Assessment of different techniques for the administration of inhaled salbutamol in children breathing spontaneously via tracheal tubes, supraglottic airway devices, and tracheostomies

Background: Perioperative respiratory adverse events account for a third of all perioperative cardiac arrests, with bronchospasm and laryngospasm being most common. Standard treatment for bronchospasm is administration of inhaled salbutamol, via pressurized metered dose inhaler. There is little evidence on the best method of attaching the pressurized metered dose inhaler to the artificial airway during general anesthesia. Aim: The aim of this study is to investigate the best method to deliver aerosolized salbutamol via pressurized metered dose inhaler to the lungs of an anesthetized child. Methods: We measured salbutamol delivered by pressurized metered dose inhaler through different sized tracheal tubes, supraglottic airway devices, and tracheostomies in vitro for methods commonly employed for connecting the pressurized metered dose inhaler to the artificial airway. Breathing was simulated for patients weighing 3, 16, 50, and 75 kg. Pressurized metered dose inhaler actuation coincided with inspiration. Results: A pressurized metered dose inhaler combined with an in-line non-valved or valved spacer, or the direct method, when delivered via tracheal tube, was linked with improved delivered dose of salbutamol, compared to all other methods for 3 or 50 kg simulated patients weights. The delivered dose when using a non-valved spacer was greater than all methods for 16 and 75 kg patient weights. A spacer improved delivery for the flexible supraglottic airway device type, and there was no difference with or without a spacer for remaining types. Conclusion: Via tracheal tube and non-valved spacer, the following doses should be delivered after single actuation of a 100 µg labeled-claim salbutamol dose: ~2 µg kg⁻¹ per actuation to a 3 kg neonate, ~1 µg kg⁻¹ per actuation to a 16 kg child, and ~ 0.5 µg kg⁻¹ per actuation for a 50–75 kg child. The least effective methods were the syringe, and the uni- and bidirectional adaptor methods, which require replacement by the direct method if a spacer is unavailable.