Clinical validation of the Air-Test for the non-invasive detection of perioperative atelectasis in children

Abstract

Background: The incidence of anesthesia-induced atelectasis in children is high and closely related to episodes of hypoxemia. The Air-Test is a simple maneuver to detect lung collapse. By a step-reduction in FiO<inf>2</inf> to 0.21, a fall in pulse-oximetry hemoglobin saturation <97% unmasks the presence of collapse-related shunt in healthy lungs. The aim of this study was to validate the Air-Test as a diagnostic tool to detect perioperative atelectasis in children using lung ultrasound as a reference.

Methods: We first assessed the Air-Test in a retrospective cohort of 88 anesthetized children (Retrospective study) followed by a prospective study performed in 72 children (45 postconceptional weeks to 16 years old) using a similar protocol (Validation study). We analyzed the performance of the Air-Test to detect atelectasis by an operating characteristic curve (ROC) analysis, using lung ultrasound consolidation score as reference.

Results: Preoperative SpO<inf>2</inf> was normal in both studies (retrospective 98.7±0.6%, validation 99.0±0.9%). The Air-Test, with a SpO<inf>2</inf> cut point <97%, resulted positive in 67 patients in the retrospective study (SpO<inf>2</inf> 93.3±2.1%) and in 59 in the validation study (SpO<inf>2</inf> 94.9±1.8%); both P<0.0001. In the validation study, the Air-Test showed a sensitivity of 0.91 (95% CI 0.85-0.92), specificity of 1.00 (95% CI 0.84-1) and an area under the curve (AUC) of 0.98 (95% CI 0.97-1.00). AUC between both studies was similar (P=0.16).

Conclusions: The Air-Test is a noninvasive and accurate method to detect atelectasis in healthy anesthetized children. It can be used as a screening tool to individualize patients that can benefit from lung recruitment maneuvers.