is cardiac output decreased or increased?  cardiac output is increased (hyperdynamic shock): – warm extremities – large pulse wave – good color return to the nail bed – full peripheral veins – reduced diastolic pressure

 cardiac output is decreased (hypodynamic shock): – cold extremities – small pulse wave – delayed return of color to the nail bed – collapsed peripheral veins

CLINICAL DIFERENTIAL DIAGNOSIS OF SHOCK STATES: We have to answer the question?: Is the heart too full or empty?  Is the heart too full? -

turgescent jugular veins dyspnea, pulmonary rales, cyanosis precordial pain abnormal heart sounds and cardiac murmmurs ECG abnormalities

 Is the heart empty? -

collapsed jugular veins intense thirst pallor history or clinical signs of hemorrhagic or non-hemorrhagic losses

HEMODYNAMIC EVALUATION OF THE SHOCK STATE • • • • • • • •

Arterial blood pressure Heart rate ECG Pulse oximetry Central venous pressure Cardiac output and PAOP SvO2 Transthoracic and transesophageal echocardiography

HEMODYNAMIC EVALUATION OF THE SHOCK STATE • ARTERIAL BLOOD PRESSURE – Noninvasive nonautomatic measurement • palpation method • auscultation method

– Noninvasive automatic measurement Advantages: • noninvasive method (without risks) • automatic method (saves time, frees personnel for other tasks) • measurement at setted time intervals Disadvantage: • no accuracy in case of hypotension • long lasting measurement – difficult to record sudden variations of blood pressure • may cause superior limb edema ( frequent cuff inflation)

– Invasive measurement • arterial catheter Advantages: • real time measurement of blood pressure • accurate measurement for both elevated and reduced values of arterial blood pressure • allows repeated samples of arterial blood for blood gases analysis • allows blood samples for other laboratory analysis (no venous puncture) Disadvantages: • risk of complications (ischemia, trombosis, hemorrhage) • requires experience( arterial puncture) • requires medical equipment

HEMODYNAMIC EVALUATION OF THE SHOCK STATE

HEART RATE – Measurement methods: • Manually - frequency of pulse waves (ATTENTION in case of atrial fibrillation) • pulse oximetry • ECG monitoring

HEMODYNAMIC EVALUATION OF THE SHOCK STATE ELECTROCARDIOGRAPHY – Allows: • Real time heart rate measurement • Detection and diagnosis of cardiac arrhythmias and response to treatment • Detection of myocardial ischemia (ECG abnormalities) and the response to treatment

HEMODYNAMIC EVALUATION OF THE SHOCK STATE PULSE OXIMETRY – Allows measurement of Sa02 in peripheral arterial blood – The principle of measurement : red light absorption is different in oxyhemoglobin and reduced hemoglobin – Equipment with source of red light and sensor – Is applied on the thin peripheral tissues , which permit transillumination: • Digital (finger or toe) probes • Ear probes • Nasal probes

– Advantages: • • • • •

Allows continuous non-invasive evaluation of the arterial blood oxygenation Allows heart rate measurement Allows detection of arrhythmias (without diagnosis) Allows evaluation of the pulse wave amplitude Allows gross evaluation of peripheral perfusion

– Disadvantages: • • • •

The measurement unreliable in case of painted nails Frequent artefacts caused by movements Low accuracy of blood oxygenation evaluation Measurement impossible when tissue perfusion pressure is very low

HEMODYNAMIC EVALUATION OF THE SHOCK STATE CENTRAL VENOUS PRESSURE – central venous catheter (the tip of catheter in superior vena cava) – catheter introduced through internal jugular, external, subclavian, axilary, brachial vein

Methods of measurement: • water column method • automatic method (transducer)

– Advantages: • allows monitoring of CVP (venous return); evaluates heart filling (right ventricle) • allows monitoring of treatment response

– Disadvantages: • risks of central venous catheterization (pneumothorax, cervical or mediastinal hematoma, infection, gas embolism) • requires special equipment (for automatic measurement) • for elevated values of CVP, inaccurate evaluation of right heart filling

HEMODYNAMIC MONITORING OF THE SHOCK STATE PULMONARY ARTERY CATHETER – Catheter ~ 1m long introduced through a central vein the tip of the catheter in one pulmonary artery branch – Catheter introduced through internal jugular or subclavian vein – passes through superior vena cava, right atrium, right ventricle, common pulmonary artery, one principal branch of pulmonary artery, ramifications of pulmonary artery

MONITORING

MONITORING

MONITORING

MONITORING

MONITORING

MONITORING

PULMONARY ARTERY CATHETER – Hemodynamic data: • Measured parameters: – – – – –

central venous pressure/ right atrium pressure (preload of right ventricle) pressures in pulmonary artery (systolic, dyastolic and mean) PAOP – pulmonary artery occlusion pressure (preload of left ventricle) cardiac output (thermodilution method) SvO2

• Calculated parameters: – – – –

cardiac index, stroke volume pulmonary vascular resistance (afterload of right ventricle) systemic vascular resistance (afterload of left ventricle) oxygen delivery, oxygen consumption, oxygen extraction ratio

– Advantages • allows measurement and calculation of some hemodynamic parameters – shock diagnosis • allows monitoring of treatment response

– Disadvantages: • Risks of central venous catheterization (pneumothorax, cervical or mediastinal hematoma, infection, gas embolism) + specific complications (pulmonary infarction, cardiac perforation, etc.) • requires special equipment (for automatic measurement) • difficult interpretation of hemodynamic data

HEMODYNAMIC EVALUATION OF THE SHOCK STATE METHODS OF CARDIAC OUTPUT EVALUATION AND MONITORING – Thermodilution method • intermittent (Swan-Ganz catheter) • continuous ( modified Swan-Ganz catheter )

– Method of arterial pressure curve analysis (“pulse contour” method ) • PiCCO system (central venous catheter + special arterial catheter + equipment) • LiDCO - Pulse CO system

– echocardiography • transthoracic • transesophageal

INTERMITTENT MEASUREMENT OF CARDIAC OUTPUT - thermodilution method -

HEMODYNAMIC EVALUATION OF THE SHOCK STATE METHODS OF CARDIAC OUTPUT EVALUATION AND MONITORING – Thermodilution method • intermittent (Swan-Ganz catheter) • continuous ( modified Swan-Ganz catheter )

– Method of arterial pressure curve analysis (“pulse contour” method ) • PiCCO system (central venous catheter cateter + special arterial cateter + equipment) • LiDCO-Pulse CO system

– echocardiography • transthoracic • transesophageal

CONTINUOUS MEASUREMENT OF CARDIAC OUTPUT -thermodilution method-

HEMODYNAMIC EVALUATION OF THE SHOCK STATE METHODS OF CARDIAC OUTPUT EVALUATION AND MONITORING – Thermodilution method • intermittent (Swan-Ganz catheter) • continuous ( modified Swan-Ganz catheter )

– Method of arterial pressure curve analysis (“pulse contour” method ) • PiCCO system (central venous catheter cateter + special arterial cateter + equipment) • LiDCO-Pulse CO system

– echocardiography • transthoracic • transesophageal

ECHOCARDIOGRAPHY

HEMODYNAMIC EVALUATION OF THE SHOCK STATE ECHOCARDIOGRAPHY: noninvasive method of hemodynamic monitoring – – – –

estimates the left ventricle telediastolic volume estimates the left ventricle ejection fraction measures cardiac output estimates the abnormalities of myocardial kinetics (areas of hipo - or akinesis) – estimates valvular dynamics – estimates pericardial liquid

HEMODYNAMIC MONITORING OF THE SHOCK STATE OXYGEN SATURATION OF MIXED VENOUS BLOOD (SvO2): • measured in right atrium blood SvO2 • allows measurement of oxygen consumption VO2 • allows measurement of oxygen arterio-venous difference Da-vO2 • allows measurement of oxygen extraction ER O2 • allows monitoring of treatment response

HEMODYNAMIC PARAMETERS IN DIFFERENT TYPES OF SHOCK HR

BP CO

CVP

PAOP SVR

Da-vO2

SvO2

Hypovolemic shock

↑

↓

↓

↓

↓

↑

↑

↓

Cardiogenic shock

↑

↓↓

↓

↑

↑

↑

↑

↓

Septic shock

↑

↓ ↑N

↓N

N

↓

↓

↑

Hemodynamic parameters in different types of shock ABBREVIATION: • • • • • •

HR – heart rate BP – arterial blood pressure CO – cardiac output CVP –central venous pressure PAOP – pulmonary artery occlusion pressure SVR – systemic vascular resistance • Da-v O2 – oxygen arterial-venous difference • SvO2 – mixed venous blood oxygen saturation

MONITORING OF THE PATIENT WITH SHOCK STATE • Respiratory monitoring • Respiratory rate per minute • Respiratory pattern • Pulse oximetry

• Cardiovascular monitoring • Neurological monitoring • State of consciousness

• Temperature monitoring • Measurement of peripheral/core temperature

• Diuresis monitoring • Hourly monitoring of diuresis

• Monitoring of arterial gases • Blood gas analysis

HEMODYNAMIC MONITORING OF PATIENT WITH SHOCK STATE • • • • • •

Blood pressure Heart rate ECG Pulse oximetry Central venous pressure Cardiac output and pulmonary artery occlusion pressure • Oxygen saturation in mixed venous blood • Transthoracic and tranesophageal echocardiography

INITIAL LABORATORY INVESTIGATIONS OF THE PATIENT WITH SHOCK STATE shock → systemic disease→ multisystemic evaluation – – – – – – – – –

blood group and compatibility test plasma and urinary electrolytes plasma and urinary creatinine and urea nitrogen liver function test, amylases haemoglobin, hematocrit, blood white cells count and formula platelets and coagulation tests blood gas analysis ECG chest radiography + others explorations indicated by possible causes

INITIAL TREATMENT OF SHOCK STATES aggressive and early introduction of treatment

correction of tissue perfusion

improvement/correction of organic dysfunction System approach: ABC

INITIAL TREATMENT OF SHOCK STATES • A şi B (airway and breathing): –

clinical evaluation (respiratory rate and respiratory pattern) laboratory investigations (pulse oximetry, blood gas analysis)

Detection of hypoxemia – Oxygenotherapy is rapidly started at first contact with the patient

– Indications of oro-tracheal intubation and ventilatory support : • hypoxemia (↓ PaO2) • ventilatory failure (↓ PaO2 + ↑ PaCO2) • signs of respiratory fatigue : tachypnea >30 respirations/minute abdomino-thoracic balance utilization of accesory respiratory muscles • altered consciousness ( ↓ protection of respiratory airways reflexes) • for the reduction of respiratory muscles oxygen consumption

IOT + ventilatory support+ PEEP → correction of hypoxemia

INITIAL TREATMENT OF SHOCK STATES • C (circulation): Circulatory resuscitation means more than normalization of arterial blood pressure GOALS: • normalization of volemia

volume repletion therapy • normalization of cardiac output inotrope therapy

• normalization of tissue perfusion vasomotor therapy (vasopressor/vasodilatator therapy)

INITIAL TREATMENT OF SHOCK STATES PRACTICAL APPROACH: – – – – – – – – – – –

oxygenotherapy / oro-tracheal intubation and ventilatory support peripheral venous access (în hypovolemia – multiple venous access) blood samples for laboratory analysis ECG monitoring non-invasive arterial blood pressure measurement arterial catheter urinary catheter naso-gastric tube central venous catheter core/peripheral temperature monitoring Swan-Ganz catheter/ echocardiography (if necessary)