Predictive haemodynamic monitoring in low/intermediate-risk surgery: The right tool, in the right context.

Accuracy and precision of access recirculation measurements by the hemodynamic recirculation monitor

Advanced haemodynamic monitoring has been recommended for use in high-risk surgeries and high-risk patients undergoing surgery. This study aims to assess the current practices of haemodynamic monitoring in high-risk surgical patients among Malaysian anaesthesiologists. This is a cross-sectional survey among Malaysian anaesthesiologists, following approval from the institution's Medical Research Ethics Committee and the National Medical Research Register. The survey utilised a questionnaire developed by Cannesson et al. to gather demographic data, practice information, and haemodynamic monitoring practices. Statistical analysis was performed using SPSS, and results were presented as the mean, median, or frequency as appropriate. A total of 366 participants responded to the questionnaire, and 2 dropped out due to an incomplete form. This study found differences in the frequency of haemodynamic optimisation and monitoring techniques used in different healthcare settings. Written protocols or statements concerning haemodynamic management in high-risk surgical cases were only available to 15.7% of participants in the institution. The overall utilisation rate of cardiac output monitoring was found to be 31.1%, with a significant majority of the usage observed in university hospitals (p < 0.001). Central venous pressure was more commonly used in university hospitals and private hospitals compared to public hospitals (p < 0.001). The usage of advanced parameters such as stroke volume variation, cardiac index, and systemic vascular resistance was significantly higher in university hospitals, with a p value < 0.001. Transthoracic echocardiography was the most common tool used for high-risk surgical patients. The primary reasons for participants not utilising cardiac output monitoring include the lack of availability of such monitoring in their respective settings, which constitutes 66.9% of the respondents. The overwhelming majority of participants, namely 98%, expressed the belief that there is room for improvement in their present haemodynamic care. This study offers significant insights into the prevailing haemodynamic monitoring practices employed by Malaysian anaesthesiologists in the context of high-risk surgical patients. The findings have the potential to contribute to future educational initiatives and establish practice standards for haemodynamic monitoring in high-risk surgical procedures.

Background/Objectives: Hemodynamic monitoring is essential for guiding appropriate treatment by assessing cardiac output and volume status, as well as for preventing complications associated with excessive fluid administration. The EdgeFlow CW10 Plus is a device that extends conventional hemodynamic monitoring by incorporating pulmonary abnormality surveillance through B-line detection. This study aimed to evaluate whether the hemodynamic monitoring and pulmonary monitoring functions are well integrated, and verify the usability and efficiency of the system. Methods: A usability test was conducted with a panel of 15 medical professionals from diverse specialties and varying levels of clinical experience. Data from satisfaction surveys, heat maps, the System Usability Scale (SUS), and the NASA-TLX were analyzed to determine whether usability differences existed based on the duration of clinical experience. Results: The device demonstrated a high overall task success rate, averaging 93.2%. Regarding eye-tracking analysis based on clinical experience, it was observed that participants with more years of experience either failed to direct their gaze toward task-relevant user interface (UI) elements as effectively as those with fewer years of experience or showed similar patterns. Conclusions: The usability evaluation confirmed that the hemodynamic and pulmonary monitoring functions of the EdgeFlow CW 10 PLUS are well integrated, with the device demonstrating high usability and satisfaction. This integration is expected to support medical professionals in monitoring cardiac output and fluid status, facilitating timely therapeutic interventions while preventing complications related to fluid overload.

Bridging the Gap Between Hemodynamics and Monitoring

Hemodynamic monitoring has been part of the routine management of intensive care patients and high risk surgical patients since the advent of the pulmonary artery catheter (PAC) more than thirty years ago. The growing availability of new less invasive devices over the past decades has now made it possible to monitor cardiac output (CO) more often in the operating room, as well as in new clinical settings such as the emergency department. In this special issue papers have been arranged that discuss different aspects of hemodynamic monitoring, from technical issues to new clinical applications. The first paper titled “Perioperative intravascular fluid assessment and monitoring: a narrative review of established and emerging techniques” is a review on perioperative intravascular fluid assessment and monitoring. How cardiovascular physiology can be monitored is explained, and different technologies are presented. The second paper titled “Cardiac output assessed by invasive and minimally invasive techniques” is a review on all available technologies to monitor CO. The authors start from the PAC and carry on to present the more recent less invasive devices. The review covers technical aspects as well as clinical validation and use. The third paper titled “The effect of a hyperdynamic circulation on tissue Doppler values: a simulation in young adults during exercise” presents research done on healthy individuals undergoing strenuous exercise, using left ventricular tissue Doppler velocity (TDI), giving us new data on the use of TDI in hyperdynamic circulation. The fourth paper titled “The effect of airway pressure release ventilation on pulmonary catheter readings: specifically pulmonary capillary wedge pressure in a swine model” investigates the effect of the airway pressure release ventilation (APRV) on the PAC readings in an animal model. This papers gives new insights into the heart-lung interaction when using this new mode of ventilation. In the fifth paper titled “Clinical applications of heart rate variability in the triage and assessment of traumatically injured patients” heart rate variability (HRV) is explored. HRV represents a way of looking at the function of autonomic nervous system during stress conditions and has been studied in different areas as a predictor of morbidity and mortality. In this paper the authors focus on the use of HRV in trauma patients. The sixth paper titled “Recommendations for haemodynamic and neurological monitoring in repair of acute type A aortic dissection” gives a perspective on how hemodynamic monitoring should be used in conjunction with other clinical strategies. In this review the authors describe how hemodynamic monitoring can be combined with neurological monitoring in order to optimize the circulation guaranteeing adequate cerebral blood flow. The seventh paper titled “Assessing the left ventricular systolic function at the bedside: the role of transpulmonary thermodilution-derived indices” is a review on the use of transpulmonary thermodilution to measure CO and other derived variables. The authors focus on how these variables can be used to assess the left ventricular function in different clinical situations. Maurizio Cecconi Jamal A. Alhashemi Maxime Cannesson Christoph K. Hofer

Hemodynamic monitoring in the care of the critically ill neuroscience patient provides information that assists the clinician in minimizing secondary neuronal injury. Whereas no technology replaces the critical care nurse's physical assessment, hemodynamic and neurological monitoring provides additional data beyond what is possible with the clinical examination alone. If neurological technology, such as intracranial pressure monitoring, is not available, hemodynamic monitoring along with the neurological examination provides limited but useful information essential to minimizing secondary neuronal injury. The use of hemodynamic monitoring in critically ill neuroscience patients is best exemplified in the management of cerebral vasospasm after aneurysmal subarachnoid hemorrhage. Although improved outcomes have not been scientifically substantiated, multimodality monitoring of intracranial dynamics and systemic hemodynamics and manipulation of these parameters during hypertensive hypervolemic hemodilution therapy may lessen the incidence of cerebral infarction secondary to vasospasm. Monitoring systemic hemodynamics and intracranial dynamics simultaneously assists in prevention, prompt recognition, and effective treatment of neurological deterioration.

Hemodynamic disturbances cause half of the perioperative strokes following carotid endarterectomy (CEA). Guidelines strongly recommend strict pre- and postoperative blood pressure (BP) monitoring in CEA patients, but do not provide firm practical recommendations. Although in the Netherlands 50 centres perform CEA, no national protocol on perioperative hemodynamic, and cerebral monitoring exists. To assess current monitoring policies of all Dutch CEA-centres, a national survey was conducted. Between May and July 2017 all 50 Dutch CEA-centres were invited to complete a 42-question survey addressing perioperative hemodynamic and cerebral monitoring during CEA. Nonresponders received a reminder after 1 and 2 months. By November 2017 the survey was completed by all centres. Preoperative baseline BP was based on a single bilateral BP-measurement at the outpatient-clinic in the majority of centres (n = 28). In 43 centres (86%) pre-operative monitoring (transcranial Doppler (TCD, n = 6), electroencephalography (EEG, n = 11), or TCD+EEG (n = 26)) was performed as a baseline reference. Intraoperatively, large diversity for type of anaesthesia (general: 45 vs. local [LA]:5) and target systolic BP (>100 mm hg - 160 mm hg [n = 12], based on preoperative outpatient-clinic or admission BP [n = 18], other [n = 20]) was reported. Intraoperative cerebral monitoring included EEG+TCD (n = 28), EEG alone (n = 13), clinical neurological examination with LA (n = 5), near-infrared spectroscopy with stump pressure (n = 1), and none due to standard shunting (n = 3). Postoperatively, significant variation was reported in standard duration of admission at a recovery or high-care unit (range 3-48 hr, mean:12 hr), maximum accepted systolic BP (range >100 mm hg - 180 mm Hg [n = 32]), postoperative cerebral monitoring (standard TCD [n = 16], TCD on indication [n = 5] or none [n = 24]) and in timing of postoperative cerebral monitoring (range directly postoperative - 24 hr postoperative; median 3 hr). In Dutch centres performing CEA the perioperative hemodynamic and cerebral monitoring policies are widely diverse. Diverse policies may theoretically lead to over- or under treatment. The results of this national audit may serve as the baseline dataset for development of a standardized and detailed (inter)national protocol on perioperative hemodynamic and cerebral monitoring during CEA.

PMD22 - Hemodynamic Monitoring Can Reduce Costs on High Risk Patients WHO Underwent Large/Medium Surgical Procedures

Measuring the hemodynamic response to primary pharmacoprophylaxis of variceal bleeding: a cost-effectiveness analysis

The hemodynamic response to ss-blockers alone or with nitrates is highly predictive of efficacy in prevention of variceal bleeding. Hemodynamic monitoring (HDM) requires catheterization of the hepatic vein and measurement of the hepatic venous pressure gradient, the difference between wedged and free hepatic venous pressure. The aim of this study was to compare HDM with no HDM in patients considered for primary pharmacoprophylaxis of esophageal variceal bleeding. A decision model was constructed to compare HDM with no HDM in cirrhotic patients with moderate to large esophageal varices. Patients intolerant to beta-blocker therapy would undergo endoscopic variceal ligation; those with an inadequate hemodynamic response (HDR) to beta-blocker therapy could have nitrates added before ligation was considered. Variceal bleeding was treated with ligation, with transjugular intrahepatic portosystemic shunt (TIPS) reserved for refractory bleeding. Probabilities of treatment responses as well as risks of bleeding and mortality were based on published literature. Only direct costs were considered during the 5-yr time horizon. Outcomes were cost in United States dollars, survival length in life-years, and proportions of patients who experienced variceal bleeding, TIPS insertion, and mortality from any cause. In the base case analysis, HDM was either cost-saving ($2,523 US dollars /life-year gained) or cost-effective (incremental cost-effectiveness ratio of $5,200 US dollars/life-year saved) compared with no HDM, depending on whether nitrates were added to beta-blocker therapy. HDM reduced variceal bleeding by nearly 60% and had a small effect on all-cause mortality. In the sensitivity analysis, HDM was sensitive to the time horizon, as it was not cost-effective for a time horizon of <22 months and was not cost-saving before 49 months. The cost-effectiveness of HDM was not sensitive to reasonable variation in the probability of HDR to beta-blocker therapy, risk of bleeding, risk reduction with pharmacotherapy, or to the costs of HDM, bleeding, ligation, or TIPS. Probabilistic sensitivity analysis indicated that HDM was more effective and less costly 100% and 57% of the time, respectively. Compared with the current standard of no HDM, measuring the hemodynamic response of primary pharmacoprophylaxis substantially reduces the number of bleeding episodes and is cost-effective or cost-saving over a wide range of sensitivity analyses. A randomized trial of HDM is needed to verify its efficacy in clinical practice.

The current primary prophylaxis for esophageal variceal bleeding in cirrhotic patients consists of nonselective β-blocker (NSBB) therapy. However, only approximately half of the patients achieve a sufficient hemodynamic response to NSBB therapy. Clinical application of hemodynamic response monitoring is still under debate. The aim of this meta-analysis is to assess the potential clinical value of monitoring the hemodynamic response to NSBB therapy using hepatic venous pressure gradient (HVPG) measurements in the primary prophylaxis for variceal bleeding. A systematic literature search was performed in PubMed, Embase, Web of Science, and the COCHRANE Library. Randomized-controlled trials and case series that included cirrhotic patients receiving primary prophylaxis for variceal bleeding with NSBBs and hemodynamic response monitoring using HVPG measurements were included for analysis. The primary outcome measure was variceal bleeding. A fixed-effect analysis was carried out using the Mantel-Haenszel method for relative risks. Six of the 1172 papers found were selected on the basis of stringent selection criteria. Hemodynamic response (HVPG ≤12 mmHg and/or a reduction of ≥20%, or ≥10% in one study, from baseline) to β-blocker therapy was associated significantly with a lower risk of variceal bleeding (relative risk=0.13, 95% confidence interval=0.06-0.29) compared with a nonresponse. Patients achieving a hemodynamic response to NSBB therapy have a lower risk of variceal bleeding than hemodynamic nonresponders. Hemodynamic monitoring in primary prophylaxis is of potential clinical value and requires further assessment in large cohort randomized-controlled trials.

A substantial number of patients are at high-risk of intra- or post-operative complications or both. Most perioperative deaths are represented by patients who present insufficient physiological reserve to meet the demands of major surgery. Recognition and management of critical high-risk surgical patients require dedicated and effective teams, capable of preventing, recognize, start treatment with adequate support in time to refer patients to the satisfactory ICU level provision. The main task for health-care planners and managers is to identify and reduce this severe risk and to encourage patient’s safety practices. Inadequate tissue perfusion and decreased cellular oxygenation due to hypovolemia, heart dysfunction, reduced cardiovascular reserve, and concomitant diseases are the most common causes of perioperative complications. Hemodynamic, respiratory and careful sequential monitoring have become essential aspects of the clinical practice both for surgeons and intensivists. New monitoring techniques have changed significantly over the past few years and are now able to rapidly identify shock states earlier, define the etiology, and monitor the response to different therapies. Many of these techniques are now minimally invasive or non-invasive. Advanced hemodynamic and respiratory monitoring combines invasive, non-invasive monitoring skills. Non-invasive ultrasound has emerged during the last years as an essential operative and perioperative evaluation tool, and its use is now rapidly growing. Perioperative management guided by appropriate sequential clinical evaluation combined with respiratory and hemodynamic monitoring is an established tool to help clinicians to identify those patients at higher risk in the attempt to reduce the complications rate and potentially improve patient outcomes. This review aims to provide an update of currently available standard concepts and evolving technologies of the various respiratory and hemodynamic monitoring systems for the high-risk surgical patients, highlighting their potential usefulness when integrated with careful clinical evaluation.

Blood flow in peripheral arteriovenous fistulae and grafts as used for hemodialysis access can be derived from simultaneous measurements of 1) the amount of access recirculation (AR) induced by reversing the dialysis blood lines, and 2) the dialyzer blood flow rate (Qb). The hemodynamic monitor (HDM) uses magnetic principles to measure AR. The measurement is based on differential conductivity between arterial (A) and venous (V) blood flows in the dialysis blood tubing sets after the injection of hypertonic saline into the V line as a conductivity tracer. Access blood flow rates (Qa) derived from AR measurements by the HDM are predictive of access outcome. The measurement of AR is traditionally done from the comparison of urea levels simultaneously taken from the A and V blood lines and from the systemic circulation. Thus, the urea method can also be used to estimate access blood flow rates. The purpose of this study was to determine whether urea based Qa values are also predictive of outcome. Forty-one patients with arteriovenous fistulae (n = 25) or Gore-Tex grafts (n = 16) were studied by a standard protocol. The protocol involved temporarily reversing the A and V lines, taking three blood samples for urea estimation, performing an HDM recirculation test, and recording Qb as per the machine blood pump setting. The data allowed calculation of Qa by the HDM (Qa [HDM]) and urea (Qa [urea]) methods. Qa (HDM) was 1,177 +/- 887 ml/min (mean +/- standard deviation) and Qa (urea) 964 +/- 793 ml/min, a statistically significant difference (paired t-test p < 0.001). There was a significant linear correlation between the results (r = 0.94, p < 0.0001), but the regression equation also showed that Qa (urea) values were less than Qa (HDM). The influence of the Qa value on access outcome was determined after an 8 month follow-up. Nine of the 41 accesses were lost to clotting. Chi-square and discriminate analyses showed that Qa (HDM) significantly (p = 0.005) predicted access outcome, whereas Qa (urea) did not (p = 0.164). The specificity of a low Qa (HDM) in predicting access clotting was 0.78, compared with 0.62 for Qa (urea). The data show that although Qa can be estimated by the urea method, the finding of a low Qa (urea) is a poor predictor of access outcome and may lead to cost ineffective investigations.

Objective To investigate the accuracy of careful clinical evaluation in hemodynamic status and guidance of PiCCO monitor in clinical treatment.Methods A total of 96 hemodynamic unstable cases were evaluated prior to the insertion of the PiCCO catheter.The attending physician in charge of the patient was required to complete a questionnaire to predict the range of key hemodynamic variables for CI,GEDI,SVRI and EVLWI.Additionally,the attending was also asked to indicate a plan for therapy based on the predicted hemodynamic profile and decide if the predicted therapy plan was altered after the the first measurement of hemodynamic variables.Results The accurate prediction of hemodynamic variables was CI (55.2％),GEDI(60.4％),SVRI(63.5％) 和 EVLWI (78.1％),among which EVLWI had a higher accuracy(P ＜ 0.05).49％ doctors altered their planned therapy according to the result of the PiCCO information.Doctors had more difficulty in accurately predicting hemodynamic values in critical patients which APACHE Ⅱ scored 15 ～25 (42.3％ vs 67.9％ and 42.3 ％ vs 75.0％,x2 =4.755,5.231,P ＜ 0.05).The prediction of patients with acute myocardial infarction was more accurate than those of without acute myocardial infarction,and less to alter the planned therapy(21.1％ vs 55.8％,x2 =7.382,P =0.007).The patients of impaired oxygenation had less accurate predictions and less therapy alterations(32.3％ vs 56.9％,x2 =5.110,P =0.024).Attending was able to predict the hemodynamic status more accurately(63.9％ vs 40％,x2 =5.152,P =0.023) and alter the predicted therapy less(39.3％ vs 65.7％,x2 =6.189,P =0.013) in patients who were enrolled later.Conclusions Clinical evaluation in hemodynamic status of critically ill patients had a lower accuracy,the information obtained by PiCCO often instruct clinical doctors to choose the optimal treatment. Key words: Hemodynamics; Pulse; Forecasting/methods; THERAPY

Objective To evaluate the relationship between atherosclerosis and hemodynamic of coronary artery in mice detecting by ultrasound bio-microscopy flow imaging. Methods Double 14 20-week-old LDL-R-/- and C57BL/6 male mice were selected, and randomly divided into two groups in each genotype according to weight. Each two groups were fed to 28 weeks or 36 weeks age respectively with west diet. Coronary artery hemodynamics in these mice were assessed in vivo by Vevo®2100 ultrasound imaging system, then the intima-media thickness(IMT) of aorta in histopathology were analyzed. The differences of coronary artery hemodynamic parameters such as maximum velocity (Vmax), mean velocity (Vmean) and velocity time integral (VTI) were compared between mice of different genotypes of the same week and mice of different weeks of the same genotype. And the relationship between coronary artery hemodynamic in ultrasound and aortic IMT in histopathology were analyzed. Results ①All coronary hemodynamic parameters in LDL-R-/- mice were significantly lower than those of wild-type mice except the Vmax between two 28-week-old genotypes group at the same weeks of age of different genotypes (all P 0.05). ②The histopathological measurements of aortic IMT in LDL-R-/- mice were significantly higher than those of wild type mice(all P<0.05), and those of 36-week-old mice were significantly higher than those of 28-week-old mice(all P<0.05). ③All coronary hemodynamic parameters such as Vmax, Vmean and VTI were negatively correlated with pathological measurements of aortic IMT (r=-0.532, -0.423, -0.524; all P<0.05). Conclusions The parameters of coronary artery hemodynamics obtained by ultrasound bio-microscopy are well correlated with the pathological results of atherosclerosis. Ultrasound bio-microscopic flow imaging can be used as a new method to evaluate the degree of atherosclerosis in mice by detecting the hemodynamic parameters of coronary artery. Key words: Ultrasound bio-microscopy; Mice; Coronary artery; Hemodynamics; Atherosclerosis