SummaryThe circulatory responses to fibreoptic intubation under general anaesthesia were studied in 60 adult female patients who were randomly assigned to receive either the oral or nasal route for insertion. Non-invasive blood pressure and heart rate were recorded before anaesthesia induction (baseline values), immediately after anaesthesia induction (post-induction values), at intubation and every minute for a further 5 min. The product of heart rate and systolic blood pressure (rate pressure product) at every time point was also calculated. The results showed that both fibreoptic orotracheal intubation and fibreoptic nasotracheal intubation resulted in significant increases in blood pressure, heart rate and rate pressure product compared to baseline and post-induction values. The times required to reach the maximum values of systolic blood pressure and heart rate were significantly longer in the fibreoptic nasotracheal intubation group than in the fibreoptic orotracheal intubation group. There were no significant differences between the two groups in blood pressure, heart rate and rate pressure product at any measuring point, or in the maximum values during observation. The time required for recovery of systolic blood pressure to the postinduction value was not significantly different between the two groups, but the time required for recovery of heart rate to post-induction value was significantly longer in the fibreoptic orotracheal intubation group than in the fibreoptic nasotracheal intubation group. It was concluded that both fibreoptic orotracheal and fibreoptic nasotracheal intubations could cause a similar magnitude of circulatory responses in general anaesthetised, female adults, but the tachycardic response to fibreoptic orotracheal intubation lasted longer than that to fibreoptic nasotracheal intubation. The increasing use of fibreoptic bronchoscopy in clinical anaesthesia has drawn attention to the circulatory responses during fibreoptic intubation. Many relevant studies have been carried out in this field [1][2][3][4][5][6][7][8][9][10][11][12][13], but despite the tremendous differences in the airway stimuli caused by nasal and oral intubations, only one small study [14] has compared the circulatory responses to fibreoptic orotracheal intubation (FOI) and fibreoptic nasotracheal intubation (FNI) under a combination of neuroleptic analgesia and topical anaesthesia. The present randomised clinical study was designed therefore to investigate in a larger sample whether there is a clinically relevant difference between the circulatory responses to FOI and FNI when carried out by experienced practitioners in healthy, female patients receiving general anaesthesia. MethodFollowing ethics committee approval and written informed consent, 60 adult patients, ASA physical status I-II, scheduled for elective plastic surgery under general anaesthesia requiring tracheal intubation, were included in this study. All patients were female, as gender can significantly affect the pressor response to anaesthesia induct...