Continuous Non-invasive Arterial Pressure Device Research Articles

Postoperative continuous non-invasive cardiac output monitoring on the ward: a feasibility study

Postoperative hypotension is common (occurring in one third of patients) and is associated with worse clinical outcomes. The LiDCO CNAP (continuous non-invasive arterial pressure) device measures haemodynamics but has not been widely adopted in ward environments. Improved early detection of hypotension by CNAP might guide interventions to improve clinical outcomes. We aimed to find the proportion of patients who tolerated LiDCO CNAP for 12 h postoperatively, to unmask episodes of hypotension detected by continuous monitoring and to characterise the haemodynamic profile at the time of hypotension. In this feasibility study, patients undergoing major elective surgery were continuously postoperatively monitored using CNAP. Haemodynamic data gathered from CNAP, including nSVRI (nominal systemic vascular resistance index), nSVI (nominal stroke volume index), SVV (stroke volume variation) and blood pressure, were analysed using Microsoft Excel and GraphPad Prism 8. 104 patients (age (mean ± sd): 68 ± 14, male (56%)) had CNAP sited postoperatively. 39% tolerated the CNAP device for at least 12 h. Within the 104 patients a mean of 81.2 min of hypotension detected by CNAP was not detected by usual care. The proportion of low/normal/high nSVI was 71%, 27% and 2%, nSVRI was 43%, 17% and 40%, respectively. CNAP monitoring was not tolerated for 12 h in the majority of patients. There were many episodes of hypotension unmasked through continuous monitoring. Based on the advanced haemodynamic data provided it is possible that the underlying cause of a third of postoperative hypotensive episodes is vasodilation rather than hypovolaemia.Trial registry number: NCT04010058 (ClinicalTrials.gov) Date of registration: 08/07/2019.

Feasibility of continuous noninvasive arterial pressure monitoring in a prehospital setting, measurements during emergency transfer.

ObjectivesIn severely injured or acutely ill patients close monitoring of blood pressure (BP) can be crucial. At the prehospital scene and during transfer to hospital, the BP is usually monitored using intermittent oscillometric measurements with an upper arm cuff every 3–5 min. The BP can be monitored noninvasively and continuously using the continuous noninvasive arterial pressure (CNAP) device. In this study, we investigated the feasibility of a CNAP device in a prehospital setting.Patients and methodsThe study was an observational convenience study. The CNAP device was applied to the patient once in the ambulance and measurements were carried out during transfer to hospital. The primary object was the number of patients in whom the CNAP device could monitor the BP continuously in a prehospital area en route to hospital.ResultsFifty-nine patients were enrolled in this study. Fifty-four (92%) patients had their BP monitored continuously by the CNAP device. The main reasons for missing data were a mean BP below the detectable range, reduced pulse wave caused by constricted arteries in the fingers, or patients’ excessive movements. The CNAP device provided continuous measurements after a median of 164.5 s. No complications and no adverse events were observed.ConclusionContinuous measurement of the BP obtained by the CNAP device is feasible and safe in a prehospital setting under potentially difficult conditions.

Fluid management guided by a continuous non-invasive arterial pressure device is associated with decreased postoperative morbidity after total knee and hip replacement.

BackgroundThe use of goal directed fluid protocols in intermediate risk patients undergoing hip or knee replacement was studied in few trials using invasive monitoring. For this reason we have implemented two different fluid management protocols, both based on a novel totally non-invasive arterial pressure monitoring device and compared them to the standard (no-protocol) treatment applied before the transition in our academic institution.MethodsThree treatment groups were compared in this prospective study: the observational (CONTROL, N = 40) group before adoption of fluid protocols and two randomized groups after the transition to protocol fluid management with the use of the continuous non-invasive blood pressure monitoring (CNAP®) device. In the PRESSURE group (N = 40) standard variables were used for restrictive fluid therapy. Goal directed fluid therapy using pulse pressure variation was used in the GDFT arm (N = 40). The influence on the rate of postoperative complications, on the hospital length of stay and other parameters was assessed.ResultsBoth protocols were associated with decreased fluid administration and maintained hemodynamic stability. Reduced rate of postoperative infection and organ complications (22 (55 %) vs. 33 (83 %) patients; p = 0.016; relative risk 0.67 (0.49–0.91)) was observed in the GDFT group compared to CONTROL. Lower number of patients receiving transfusion (4 (10 %) in GDFT vs. 17 (43 %) in CONTROL; p = 0.005) might contribute to this observation. No significant differences were observed in other end-points.ConclusionIn our study, the use of the fluid protocol based on pulse pressure variation assessed using continuous non-invasive arterial pressure measurement seems to be associated with a reduction in postoperative complications and transfusion needs as compared to standard no-protocol treatment.Trial registrationACTRN12612001014842Electronic supplementary materialThe online version of this article (doi:10.1186/s12871-015-0131-8) contains supplementary material, which is available to authorized users.

The use of phenylephrine to obtund oxytocin-induced hypotension and tachycardia during caesarean section

BackgroundOxytocin causes clinically significant hypotension and tachycardia. This study examined whether prior administration of phenylephrine obtunds these unwanted haemodynamic effects. MethodsForty pregnant women undergoing elective caesarean section under spinal anaesthesia were randomised to receive either an intravenous 50μg bolus of phenylephrine (Group P) or saline (Group S) immediately before oxytocin (3U over 15s). Systolic blood pressure, diastolic blood pressure, mean arterial pressure and heart rate were recorded using a continuous non-invasive arterial pressure device. Baseline values were averaged for 20s post-delivery. Between-group comparisons were made of the mean peak changes in blood pressure and heart rate, and the mean percentage changes from baseline, during the 150s after oxytocin administration. ResultsThe mean±SD peak percentage change in systolic blood pressure was −16.9±2% in Group P, and −19.0±1.9% in Group S and the estimated mean difference was 2.1% (95% CI −3.5% to 7.8%; P=0.44); corresponding changes in heart rate were 13.5±2.3% and 14.0±1.5% and the mean estimated difference was 0.5% (95% CI −6.0% to 5%; P=0.87). The mean percentage change from the baseline measurements during the 150s period of measurement was greater for Group S than Group P: systolic blood pressure −5.9% vs −3.4% (P=0.149); diastolic blood pressure −7.2% vs −1.5% (P=0.014); mean arterial pressure −6.8% vs −1.5% (P=0.007); heart rate 2.1% vs −2.4% (P=0.033). ConclusionIntravenous phenylephrine 50μg immediately before 3U oxytocin during elective caesarean section does not prevent maternal hypotension and tachycardia.

Evaluation of continuous non-invasive arterial pressure monitoring during induction of general anaesthesia in patients undergoing cardiac surgery.

Background and Aims:Continuous arterial pressure monitoring is essential in cardiac surgical patients during induction of general anaesthesia (GA). Continuous non-invasive arterial pressure (CNAP) monitoring is fast gaining importance due to complications associated with the invasive arterial monitoring. Recently, a new continuous non-invasive arterial pressure device (CNAP™) has been validated perioperatively in non-cardiac surgeries. The aim of our study is to compare and assess the performance of CNAP during GA with invasive arterial pressure (IAP) in patients undergoing cardiac surgeries.Methods:Sixty patients undergoing cardiac surgery were included. Systolic, diastolic, and mean arterial pressure (MAP) data were recorded every minute for 20 min simultaneously for both IAP and CNAP™. Statistical analysis was performed using mountain plot and Bland Altman plots for assessing limits of agreement and bias (accuracy) calculation. Totally 1200 pairs of data were analysed.Results:The CNAP™ systolic, diastolic and MAP bias was 5.98 mm Hg, −3.72 mm Hg, and − 0.02 mm Hg respectively. Percentage within limits of agreement was 96.0%, 95.2% and 95.7% for systolic, diastolic and MAP. The mountain plot showed similar results as the Bland Altman plots.Conclusion:We conclude CNAP™ provides real-time estimates of arterial pressure comparable to IAP during induction of GA for cardiac surgery. We recommend CNAP can be used as an alternative to IAP in situations such as cardiac patients coming for non-cardiac surgeries, cardiac catheterization procedures, positive Allen's test, inability to cannulate radial artery and vascular diseases, where continuous blood pressure monitoring is required.

Detection of Hypotension During Caesarean Section With Continuous Noninvasive Arterial Pressure Device or Intermittent Oscillometric Arterial Pressure Measurement

Detection of Hypotension During Caesarean Section With Continuous Noninvasive Arterial Pressure Device or Intermittent Oscillometric Arterial Pressure Measurement

Detection of Hypotension During Cesarean Section With Continuous Noninvasive Arterial Pressure Device or Intermittent Oscillometric Arterial Pressure Measurement

Detection of Hypotension During Cesarean Section With Continuous Noninvasive Arterial Pressure Device or Intermittent Oscillometric Arterial Pressure Measurement

Detection of Hypotension During Caesarean Section With Continuous Non-Invasive Arterial Pressure Device or Intermittent Oscillometric Arterial Pressure Measurement

Ilies, C.*; Kiskalt, H.†; Siedenhans, D.†; Meybohm, P.*; Steinfath, M.*; Bein, B.*; Hanss, R.* Author Information

Detection of hypotension during Caesarean section with continuous non-invasive arterial pressure device or intermittent oscillometric arterial pressure measurement

The intensified use of spinal anaesthesia (SPA) for Caesarean section significantly contributed to a decreased maternal mortality and morbidity. Nevertheless, one of the major side-effects is hypotension after SPA with potential negative effects on the fetus. Owing to discontinuous oscillometric measurements (non-invasive arterial pressure, NIAP), hypotensive episodes may be missed. Recently, a continuous NIAP measurement device (CNAP) with acceptable agreement with the mean invasive AP was introduced. We hypothesized that CNAP detects hypotensive episodes more reliably compared with NIAP measurements. A total of 65 women undergoing Caesarean section under SPA were included in the study analysis. A total of 888 NIAP measurements obtained at 3 min cycles, starting from before SPA and continued until delivery, were analysed. When averaged over all cycles, the lowest systolic AP identified by CNAP in each cycle [105 mm Hg, (24.4)] was significantly lower (P<0.001) than the average of the individual corresponding single NIAP measurements [126 mm Hg (22.1)] and highest CNAP average [126 mm Hg (24.5)]. Hypotension (systolic AP <100 mm Hg) was detected in 39% of all cycles with CNAP and in 9% with NIAP. Hypotension was detected in 91% of the patients based on CNAP and in 55% based on NIAP. Fetal acidosis defined by an umbilical vein pH under 7.25 did not occur when the lowest systolic AP measured by CNAP was above 100 mm Hg. The CNAP device detected more hypotensive episodes after SPA and significantly lower AP compared with NIAP. AP monitoring based on CNAP may improve haemodynamic management in this patient population with potential benefit for the fetus.

Investigation of the agreement of a continuous non-invasive arterial pressure device in comparison with invasive radial artery measurement

Arterial pressure (AP) monitoring should be accurate, easy to use, free of risks, and ideally continuous. The continuous non-invasive arterial pressure (CNAP) device is non-invasive and provides continuous pressure readings. This study was performed to compare the agreement of CNAP and invasive AP monitoring. Ninety patients undergoing surgery under general anaesthesia were enrolled. Invasive pressure monitoring was established at the radial artery. CNAP monitoring using a finger sensor recording was begun before induction of anaesthesia. Statistical analysis was conducted with the Bland-Altman method for comparisons of repeated measures. We obtained 16 843 valid pressure readings from 85 patients. Mean (sd) bias during maintenance of anaesthesia was: systolic AP: 4.2 (16.5) mm Hg; mean AP (MAP): -4.3 (10.4) mm Hg; and diastolic AP: -5.8 (6) mm Hg. The results of a subgroup analysis of patients who had a mean intra-arterial pressure of <70 mm Hg were as follows: systolic pressure: -0.3 (9.7) mm Hg; mean pressure: -6.8 (7.6) mm Hg; and diastolic pressure: -7.9 (7.2) mm Hg. Bias and percentage error during the induction period were greater in both the main and subgroup analyses, probably due to recalibration being omitted after induction. The CNAP monitor showed an acceptable agreement and was interchangeable with invasive pressure monitoring for MAP during normotensive conditions. During induction of anaesthesia and when the AP was low, the agreement was less good and interchangeability was not achieved. These results suggest that CNAP is not statistically equivalent to invasive monitoring during all periods of anaesthesia but may be a useful additional AP monitor.

Validation of a new continuous non-invasive arterial pressure device in post-surgical patients

Rico-Feijoo, J.; Lopez-Zayas, E.; Arias, D.; Aldecoa, C.; Gomez-Herreras, J. Author Information