1. BY: NICOLE STEVENS

2.  Primary objective of mechanical ventilation is to support breathing until neonates own respiratory efforts are sufficient  First record of mechanical ventilation for a neonate was in 1959  It has been one of the most important breakthroughs in the history of neonatal care  Mortality from respiratory disorders has decreased markedly after the introduction of mechanical ventilation  But it created an increase in a new morbidity (chronic lung disease, or, broncho pulmonary dysplasia)

3.  Neonates are intubated because of 2 main reasons: hypercapnic respiratory failure or hypoxemia.  Hypercapnic respiratory failure is an inability to remove CO2 by spontaneous breathing; it is caused by hypoventilation or severe V/Q mismatch; it causes an increase in arterial PCO2 and a decrease in pH.  Hypoxemia is usually the result of V/Q mismatch or a R) to L) shunt; or diffusion abnormalities (abnormal space between alveolus and capillaries) and hypoventilation (apnoea)

4.  Respiratory failure can occur because of diseases in the lung, thorax, airway or respiratory muscle  Indications for assisted ventilation: 1. Respiratory acidosis (pH < 7.2, CO2 elevated, normal is 35 - 45) 2. Hypoxemia while on 100% O2 3. Or on CPAP (8cm H20) with increasing oxygen requirements (above 40 – 60%) 4. Severe apnoea

5. Clinical manifestations:  Increase or decrease in respiratory rate  Increase or decrease in respiratory effort  Periodic breathing with increase in respiratory effort  Apnoea

6.  Manual ventilation (eg. Neopuff)  Pressure controlled ventilation  Volume controlled ventilation  High freqency oscillation ventilation  High frequency jet ventilation

7. PIP (peak inspiratory pressure)  Changes affect PaO2 & PaCO2 by altering the MAP (mean airway pressure)  Increase in PIP: increases PaO2 & decreases PaCO2  A high PIP should be used cautiously because it may cause volutrauma, which can lead to air leak and BPD  The bigger the baby does not necessarily mean a higher PIP requirement; requirement is determined by lung compliance

8. PEEP (positive end expiratory pressure)  Adequate PEEP prevents alveolar collapse and maintains lung volume at the end of expiration (maintains FRC)  Improves V/Q matching  Very high PEEP can cause overdistention which puts pressure on the heart, reduces venous return, then cardiac output, decreases O2 transport and increases pulmonary vascular resistance

9. Rate/frequency of ventilation  Change in rate alters alveolar minute ventilation  High rate, low tidal volume is preferred  Increase in rate can increase CO2 clearance  Decrease in rate can decrease CO2 clearance

10. Inspiratory:Expiratory ratio  Increase in the I:E ratio leads to an increase in MAP  A long inspiratory time: can increase oxygenation, and may improve gas distribution; but, may cause gas trapping, increased risk of volutrauma and air leak, impaired venous return and increase PVR.  Neonates generally have a very short inspiratory time eg 0.2 – 0.3 secs for a prem and slighter more for a term infant; spend approx. 1/3 time in inspiration and 2/3 in expiration

11. FiO2  Changes alter alveolar oxygen pressure Flow  Minimal effects  In general 8 – 12 litres used  Higher flows needed to achieve shorter inspiratory times

12.  Depends largely on the FiO2  Oxygenation increased with increase in MAP  MAP is a measure of the average pressure to which the lungs are exposed  In CPAP for example: by increasing the PEEP you can achieve an increase in oxygenation

13.  SIPPV (synchonised intermittent positive pressure ventilation), sychronises and supports all breaths made by the baby, if baby not breathing spontaneously will deliver breaths at the rate set.  SIMV (synchronised intermittent mandatory ventilation), sychonises with the baby for the mandated amount of breaths set by the ventilator; if baby not breathing spontaneously will deliver breaths at the rate set; ventilator will not support extra breaths above the set rate.

14.  Not available on all ventilators  Calculate by babies weight (usual starting point is 4mL/kg. Eg. 3kg baby will have a VG set at 12mLs.  Ventilator will use what PIP is required to achieve that 12mLs of volume (of air) flow into the lungs; so in less compliant lungs more PIP will be required.  Increases or decreases in VG is usually done in 0.5mL/kg changes. Increasing VG will increase CO2 clearance. Decreasing VG will decrease CO2 clearance.

15.  Active inspiration and expiration.  Mean airway pressue  Frequency (5 – 50 Hz 300 – 3000 br/min)  Amplitude  Indications: reduced lung compliance, MAS, lung hypoplasia (eg. With diaphagmatic hernias), pneumonia, atelectasis, air leak, RDS

16.  Gas is ‘squirted’ into the lungs at a very high velocity.  A conventional ventilator is always run in tandem with the jet to generate the PEEP.  Expiration on HFJV is passive from elastic recoil  A special ET adapter is used, it has a jet port through which the HF jet pulses are introduced and a pressure monitoring port for determining the pressures

17.  Minimal handling; GNC 6 -8 hrly or with proceduces  Blood gas monitoring  Hourly observations (SaO2, HR, RR set/actual, PIP, PEEP, MAP, FiO2, VG set/acutal)  Suction PRN, mouth care  Checking of tapes (change if loose, too moist), position of tube (visualise, measure, check most recent CXR)  Medications, feeds  Parent counselling/education

18.  Administered via ETT  Compensates for surfactant deficiency and reduces surface tension of the alveoli  Usually only administered 1 or 2 times in the first 24 hours of ventilation.  Usually given because of high oxygen requirements  Be mindful if not on volume guarantee, PIP’s will likely need to be weaned quickly after administration (because of increase in compliance in the lungs)