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Dr.Wahid Helmy pediatric consultant. Basics of Mechanical Ventilation in Neonates. Ventilator care requires a team effort. Everyone involved has to get along and trust one another !. Prevention of alveolar collapse.

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Dr wahid helmy pediatric consultant

Dr.Wahid Helmypediatric consultant.

Basics of Mechanical Ventilation in Neonates


Dr wahid helmy pediatric consultant

Ventilator care requires a team effort.

Everyone involved has to get along

and trust one another!


Dr wahid helmy pediatric consultant

Prevention of alveolar collapse

◘ Functional residual capacty (FRC).

◘ Surfactant .

◘Elatic-recoil ( compliance).

◘ Intrapleural pressure(-4mmHg) during inspiration and (+4mmHg) during inspiration .

◘ If surfactant is absent , Intrapleural pressure negativity may be increased up to (-20mmHg).


What is it

What is it?


Dr wahid helmy pediatric consultant

Pulmonary Mechanics


Dr wahid helmy pediatric consultant

1)Tidal Volume (Vt)

◘ (Vt) = 6-10 mL/kg/Breath.

◘RR is usually 30-60 BPM.

2) minute volume

= (Vt- Dead space)x RR.

↑ (PIP)→↑Tidal Volume →↑minute volume .


Dr wahid helmy pediatric consultant

3) Compliance = 0.004 L/cmH2O.

= Change in volume (mL) = 0.004 L/cmH2O.

Change in pressure(cmH2O)

4)Resistance = 30cm H2O/L/sec

Change in pressure (cmH2O)= 30cm H2O/L/sec

Change in flow (L/sec)

NB., Resistance X Compliance = 1Time constant

1Time constant =0.004 L/cmH2O. X 30cm H2O/L/sec =12


Dr wahid helmy pediatric consultant

4)one Time constant = Resistance X Compliance

◘ one time constant → 63% equilibration of pressure inside & outside the alveoli.

◘ we need 3 time constant →97% equilibration of pressure inside & outside the alveoli.

  • If resistance =30cm H2O/L/sec

  • compliance = 0.004 L/cmH2O.

  • One time constant =30 X 0.004 = 0.12 seconds.

  • We need 3time constant to inflate and deflate the lung (3 X 0.12 seconds = 0.36 seconds=Ti ).

  • as aresult Te= 2 or 3 X 0.36seconds.

  • So I/E ratio = 1:2 or 1:3 .


Dr wahid helmy pediatric consultant

Types of Mechanical Ventilators


Dr wahid helmy pediatric consultant

Types of Mechanical Ventilators

  • Volumev- cycled ventilators.لمجرد المعرفة

  • Pressure ventilators . لمجرد المعرفة

  • Pressure-limited, time-cycled, continuous-flow ventilators .هام جدا

  • Patient–triggered ventilators (PTV).هام جدا


Dr wahid helmy pediatric consultant

What is it?


Dr wahid helmy pediatric consultant

Pressure-limited, time-cycled,

continuous-flow ventilators Ventilators

  • You select (PIP)→ (pressure-limited).

  • You select inspiratory time → (time-cycled).

  • (Continuous flow) →Fresh heated humidified gas is delivered to the patient throughout the respiratory cycle.


Dr wahid helmy pediatric consultant

Parameters of mechanical ventilation


Dr wahid helmy pediatric consultant

(PIP) minus(PEEP)

  • (PIP) → The maximum pressure reached during inspiration. If PIP is too low → low VT. If PIP too high → high VT → Hyperinflation and air leak → Impedance مقاومةof venous return.

  • (Optimum (PEEP) is 4-6 cmH2O).

  • High PEEP >8 cmH2O .,→

–Reduces gradient between PIP & PEEP→ (↓ VT) .

–Decreases venous return .

–Increases pulmonary air leaks .

–Produces CO2 retention .


Dr wahid helmy pediatric consultant

(FiO2)

  • why Increase in FiO2 improves oxygenation ? ↑ oxygen tension inside the alveoli→ ↑ r diffusion gradient → good oxygenation.

  • Why Oxygen and Paw balance is essentiaL ? to minimize lung damage.

  • Why Paw should be ↓ before a very low FiO2 is reached During weaning. to avoid a high incidence of air leak is observed.


Dr wahid helmy pediatric consultant

RR, secrets

  • ↑ RR → ↑ (CO2 wash).

  • RR(60 BPM) allows for PIP reduction in PIP → ↓ incidence of pneumothorax with about 50% .

  • Most neonates have short time constants so they can tolerate (RR60-70 Bpm) and short (Te) without marked gas trapping .

  • RR Determinesيحدد minute ventilation(RR×VT),thusCO2 elimination.


Dr wahid helmy pediatric consultant

Minute alveolar ventilation

Minute alveolar ventilation

= (Tidal volume – Dead space) X Frequency.

  • Tidal volume,is determined mainly with pressure gradient between inspiration and expiration i.e. (PIP) minus (PEEP).


Dr wahid helmy pediatric consultant

Ti and Te

●(Ti)is .3 - . 5 seconds for LBW

and .5 - .6 seconds for larger infants

●Depends on the pulmonary mechanics:

– Compliance .

– Resistance .

–Time constant.

I:E ratio

● It should NOT be reversed

● I:E ratio should NOT be less than 1:1.2


Dr wahid helmy pediatric consultant

mean airway pressure

  • MAP + FiO2 → determines oxygenation.why?

  • An ↑ in PIP and PEEP→ ↑ MAP → ↑ oxygenation more than ↑ in the I:E ratio.

  • NB., ↑↑↑ Paw →alveolar over distension with right to left shunt.

Flow

Flow rates of 6-10 liter/min are usually sufficient.


Dr wahid helmy pediatric consultant

Modes of venilation

Who is theCommander?


Dr wahid helmy pediatric consultant

A)Non-triggeredModes.

1.Controlled Mandatory Ventilation (CMV) or IPPV:

– IPPV (intermittent positive pressure ventilation ).

–Ventilator rate is set > infant's spontaneous.

– RR (usually 50-80 breaths/min).

2.Intermittent Mandatory Ventilation (IMV):

–Ventilator rate is set < infant's spontaneous breaths.

– RR (<30 breaths/min).

– spontaneous breaths above the set rate are not assisted.


Dr wahid helmy pediatric consultant

B) Patient–Triggered Ventilators (PTV)

  • Modification of conventional ventilation ( IMV or IPPV) by adding synchorinization (S).

  • ASensor detect the Inspiratory efforts of the baby by so triggering ( the ventilator setting.

  • the patient is able to initiate (trigger) ventilator breaths.


Dr wahid helmy pediatric consultant

PTV is used in two modes

  • Assist Control Mode (A/C) or sippv

    • All breath initiated by patient is triggered= Assist.

    • Back up rate = ippv = ControL MV.

    • If apnea occur at any time baby will be ventilated.

  • Synchronized Intermttent Mandatory Ventilation (SIMV):

    • Preset rate that is triggered,

    • other patient breath is not assisted.


Dr wahid helmy pediatric consultant

Indications of Mechanical Ventilation

  • hypoxemia→ with PaO2 less than 50 mmHg despite FiO2 of 0.8.

  • Respiratory acidosis → pH of less than 7.20 to 7.25, or PaCO2 above 60 mmHg.

  • Severe prolonged apnea.

  • Frequent intermittent apnea unresponsive to drug therapy.

  • Relieving work of breathing in an infant with signs of respiratory difficulty.


Dr wahid helmy pediatric consultant

Blood Gases Changesby Ventilator Setting


Dr wahid helmy pediatric consultant

ET Size


Dr wahid helmy pediatric consultant

Initial Setting of Mechanical Ventilation


Dr wahid helmy pediatric consultant

Monitoring The Infant during Mechanical Ventilation

  • (ABG)) .,

    • Obtain a blood gas within 15-30 minutes of any change in ventilator settings.

    • Obtain a blood gas every 6 hours unless a sudden change in the infant's condition occurs.

    • Continuous monitoring of the O2 saturation level as well as the HR and RR is necessary.


Dr wahid helmy pediatric consultant

Paralysis and Sedation

  • It is not routinely indicated.

  • It may be used in irritable infants with their spontaneous respiration is out of phase with the ventilator( as in modes with preset rates as in ippv and imv) .

  • in infants with RDS→ ↓dynamic lung compliance →↑ airway resistance, the removal of the infant’s respiratory effort contribution to tidal breathing.

  • after initiation of neuromuscular blockadeit is necessary to increase ventilator pressure


Dr wahid helmy pediatric consultant

Weaning

  • Parameters gradually decreased (PIP 2 cm H2O, FiO2 5%, Rate 5 BPM).

  • 1.Reduce FiO2 to 80% before changing PIP, I:E or PEEP.

  • 2.Reduce PIP as clinically indicated.

  • 3.Reduce FiO2 to less than 60%

  • 4.Reduce inspiratory time.

  • 5.Reduce PIP to 10-14 cm H2O (Larger babies may be extubated with PIP 14-18)

  • 6.Reduce rate to 20 -40 /BPM then Te should be prolonged.


Dr wahid helmy pediatric consultant

Weaning (cont.)

  • 7.preterm infants → Use of nasal CPAP → to avoid atelectasis.

  • 8.prolonged intubation or previous failure of extubation → a short course of steroids may facilitate extubation.

  • 9.If stridor caused by laryngeal edema develops after extubation, →nebulization with adrenaline.


Dr wahid helmy pediatric consultant

THANK YOU


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