Anesthetic considerations for thoracic neurosurgical procedures

Effect of high-frequency oscillation and percussion versus conventional ventilation in a piglet model of meconium aspiration

BACKGROUND

Meconium aspiration syndrome (MAS) remains a frequent cause of morbidity and mortality in term newborns. Our objective was to compare two modes of high-frequency ventilation, high-frequency oscillation (HFOV), and high-frequency percussive ventilation (HFPV) with conventional mechanical ventilation (CMV) in a piglet model of MAS.

METHODS

Fifteen newborn piglets were anesthetized, paralyzed, and intubated. Following the instillation of a 3 ml/kg solution of meconium diluted to 30%, the piglets were randomized to one of three groups: high-frequency oscillation (HFOV; Sensormedics®), HFPV (Percussionaire®), or CMV (Siemens®). Animals were ventilated for 6 hr to maintain arterial blood gases within a normal range, that is, pH 7.35-7.45, PaO(2) 10-16 kPa, PaCO(2) 4-6.6 kPa. Arterial blood gas measurements, dynCrs and dynRrs, ventilator settings, and vital signs (heart rate, arterial blood pressure, transcutaneous pulse oxygen saturation, and temperature) were collected at 30, 60, 90, 120, 180, 240, 300, and 360 min after meconium instillation. Oxygenation index (OI) ([(fraction of inspired oxygen)(mean airway pressure)(100)]/PaO(2) ), mean airway pressure, dynamic lung function, secretions cleared and histological alterations were studied in all groups.

RESULTS

Mean airway pressure and OI were significantly lower in the CV and HFPV groups compared to the HFOV group (P < 0.05). There was no significant difference between groups regarding lung function, amount of secretions and histological alterations.

CONCLUSION

In our model of MAS in piglets, whilst effective gas exchange with a lower mean airway pressure was possible with both CMV and HFPV compared with HFOV there was no apparent difference in lung histology or secretions.