170 likes | 364 Views
Mechanical Ventilation in the Neonate. RC 290. CPAP. Indications: Refractory Hypoxemia PaO2 < 50 on an FIO2 of 60% or > Many hospitals use 50% as the upper limit before changing to CPAP Transitional therapy between simple O2 therapy and mechanical ventilation
E N D
CPAP Indications: • Refractory Hypoxemia • PaO2 < 50 on an FIO2 of 60% or > • 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:AdministrationTechniques • 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 10-12 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 < with a PaCO2 of 55 mmhg 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
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: 10-30 (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): 4-10 LPM Depends on ventilator and size of infant Time Cycled IMV:Initial Settings
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: 35-55 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 10-20 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!