Positional OSA part 1: towards a clinical classification system for position-dependent obstructive sleep apnoea

Background In 1984, Cartwright suggested that physicians should differentiate between patients with either positional obstructive sleep apnoea (POSA) or non-positional OSA. Treatment of POSA has advanced dramatically recently with the introduction of a new generation of positional therapy (PT), a small device attached to either the neck or chest which corrects the patient from adopting the supine position through a vibrating stimulus. Encouraging data have been published suggesting that this simple therapy successfully prevents patients with POSA from adopting the supine position without negatively influencing sleep efficiency, as well as allowing for good adherence. Unfortunately, evaluating the efficacy of PT and comparing results are hindered by the fact that there are no universally used POSA criteria. In 1984, Cartwright introduced the arbitrary cut-off point of a difference of 50 % or more in apnoea index between supine and non-supine positions.