Introduction Oesophageal intubation activates a complex stress response, mediated in part by the autonomic nervous system (ANS) (1). Measurement of ANS tone at intubation is thus a useful method of assessing the duration of the physiological stress response which may influence any subsequent measurement of oesophageal sensory-motor function. For instance, it is known that both ANS tone and psychological factors such as the personality trait of neuroticism and anxiety levels, influence oesophageal sensitivity to distension (1). However, factors that influence recovery of ANS tone following intubation are incompletely understood. Thus the aim of the study was to evaluate the ANS response to oesophageal intubation and to identify whether personality traits influence its recovery to baseline.
Methods 50 healthy subjects (25 male, mean age 38.1 years, range 21–59 years) had personality traits, using the validated Big-Five Inventory (BFI), and anxiety levels, using the validated Spielberger State/Trait Anxiety Inventory (STAI). ANS tone was assessed using cardiac vagal tone (CVT) which is a validated measure of brainstem mediated parasympathetic (PNS) efferent tone at baseline (10 minutes) & continuously thereafter in addition to heart rate (HR) and mean arterial blood pressure (MBP) which are mixed measures of PNS and sympathetic tone. Subjects were then intubated with a naso-oesophageal catheter, without the aid of local anaesthetic, and monitored for a further 20 minutes.
Results All subjects tolerated the study well. The mean BFI neuroticism score (BFI-N) was 2.86 (range 1–5). The mean baseline HR, MBP and CVT was 65 beats per minute (range 48–88), 87 mmHg (range 68–104) and 7.8 (range 2.2–14.1) respectively. As expected, naso-esophageal intubation caused a significant elevation in HR (p < 0.0001) and MBP (p < 0.0001) with associated CVT withdrawal (p = 0.001). The mean recovery time of CVT to baseline was 4.5 minutes (range 1.1 – 14.9). BFI-N, state STAI and trait STAI were positively correlated with recovery time (r = 0.86, p < 0.0001; r = 0.48, p < 0.0001; r = 0.58, p < 0.0001).
Conclusion Naso-oesophageal intubation results in the withdrawal of PNS tone and an increase in HR and MBP and the speed of recovery to baseline of PNS tone is correlated with neuroticism. Future studies should allow for at least 15 minutes of recovery time after intubation before any physiological assessments are made and consideration should be given to psychological trait measures as these can influence the recovery of stress response to intubation.
Disclosure of Interest None Declared
Paine et al. Pain 2011