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.
Basics of Mechanical Ventilation in Neonates
Everyone involved has to get along
and trust one another!
◘ 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).
◘ (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 .
= 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
◘ one time constant → 63% equilibration of pressure inside & outside the alveoli.
◘ we need 3 time constant →97% equilibration of pressure inside & outside the alveoli.
continuous-flow ventilators Ventilators
–Reduces gradient between PIP & PEEP→ (↓ VT) .
–Decreases venous return .
–Increases pulmonary air leaks .
–Produces CO2 retention .
Minute alveolar ventilation
= (Tidal volume – Dead space) X Frequency.
Ti and Te
●(Ti)is .3 - . 5 seconds for LBW
and .5 - .6 seconds for larger infants
●Depends on the pulmonary mechanics:
– Compliance .
– Resistance .
● It should NOT be reversed
● I:E ratio should NOT be less than 1:1.2
Flow rates of 6-10 liter/min are usually sufficient.
Who is theCommander?
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.
B) Patient–Triggered Ventilators (PTV)
Blood Gases Changesby Ventilator Setting