Differentiation of skin incision and laparoscopic trocar insertion via
quantifying transient bradycardia measured by electrocardiogram
Background. Most surgical procedures involve structures deeper than the skin.
However, the difference in surgical noxious stimulation between skin incision
and laparoscopic trocar insertion is unknown. By analyzing instantaneous heart
rate (IHR) calculated from the electrocardiogram, in particular the transient
bradycardia in response to surgical stimuli, this study investigates surgical
noxious stimuli arising from skin incision and laparoscopic trocar insertion.
Methods. Thirty-five patients undergoing laparoscopic cholecystectomy were
enrolled in this prospective observational study. Sequential surgical steps
including umbilical skin incision (11 mm), umbilical trocar insertion (11 mm),
xiphoid skin incision (5 mm), xiphoid trocar insertion (5 mm), subcostal skin
incision (3 mm), and subcostal trocar insertion (3 mm) were investigated. IHR
was derived from electrocardiography and calculated by the modern time-varying
power spectrum. Similar to the classical heart rate variability analysis, the
time-varying low frequency power (tvLF), time-varying high frequency power
(tvHF), and tvLF-to-tvHF ratio (tvLHR) were calculated. Prediction probability
(PK) analysis and global pointwise F-test were used to compare the performance
between indices and the heart rate readings from the patient monitor. Results.
Analysis of IHR showed that surgical stimulus elicits a transient bradycardia,
followed by the increase of heart rate. Transient bradycardia is more
significant in trocar insertion than skin incision. The IHR change quantifies
differential responses to different surgical intensity. Serial PK analysis
demonstrates de-sensitization in skin incision, but not in laparoscopic trocar
insertion. Conclusions. Quantitative indices present the transient bradycardia
introduced by noxious stimulation. The results indicate different effects
between skin incision and trocar insertion.
Chang, C-H; Fang, Y-L; Wang, Y-J; Wu, H-T; Lin, Y-T