Harrisons 270 Approach to the patient with shock

Question 1

Define “shock”

Answer 1

The clinical syndrome that results from inadequate tissue perfusion.

Question 2

Classifications of shock

Answer 2

1) Hypovolemic
2) Traumatic
3) Cardiogenic (Intrinsic & compressive)
4) Septic (Hyperdynamic/early & hypodynamic/late)
5) Neurogenic
6) Hypoadrenal

Question 3

When cardiac output falls, systemic vascular resistance rises to maintain pressure adequate for the heart & brain at the expense of other tissues, such as…

Answer 3

Muscles, skin, and the GI tract

Question 4

3 variables paramount in controlling stroke volume:

Answer 4

1) How much blood is available to squish out of the heart? (Preload)
2) How hard is the body making it to squish that blood out of the heart? (Afterload)
3) How hard can the heart squish? (Myocardial contractility)

Question 5

Pulmonary response to shock:

Answer 5

1) Pulmonary vascular resistance may be relatively greater than systemic resistance, leading to right heart failure!
2) Hypoxemia resulting from underventilated and non-ventilated alveoli
3) Loss of surfactant & lung volume along with increased pulmonary edema decreases lung compliance.

Basically, your lungs don’t like shock AT ALL, and probably we should have a ventilator in our pocket at all times.

Question 6

A major cause of acute lung injury & subsequent ARDS:

Answer 6

Shock, especially resuscitation-induced oxidant radical generation

Question 7

In shock, the body’s inefficient attempt to break down glucose in the absence of adequate oxygen results in what acid, which we commonly measure?

Answer 7

Lactate, or lactic acid!

Question 8

What ratio is a preferable measurement of inadequate tissue perfusion compared to simply measuring lactate?

Answer 8

An elevated pyruvate/lactate ratio reflects inadequate perfusion.

Question 9

Monitoring of shock patients

Answer 9

PUT ‘EM IN THE UNIT!

1) Continuous arterial pressure, pulse, & respiratory rate
2) Foley catheter for UOP
3) Mental status assessed frequently
4) Sedation vacations to assess neuro status & shorten ventilator time

Question 10

When should we consider a Swan-Ganz or a pulmonary artery catheter?

Answer 10

1) Significant ongoing blood loss
2) Fluid shift
3) Underlying cardiac dysfunction

Question 11

What’s the most common form of shock?

Answer 11

Hypovolemic

Question 12

At what level of blood loss do signs of hypovolemic shock appear?

Answer 12

≥ 40%

Question 13

Mild Hypovolemic Shock (< 20% blood loss)

Answer 13

1) Cool extremities
2) Increased capillary refill time
3) Diaphoresis
4) Collapsed veins
5) Anxiety

Question 14

Moderate Hypovolemic Shock (20-40% blood loss)

Answer 14

Same as mild, plus

1) Tachycardia
2) Tachypnea
3) Oliguria
4) Postural changes

Question 15

Severe Hypovolemic Shock ( ≥40% blood loss)

Answer 15

Same as mild + moderate, plus

1) Hemodynamic instability
2) Marked tachycardia
3) Hypotension
4) Mental status deterioration

OBTUNDED IS A REALLY BAD SIGN!

Question 16

Cardiogenic shock & hypovolemic shock have some similarities. What are their differences?

Answer 16

Cardiogenic shock findings include JVD, crackles, & an S3 gallop, while hypovolemic shock does not have these.

Question 17

Why is it so important to distinguish between hypovolemic & cardiogenic shock?

Answer 17

Volume replacement is important for hypovolemic, but additional volume is pretty much the Worst Thing Ever for cardiogenic shock.

Question 18

Initial resuscitation in hypovolemic shock?

Answer 18

TURN UP THE VOLUME!

Rapid infusion of 2-3 L of salt solution (isotonic saline or lactated Ringer’s) over 20-30 minutes.

Question 19

When do we start thinking about blood transfusions in hypovolemic shock? What kind?

Answer 19

Hemoglobin ≤ 10 g/dL

PRBC for hemoglobin, along with FFP for coagulopathy.

Question 20

Inotropic support with vasopressors may be required in hypovolemic shock, but ONLY AFTER what has happened?

Answer 20

Only after volume has been restored!

If you start a peripheral vasoconstrictor before you restore blood volume, you’re gonna have some organ failure on your hands. And your feet. And your GI tract…you get the picture.

Question 21

Once hemorrhage is controlled & the patient is stabilized, what is the new rule for blood transfusions?

Answer 21

Only for hemoglobin < 7 g/dL.

Question 22

Trauma shock is usually hypovolemic, but what are other considerations?

Answer 22

#Inflammatory mediators released from injured tissue
#Continued plasma volume loss into interstitial space
#Direct structural injury to heart, head, or chest: pericardial tamponade, tension pneumothorax, myocardial contusion depressing contractility

Question 23

Compressive cardiogenic shock is…

Answer 23

…caused by compression, which decreases diastolic filling & stroke volume

Question 24

What kind of things might cause cardiogenic shock?

Answer 24

1) Blood or fluid in the pericardial sac causing tamponade

2) Increased intrathoracic pressure: tension pneumothorax, diaphragmatic hernia, excessive positive-pressure ventilation

Question 25

How do we diagnose cardiogenic shock?

Answer 25

1) Clinical findings
2) Chest x-ray
3) Echocardiogram

Question 26

Classic triad of pericardial tamponade

Answer 26

1) Hypotension
2) Neck vein distention
3) Muffled heart sounds

Special bonus: pulsus paradoxus!

Question 27

Clinical findings in tension pneumothorax

Answer 27

1) Decreased breath sounds on affected side
2) Tracheal deviation away from affected side
3) Jugular venous distention

Question 28

How is neurogenic shock is different from cardiogenic?

Answer 28

#Extremities often warm
#Venous dilation in addition to arterial dilation, decreasing venous return & therefore cardiac output
#Requires simultaneous approach to hypovolemia & vasomotor tone

In short: bust out that norepinephrine!

Question 29

What are our favorite sympathomimetics for shock?

Answer 29

1) Dobutamine
2) Dopamine
3) Norepinephrine