BY: NICOLE STEVENS 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) 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) 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 ) 2. Hypoxemia while on 100% O2 3. Or on CPAP (8cm H20) with increasing oxygen requirements (above 40 60%) 4. Severe apnoea Clinical manifestations: Increase or decrease in respiratory rate Increase or decrease in respiratory effort Periodic breathing with increase in respiratory effort Apnoea Manual ventilation (eg. Neopuff) Pressure controlled ventilation Volume controlled ventilation High freqency oscillation ventilation High frequency jet ventilation 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 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 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 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 FiO2 Changes alter alveolar oxygen pressure Flow Minimal effects In general 8 12 litres used Higher flows needed to achieve shorter inspiratory times 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 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. 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. 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 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 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 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, PIPs will likely need to be weaned quickly after administration (because of increase in compliance in the lungs)