Pulmonary atelectasis in children anesthetized for cardiothoracic MR: Evaluation of risk factors

PURPOSE: To systematically assess the frequency and risk factors for atelectasis in children anesthetized for cardiothoracic magnetic resonance (MR). MATERIALS AND METHODS: We retrospectively identified 58 consecutive children (age range, 6 days to 21 years) who underwent cardiothoracic MR from January 2001 to December 2004 whose imaging and medical charts were available. One certificate of added qualification pediatric radiologist and 1 of 2 cardiothoracic radiologists, in consensus, evaluated the first and last set of axial images. Images were evaluated for cardiac, vascular and tracheobronchial abnormalities, and degree of atelectasis. Atelectasis was considered significant if the equivalent of 3 or more segments were involved. Patients received 1 or more of 7 anesthetic medications (n = 27), chloral hydrate alone (n = 4), or required no anesthesia (n = 27). RESULTS: Significant atelectasis developed only in those receiving anesthetic medications. Thirty-seven percent (10/27) of anesthetized children developed significant atelectasis in the first and/or last axial sequence. In 90% (9 /10) of patients, it developed in the first axial sequence. Strong risk factors were age younger than 1 year (80%, 8/10, P = 0.029) and MR evidence of tracheobronchial narrowing (50%, 5/10, P = 0.008). In patients with vascular ring, there was a trend toward significance (40%, 4/10, P = 0.09). None of the anesthesia factors were significant, including ventilation mode, anesthesia duration, or American Society of Anesthesiology risk (all P > 0.1). CONCLUSIONS: Atelectasis may occur shortly after induction of anesthesia in children younger than 1 year of age or with tracheobronchial narrowing when anesthetized for cardiothoracic MR.