Trinidad, Buenos Aires, Argentina: 7 a 9 de junio

 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

What is Mode? Volume or Pressure ?? Phase Variables Cycling Pressure Controlled Ventilation Patient Triggered Ventilation

Positive Pressure Ventilation

What is Mode?  Volume or Pressure ??  Phase Variables Cycling  Pressure Controlled Ventilation  Patient Triggered Ventilation

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

 1. Type of breath  2. Control variables  3. Phase variables  4. Conditional variables

 1a. Mandatory breath  1b. Assist breath  1c. Support breath  1d. Spontaneous breath

 2a. Pressure control  2b. Volume control  2c. Dual control mode

PRESSURE = FLOW X RESISTANCE + VOLUME/COMPLIANCE Pressure Flow Volume Compliance = Δ volume Δ pressure Resistance = Δ pressure Δ flow

What is Mode? Volume or Pressure ?? Phase Variables Cycling Pressure Controlled Ventilation Patient Triggered Ventilation

VOLUME PRESETPRESSURE PRESET  Volume Preset ventilators: deliver the same tidal volume of gas each breath, regardless of the inflating pressure that is needed.  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 PRESETPRESSURE PRESET  Volume Preset ventilators : deliver the same tidal volume of gas each breath, regardless of the inflating pressure that is needed.  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 simply means the breaths are pressure constant and volume variable.

 Volume control simply means the breaths are volume constant and pressure variable.

R....B  Coloide  Volume Control  Volutrauma  Pressure triggering  Close Units  Dopamine  Cristaloids  Pressure Control  Barotrauma  Flow Triggering  Open Units  Dobutamine

RIVER PLATEBOCA JUNIORS

ARGENTINABRASIL

 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)

 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.

 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.

 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.

 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.

 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.

 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

VOLUTRAUMABAROTRAUMA  Hillman et al: Briel, large tidal volume ventilation initiates lung injury and a systemic response in fetal sheep AJRCCM 15; 176: , 2007  Moylan et al: The relationship of Bronchopulmonary dysplasia to the occurrence alveolar rupture during positive pressure ventilation. Crit Care Med 6: , 1978

What is Mode? Volume or Pressure ?? Phase Variables Cycling Pressure Controlled Ventilation Patient Triggered Ventilation

 a. Trigger variable  b. Limiting variable  c. Cycling variable  d. Baseline variable

HOW THE VENTILATOR STARTS, SUSTAINS AND ENDS INSPIRATION : 1. TRIGGER: starts the inspiration 2. Limit variable means that does not allowed to rise above a preset value during inspiratory time 3. Cycling Variable: end inspiration 4. Baseline variable Phase Variables

 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 Baseline Trigger Patient effort Pressure -2 cm H 2 O

 FLUXO X PRESSÃO Fluxo 1.0 LPM Pressão Subida da Pressão 25 msec Fluxo Tempo de Resposta do Sistema

Ventilator Disconnected Compare to BASE FLOW 5 Lpm FLOW SEN 1 Lpm Ideal Continuous Flow Flow Triggered Spontaneous Breath Simulated Carina Pressure (cmH 2 0) Tidal Volume (liters)

Ventilator Disconnected Compare to CPAP Mode Sen = 0.5 cmH Ideal Continuous Flow Pressure Triggered Spontaneous Breath Simulated Carina Pressure (cmH 2 0) Volume (l)

Pressure-Supported Breaths Time Pressure cmH 2 0 Net flow Lpm Trigger Interval I 1 = Flow triggered I 2 = Pressure triggered Circuit pressure (flow triggered) Circuit pressure (pressure triggered) Patient inspiring from base flow Pressure trigger point I1I1 I2I2 Onset of effort Flow trigger point

Legend Flow Triggering Pressure Triggering Airway Pressure Patient Effort Baseline Inspiratory Flow Time Returned Flow Delivered Flow Inspiratory Flow Flow Sensitivity Base Flow Time Returned Flow Delivered Flow

Flow Triggering Delivered flowReturned flow No patient effort

Flow Triggering All inspiratory efforts recognized Time Pressure

Flow Triggering Delivered flowLess flow returned

 Limit variable means available variable is not allowed to rise above a preset value during the inspiratory time: Pressure limit Volume limit

 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

Pressão Tempo 25% do pico de fluxo Pico de fluxo Volume Pressão PINSP PEEP Tempo Tempo Fluxo + -

What is Mode? Volume or Pressure ?? Phase Variables Cycling Pressure Controlled Ventilation Patient Triggered 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.

 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.

 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.

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

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

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

What is Mode? Volume or Pressure ?? Phase Variables Cycling Pressure Controlled Ventilation Patient Triggered Ventilation

 A. Intermittent Mandatory Ventilation (IMV)  B. Syncronized Intermittent Mandatory Ventilation (SIMV)  C. Assist/Control Ventilation  D. Pressure Support

- 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.

- 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

Patient and ventilator essentially function independently

- 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.

 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.

 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 SIMV

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.

 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 Neil MacIntyre: Respiratory function during pressure support ventilation. Chest 1986

-Pressure support is a patient-triggered, pressure- limited, 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

 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.

PtrPtr Flow o Volume P es PEEP Peak flow 25% do pico de Fluxo Inspiratory Time Tempo

PSV F P

Pressure Support Ventilation 10 cm Time Pressure Pressure Support

 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.

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 Kanak et al: Oxygen cost of breathing. Chest 1985

 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

Trinidad, Buenos Aires, Argentina: 7 a 9 de junio