The respiratory exchange ratio (RER), defined as the ratio of carbon dioxide (CO2) production to oxygen (O2) consumption, may be a non-invasive and continuously measurable alternative to lactate for identifying patients at risk of postoperative complications that has been examined in non-cardiac surgery. We investigated whether intraoperative RER predicts blood lactate levels and postoperative complications in cardiac surgery. This retrospective cohort study included adult patients undergoing cardiac surgery with cardiopulmonary bypass at Beth Israel Deaconess Medical Center in Boston, USA, between 2008 and 2020. Intraoperative minute-by-minute data of inspired and expired fractions of CO2 and O2 were analyzed. Univariable and a priori-defined multivariable logistic regression models were used to evaluate the association between the median RER during surgery, intraoperative lactate and 7-day major postoperative complications (European Perioperative Clinical Outcome Definitions). 324,646 RER calculations of 4,058 patients were included. 1,745 (43.0

BACKGROUND:Clinicians often administer 100% inspired oxygen (fraction of inspired oxygen [Fio2] = 1) for washout of volatile anaesthetics before tracheal extubation, potentially aggravating atelectasis formation and compromising oxygenation. We evaluated whether lower Fio2 during emergence from anaesthesia reduces atelectasis and improves oxygenation. METHODS:We conducted a single-centre, randomised controlled trial (NCT06538740) in 48 adult participants undergoing elective surgery under general anaesthesia. Participants were randomised to receive either pure oxygen (100%) or lower (70% or 40%) Fio2 for anaesthetic washout before extubation. The primary outcome was atelectasis, assessed as changes in centre of ventilation and end-expiratory lung volume using electrical impedance tomography. RESULTS:Twenty-four participants (mean age 57 [range: 19-82] yr; 42% female) were randomly allocated to receive pure oxygen and 24 received 40% or 70% Fio2. Participants receiving pure oxygen had a more ventral shift in the centre of ventilation (median [IQR], -0.3% [-2.2 to 1.3]), compared with lower Fio2 (1.3% [0.0-2.8]; P=0.041). Participants receiving pure oxygen also had a greater reduction in end-expiratory lung volume after extubation (-1067 [-1839 to -589] ml) compared with participants receiving lower Fio2 (-423 ml [-873 to -53]; P=0.006). There was no difference in end-expiratory lung volume between patients receiving 70% or 40% Fio2 (P=0.39). Spo2 (oxygen saturation measured by pulse oximetry) 10 min after extubation was higher in participants receiving 70% Fio2 (interaction P=0.028). CONCLUSIONS:Avoiding pure oxygen before extubation preserved end-expiratory lung volume with more dorsal distribution of ventilation. Postextubation oxygenation was optimal with 70% Fio2.

INTRODUCTION:Dexmedetomidine can attenuate delirium in patients who are critically ill, but evidence with regards to its preventive effect on postoperative delirium remains equivocal. We hypothesised that the risk of delirium after intra-operative dexmedetomidine administration varies depending on the dose administered and aimed to identify the optimum dose to mitigate delirium. METHODS:We included 114,786 adults undergoing general anaesthesia for non-cardiac, non-transplant surgery. Primary exposure was intra-operative dexmedetomidine dose in cumulative μg.kg-1 body weight, dichotomised into high vs. low dose based on the cohort median (0.49 μg.kg-1). Primary outcome was delirium within 7 days, identified from discharge notes, Confusion Assessment Method assessments and diagnostic codes. RESULTS:A total of 4804 (4.2%) patients received dexmedetomidine, with a median (IQR [range]) cumulative dose of 0.49 (0.28-0.84 [0.01-2.50]) μg.kg-1. Postoperative delirium occurred in 3227 (2.8%) patients. Compared with no dexmedetomidine, the risk of delirium was lower in patients receiving low doses (≤ 0.49 μg.kg-1) of dexmedetomidine (adjusted odds ratio 0.61, 95%CI 0.44-0.85, p = 0.004), but not among those receiving high doses (> 0.49 μg.kg-1) (adjusted odds ratio 1.06, 95%CI 0.84-1.34, p = 0.62). Fractional polynomial regression analyses suggested that doses between 0.25 μg.kg-1 and 0.35 μg.kg-1 were associated with the lowest delirium risk. Threshold regression and restricted cubic splines confirmed these findings. DISCUSSION:Low, but not high, dose dexmedetomidine administration was associated with lower risks of delirium, with optimal doses ranging between 0.25 μg.kg-1 and 0.35 μg.kg-1.

BACKGROUND: The recommendation for transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR) in patients 65 to 80 years of age is equivocal, leaving patients with a difficult decision. We evaluated whether TAVR compared to SAVR is associated with reduced odds for loss of independent living in patients ≤65, 66 to 79, and ≥80 years of age. Further, we explored mechanisms of the association of TAVR and adverse discharge. METHODS: Adult patients undergoing TAVR or SAVR within a large academic medical system who lived independently before the procedure were included. A multivariable logistic regression model, adjusting for a priori defined confounders including patient demographics, preoperative comorbidities, and a risk score for adverse discharge after cardiac surgery, was used to assess the primary association. We tested the interaction of patient age with the association between aortic valve replacement (AVR) procedure and loss of independent living. We further assessed whether the primary association was mediated (ie, percentage of the association that can be attributed to the mediator) by the procedural duration as prespecified mediator. RESULTS: A total of 1751 patients (age median [quartiles; min–max], 76 [67, 84; 23–100]; sex, 56% female) were included. A total of 27% (222/812) of these patients undergoing SAVR and 20% (188/939) undergoing TAVR lost the ability to live independently. In our cohort, TAVR was associated with reduced odds for loss of independent living compared to SAVR (adjusted odds ratio [ORadj] 0.19 [95% confidence interval {CI}, 0.14–0.26]; P < .001). This association was attenuated in patients ≤65 years of age (ORadj 0.63 [0.26–1.56]; P = .32) and between 66 and 79 years of age (ORadj 0.23 [0.15–0.35]; P < .001), and magnified in patients ≥80 years of age (ORadj 0.16 [0.10–0.25]; P < .001; P-for-interaction = .004). Among those >65 years of age, a shorter procedural duration mediated 50% (95% CI, 28–76; P < .001) of the beneficial association of TAVR and independent living. CONCLUSIONS: Patients >65 years of age undergoing TAVR compared to SAVR had reduced odds for loss of independent living. This association was partly mediated by shorter procedural duration. No association between AVR approach and the primary end point was found in patients ≤65 years of age.

Intraprocedural transesophageal echocardiography imaging is an integral part of percutaneous structural heart disease (SHD) interventions. The rapid growth in the number, scope, and complexity of SHD interventions has outpaced the efforts to develop training and proficiency standards in periprocedural imaging. At the Beth Israel Deaconess Medical Center in Boston, Massachusetts, the authors have developed a 6-month duration fellowship in interventional echocardiography for SHD to address this issue. The purpose of this fellowship is to train cardiac anesthesiologists to address the unique challenges of interventional echocardiography. In this paper, the authors describe the rationale for and specific features of this training program. Their fellowship curriculum follows a multimodal integrative approach to training in SHD imaging, which includes simulation sessions, online modules, deliberate practice in the clinical setting, and interdisciplinary team-based training. In the next several years, there will be an increased need for echocardiographers who are proficient in intraprocedural SHD imaging. In this article, the authors describe their experience with a competency-based curriculum for subspecialty anesthesia training in SHD imaging.

TheAnesthesia second leading cause of mortality in the world is cardiovascular disease (CVD), causing 17 million deaths in 2013. CVD disproportionately affects lowLow-Income Countries- and middle-income countriesMiddle-Income Countries (LMIC), which account for 80% of these deaths. The use of ultrasound technologyTechnology has been a mainstay in the medical field for formal diagnostic purposes for years and has recently received increased interest for point-of-care diagnostics and procedural guidance. Transesophageal echocardiographyEchocardiography (TEE) is routinely used for diagnosis and monitoring during cardiac surgeryCardiac surgery, and transthoracic echocardiographyEchocardiography (TTE) is increasingly used as a point-of-care diagnostic modality both in the perioperative setting and in critically ill patients. In recent years, there has been emergence of portable ultrasound devices that offer many of the functionalities of traditional ultrasound machines. These handheld portable ultrasound devices have been shown to be very effective as a diagnostic modality and are a promising technologyTechnology for increasing adoption of ultrasound use in LMIC. Significant trainingTraining and expertise is required to achieve a level of expertise needed to perform and interpret an echocardiographic examination. Traditional trainingTraining with direct supervision of an experienced and certified practitioner is not practical for widespread adoption of echocardiographyEchocardiography in LMIC. There is a range of simulatorsSimulators available in the market for replicating a TTE and TEE exams. These simulatorsSimulators give learners the added benefit of familiarizing themselves with echocardiographyEchocardiography before application in a patient care setting. A variety of simulatorsSimulators are available in the market across various price points, each with its own benefits and limitations, from static simulation to 2D and 3D imagingImaging, as well as AR capability. It is possible to develop curriculumsCurriculum that include simulatorsSimulators as part of the teaching to train learners in echocardiographyEchocardiography. Such technologyTechnology increases the number of possibilities for future applications and may help in the early diagnosis of deadly diseases such as RHD and CVD.

The year 2020 was marred by the emergence of a deadly pandemic that disrupted every aspect of life. Despite the disruption, notable research accomplishments in the practice of cardiothoracic anesthesiology occurred in 2020 with an emphasis on optimizing care, improving outcomes, and expanding what is possible for patients undergoing cardiac surgery. This year's edition of Noteworthy Literature Review will focus on specific themes in cardiac anesthesiology that include preoperative anemia, predictors of acute kidney injury following cardiac surgery, pain management modalities, anticoagulation strategies after transcatheter aortic valve replacement, mechanical circulatory support, and future directions in research.