SEVERE PAROXYSMAL SINUS BRADYCARDIA ASSOCIATED WITH HIGH-FREQUENCY OSCILLATORY VENTILATION

Objective: To determine the incidence of and risk factors for unexplai ned paroxysmal bradycardia in children treated with high-frequency osc illatory ventilation (HFOV). Design: A nested case-control study. Sett ing: A university-affiliated children's hospital. Subjects: All childr en treated with HFOV for at least 3 days during a 2-year period and a randomly chosen comparison group of 50 children treated with only conv entional mechanical ventilation (CMV) for at least 3 days during the s ame time period. Interventions: None. Measurements and results: Unexpl ained paroxysmal sinus bradycardia occurred in six children (12%) rece iving HFOV, and was significantly more common than in children treated with CMV (0%). The bradycardic events occurred after the lung disease started to improve, and the mean airway pressure (mPaw) at the time o f the bradycardias was significantly decreased from the child's maxima l mPaw. The bradycardic events were effectively treated acutely with m anual ventilation or atropine sulfate, and resolved completely after t he patient was changed to a regimen of CMV. Conclusion: Unexplained pa roxysmal bradycardia associated with HFOV in children is not uncommon. It completely resolves with conversion to CMV and may be related to o verdistention of alveoli as compliance improves.