Publications by authors named "Dirk Varelmann"

Background: Hypoxemia occurs with relative frequency during one-lung ventilation (OLV) despite advances in airway management. Lung perfusion scans are thought to be one of the most accurate methods to predict hypoxemia during OLV, but their complexity and costs are well-known limitations. There is a lack of preoperative stratification models to estimate the risk of intraoperative hypoxemia among patients undergoing thoracic surgery.

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Anesthesia for cardiac surgical patients with antiphospholipid antibody syndrome (APLS) presents challenges with monitoring anticoagulation during cardiopulmonary bypass. Additionally, this condition is associated with other autoimmune diseases and comorbidities that need to be considered in caring for these patients, and there is minimal evidence for specific strategies during cardiac surgery. Separately, Jehovah's Witness (JW) patients typically do not consent to receiving blood products, presenting an additional challenge for resuscitation during cardiac surgery and especially in the context of APLS.

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Introduction: Dexmedetomidine improves intrapulmonary shunt in thoracic surgery and minimizes inflammatory response during one-lung ventilation (OLV). However, it is unclear whether such benefits translate into less postoperative pulmonary complications (PPCs). Our objective was to determine the impact of dexmedetomidine on the incidence of PPCs after thoracic surgery.

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Despite the benefits established for multiple surgical specialties, enhanced recovery after surgery has been underused in cardiac surgery. A cardiac enhanced recovery after surgery summit was convened at the 102nd American Association for Thoracic Surgery annual meeting in May 2022 for experts to convey key enhanced recovery after surgery concepts, best practices, and applicable results for cardiac surgery. Topics included implementation of enhanced recovery after surgery, prehabilitation and nutrition, rigid sternal fixation, goal-directed therapy, and multimodal pain management.

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Objective: To validate and compare the performance of different pulmonary risk scoring systems to predict postoperative pulmonary complications (PPCs) in lung resection surgery.

Design: Retrospective cohort study SETTING: A historic single-center cohort of lung resection surgeries PARTICIPANTS: Adult patients undergoing lung resection surgery under 1-lung ventilation.

Interventions: None.

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Objectives: Regional anesthetic techniques, traditionally underutilized in cardiac surgery, may play a role in multimodal analgesia, effectively improving pain control and reducing opioid consumption. We investigated the efficacy of continuous bilateral ultrasound-guided parasternal subpectoral plane blocks following sternotomy.

Methods: We reviewed all opioid-naïve patients who underwent cardiac surgery via median sternotomy under our enhanced recovery after surgery protocol between May 2018 and March 2020.

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Background: One-lung ventilation for thoracic surgery represents a challenge due to the risk for hypoxemia and barotrauma. Dual-controlled ventilation (ie, pressure-regulated volume control [PRVC]) may confer improved lung mechanics compared with conventional ventilation (volume-controlled ventilation [VCV]). Our objective was to determine the association between ventilatory mode and pulmonary outcomes after lung resection surgery.

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Objective: To develop simple but clinically informative risk stratification tools using a few top demographic factors and biomarkers at COVID-19 diagnosis to predict acute kidney injury (AKI) and death.

Design: Retrospective cohort analysis, follow-up from 1 February through 28 May 2020.

Setting: 3 teaching hospitals, 2 urban and 1 community-based in the Boston area.

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MIT's Emergency-Vent Project was launched in March 2020 to develop safe guidance and a reference design for a bridge ventilator that could be rapidly produced in a distributed manner worldwide. The system uses a novel servo-based robotic gripper to automate the squeezing of a manual resuscitator bag evenly from both sides to provide ventilation according to clinically specified parameters. In just one month, the team designed and built prototype ventilators, tested them in a series of porcine trials, and collaborated with industry partners to enable mass production.

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Article Synopsis
  • Enhanced Recovery After Surgery (ERAS) pathways lead to better clinical outcomes, lower costs, and higher patient satisfaction in various surgical fields, including a growing application in cardiac surgery.
  • In a study involving 102 patients and comparing their outcomes with pre-ERAS controls, ERAS patients demonstrated significantly shorter median ventilation times, ICU stays, and hospital lengths of stay, indicating improved recovery.
  • Although the initial results are promising and show no negative impact on patient outcomes, further research is needed to confirm the long-term effectiveness of ERAS protocols in cardiac surgery.
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The COVID-19 pandemic has prompted an international effort to develop and repurpose medications and procedures to effectively combat the disease. Several groups have focused on the potential treatment utility of angiotensin-converting-enzyme inhibitors (ACEIs) and angiotensin-receptor blockers (ARBs) for hypertensive COVID-19 patients, with inconclusive evidence thus far. We couple electronic medical record (EMR) and registry data of 3,643 patients from Spain, Italy, Germany, Ecuador, and the US with a machine learning framework to personalize the prescription of ACEIs and ARBs to hypertensive COVID-19 patients.

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The year 2017 was a year dominated by large-scale clinical studies reporting the outcome of various interventions in cardiac surgery and heart failure (HF) patients, relevant to all cardiothoracic anesthesiologists. Among them were studies investigating the addition of levosimendan, an alternative inotropic agent, to standard management of patients with HF undergoing cardiac surgery. Also, corticosteroids have been used for various purposes in cardiac patients.

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Clinical research and outcome studies dominated the publication spectrum for the cardiothoracic anesthesiologist in 2016. Echocardiography is an important tool in the armamentarium of the cardiothoracic anesthesiologist. Technology is advancing at a fast pace: A new method to quantify the regurgitant volume in mitral regurgitation has been described in an experimental model and been validated in humans.

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Critical care management of the obstetric patient can present unique challenges. Parturients who present with respiratory distress can suffer from a multitude of etiologies, and each diagnosis must be pursued as appropriate to the clinical picture. Normal physiologic changes of pregnancy may obscure the presentation and diagnosis, and irrelevant of the cause, pregnancy may complicate the management of hypoxic and hypercarbic respiratory failure in this patient population.

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Background: Lung ultrasound (LUS) is a well-established method that can exclude pneumothorax by demonstration of pleural sliding and the associated ultrasound artifacts. The positive diagnosis of pneumothorax is more difficult to obtain and relies on detection of the edge of a pneumothorax, called the "lung point." Yet, anesthesiologists are not widely taught these techniques, even though their patients are susceptible to pneumothorax either through trauma or as a result of central line placement or regional anesthesia techniques performed near the thorax.

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Large multicenter, randomized controlled trials published in reputable journals had a large impact on the world of cardiothoracic anesthesia in 2015. We as cardiac anesthesiologists pride ourselves as being experts in applied physiology, physics, ultrasonography, and pharmacology/pharmacotherapy. The selected studies added to our knowledge in the fields of echocardiography, pharmacology, molecular biology, and genetics.

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Placing a flow-directed pulmonary artery catheter (PAC) can be difficult and lead to serious complications. We present the case of an attempted PAC insertion in a patient undergoing implantation of a left ventricular assist device. Although physiologic pressure waveforms were established, plausible measurements of cardiac output and pulmonary capillary wedge pressure were not initially obtainable.

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Aims: The rising number of cardiovascular implantable electronic devices has led to a steep increase in transvenous lead extractions (TLEs). Procedure-related, haemodynamically significant adverse events are uncommon during TLE yet remain an inevitable risk. While the use of transoesophageal echocardiography (TEE) as a guide to clinical decision-making during refractory circulatory instability has been well established, the specific utility of rescue TEE during TLE has not been comprehensively studied.

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Common practice during local anesthetic injection is to warn the patient using words such as: "You will feel a big bee sting; this is the worst part." Our hypothesis was that using gentler words for administration of the local anesthetic improves pain perception and patient comfort. One hundred forty healthy women at term gestation requesting neuraxial analgesia were randomized to either a "placebo" ("We are going to give you a local anesthetic that will numb the area and you will be comfortable during the procedure") or "nocebo" ("You are going to feel a big bee sting; this is the worst part of the procedure") group.

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