aUniversity of Otago: Christchurch, Christchurch, Aotearoa

bTe Whatu Ora, Waitaha, Canterbury, New Zealand

Correspondence to R Ross Kennedy, MB, ChB, PhD, FANZCA, Clinical Associate Professor, Department of Anaesthesia, Christchurch Hospital, Rolleston Avenue, Christchurch, Aotearoa, New Zealand. Tel: +64 3 3640 288; e-mail: [email protected]