Objective: To assess if intramuscular suxamethonium 0.5 mg . kg-1 administered to cats during general anaesthesia results in immobilisation without disturbance of spontaneous breathing. To assess optimal dose of intramuscular suxamethonium in adult humans. Design: Prospective experimental study in cats, prospective clinical study in humans. Materials and methods: Suxamethonium 0.5 mg . kg-1 was administered in the hind paw of cats anaesthe-tised with a medetomidine-ketamine combination. Muscle relaxation was measured using accelerograph TOF Watch SX and cardiorespiratory monitoring was performed by pulse oximetry. A pilot study was per-formed in humans to assess the optimal suxamethonium dose. The main study was performed in 10 pati-ents ASA 1-2. Suxamethonium 3 mg . kg-1 was administered in the deltoid muscle. The depth of muscle relaxation was measured by TOF Watch SX, the conditions for tracheal intubation were assessed by an accompanied scale. Results: Suxamethonium 0.5 mg . kg1administered to cats resulted in immobilisation with preserved spontaneous ventilation. In adult humans, good conditions for tracheal intubation were achieved 3-3.5 minutes after intramuscular suxamethonium 3 mg . kg-1. Conclusion: Immobilisation with preserved spontaneous breathing in cats can be achieved with intramuscular suxamethonium, but the therapeutic range is low. Intramuscular suxamethonium can be ušed for emergency tracheal intubation not only in children but also in adults.

        Key words: suxamethonium - animal immobilization - intramuscular administration - use in adults