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[Efficacy of pressure support ventilation general anesthesia in infants and premature patients undergoing ophthalmologic surgeries].

OBJECTIVE
To investigate the efficacy of pressure support ventilation (PSV) general anesthesia in infants and premature patients undergoing ophthalmologic surgeries.


METHODS
A total of forty-two infants undergoing vitreoretinal surgeries in Peking university people's hospital from Dec. 2014 to Jul. 2015 were enrolled in the study, whose post-conceptual age (PCA, duration from the mother's last menstrual period to the date surgery was performed) were 38-92 weeks. They were divided into 3 groups according to PCA, which were group A (PCA ≤ 44 weeks), group B (44 weeks < PCA ≤ 64 weeks) and group C (64 weeks < PCA ≤ 92 weeks). Anesthesia was induced with 6% sevoflurane inhalation by mask. After placement of laryngeal mask airway, patients were breathing spontaneously during the whole procedure with the inhalational maintenance concentration of sevoflurane and ventilation parameters adjusted according to clinical set. The surgical procedure begun when satisfying retrobulbar nerve block was achieved. The end-tidal concentration- of sevoflurane, hemodynamic and respirational data were recorded at the time of before surgery (T0), 15 minutes after surgery (T1) and 30 minutes after surgery (T2). The time interval from cease of sevoflurane inhalation to the laryngeal mask removal and adverse events during and after surgery were also recorded.


RESULTS
A total of 42 patients were enrolled in the study, with 10 cases in group A, 17 cases in group B and 15 cases in group C. The hemodynamics of all patients in three groups were stable. There was no significant difference in removal time interval among groups (all P > 0.05). No significant difference was found in end-tidal concentrations of sevoflurane, minute ventilation, pressure of end-tidal carbon dioxide, lung compliance among three time points(all P > 0.05). The respiration rate (per minute) of group B and group C were (33.1 ± 5.7) and (29.4 ± 6.4) at T1, (35.8 ± 7.4) and (32.1 ± 5.6) at T0, respectively, with statistical difference (F = 5.087, 5.628; P < 0.05) at both time points between groups. The peak airway pressure (cmH2O) of group B and group C were (14.5 ± 3.1) and (14.3 ± 2.2) at T1, (14.1 ± 2.9) and (13.1 ± 1.5) at T0, respectively, with statistical difference (F = 4.923, 12.393; P < 0.05) at both time points between groups. There was no significant difference in end-tidal concentrations of sevoflurane, pressure of end-tidal carbon dioxide, expiratory tidal volume per kg, minute ventilation per kg, respiration rate and peak airway pressure among groups (all P > 0.05). There was no severe adverse events during and after surgery in any group.


CONCLUSION
The application of PSV during laryngeal mask airway general anesthesia with spontaneous breathing maintained can be a choice for infants and premature patients undergoing ophthalmologic surgeries.