Diagnostic accuracy of the HUAWEI WATCH D for measuring spinal anesthesia-induced hypotension during elective cesarean section: a diagnostic test

The newly developed HUAWEI WATCH D (HW) is a wearable smartwatch, primarily designed to measure non-invasive blood pressure (NIBP) at the wrist. Two recent studies have demonstrated that the accuracy of HW is the same as that of mercury sphygmomanometer for measuring BP in adults. This study aimed to validate the accuracy of the HW in hypotension monitoring.

A total of 118 healthy parturients with singleton pregnancies undergoing elective cesarean section were included. BP was measured three times preoperatively on the left wrist using HW and on the right upper limb using an Omron BP monitor, with the respective mean values recorded as the baseline values in the supine position. After spinal anesthesia, bilateral BP was measured simultaneously by HW and a NIBP monitor at 1-min intervals, 10 times. The primary outcome was the Chi-squared test results comparing hypotension detected between HW and NIBP, as well as the area under the curve (AUC) for receiver operating characteristic (ROC), the Youden index, and the cut-off point of HW for measuring hypotension.

Overall, 1180 pairs of systolic blood pressure (SBP) were measured. Using an SBP of <80% baseline values of NIBP as the gold standard for hypotension, Youden Index = 0.62, the hypotension threshold for HW is set to 104 mmHg, with sensitivity of 79.2%, specificity of 82.0%, false positive rate of 18.0%, and false negative rate of 20.8%, and accuracy of 81.3%. The Chi-squared test yielded a Pearson γ² = 350.4, Kappa = 0.53, P < 0.001 (two-tailed). The AUC of ROC was 0.87 (95% confidence interval: 0.85-0.90), P < 0.001 (two-tailed).

The HUAWEI WATCH D demonstrates moderate diagnostic accuracy for detecting severe hypotension (SBP < 80% baseline) during caesarian section under spinal anesthesia, with a sensitivity of 79.2%, a specificity of 82.0%, and an AUC of 0.87.