Background: Second-derivative of photoplethysmography (SDPTG) is a non-invasive method for the assessment of structural and functional arterial properties. We studied the hemodynamic responses to induction of anaesthesia and whether SDPTG could be used in predicting these responses.
Methods: SDPTG was performed in 71 subjects (35 males, 36 females) undergoing general anaesthesia for elective operation. Anaesthesia was inducted with propofol 2 mg x kg(-1), fentanyl 2 microg x kg(-1), vecuronium 0.1 mg x kg(-1), and sevoflurane 3% in a mixture of 100% oxygen.
Results: The SDPTG indices (b/a and d/a values) significantly correlated with the percentage decrease in systolic blood pressure in both genders. Regression equations (x = SDPTG indices, y = percentage of decrease in systolic blood pressure) were as follows: (1) b/a, r(male) = 0.39, P < 0.05, y = 23.26x + 40.67; r(female) = 0.39, P < 0.05, y = 17.95x + 39.61; (2) d/a, r(male) = -0.37, P < 0.05, y = -31.29x + 16.22 and r(female) = -0.48, P < 0.01, y = -34.46x + 18.55.
Conclusions: These results suggest that preoperative SDPTG is useful in predicting the hemodynamic response to induction of general anaesthesia.