Test 5 Flashcards by meagan robinson

Monitoring lung and chest wall compliance

Compliance testing for inflection points

- Static compliance

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Compliance testing for inflection points

Deliver set volume and measure pressure, add a set volume and pressure until full
Plot these points and look for lower inflection point and upper inflection point
Ventilate with PEEP slightly above inflection point and / or plateau pressure below upper inflection point

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Static compliance

^V/^P

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Two kinds of compliance

Dynamic and Static
-static is the more common
Dynamic: Peak
Static: insp hold/ pause/ plateau

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Corrected Vt

corrected tidal volume should be used because you want to use only the volume to the lung, not the circuit
Try to use the Vt and Plat from the same breaths
-AutoPEEP should be measured and used if possible

Corrected Vt/ Plat-PEEP=Clst

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What does static compliance tell us

stiffness of the lungs and chest wall

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Compliance values for intubated pt

Norm 70-100 unusual for vent pt
mild 40-70
moderate 30-40
Severe <30
ARDS <25 unweanable

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Whats most important when looking for changes in lung status

Trending values (plat)

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Airway resistance equation

^Pressure/ ^flow (V) ((lpm-> L/S=cmH2O/L/s))

Peak pressure-Plateau pressure/ Peak Flow (L/s)
or just
Peak - Plateau

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Ranges for Airway Resistance

norm 0-10cmH2O/L/s
moderate 11-15
severe >15

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Airway pressure ranges

Peak: great concern over 50
Plateau: kept below 30-35 (below 30, O2 problems)
-consider PCV if pressure excessive
-Mean airway pressures increase for better oxygenation reduce to keep side effects down to a minimum

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Mean Airway Pressures

increase for better oxygenation, reduce to keep side effects down

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AutoPEEP

air that is not exhaled before next breath

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Best way to tell if there is auto PEEP

check the flow/time curve
-if flow does not return to baseline, pt has autoPEEP
(this does not give you a number)
Do autoPEEP maneuver to get actual number (exp.hold)

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How to fix Auto PEEP, increase expiratory time. how?

Shorten Ti(pt. with obstructive airways) 
-will go in faster, increasing pressures
Decrease RR, lengthen resp cycle
-Change CO2 and pH 
Decrease Vt, less to exhale
Increase flow rate,
-square waveform
SIMV mode
match PEEP

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Inverse I:E when

ARDS, improve O2

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Monitor breathing efforts and patterns, Work of breathing

small airway:us as large ETT as possible
system imposed: effort to open valve to initiate breath(demand valves)
Use flow sensitivity
PSV
sensitivity set appropriately
keep flows set appropriately
keep Raw low, bronchodilators, suction, etc
treat cause of MV

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Monitoring breathing efforts and patterns

WOB
Esophageal pressure monitoring:amount of pressure within chest
Oxygen cost of breathing: Paralyze pt, O2 is used on important organs
Assessing ventilatory drive, daily spontaneous breathing trial: decreasing pt problems, extubate ASAP

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Vent Checks, monitoring for

integrity of the airway and circuitry, including secretions
The prescribed settings and assess for appropriateness
Acceptable gas exchange values
Respiratory system mechanics
Comfort and synchrony of breathing of the patient
Setting of alarms
Other safety issues

Flow Rate problems

Look for flow pattern to be even and pt not trying to exceed the set fl

Trigger Problems

Excessive pt effort right before breath starts
Deflection on pressure/time curve is pressure triggering
Doesn’t happen as much on flow triggering

Cycle Problems

Double breathing or breath stacking, too small volume?Forcing exhalation if breath taking too long for patient (Ti)

Assessing Graphics- Volume/ Pressure Loop

Look for inflection point to set PEEP

Look for beaking to assess overdistension

Assessing Graphics- Flow/ Volume Loop

Just like the FVC loop on PFT
Look for faster flows to assess airways
Pre and post bronchodilator assessment

Trouble shooting-Causes of sudden respiratory distress, Patient:

``` Airway Pneumothorax Secretions Anxiety Asynchrony ```

Trouble shooting-Causes of sudden respiratory distress, Vent:

``` Leak(ETT, Humidifier, Tubing connections) Trigger Flow Circuit Asynchrony ```

Imminent death

Consider removing airway if you think it is an airway problem CXR(if time) or needle if think it is a pneumo Could be non-respiratory, continue to bag until issues addressed When all patient and mechanical causes can be eliminated then consider sedation Paralyze patient only if absolutely necessary

After the patient has been physically assessed, the mechanical ventilator should be checked routinely to ensure that:

Settings are correct Ventilator is meeting the patient's needs Circuit is not compromised Alarms are set and functioning -Ventilator waveform analysis of flow, volume, and pressure may reveal such problems as leaks in the system, inadequate ventilator sensitivity, lung overdistension, and many other problems.

If inspiratory time is constant, as in the case of a paralyzed patient, who is breathing at a set rate of 16 bpm, the square flow pattern results in

higher peak airway pressures (PIP) than the decelerating flow pattern. -Thus if a square waveform was initially selected and PIP were high (pressure is variable during volume control), a change to a decelerating ramp waveform would reduce the PIP, keeping in line with our lung-protective ventilation strategies to try to prevent VILI.

Auto-PEEP can be assessed directly by most modern ventilators through the use of an

exp hold maneuver | -It can also be detected on the volume, flow, and pressure waveforms.

The volume waveform can quantify

the amount of volume that is being trapped.

The flow waveform will demonstrate

incomplete exhalation prior to a subsequent breath through failure of the flow waveform returning to baseline.

Auto-PEEP can be corrected by

extending the expiratory time, or compensated for by setting PEEP close to auto-PEEP levels to reduce the excessive trigger effort required by the patient.

Alarms

High/low volume = 10% or 100 mL above/below set value High/low V̇e = 20% or 1 to 2 L above/below set value High/low PIP= 10 cm H2O above/below PIP High/low Fio2 = 5% above/below set Fio2 High RR = 10 breaths above Apnea time = less than 20 seconds

There are many factors that contribute to Paw during mechanical ventilation, including:

PIP PEEP I:E ratio Flow

norm Ti

0.8-1.2

The major ventilator parameters that are typically included in a written order are

``` Ventilator mode Tidal volume (Vt) or inspiratory pressure (Pi) Respiratory rate (RR) Fraction of inspired oxygen (Fio2) PEEP ```

norm inspiratory flow rates

40-100

Patients who will be receiving mechanical ventilation under emergent conditions will display signs of the four major indicators for mechanical ventilation:

Acute ventilatory failure Impending ventilatory failure Severe oxygenation defects Apnea

Static compliance represents

lung compliance during periods of zero air flow, and as such, uses Pplat in its equation.

Dynamic Compliance represents

lung compliance during periods where gas flow is present, and as such, uses PIP in its equation.

With increased resistance,

PIP rises and Pplat remains the same.

With decreased compliance, PIP

PIP rises and Pplat rises a commensurate level.

What ventilation parameters are used to evaluate a patient's lung compliance?

AutoPEEP PEEP PIP Plat

What impact will increased airway resistance due to secretions or bronchospasm have on airway pressures monitored during mechanical ventilation?

Increased PIP, unchanged Pplat

Asynchrony can be categorized in accordance with its cause:

Trigger asynchrony Flow asynchrony Cycle asynchrony