Preoperative evaluation The main indications for tonsillectomy are recurrent infections and in particular obstructive sleep apnoea (OSA), which is characterised by restless sleep and snoring with apnoeic pauses [3]. In severe cases, failure to thrive, impaired cognitive scores and even pulmonary hypertension with cor pulmonale may occur. Normal children have a smaller upper airway; nevertheless, they snore less and have less apnoea. In children with OSA, however, the upper airway is no longer resistant to collapse during sleep or pharmacological sedation [4]. It is of great importance to recognise these patients with OSA in advance. They may need special skills to keep the airway open during induction [5], they are more sensitive to sedative drugs, for example opioids [6], and postoperative monitoring is mandatory (Table 1). Despite removal of obstructive lymphoid tissue upper airway obstruction can occur in the first postoperative night; however, the upper airway neuromotor response, preventing the collapse of the airway during sleep, recovers at least partially over time after treatment [4]. A patient’s age below 2 years, pre-existing muscle hypotony, failure to thrive and craniofacial abnormalities should raise additional concerns [7].