Three-dimensional myocardial strain estimation from volumetric ultrasound: experimental validation in an animal model

Although real-time three-dimensional echocardiography has the potential to allow for more accurate assessment of global and regional ventricular dynamics compared to the more traditional two-dimensional ultrasound examinations, it still requires rigorous testing and validation against other accepted techniques should it breakthrough as a standard examination in routine clinical practice. Very few studies have looked at a validation of regional functional indices in an in-vivo context. The aim of the present study therefore was to validate a previously proposed 3D strain estimation-method based on elastic registration of subsequent volumes on a segmental level in an animal model. Volumetric images were acquired with a GE Vivid7 ultrasound system in five open-chest sheep instrumented with ultrasonic microcrystals. Radial (epsilon(RR)), longitudinal (epsilon(LL)) and circumferential strain (epsilon(CC)) were estimated during four stages: at rest, during esmolol and dobutamine infusion, and during acute ischemia. Moderate correlations for epsilon(LL) (r=0.63; p<0.01) and epsilon(CC) (r=0.60; p=0.01) were obtained, whereas no significant radial correlation was found. These findings are comparable to the performance of the current state-of-the-art commercial 3D speckle tracking methods

High frequency percussive ventilation : an asset to existing ventilation modi in intraoperative care?

High frequency percussive ventilation (HFPV) is a ventilation mode that combines positive pressure ventilation with some advantages of high frequency ventilation. During HFPV, a pulsatile flow is generated with high frequency and low volumes. HFPV has been used in the intensive care unit (ICU) for several decades, in case of insufficient conventional positive pressure ventilation. However, literature on its use in intraoperative care is scarce. We hypothesize that HFPV might be a better alternative to existing ventilation modi during selected operative procedures or in patients with severely compromised pulmonary and/or cardiac function. In this paper, we explain the HFPV system, we zoom in on the physiological effects of HFPV, and we describe its potential role in the intraoperative setting. Results of existing studies show that, compared to other conventional ventilation modes, HFPV improves oxygenation and ventilation without jeopardizing hemodynamics. However, because of the low quality evidence regarding physiological effects and clinical effectiveness, and due to the complicated design and set-up of the HFPV ventilator, the use of HFPV in intraoperative care is currently very limited. We conclude that HFPV could potentially be an interesting ventilation mode for procedures requiring minimal respiratory motion or low airway pressures, however larger (comparative) study trials are required to evaluate its usability in the operating room in patients with compromised pulmonary and/or cardiac function

Hyperalgesia and fentanyl dosing in on-pump coronary artery bypass grafting: a prospective, randomised, double-blinded clinical trial

Background: Chronic post-sternotomy pain after coronary artery bypass grafting (CABG) is an underestimated complication. Pain has a major impact on quality of life. Increasingly, low-dose or even opioid-free anesthesia has been shown to be feasible and in some cases beneficial. Different intraoperative analgesic treatment strategies may significantly impact occurrence of hyperalgesia and subsequent pain in cardiac surgery. Objective: To investigate whether different intraoperative dosing regimens of fentanyl during CABG influence the area of hyperalgesia 24 and 48 hours postoperatively. As secondary endpoints, we investigated whether acute postoperative pain measured by the numerical rating scale (NRS) scores at 24 and 48 hours and the occurrence of chronic pain after 3, 6 and 12 months were influenced by perioperative fentanyl dosing. Design: Prospective, randomized double-blind clinical trial. Setting: A preliminary analysis of a randomized multicenter study (University Hospital of Ghent and the University Hospital of Basel), including patients undergoing elective on-pump CABG in University Hospital of Ghent. Methods: We screened 80 patients, of whom 66 were included and randomized into three groups: a high fentanyl regimen (20 mu g.kg-1 IBW (Ideal Body Weight)), a low dosing regimen (3 mu g.kg-1 IBW), or a Shibutani continuous dosing regimen. When extubated and responsive, protocolized pin-pricking was performed at 24 and 48h to evaluate the surface area of hyperalgesia. Additionally, patients are asked to report the Numeric Rating Scale (NRS) at 24h, 48h, as well as the occurrence of persistent pain at 3, 6, and 12 months. Additional preoperative rescue fentanyl dosing and postoperative remifentanil dosing were taken into account as possible confounders. Results: Primary endpoint: the difference in the measured area of hyperalgesia between the randomization groups was not significantly different. At 24h a mean area of 88 cm2, 90 cm2 and 96 cm2 was found in the low, high and Shibutani groups, respectively. At 48h areas of 91 cm2, 96 cm2 and 103 cm2 were measured in the respective groups. Secondary endpoints: significantly higher NRS scores were recorded at 24 hours in the low -dose group. A higher NRS score was found at 6 months in the Shibutani group compared to the other groups in the longer term. Postoperative administration of remifentanil is was not found to be a confounding cause of hyperalgesia. Conclusion: More short-term pain was reported in patients administered lower doses of fentanyl intraoperatively. Other clinically relevant differences in outcomes were not found. Our findings suggest that the benefits of opioid low anesthesia may not be as relevant to cardiac surgery with median sternotomy. The total postoperative opioid dosing (including remifentanil) could be a possible cause of hyperalgesia. Trial registration: EudraCT (European Union Drug Regulating Authorities Clinical Trials Database), the European database for all interventional clinical trials on medicinal products authorized in the European Union. Eudra CT number: 2017-003278-15, AGO/2017/005

Stroke volume variation and pulse pressure variation measured at pulmonary arterial level versus pulse pressure variation measured at systemic arterial level : an exploratory study

Problem: Optimized fluid management reduces morbidity and mortality in major operations, including cardiac surgery (1, 2). Validated dynamic parameters were developed to predict fluid responsiveness but have limitations (3-5). This study explores the potential added value of stroke volume variation and pulse pressure variation measured at pulmonary arterial level in predicting fluid responsiveness (6). Methods: In twenty adult patients undergoing coronary artery bridging and/or aortic valve replacement, the systemic and pulmonary arterial (SA and PA) pressure curves were stored using Datagrabber software. A custom-made MATLAB code automatically analyzed the pulse pressures, from which the SA and PA pulse pressure variations (PPV_SA and PPV_PA) were calculated. Simultaneously, stroke volumes in the pulmonary artery were measured and PA stroke volume variation (SVV_PA) was calculated. These three parameters were determined in both closed and open chest situations and further analyzed using RStudio software. Results: No correlation could be established between SVV_PA and fluid responsiveness as defined by PPV_SA above 12% (3). In the case of PPV_PA, a mild correlation was seen with the above-mentioned fluid responsiveness, with an R-2 of 25%. Bland Altman analysis of PPV_PA and PPV_SA showed proportional bias with broad limits of agreement. ROC curve analysis attempted to determine a new cutoff value for PPV_PA, which was 33% (sensitivity 100%, specificity 86%). Conclusions: SVV_PA could not be correlated with fluid responsiveness as previously defined. PPV_PA appears to be mildly correlated with fluid responsiveness and has a relatively faster increase in variation than PPV_SA. Therefore, a new fluid responsiveness cutoff for PPV_ PA is proposed. Further research is needed to confirm these findings and to explore further the sensitivity and specificity regarding fluid responsiveness

Catheter-based serratus anterior plane block vs. continuous wound infiltration for postoperative pain control following minimally invasive atrioventricular valve surgery : a randomized, prospective trial

Background: Minimally invasive cardiac surgery via mini-thoracotomy reduces surgical trauma compared to full sternotomy. However, thoracotomy can cause severe postoperative pain. Managing postoperative pain is challenging but critical for fast rehabilitation and avoidance of chronic pain. Our objective was to compare the efficacy of analgesia of a bolus in combination with continuous local anaesthetics using a serratus anterior plane block (SAPB) catheter versus a wound infiltration catheter (CWI) in patients after minimally invasive cardiac surgery. Design and setting: We conducted a monocentric, prospective, randomized controlled trial between January 2021 and August 2022. The study was performed at Ghent University Hospital, Belgium. Methods: Patients scheduled for minimally invasive cardiac surgery via thoracoscopy and mini-thoracotomy were randomized to receive either a SABP or a CWI catheter. Postoperatively, continuous ropivacaine 0.2% was started at 10ml/h, and a supplementary bolus of 30ml ropivacaine 0.5% was administered one hour before detubation. The catheter remained in place for at least 24 hours. The primary endpoint was opioid consumption during the first 48 hours postdetubation. Secondary endpoints were anti-emetic consumption, Numerical Analogue Score for 48 hours, length of stay in the Intensive Care Unit and hospital, and incidence of chronic pain. Qualitative data were compared using the Chi – Square test, quantitative data were analyzed with the Student’s t-test. Results: During the study period, a total of 21 patients received a SAPB catheter and 26 patients received a CWI catheter. No statistical significant differences were seen in baseline characteristics. In the first 48 hours postdetubation, morphine equivalent consumption was similar in both groups (p= 0.52), with no differences observed in the early, mid- or late postoperative phases. The total morphine equivalent dose was 21.8 mg in the SAPB and 18.6 mg in the CWI group. There were no significant differences in postoperative vomiting and nausea, length of stay in the Intensive Care Unit and in the hospital and chronic thoracic pain (23% and 33% for the SAPB and CWI group, respectively, p=0.54). Conclusion: This prospective study found no significant difference in postoperative opioid consumption between patients who received a serratus anterior plane block catheter and those who received a wound catheter with bolus and continuous ropivacaine, following minimally invasive cardiac surgery via right thoracoscopy and mini-thoracotomy

Assessing right ventricular function in the perioperative setting, part I : echo-based measurements

This article reviews transesophageal echocardiography-based assessment of perioperative right ventricular function and failure, including catheter-based methods, three-dimensional echocardiography, and their combination to make pressure-volume loops. It outlines right ventricular pathophysiology, multiple assessment methods, and their relationship to analogous transthoracic echocardiogram measurements. technologies used and developed for transthoracic or left ventricular assessment show significant limitations when applied to transesophageal assessment of the right ventricle. The article provides an overview of right ventricular assessment modalities that can be used in transesophageal echocardiography. Ultimately, clinicians must know limitations of measurements, synthesize information, and assess it in the clinical context

Assessing right ventricular function in the perioperative setting, part II : what about catheters?

An-depth assessment of right ventricular function is important in a many perioperative settings. After exploring 2-dimensional echo-based evaluation, other proposed monitoring modalities are discussed. Pressure-based methods of right ventricular appraisal is discussed. Flow-based assessment is reviewed. An overview of the state of current right ventricular 3-dimensional echocardiography and its potential to construct clinical pressure-volume loops in conjunction with pressure measurements is provided. An overview of right ventricular assessment modalities that do not rely on 2-dimensional echocardiography is discussed. Tailored selection of monitoring modalities can be of great benefit for the perioperative physician. Integrating modalities offers optimal estimations of right ventricular function