Mechanical Ventilation in the Neonate RC 290

CPAP Indications: Refractory Hypoxemia –PaO2 –Many hospitals use 50% as the upper limit before changing to CPAP Transitional therapy between simple O2 therapy and mechanical ventilation –Usually in the early stages of a disease or when recovery starts Any disease that causes increased elastic resistance and alveolar instability

CPAP: EFFECTS Increased FRC, ie, back towards normal Decreased shunt Adequate PaO2 at minimal FIO2 W.O.B. ? –By increasing FRC, CPAP should decrease the W.O.B. –However, it requires active exhalation which increases W.O.B. To go on CPAP an infant needs to be breathing spontaneously and to have normal (or slightly lowered) PaCO2

CPAP: Administration Techniques Mostly flow resistors –To change CPAP level, change either flow rate or the amount of resistance May be administered via mask, nasal cannula, hood, or ET tube –An orogastric tube may be needed if using a mask, cannula, or hood

CPAP: Hazards Hemodynamic compromise Pulmonary Baro/Volutrauma Gastric insufflation

CPAP: Management Technique Start at current FIO2 or slightly > Start at 4-5 cmH2O Titrate level in 1-2 cmH2O increments until PaO2 is acceptable –Watch pulse oximeter or TCM as well –Maximal level is usually cmH2O Weaning: Get FIO2 to 50% or < Decrease CPAP in 1-2 cmH2O increments –Monitor for stability in vital signs, ABGs, and pulse oximeter If on ET tube, extubate when CPAP is 2 cmH2O

Mechanical Ventilation: Indications Any acute or chronic cardiopulmonary insufficiency –May be due to problem with lung, cardiovascular system, CNS, or various metabolic disorders Clinical signs: ARF: pH = 7.25 or Repeated A-B spells FIO2 requirement of 50% or > –Some hospitals may use 60% or >

Mechanical Ventilation: Hazards Problems associated with increased mean ITP –Hemodynamic compromise, pulmonary baro/volutrauma Mechanical failure –Usually human failure! BPD, ie, Bronchopulmonary Dysplasia

Mechanical Ventilation: Modes All modes are available to the neonate Time cycled IMV (with pressure limiting) –Newer neonatal vents may allow volume cycled IMV Newer neonatal ventilators can do A/C volume cycle or pressure control

Time Cycled IMV: Initial Settings FIO2: Current FIO2 or slightly > PEEP: minimum of 2 cmH2O (because of ET tube) –Usual range is 2 – 7 cmH20 but may go higher Rate: (depends on PaCO2 prior to CMV) Inspiratory time (IT):.15 to 1.5 seconds –Usually.5 to.6 seconds for starters –Maintain adequate Vt and I:E ratio Peak Pressure (PIP): 10 to 20 cmH2O –Assess breath sounds and chest expansion Flowrate (Peak Flow): LPM –Depends on ventilator and size of infant

Target Values: MAP Mean Airway Pressure Average pressure exerted on the airways from the start of one inspiration until the next Is affected by IT, PIP, Rate, and PEEP Baro/Volutrauma seen with values above 12 cmH2O It is the most powerful influence on oxygenation!

Target Values: ABGs pH: 7.25 – 7.45 PaCO2: mmhg –Increased chances of intracranial bleed if above 55 mmhg PaO2: 50 – 70 mmhg –Capillary is 35 – 50 mmhg

Adjusting Ventilator Parameters To change PaCO2 ONLY, change rate –To increase PaCO2 only, decrease rate –To decrease PaCO2 only, increase rate To Change PaO2 ONLY, change FIO2, PEEP, or IT –FIO2 is changed in 1- 5 % increments –PEEP is changed in 1 – 2 cmH2O increments To change both PaCO2 and PaO2 at the same time, but in opposite directions, change PIP –Increase PIP, PaO2 increases, PaCO2 decreases –Decrease PIP, PaO2 decreases, PaCO2 increases

Increased I time and Inverse IE Ratios Used when increasing FIO2 and PEEP is NOT raising PaO2 Used for increased elastic resistance with short time constant –RDS, atelectasis, bilateral pneumonia Rate should be no greater than 30 and PIP should be no greater than 30 cmH2O

Weaning Decrease FIO2 and PEEP (as already described for CPAP) When rate is down to 10-12, try CPAP Decrease PIP to cmH2O When stable on CPAP of 2 cmH2O and FIO2 of 40% or less, extubate Start weaning with the parameter that is most extreme Monitor for stability of vital signs, TCM values, and pulse oximeter values at all times

Ventilator care requires a team effort. Everyone involved has to get along and trust one another!