Basic Overview of Hemodynamics

8/12/2019 Basic Overview of Hemodynamics

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Hemodynamics and Shock

NUCO 4220

Spring 2014

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Tissue and Organ Perfusion Influenced by

Amount of O2 in arteries that reaches cell(how much pumped from heart reaches

cells)

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Factors that Influence MAP

- Heart- Size of vascular bed

- Volume of blood w/in vessels


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MAP (Mean Arterial Pressure)

Mean arterial pressure

SVR x CO (+CVP: often negligible)

OR [(2Xdiastolic) + systolic] / 3 (never calculate)

Norm: 70-110 mmHg

- avg BP (more direct measure than cuff)

- Arterial pressure when heart pumping

- An indicator of perfusion

- MAP > 60 to perfuse kidneys, brain and

coronary arteries (gut takes hit early)

- MAP 101 = good perfusion3


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Arterial Line

2 uses: get blood, getMAP

Change tube q96h

Sterile dressings last

about a wk

*Dont memorize waveform*

jeffreymlevinemd.com 4


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Arterial Line Set Up

aic.cuhk.edu.hk 5

500ml Norm Saline

(not always w/

heparin, risk for HIT)

Pressure Bag to

force fluid against

artery (which pushes

stuff out)

All sit in transducer

holder, leveled at

right atrium


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Transducer placement

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Plastic holder often onHOB bc always has to be

zeroed to give accurate

read

0 it every shift so dont getatmospheric pressure

Phlebostatic Axis:

4thintercostal space and

mid-axillary (btw interior-

posterior diameter) @

right atrium


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CVP or RA Pressure

MAP = central core BP

CVP/RA = central venouspressure (comes from RA)

Long line inserted subclavian

(jugular/femoral risk infxn)

Tip in RAgives sense of fluid

thats been returned to heart

from body

Ex: low UO, so measure howmuch of bolus circulating well

How much blood to pulmonary

arteries to get oxygenated

Norm: 2-8 7


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CVP

Norm 2-8 mm Hg

Guidelines:

8-12 to avoid hypovolemia

(ex: burn)

>12 if pt on mechanical vent

PEEP volutrauma can

compress capillaries and decr

vol to heart (and CO)

giveextra vol so vessels less likely

to collapse

Level to RA and 0 every shift

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Swan Ganz Catheter

nlm.nih.gov 9

RA to RV up into pulm vasculature Risk perforate lung, valve, artery, infxn,

dysrhythmias (block), etc.


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Swan Ganz Catheter

10

Most have 6 ports

Can deliver inotrope

into heart immediately

Can get CVP Only way to continuouslymonitor pulm artery

pressure


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Swan-Ganz Measurements (mmHg)

R Atrium (CVP) Right Ventricle

Systolic 15-30

Diastolic 3-8 Pulmonary Artery

How constricted or dilated is pulm pressure

Pulmonary Wedge (L. Atrium)Indirect 2-15

Wedge off pressure for a moment and get

reflective value of LA (based on build-up in RA?)11


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Pulmonary Artery Pressure

Systolic 15-25

Diastolic 8-15

Mean 10-20

Pulm HTN = PAP > 25

Is pulm system vasoconstricted?

Ex: improve CO by giving fluid, but if still low, getPAP:

High PAP (constricted), fluid cant get throughresistance w/ same vol & speed to produce CO on otherside (tx: vasodilate)

CVP can look good but still low perfusion, giving lots offluids risks pushing into RHF

Also obtained from cardiac cath

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Pulmonary Artery Pressure

Heart Failure

Sepsis

Clot Low flow not necessarily r/t constriction

Clot in pulm vasculature would cause low flow

Effectiveness of Tx/ Meds

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Mixed Venous Oxygen

% of reduced hgb left after tissue oxygen extraction

How much O2 left on hgb after it blood has circulated

Blood gets O2 in pulm vasculature, pumps to body,

and has lowest O2 right before entering again

SvO2 Normvalue 60 - 80%.

< 60 if cells/organs need more

Ex: in marathon, cells need more O2, so pull free O2 frombody, and wont see immediate drop in SaO2 and SvO2??

but septic pt wont have that O2 reserve and see quick

drop in SaO2

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Oxygen Delivery

Hgb

O2 saturation

CO

http://www.bing.com/images/search?q=oxygen+delivery+cells&FORM=BIFD#focal=88d8a54e16da437f9dc6864efb8e19f2&furl=http%3A%2F%2Fwww.oneminutecure.com%2FDissociationHemoglobinOxygen.jpg 15
http://www.bing.com/images/search?q=oxygen+delivery+cells&FORM=BIFDhttp://www.bing.com/images/search?q=oxygen+delivery+cells&FORM=BIFDhttp://www.bing.com/images/search?q=oxygen+delivery+cells&FORM=BIFDhttp://www.bing.com/images/search?q=oxygen+delivery+cells&FORM=BIFD


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CO = Heart Rate x Stroke Volume

Heart Rate Stroke Volume (SV)

Fluid from LV left over after

final LV contraction

Amount of vol of blood being

pumped to tissues

Norm CO = 4-8L/min

End-Diastolic Vol minusEnd-Systolic Vol

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Stroke Volume

Measurement of Volusing Echocardiogram How much making it out to tissues

Gives info of how circulating, how well its squeezingon inotrope (can actually see contraction/squeeze),see color-coded arterial & venous flow

Used to assess vol response to fluids and meds

Esophageal Doppler***** Probe into esophagus near heart gives good output

Non-invasive Doppler: THE FUTURE

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Shock- Side-effect (syndrome/condition) r/t how much vol

circulating to perfuse organs

- Decr blood vol w/o constricted capillary bed can lead toshock- Ex: hemorrhage (losing vol), so if capillary bed doesnt constrict

and MAP doesnt incr, organs will die quickly

- Capillary beds dilate excessively, go into shock bc not enoughtension/resistance to perfuse organs

- Compensate early one (ie capillaries constrict when vol decr),but if doesnt, go into shock fast

It is a widespread abnormal cellular metabolism that occurswhen the human need for oxygenation and tissue perfusion

is not met to the level needed to maintain cell function.All body organs are affected and either work harder to

compensate or fail due to hypoxia

Iggy, Chapter 39, pp 826


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Blood Volume, Capillary Bed & MAP

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Hypoperfusion

Cellular hypoxia (w/ build-up of lactic acid) Cell death r/t hypoxia cause incr lactic

Aerobic (with O2) metabolismanaerobic

(without O2) metabolism

lactate and H+ions

lactic acidosis (metabolic)

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Lactate

0.51 mmol/L: Normal

2 mmol/L: Slight elevation

25 mmol/L: Mild-moderate

> 5 mmol/L: Lactic acidosis (with low pH)

**Concern when above 2

Get ABG w/ lactatetells to what degreebody didnt or no longer able tocompensating

Lactic acid means no compensationneed to

intervene 21


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Hypoxia Tolerance

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Heart, Brain, Kidney canttoleratehypoxemia

Skin, Skeletal Muscles can tolerate

hypoxia for awhile

Liver = middle rode tolerance


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4 Types of Shock

Hypovolemic (low vol) Give fluids

Cardiogenic

Ex: MI impairs CO

Distributive (anything that affects periph vasc) Septic

Anaphylactic Neurogenic

Obstructive (rare)23


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Stages of shock (Iggy, Table 39-3) Early (preshock)

MAP decr by 5-10 HR up a little to incr CO and compensate

Some vasoconstriction

Compensatory (**identify & intervene**)

MAP decr 10-15 HR up (whats pt baseline), decr UO

Ned to reverse quickly before tissue death

Progressive Compensatory mechanisms fail

MAP decr 20-40 , severe hypoxemia, poor CO & UO

Refractory Almost impossible to reverse

MODS24

H l i Sh k


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Hypovolemic Shock

Fluid Depletion

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Extreme dehydration: Dehydration = vol loss (expect incr CO (w/ incr HR & BP)

and capillary constriction

When cant compensate, MAP decr

Blood loss:

Losing O2 carrying capacity

Cant compensate long

Tx:

Pressure bag fluids

Central line (access and CVP read)

If hemorrhage: start fluids before blood arrives (even if not

type & screen yet)

C di i Sh k


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Cardiogenic Shock

Direct Pump Failure

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So much cardiac damage that pump doesnt work

Low CO, so capillaries need to vasoconstrictor to

maintain circulating vol

Dont give extra vol bc dont have mechanism tohelp w/ CO

Dont give inotrope, bc it make heart squeeze too

much and further cardiac cell death

Tx: cath lab and/or LVAD type pumps until

transplant (if needed)

IABC: Intra aortic counterpulsation


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IABC: Intra-aortic counterpulsation

(Intraaortic balloon pumpIABP)

Cardiac cycle

Increase coronary

perfusion

Decrease afterload

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http://library.med.utah.edu/kw/pharm/hyper_heart1.htmlhttp://library.med.utah.edu/kw/pharm/hyper_heart1.html


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Distributive Shock:

Massive Vasodilation

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Leaking vessels

Spinal cord injury:

Nerve innervation

affects constriction,cant hold tone

Losing fluid to tissues


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Distributive Shock

Septic Anaphylactic

Epi-pen is vasoconstrictor

Neurogenic

Too many opioids or drugs affecting tone(?)

Tx:

Lots of vasodilation: incr vol (to fill space) orincr CO (to incr pressure)

Potentially get inotrope

Correct underlying condition

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Sepsis Bundles:


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Sepsis Bundles:Surviving Sepsis Campaign (2008)

Element 1: Measure serum lactate (act if >2)

Element 2: Get blood cultures prior to giving broad-spectrum

antibx

Element 3: Administer antibx w/in 3hrs of ED & 1hr of Non-EDadmit

Element 4: Tx hypotension and lactate w/ fluids. Maintain MAP>

65. Use vasopressors for ongoing hypotension.

- Give liters of fluids, once MAP >65, stop boluses, but continuefluids

Element 5: Maintain CVP > 8mmHg and Mixed Venous O2 > 65%

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Sepsis Management BundleEvidence-based goal is to perform all indicated tasks 100% of time w/in first

24 hrs of presentation

1. Administer low dose steroids

r/t inflammatory mediators

2. Maintain glucose control lower limit of norm but


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Assessment CV status1stsign of

shock As MAP drops, pulse

pressure low (lesspalpable)

Renal Decr UO

Respiratory

Incr RR

Metab acidosis so respkicks in to compensate(blow off CO2)

Integumentary

Cool skin, diaphoresis,slow cap refill, 32

Musculoskeletal Tolerates hypoxia well, so

see late changes Decr movement and

strength

CNSalso an early sign

Something off Incr neuron firing: twitch,agitated, anxious

Lab valuesH/H, Lacticacid, K+

Get ABGs after other tasks Adjust K+ quickly (if

hyperkalemia, glucose orCa+ (?) to send K+intracellularly, can give

kaexolate later)


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Management

Oxygen therapyneed O2

IV therapyCrystalloids, Colloids, Blood

Hemodynamic monitoringMAP,CVP, (SV) Drug therapyVasoconstrictors, Inotropes,

Myocardial perfusion agents

Treat underlying condition If anaphylaxis, give epi; if MI, etc.

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PracticeWhich client should the nurse evaluate for

neural-induced distributive shock? A. The 25-year-old receiving 500 mg of

penicillin IV.

B. The 47-year-old with sudden-onsetsevere chest pain and dyspnea.

C. The 21-year-old who has received 4

mg of morphine IV for acute pain. D. The 82-year-old who has had severevomiting and diarrhea for 2 days.

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Case Study

A 53-yr old man is s/p open reduction of right

forearm after falling from a tree while trimmingit. PMH: mild hypertension, 15 # underweight.PSH: smokes two packs of cigarettes anddrinks a six-pack of beer daily. VS : BP,142/90; HR 86; RR 18; O2 Sat 97%. Exam:forearm dressing is dry & intact, fingers arewarm & pink with good cap refill. He responds

to his name, but does not open his eyes.1. Are any indications of shock currently

present?

It is now 15 minutes later BP 140/92; HR 92;


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It is now 15 minutes later, BP 140/92; HR 92;

RR 18, O2 Sat 95%. Dressing is dry & intact,

fingers are slightly cool, and cap refill is slightly

slower than baseline assessment. He is awakeand tells you that his right arm hurts and that

he is thirsty. You administer the prescribed

analgesic by injection.

2. Are any indications of shock currently

present? .3. What should you check regarding the

coolness of the fingers?

4. Should you give him sips of water?

15 minutes later VS are BP 132/96; HR 100;


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15 minutes later, VS are BP 132/96; HR 100;RR 22. Pain is better but he is very thirsty,light-headed & mildly nauseous. He reports

belcheing. Postop orders state: Remove IVafter 1000 mL has infused, if stable

5. Are any of the changes in VS a cause forconcern?

6. Could the changes in VS be related to eitherhis pain or the analgesic?

7. Where should you look for postop bleeding?

8. Should you remove his IV at this time?

9. Should retake VS in 15 minutes?


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10 minutes later: BP, 106/80; HR 112; RR 26,

O2 Sat 90%. You start to check his cap refill,

he says Josey (his wifes name), bring me abucket, I feel sick. He vomits a large amount

of bright red blood.

10. What vital sign changes are consistent with

shock?

11. What stage of shock is present?

12. What is the most likely cause of thebleeding?

13. Is there anything the nurse could have

d diff tl t id tif h k li ?

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Basic Overview of Hemodynamics