Hemodynamics

Question 1

If you get systolic pressure variation (with A-line) >10 mmHg with positive pressure ventilation- what does this indicate?

Answer 1

It is an indirect measurement of volume status– consistent with hypovolemia

Question 2

Femoral artery A-line placement

Answer 2

Palpate femoral artery (VAN- V closest to P), puncture site below inguinal ligament

Question 3

Relative contraindications to A-line placement

Answer 3

Infection at site, ischemia, raynaud’s, traumatic injury, AV fistula in same extremity, lymphadenectomy, no collateral flow

Question 4

Radial artery A-line placement positioning

Answer 4

Palm up on flat surface, dorsiflex wrist 30-45 degrees supported with towel (avoid hyper dorsiflexion), tape hand to work surface

Question 5

What are hemodynamics influenced by?

Answer 5

blood pressure, blood flow, characteristics of blood- poiseuille’s law- (change in pressure * r^4 * pi/ viscosity of blood * vessel length * 8)

Question 6

Systolic pressure

Answer 6

Max pressure- exerted when heart beats, reflects volume & speed of ejection & compliance of the aorta

Question 7

Diastolic Pressure

Answer 7

Minimum pressure- exerted in between heart beats, reflects vascular resistance & competence of the aortic valve

Question 8

Mean Arterial Pressure

Answer 8

Best indicator of tissue perfusion! Average driving pressure of blood during the cardiac cycle.. can use to calculate CPP (Map-ICP)

Question 9

Pulse Pressure

Answer 9

Systolic - Diastolic, reflects difference in volume ejected from LV into arterial vessels & volume that is already there– function of SV & SVR.. wide PP – increased SV, decreased SVR like in sepsis, narrow PP– decreased SV & increased SVR like in tamponade

Question 10

Korotkoff sounds

Answer 10

Turbulent blood flow will occur when cuff pressure is greater than diastolic & less than systolic (tapping sounds)

Question 11

How does an automatic blood pressure monitor work?

Answer 11

Measures MAP (point of max oscillation amplitude) & calculates systolic & diastolic from formulas that examine the rate of change of pressure pulsations– diastolic most unreliable

Question 12

Blood pressure cuff sizing

Answer 12

Compare length of bladder inside the cuff with the circumference of the patients arm- bladder at least 80% reading should be accurate

Question 13

Shape of A-line waveform depends on?

Answer 13

Force generated by ventricle, speed of ejection, compliance of arterial vessels, rate of forward blood runoff (SVR)

Question 14

Oscillations after fast flush of A-line

Answer 14

2 oscillations occur after fast flush- should be no more than 1/3rd of previous oscillation.. just one flush- have overdampening, “ringing” or repeated- underdampening

Question 15

A-line complications

Answer 15

Ischemia, pseudoaneurysm, hemorrhage, hematoma, embolism, local infection, sepsis, neuropathy, misinterpretation of data

Question 16

Effect of patient positioning on NIBP

Answer 16

NIBP will be higher in the dependent arm (if patient on side- the lower arm) and lower in the nondependent arm

Question 17

CVP monitoring- indications, normal

Answer 17

Indication of preload of RV: low with tachycardia and hypotension usually is hypovolemic, high with hypotension indicative of myocardial congestion (MI, tamponade, tension pneumo).. normal is 6-10 mmHg

Question 18

Prior to insertion of PA catheter what needs to be done?

Answer 18

Flush all lumens, check integrity of balloon with PASSIVE deflation, prepare transducer, connect lines to appropriate lumens (PA distal, CVP proximal)

Question 19

PA catheter insertion

Answer 19

Insert to depth of 20 cm, CVP waveform identified, inflate balloon to carry through RA, RV & into PA)

Question 20

Normal PA pressures

Answer 20

Systolic: 15-30/ Diastolic: 5-15 (mmHg)

Question 21

Normal PACWP

Answer 21

4-14 mmHg

Question 22

Complications of CVP & PA lines

Answer 22

Infection, pneumo, vessel erosion/perforation, venous air embolism, hemorrhage, rupture of PA, dysrhythmias

Question 23

LiDCO

Answer 23

Lithium dilution cardiac output, minimally invasive way of monitoring continuous CO

Question 24

What does EKG monitor

Answer 24

Electrical impulses (HR, arrhythmias, ischemia, pacemaker function, electrolytes) NOT contractility/output – think of PEA

Question 25

How does EKG monitoring work

Answer 25

Silver chloride electrodes have conductive gel which decreases electrical resistance of skin, small signal amplified and broadcasted

Question 26

Lead II function

Answer 26

Rhythm detection- inferior portion of heart (RCA)

Question 27

Lead V5 function

Answer 27

Left ventricle (LAD)- placed 5th intercostal space anterior axillary line

Question 28

Lead I function

Answer 28

Circumflex artery monitoring

Question 29

Respiratory impedance monitoring

Answer 29

Measures movement of chest by electrodes- not fool proof

Question 30

Pulse oximetry monitoring

Answer 30

Measurement of arterial hemoglobin oxygenation- measures pulsatile signals across perfused tissue at 2 discrete wavelengths (absorbance of light indicates state of hemoglobin)

Question 31

What are the 2 light emitting diodes in pulse oximetry

Answer 31

Infrared (940 nm wavelength-oxyhemoglobin) Red (660 nm wavelength - reduced hemoglobin)

Question 32

Carboxyhemoglobin appearance

Answer 32

Just like oxyhemoglobin- false high

Question 33

Methemoglobin appearance

Answer 33

Gives saturation of 85% regardless of true oxygenation