Abstract
BackgroundCNAP 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.MethodsThis 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.Results7990 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.ConclusionCNAP 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.
Highlights
CNAP monitor is a continuous and noninvasive blood pressure (BP) measurement device that can be used in intraoperative monitoring
The results indicated that CNAP monitor showed an acceptable agreement with invasive and oscillometric pressure for mean arterial pressure (MAP)
The Bland–Altman plots for systolic BP (SBP), diastolic BP (DBP), and mean BP (MBP) were calculated for all the patients (Fig. 1), the relatively old group (Fig. 2) and the relatively young group (Fig. 3)
Summary
CNAP monitor is a continuous and noninvasive blood pressure (BP) measurement device that can be used in intraoperative monitoring. The invasive arterial line provides continuous monitoring and high accuracy, but it is technically demanding and has risk of complications such as trauma, bleeding, infection, thrombosis, embolism, distal ischemia, and the formation of a pseudoaneurysm [1, 2]. It is mostly used in high-risk operations or critically ill patients. The oscillometric pressure device is used in most surgical procedures for blood pressure monitoring due to it is non-invasive and easy to use It can only provide intermittent measurement (e.g., every 3-5 min), may not reflect the changes in blood pressure timely and effectively. Inadequate diagnosis and delayed treatment of the changes in blood pressure may increase postoperative complications and mortality [3,4,5]
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