Use of High Flows in Pediatric Cardiac Surgical Patients

Use of High Flow Ventilation in Pediatric Cardiac Surgical Patients

Humidified high flow nasal prong oxygen therapy is a method for providing oxygen and CPAP. The delivery of high flows decreases dilution of the inhaled oxygen and, by matching patient's peak flow, allows accurate delivery of the set FiO2 throughout the whole inspiratory phase. In addition, a flow-dependent effect of continuous positive airway pressure, possibly due to an air entrainment mechanism, has been documented in healthy volunteers and in patients with COPD.

The investigators working hypothesis is that the use of post-extubation CPAP delivered via nasal cannulae in infants less than 18 months, post-bypass surgery will have better PaCO2 values than infants extubated on to oxygen therapy.

After CICU admission, infants with no bleeding, normothermic and hemodynamically stable will be switched from PRVC to SIMV+PSV (10-15cmH20) which should be maintained for 4 hours. An arterial gas analysis will be performed after 20 minutes. Infants with normal gas-exchange are gradually weaned from mechanical ventilation At each weaning step an arterial hemogasanalysis is performed after 20 minutes, to assess if the decreased ventilatory support is tolerated. Increased work of breathing and respiratory acidosis (ph< 7.3 or pCO2 > 60 mmHg) are considered criteria to withhold the weaning process. After a 4 hour period on SIMV+PSV the child should be switched to PSV for 30 minutes and then extubated. The following extubation criteria should be reached:

• Satisfactory blood gases with PCO2 under 45mmHg, pH greater than 7.30.
• Fractional inspired oxygen concentration of 65% and or less than the baseline value
• Adequate respiratory frequency according to age without dyspnea

At this point criteria for extubation are reached. Once extubation has taken place the child will be placed either on traditional oxygen therapy or high flow nasal cannulae according to randomization.

Inclusion Criteria:

• Age: 0-18 months
• Mechanical Ventilation via an endotracheal tube
• Elective surgery
• Post-bypass procedure
• Rachs 2 and above

Exclusion Criteria:

• Presence of major congenital malformations
• Presence of neuromuscular disease
• Presence of non drained pneumothorax
• Absent respiratory drive or recurrent apneas
• Hemodynamic instability
• Glasgow coma score (GCS) less than 8
• ECG with evidence of ischaemia or arrhythmias
• Active bleeding