Perioperative Point-of-Care Ultrasound and Transesophageal Echocardiography in Resource- Limited Settings-A Focus on Nepal and Bangladesh.

The use of point-of-care ultrasound (POCUS) and transesophageal echocardiography (TEE) in the perioperative and critical care setting is increasing worldwide. This increase has been driven by increasing educational opportunities and technologic advances. Nepal and Bangladesh are resource-limited countries where concerted efforts have been made to increase training in POCUS or TEE in the perioperative and critical care settings. This paper's focus is to present the current state of use and international efforts to improve education and skills in perioperative POCUS and TEE in Nepal and Bangladesh. The authors also examine the challenges to improving and expanding ultrasound use in the perioperative environment in resource- limited environments in general, using the Nepalese and Bangladeshi experiences as case studies. The authors have held multiple short courses in POCUS or TEE in Nepal and Bangladesh over the past several years. The authors found a high level of interest in learning POCUS and TEE skills among participants. They encountered challenges with maintaining continuing education and quality assurance for participants after the courses. They also identified barriers to incorporating ultrasound into daily practice in local hospitals. An increasing prevalence of cardiovascular disease will increase the need for diagnostic strategies for patients worldwide, including the use of POCUS and TEE, to manage patients in the perioperative and critical care settings. The courses held in Nepal and Bangladesh may serve as models to expand educational opportunities in POCUS and perioperative TEE in resource-limited settings.

Functional Outcomes of Type I Bicuspid Aortic Valve Repair With Annular Stabilization: Subcommissural Annuloplasty Versus External Subannular Aortic Ring.

BACKGROUND: In bicuspid aortic valve patients with nonaneurysmal root (<45 mm) and severe aortic insufficiency (AI), external subannular aortic ring (ESAR) is being increasingly utilized for annular stabilization, compared with traditional subcommissural annuloplasty (SCA). To this date, there is no comparative study assessing functional equivalence or superiority of ESAR over SCA. METHODS: From 2003 to 2017, 139 patients underwent type I bicuspid aortic valve repair, of which 50 patients underwent concomitant SCA and 24 underwent ESAR. Cases with suboptimal echocardiographic imaging were excluded, resulting in 38 patients in the SCA group and 20 patients in ESAR group. Intraoperative transesophageal echocardiography before and after procedure were retrospectively analyzed for 11 parameters in the functional aortic root complex. RESULTS: ESAR patients had larger preoperative annulus (28.3 ± 3.2 mm versus 29.8 ± 3.7 mm, p = 0.1) and left ventricular (LV) outflow tract (28.1 ± 3.5 mm versus 29.8 ± 4.0 mm, p = 0.1) diameters, with greater leaflet prolapse (3.4 ± 1.3 mm versus 4.3 ± 1.3, p = 0.02). In both groups, 100% freedom from AI greater than 1+ was achieved, with significant reduction of vena contracta (-3.0 ± 0.6 mm, p < 0.001; -3.2 ± 0.4 mm, p < 0.001) and level of eccentricity of AI jet (AI angle change: -24.3 ± 6.5 degrees, p = 0.002; -22.3 ± 7.2 degrees, p = 0.01). Reduction in LV dimensions (-7.1 ± 1.2 mm, p < 0.001; -8.9 ± 1.9 mm, p < 0.001), annulus (-3.4 ± 0.4 mm, p < 0.001; -5.1 ± 2.7 mm, p < 0.001), LV outflow tract (-2.3 ± 0.4 mm, p < 0.001; -4.4 ± 0.5 mm, p < 0.001), and degree of leaflet prolapse (-1.6 ± 0.4 mm, p = 0.005; -2.1 ± 0.4 mm, p = 0.001) was achieved in both groups. Comparison of postprocedure outcomes showed improved mean transvalvular gradients in ESAR (11.2 ± 5.7 mm Hg versus 7.1 ± 2.5 mm Hg, p = 0.003), with similar freedom from AI. CONCLUSIONS: In addition to providing equivalent and excellent freedom from AI, ESAR also renders a more robust annular reduction than SCA, along with improved transvalvular gradients.

Decreased preoperative functional status is associated with increased mortality following coronary artery bypass graft surgery.

OBJECTIVES: Functional status prior to coronary artery bypass graft surgery may be a risk factor for post-operative adverse events. We sought to examine the association between functional status in the 3 months prior to coronary artery bypass graft surgery and subsequent 180 day mortality. DESIGN, SETTING, AND PARTICIPANTS: We performed a single center retrospective cohort study in 718 adults who received coronary artery bypass graft surgery from 2002 to 2014. EXPOSURES: The exposure of interest was functional status determined within the 3 months preceding coronary artery bypass graft surgery. Functional status was measured and rated by a licensed physical therapist based on qualitative categories adapted from the Functional Independence Measure. MAIN OUTCOMES AND MEASURES: The main outcome was 180-day all-cause mortality. A categorical risk prediction score was derived based on a logistic regression model of the function grades for each assessment. RESULTS: In a logistic regression model adjusted for age, gender, New York Heart Association Class III/IV, chronic lung disease, hypertension, diabetes, cerebrovascular disease, and the Society of Thoracic Surgeons score, the lowest quartile of functional status was associated with an increased odds of 180-day mortality compared to patients with highest quartile of functional status [OR = 4.45 (95%CI 1.35, 14.69; P = 0.014)]. CONCLUSIONS: Lower functional status prior to coronary artery bypass graft surgery is associated with increased 180-day all-cause mortality.

Aortic Regurgitation in Acute Type-A Aortic Dissection: A Clinical Classification for the Perioperative Echocardiographer in the Era of the Functional Aortic Annulus.

The functional aortic annulus offers a clinical approach for the perioperative echocardiographer to classify the mechanisms of aortic regurgitation in acute type-A dissection. Comprehensive examination of the functional aortic annulus in this setting using transesophageal echocardiography can guide surgical therapy for the aortic root by considering the following important aspects: severity and mechanism of aortic regurgitation, extent of root dissection, and the pattern of coronary artery involvement. The final choice of surgical therapy also should take into account factors, such as patient presentation and surgical experience, to limit mortality and morbidity from this challenging acute aortic syndrome. This review explores these concepts in detail within the framework of the functional aortic annulus, detailed anatomic considerations, and the latest literature.

Nitrous oxide and perioperative outcomes.

There is emerging evidence related to the effects of nitrous oxide on important perioperative patient outcomes. Proposed mechanisms include metabolic effects linked to elevated homocysteine levels and endothelial dysfunction, inhibition of deoxyribonucleic acid and protein formation, and depression of chemotactic migration by monocytes. Newer large studies point to possible risks associated with the use of nitrous oxide, although data are often equivocal and inconclusive. Cardiovascular outcomes such as stroke or myocardial infarction were shown to be unchanged in previous studies, but the more recent Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia I trial shows possible associations between nitrous oxide and increased cardiovascular and pulmonary complications. There are also possible effects on postoperative wound infections and neuropsychological function, although the multifactorial nature of these complications should be considered. Teratogenicity linked to nitrous oxide use has not been firmly established. The use of nitrous oxide for routine anesthetic care may be associated with significant costs if complications such as nausea, vomiting, and wound infections are taken into consideration. Overall, definitive data regarding the effect of nitrous oxide on major perioperative outcomes are lacking. There are ongoing prospective studies that may further elucidate its role. The use of nitrous oxide in daily practice should be individualized to each patient's medical conditions and risk factors.

The ultrasound-guided retrolaminar block.

PURPOSE: Paravertebral blocks have gained in popularity and offer the possible benefit of reduced adverse effects when compared with epidural analgesia. Nevertheless, pulmonary complications in the form of inadvertent pleural puncture are still a recognized risk. Also, the traditional paravertebral blocks are often technically difficult even with ultrasound guidance and constitute deep non-compressible area injections. We present our experience with the first three patients receiving ultrasound-guided retrolaminar blocks for managing the pain associated with multiple rib fractures. CLINICAL FEATURES: The vertebral laminae are identified by ultrasound imaging in a paramedian sagittal plane by sequentially visualizing the pleura and ribs, transverse processes, and the corresponding laminae (from lateral to medial). The block needle is guided to contact the lamina, and the local anesthetic injectate is visualized under real-time imaging. A catheter is inserted and used for continuous analgesia. In three consecutive patients, verbal rating scale (VRS) pain scores were reduced from 10/10 to less than 5/10, and no technical difficulties, complications, or adverse effects were encountered. CONCLUSIONS: Successful analgesia was achieved in all three cases utilizing continuous infusion and intermittent boluses with ultrasound-guided retrolaminar blocks. These results show the feasibility of this approach for patients with multiple rib fractures.

Detecting intrinsic scattering changes correlated to neuron action potentials using optical coherence imaging.

We demonstrate how optical coherence imaging techniques can detect intrinsic scattering changes that occur during action potentials in single neurons. Using optical coherence tomography (OCT), an increase in scattering intensity from neurons in the abdominal ganglion of Aplysia californica is observed following electrical stimulation of the connective nerve. In addition, optical coherence microscopy (OCM), with its superior transverse spatial resolution, is used to demonstrate a direct correlation between scattering intensity changes and membrane voltage in single cultured Aplysia bag cell neurons during evoked action potentials. While intrinsic scattering changes are small, OCT and OCM have potential use as tools in neuroscience research for non-invasive and non-contact measurement of neural activity without electrodes or fluorescent dyes. These techniques have many attractive features such as high sensitivity and deep imaging penetration depth, as well as high temporal and spatial resolution. This study demonstrates the first use of OCT and OCM to detect functionally-correlated optical scattering changes in single neurons.

Optical coherence elastography of engineered and developing tissue.

Biomechanical elastic properties are among the many variables used to characterize in vivo and in vitro tissues. Since these properties depend largely on the micro- and macroscopic structural organization tissue, it is crucial to understand the mechanical properties and the alterations that occur tissues respond to external forces or to disease processes. Using a novel technique called coherence elastography (OCE), we mapped the spatially distributed mechanical displacements strains in a representative model of a developing, engineered tissue as cells began to proliferate attach within a three-dimensional collagen matrix. OCE was also performed in the complex tissue of the Xenopus laevis (African frog) tadpole. Displacements were quantified a cross-correlation algorithm on pre- and postcompression images, which were acquired using coherence tomography (OCT). The images of the engineered tissue were acquired over a 10-development period to observe the relative strain differences in various regions. OCE was able differentiate changes in strain over time, which corresponded with cell proliferation and matrix as confirmed with histological observations. By anatomically mapping the regional variation stiffness with micron resolution, it may be possible to provide new insight into the complex by which engineered and natural tissues develop complex structures.