Approach to a case of hypotension and shock

Approach to a case of Hypotension and Shock

Introductory Lecture Series

Department of Medicine

Dr C Khati

Shock is an Emergency

Assessment and resuscitation go hand in hand because time is critical

Learning Objectives

• To learn definition and meanings of related terms

• To be able to list the steps in pathogenesis of shock

• To be able to list the 3 major categories of shock, and 3 others

• To be able to enumerate common causes of shock in each of the 3 major categories

Learning Objectives

• To comprehend that more than one mechanisms may operate in a given patient

• To list steps in rapid initial assessment

• To enumerate broad steps in resuscitation of shock

Definitions and Meanings

• Stroke Volume (SV): Amount of blood pumped out with each systole. Pulse pressure correlates well with SV

• Heart Rate (HR): Number of ventricular contractions per minute

• Cardiac Output(CO): Amount of blood pumped out in each minute.

CO = SV X HR





CO = SV X HR





CO = SV X HR





CO = SV X HR


Systolic Blood Pressure (SBP)

Diastolic Blood Pressure (DBP)


Pulse Pressure (PP): SBP – DBP correlates well with Stroke Volume .

Mean Arterial Pressure (MAP): DBP + 1/3 PP

Definition and Meanings

• Hypotension is diagnosed if blood pressure falls below 90/50 mmHg in adults.

• Hypotension may also be diagnosed if an individual has a sudden drop in SBP of 30 - 40 mmHg or more from their baseline, or

• An orthostatic (postural) drop in DBP of 15 mm Hg









Remember

Hypotension is a late manifestation of shock


• The Jugular Venous Pressure (JVP) is an observed pressure over the jugular veins

• The Central Venous Pressure (CVP) is a measured pressure in the right atrium by means of a catheter attached to a manometer








Capillary Nail Refill Test• Pressure is applied to the nail bed until it turns white

(blanching). Then pressure is removed.• Time taken for return of pink colour to the nail is

considered (capillary refill).

• Blanch time > 2 seconds is a delayed response.–Dehydration– Shock– Peripheral vascular disease (PVD)– Hypothermia


Capillary Nail Refill Test• Pressure is applied to the nail bed until it turns

white (blanching). Then pressure is removed.• Time taken for return of pink colour to the nail is

considered (capillary refill).• Blanch time > 2 seconds is a delayed response.

–Dehydration– Shock–Peripheral vascular disease (PVD)–Hypothermia

Definitions and MeaningsShock or circulatory failure is the clinical syndrome that

results from generalized inadequate tissue perfusion lasting for some time. Where oxygen delivery fails to meet metabolic requirements of the tissues.

It is defined by the presence of multisystem, end organ hypo perfusion causing cellular injury.

Cellular injury further compromises perfusion through functional and structural changes in the microvasculature through mediators

Thus, setting up a vicious cycle.











Hypoperfusion

Demand supply

mismatch

Cellular Dysfunction

Release of mediators

Structural and functional changes in

microvasculature

Hypoperfusion

Demand supply

mismatch




microvasculature

Hypoperfusion

Demand supply

mismatch




microvasculature

Hypoperfusion

Demand supply

mismatch




microvasculature


• Early Shock

• No significant organ failure

• Late Shock

• Multi-organ failure. > 80% mortality


• Early Shock


• Late Shock



• Early Shock


• Late Shock



• Systemic Vascular Resistance (SVR): An index of arteriolar constriction throughout the body

• Calculated by dividing the blood pressure by the cardiac output. MAP/ CO = SVR

• Pulmonary Vascular Resistance (PVR): An index of arteriolar constriction in the pulmonary circulation













Pathogenesis of Shock

MAP = CO X SVR


MAP = CO X SVR

or

MAP/ CO = SVR


MAP= CO X SVRMAP- Mean Arterial Pressure (Measurable:DBP +1/3 PP)


MAP= CO X SVRMAP- Mean Arterial Pressure -Measurable (DBP + 1/3 PP)

CO- Cardiac Output -Inferable (Pulse Pressure =SBP- DBP)


MAP= CO X SVRMAP- Mean Arterial Pressure (Measurable: SBP + DBP/ 2)

CO- Cardiac Output (Inferable; Pulse Pressure= SBP- DBP)

SVR-Systemic Vascular Resistance: (can be calculated)


• Diminished Cardiac Output

Is the Heart full or empty?



• Heart Full (Cardiogenic)

• Heart Empty (Hypovolemic)



• Heart Full (Cardiogenic)

• Heart Empty (Hypovolemic)

• Increased Cardiac Output


Diminished Cardiac Output

MAP/ CO = SVR

• Narrow Pulse Pressure (PP correlates well with SV)

• Low volume pulse

• Cool extremities

• Delayed capillary refill


Increased Cardiac Output

MAP/ CO = SVR

• Wide Pulse Pressure (esp. low DBP)

• Bounding pulse

• Warm extremities

• Rapid capillary refill

Pathogenesis of Shock ( CO)

MAP = CO X SVR

or

MAP/ CO = SVR

• If an hypotensive patient has high CO, it can be inferred that reduced BP is a result of decreased SVR


MAP = CO X SVR

or

MAP/ CO = SVR

• If a hypotensive patient has high CO, it can be inferred that reduced BP is a result of decreased SVR


• Low Intravascular and Cardiac Volume

• Increased Intravascular and Cardiac Volume

Is the Heart full or empty?


Low Intravascular and Cardiac Volume

• Hemorrhage

• Volume Losses (vomiting, diarrhea, Polyuria)

• JVP/ CVP is reduced

• What do you think the other findings will be?


Low Intravascular and Cardiac Volume

• Hemorrhage

• Volume Losses (vomiting, diarrhea, Polyuria)

• JVP/ CVP is reduced

• What do you think the other findings will be?

Pathogenesis of Shock( CO)

Increased Intravascular and Cardiac Volume

• Increased JVP/ CVP

• Extremity edema

• S3/ S4 gallops

• Basal crepitations

• X Ray – Cardiomegaly

– Widened vascular pedicles, Kerley B Lines

– Pulmonary edema

Common Categories of Shock

1. Cardiogenic

2. Hypovolemic

3. High CO with decreased SVR (Warm Shock)

4. Neurogenic- Major brain or spinal injury-

5. Hypoadrenal- Refractory Shock

6. Obstructive- Tamponade, Pulmonary Embolism, Tension Pneumothorax

Common Categories of Shock

1. Cardiogenic

2. Hypovolemic

3. High CO with decreased SVR (Warm Shock)

4. Neurogenic- Major brain or spinal injury-

5. Hypoadrenal- Refractory Shock

6. Obstructive- Tamponade, Pulmonary Embolism, Tension Pneumothorax

Basic Changes in Each Category

Cardiogenic Hypovolemic High CO with decreased SVR

CO Low Low High



CO Low Low High

SVR High High Low/ High (late)



CO Low Low High


MAP Low Low Normal/ Low



CO Low Low High



CVP High Low Low/ High (late)



CO Low Low High



CVP High Low Low/ High (late)

Venous Oxygen saturation

Low Low High

Common Causes of ShockCardiogenic Hypovolemic High CO with

decreased SVR

MI GI Losses SIRS

Arrhythmias Heat stroke Sepsis

Myocarditis Hemorrhage Pancreatitis

Anaphylaxis

Tamponade Trauma Thyrotoxicosis (storm)

Injuries Burns Burns

AV Shunts

Liver Failure

Steps in rapid initial assessment

• Confirm shock and assess severity

• Assess category of shock

• Low CO or high CO

(Heart empty or full)

• Start resuscitation simultaneously













Goal of Resuscitation ?

• Re establish adequate tissue perfusion to prevent or minimize end- organ injury

Goal of Resuscitation

• Re establish adequate tissue perfusion to prevent or minimize end- organ injury

Resuscitation is different in each category


Treatment for Ischemia

IV Fluids Antibiotics

Ionotropes Colloids EGDT*

After load reduction

Low dose steroids

Activated Protein C


• Patient and clinical situation assessment• Vitals and quick examination to assess category

of shock-• Core temperature• Cold or warm peripheries• Pulse- bounding or low volume• Capillary filling- slow/ rapid• Raised JVP, S3 and basal crepts in cardiogenic• Respiration• Urine Output


• Patient and clinical situation assessment• Vitals and quick examination to assess

category of shock-

–Core temperature

–Cold or warm peripheries

–Pulse- bounding or low volume

–Capillary filling- slow/ rapid

–Raised JVP, S3 and basal crepts in cardiogenic

–Respiration

–Urine Output

Terms in Assessment/ Treatment

• APACHE II Score- Acute Physiology and Chronic Health Evaluation II (with points for age and co-morbidity)

• Glasgow Coma Score

• ACLS- Advanced Cardiac Life Support

• Old acronym- ABC (still valid)

General Features of Shock

• Hypotension (SBP < 100)

• Tachycardia (>100)

• Cold clammy skin (Low CO)

• Rapid shallow respiration

• Drowsiness, confusion and irritability

• Oliguria (<30ml/hr)

• Elevated / reduced CVP

• Multi- organ failure

Steps in Resuscitation

• Airway and Respiration

• Circulation

• Early Goal Directed Therapy (EGDT)

• Multisystem organ support

32 year old young lady, on NSAIDS

• Dyspepsia X 5 days

• Dark tarry stools X 2 days

• Profound weakness X 2 days

• Syncope this morning

• Cold clammy and sweating, Poor capp refill

• BP 70/50 mm Hg lying; 60/ 35 mm standing

• Pulse 140/ min, thready

• Resp- 36/ min

• Pallor

40 year busy doctor, HT

• Chest Pain X 1 Hour

• Sweating, palpitations and breathlessness

• Restless, sweating, cold and clammy

• BP 100/76 mm, Pulse 110/ min, low volume

• Resp- 26/ min, prefers to be propped up

• Poor capillary refill

• JVP/ CVP raised

45 year old diabetic male

• Fever, cough and rusty sputum X 2 days

• Weakness X 1 day

• No urine X12 hours

• Temp- 40 degrees C, warm extremities

• Pulse 120/ min, good volume

• BP 108/30 mm, Resp rate 40/ min

• Cyanosis +, JVP not raised

• Capp refill good

Take Home Messages

• Shock is an Emergency. Assessment and resuscitation go hand in hand because time is critical

• Hypotension is a late feature of shock. Do not wait for hypotension before starting treatment

• Clinical setting and simple examination of MAP, pulse pressure, heart rate, JVP and nail cappillarybed refill can give vital clues. Tachypnea and sweating should also make you alert.

Take Home Messages

• Urine output is a good indicator of renal (tissue) perfusion

• Goal of resucitatation is to re establish adequate tissue perfusion to prevent or minimize end-organ injury

Health & Medicine

Approach to a case of hypotension and shock