Figure 1.

Tracing showing the relationship between systolic noninvasive intermittent blood pressure and pulse arrival time during laryngeal microscopic surgery. Beat-to-beat changes in pulse arrival time instantaneously reflected marked perturbations of systolic noninvasive intermittent blood pressure during endotracheal intubation and the beginning of the laryngeal microsurgery procedure. The insets show the electrocardiography (upper) and the photoplethysmographic waveform (bottom) results before and after the insertion of the laryngeal microscope. The thick blue line is the smoothed line of the PAT using locally estimated scatterplot smoothing.