Impact of non invasive and beat-to-beat arterial pressure monitoring on intraoperative hemodynamic management

Continuous vs intermittent Non-Invasive blood pressure MONitoring in preventing postoperative organ failure (niMON): study protocol for an open-label, multicenter randomized trial

BACKGROUND

Blood pressure has become one of the most important vital signs to monitor in the perioperative setting. Recently, the Italian Society of Anesthesia Analgesia Resuscitation and Intensive Care (SIAARTI) recommended, with low level of evidence, continuous monitoring of blood pressure during the intraoperative period. Continuous monitoring allows for early detection of hypotension, which may potentially lead to a timely treatment. Whether the ability to detect more hypotension events by continuous noninvasive blood pressure (C-NiBP) monitoring can improve patient outcomes is still unclear. Here, we report the rationale, study design, and statistical analysis plan of the niMON trial, which aims to evaluate the effect of intraoperative C-NiBP compared with intermittent (I-NiBP) monitoring on postoperative myocardial and renal injury.

METHODS

The niMon trial is an investigator-initiated, multicenter, international, open-label, parallel-group, randomized clinical trial. Eligible patients will be randomized in a 1:1 ratio to receive C-NiBP or I-NiBP as an intraoperative monitoring strategy. The proportion of patients who develop myocardial injury in the first postoperative week is the primary outcome; the secondary outcomes are the proportions of patients who develop postoperative AKI, in-hospital mortality rate, and 30 and 90 postoperative days events. A sample size of 1265 patients will provide a power of 80% to detect a 4% absolute reduction in the rate of the primary outcome.

CONCLUSIONS

The niMON data will provide evidence to guide the choice of the most appropriate intraoperative blood pressure monitoring strategy.

CLINICAL TRIAL REGISTRATION

Clinical Trial Registration: NCT05496322, registered on the 5th of August 2023.

Correlation among Poincare plot and traditional heart rate variability indices in adults with different risk levels of metabolic syndrome: a cross-sectional approach from Southern India

OBJECTIVES

Heart rate variability (HRV) is an important marker of cardiac autonomic modulation. Metabolic syndrome (MetS) can alter cardiac autonomic modulation, raising the risk of cardiovascular disease (CVD). Poincaré plot analysis (PPA) is a robust scatter plot-based depiction of HRV and carries similar information to the traditional HRV measures. However, no prior studies have examined the relationship between PPA and traditional HRV measures among different risk levels of MetS. We evaluated the association between the Poincare plot and traditional heart rate variability indices among adults with different risk levels of MetS.

METHODS

We measured anthropometric data and collected fasting blood samples to diagnose MetS. The MetS risk was assessed in 223 participants based on the number of MetS components and was classified as control (n=64), pre-MetS (n=49), MetS (n=56), and severe MetS (n=54). We calculated the Poincaré plot (PP) and traditional HRV measures from a 5 min HRV recording.

RESULTS

Besides the traditional HRV measures, we found that various HRV indices of PPA showed significant differences among the groups. The severe MetS group had significantly lower S (total HRV), SD1 (short-term HRV), SD2 (long-term HRV), and higher SD2/SD1. The values of S, SD1, SD2, and SD2/SD1 were significantly correlated with most traditional HRV measures.

CONCLUSIONS

We found gradual changes in HRV patterns as lower parasympathetic and higher sympathetic activity alongside the rising number of MetS components. The HRV indices of PPA integrating the benefits of traditional HRV indices distinguish successfully between different risk levels of MetS and control subjects.

Comparison of noninvasive continuous arterial blood pressure measured by NICAP with arterial line in elderly patients

BACKGROUND

Non-Invasive Continuous Arterial Pressure system (NICAP) allows continuous monitoring, timely detection of hypotension, and avoiding risks from invasive procedures. A previous study showed good comparability of NICAP with arterial line in people with no evidence of cardiovascular disease. Therefore, the goal of this study was to investigate whether NICAP could be accurately applied to elderly patients.

METHODS

In this single-centered observational study, forty-one patients above 65 undergoing elective surgeries requiring artery catheterizations were enrolled from July 17, 2020, to June 25, 2021. Radial artery cannulation and NICAP monitoring were started before anesthesia. Blood pressure during the anesthesia induction and the whole surgery, trend of blood pressure changes, time needed for establishing continuous monitoring, and complications were recorded.

RESULTS

A total of 6751 valid pairs of blood pressure measurements were analyzed. In the Bland-Altman analysis, the arithmetic means for systolic, diastolic, and mean arterial pressure were 2.2, 3.3, and 2.8 mmHg, respectively. NICAP and arterial line correlation coefficients for systolic, diastolic, and mean arterial pressure were 0.49, 0.33, and 0.45, respectively. In the trending analysis, the polar concordance rates at 30 degrees were 70.9% for systolic, 67.7% for diastolic, and 69.3% for mean arterial blood pressure. During the anesthesia induction, the arithmetic means for systolic, diastolic, and mean arterial pressure in the Bland-Altman analysis were 1.7, -0.2, and 0.5 mmHg, respectively. NICAP and arterial line correlation coefficients for systolic, diastolic, and mean arterial pressure were 0.78, 0.61 and 0.75, respectively. No severe complications occurred.

CONCLUSIONS

NICAP has a poor correlation with the arterial line in elderly patients for the whole surgery or during anesthesia induction. Moreover, it showed poor comparability in the detection of blood pressure change trends with arterial lines. Our findings suggest that NICAP might not be sufficiently accurate to be applied clinically in elderly patients with comorbidities. More accurate calibration and iteration are needed.

Performance of the Hypotension Prediction Index With Noninvasive Arterial Pressure Waveforms in Awake Cesarean Delivery Patients Under Spinal Anesthesia

BACKGROUND

Arterial hypotension is common after spinal anesthesia (SA) for cesarean delivery (CD), and to date, there is no definitive method to predict it. The hypotension prediction index (HPI) is an algorithm that uses the arterial waveform to predict early phases of intraoperative hypotension. The aims of this study were to assess the diagnostic ability of HPI working with arterial waveforms detected by ClearSight system in predicting impending hypotension in awake patients, and the agreement of pressure values recorded by ClearSight with conventional noninvasive blood pressure (NIBP) monitoring in patients undergoing CD under SA.

METHODS

In this retrospective analysis of pregnant patients scheduled for elective CD under SA, continuous hemodynamic data measured with the ClearSight monitor until delivery were downloaded from an Edwards Lifesciences HemoSphere platform and analyzed. Receiver operating characteristic (ROC) curves were constructed to evaluate the performance of HPI algorithm working on the ClearSight pressure waveform in predicting hypotensive events, defined as mean arterial pressure (MAP) <65 mm Hg for >1 minute. The sensitivity, specificity, positive predictive value, and negative predictive value were computed at the optimal cutpoint, selected as the value that minimizes the difference between sensitivity and specificity. ClearSight MAP values were compared to NIBP MAP values by linear regression and Bland-Altman analysis corrected for repeated measurements.

RESULTS

Fifty patients undergoing CD were included in the analysis. Hypotension occurred in 23 patients (48%). Among patients experiencing hypotension, the HPI disclosed 71 alerts. The HPI predicted hypotensive events with a sensitivity of 83% (95% confidence interval [CI], 69-97) and specificity of 83% (95% CI, 70-95) at 3 minutes before the event (area under the curve [AUC] 0.913 [95% CI, 0.837-0.99]); with a sensitivity of 97% (95% CI, 92-100) and specificity of 97% (95% CI, 92-100) at 2 minutes before the event (AUC 0.995 [95% CI, 0.979-1.0]); and with a sensitivity of 100% (95% CI, 100-100) and specificity 100% (95% CI, 100-100) 1 minute before the event (AUC 1.0 [95% CI, 1.0-1.0]). A total of 2280 paired NIBP MAP and ClearSight MAP values were assessed. The mean of the differences between the ClearSight and NIBP assessed using Bland-Altman analysis (±standard deviation [SD]; 95% limits of agreement with respective 95% CI) was -0.97 mm Hg (±4.8; -10.5 [-10.8 to -10.1] to 8.5 [8.1-8.8]).

CONCLUSIONS

HPI provides an accurate real time and continuous prediction of impending intraoperative hypotension before its occurrence in awake patients under SA. We found acceptable agreement between ClearSight MAP and NIBP MAP.

Accuracy and precision of continuous non-invasive arterial pressure monitoring in critical care: A systematic review and meta-analysis

OBJECTIVE

To summarize the evidence regarding the accuracy of continuous non-invasive arterial pressure measurements in adult critical care patients.

RESEARCH METHODOLOGY

Medline, EMBASE, and CINAHL were searched for studies that included adult critical care patients reporting the agreement between continuous non-invasive and invasive arterial pressure measurements. The studies were selected and assessed for risk of bias using the Revised Quality Assessment of Diagnostic Accuracy Studies tool by two independent reviewers. The Grading of Recommendations, Assessment, Development and Evaluations approach was used. Pooled estimates of the mean bias and limits of agreement with outer 95% confidence intervals (termed population limits of agreement) were calculated.

RESULTS

Population limits of agreement for systolic blood pressure were wide, spanning from -36.13 mmHg to 28.28 mmHg (18 studies; 785 participants). Accuracy of diastolic blood pressure measurements was highly inconsistent across studies, resulting in imprecise estimates for the population limits of agreement. Population limits of agreement for mean arterial pressure spanned from -39.96 mmHg to 44.36 mmHg (17 studies; 765 participants). The evidence was rated as very low-quality due to very serious concerns about heterogeneity and imprecision.

CONCLUSION

Substantial differences in blood pressure were identified between measurements taken from continuous non-invasive and invasive monitoring devices. Clinicians should consider this broad range of uncertainty if using these devices to inform clinical decision-making in critical care.

Perioperative Continuous Noninvasive Arterial Pressure Monitoring for Neuroendovascular Interventions: Prospective Study for Evaluation of the Vascular Unloading Technique

BACKGROUND

Blood pressure monitoring is crucial during neuroendovascular procedures. Intraoperative hemodynamic instability is associated with complications, which underscores the importance of continuous monitoring. Although direct measurement with an intra-arterial catheter is the gold standard for determining arterial pressure, it is costly, time-consuming, and associated with complications. The novel ClearSight system offers a noninvasive technique for monitoring arterial pressure via a finger cuff. This study compared noninvasive arterial pressure measurements with the gold standard method.

METHODS

Simultaneous recording of noninvasive and invasive arterial pressure was performed in patients undergoing neuroendovascular interventions. Both techniques were compared employing linear regression, Lin's correlation coefficient, Bland-Altman, and error grid analysis.

RESULTS

The study enrolled 24 consecutive patients. The concordance correlation coefficient between both methods was 0.3526 (95% confidence interval [0.3134, 0.3906]) for mean arterial pressure and 0.4680 (95% confidence interval [0.4353, 0.4995]) and for systolic arterial pressure. The mean (SD) of the differences was 0.81 (17.86) mm Hg (95% limits of agreement [-52.52, 54.14]) for mean arterial pressure and 5.38 (14.64) mm Hg (95% limits of agreement [-45.12, 56.08]) for systolic arterial pressure. Error grid analysis demonstrated that the majority of measurements lie in regions with no or low risk for patients (mean arterial pressure, 71.0% and 24.4%; systolic arterial pressure, 59.2% and 25.8%).

CONCLUSIONS

The ClearSight system provided accurate measurements of arterial blood pressure compared with invasive methods and within safe clinical parameters. This method may serve as a safe and reliable alternative for invasive blood pressure monitoring during neuroendovascular procedures.

Monitoring of blood pressure in the perioperatory hypertensive patient

The choice of the type of blood pressure monitoring in patients with uncontrolled hypertension varies depending on the patient's risk due to his previous pathology and cardiovascular risk, as well as the risk of the type of surgical intervention. We must assess the possibility of using new non-invasive monitors that allow optimal control of blood pressure continuously and evaluate the usefulness of new hemodynamic indexes that are still under study.

Development of a Multi-Array Pressure Sensor Module for Radial Artery Pulse Wave Measurement

This study proposes a new structure for a pressure sensor module that can reduce errors caused by measurement position and direction in noninvasive radial artery pulse wave measurement, which is used for physiological monitoring. We have proposed a structure for a multi-array pressure sensor with a hexagonal arrangement and polydimethylsiloxane that easily fits to the structure of the radial artery, and evaluated the characteristics and pulse wave measurement of the developed sensor by finite element method simulation, a push–pull gauge test, and an actual pulse wave measurement experiment. The developed sensor has a measuring area of 17.6 × 17.6 mm² and a modular structure with the analog front end embedded on the printed circuit board. The finite element method simulation shows that the developed sensor responds linearly to external pressure. According to the push–pull gauge test results for each channel, there were differences between the channels caused by the unit sensor characteristics and fabrication process. However, the correction formula can minimize the differences and ensure the linearity, and root-mean-squared error is 0.267 kPa in calibrated output. Although additional experiments and considerations on inter-individual differences are required, the results suggested that the proposed multiarray sensor could be used as a radial arterial pulse wave sensor.

Impact of non-invasive continuous blood pressure monitoring on maternal hypotension during cesarean delivery: a randomized-controlled study

PURPOSE

This study aimed to investigate the efficacy of the ClearSight™ system (Edwards Lifesciences, Irvine, CA) for reducing the incidence of hypotension compared with the traditional oscillometric blood pressure monitoring in cesarean delivery under spinal anesthesia.

METHODS

Forty patients undergoing cesarean delivery under spinal anesthesia were enrolled. The patients were randomly divided into two groups (Control and ClearSight groups). All patients received spinal anesthesia using 0.5% hyperbaric bupivacaine (11.5 mg) and fentanyl (10 µg). Blood pressure was managed with the same protocol using the ClearSight™ system (ClearSight group) and oscillometric blood pressure monitoring (Control group). Furthermore, we compared the accuracy of the ClearSight™ system with the traditional oscillometric monitoring for blood pressure measurement using Bland-Altman, four-quadrant plot, and polar plot analyses.

RESULTS

The incidence of hypotension was significantly lower in the ClearSight group from induction to delivery (45% vs. 0%, p < 0.001) and to the end of surgery (50% vs. 20%, p = 0.049). Intraoperative nausea occurred more frequently in the Control group (45% vs. 10%, p = 0.012). The ClearSight™ system demonstrated acceptable accuracy with a bias of - 4.3 ± 11.7 mmHg throughout the procedure. Four-quadrant analysis revealed an excellent trending ability of the ClearSight™ system with a concordance rate of approximately 95%. In the polar plot analysis, the angular bias and concordance rate were - 13.5° ± 19.0° and 76.9%, respectively.

CONCLUSIONS

The accuracy and trending ability of the ClearSight™ system for blood pressure measurement was clinically acceptable in cesarean delivery under spinal anesthesia, leading to reductions in maternal hypotension and nausea.

Noninvasive Hemodynamic Measurements During Neurosurgical Procedures in Sitting Position

BACKGROUND

Neurosurgical procedures in sitting position need advanced cardiovascular monitoring. Transesophageal echocardiography (TEE) to measure cardiac output (CO)/cardiac index (CI) and stroke volume (SV), and invasive arterial blood pressure measurements for systolic (ABPsys), diastolic (ABPdiast) and mean arterial pressure (MAP) are established monitoring technologies for these kind of procedures. A noninvasive device for continuous monitoring of blood pressure and CO based on a modified Penaz technique (volume-clamp method) was introduced recently. In the present study the noninvasive blood pressure measurements were compared with invasive arterial blood pressure monitoring, and the noninvasive CO monitoring to TEE measurements.

METHODS

Measurements of blood pressure and CO were performed in 35 patients before/after giving a fluid bolus and a change from supine to sitting position, start of surgery, and repositioning from sitting to supine at the end of surgery. Data pairs from the noninvasive device (Nexfin HD) versus arterial line measurements (ABPsys, ABPdiast, MAP) and versus TEE (CO, CI, SV) were compared using Bland-Altman analysis and percentage error.

RESULTS

All parameters compared (CO, CI, SV, ABPsys, ABPdiast, MAP) showed a large bias and wide limits of agreement. Percentage error was above 30% for all parameters except ABPsys.

CONCLUSION

The noninvasive device based on a modified Penaz technique cannot replace arterial blood pressure monitoring or TEE in anesthetized patients undergoing neurosurgery in sitting position.

Continuous Non-Invasive Arterial Pressure Assessment during Surgery to Improve Outcome

Blood pressure (BP) is one of the most important variables evaluated during almost every medical examination. Most national anesthesiology societies recommend BP monitoring at least once every 5 min in anesthetized subjects undergoing surgical procedures. In most cases, BP is monitored non-invasively using oscillometric cuffs. Although the risk of arterial cannulation is not very high, the invasive BP monitoring is usually indicated only in the case of high-risk patients or in complex surgical procedures. However, recent evidence points out that when using intermittent BP monitoring short periods of hypotension may be overlooked. In addition, large datasets have demonstrated that even short periods of low BP (or their cumulative duration) may have a detrimental impact on the development of postoperative outcome including increased risk of acute kidney or myocardial injury development. Recently marketed continuous non-invasive blood pressure monitoring tools may help us to recognize the BP fluctuation without the associated burden of arterial cannulation filling the gap between intermittent non-invasive cuff and continuous invasive arterial pressure. Among others, several novel devices based either on volume clamp/vascular unloading method or on applanation tonometry are nowadays available. Moreover, several near-future smart technologies may lead to better hypotension recognition or even prediction potentially improving our ability to maintain BP stability throughout the anesthesia or surgical procedure. In this review, novel or emerging technologies of non-invasive continuous blood pressure assessment and their potential to improve postoperative outcome are discussed.

Pulse-contour derived cardiac output measurements in morbid obesity: influence of actual, ideal and adjusted bodyweight

The non-invasive Nexfin cardiac output (CO) monitor shows a low level of agreement with the gold standard thermodilution method in morbidly obese patients. Here we investigate whether this disagreement is related to excessive bodyweight, and can be improved when bodyweight derivatives are used instead. We performed offline analyses of cardiac output recordings of patient data previously used and partly published in an earlier study by our group. In 30 morbidly obese patients (BMI > 35 kg/m²) undergoing laparoscopic gastric bypass, cardiac output was simultaneously determined with PiCCO thermodilution and Nexfin pulse-contour method. We investigated if agreement of Nexfin-derived CO with thermodilution CO improved when ideal and adjusted—instead of actual- bodyweight were used as input to the Nexfin. Bodyweight correlated with the difference between Nexfin-derived and thermodilution-derived CO (r = −0.56; p = 0.001). Bland Altman analysis of agreement between Nexfin and thermodilution-derived CO revealed a bias of 0.4 ± 1.6 with limits of agreement (LOA) from −2.6 to 3.5 L min when actual bodyweight was used. Bias was −0.6 ± 1.4 and LOA ranged from −3.4 to 2.3 L min when ideal bodyweight was used. With adjusted bodyweight, bias improved to 0.04 ± 1.4 with LOA from −2.8 to 2.9 L min. Our study shows that agreement of the Nexfin-derived with invasive CO measurements in morbidly obese patients is influenced by body weight, suggesting that Nexfin CO measurements in patients with a BMI above 35 kg/m² should be interpreted with caution. Using adjusted body weight in the Nexfin CO-trek algorithm reduced the bias.

Update on Finger-Application-Type Noninvasive Continuous Hemodynamic Monitors (CNAP and ccNexfin): Physical Principles, Validation, and Clinical Use

The CNAP HD Monitor (CNSystems, Graz, Austria) and the ccNexfin (The ClearSight System: Edwards Lifesciences Corporation, Irvine, CA) are continuous, noninvasive blood pressure monitors using a finger-application device. These devices show a promising ability to allow for rapid detection of hemodynamic derangement when compared with oscillometry. The accuracy and precision of these devices as blood pressure monitors has been evaluated when compared with intra-arterial catheters. Additionally, they can be used to measure beat-to-beat cardiac output (CO). As CO monitors, they are capable of trending changes in CO when compared with a transpulmonary thermodilution monitor. Difficulty with use in critically ill and awake patients has been encountered because of altered microvascular physiology and patient movement. The principles of operation and clinical validation of these devices are presented. The clinicians who are interested in using these devices in their clinical setting should be aware of the relatively large bias and CIs in the hemodynamic measurements.

Comparison of the non-invasive Nexfin® monitor with conventional methods for the measurement of arterial blood pressure in moderate risk orthopaedic surgery patients

Objective

Continuous invasive arterial blood pressure (IBP) monitoring remains the gold standard for BP measurement, but traditional oscillometric non-invasive intermittent pressure (NIBP) measurement is used in most low-to-moderate risk procedures. This study compared non-invasive continuous arterial BP measurement using a Nexfin® monitor with NIBP and IBP monitors.

Methods

This was a single-centre, prospective, pilot study in patients scheduled for elective orthopaedic surgery. Systolic BP, diastolic BP and mean arterial blood pressure (MAP) were measured by Nexfin®, IBP and NIBP at five intraoperative time-points. Pearson correlation coefficients, Bland–Altman plots and trending ability of Nexfin® measurements were used as criteria for success in the investigation of measurement reliability.

Results

A total of 20 patients were enrolled in the study. For MAP, there was a sufficient correlation between IBP/Nexfin® (Pearson = 0.75), which was better than the correlation between IBP/NIBP (Pearson = 0.70). Bland–Altman analysis of the data showed that compared with IBP, there was a higher percentage error for MAP_NIBP (30%) compared with MAP_Nexfin® (27%). Nexfin® and NIBP underestimated systolic BP; NIBP also underestimated diastolic BP and MAP. Trending ability for MAP_Nexfin® and MAP_NIBP were comparable to IBP.

Conclusion

Non-invasive BP measurement with Nexfin® was comparable with IBP and tended to be more precise than NIBP.

Perioperative hemodynamic optimization using the photoplethysmography in colorectal surgery (the PANEX3 trial): study protocol for a randomized controlled trial

Background

Photoplethysmography with a digital sensor (ClearSight, Edwards Lifesciences, Irvine, CA, USA) connected to a dedicated monitor (EV 1000, Edwards Lifesciences) was recently proposed for use in performing hemodynamic optimization during surgery. The objective of this study is to evaluate the effect of photoplethysmography on the incidence of postoperative complications compared with the conventional hemodynamic algorithm, which uses mean arterial pressure.

Methods/design

The hemodynamic optimization using photoplethysmography (PANEX3) trial is a monocentric, randomized, single-blind, controlled, two parallel arm, superiority trial, randomizing 160 patients with an intermediate risk of postoperative complications after colorectal surgery. Informed consent will be obtained from all participants. The hemodynamic optimization is conducted using a specified hemodynamic algorithm either with photoplethysmography (the photoplethysmography group) or with conventional mean arterial pressure (the control group). The anesthesiologist performed a 1:1 randomization the day before surgery using a scratch card, which is available 24/7. The randomization sequence is generated using permutated blocks. Both the patients and surgeons are blinded to the allocation group. The primary outcome is the incidence of at least one postoperative complication during the 30 days following surgery. Two independent experts, who were blinded to the group allocations, validate the complication for each patient using an a priori classification. The secondary outcomes are to study the total number of postoperative complications, the real length of hospital stays, and the postoperative mortality between each group.

Discussion

The PANEX3 trial is the first randomized controlled study conducted to investigate whether perioperative hemodynamic optimization using photoplethysmography during colorectal surgery could decrease the incidence of patients having at least one postoperative complication.

Trial Registration

ClinicalTrials.gov Identifier: NCT02343601

Rigorous anaesthesia management protocol for patients with intracranial arterial stenosis: a prospective controlled-cohort study

OBJECTIVES

Reducing variability is integral in quality management. As part of the ongoing Encephaloduroarteriosynangiosis Revascularisation for Symptomatic Intracranial Arterial Stenosis (ERSIAS) trial, we developed a strict anaesthesia protocol to minimise fluctuations in patient parameters affecting cerebral perfusion. We hypothesise that this protocol reduces the intraoperative variability of targeted monitored parameters compared to standard management.

DESIGN

Prospective cohort study of patients undergoing encephaloduroarteriosynangiosis surgery versus standard neurovascular interventions. Patients with ERSIAS had strict perioperative management that included normocapnia and intentional hypertension. Control patients received regular anaesthetic standard of care. Minute-by-minute intraoperative vitals were electronically collected. Heterogeneity of variance tests were used to compare variance across groups. Mixed-model regression analysis was performed to establish the effects of treatment group on the monitored parameters.

SETTING

Tertiary care centre.

PARTICIPANTS

24 participants: 12 cases (53.8 years ± 16.7 years; 10 females) and 12 controls (51.3 years ± 15.2 years; 10 females). Adults aged 30-80 years, with transient ischaemic attack or non-disabling stroke (modified Rankin Scale <3) attributed to 70-99% intracranial stenosis of the carotid or middle cerebral artery, were considered for enrolment. Controls were matched according to age, gender and history of neurovascular intervention.

MAIN OUTCOME MEASURES

Variability of heart rate, mean arterial blood pressure (MAP), systolic blood pressure and end tidal CO2 (ETCO2) throughout surgical duration.

RESULTS

There were significant reductions in the intraoperative MAP SD (4.26 vs 10.23 mm Hg; p=0.007) and ETCO2 SD (0.94 vs 1.26 mm Hg; p=0.05) between the ERSIAS and control groups. Median MAP and ETCO2 in the ERSIAS group were higher (98 mm Hg, IQR 23 vs 75 mm Hg, IQR 15; p<0.001, and 38 mm Hg, IQR 4 vs 32 mm Hg, IQR 3; p<0.001, respectively).

CONCLUSIONS

The ERSIAS anaesthesia protocol successfully reduced intraoperative fluctuations of MAP and ETCO2. The protocol also achieved normocarbia and the intended hypertension.

TRIAL REGISTRATION NUMBER

NCT01819597; Pre-results.

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

Background

The 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.

Methods

Three 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.

Results

Both 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.

Conclusion

In 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 registration

ACTRN12612001014842

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-015-0131-8) contains supplementary material, which is available to authorized users.

Non-invasive measurements of pulse pressure variation and stroke volume variation in anesthetized patients using the Nexfin blood pressure monitor

Nexfin beat-to-beat arterial blood pressure monitoring enables continuous assessment of hemodynamic indices like cardiac index (CI), pulse pressure variation (PPV) and stroke volume variation (SVV) in the perioperative setting. In this study we investigated whether Nexfin adequately reflects alterations in these hemodynamic parameters during a provoked fluid shift in anesthetized and mechanically ventilated patients. The study included 54 patients undergoing non-thoracic surgery with positive pressure mechanical ventilation. The provoked fluid shift comprised 15° Trendelenburg positioning, and fluid responsiveness was defined as a concomitant increase in stroke volume (SV) >10 %. Nexfin blood pressure measurements were performed during supine steady state, Trendelenburg and supine repositioning. Hemodynamic parameters included arterial blood pressure (MAP), CI, PPV and SVV. Trendelenburg positioning did not affect MAP or CI, but induced a decrease in PPV and SVV by 3.3 ± 2.8 and 3.4 ± 2.7 %, respectively. PPV and SVV returned back to baseline values after repositioning of the patient to baseline. Bland–Altman analysis of SVV and PPV showed a bias of −0.3 ± 3.0 % with limits of agreement ranging from −5.6 to 6.2 %. The SVV was more superior in predicting fluid responsiveness (AUC 0.728) than the PVV (AUC 0.636), respectively. The median bias between PPV and SVV was different for patients younger [−1.5 % (−3 to 0)] or older [+2 % (0–4.75)] than 55 years (P < 0.001), while there were no gender differences in the bias between PPV and SVV. The Nexfin monitor adequately reflects alterations in PPV and SVV during a provoked fluid shift, but the level of agreement between PPV and SVV was low. The SVV tended to be superior over PPV or Ea_dyn in predicting fluid responsiveness in our population.

Non-invasive assessment of cardiac hemodynamics in patients with advanced cancer and with chronic heart failure: a pilot feasibility study

INTRODUCTION

Relationships between cardiac pressure and volume have been suggested as markers of cardiac contractility; parameters include stroke work and the maximal rate of pressure rise during isovolumic contraction (dP/dtmax). Patients with cancer often display dyspnea and fatigue. These are also frequent symptoms in patients with chronic heart failure (HF). The reasons for similar symptoms in cancer patients are unknown. Using the novel Nexfin Finapres technique, we sought to assess measures of cardiac performance in patients with cancer and compare these values with those from control subjects and patients with chronic HF.

MATERIAL AND METHODS

We prospectively studied 98 patients (control n = 18, chronic HF n = 37, advanced pancreatic or colorectal cancer n = 43) and assessed blood pressure (BP), stroke volume (SV), cardiac output (CO), and dP/dtmax at rest.

RESULTS

All parameters of interest could be assessed using the Nexfin Finapres technique with SV and CO being significantly higher in patients with cancer than in controls (both p < 0.05). The SV was significantly higher in patients with chronic HF than in controls (p < 0.05). In patients with cancer, SV correlated with age (r = -0.45, p < 0.01) and body weight (r = +0.55, p = 0.0001). In chronic HF, SV declined with increasing age (r = -0.49, p < 0.01); in control subjects, SV increased with increasing body weight (r = +0.57, p = 0.01).

CONCLUSIONS

Patients with cancer tended to display elevated BP, CO, SV, and dP/dtmax as compared to control subjects and patients with HF. These findings may reveal an elevated risk for cardiovascular diseases in this group.

Noninvasive continuous hemodynamic monitoring

Monitoring of continuous blood pressure and cardiac output is important to prevent hypoperfusion and to guide fluid administration, but only few patients receive such monitoring due to the invasive nature of most of the methods presently available. Noninvasive blood pressure can be determined continuously using finger cuff technology and cardiac output is easily obtained using a pulse contour method. In this way completely noninvasive continuous blood pressure and cardiac output are available for clinical use in all patients that would otherwise not be monitored. Developments and state of art in hemodynamic monitoring are reviewed here, with a focus on noninvasive continuous hemodynamic monitoring form the finger.