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MODALIDADES BÁSICAS DE VENTILACIÓN MECÁNICA
MODALIDADES BÁSICAS DE VENTILACIÓN MECÁNICA.

We need to have two primary goals in mind:
(1) to ease the work of breathing in the
critically ill neonate
(2) to reduce the incidence of neonatal
lung injury, or bronchopulmonary dysplasia
(BPD)
Eichenwald & Stark, NEJM 2008
MODALIDADES BÁSICAS DE VENTILACIÓN MECÁNICA
What is Mode?
Volume or Pressure ??
Phase Variables Cycling
Pressure Controlled Ventilation
Patient Triggered Ventilation
Positive Pressure Ventilation
MODALIDADES BÁSICAS DE VENTILACIÓN MECÁNICA
What is Mode?




Volume or Pressure ??
Phase Variables Cycling
Pressure Controlled Ventilation
Patient Triggered Ventilation
WHAT IS MODE?
Mode of ventilation is the method or way ,in
which a breath is delivered by altering or
changing the available variables.
A Mode is nothing but how a ventilator
performs the work of respiratory muscles
COMPONENTS OF A MODE
1. Type of breath
 2. Control variables
 3. Phase variables
 4. Conditional variables

1. TYPE OF BREATH
1a. Mandatory breath
 1b. Assist breath
 1c. Support breath
 1d. Spontaneous breath

2. CONTROL VARIABLES
2a. Pressure control
 2b. Volume control
 2c. Dual control mode

PRESSURE = FLOW X RESISTANCE + VOLUME/COMPLIANCE
Flow
Resistance = Δ pressure
Δ flow
Pressure
Volume
Compliance = Δ volume
Δ pressure
MODALIDADES BÁSICAS DE VENTILACIÓN MECÁNICA
What is Mode?
Volume or Pressure ??
Phase Variables Cycling
Pressure Controlled Ventilation
Patient Triggered Ventilation
VOLUME PRESET

Volume Preset ventilators:
deliver the same tidal
volume of gas each breath,
regardless of the inflating
pressure that is needed.
PRESSURE PRESET

Pressure-preset ventilators,:
in contrast, are designed to
deliver a volume of gas with
each breath until a preset
limiting pressure designated
by the physician is reached.
VOLUME PRESET

Volume Preset ventilators :
deliver the same tidal
volume of gas each breath,
regardless of the inflating
pressure that is needed.
PRESSURE PRESET

Pressure-preset ventilators,:
The remainder of volume in the
unit is then released into the
atmosphere. As a result, the
tidal volume that is delivered to
the patient by pressure-preset
ventilators with each breath
may be variable, but the peak
pressure delivered to the airway
remains constant
PRESSURE CONTROL

Pressure control simply means the breaths are
pressure constant and volume variable.
VOLUME CONTROL

Volume control simply means the breaths are
volume constant and pressure variable.
R....
B......

Coloide

Cristaloids

Volume Control

Pressure Control

Volutrauma

Barotrauma

Pressure triggering

Flow Triggering

Close Units

Open Units

Dopamine

Dobutamine
DILEMAS ETERNOS
RIVER PLATE
BOCA JUNIORS
BOCA JUNIORS O RIVER PLATE
ARGENTINA
BRASIL
ARGENTINA O BRASIL
DUAL CONTROL MODE

Dual control mode are newer modes which are
capable of switching from one to another , e.g.,
pressure regulated colume control (PRVC), Auto
mode, Adaptative pressure ventilation (APV)
BE AWARE

Termination of inspiration is now recognized to
be an important component of ventilator
control, because prolongation and plateau
formation during inspiration , especially with
pressure limited modes, may lead to air
trapping air leak, and chronic lung injury.
VOLUME GUARANTEE VENTILATION (VGV)

The Volume Guarantee Ventilation was
introduced to more tightly regulate the volume
delivery to the lung ( Babylog 8000)

In VGV, the operator chooses a target tidal
volume and selects a pressure limit up to which
the inspiratory pressure may be adjusted.
VOLUME GUARANTEE VENTILATION (VGV)

The microprocessor of the unit then compares
exhaled tidal volume of the prior breath to the
desired target and readjust the inspiratory
pressure up or down to deliver the targeted
tidal volume.
VOLUME GUARANTEE VENTILATION (VGV)

Exhaled tidal volume is used in this mode for
the regulation of the inspiratory pressure
because it more closely approximates the tidal
volume in the neonate who has a leak around
an uncuffed endotracheal tube.
VOLUTRAUMA

The newer modalities of ventilatory support are
byproducts of the modern computer era and
have been made possible by the use of
microprocessors that permit very small
beneficial modifications to pressure, flow and
volume throughout the ventilatory cycle.
VOLUTRAUMA

The primary rationale behind these novel
approaches is that the volume delivered to the
lung, or volutrauma, may be of greater
importance in the lung injury than the pressure
injury or barotrauma.
McCallion et al : Volume targeted versus
pressure limited ventilation in NB ,
Cochrane Database Syst Rev
VOLUTRAUMA

Hillman et al:
Briel, large tidal volume
ventilation initiates lung
injury and a systemic
response in fetal sheep
AJRCCM 15; 176: 575-581,
2007
BAROTRAUMA

Moylan et al:
The relationship of
Bronchopulmonary dysplasia
to the occurrence alveolar
rupture during positive
pressure ventilation.
Crit Care Med 6: 140-142,
1978
VOLUTRAUMA VS BAROTRAUMA
MODALIDADES BÁSICAS DE VENTILACIÓN MECÁNICA
What is Mode?
Volume or Pressure ??
Phase Variables Cycling
Pressure Controlled Ventilation
Patient Triggered Ventilation
PHASE VARIABLES
a. Trigger variable
 b. Limiting variable
 c. Cycling variable
 d. Baseline variable

HOW THE VENTILATOR STARTS, SUSTAINS AND ENDS
INSPIRATION
Phase Variables
2
:
3
1.
2.
3.
1
4
4.
TRIGGER: starts the
inspiration
Limit variable means that
does not allowed to rise
above a preset value during
inspiratory time
Cycling Variable: end
inspiration
Baseline variable
A. TRIGGER VARIABLE

Trigger variable – What starts inspiration
a) Machine trigger or time trigger when the
ventilator starts a breath according to a set
frequency
b) Patient trigger: pressure or flow.
When the ventilator senses a drop in baseline
pressure or flow when caused by the patient’s
inspiratory effort
Pressure Triggering
Patient effort
Pressure
Baseline
Trigger
-2 cm H2O
DISPARO

FLUXO X PRESSÃO
Fluxo
1.0 LPM
Pressão
Subida
da
Pressão
25 msec
Fluxo
Tempo de Resposta do Sistema
Tidal Volume
(liters)
1.0
Ventilator Disconnected
Compare to
BASE FLOW 5 Lpm
FLOW SEN 1 Lpm
0.9
0.8
Ideal Continuous
Flow
0.7
0.6
0.5
0.4
0.3
0.2
Flow Triggered
Spontaneous
Breath
0.1
0
-20
-15
-10
-5
0
5
10
15
Simulated Carina Pressure (cmH20)
20
Volume (l)
1.0
Ventilator Disconnected
Compare to CPAP Mode
Sen = 0.5 cmH2 0
0.9
0.8
0.7
Ideal Continuous
Flow
0.6
0.5
0.4
0.3
0.2
Pressure Triggered
Spontaneous Breath
0.1
0
-20
-15
-10
-5
0
5
10
Simulated Carina Pressure (cmH20)
15
20
TRIGGER FLUXO X PRESSÃO
Pressure-Supported Breaths
Pressure cmH20
Circuit pressure
(flow triggered)
I1
Net flow Lpm
Onset of
effort
Flow
trigger
point
Circuit pressure
(pressure triggered)
I2
Pressure trigger point
Time
Patient inspiring from
base flow
Trigger Interval
I1 = Flow triggered
I2 = Pressure triggered
Delivered Flow
Returned Flow
Base Flow
Flow Sensitivity
Time
Airway Pressure
Patient
Effort
Returned
Flow
Delivered
Flow
Flow Triggering
Pressure Triggering
Baseline
Inspiratory
Flow
Inspiratory Flow
Time
Legend
Flow Triggering
Returned flow
No patient effort
Delivered flow
Flow Triggering
All inspiratory efforts recognized
Pressure
Time
Flow Triggering
Less flow returned
Delivered flow
LIMITING VARIABLE

Limit variable means available variable is not
allowed to rise above a preset value during the
inspiratory time:
Pressure limit
Volume limit
CYCLING VARIABLE

The variable that is measured and used to end
inspiration is called cycle variable:
Time cycled – cycling is due to set inspiratory
time
Volume cycled
Flow cycled
CYCLING VARIABLE – WHAT ENDS INSPIRATION
Fluxo
+
25% do pico
de fluxo
-
PINSP
Pressão
Pico de
fluxo
PEEP
Tempo
Pressão
20
10
0
Volume
Tempo
Tempo
MODALIDADES BÁSICAS DE VENTILACIÓN MECÁNICA
What is Mode?
Volume or Pressure ??
Phase Variables Cycling
Pressure Controlled Ventilation
Patient Triggered Ventilation
CONTROLLED MANDATORY VENTILATION

CMV / Assist mandatory ventilation are full
support modes.

Full support modes are required in acutely ill
patients who require guaranteed and often
high minute ventilation .
CONTROLLED MANDATORY VENTILATION

These modes perform most or all of the work of
respiratory muscles, necessary to maintain
adequate minute ventilation.

Because of full support , these modes also
reduce the oxygen and energy consumed by the
respiratory muscles.
PRECAUTIONS WITH CMV
These patients can neither trigger breath nor
inspire air through the ventilatory circuit.
 The patient’s respiratory effort should be
suppressed by sedative, intentional
hyperventilation or muscle relaxants.

INDICATIONS OF CMV
1. To provide maximum ventilatory support to a
patient with marginal cardiorespiratory
reserve
2. Controlling minute ventilation for reducing in
cerebral blood volume and intracranial
pressure are urgent priorities
3. Reducing oxygen consumption in patients with
respiratory fatigue with poor cardiac output
INDICATIONS OF CMV
4. Ventilatory total control facilitates the
therapeutic application of nonphysiologic
breathing patterns ( Permissive hypercapnia)
5. To reduce agitation in the patient fighting the
ventilator
6. Helps to heal the injured chest wall
7. Status Epilepticus
COMPLICATIONS OF CMV
Since the patient’s spontaneous respiratory drive
will have been blunted with sedation/paralysis
in the control mode, the patient is totally
dependet on the ventilator for ventilation and
oxygenation:
1. Hypoxia during accidental disconnection;
2. Respiratory alkalosis
3. Respiratory muscle atrophy
FISIOLOGÍA Y MODALIDADES BÁSICAS DE
VENTILACIÓN MECÁNICA
What is Mode?
Volume or Pressure ??
Phase Variables Cycling
Pressure Controlled Ventilation
Patient Triggered Ventilation
PATIENT TRIGGERED VENTILATION
A. Intermittent Mandatory Ventilation (IMV)
 B. Syncronized Intermittent Mandatory
Ventilation (SIMV)
 C. Assist/Control Ventilation
 D. Pressure Support

ASYNCHRONOUS BREATHING MAY RESULT IN SEVERAL
DELETERIOS EFFECTS
- Efficiency of gas exchange may be impaired
- Contributes to air trapping and pneumothorax
- Tremendous variability and irregularity of both
arterial blood pressure waveforms and cerebral
blood velocity, which were associated with a
high incidence of intraventricular hemorrhage.
MEANS TO DEAL WITH ASYNCHRONY:
- Reduce PaCO2 by increasing the ventilator
parameter
- Pharmacologic agents: analgesics, sedatives,
pharmacologic paralysis
- It was finally shown that asynchrony could be
correctable if the patient’s spontaneous effort and the
onset of mechanical inspiration could be coordinated
SPONTANEOUS PATIENT BREATHS AND MECHANICAL
VENTILATOR BREATH
Patient and ventilator
essentially function
independently
A. INTERMITTENT MANDATORY VENTILATION (IMV)
- When synchrony occurs, it is merely a random event.
- Even if the infant initiates a breath simultaneously
with mechanical inspiration, differing inspiratory times
may result in the development of asynchrony during
the expiratory phase.
- For some breaths, the infant may be attempting to
exhale against the full pressure of a mechanical
inspiration.
The onset of mechanical
inspiration is
synchronized to the onset
of patient inspiration;
--The
patient breathes
spontaneously between
mechanical breaths.
--Note
that dyssynchrony
can develop during the
expiratory phase because
the inspiratory times of
the patient and ventilator
differ.
B. SYNCRONIZED INTERMITTENT MANDATORY
VENTILATION (SIMV)
SIMV


In SIMV, the mechanically delivered breaths are
synchronized to the onset of spontaneous patient
breaths.
During SIMV, the patient may breathe spontaneously
between mechanical breaths from the continuous
bias flow in the ventilatory circuit, but these breaths
are supported only by PEEP.
SIMV

Each mechanical breath is initiated in response to the
onset of the patient's own respiratory effort; this
results in inspiratory synchrony.

However, unless the inspiratory times are identical,
the patient may terminate his or her own effort and
begin exhalation while the ventilator is still in the
inspiratory phase. This again results in partial
asynchrony.
IMV
THE DIFFERENCE OF IMV & SIMV
SIMV
ASSISTED CONTROLLED VENTILATION
ACV
This mode involves either the delivery of a
synchronized mechanical breath each time a
spontaneous patient breath meeting threshold
criteria is detected (assist) or the delivery of a
mechanical breath at a regular rate in the event that
the patient fails to exhibit spontaneous effort
(control).
Each spontaneous
breath that meets
threshold criteria
results in the delivery
of a nearly
simultaneous
mechanical breath;
however, expiratory
asynchrony occurs
when inspiratory
times for the patient
and ventilator are not
identical.
ASSIST / CONTROL VENTILATION
Neil MacIntyre: Respiratory function during
pressure support ventilation . Chest 1986
PRESSURE SUPPORT VENTILATION



The difference between volume ventilation in the late
1960s and the 1990s is remarkable.
The development of microprocessor technology and
the availability of accurate flow and pressure
transducers have made significant improvements in
ventilator design and performance.
In conjunction with engineering developments,
enhancements in ventilator modalities included SIMV
and pressure-support ventilation (PSV), which was
first introduced in 1981
PRESSURE SUPPORT VENTILATION
-Pressure support is a patient-triggered, pressurelimited, flow-cycled mode of ventilation designed to
assist a patient's spontaneous effort with an inspiratory
pressure “boost.”
- Pressure support can be used in conjunction with
other modes, such as SIMV, or it can be applied
independently.
- Pressure support is generally applied during weaning
to reduce the imposed work of breathing created by
high-resistance endotracheal tubes, the ventilator
circuit, and the demand valve in demand systems
PRESSURE SUPPORT VENTILATION

Once the breath is triggered, flow is delivered
to the patient airway and pressure rises rather
quickly to the selected pressure-support
setting. The patient's effort is the primary
determinant of the amount of flow delivery that
affects the rise in pressure.
Ptr
PEEP
+
Pes
+
Flow
o
Peak
flow
25% do
pico de
Fluxo
Inspiratory Time
Volume
Tempo
PRESSURE SUPPORT
PRESSURE SUPPORT
PSV
P
F
Pressure Support Ventilation
10 cm
Pressure
Pressure Support
Time
PRESSURE SUPPORT: CLINICAL EXPERIENCE

Pressure support is attracting increased
attention, not only as an alternative weaning
mode but also as a primary modality in the
treatment of patients with acute and chronic
ventilatory failure.
Kanak et al: Oxygen cost of breathing.
Chest 1985
PRESSURE SUPPORT : CLINICAL EXPERIENCE
In 1985, Kanak et al reported improved mixed
venous blood oxygen saturation and decreased
oxygen consumption in patients receiving SIMV
with pressure support compared with those
receiving only SIMV
SI HIPOCRATES FUERA INTENSIVISTA PEDIÁTRICO SU PRIMUM NON NOCERE PARA
VENTILACIÓN MECANICA EN NEONATOLOGIA SERIA:

We need to never forget these two primary
goals in mind:
(1) to ease the work of breathing in the
critically ill neonate
(2) to reduce the incidence of neonatal
lung injury, or bronchopulmonary dysplasia
(BPD)
Eichenwald & Stark, NEJM 2008
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