Misinterpretation of carbon dioxide monitoring because of deadspace of heat and moisture exchanger with a filter in pediatric anesthesia: A case report

RATIONALE: When patients are intubated and treated with mechanical ventilation, the upper respiratory tract is bypassed by the flow of dry and cold air. To prevent disturbances of airway homeostasis, a heat and moisture exchanger filter (HMEF) has been applied to breathing circuit. PATIENT CONCERNS: A 4-month-old male infant was ventilated with the pediatric HMEF. We report the impact of ignoring the direct influence of a filter containing deadspace in pediatric mechanical ventilation. DIAGNOSES: The breathing circuit with HMEF leads to unexpected complications such as mechanical obstructions owing to respiratory secretions, bleeding, inhaled drugs, and moisture. Besides these complications, we generally ignored the deadspace as the internal volume of the filters in breathing circuit for pediatric patients. INTERVENTIONS: After we noticed the influence of filter deadspace for pediatric patient, we removed the filter for effective respiratory circulation. OUTCOMES: The operation was completed without any specific incidents and the patient's voluntary breathing was well-maintained. The patient was discharged without any other complications. LESSONS: The increase in breathing apparatus deadspace should be minimized, and the clinicians should keep in mind that HMEF can causes respiratory acidosis with hypercapnia by apparatus deadspace rebreathing, especially for infants.