Pulse Transit Time (PTT) Measurements During Laparoscopic and Open Abdominal Surgery: A Pilot Study in ASA I-II Female Patients

Background: The pulse transit time (PTT) is the time interval between the R-wave of the ECG and the appear- ance of the pulse wave in the periphery during the same cardiac cycle. PTT is influenced by various factors including sympathetic tone and vascular compliance. The authors assessed the effect of anesthesia, intubation and laparoscopic (LPS) versus laparotomic (LPT) surgery on PTT. Methods: PTT, mean arterial blood pressure (MAP) and heart rate (HR) were measured during induction of anesthesia and during the first 45-min of LPS (n = 17) and LPT (n = 13) surgery in a group of female patients. Results: Anesthesia increased PTT values, while painful stimuli caused an immediate reduction. During surgery, we ob- served group effects on PTT and MAP with 10-25% lower PTT values (P < 0.001) and 15-30% greater MAP values (P < 0.01) in the LPS group. HR did not differ between groups. Conclusions: The pulse transit time was used successfully to track the effect of anesthesia and stressful nociceptive stimuli during induction of anesthesia. The shorter PTT values during laparoscopic abdominal surgery compared to open abdomi- nal surgery suggest a higher sympathetic tone in patients undergoing laparoscopic surgery and/or an effect of the in- creased abdominal pressure on PTT.