Ten Influential Point-of-Care Ultrasound Papers: 2023 in Review.

In an effort to help keep busy clinicians up to date with the latest ultrasound research, our group of experts has selected 10 influential papers from the past 12 months and provided a short summary of each. We hope to provide emergency physicians, intensivists, and other acute care providers with a succinct update concerning some key areas of ultrasound interest.

Wave interference at the contralateral ear helps explain non-monotonic envelope interaural time differences as a function of azimuth.

Interaural time differences (ITDs), an important acoustic cue for perceptual sound-source localization, are conventionally modeled as monotonic functions of azimuth. However, recent literature and publicly available databases from binaural manikins demonstrated ITDs conveyed by the envelopes (ENV-ITDs) of high-frequency (≥2 kHz) signals that were non-monotonic functions of azimuth. This study demonstrates using a simple, time-dependent geometric model of an elliptic head that the back-traveling (longer) sound path around the head, delayed and added to the conventionally treated front-traveling path, can account for non-monotonic ENV-ITDs. These findings have implications for spatial-hearing models in acoustic and electric (cochlear-implant) hearing.

Ten Influential Point-of-Care Ultrasound Papers: 2022 in Review.

Keeping up with the latest developments in the point-of-care ultrasound (POCUS) literature is challenging, as with any area of medicine. Our group of POCUS experts has selected 10 influential papers from the past 12 months and provided a short summary of each. We hope to provide emergency physicians, intensivists, and other acute care providers with a succinct update concerning some key areas of ultrasound interest.

Machines that save lives in the intensive care unit: the ultrasonography machine.

This article highlights the ultrasonography machine as a machine that saves lives in the intensive care unit. We review its utility in the limited resource intensive care unit and some elements of machine design that are relevant to both the constrained operating environment and the well-resourced intensive care unit. As the ultrasonography machine can only save lives, if is operated by a competent intensivist; we discuss the challenges of training the frontline clinician to become competent in critical care ultrasonography followed by a review of research that supports its use.

Ten Influential Point-of-Care Ultrasound Papers: 2021 in Review.

The ongoing rapid expansion of point-of-care ultrasound (POCUS) and its corresponding supporting literature leaves the frontline clinician in a difficult position when trying to keep abreast of the latest developments. Our group of POCUS experts has selected ten influential POCUS-related papers from the past twelve months and provided a short summary of each. Our aim is to give to emergency physicians, intensivists, and other acute care providers key information, helping them to keep up to date on rapidly evolving POCUS literature.

Echocardiography findings in COVID-19 patients admitted to intensive care units: a multi-national observational study (the ECHO-COVID study).

PURPOSE: Severely ill patients affected by coronavirus disease 2019 (COVID-19) develop circulatory failure. We aimed to report patterns of left and right ventricular dysfunction in the first echocardiography following admission to intensive care unit (ICU). METHODS: Retrospective, descriptive study that collected echocardiographic and clinical information from severely ill COVID-19 patients admitted to 14 ICUs in 8 countries. Patients admitted to ICU who received at least one echocardiography between 1st February 2020 and 30th June 2021 were included. Clinical and echocardiographic data were uploaded using a secured web-based electronic database (REDCap). RESULTS: Six hundred and seventy-seven patients were included and the first echo was performed 2 [1, 4] days after ICU admission. The median age was 65 [56, 73] years, and 71% were male. Left ventricle (LV) and/or right ventricle (RV) systolic dysfunction were found in 234 (34.5%) patients. 149 (22%) patients had LV systolic dysfunction (with or without RV dysfunction) without LV dilatation and no elevation in filling pressure. 152 (22.5%) had RV systolic dysfunction. In 517 patients with information on both paradoxical septal motion and quantitative RV size, 90 (17.4%) had acute cor pulmonale (ACP). ACP was associated with mechanical ventilation (OR > 4), pulmonary embolism (OR > 5) and increased PaCO2. Exploratory analyses showed that patients with ACP and older age were more likely to die in hospital (including ICU). CONCLUSION: Almost one-third of this cohort of critically ill COVID-19 patients exhibited abnormal LV and/or RV systolic function in their first echocardiography assessment. While LV systolic dysfunction appears similar to septic cardiomyopathy, RV systolic dysfunction was related to pressure overload due to positive pressure ventilation, hypercapnia and pulmonary embolism. ACP and age seemed to be associated with mortality in this cohort.

Trajectories of hypoxemia and pulmonary mechanics of COVID-19 ARDS in the NorthCARDS dataset.

BACKGROUND: Understanding heterogeneity seen in patients with COVIDARDS and comparing to non-COVIDARDS may inform tailored treatments. METHODS: A multidisciplinary team of frontline clinicians and data scientists worked to create the Northwell COVIDARDS dataset (NorthCARDS) leveraging over 11,542 COVID-19 hospital admissions. The data was then summarized to examine descriptive differences based on clinically meaningful categories of lung compliance, and to examine trends in oxygenation. FINDINGS: Of the 1536 COVIDARDS patients in the NorthCARDS dataset, there were 531 (34.6%) who had very low lung compliance (< 20 ml/cmH2O), 970 (63.2%) with low-normal compliance (20-50 ml/cmH2O), and 35 (2.2%) with high lung compliance (> 50 ml/cmH2O). The very low compliance group had double the median time to intubation compared to the low-normal group (107.3 h (IQR 25.8, 239.2) vs. 39.5 h (IQR 5.4, 91.6)). Overall, 68.8% (n = 1057) of the patients died during hospitalization. In comparison to non-COVIDARDS reports, there were less patients in the high compliance category (2.2% vs. 12%, compliance ≥ 50 mL/cmH20), and more patients with P/F ≤ 150 (59.8% vs. 45.6%). There is a statistically significant correlation between compliance and P/F ratio. The Oxygenation Index is the highest in the very low compliance group (12.51, SD(6.15)), and lowest in high compliance group (8.78, SD(4.93)). CONCLUSIONS: The respiratory system compliance distribution of COVIDARDS is similar to non-COVIDARDS. In some patients, there may be a relation between time to intubation and duration of high levels of supplemental oxygen treatment on trajectory of lung compliance.

The Utility of Point-of-Care Ultrasound in the Pediatric Intensive Care Unit.

Objectives: Point of care ultrasound (POCUS) in adult critical care environments has become the standard of care in many hospitals. A robust literature shows its benefits for both diagnosis and delivery of care. The utility of POCUS in the pediatric intensive care unit (PICU), however, is understudied. This study describes in a series of PICU patients the clinical indications, protocols, findings and impact of pediatric POCUS on clinical management. Design: Retrospective analysis of 200 consecutive POCUS scans performed by a PICU physician. Patients: Pediatric critical care patients who required POCUS scans over a 15-month period. Setting: The pediatric and cardiac ICUs at a tertiary pediatric care center. Interventions: Performance of a POCUS scan by a pediatric critical care attending with advanced training in ultrasonography. Measurement and Main Results: A total of 200 POCUS scans comprised of one or more protocols (lung and pleura, cardiac, abdominal, or vascular diagnostic protocols) were performed on 155 patients over a 15-month period. The protocols used for each scan reflected the clinical question to be answered. These 200 scans included 133 thoracic protocols, 110 cardiac protocols, 77 abdominal protocols, and 4 vascular protocols. In this series, 42% of scans identified pathology that required a change in therapy, 26% confirmed pathology consistent with the ongoing plans for new therapy, and 32% identified pathology that did not result in initiation of a new therapy. Conclusions: POCUS performed by a trained pediatric intensivist provided useful clinical information to guide patient management.

Criteria, Processes, and Determination of Competence in Basic Critical Care Echocardiography Training: A Delphi Process Consensus Statement by the Learning Ultrasound in Critical Care (LUCC) Initiative.

BACKGROUND: With the paucity of high-quality studies on longitudinal basic critical care echocardiography (BCCE) training, expert opinion guidelines have guided BCCE competence educational standards and processes. However, existing guidelines lack precise detail due to methodological flaws during guideline development. RESEARCH QUESTIONS: To formulate methodologically robust guidelines on BCCE training using evidence and expert opinion, detailing specific criteria for every step, we conducted a modified Delphi process using the principles of the validated AGREE-II tool. Based on systematic reviews, the following domains were chosen: components of a longitudinal BCCE curriculum; pass-grade criteria for image-acquisition and image-interpretation; and formative/summative assessment and final competence processes. STUDY DESIGN AND METHODS: Between April 2020 and May 2021, a total of 21 BCCE experts participated in four rounds. Rounds 1 and 2 used five web-based questionnaires, including branching-logic software for directed questions to individual panelists. In round 3 (videoconference), the panel finalized the recommendations by vote. During the journal peer-review process, Round 4 was conducted as Web-based questionnaires. Following each round, the agreement threshold for each item was determined as ≥ 80% for item inclusion and ≤ 30% for item exclusion. RESULTS: Following rounds 1 and 2, agreement was reached on 62 of 114 items. To the 49 unresolved items, 12 additional items were added in round 3, with 56 reaching agreement and five items remaining unresolved. There was agreement that longitudinal BCCE training must include introductory training, mentored formative training, summative assessment for competence, and final cognitive assessment. Items requiring multiple rounds included two-dimensional views, Doppler, cardiac output, M-mode measurement, minimum scan numbers, and pass-grade criteria. Regarding objective criteria for image-acquisition and image-interpretation quality, the panel agreed on maintaining the same criteria for formative and summative assessment, to categorize BCCE findings as major vs minor and a standardized approach to errors, criteria for readiness for summative assessment, and supervisory options. INTERPRETATION: In conclusion, this expert consensus statement presents comprehensive evidence-based recommendations on longitudinal BCCE training. However, these recommendations require prospective validation.

Interaural-time-difference thresholds for broad band-limited pulses are affected by relative bandwidth not temporal envelope sharpness.

Humans are sensitive to interaural time differences (ITDs) conveyed by slow modulations on high-frequency carrier signals. Sensitivity appears to be affected by temporal envelope sharpness, but it is unclear if there is a limit to which sharpness affects sensitivity. Pulse trains were varied in relative bandwidth (re: critical bandwidths) and center frequency. ITD sensitivity increased with increasing bandwidth. There was no effect of center frequency when relative bandwidths were analyzed, suggesting that the temporal envelope sharpness (concomitantly absolute bandwidth in Hz) did not affect performance. Rather, sensitivity was most easily explained by recruitment of additional auditory channels.

Basic ultrasound head-to-toe skills for intensivists in the general and neuro intensive care unit population: consensus and expert recommendations of the European Society of Intensive Care Medicine.

PURPOSE: To provide consensus, and a list of experts' recommendations regarding the basic skills for head-to-toe ultrasonography in the intensive care setting. METHODS: The Executive Committee of the European Society of Intensive Care (ESICM) commissioned the project and supervised the methodology and structure of the consensus. We selected an international panel of 19 expert clinicians-researchers in intensive care unit (ICU) with expertise in critical care ultrasonography (US), plus a non-voting methodologist. The panel was divided into five subgroups (brain, lung, heart, abdomen and vascular ultrasound) which identified the domains and generated a list of questions to be addressed by the panel. A Delphi process based on an iterative approach was used to obtain the final consensus statements. Statements were classified as a strong recommendation (84% of agreement), weak recommendation (74% of agreement), and no recommendation (less than 74%), in favor or against. RESULTS: This consensus produced a total of 74 statements (7 for brain, 20 for lung, 20 for heart, 20 for abdomen, 7 for vascular Ultrasound). We obtained strong agreement in favor for 49 statements (66.2%), 8 weak in favor (10.8%), 3 weak against (4.1%), and no consensus in 14 cases (19.9%). In most cases when consensus was not obtained, it was felt that the skills were considered as too advanced. A research agenda and discussion on training programs were implemented from the results of the consensus. CONCLUSIONS: This consensus provides guidance for the basic use of critical care US and paves the way for the development of training and research projects.

Optimization of Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea With Ultrasound Assessment of Tongue Movement.

BACKGROUND: Hypoglossal nerve stimulation (HGNS) is an Food and Drug Administration-approved therapy for obstructive sleep apnea. Initial programming of HGNS is based on the observation of anterior tongue movement, which may not reflect opening at the retroglossal airway. We developed an ultrasonographic technique to assess the base of tongue movement with HGNS to be used to optimize the initial voltage settings. STUDY QUESTION: This study aimed to investigate the use of ultrasound to assess tongue movement with HGNS and related this measure to the apnea hypopnea index (AHI) on subsequent home sleep apnea testing or in-laboratory polysomnography with therapy. STUDY DESIGN: Seventeen subjects (n = 17) implanted with HGNS were enrolled at least 1 month postimplantation. Ultrasonographic measures were then used to optimize HGNS voltage to produce observable base of tongue protrusion without producing discomfort. Responders were defined as a reduction in AHI > 50% and an AHI of <20 events/h. RESULTS: There were 17 subjects, 11 men and 6 women, with age = 64.6 ± 9.8 years, body mass index = 27.9 ± 2.7 kg/m2, and pretreatment AHI = 36.5 ± 14.4/h, T-90% = 10.7 ± 14.8%. The mean hyoid bone excursion (HBE) in responders = 1.0 ± 0.13 cm versus 0.82 ± 0.12 cm in nonresponders (P = 0.017). HBE was correlated with AHI during HGNS treatment (coef. -0.54, P = 0.03). Best subsets regression analysis using treatment-based AHI as the dependent variable and age, body mass index, baseline AHI, HBE, and HGNS voltage as independent variables showed that HBE (coef. -44.6, P = 0.044) was the only independent predictor of response. Receiver operator curve analysis showed that HBE > 0.85 cm had a sensitivity of 83.3% and specificity of 80.0% with a positive likelihood ratio of 4.17 to predict responder status. CONCLUSION: We demonstrated that ultrasound assessment of HBE during HGNS programming is a useful tool to optimize therapy.

Transmission of Binaural Cues by Bilateral Cochlear Implants: Examining the Impacts of Bilaterally Independent Spectral Peak-Picking, Pulse Timing, and Compression.

Acoustic hearing listeners use binaural cues-interaural time differences (ITDs) and interaural level differences (ILDs)-for localization and segregation of sound sources in the horizontal plane. Cochlear implant users now often receive two implants (bilateral cochlear implants [BiCIs]) rather than one, with the goal to provide access to these cues. However, BiCI listeners often experience difficulty with binaural tasks. Most BiCIs use independent sound processors at each ear; it has often been suggested that such independence may degrade the transmission of binaural cues, particularly ITDs. Here, we report empirical measurements of binaural cue transmission via BiCIs implementing a common "n-of-m" spectral peak-picking stimulation strategy. Measurements were completed for speech and nonspeech stimuli presented to an acoustic manikin "fitted" with BiCI sound processors. Electric outputs from the BiCIs and acoustic outputs from the manikin's in-ear microphones were recorded simultaneously, enabling comparison of electric and acoustic binaural cues. For source locations away from the midline, BiCI binaural cues, particularly envelope ITD cues, were found to be degraded by asymmetric spectral peak-picking. In addition, pulse amplitude saturation due to nonlinear level mapping yielded smaller ILDs at higher presentation levels. Finally, while individual pulses conveyed a spurious "drifting" ITD, consistent with independent left and right processor clocks, such variation was not evident in transmitted envelope ITDs. Results point to avenues for improvement of BiCI technology and may prove useful in the interpretation of BiCI spatial hearing outcomes reported in prior and future studies.