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Background CNAP® provides continuous non-invasive arterial pressure ( AP) monitoring. We assessed its ability to detect minimal and maximal APs during induction of general anaesthesia and tracheal intubation. Methods Fifty-two patients undergoing surgery under general anaesthesia were enrolled. Invasive pressure monitoring was established at the radial artery, and CNAP monitoring using a finger sensor recording was begun before induction. Statistical analysis was conducted with the Bland- Altman method for comparison of repeated measures and intraclass correlation coefficient ( ICC). Results Patients' median age was 67 years [interquartile range (59-76)], median American Society of Anesthesiologists score was 3 [interquartile range (2-3)]. Bias was 5 and −7 mm Hg for peak and nadir systolic AP ( SAP), with upper and lower limits of agreement of (42:−32) and (27;−42), respectively. The corresponding ICC values were 0.74 [95% confidence interval ( CI) = 0.57-0.84] and 0.60 (95% CI = 0.44-0.73). Time lags to reach these values were 7.5 s (95% CI = −10.0 to 60.0) for the highest SAP and 10 s (95% CI = −12.5 to 72.5) for the lowest SAP. Bias, lower and upper limits of agreement for diastolic, and mean AP were −14 (−36 to 9) and −12 (−37 to 13) for the nadir value and −7 (−29 to 15) and −2 (−28 to 25) for the peak value. Conclusions The CNAP monitor could detect acute change in AP within a reasonable time lag. Precision of its measurements is not satisfactory, and therefore, it could only serve as a clue to the occurrence of changes in AP. [ABSTRACT FROM AUTHOR]