Radial artery applanation tonometry for continuous noninvasive arterial blood pressure monitoring in the cardiac intensive care unit

The Use of Non-Invasive Continuous Blood Pressure Measuring (ClearSight®) during Central Neuraxial Anaesthesia for Caesarean Section—A Retrospective Validation Study

The close monitoring of blood pressure during a caesarean section performed under central neuraxial anaesthesia should be the standard of safe anaesthesia. As classical oscillometric and invasive blood pressure measuring have intrinsic disadvantages, we investigated a novel, non-invasive technique for continuous blood pressure measuring. Methods: In this monocentric, retrospective data analysis, the reliability of continuous non-invasive blood pressure measuring using ClearSight^® (Edwards Lifesciences Corporation) is validated in 31 women undergoing central neuraxial anaesthesia for caesarean section. In addition, patients and professionals evaluated ClearSight^® through questioning. Results: 139 measurements from 11 patients were included in the final analysis. Employing Bland–Altman analyses, we identified a bias of −10.8 mmHg for systolic, of −0.45 mmHg for diastolic and of +0.68 mmHg for mean arterial blood pressure measurements. Pooling all paired measurements resulted in a Pearson correlation coefficient of 0.7 for systolic, of 0.67 for diastolic and of 0.75 for mean arterial blood pressure. Compensating the interindividual differences in linear regressions of the paired measurements provided improved correlation coefficients of 0.73 for systolic, of 0.9 for diastolic and of 0.89 for mean arterial blood pressure measurements. Discussion: Diastolic and mean arterial blood pressure are within an acceptable range of deviation from the reference method, according to the Association for the Advancement of Medical Instrumentation (AAMI) in the patient collective under study. Both patients and professionals prefer ClearSight^® to oscillometric blood pressure measurement in regard of comfort and handling.

Comparison of the Effect of Heparinized Normal Saline Solution Versus Saline Solutions in Arterial and Central Venous Catheters on Complete Blood Count After Cardiac Surgery

Background

Heparinized and saline solutions can prevent clot formation in arterial and central venous catheters. However, heparin can decrease the platelet count and induce thrombocytopenia. Patients undergoing cardiac surgeries are more likely to develop heparin-induced thrombocytopenia.

Objectives

This study aimed to investigate the effect of heparinized and saline solutions of arterial and central venous catheters on complete blood count (CBC) after cardiac surgery.

Methods

This randomized controlled trial was conducted on 100 participants. All subjects underwent cardiac surgery at Rajaie Cardiovascular, Medical, and Research Center, Tehran, Iran. Patients were randomly divided into two groups intervention (A) for whom heparinized normal saline solution was used to maintain central arterial and venous catheters, and control (B) for whom normal saline solution was used. The CBC of subjects was monitored for three days (before surgery and the first and second days after surgery).

Results

In the present study, there were no significant differences between CBC, white blood cell differential count, prothrombin time, partial thromboplastin time (PTT), and international normalized ratio in groups A and B. However, we found significant differences in platelet count (P = 0.049), red blood cell count (P = 0.0001), hemoglobin (P = 0.0001), and hematocrit (P = 0.0001) between before surgery and the second day after surgery in group A. Platelet count (P = 0.027) and PTT (P = 0.0001) before and after surgery were significantly different in group B.

Conclusions

According to the results of this study, normal saline solution catheters have fewer side effects and can be a suitable replacement for heparinized catheters.

Contemporary Review of Hemodynamic Monitoring in the Critical Care Setting

Hemodynamic assessment remains the most valuable adjunct to physical examination and laboratory assessment in the diagnosis and management of shock. Through the years, multiple modalities to measure and trend hemodynamic indices have evolved with varying degrees of invasiveness. Pulmonary artery catheter (PAC) has long been considered the gold standard of hemodynamic assessment in critically ill patients and in recent years has been shown to improve clinical outcomes among patients in cardiogenic shock. The invasive nature of PAC is often cited as its major limitation and has encouraged development of less invasive technologies. In this review, the authors summarize the literature on the mechanism and validation of several minimally invasive and noninvasive modalities available in the contemporary intensive care unit. They also provide an update on the use of focused bedside echocardiography.

Continuous Noninvasive Blood Pressure Monitoring of Beat-By-Beat Blood Pressure and Heart Rate Using Caretaker Compared With Invasive Arterial Catheter in the Intensive Care Unit

OBJECTIVE

To examine the accuracy of noninvasively-derived peripheral arterial blood pressure (BP) by the Caretaker device (CT) against invasively measured arterial BP and the fidelity of heart rate variability by CT compared with electrocardiogram (ECG)-derived data.

DESIGN

Prospective cohort study.

PARTICIPANTS

Adult surgical and trauma patients admitted to the intensive care unit.

SETTING

Academic tertiary care medical center.

INTERVENTIONS

In a prospective manner, beat-by-beat BP by CT was recorded simultaneously with invasive arterial BP measured in patients in the intensive care unit. Invasive arterial BPs were compared with those obtained by the CT system. All comparisons among the CT data, arterial catheter data, and ECG data were postprocessed.

MEASUREMENTS AND MAIN RESULTS

From 37 enrolled patients, 34 were included with satisfactory data that overlapped between arterial catheter and CT. A total of 87,757 comparative data points were obtained for the 40-minute time window comparisons of the 34 patients, spanning approximately 22.5 hours in total. Systolic BP and diastolic BP correlations (Pearson coefficient), as well as the mean difference (standard deviation), were 0.92 and -0.36 (7.57) mmHg and 0.83 and -2.11 (6.00) mmHg, respectively. The overall interbeat correlation was 0.99, with the mean difference between interbeats obtained with the arterial BP and the CT of -0.056 ms (6.0).

CONCLUSIONS

This study validated the noninvasive tracking of BP using the CT device, and the pulse decomposition analysis approach is possible within the guidelines of the standard.

A physiologically realistic virtual patient database for the study of arterial haemodynamics

This study creates a physiologically realistic virtual patient database (VPD), representing the human arterial system, for the primary purpose of studying the effects of arterial disease on haemodynamics. A low dimensional representation of an anatomically detailed arterial network is outlined, and a physiologically realistic posterior distribution for its parameters constructed through the use of a Bayesian approach. This approach combines both physiological/geometrical constraints and the available measurements reported in the literature. A key contribution of this work is to present a framework for including all such available information for the creation of virtual patients (VPs). The Markov Chain Monte Carlo (MCMC) method is used to sample random VPs from this posterior distribution, and the pressure and flow-rate profiles associated with each VP computed through a physics based model of pulse wave propagation. This combination of the arterial network parameters (representing a virtual patient) and the haemodynamics waveforms of pressure and flow-rates at various locations (representing functional response and potential measurements that can be acquired in the virtual patient) makes up the VPD. While 75,000 VPs are sampled from the posterior distribution, 10,000 are discarded as the initial burn-in period of the MCMC sampler. A further 12,857 VPs are subsequently removed due to the presence of negative average flow-rate, reducing the VPD to 52,143. Due to undesirable behaviour observed in some VPs-asymmetric under- and over-damped pressure and flow-rate profiles in left and right sides of the arterial system-a filter is proposed to remove VPs showing such behaviour. Post application of the filter, the VPD has 28,868 subjects. It is shown that the methodology is appropriate by comparing the VPD statistics to those reported in literature across real populations. Generally, a good agreement between the two is found while respecting physiological/geometrical constraints.

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.

Nursing care for patient in post operatory heart surgery in the Intensive Care Unit

OBJECTIVE

To investigate the critical nodes related to nursing care for patients in the postoperative period of cardiac surgery.

METHODS

Exploratory study with a qualitative approach. Data collected through semi-structured interviews with 27 members of the nursing team working in the Intensive Care Unit. Material submitted to thematic analysis.

RESULTS

Three categories emerged: Flaws in the professional qualification for patient care in the postoperative period of cardiac surgery; Team challenges concerning specific patient care in the postoperative period of cardiac surgery; and (dis) organization of work in the Intensive Care Unit and its impact on nursing care for patients in the postoperative period of cardiac surgery.

FINAL CONSIDERATIONS

Given the identification of the critical nodes, the professionals presented suggestions to overcome daily difficulties: investments in strategies for Permanent Education in Health; creation of tools to guide patient assistance in the postoperative of cardiac surgery; and provision of adequate human resources.

Noninvasive estimation of aortic hemodynamics and cardiac contractility using machine learning

Cardiac and aortic characteristics are crucial for cardiovascular disease detection. However, noninvasive estimation of aortic hemodynamics and cardiac contractility is still challenging. This paper investigated the potential of estimating aortic systolic pressure (aSBP), cardiac output (CO), and end-systolic elastance (E_es) from cuff-pressure and pulse wave velocity (PWV) using regression analysis. The importance of incorporating ejection fraction (EF) as additional input for estimating E_es was also assessed. The models, including Random Forest, Support Vector Regressor, Ridge, Gradient Boosting, were trained/validated using synthetic data (n = 4,018) from an in-silico model. When cuff-pressure and PWV were used as inputs, the normalized-RMSEs/correlations for aSBP, CO, and E_es (best-performing models) were 3.36 ± 0.74%/0.99, 7.60 ± 0.68%/0.96, and 16.96 ± 0.64%/0.37, respectively. Using EF as additional input for estimating E_es significantly improved the predictions (7.00 ± 0.78%/0.92). Results showed that the use of noninvasive pressure measurements allows estimating aSBP and CO with acceptable accuracy. In contrast, E_es cannot be predicted from pressure signals alone. Addition of the EF information greatly improves the estimated E_es. Accuracy of the model-derived aSBP compared to in-vivo aSBP (n = 783) was very satisfactory (5.26 ± 2.30%/0.97). Future in-vivo evaluation of CO and E_es estimations remains to be conducted. This novel methodology has potential to improve the noninvasive monitoring of aortic hemodynamics and cardiac contractility.

Noninvasive continuous blood pressure monitoring using microelectromechanical system technology

BACKGROUND

Continuous blood pressure monitoring is essential in the management of patients in critical conditions, as well as those under anesthesia. However, continuous blood pressure monitoring requires insertion of a catheter into the radial artery. Thus, continuous noninvasive arterial blood pressure monitoring would be ideal.

PARTICIPANTS AND METHODS

We designed and built a continuous noninvasive arterial blood pressure monitoring device with a pressure sensor diaphragm using microelectromechanical system technology, a square with 4 mm sides that were 0.4 mm thick. Comparisons between a continuous noninvasive arterial blood pressure monitoring device and a sphygmomanometer were carried out on 92 volunteers, and comparisons between noninvasive and invasive blood pressure monitoring were performed on three patients perioperatively at Fukushima Medical University Hospital.

RESULTS

In the comparisons of arterial blood pressure measurements between a sphygmomanometer and our device, the differences became gradually greater over time after starting continuous monitoring in conscious participants. In the comparisons of arterial blood pressure measurements between the invasive and noninvasive methods in unconscious subjects under general anesthesia, the results of noninvasive monitoring were consistent with those of invasive arterial blood pressure monitoring.

CONCLUSION

Continuous noninvasive arterial monitoring with a pressure sensor diaphragm using microelectromechanical system technology is a possible alternative to conventional invasive arterial pressure monitoring by an arterial catheter.

Development and clinical validation of a non-invasive, beat-to-beat blood pressure monitoring device, compared to invasive blood pressure monitoring during coronary angiography

Objective

To develop and test a beat-to-beat blood pressure monitoring device during coronary angiography, and compare it with invasive blood pressure monitoring.

Methods

Twenty-eight patients with an indication for hemodynamic study were selected for this investigation, and kept in supine position. Before starting the coronary angiography, they were instructed about the use of the left radial bracelet for beat-to-beat blood pressure monitoring.

Results

There was a significant difference between the time required for the catheterization laboratory team to acquire the first invasive blood pressure reading and the time to obtain the first beat-to-beat reading (11.1±5.1 and 1.5±1.8, respectively; p<0.0001). The intraclass correlation coefficients (95%CI) of systolic and diastolic blood pressures were 0.897 (0.780-0.952) and 0.876 (0.734-0.942), indicating good reproducibility.

Conclusion

This study showed the process to develop a beat-to-beat blood pressure monitoring device. When compared to invasive blood pressure monitoring, there were no significant differences between the two methods. This technique may play a promising coadjuvant role when combined with invasive monitoring during coronary angiography procedures.

Journal of clinical monitoring and computing end of year summary 2018: hemodynamic monitoring and management

Hemodynamic management is a mainstay of patient care in the operating room and intensive care unit (ICU). In order to optimize patient treatment, researchers investigate monitoring technologies, cardiovascular (patho-) physiology, and hemodynamic treatment strategies. The Journal of Clinical Monitoring and Computing (JCMC) is a well-established and recognized platform for publishing research in this field. In this review, we highlight recent advancements and summarize selected papers published in the JCMC in 2018 related to hemodynamic monitoring and management.

A comparison of heparinised and non-heparinised normal saline solutions for maintaining the patency of arterial pressure measurement cannulae after heart surgery

Background

Heparinized solution (HS) use for the maintenance of arterial cannulas has been associated with coagulation disorders and has not been conclusively shown to confer additional benefits over normal saline (NS) alone. We tested the hypothesis that in adult patients admitted to the cardiac ICU (T0) after cardiac surgery, HS arterial cannulas might be independently associated with increased heparin-induced coagulation disorders and might not be superior to NS arterial cannulas in reducing arterial cannula occlusion.

Methods

In this cohort study, 170 patients who received NS arterial cannulas during the period from T0 to ICU discharge were included in this study from June 1, 2017, to May 1, 2018 (NS group). There were 2930 patients who used HS (2.5 U/ml) arterial cannulas from January 1, 2015, to December 31, 2016 (heparin group). To address indicated biases, we derived a propensity score that predicted the functions of NS and HS in the patency of arterial cannulas.

Results

There were 296 patients (148 in the NS group and 148 in the heparin group) with similar risk profiles in the propensity-score matched cohorts. In the propensity-matched patients, the duration of arterial cannulas (P = 0.4) and arterial cannula occlusion (P = 0.5) showed no differences between the NS and heparin groups. However, the heparin group had a significantly increased activated clotting time (P < 0.05), activated partial thromboplastin time (P = 0.01) and allogeneic red blood cell utilization (3.4% vs 10.8%, P < 0.05). Compared with the NS group, the heparin group had more drainage from chest tubes from T0 to T48 (10.6 ± 9.4 ml/kg vs 13.0 ± 7.22 ml/kg, P < 0.05) and had more allogeneic red blood cells transfused (0.1 ± 0.4 U vs 0.4 ± 1.1 U, P < 0.05).

Conclusion

Based on the results of our study, the addition of heparin to normal saline for flushing arterial pressure monitoring cannulae did not reduce the incidence of catheter thrombosis and result in a very small but statically significant in increase in activated clotting time and activated partial thromboplastin time.

Improving Perioperative Outcomes Through Minimally Invasive and Non-invasive Hemodynamic Monitoring Techniques

An increasing number of patients require precise intraoperative hemodynamic monitoring due to aging and comorbidities. To prevent undesirable outcomes from intraoperative hypotension or hypoperfusion, appropriate threshold settings are required. These setting can vary widely from patient to patient. Goal-directed therapy techniques allow for flow monitoring as the standard for perioperative fluid management. Based on the concept of personalized medicine, individual assessment and treatment are more advantageous than conventional or uniform interventions. The recent development of minimally and noninvasive monitoring devices make it possible to apply detailed control, tracking, and observation of broad patient populations, all while reducing adverse complications. In this manuscript, we review the monitoring features of each device, together with possible advantages and disadvantages of their use in optimizing patient hemodynamic management.

Comparison of a pressure-sensing sheath and radial arterial line for intraoperative blood pressure monitoring in neurointerventional procedures

Purpose

The efficiency of neuroendovascular procedures may partly depend on the time devoted to placement of a radial arterial line (RAL) for intraoperative blood pressure monitoring. An alternative approach is to use a pressure-sensing sheath (PSS) that serves to provide invasive blood pressure monitoring without requiring a separate procedure for placement. We compared the use of a RAL versus PSS and assessed procedure time, anesthetist and patient satisfaction, and cost.

Methods

We performed a single-center, prospective, blockwise, comparative trial of procedure start time using traditional RAL placement versus the EndoPhys PSS for invasive blood pressure monitoring. Endpoints included time from room arrival to groin puncture, patient and anesthetist satisfaction ratings, and costs associated with RAL placement.

Results

Twenty patients were enrolled in the PSS+RAL arm and 20 in the PSS-alone arm. Mean time from arrival in the room until groin puncture was 61.9±14.0 min in the RAL group and 51.2±10.8 min in the PSS-alone group (P=0.01; difference=10.7 min). Patients in the PSS-alone group reported less pain than those in the RAL group. Furthermore, anesthetists reported accurate blood pressure in the PSS group. The average cost estimate of RAL placement was US$774.70, with a range of US$743 to US$1171.

Conclusions

Placement of a RAL at the start of the neuroendovascular procedures resulted in increased delays to procedure start time and more patient-reported pain compared with the PSS, which may offer a more efficient means of blood pressure monitoring for neurointerventional procedures.

Clinical trial registration

NCT03239847.

Noninvasive BP Monitoring in the Critically Ill: Time to Abandon the Arterial Catheter?

Although its reliability is often questioned, noninvasive BP (NIBP)-monitoring with an oscillometric arm cuff is widely used, even in critically ill patients in shock. When correctly implemented, modern arm NIBP devices can provide accurate and precise measurements of mean BP, as well as clinically meaningful information such as identification of hypotension and hypertension and monitoring of patient response to therapy. Even in specific circumstances such as arrhythmia, hypotension, vasopressor infusion, and possibly in obese patients, arm NIBP may be useful, contrary to widespread belief. Hence, postponing the arterial catheter insertion pending the initiation of more urgent diagnostic and therapeutic measures could be a suitable strategy. Given the arterial catheter-related burden, fully managing critically ill patients without any arterial catheter may also be an option. Indeed, the benefit that patients may experience from an arterial catheter has been questioned in studies failing to show that its use reduces mortality. However, randomized controlled trials to confirm that NIBP can safely fully replace the arterial catheter have yet to be performed. In addition to intermittent measurements, continuous NIBP monitoring is a booming field, as illustrated by the release onto the market of user-friendly devices, based on digital volume clamp and applanation tonometry. Although the imperfect accuracy and precision of these devices would probably benefit from technical refinements, their good ability to track, in real time, the direction of changes in BP is an undeniable asset. Their drawbacks and advantages and whether these devices are currently ready to use in the critically ill patient are discussed in this review.

Computational study to investigate effect of tonometer geometry and patient-specific variability on radial artery tonometry

Tonometry-based devices are valuable method for vascular function assessment and for measurement of blood pressure. However current design and calibration methods rely on simple models, neglecting key geometrical features, and anthropometric and property variability among patients. Understanding impact of these influences on tonometer measurement is thus essential for improving outcomes of current devices, and for proposing improved design. Towards this goal, we present a realistic computational model for tissue-device interaction using complete wrist section with hyperelastic material and frictional contact. Three different tonometry geometries were considered including a new design, and patient-specific influences incorporated via anthropometric and age-dependent tissue stiffness variations. The results indicated that the new design showed stable surface contact stress with minimum influence of the parameters analyzed. The computational predictions were validated with experimental data from a prototype based on the new design. Finally, we showed that the underlying mechanics of vascular unloading in tonometry to be fundamentally different from that of oscillatory method. Due to directional loading in tonometry, pulse amplitude maxima was observed to occur at a significantly lower compression level (around 31%) than previously reported, which can impact blood pressure calibration approaches based on maximum pulse pressure recordings.

Uncertainty Quantification in a Patient-Specific One-Dimensional Arterial Network Model: EnKF-Based Inflow Estimator

Successful clinical use of patient-specific models for cardiovascular dynamics depends on the reliability of the model output in the presence of input uncertainties. For 1D fluid dynamics models of arterial networks, input uncertainties associated with the model output are related to the specification of vessel and network geometry, parameters within the fluid and wall equations, and parameters used to specify inlet and outlet boundary conditions. This study investigates how uncertainty in the flow profile applied at the inlet boundary of a 1D model affects area and pressure predictions at the center of a single vessel. More specifically, this study develops an iterative scheme based on the ensemble Kalman filter (EnKF) to estimate the temporal inflow profile from a prior distribution of curves. The EnKF-based inflow estimator provides a measure of uncertainty in the size and shape of the estimated inflow, which is propagated through the model to determine the corresponding uncertainty in model predictions of area and pressure. Model predictions are compared to ex vivo area and blood pressure measurements in the ascending aorta, the carotid artery, and the femoral artery of a healthy male Merino sheep. Results discuss dynamics obtained using a linear and a nonlinear viscoelastic wall model.

Is applanation tonometry a reliable method for monitoring blood pressure in morbidly obese patients undergoing bariatric surgery?

BACKGROUND

The aim of this study was to evaluate the validity of non-invasive continuous BP measurement by applanation tonometry in morbidly obese patients undergoing bariatric surgery.

METHODS

Arterial blood pressure (AP) was recorded intraoperatively both by applanation tonometry (AT) (T-Line 200pro, Tensys Medical(®), USA) and an arterial line (AL) after radial cannulation in obese patients undergoing bariatric surgery. Discrepancies between the two methods were assessed as bias, limits of agreement and percentage error. Mean, systolic, and diastolic arterial pressures were assessed (MAP, SAP, DAP respectively). Trending ability was assessed by concordance based on four-quadrant plotting.

RESULTS

Mean (sd) BMI of the 28 patients was 49.4 (9.7 kg m(-2)). A total of 201 907 time points were available for analysis. Bias for MAPAT compared with MAPAL was +3.97 mm Hg (SAPAT +3.45 mm Hg; DAPAT +3.66 mm Hg) with limits of agreement for MAPAT of -14.47 and +22.41 mm Hg (SAPAT -22.0 and +28.9 mm Hg; DAPAT -15.7 and +23.1 mm Hg). Percentage error for MAPAT was 23.5% (23.4% for SAPAT; 30.5% for DAPAT). Trending ability for MAP, SAP, and DAP revealed a concordance of 0.74, 0.72, and 0.71, respectively.

CONCLUSIONS

Continuous BP assessment by applanation tonometry is feasible in morbidly obese patients undergoing bariatric surgery. However, despite a low mean difference, 95% limits of agreement and trending ability indicate that the technology needs to be improved further, before being recommended for routine use in this group of patients.

Avoiding Heparinization of Arterial Line and Maintaining Acceptable Arterial Waveform After Cardiac Surgery: A Randomized Clinical Trial

Background:

Invasive and continuous blood pressure (BP) monitoring is crucial after cardiac surgery. Accuracy of BP measurement mostly depends on patency of arterial catheter and acceptable waveform. Heparinized saline flush usually used for this purpose may be accompanied by potential heparin adverse effects.

Objectives:

The aim of this study was to compare heparinized and non-heparinized saline flush to maintain acceptable arterial waveform after cardiac surgery.

Materials and Methods:

In a double blind randomized trial study, 100 patients undergoing elective cardiac surgery were randomized to using heparinized (n = 50) or non-heparinized (normal) saline flush (n = 50) to maintain patency of arterial catheter after operation. Indwelling arterial catheters were checked daily for acceptable arterial waveform for three days as primary outcome measures.

Results:

Frequency of acceptable arterial waveform ranged from 66% to 80%, in first, second and third postoperative days. There were no statistically significant differences between heparinized and non-heparinized saline groups regarding acceptable arterial waveforms in all the three postoperative days (all P values > 0.05).

Conclusions:

Using non-heparinized normal saline is suitable to maintain acceptable arterial waveform for short-term (three days) after adult cardiac surgery considering potential adverse effects of heparin.