Graphics

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Mechanical Ventilation

Ventilator Graphics

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Graphic Waveforms• Scalar graphics

• pressure vs. time• flow vs. time• volume vs. time

• Loop graphics• flow vs. volume• pressure vs. volume

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Graphic Waveform Use• Monitor ventilator function• Improve patient/ventilator interaction• Identify autoPEEP• Calculate respiratory mechanics

Graphics

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Remember! (VC)• vol delivered depends on flow, TI• vol delivery is same each breath• flow waveform is same each breath• flow waveform does not change with

changing CL, RAW• pressure produced varies with CL, RAW,

type of flow waveform

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Pressure vs. Time

F = EEPC = start of pauseX + y = TI

E = early exp pressB = PIPy = pause

D = PplatA = start of inspx = TI

VCSIMV (VC)

z = TE

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F = EEPC = early insp press

E = early exp pressB = PIPz = TE

D = PplatA = start of inspx = TI

Pressure vs. TimePC

SIMV (PC)

Graphics

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Pressure vs. Time

P

tI

E

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Pressure vs. Time

P

t

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Pressure vs. Time

P

t

Graphics

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Pressure vs. Time

P

t

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Pressure vs. Time

P

t

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Pressure vs. Time

P

t

Graphics

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Pressure vs. Time

“Flow Starvation”

RX -

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Pressure vs. Time• Also examine negative pressure

deflection:

• too deep• lasts too long

⇒ ↑ WOB

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Pressure vs. Time

P

t

Graphics

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Pressure vs. Time• Summary - Use PT graphics to:

• ID breath type• adjust flow rate• assess work to trigger breath• detect autoPEEP• assess plateau & calculate CS

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I = PEFRX + y = TI

K = end exp flowH = zero flow phasey = pause

J = decelerating exp flowG = PIFRx = TI

Flow vs. TimeVC

SIMV (VC)

z = TE

18I = PEFR

K = end exp flowH = decel insp flowz = TE

J = decelerating exp flowG = PIFRx = TI

Flow vs. TimePC

SIMV (PC)

Graphics

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Flow vs. Time

• rectangular = square• descending = decelerating• ascending = accelerating• sinusoidal = sine

Flow WaveType

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Flow vs. TimeFlow

t

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EXTREMELY IMPORTANT!!

AutoPEEP = air-trapping = hyperinflation⇓

↑ risk of barotrauma↑ mean airway pressure

hemodynamic compromise

Graphics

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Flow vs. Time• Summary - Use FT graphics to:

• ID breath type• ID waveform type• detect autoPEEP• evaluate TI in PCV

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Volume vs. TimeVC

SIMV (VC)

N = end inspz = TE

P = end expM = delivery of VTy = pause

O = exhalation of VTL = start of inspx = TI

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Volume vs. TimePC

SIMV (PC)

N = end insp

P = end expM = delivery of VTz = TE

O = exhalation of VTL = start of inspx = TI

Graphics

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Volume vs. TimeVT

t

if Insp VT ≠ Exp VT = ?

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Volume vs. Time• Summary - Use VT graphics to:

• ID leaks in the ventilator system• ID air-trapping

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Flow-Volume Loops

D = PEFRB = PIFR

C = end insp/start expA = insp start/end exp

VCSIMV(VC)

Graphics

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Flow-Volume Loops

D = PEFRB = PIFR

C = end insp/start expA = insp start/end exp

PCSIMV(PC)

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Flow-Volume Loops

Normal Abnormal

•Tracing should start at zero and end at zero

•If not =

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Flow-Volume Loops• Gauge effect of bronchodilator therapy

flow

VT

flow

VT

Before After

Graphics

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Flow-Volume Loops• Summary - Use FV Loops to:

• ID leaks in the ventilator system• ID air-trapping• Evaluate the effect of bronchodilator

therapy

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Volume-Pressure Loops

AC = CD slope

CDA = expiration

ABC = inspiration

E = vol end insp

D = exp press level

C = end insp/start exp

B = insp press level

A = start insp/end esp

MandatoryVentilatorBreath

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E = expiration

I = inspiration

SpontaneousBreathVT

P

E

I

Volume-Pressure Loops

Graphics

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Volume-Pressure Loops

VT

P

1

2

1 = normal

2 = slope ↓, shape is same⇓

What happened?

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Volume-Pressure Loops

VT

P

1 2 1 = normal

2 = slope ↓, widens⇓

What happened?

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Volume-Pressure Loops

VT

P

Duck bill thingy(P ↑ w/o change in VT)

Graphics

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Volume-Pressure Loops

alveolar re-expansion interval

• Re-expansion interval(big press/little vol) -shows high press neededto open alveoli

• Rx?

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Volume-Pressure Loops• Summary - Use VP Loops to:

• ID breath type• Assess work to trigger breath• Assess WOB• Assess CL and RAW• Detect overdistention• Titrate PEEP