Key result
CNAP showed acceptable agreement with invasive arterial pressure for mean blood pressure (bias 4.5 mmHg), but reduced precision for systolic and diastolic pressures, especially in older patients.
Why the study?
Whether the accuracy of the CNAP continuous noninvasive blood pressure monitor changes with age and its detectability of hypertension and hypotension remained unclear.
Does the CNAP monitor accurately measure blood pressure and detect hypertension/hypotension compared to invasive arterial pressure in patients undergoing surgery under general anesthesia?
Observational (n=48)
No
Does the CNAP monitor accurately measure blood pressure and detect hypertension/hypotension compared to invasive arterial pressure in patients undergoing surgery under general anesthesia?
Mean Difference: 4.5 (95% CI -12.5–21.5)
The CNAP monitor shows acceptable agreement with invasive arterial pressure for mean blood pressure but reduced agreement for systolic and diastolic pressures, especially in older patients, and is less reliable for detecting hyper/hypotension episodes.
CNAP agreement with IAP weakens for SBP/DBP in older patients; leaves open reliability for detecting hypertension/hypotension episodes.
BACKGROUND: CNAP monitor is a continuous and noninvasive blood pressure (BP) measurement device that can be used in intraoperative monitoring. But whether its accuracy changes with age and its detectability of hypertension and hypotension are still unclear. This study was to investigate the agreement of CNAP and invasive arterial pressure (IAP) in different age groups, and the ability of CNAP to detect hypertension and hypotension. METHODS: This observational study enrolled 48 Chinese patients undergoing surgery under general anaesthesia, including 25 relatively old patients (age between 50 and 70) and 23 relatively young patients (age between 18 and 49). IAP was monitored at the radial artery and CNAP was applied on the opposite arm simultaneously. Paired BP data in the entire surgery were recorded, and analyzed with Bland Altman plot and Spearman correlation. The ratio of the hypertension and hypotension episodes detected by IAP and CNAP was analyzed using chi-square test. RESULTS: 7990 valid paired BP data were analyzed, wherein 4186 data were from 25 relatively old patients, and the other data were from 23 relatively young patients. Bias (SD) for relatively old patients was: systolic BP (SBP): - 6.5 (18.6) mm Hg; diastolic BP (DBP): 9.3 (7.8) mmHg; and mean BP (MBP): 4.2 (9.5) mm Hg. Bias (SD) for relatively young patients was: SBP: - 6.2 (12.1) mm Hg; DBP: 10.6 (6.9) mmHg; and MBP: 4.8 (7.3) mm Hg. The correlation between CNAP and IAP was higher in MBP than those in SBP and DBP, and it decreased with the increase of age. Comparing to IAP, CNAP tended to miss reporting a high SBP, low DBP and low MBP, and misinform a low SBP, high DBP and high MBP. CONCLUSION: CNAP showed acceptable agreement with IAP in MBP for all age groups, but reduced agreement with IAP in SBP and DBP, especially for relatively old patients. Ability of CNAP to detect hypertension and hypotension episodes was weaker than IAP. Therefore, CNAP monitor is suitable for young patients and hemodynamically stable surgery, but may not be recommended for old patients with arteriosclerosis and diabetes or surgeries expecting to have fluctuating blood pressure.
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Wang et al. (2019) conducted an observational in Perioperative blood pressure monitoring (n=48). CNAP monitor vs. Invasive arterial pressure (IAP) was evaluated on Agreement (bias) between CNAP and IAP for mean blood pressure (MBP) (Bias 4.5 mmHg, 95% CI -12.5 to 21.5). CNAP showed acceptable agreement with invasive arterial pressure for mean blood pressure (bias 4.5 mmHg), but reduced precision for systolic and diastolic pressures, especially in older patients.
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