Ketamine is an N-Methyl-d-aspartate-receptor-antagonist commonly used over the last decades as an anesthetic and analgesic agent for procedural sedation. The use of ketamine as a prolonged infusion was first described in 1990 and a prolonged infusion of ketamine has been described as a successful strategy for analgesia and sedation in patients with hemodynamic instability, in patients who were mechanically ventilated and poorly responsive to conventional drugs. An other indication for ketamine infusion is the presence of bronchospasm, due to its action in promoting bronchodilatation. However, existing studies on ketamine for prolonged sedation are mainly retrospective and include small sample size, suggesting that this topic needs to be further investigated. The aim of this observational single center study is to describe the use of ketamine used as adjuvant to conventional analgesic and sedative strategy (opioid and benzodiazepine in continuous infusion) as prolonged infusion (i.e. 12 hr) in pediatric patients. The investigators will evaluate ketamine indications, dosages, infusion duration, adoption of boluses, modality of weaning. Concomitant analgesic and sedative management and monitoring of level of sedation (using a validated scale) are considered measures of efficacy. Sparing of other bronchospasm drugs sedative dosage are considered measures of efficacy if ketamine is used in patients with obstructive respiratory diseases. Presence of adverse effects (including withdrawal syndrome symptoms and delirium) during infusione or 48 hours after weaning are considered measures of safety. Data were collected using a standardized data sheet. The study lasted 18 months to reach a numerosity of 55 patients. All the requested institutional approvals were collected before starting the data collection.