Critical Care 1

Question 1

Arterial blood pressure is the product of _________ and ________

Answer 1

Cardiac output and resistance to flow

Question 2

Cardiac output consists of _______ and _______

Answer 2

Stroke volume and heart rate

Question 3

Stroke volume is determined by ______, _______, and _______

Answer 3

Preload, afterload, and contractility

Question 4

MAP = [ _____ + (2 x _____)]/3

Answer 4

SBP ; DBP

Question 5

Normal MAP is?

Answer 5

70 to 100 mmHg

Question 6

MAP required for adequate cerebral perfusion?

Answer 6

60 mmHg

Question 7

What is preload?

Answer 7

Preload can be defined as ventricular end diastolic volume.

Question 8

Signs of hypoperfusion?

Answer 8

Cold extremities, AMS, decrease in urine output

Question 9

Why is lactic acid formed during hypoperfusion?

Answer 9

During periods of hypoperfusion, tissue receives less oxygen, and in turn uses anaerobic metabolism. Lactic acid is a byproduct of anaerobic metabolism.

Question 10

Normal SBP

Answer 10

90 - 140 mmHg

Question 11

Normal DBP

Answer 11

60 - 90 mmHg

Question 12

Normal Heart Rate

Answer 12

60 to 80 beats per minute

Question 13

Normal lactic acid levels

Answer 13

< 1 mmol/L

Question 14

Normal central venous oxygen saturation (ScvO2)

Answer 14

70% to 75%

Normal oxygen extraction from the blood is about 25% to 30%

Question 15

How do you determine cardiac output?

Answer 15

Heart Rate x Stroke Volume

Question 16

What is normal cardiac output?

Answer 16

4 to 7 L/minute

Question 17

How would you determine a patient’s Cardiac Index?

Answer 17

Cardiac Index is:

Cardiac output / BSA

Question 18

The four types of shock

Answer 18

1) Distributive or vasodilator
2) Hypovolemic
3) Obstructive (tamponade or PE)
4) Cardiogenic (heart failure)

Question 19

Indicators of distributive or vasodilatory shock

Answer 19

High cardiac Index early, but shifts to low.

Low central venous pressure (or PCWP) early but then increases to normal or high

Low SVR (systemic vascular resistance)

Patients with distributive shock are generally hyper dynamic (high CI) with vasodilation (low SVR) and increased vascular permeability (“leaky capillaries”), which causes fluid to shift into the interstitial spaces.

Question 20

Cardiac indicators of hypovolemic shock

Answer 20

Low cardiac Index

Low CVP/PCWP

High SVR (to maintain perfusion)

Question 21

Cardiac indicators of obstructive shock

Answer 21

Low cardiac Index

Low CVP/PCWP if impaired ejection, or high is it is impaired filling (for example tamponade)

High SVR

Question 22

Cardiac indicators of cardiogenic shock

Answer 22

Low cardiac Index

High CVP/PCWP

High SVR

Patients with cardiogenic shock have acute heart failure, which causes reflex vasoconstriction secondary to reduced tissue perfusion. This increases blood flow to vital organs but worsens heart function due to increased afterload and decreased excretion of Na+ and water.

Question 23

Treatment of hypovolemic shock

Answer 23

Basics of treatment include restoring intravascular volume and oxygen carrying capacity (I.e. Volume resuscitation with crystalloids or colloids or using blood products if indicated).

Packed red blood cells can be used if hemoglobin is < 7 g/dL or if they are actively bleeding.

Question 24

Vasopressor use in hypovolemic shock

Answer 24

Which vasopressors can be helpful, the first concern is volume resuscitation. In fact the adverse effects of vasopressors (I.e. Arrhythmias and ischemia) are greater if patients have not received adequate fluid resuscitation.

I would guess because the doses required to achieve adequate results would be higher due to the continuation of the hypovolemic state.

Question 25

Treatment of obstructive shock

Answer 25

First and foremost, treatment of the actual obstruction is #1. Fluids and vasopressors can help, but won’t necessarily improve outcomes.

Question 26

What four measures should be completed within 3 hours of a patient presenting with sepsis or septic shock?

Answer 26

1) Measure lactate level
2) Obtain blood cultures prior to administering antibiotics
3) administer broad spectrum antibiotics
4) administer 30 mL/kg crystalloid for hypotension or lactate 4 mmol/L or greater

A side note: when administering large volumes of crystalloids, it’s better to use solutions closer to extracellular fluid, such as LR or plasmalyte. Chloride rich solutions such as NS or 5% albumin can lead to AKI and metabolic acidosis

Question 27

What measure should be completed within 6 hours of a patient presenting with sepsis or septic shock with persistent hypotension unresolved with fluids?

Answer 27

Administration of vasopressors to maintain a MAP of 65 mmHg or greater.

Norepinephrine is the initial vasopressor of choice

Generally, vasopressor hierarchy would go:

• Norepinephrine
• Vasopressin (1.8 units/hour)
• Epinephrine
• Dopamine could be used at any time as well, but does have a higher risk of arrhythmias.
• Phenylephrine can also be used at any time, and is preferred in patients with a high risk of cardiogenic side effects due to its reduced risk of arrhythmias and hypotension.

Question 28

Vasopressor administration (line preference and extravasation management)

Answer 28

Central line preferred due to decreased risk of extravasation and subsequent ischemia.

• If extravasation does occur, phentolamine (a-receptor antagonist) can be used to reduce tissue necrosis.
• Other extravasation management options include nitroglycerin 2% ointment applied q6 hours to the area around the site, or terbutaline subQ to the site

Question 29

Norepinephrine

Answer 29

• Dose: 0.05 - 1 mcg/kg/min (Legacy dosing)
• Receptor affinity: highest for alpha-1 and beta-1, with no beta-2 or dopamine activity.
• Decreases renal perfusion, increases SVR and BP.
• Can induce tachyarrhythmias and myocardial ischemia.