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Flashcards in Starting Mechanical Ventilation Deck (79)
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1
Q

When to move from CPAP to MV

A

When on CPAP move to mechanical ventilation when

SaO2< 85% at an

FiO2< 40-70%

and PEEP of 5-10 cmH2O

2
Q

Indications for Mechanical Ventilation in Adults

A

ASIA

Apnea

Severe Refractory Hypoxemia

Impending ventilatory Failure

Acute Ventilatory Failure

3
Q

Indications for Mechanical Ventilation in Adults

Severe Refractory Hypoxemia

A

A-a Gradient (mmHg)

  • Normal
    • 25-65 On FiO2 1.0
    • 5-20 On Room Air
  • Critical
    • >350 On FiO2 1.0

PF Ratio

  • Normal
    • 350-450
  • Critical
    • <200

PaO2/PAO2

  • Normal
    • 0.75-0.85
  • Critical
    • <0.15
4
Q

Indications for Mechanical Ventilation in Adults

Impending Respiratory Failure

A

Assess WOB and other relevant parameters

MIP (cmH2O)

VC (mL/kg)

Vt (mL/kg)

RR (bpm)

Vd/Vt

5
Q

MIP (cmH2O)

A

Normal -80 to -100

Critical 0 to -20

6
Q

VC (mL/kg)

A

Normal 65-75

Critical <10

7
Q

Vt (mL/kg)

A

Normal 4-8

Critical <4

8
Q

RR (bpm)

A

Normal 12-20

Critical >35

9
Q

Vd/Vt

A

Normal 0.25-0.4

Critical >0,6

10
Q

Indications for Mechanical Ventilation in Adults

Acute Ventilatory Failure

A

PaCO2> 55 mmHg and a pH >7.25

11
Q

Indications for Mechanical Ventilation in Adults

A
  • Apnea
  • Respiratory Failure
    • pH < 7.20
    • PaO2< 50 mmHg
    • PaCO2>65 mmHg
    • We will seldom wait for this clinically and instead initiated mechanical ventilation sooner
  • Pulmonary Disease
  • Neurological and Neuromuscular
  • Congenital Abnormalities
  • Post Surgery
12
Q

Classic Indications for Mechanical Ventilation in Infants

A
  • Classic indications of mechanical ventilations in infants with respiratory failure or persistent apnea
  • Respiratory Failure
    • Arterial blood pH <7.20
    • PaCO2 of 60 mmHg
    • Oxygen saturation of 85% at oxygen concentration of 40-70% and CPAP of 5-10 cmH2O
13
Q

Extremely low body weight infants and mechanical ventilation

A

In extremely low body weight (ELBW) infants (weighing <1000g) intubation and positive pressure ventilation (PPV) may be necessary immediately after birth

14
Q

Infants with Mechanical Ventilation just admitted to NICU

A
  • Generally once the infant is stabilized in the NICU a pressure limited ventilator using a sinusoidal flow pattern is used. The settings that are commonly used are the following
  • If a longer Ti is required before surfactant administration, it should be lowered to 0.3 seconds after surfactant is administered
15
Q

Infants Mechanical Ventilator Modes

A

Ventilator modes such as synchronized intermittent mandatory ventilation (SIMV) or assist control modes can reduce WOB and blood pressure fluctuations if the sensitivities are properly set

Modes that maintain a consistent Vt can reduce risk of volutrauma (damage caused by overdistention by mechanical ventilation set for excessively high Vt) particularly after the administration of surfactant

High frequency ventilation may be indicated in infants who cannot be ventilated with the usually effective FiO2 levels, ventilator pressures, and rates

16
Q

Sponataneous Parameters in Adults

A

RR (bpm) 12-20

Vt (ml/kg) 4-8

VC (ml/kg) 65-75

Resistance (cmH20/L/sec) 0.6-2.4

Compliance (mL/cmH2) 50-170

17
Q

Sponataneous Parameters in Neonates

A

RR (bpm) 30-60

Vt (ml/kg) 5-7

VC (ml/kg) 35

Resistance (cmH20/L/sec) 25-50

Compliance (mL/cmH2) 1-2

18
Q

What is different between neonates and pediatrics

A
  • Faster RR
  • Smaller VC
  • Much, much higher airway resistance
    • Think of how small the diameter is and this will increase resistance to the 4th power
  • Much, much lower compliance
  • This is normal
  • Preemies will have even worse compliance as they develop RDS
19
Q

GOALS OF MECHANICAL VENTILATION

A

Improve oxygenation to meet the metabolic demands of the body

Eliminate CO2

Reduce work of breathing

20
Q

INITIAL VENTILATOR SETTINGS

Infant

A
  • Peak Inspiratory Pressure should be set to 15-25 cmH2O
    • PIP Limit should be set to 30
  • Tidal Volume should be set between 3-5 ml/kg
    • What about deadspace
      • Ex. Flow transducers, ETCO2
  • Positive End Expiratory Pressure (PEEP) should be set to 3-6 cmH2O
    • A proper set PEEP is used to prevent further alveolar collapse
    • Increases typically made in increments of 1-2 cmH2O. PEEP may be 8 before alternative modes trialled.
  • Respiratory Rate should be set 20-50
    • Start at 50
    • Used to treat hypercapnia
  • Inspiratory time should be set to 0.3-0.4
    • Start at 0.3
    • Adjust to reach equilibrium
  • Mode
    • Begin with Pressure Control Volume Targeted Ventilation
    • If leak is > 40%
      • Consider a larger ETT, extubation to NIPPVS, or A/C PC ventilation
    • The trend towards using NeoPuff and/or setting up on ventilator sooner. Goal is to minimize inadvertent inverse ratio and high pressures.
21
Q

VENTILATORY CHANGE PARAMETERS

*These goals do not apply when CHD or PPHN is present

VLBW (28-40 Weeks)

A

Goal PaCO2-Emphasize point that regardless of reference it is a permissive hypercapnia strategy overall

  • pH
    • ≥ 7.25
  • PaCO2 (mmHg)
    • 45-55
  • PaO2 (mmHg)
    • 50-70
  • HCO3- mmol/L
    • 18-20
  • SpO2
    • 85-92
22
Q

VENTILATORY CHANGE PARAMETERS

*These goals do not apply when CHD or PPHN is present

ELBW (<28 Weeks)

A

Goal PaCO2-Emphasize point that regardless of reference it is a permissive hypercapnia strategy overall

  • pH
    • ≥ 7.25
  • PaCO2 (mmHg)
    • 45-55
  • PaO2 (mmHg)
    • 45-65
  • HCO3- mmol/L
    • 15-18
  • SpO2
    • 85-92
23
Q

Initial Setting of Peds Vent

Tidal Volume

A

6-8 mL/kg

May be as low as 4mL/kg

May be as high as 10 mL/kg

Will depend upon the size of the pediatric population

For testing I say that goal range of VT is same as adults 6-10 ml/kg normally, 5-7 for protective=this makes whole table similar/same as adults!

Remind that if a small pediatrics (e.g. 10 kg) then think closer to neonatal strategies

24
Q

Initial Setting of Peds Vent

PEEP

A

Start at 4-5 cmH2O

Aim for optimal PEEP

Increase typically made in increments of 1-2 cmH2O

Watch for CV compromise with increasing PEEP

Optimal PEEP is that which achieves the best lung compliance and oxygenation with the fewest CV side effects

25
Q

Initial Setting of Peds Vent

Circuit

A

<25 kg for a neonate

>25 kg Adult

Neo circuit is always heated

Adult circuit will depend upon the size of the pediatric

26
Q

Initial Setting of Peds Vent

Inspiratory Time

A

Smaller child 1.0 seconds

Longer for a larger child

27
Q

Initial Ventilatory Settings for Toddler

A
  • RR (breath/min)
    • 20-35
  • Vt (ml/kg)
    • 5-8
  • Inspiratory Time
    • 0.6-0.7
  • PEEP
    • 5
28
Q

Initial Ventilatory Settings for Small Child

A
  • RR (breath/min)
    • 20-30
  • Vt (ml/kg)
    • 6-9
  • Inspiratory Time
    • 0.7-0.8
  • PEEP
    • 5
29
Q

Initial Ventilatory Settings for Child

A
  • RR (breath/min)
    • 18-25
  • Vt (ml/kg)
    • 7-10
  • Inspiratory Time
    • 0.8-1
  • PEEP
    • 5
30
Q

Initial Ventilatory Settings for Adolescence

A
  • RR (breath/min)
    • 12-20
  • Vt (ml/kg)
    • 7-10
  • Inspiratory Time
    • 1-1.2
  • PEEP
    • 5
31
Q

PEDIATRIC ABG

A
  • pH
    • 7.35-7.45
  • PaCO2(mmHg)
    • 35-45
  • PaO2(mmHg)
    • 80-100
    • *May be less on capillary gas
  • HCO3- (mmol/L)
    • 22-26
  • SpO2
    • 95-100%
    • Goal is just higher than 90%
32
Q

Initial Ventilatory Settings for Adult

Tidal Volume

A

6-10 mL/kg

May be as high as 10ml/kg for patients with neuromuscular and post op patients

Lung protective strategies will be 4-6 ml/kg

33
Q

Initial Ventilatory Settings for Adult

RR

A

12-16

Higher rates run the risk of air trapping

34
Q

Initial Ventilatory Settings for Adult

Inspiratory Time

A

0.8-1.2 seconds

Targeting an I:E of 1:2 or lower

35
Q

Initial Ventilatory Settings for Adult

PEEP

A

Typically start at 5 cmH20

Aim for an optimal PEEP

Increase typically made in increments of 2-3 cmH2O

Watch for CV compromise

Contraindications to PEEP- Increased ICP, untreated pneumothorax, hypotension*

36
Q

Initial Ventilatory Settings for Adult

Minute Ventilation

A

~100 mL/kg to start

80-100ml/kg IBW

Can also use ♂- 4 x BSA

♀-3.5 X BSA

Febrile patient will require a higher MV

Will be adjusted based on PaCO2

37
Q

PEEP and Hemodynamics

A
  • The beneficial effects of PEEP may be outweighed by the effects that PEEP has on hemodynamics.
  • PEEP will result in a reduction in venous return due to the elevated intrathoracic pressure, and by an increased right ventricular afterload that is secondary to the rise of pulmonary vascular resistance.
  • PEEP redistributes cardiac output in favor of brain, heart, adrenals and intestines, whereas the perfusion of stomach, pancreas and thyroid is diminished
  • Reduction of hepatic artery flow, at higher levels of PEEP, may jeopardize liver tissue oxygenation.
  • Under clinical conditions, individual differences regarding pre-existing cardiopulmonary and peripheral-vascular diseases may modify the PEEP-induced hemodynamic alterations in a wide range out of proportion to the fall of cardiac output.
38
Q

Adult ABG

A

pH- 7.35-7.45

PaCO2: 35-45

PaO2: 80-100 (goal 60-100)

HCO3: 22-26

SaO2: 95-100% (Goal >90%)

39
Q

TBI Protocol

A

Head injury-PaO2 80-120 (CHR TBI protocol), PaCO2 on low side normal

40
Q

TIME CONSTANTS

A

Time constants represent how fast pressures equilibrate between the circuit and the alveoli

It represents the maximal rate at which exhalation occurs

Time constant is calculated through multiplying compliance and resistance

The time constant related to inspiratory filling and expiratory emptying of the lungs

Mouth pressure or proximal airway pressure will equilibrate with alveolar pressure in 3-5 time constants (this will be ~0.33 seconds in a newborn and 0.25 seconds in adults)

41
Q

TIME CONSTANTS VALUES

A

1stTime Constant- 63% of the volume is delivered or exhaled

2ndTime Constant- 86.5 % of the volume is delivered or exhaled

3rdTime Constant- 95% of the volume is delivered or exhaled

4th Time Constant- 98.2% of the volume is delivered or exhaled

5th Time Constant- 99.3% of the volume is delivered or exhaled

42
Q

Time Constants and Severe Respiratory Distress

A

In babies with severe respiratory distress and decreased lung compliance one time constant can equal 0.05 seconds

This means that pressure equilibrium occurs in 0.15-0.20 seconds which is the minimum inspiratory time required to ensure complete delivery of tidal volume

43
Q

Time Constants and MAS

A

When airway resistance is high such as in MAS the time constant will become longer meaning we have to use a longer inspiratory time, lower inspiratory flow, and longer exhalation times to ventilate these infants

44
Q

Time Constants and Respiratory System Mechanics

A

Monitoring respiratory system mechanics to derive time constants can assist in properly adjusting adequate inspiratory time and expiratory time during ventilation

The time component is important when using rapid rates to allow for adequate exhalation without developing breath stacking and automatic positive end expiratory pressure (auto PEEP) and to minimize lung damage

45
Q

PRESSURE CONTROL VOLUME REGULATED

A
  • You will set on the ventilator the following parameters
    • Tidal Volume
    • Rate
    • Inspiratory Time
    • PEEP
  • In PRVC rememeber that Pplat and PIP will be the same
46
Q

PRESSURE CONTROL VOLUME REGULATED

AS COMPLIANCE DECREASES

A
  • Because your tidal volume will stay the same you will need to have an increase in PIP and Pplat
    • There will also be an overall increase in Pmean
  • Will change the time constant
  • Your minute ventilation will not change because you control both rate and tidal volume
  • As compliance decreases your Tidyanwill decrease Tistatic will increase and flow will increase
    • The Titotal will not change which means that your Te and I:E will not change
47
Q

PRESSURE CONTROL VOLUME REGULATED

AS RESISTANCE INCREASES

A

Your pressures will remain the same it will be the speed of the flow that will be changing due to the change in the airway diameter Because it is flow is changing it will be the Ti dynamic and Ti static that will change

As resistance increases Tidyn will increase and Tistatic will decrease (Titotal will not change)

Peak flow will be directly proportional to resistance but overall flow will not change (and we can not measure)

48
Q

PRESSURE CONTROL VOLUME REGULATED

AS TI DECREASES

A
  • Your Ti total will decreased and it might be decreased to the extent that we do not reach equilibrium before exhalation starts.
    • Because Ti total is shorter it means that Te is longer. So I:E will decrease
  • As Ti is shorter there will be a higher pressure (PIP) needed in order to deliver the set tidal volume
    • However because of the time that we are delivering that pressure there will be an overall decrease in Pmean
    • Note that there is a larger change in PIP (increase) than there is in Pmean (decrease)
  • In the mode of PRVC if we decrease Ti resulting in a truncation of inspiratory flow what is the affect on peak pressure and the plateu pressure in the lungsPeak pressures will go up but plateau pressures (in the lungs) will not change
    • Ventilator Pplat will go up as it will be the same as PIP in PRVC
49
Q

PRESSURE CONTROL

A

You will set on the ventilator the

PC Absolute/PIP

Rate

Ti

PEEP

50
Q

PRESSURE CONTROL

COMPLIANCE INCREASES

A
  • Tidal volume will increase as we can increase the volume delivered at a certain pressure
    • Because our tidal volume is increasing our minute ventilation will increase as well
  • Ti dyn will increase and Ti pause will decrease
    • Because Ti dyn will increase flow will decrease also your Pmean will increase with an increased Ti dyn
    • You Ti total will not change (so I:E will not change)
51
Q

PRESSURE CONTROL

RESISTANCE INCREASES

A

The only thing that will change is that your Ti dyn will get longer

Remember as resistance increase your flow will decrease making a longer Ti dyn and a short Ti static

52
Q

MANAGING THE VENTILATOR IN INFANTS

A
  • Prevent Hypoxia (SpO2 88-92)
    • Manipulate the FiO2
      • If FiO2 is >0.60 increase the PEEP
    • Manipulate the mean airway pressure
      • Do this through manipulation of Ti (increase in Ti will increase MAP), I:E, or PEEP
  • Prevent Lung Injury
    • Limit FiO2 with PEEP
    • Wean FiO2 if possible
    • Limit Pplat (<30 cmH2O)
  • Prevent Acidosis
    • Increase rate in order to decrease WOB
    • Increase rate to keep pH above 7.25
    • Cause of acidosis
    • Hypoxemia, hypoxemia, hypoxemia
53
Q

WEANIGN INFANTS FROM VENTILATOR

A

Try decreasing rate and watch WOB (SBT)

Wean FiO2 (decrease when SpO2 >93%)

Wean PEEP when FiO2 is below 0.4 – 0.5

We don’t wean aggressively on babies that are losing weight or having huge apneic periods

54
Q

The keys to the management of infants with RDS

A
  • To prevent hypoxemia
    • Allow for normal tissue metabolism
    • Optimize surfactant production
    • Prevent R to L shunting
  • Optimize fluid management
    • Balance between avoiding hypovolemia and shock and on the other side also trying to avoids edema
  • Reduce Metabolic Demands
  • Prevent worsening atelectasis and pulmonary edema
  • Minimize oxidant lung injury
  • Minimize lung injury cause by mechanical ventilation
55
Q

Mechanical Ventilation and CHD

A

Rule out you differential diagnosis before you CHD cause they are very rare

PGE you have to intubate because a side effect of PGE is associated with central apneas

56
Q

Mechanical Ventilation and Non-Cyanotic CHD

A

Minimal ventilator parameters to decrease WOB if needed.

57
Q

Mechanical Ventilation and Cyanotic CHD

A

Minimal ventilator parameters to decrease WOB if needed with minimal FiO2 as SpO2 is not improved and due to the danger of closing the PDA.

58
Q

Mechanical Ventilation and BPD with a PDA

A

Normally a PDA is not a big problem, but when there is a left to right shunt the problem is that this leads to chronic pulmonary edema and it is this edema which is why babies are oxygen dependent

This leads to BPD and when you touch the baby and they cry it will create pressure in their lungs which will increase pressures creating a right to left shunt, which will decrease saturations as the deoxygenated blood being dumped into the aorta and being delivered to the body.

So as a RT you will want to increase FiO2 but you should not touch the FiO2 because as soon as the baby relaxes it will return to being a left to right shunt and we will have an increase in saturations again.

If there is major fluctuations in saturations will be used to determine whether there is a problematic PDA

59
Q

Chronic Lung Disease Pathogenesis

Prematurity-Respirtory Failure Mechanical Ventilation

A
  • Excessive tidal volume and decreased lung compliance
    • Volutrauma
  • Increase inspired oxygen, defifcent antioxidant system, nutritional defiecnies
    • Oxygen toxcicty
  • Pre/postnatal infections, PMN activation
    • inflammatory mediators, elestase/proteinase, inhibitor imbalance
  • PDA, excessive fluid intake
    • increase pulmonary edema and lung edema

All will lead to acute lung injury inflammatory response

60
Q

Acute Lung Injury Inflammatory Response

A
  • Airway Damage
    • Metaplasia, smooth muscle hypertrophy, increase mucus secretiosn
    • Airway obstruction and emphysema atelectasis
  • Vascular Injury
    • Increased permeability, smooth muscle hypertrophy, decreased vascularization
    • Pulmonary edema and hypertension
  • Intersitial Damage
    • Increased fibronectin and elastase, decreased alveolar septation
    • Fibrosis and decreased number of alveoli-capillaries

All lead to Chronic Lung Disease

61
Q

BPD AND OXYGENATION

A

Supplemental oxygen is the main therapy for infants with BPD but the appropriate target remains controversial

Oxygen saturations are accepted at 85-90% after preterm birth

Keep in mind though that patients with severe BPD usually are <36 weeks which is past the time when ROP is a major concern

For BPD, growth failure, respiratory exacerbations and PPHN however we accept saturations of 92-95%

62
Q

BPD VENTILATOR STRATEGIES

EARLY PREVENTION

A
  • Strategies to prevent acute lung injury
    • Low Vt (5-8 ml.kg)
    • Short inspiratory time
    • Increase PEEP at needed lung recruitment without overdistension or reflection at high peak airway pressure
    • Achieve lower FiO2
  • Goals for Gas Exchange
    • Adjust FiO2 to target lower O2 saturations (85-90%)
    • Permissive hypercapnia
63
Q

BPD VENTILATOR STRATEGIES

LATE (EASTABLISHED BPD)

A
  • Marked regional heterogenely
    • Larger Vt (10-12 ml/kg)
    • Longer inspiratory time (>/= 0.6 sec)
  • Airway Obstruction
    • Slower rates allow for better emptying especially with larger Vt
    • Complex roles for PEEP with dynamic airway collapse
  • Interactive effects of vent strategies
    • Changes in RR, Vt, inspiratory and expiratory time, pressure support are highly interdependent
    • Overdistention can increase agitation and paradoxically worsen ventilation
  • Permissive hypercapnia to facilitate settings
64
Q

PDA

A

Right to left shunting

Chronic pulmonary edema

Incidence of greater hypoxemia and possibly metabolic acidosis

If failure to spontaneously close or with drug treatment (indomethacin), may require surgical closure.

Note to clinicians: be wary of increasing FiO2 to compensate as it will not improve SpO2 but may expose patient to toxically high FiO2

65
Q

Reasons to Mechanical Ventilation in Neonates

A
  1. Apnea-Only absolte indication

Acute Ventilatory Failure

Impending Ventilatory Failure

Severe Refractory Hypoxemia

66
Q

Acute Ventilatory Failure in Neonates

A

Type 2 Respiratory Failure (hypercapnic)

pH<7.25 despite use of CPAP and supplemental oxygen of FiO2 >0.60

67
Q

Impending Ventilatory Failure

A

When signs and symptoms of respiratory distress are exhibited, non-invasive CPAP may be trialled prior to intubating and mechanically ventilating (assuming pH > 7.25)

68
Q

Severe Refractory Hypoxemia in Neonates

A

Hypoxemic respiratory failure (PaO2<50 mmHg) despite the use of CPAP and supplemental oxygen (FiO2³0.60)

Associated with:

  • Any kinds of shunt
    • Intrapulmonary shunting
      • Due to MAS, sepsis, pneumonia (not effective opening up the lungs
  • Intracardiac shunting
    • PDA, PFO
69
Q

Congenital Abnormalities that require Ventilation

A
  • Lung hypoplasia
  • CDH
  • Tracheal anomalies
  • Cardiac defects
70
Q

Surfactant and Mechanical Ventilation

A

The need for surfactant require intubation and ventilation

After meconium aspiration

Surfactant deficiency associated with prematurity

The neonate may be intubated to administer surfactant but then, depending on the gestational age and respiratory status, may be extubated to CPAP/SiPAP

71
Q

Signs & Symptoms of Respiratory Distress in the Neonate

A
  • Retractions
    • Intercostal, suprasternal, substernal
  • Grunting
  • Nasal flaring
  • Increasing oxygen requirements
  • Cyanosis
  • Tachypnea
    • RR > 60 bpm
72
Q

Silverman Index

A

Similar to the ones on the adult but more evident in kids

The higher the silverman score the high the distress

Score 10=Severe respirtory distress

Score >/=7 Impending respirtroy failure

Score 0 No respirtory distress

73
Q

Pediatrics Indication for Ventilation

A
  1. Apnea
  2. Acute ventilatory failure- Hypercapnia with a pH < 7.25
  3. Impending ventilatory failure- Clinical signs: Tachypnea, substernal and intercostal retractions, expiratory grunting, nasal flaring, cyanosis, head bobbing
  4. Severe refractory hypoxemia
74
Q

What Influences Mean Airway Pressure

A

PIP

PEEP

I:E Ratio

Flow

75
Q

Why Does PEEP help oxygenation

A

We tend to spend more time in exhalation than inspiration which is why PEEP helps improve oxygenation

76
Q

How will changing from a square waveform to a decelerating waveform influence MAP

A

Decrease MAP

77
Q

Tidal Volume Goals for Adults

A

6-8 ml/kg

May be as high as 10ml/kg for neuromuscular and post op pts.

Lung protective 4-6 ml/kg.

78
Q

RR Goals for Adults

A

12-16 bpm

Higher rate run the risk of air trapping

79
Q

Inspiratory Time Goals for Adults

A

0.8-1.2 s