Mechanical Ventilation Ch. 7-10

Front 1

What is the primary goal of mechanical ventilation?

Back 1

to support the minute ventilation (VE) to meet the O2 and CO2 requirements for patients who cannot do so themselves.

Front 2

What are the main parameters?

Back 2

VT, RR (f), which combined make up the minute ventilation

Front 3

What are the initial ventilator settings during volume ventilation what needs to be considered?

Back 3

1. Minute ventilation (VE) = VT x RR (f)
2. Inspiratory gas flow
3. Flow waveform
4. Inspiratory and expiratory (I:E) ratio
5. Pressure limit
6. Inspiratory hold (pause)
7. Inspiratory and Expiratory pressure (PEEP)

Front 4

What is the primary goal of VV?

Back 4

to achieve a desired VE that matches the patient's metabolic needs and accomplishes adequate gas exchange.

Front 5

How do you calculate VE?

Back 5

Men VE = 4 x BSA
Women VE = 3.5 x BSA

Front 6

How do you calculate IBW?

Back 6

Women = 105 + 5(H-60)
Men = 106 + 6(H-60)

Front 7

What are the normal Vt for adults and infants?

Back 7

Vt = 6-12 ml/kg of IBW (adults)
Vt = 5-10 ml/kg of IBW (infants and children)

Front 8

What are the recommended tidal volume for normal lungs?

Back 8

10 to 12 ml/kg with RR 8 -12

Front 9

What are the recommended tidal volume for COPD/Asthma?

Back 9

8 to 10 ml/kg with RR 8 - 12

Front 10

What are the recommended tidal volume for Restirctive Diseases?

Back 10

4 to 8 ml/kg with RR 15 - 25

Remember: high rates may not provide enough time for exhalation resulting in intrinsic PEEP

Front 11

What is the desired Plateau Pressure?

Back 11

less than 30 cm H2O

Front 12

Why are Vt's for more than 12 ml/kg not recommended?

Back 12

because the risk of high pressures and accompanying overdistention and trauma to the lung as well as other complications.

Front 13

Low volumes (4 to 8 ml/kg) for restrictive diseases prevent?

Back 13

high pressures and alveolar distention

Front 14

Low volumes less than 4ml/kg?

Back 14

atelectasis

Front 15

What is tubing compliance (CT)?

Back 15

the amount of gas compressed in the ventilator circuit for every centimeter of water pressure generated by the vent during the inspiratory phase.

Front 16

How do you calculate CT?

Back 16

Change in pressure/change in pressure

Front 17

What is compressible volume?

Back 17

the volume of gas in the circuit

Front 18

Define VDmech:

Back 18

the volume of gas that is rebreathed during ventilation

Front 19

What adds VDmech while ventilating a pt?

Back 19

Flex tubing (6 inches)
Y-connector may add 75ml
HME may add 20 to 90ml

Front 20

What reduces the VDmech while ventilating a pt?

Back 20

ETT slightly reduces VDmech about 1ml/kg IBW

Front 21

For some VV practitioners set?

Back 21

f, Vt and flow

Front 22

Some VV require what to be set?

Back 22

rate, inspiratory time percent (Ti % of TCT), and VE

Front 23

It is important to understand the interrelation of:

Back 23

inspiratory flow, inspiratory time, expiratory tiem and I:E ratio

Front 24

Formula for Total Cycle Time (TCT)

Back 24

Ti + TE

Front 25

Formula for rate

Back 25

1min/TCT = 60sec/TCT (secs)

Front 26

Formula for TCT

Back 26

60sec/ f

Front 27

Formula for I:E

Back 27

Ti / TE

Front 28

What is an inverse I:E ratio?

Back 28

2:1 or 3:1. Expiratory time takes on the value of 1.

Front 29

What are the complications of an inverse I:E ratio?

Back 29

mean airway pressure

Front 30

Formula for Ti?

Back 30

Vt/flow
Ti can be determined when Vt and flow are known and the flow pattern is constant or square waveform.
Note: flow control calibrated in L/min so convert to L/sec.

Front 31

Formual for Vt:

Back 31

flow x Ti

Front 32

Formula for flow:

Back 32

f = Vt/Ti

Flow can be determined if Vt and Ti are known.

Front 33

The clinician has the option to select flows and flow patterns on the ventilator.

Back 33

In VV

Front 34

The flow setting on a mechanical ventilator estimates the delivered flow of?

Back 34

inspired gas
(Rate of gas flow)

Front 35

High flow shorten Ti resulting in?

Back 35

higher peak pressures adn poor gas distribution

Front 36

Slow flow rates may:

Back 36

reduce peak pressure
improve gas distribution
increase Paw at the expense of increasing Ti (result may cause cardiovascular side effects and shorten TE leading to air trapping)

Front 37

Normal range for short Ti for normal lungs?

Back 37

0.8 to 1.2 seconds

Front 38

Normal I:E ratio?

Back 38

1:2 or less (usually 1:4)

Front 39

What is the initial peak flow?

Back 39

about 60L/m (40-80L/min)

Front 40

Longer Ti show to improve?

Back 40

ventilation in nonhomogeneous lungs (ARDS) (taking 3 to 4 time constants)

Front 41

Fast flow is beneficial for pt's with?

Back 41

increased airway resistance (Raw)
i.e. COPD thus giving a longer TE and preventing or reducing air trapping

Front 42

In selecting waveforms, the clinician must decide what?

Back 42

if the Paw is more important for the patient than concerns of high peak inspiratory pressure.

Front 43

True or False
High peak pressure may not always increase the risk of damage to the lung parenchyma.

Back 43

True

(Pt's with acute asthma w/severe bronchospasm, mucosal edema, and increased secretion production)

Front 44

What will changing the waveforms do?

Back 44

can vary the peak flow delivered and the distribution of flow

Front 45

True or False
In volume cycled machines, changes from constant to another flow pattern does change the peak flow selected.

Back 45

False (does not)

It does change the Ti and the I:E ratio

Front 46

In normal lungs, flow pattern is probably not of key importance. What flow patterns are?

Back 46

descending and constant

Front 47

Descending flow pattern may be beneficial by keeping peak pressures low and Paw high, and improving gas distribution for what types of pt's?

Back 47

hypoxemic and low lung compliance patients

Front 48

The descending pattern is more likely to deliver a set Vt at a lower pressure and provide for better distribution of air through the lung than a constant or an accelerating flow. What type of pt?

Back 48

patients with high Taw

Front 49

PaO2 decreases and PaCO2 increases while VE increases may be the result of?

Back 49

auto PEEP, poor ventilation to perfusion matching adn changes in venous return.

This may require changing gas flow and/or pattern, Vt, f, or I:E ratio

Front 50

What are used to determine Plateau pressure?

Back 50

inflation hold or end-inspiratory pause

Front 51

Inspriatory pause helps improve what?

Back 51

the distribution of air throughout the lungs regardless of the type of flow pattern used, and to provide optimum ventilation/perfusion (V/Q) matching and reduce VD/Vt

Front 52

Pressure targeted ventilation provides:

Back 52

a set pressure to the patient during breath delivery while tidal volume can vary from breath to breath

Front 53

Types of pressure ventilation:

Back 53

PSV, PCV, BiPAP, dual control mode (pressure augmentation), VAPS, PRVC, VS

Front 54

BiPAP

Back 54

bilevel positive airway pressure

Front 55

VAPS

Back 55

volume assured pressure support

Front 56

PRVC

Back 56

pressure regulated volume control

Front 57

VS

Back 57

volume support

Front 58

What is the advantage of PV?

Back 58

provides flow on demand and potentially limiting pressures to avoid overinflation

Front 59

In PV, initial flows may cause?

Back 59

frictional forces (shearing) between adjacent alveoli with differing lung inflation characteristics (time constants)
Vt vary based on lung characteristics

Front 60

To help preserve normal FRC an approptiate minimum level of PEEP would be?

Back 60

3 to 5 cm H2O

Lack of physiologic PEEP may cause atelectasis

Front 61

Low PEEP may be beneficial in patients with?

Back 61

COPD who would normally pursed lip breath but cannot in an ETT

Front 62

PSV goal if:

Back 62

1. Help increase Vt (5 to 12ml/kg)
2. Decrease RR (less than 25 to 30bpm
3. Decrease WOB through artificial airway

Front 63

A cycle criteria of 40% of peak low is an appropriate starting point for what type of pt's?

Back 63

COPD patients

Front 64

Initial settings for PCV are?

Back 64

Rate, inspiratory time, and I:E ratio
the pressure gradient (PIP-EEP) is adjusted to establish volume delivery based on lung characterisitics and effort
PIP -5cmH2O as starting point
10 to 15 cmH2O

Front 65

What type of waveform does PCV normally provide?

Back 65

descending ramp waveform

adjust rise to meet pt needs
assess Ti

Front 66

PCV is shown to improve what?

Back 66

oxygenation and gas exchange, Paw, facilitate lung healing and reduce PIP, PEEP, VE, respiratory work, need for sedation, and ventilation time

Front 67

What are the BiPAP initial settings?

Back 67

5 to 10 cmH2O, increase in increments of 3 to 5 cmH20 until a rate of 25 bpm or lower is achieved adn Vt is 7ml/kg or more.

Front 68

What are the EPAP initial settings?

Back 68

2 to 5 cmH2O adn increased in increments of 3 to 5 cmH2O.

Front 69

Initial settings of Dual Control Pressure Ventilation w/Volume Targeting?

Back 69

provides the benefits similar to PV.
VAPS and PAug less familiar. Suggested initial settings.
PS with a descending flow pattern may be implemented.
Volume mode must be selected VC-CMV (assist) or VC-SIMV.

Front 70

Initial settings for VAPS or Paug?

Back 70

Target volume selected based on VV criteria.
Sensitivity set (flow or pressure) so that patient can trigger a breath.
Set upper pressure limit (max safety limit), i.e. 40 cmH2O
PIP for breath delivery is set to provide the majority of the Vt (set P = Pplateau - PEEP)
Baseline pressure set the same as VV
Activate Paug (or VAPS)
Set the flow waveform on rectangular and set inspriatory gas flow setting so that the pressure/time and flow/ time graphics produce the desired effect.

Front 71

Flow pattern and flow delivery important in Paug. What is the criteria for setting flow?

Back 71

1. flow must be set hight enough so tha tTi does not last longer than Ti for a mandatory, unassisted volume breath.
2. Flow must be set so that the pressure waveform during a Paug breath is rectangular at the beginning of inspiration and has a small pressure rise at the end of inspiration for some breaths.
3. the rectangular flow waveform should be selected becasue use of the descending ramp flow reduces some of the advantageous effects of the augmented breath and prolongs inspiration.

Front 72

Initial settings of Pressure Regulated Volume Control (PRVC)?

Back 72

provides closed loop pressure breaths and targets the pressure to achieve the set volume.
it is pressure limited, time cycled mode that uses the set Vt as a feedback control.
the operator sets a Vt to be delivered that is appropriate for the patient. Baseline pressure and pressure limit are also set.
Ventilator delivers one or more test breaths. (sometimes pressure targeted breath or volume targeted breath)
Ventilator calculates Cs adn Raw in order to determine the pressure required to achieve the set Vt.
Ventilator progressively adjusts the pressure level unitl set Vt is achieved.
Ventilator will stop pressure delivery at 5 cmH2O below max pressure limit.

Front 73

Why is it important to set an upper pressure limit in PRVC?

Back 73

1. provides the upper limit for the ventilator.
2. if patietn coughs or forcibly exhales during the inspiratory phase, the ventilator will not permit pressure to exceed the upper pressure limit.

Front 74

Initial settings of Volume Support?

Back 74

purely a spontaneous mode.
operator set sentitivity, Vt, and upper pressure limit. So Vt based on VV criteria. (Set Vt is the min. Vt)
less pressure required as lungs improve
Backup mode for apnea

Front 75

Mandatory Minute Ventilation

Back 75

operator set the minimum parameters (Vt, f, and high and low pressure alarms)
ventilator adjust according to patient needs.

Front 76

Selection of FiO2

Back 76

goal is to achieve acceptable PaO2 between 60 to 100mmHg

Front 77

What is the formula for estimating desired FiO2?

Back 77

PaO2(desired) x FiO2(known)
-------------------------------------------
PaO2(known)

Front 78

Sensitivity

Back 78

-set so that patients can easily flow or pressure trigger a breath.
-Flow triggering: 1 to 10L/min below base flow. (manufacturer/operator set)
-Pressure sentitivity: -1 to -2 cmH2O
-Flow triggering now the preferred method for triggering because it has a faster response time.

Front 79

Humidification

Back 79

-Normal spont. breathing provide 100% RH at 37 degrees centigrade adn contains 44 mg/L of water.
-Conditioning typically occurs down to the fourth or fifth genteration of subsegmental bronchi and is called the Isothermic saturation boundary.

Front 80

Types of Humidifiers:

Back 80

1. Passover
2. Vapor phase
3. Wick
4. Active Heat adn Moisture Exchange

Front 81

Heat Moisture Exchangers (HME)

Back 81

artificial nose
can add 10 to 14mg/L of water
hygroscopic HME (HHME): 22 to 34mg/L
resistance to flow (accumulates moisture and secretions) in extended use.
HME add mechanical deadspace (50-100ml)
change every 2-3days
watch for thickening secretions
ET occulusion in greater than 7days.

Front 82

Alarms

Back 82

-low pressure 5-10cmH2O below PIP
-High pressure 10cmH2O above PIP
low PEEP/CPAP 2 to 5 cmH2O below set PEEP/CPAP
apnea alarm: set no mor ethan 20 sec.
ratio alarm: warns when Ti is mor than TCT
low Vt: 10 to 15% below set Vt
low exhaled VE: 10 to 15% below average VE
FiO2 5% above and below set FiO2

Front 83

Action during Ventilator Alarm Situations

Back 83

1. ensure pt is being ventilated
2. when in doubt disconnect pt and manually ventilate
3. cannot correct problem, replace ventilator
4. operating manual may assist with troubleshooting
5. final resort-call local company rep.

Front 84

Ventilation Setup

Back 84

check/calibrate ventilator
fill humidifier
adjust alarms
verify monitoring
emergency equipment in close proximity
check suctioning equipment

Front 85

Initial Ventilator Settings for COPD

Back 85

-non-invasive ventilation is possible
-VC or PC-CMV to relieve increased WOB
-Adjust peak flow to meet pt's demand
-Vt 8 to 10ml/kg with RR 8 to 12bpm
Ti 0.6 to 1.2sec
PEEP approx. 5 cmH2O
-Monitor hyperinflation (auto-peep) by setting the lowest possible VE that produces acceptable gas exchange (Pt. baseline PaCO2)
-Provide the longest expiratory time possible
-if pt. initiating inspiration, and auto-peep noted, set PEEP near 80% of the auto-peep level (3-5cmH2O)
-Plateau pressure should be monitored and maintained less than or equal to 30cmH2O to avoid alveolar over distention. (May req. sedation)
-PaO2 at 55 to 75mmHg

Front 86

Neuromuscular disorders

Back 86

-full or partial support
-negative or PPV
-noninvasive or invasive ventilation
-Assist/Control mode (CMV)
-Volume ventilation
-High Vt (12 to 15ml/kg)
F = 8-12bpm
-Inspriatory flow rates approx. 60 lpm (1sec Ti)
-Constant or descending waveform
-PEEP 5cmH2O/ FiO2 21%

Front 87

Guidelines for Asthma

Back 87

-VC or PC-CMV
-keep peak and plateau pressures at min.
-FiO2 to keepp PaO2 600-100mmHg
-Permissive hypercapnia (PaCO2 45-80mmHg)
-Possibly use sedation and paralytic
-PEEP to apporx. 80% of auto PEEP
-Long TE: RR 8 or less, Vt 4 to 8ml/kg; Ti less than 1 sec.; peak flow 80 to 100 lpm with descending flow waveform

Front 88

Guidelines for Closed Head Injury

Back 88

-Protect airway due to ALOC
-V-CMV or P-CMV (watch pressures)
-Monitor ICP and Hypoxemia
-Vt 8 to 12ml/kg; plateau pressure about 30cmH2O
-RR 15 to 20bpm (avoid auto-peep)
-initial FiO2 at 100. Titrate to keep PaO2 70 to 100mmHg. Ti 1sec/descending waveform
-PEEP 0-5cmH2O

Front 89

Adult Respiratory Distress Syndrome

Back 89

-PC or VC-CMV
-SaO2 88 to 90%. FiO2 titrated/begin @100%
-May need to sedate or paralyze
- High PEEP (15cmH2O or greater)
-Plateau pressure less than 30cmH2)
-Permissive hypercapnia

Front 90

Guidelines for CHF

Back 90

-Select mode that reduces WOB
-May use non-invasive mask for NPPV or CPAP to improve oxygenation.
-Consideration of PPV and hemodynamics
-VC or PC-CMV recommended
-Vt 8-10ml/kg; f 10 or above; Peak flow 60 lpm; Ti 1 -1.5sec
- PEEP 5 to 10cmH2O
- FiO2 100 then titrate to keep SpO2 90-92%
-Monitor ABG's, urine output, SpO2, Hemos

Front 91

Patient Evaluation

Back 91

-observation by well trained, caring clinician
-check physician orders
-operational verification procedure (OVP)
-overall check of equipement (vent, circuit, humidifier)

Front 92

AARC guideline for documentation of Pt ventilator system:

Back 92

1. Data recorded on appropriate form
2. Pt/vent system check
3. Physician orders
4. Brief narrative of clinical observation

Front 93

First thirty minutes

Back 93

-assess B/S
-check vitals
-check alarms
-ABG
-chest xray
-ventilator check

Front 94

Documentation Guidelines

Back 94

-mode
-sensitivity
-Vt, rate, VE
- corrected tubing compliance
-alveolar ventilation
-dead space
-mechanical deadspace (Added)
-final alveolar ventilation VA = (Vt-VDant-Added VDmech) x f

Front 95

Monitoring Airway Pressure

Back 95

Peak inspiratory pressure (PIP
Plateau pressure
Set pressure (PC)
PIP-Pplateau= Transair press
End expiratory pressure
Mean airway pressure
Pressure Limit
Low pressure alarm
Circuit assessment for leaks

Front 96

Vital Signs, Blood Pressure, and Physical Exam of the Chest

Back 96

-ECG-noninvasive means of continuously monitoring HR and rhythm
-Temp
-Systemic arterial blood pressure
-Central venous pressure
-Pulmonary artery pressure
-Chest exam (inspection, palpation, percussion, and auscultation)

Front 97

Management of ET and Tracheostomy Tube Cuffs

Back 97

check every 8-12hrs
keep below 20 to 25mmHg/ 27-34cmH2O to reduce risk fo tracheal damage.
Use MLT whenever possible

Front 98

Cut in the Pilot Tube

Back 98

Accidental cuts/punctures are common occurances
1. Manufacturer designed blunt tipped needle device used as one solution
2. Stop cock method
3. Exchange ET tube

Front 99

Tube and Mouth Care

Back 99

ETT respositioned every 8 to 12hrs
Mouth care done routinely (VAP's)

Front 100

Monitoring Compliance and Airway Resistance

Back 100

-Normal Cs: 70 to 100ml/cmH2)
-Assess for changes in lung condition
-CD decreases whenever Cs decreases or Raw increases.
-Raw 0.6-2.4cmH2O/L/sec. Treatment of Raw must be directed at the specific cause of increase (i.e. sx, clearing obstruction, or bronchodilator)

Front 101

Bedside Measurement of Pressure Volume Curves

Back 101

daily evaluation of the pressure volume relationship (either static or dynamic) is recommended to tract progression of lung and airway changes.

Front 102

Comment Section of the Venitlator Flow Sheet

Back 102

-Pt assessment (B/S, skin color, LOC)
-Changes in ventilator settings
-Changes in physician's orders
-Description of any equipment problems
-STOP (Subjective, Therapeutic Objective, and Plan)

Front 103

Ventilator Graphics

Back 103

-Provide immediate visual infromation about the pt-vent. interaction
- Provide a graphic record of pathophysiological changes
-Graphics assists in monitoring the functioning of the ventilator and evaluation of the pt's response to the ventilator and to help the clinician adjust the ventilator settings

Front 104

Scalar:

Back 104

used to specify the waveforms for pressure, flow, and volume that are graphed against time (i.e. pressure, flow and vol scalars)

Front 105

Loop:

Back 105

describes the type of graph (displays of 2 variables). Ex: pressure-vol adn flow-vol loops

Front 106

Name the waveforms for pressure:

Back 106

rectangular, exponential (rise)

Front 107

Name the waveforms for volume:

Back 107

Ascending ramp, sinusoidal

Front 108

Name the waveforms for flow:

Back 108

rectangular, sinusoidal, ascending ramp, descending ramp, exponential (decay)

Front 109

The formula for resistance:

Back 109

change in pressure/flow

Front 110

Monitoring Data

Back 110

-Flow and pressure monitors on the inspiratory side of the ventilator just before the point where gas exits the ventilator and goes to the patient.
-Flow and pressure monitors on the expiratory side of the ventilator just as gas enters the ventilator through the exhalationi valve.

Front 111

Relationship of Pressure, Volume, Flow and Time

Back 111

1. Volume = Flow x Ti
2. The flow of gas into the lungs depends on the difference between the pressure from the power source (the ventilator) and the pressure inside the lungs. (Flow = V/Ti)
3. The amount of pressure required to inflate the lungs depends on lung compliance and airway resistance.

Front 112

Volume Ventilation (Constant Flow)

Back 112

-Force required to deliver air to lungs with or without decreased compliance or increased airway resistance.
- High internal resistor: placed in-line between the gas source and lungs to regulate the amount of flow.
- High pressure source prevents back pressure.

Front 113

Auto PEEP

Back 113

-Expiratory pause allows direct measurement of auto-peep
-Some ventilators give total which is the sum if auto-peep and set peep

Front 114

Characteristics of VV with any Fixed Flow Pattern

Back 114

- the flow waveform provided, regardless of type, does not change shape during inspiration even with changes in lung characteristics.
-the flow waveform remains the same from breath to breath
- volume delivery remains constants as long as the breath is volume cycled.
-pressure patterns at the upper airway vary with changes in CL and Raw and the type of flow pattern selected.

Front 115

Pressure Ventilation

Back 115

-(PC-CMV) the operator sets a pressure to be delivered to the pt's lungs. Flow and Vt vary.
-Ventilator attmepts to provide a set pressure from start of inspiratory until expiration begins producing a nearly constant pressure waveform.

Front 116

PV with Constant Pressure Waveforms

Back 116

4 important characteristics:
1. rectangular (constant)
2. pressure waveform not affected by changes in lung characteristics or pt flow demand
3. the rate of flow delivery varies according to the lung characteristics, set pressure, and inspiratory effort.
4. the flow waveform rises rapidly at the beginning of inspiration and decreases during inspiration (continuously variable decelerating pattern)

Front 117

Pressure Ventilation vs. Volume Ventilation

Back 117

VV: constant flow (rectangular pattern)
PV: flow waveform is a descending curve which vaires with lung characteristics and patient flow demand. (continuously variable decelerating waveforms)
VV: Pressure curve resembles ascending ramp or rising exponential curve.
PV: pressure curve rectangular (Ti long enough)
VV: the pressure waveform changes with changes in lung characteristics (Cs, and Raw)
PV: changes in Cs and Raw change flow and volume delivery but the pressure waveform remains the same.

Front 118

Inspiratory Rist Time Control: Sloping or Ramping

Back 118

-pressure breath produce high flow at the beginning of inspiration.
-small ET tubes or Raw create turbulent flow
-pressure spike can occur at the beginning of the pressure curve before the pressure adjusts to the set value
-flow and pressure delivery can be tapered at the start of inspiration adn thus reduce the spike.
-insp. flow delivery during PCV, can be adjusted with inspiratory rise time control aka slope control.
-slope/rise time function controls the rate at which the flow valve opens.

Front 119

Rise/Slope Function

Back 119

-adjusting inspiratory rise slows or speeds the rate at which pressure and flow exit the ventilator for a specific period.
-the adjustment may make the breath more comfortable
-matches ventilatory breath delivery with pt flow demand thus improve pt ventilator synchrony and decrease WOB

Front 120

Rise Time/Slope Function Caution

Back 120

too much tapering of flow and pressure delivery can reduce Vt and cause pt ventilator dyssynchrony

Front 121

Pressure Support Ventilation

Back 121

-is a pt triggered, pressure targeted, flow cycled mode of ventilation.
-as lung characteristics deteriorate, pressure remains constant/volume delivered decreases.
-operator sets pressure, sensitivity, inspiratory rise time (slope), and inspiratory flow cycle value, (aka flow cycle pattern)

Front 122

Flow Cycling During PSV

Back 122

-flow cycling occurs when the ventilator detects a decreasing flow which represents the end of inspiration.
-appropriately set flow cycling percent varies with pt's
-COPD pt's or pt's with increased Raw may require higher flow cycle percents (40%)

Front 123

Automatic Adjustment of Flow Cycle Criterion

Back 123

-difficult to adjust flow cycle criterion due to frequently changing lung mechanics (Cs and Raw)
-software program available in some ventilators (unavail. in the US)

Front 124

Pressure Volume Loop

Back 124

-another graphic available on newer vents.
-pressrue and volume determine compliance and continuous gas flow during the curves also provide information about Raw.

Front 125

Spontaneous Breaths and P-V Loops

Back 125

-a practitioner can learn to distinguish mandatory breaths from spontaneous breaths by observing the way the P-V loop is created during breath delivery.
-spont.: trace clockwise
-positive pressure breath: counter clockwise tracing

Front 126

Flow Volume Loops during Mechanical Ventilation

Back 126

-F-V loops used for various purposes.
-inspiration is above the baseline
-exhalation is below the baseline
-Peak Expiratory Flow Rate (PEFR) is one of the parameters measured on the F-V loop. It is the highest value on the expiratory flow curve.

Front 127

Troubleshooting F-V Loops During Mechanical Ventilation

Back 127

-the F-V loop can be used to detect leaks and air trapping (auto-PEEP)