L’insuffisance rénale aiguë congestive en chirurgie cardiaque

Background: Every year, more than 2 million people undergo cardiac surgery including 15 000 Canadians (1). Acute kidney injury remain a frequent complication in this setting which can affect up to 39% of patients (2). This complication is associated with a significant increase in the risk of short-term and long-term mortality after cardiac surgery (1). Multiple mechanisms can lead to acute kidney injury in the peri-operative period which complexify prevention and treatment. Among them, multiple clinical factors can result in an increase in venous pressure leading to a state of systemic congestion deleterious to kidney function in addition to other organs. The detection of congestion at the bedside of patients after cardiac surgery could be used to identify patients at risk of developing congestive complications such as congestive acute kidney injury as well as opening possibilities for prevention and treatment. Doppler ultrasound is a non-invasive technology enabling the assessment of blood flow velocity within the venous system. A reduction of systemic venous compliance lead to the appearance of alterations in portal vein flow and intra-renal venous flow. The objectives of the work presented in this thesis were the following: To determine the prevalence and predictive factor associated with the appearance of venous flow alterations during the intra-operative and post-operative period, to determine if their detection is associated with acute kidney injury in the post-operative period and to determine the clinical significance of their detection in the immediate post-operative period. Main results: This thesis is comprised of 3 cohort studies including a total of 1497 ultrasound asessments in 362 patients. Alterations in venous Doppler signals were observed in a subtantial proportion of patients during the per-operative period, from 10.8% to 24.3% depending on the time of assessment and the site assessed. We observed significant correlations between venous Doppler alterations and other clinical markers of congestion including central venous pressure, NT-pro-BNP and fluid balance. Furthermore, we observed that portal flow pulsatility and abnormal patterns of intrarenal venous flow were correlated. Using repeated assessments in a cohort of 145 patients, we observed that portal flow pulsatility and severe alterations in intrarenal venous flow were associated with the subsequent development of acute kidney injury in the post-operative period. A re-analysis of this data suggested that a grading system combining mutliple Doppler assesments at intensive care admission after cardiac surgery including heaptic veins, the portal vein and intrarenal veins may be able to identify patients at risk of developping acute kidney injury with high specificity. Conclusions: In the context of cardiac surgery, Doppler ultrasound can be used to identify alterations in peripheral venous Doppler signals suggestive of a congestion phenomenon and may be able to anticipate complications related to venous congestion such as acute kidney injury.Contexte : Chaque année, plus de 2 millions de personnes subissent une chirurgie cardiaque, dont 15 000 Canadiens (1). L’insuffisance rénale aiguë demeure une complication fréquente chez les patients subissant une chirurgie cardiaque atteignant une incidence jusqu’à 39 % dans la période postopératoire (2). Cette complication est associée à une augmentation du risque de mortalité à court et long termes. Plusieurs mécanismes peuvent engendrer l’insuffisance rénale aiguë dans la période peropératoire, ce qui complexifie la prévention et le traitement. Parmi ceux-ci, divers facteurs peuvent engendrer une augmentation des pressions veineuses menant à un état de congestion systémique qui affecte la fonction des reins ainsi que celle des autres organes vitaux. La détection de la congestion au chevet des patients durant la période intraopératoire et postopératoire pourrait permettre d’identifier les individus à risque de développer des complications de nature congestive telles que l’insuffisance rénale aiguë ainsi que de mettre en place des stratégies de prévention et de traitement. L’échographie Doppler est une technologie non invasive qui permet d’évaluer la vélocité du sang dans le réseau veineux. La diminution de la compliance veineuse entraine l’apparition d’altérations du flot veineux de la veine porte et des veines intrarénales. Les objectifs des travaux présentés dans cette thèse étaient les suivants : déterminer la prévalence ainsi que les facteurs prédicteurs de l’apparition de ces altérations durant la période peropératoire; déterminer si la détection de ces altérations est en mesure de prédire l’apparition d’insuffisance rénale aiguë dans la période postopératoire; et déterminer quelle est la signification clinique de l’apparition de ces signes dans la période postopératoire immédiate. Résultats principaux : Les travaux contenus dans cette thèse comportent trois études de cohorte comprenant 1497 examens échographiques chez 362 patients. La présence d’altération du flot veineux a été observée chez une proportion substantielle des patients durant la période post-opératoire, allant de 10.8% à 24.3% selon le site intérrogé et le moment où l’examen est effectué. Nous avons observé des associations entre les altérations du flot veineux et les autres marqueurs de congestion incluant la pression veineuse centrale, la mesure du NT-pro-BNP et la balance liquidienne. De plus, nous avons observé que la pulsatilité du flot portal est corrélée aux altérations du signal Doppler dans les veines intrarénales. Grâce à des examens répétées effectuées dans une cohorte de 145 patients, nous avons observé que la pulsatilité du flot portal et la présence d’un profil compatible avec une anomalie sévère du flot intrarénal veineux étaient associées indépendamment avec la survenue subséquente d’insuffisance rénale aiguë durant la période postopératoire. Une réanalyse de ces données nous a permis de constater qu’un système de gradation combinant la présence des altérations du flot veineux à plusieurs sites, incluant les veines hépatiques, la veine porte et les veines intrarénales, au moment de l’admission aux soins intensifs permet d’indentifier les patients qui développeront une insuffisance rénale aiguë avec une spécificité élevée. Conclusions : Dans le contexte de la chirurgie cardiaque, l’échographie Doppler peut être utilisée au chevet afin d’indentifier des altérations du flot veineux périphérique suggestives d’un phénomène de congestion et d’anticiper les complications de nature congestive tel que l’insuffisance rénale aiguë

Doppler identified venous congestion in septic shock:protocol for an international, multi-centre prospective cohort study (Andromeda-VEXUS)

INTRODUCTION: Venous congestion is a pathophysiological state where high venous pressures cause organ oedema and dysfunction. Venous congestion is associated with worse outcomes, particularly acute kidney injury (AKI), for critically ill patients. Venous congestion can be measured by Doppler ultrasound at the bedside through interrogation of the inferior vena cava (IVC), hepatic vein (HV), portal vein (PV) and intrarenal veins (IRV). The objective of this study is to quantify the association between Doppler identified venous congestion and the need for renal replacement therapy (RRT) or death for patients with septic shock. METHODS AND ANALYSIS: This study is a prespecified substudy of the ANDROMEDA-SHOCK 2 (AS-2) randomised control trial (RCT) assessing haemodynamic resuscitation in septic shock and will enrol at least 350 patients across multiple sites. We will include adult patients within 4 hours of fulfilling septic shock definition according to Sepsis-3 consensus conference. Using Doppler ultrasound, physicians will interrogate the IVC, HV, PV and IRV 6-12 hours after randomisation. Study investigators will provide web-based educational sessions to ultrasound operators and adjudicate image acquisition and interpretation. The primary outcome will be RRT or death within 28 days of septic shock. We will assess the hazard of RRT or death as a function of venous congestion using a Cox proportional hazards model. Sub-distribution HRs will describe the hazard of RRT given the competing risk of death. ETHICS AND DISSEMINATION: We obtained ethics approval for the AS-2 RCT, including this observational substudy, from local ethics boards at all participating sites. We will report the findings of this study through open-access publication, presentation at international conferences, a coordinated dissemination strategy by investigators through social media, and an open-access workshop series in multiple languages. TRIAL REGISTRATION NUMBER: NCT05057611.</p

Fluid balance and renal replacement therapy initiation strategy : a secondary analysis of the STARRT-AKI trial

Background: Among critically ill patients with acute kidney injury (AKI), earlier initiation of renal replacement therapy (RRT) may mitigate fluid accumulation and confer better outcomes among individuals with greater fluid overload at randomization.Methods: We conducted a pre-planned post hoc analysis of the STandard versus Accelerated initiation of Renal Replacement Therapy in Acute Kidney Injury (STARRT-AKI) trial. We evaluated the effect of accelerated RRT initiation on cumulative fluid balance over the course of 14 days following randomization using mixed models after censoring for death and ICU discharge. We assessed the modifying effect of baseline fluid balance on the impact of RRT initiation strategy on key clinical outcomes. Patients were categorized in quartiles of baseline fluid balance, and the effect of accelerated versus standard RRT initiation on clinical outcomes was assessed in each quartile using risk ratios (95% CI) for categorical variables and mean differences (95% CI) for continuous variables.Results: Among 2927 patients in the modified intention-to-treat analysis, 2738 had available data on baseline fluid balance and 2716 (92.8%) had at least one day of fluid balance data following randomization. Over the subsequent 14 days, participants allocated to the accelerated strategy had a lower cumulative fluid balance compared to those in the standard strategy (4509 (- 728 to 11,698) versus 5646 (0 to 13,151) mL, p = 0.03). Accelerated RRT initiation did not confer greater 90-day survival in any of the baseline fluid balance quartiles (quartile 1: RR 1.11 (95% CI 0.92 to 1.34), quartile 2: RR 1.03 (0.87 to 1.21); quartile 3: RR 1.08 (95% CI 0.91 to 1.27) and quartile 4: RR 0.87 (95% CI 0.73 to 1.03), p value for trend 0.08).Conclusions: Earlier RRT initiation in critically ill patients with AKI conferred a modest attenuation of cumulative fluid balance. Nonetheless, among patients with greater fluid accumulation at randomization, accelerated RRT initiation did not have an impact on all-cause mortality.Peer reviewe

Real-time assessment of renal venous flow by transesophageal echography during cardiac surgery

Hemodynamic monitoring during cardiac surgery is currently based on pressure measurements from an arterial cannula and central venous catheter. While central venous pressure (CVP) is routinely measured during cardiac surgery, the hemodynamic impact of venous hypertension on end-organ perfusion often remains unappreciated. We present a case in which transesophageal echography (TEE) was used to observe the impact of CVP variations on intrarenal venous flow velocities during cardiac surgery. The patient provided written permission for publication of this report

Point-of-care ultrasound in end-stage kidney disease : beyond lung ultrasound

Purpose of review: Following the miniaturization of ultrasound devices, point-of-care ultrasound (POCUS) has been proposed as a tool to enhance the value of physical examination in various clinical settings. The objective of this review is to describe the potential applications of POCUS in end-stage renal disease patients (ESRD). Recent findings: With basic training, the clinician can perform pulmonary, vascular, cardiac, and abdominal POCUS at the bedside of ESRD patients. Pulmonary ultrasound can be used to quantify pulmonary congestion and for the differential diagnosis of dyspnea. Ultrasound of the inferior vena cava combined with simple cardiac ultrasound can be used to promptly investigate the mechanism of hemodynamic instability. Vascular ultrasound can be used for troubleshooting of arteriovenous fistula problems and for catheter installation. Multiple potential applications of POCUS in the ESRD population are reviewed, including areas of future research. Summary: Acquiring basic skills in POCUS may improve patient care through the rapid identification of threats, improved diagnostic abilities for common symptoms, and safer procedures. The adoption of POCUS in undergraduate, internal medicine and nephrology training curriculums will likely lead to a gradual introduction of this technology in the care of ESRD patients

The role of point-of-care ultrasound monitoring in cardiac surgical patients with acute kidney injury

The approach to the patient with acute kidney injury (AKI) after cardiac surgery involves multiple aspects. These include the rapid recognition of reversible causes, the accurate identification of patients who will progress to severe stages of AKI and the subsequent management of complications resulting from severe renal dysfunction. Unfortunately, the inherent limitations of physical examination and laboratory parameters results are often responsible for a sub-optimal clinical management. In this review article, we explore how Point-Of-Care ultrasound, including renal and extra-renal ultrasound, can be used to complement all aspects of the care of cardiac surgery patients with AKI, from the initial approach of early AKI to fluid balance management during renal replacement therapy. The current evidence is reviewed including knowledge gaps and future areas of research

Doppler renal resistance index for the prediction of response to passive leg-raising following cardiac surgery

Purpose: Doppler-based renal resistance index (RI) can be measured at the bedside of critically illpatients. This study was designed to assess if the RI predicted an increase in cardiac output (CO)following passive leg-raising (PLR) in patients admitted to the intensive care unit after cardiacsurgery.Methods: During this single center prospective study, Doppler assessment of RI and measure-ments of CO using the thermodilution method were performed, after surgery, in the intensive careunit before and after PLR. A positive response to PLR was defined as a 10% increase in CO.Results: We included 30 patients. The mean RI was higher before (0.694 60.069) than after PLR(0.679 6 0.069) (P 5 .02) with a median change of 20.012 (IQR: 20.042;0.000). Following PLR, 9patients (30%) had a >10% increase in CO. In patients with a positive PLR response, the decreasein the RI during PLR was more pronounced than in patients who did not respond to PLR (PLR 60.042 (IQR: 20.051; 20.040) vs PLR 620.008 (IQR: 20.032; 0.015) (P 5 .004). There was a sig-nificant negative association between RI change in response to PLR and a 10% increase in COfollowing PLR (OR: 1.63 (CI:1.07–2.47) (P 5 .02) per 20.01 change).Conclusion: An increase in CO following PLR was associated with a significant decrease in RI. Var-iations of RI in response to PLR should be further studied as a tool to predict fluid responsiveness.However, their clinical utility could be limited by the small magnitude of the variations

Assessment of left ventricular diastolic function by transesophageal echocardiography before cardiopulmonary bypass : clinical implications of a restrictive profile

Objective Left ventricular (LV) diastolic function can be assessed by transesophageal echocardiography before cardiopulmonary bypass in the setting of cardiac surgery. The objective of this study was to determine whether the assessment of LV diastolic dysfunction (LVDD) improves mortality risk prediction. Design Retrospective single-center cohort study. Setting Single tertiary cardiac surgery center. Participants Data from patients undergoing cardiac surgery using cardiopulmonary bypass (CPB) and for which an evaluation for LVDD was performed before CPB between February 1999 and November 2015. Interventions Cases were reviewed retrospectively from a transesophageal echocardiography hemodynamic database. LV diastolic function was graded as normal, impaired relaxation (grade 1), pseudo-normalization (grade 2), or restrictive (grade 3) determined by mitral inflow waves, tissue Doppler imaging of the mitral annulus, and pulmonary venous flow. The main outcome was in-hospital mortality. Measurements and Main Results A total of 760 patients were included, 144 (18.9%) patients with normal diastolic function, 331 (43.6%) patients with grade 1 LVDD, 218 (28.7%) patients with grade 2 LVDD, and 67 (8.8%) patients with grade 3 LVDD. In-hospital mortality occurred in 31 patients (4.1%). The presence of grade 3 LVDD was associated with an increased likelihood of in-hospital mortality (odds ratio [OR]: 19.39, confidence interval [CI]: 2.37-158.48, p = 0.006). In contrast, LV systolic dysfunction was not independently associated with increased mortality. When added to the Parsonnet score, the addition of diastolic function resulted in a net reclassification improvement of in-hospital mortality (NRI: 0.419 CI: 0.049-0.759, p = 0.02), and in integrated discrimination improvement (IDI: 0.0179 CI: 0.0049-0.031, p = 0.007). Difficult separation from CPB was observed more frequently in patients with grade 3 LVDD (62.9% v 36.1%, p = 0.01). Conclusions In contrast to LV systolic dysfunction, restrictive LVDD is associated with an increased risk of in-hospital mortality in cardiac surgical patients. Further studies should explore how this information may be used by the attending anesthesiologist to tailor perioperative management