US Journal Club April, 2020: COVID-19 Edition

Paper #1:

Point-of-Care Lung Ultrasound findings in novel coronavirus disease-19 pnemoniae: a case report and potential applications during COVID-19 outbreak

Buonsenso, D et al. Eur Rev Med Pharmacol Sci. 2020 Mar;24(5):2776-2780. DOI: 10.26355/eurrev_202003_20549.

Full text: https://www.europeanreview.org/wp/wp-content/uploads/2776-2780.pdf

  • Introduction and background information 
    • The COVID-19 outbreak began December 2019 in Wuhan, China and has since become a global pandemic causing a characteristic viral pneumonia with ground-glass opacities on chest CT
    • The authors note that despite a large increase in publications regarding COVID, there are no reports yet of characteristic lung ultrasound findings for these patients. To illustrate these findings, the authors present a case report
  • Case report
    • History: A 52 year old male seen in the ED for flu-like illness. Patient had contact with multiple high-risk individuals
    • Vitals: O2 saturation of 90% on room air 
    • Exam: Bilateral crackles on lung auscultation 
    • Imaging: Chest x-ray showed left sided perihilar opacity
    • Eventually tested positive for COVID-19
  • Lung ultrasound
    • Performed with a wireless curvilinear probe connected to tablet in plastic bags
    • ED physician performed ultrasound while ED nurse stored/clipped all images without contacting the patient
    • Probe and tablet sterilized afterwards, placed into new sterile bags
    • Used a 12-zone technique with anterior, lateral and superior areas with both superior and inferior segments
    • Findings:
      • Irregular pleural lines with subpleural consolidations
      • Thick, confluent and irregular B-lines
    • Findings of a COVID negative (control) patient:
      • Normal pleural lines
      • A-lines and thin/regular B-lines (if present at all)
  • Discussion
    • Lung ultrasound findings suggest interstitial-alveolar damage
    • Bedside ultrasound is advantageous, particularly in the setting of a pandemic, as it can limit the number of people exposed to the patient including nursing staff and radiology techs
    • Authors note that prior studies have proposed chest CT as a “screening” tool for COVID infection given its higher sensitivity (98% sensitive) compared to viral PCR (71% sensitivity)1
    • However, multiple disadvantages exist with CT, especially in a pandemic, including having to clean CT scanner and exposure to multiple medical personnel. In addition, CT findings of COVID tend to occur later in the disease state
    • Ultrasound for COVID could also potentially be used in the outpatient setting, and in times of overwhelming patient visits, as a method of triage
  • Take home points
    • Lung ultrasound is an advantageous imaging modality in the setting of the COVID-19 pandemic
    • Characteristic findings include irregular pleural lines, subpleural consolidations and thick, confluent & irregular B-lines
    • POCUS has many advantages over CT and can help to prevent further spread of COVID      

References

  1. Fang Y et al. Sensitivity of Chest CT for COVID-19: Comparison to RT-PCR. Radiology. Feb 19 2020:200432. DOI: 10.1148/radiol.2020200432. [Epub ahead of print]

Paper #2:

A Preliminary Study on the Ultrasonic Manifestations of Peripulmonary Lesions of Non-Critical Novel Coronavirus Pneumonia (COVID-19)

Huang, Y et al. [PrePrint]. Feb 26 2020. DOI: 10.21203/rs.2.24369/v1

Full text: https://www.researchsquare.com/article/rs-14928/v1

  • Introduction and background information
    • COVID–19 generally begins in the terminal alveoli, which are close to the pleura and can be clearly observed by lung ultrasound 
    • In patients with limited mobility from the Emergency Department, or in those with rapidly progressive decompensation, timely evaluation is crucial for the adjustment of medical treatment plans
  • What was the primary objective of this study?
    • No reports on the ultrasonic findings of COVID–19 have been published so far, so this paper hopes to provide preliminary ultrasonic information of COVID–19 
  • Methods and study design
    • Retrospective analysis of 20 patients, treated from January to February 2020
    • Examination took place within 0-10 days after symptom onset
    • Inclusion criteria:
      • Epidemiological history, clinical manifestations, blood or respiratory specimens, and considered to be “non-critical” in nature
    • Used  convex array and linear probes. A protective barrier and 75% alcohol solution were used to protect and disinfect
    • 12-area examination method: divided the lung by the anterior axillary and posterior axillary lines into 3 areas: anterior, lateral, and posterior. Each area was subsequently divided further into inferior and superior aspects, with 6 total areas per lung,  12 per patient, for a total of 240 areas examined in the study
    • Images were analyzed by two physicians with at least five years of ultrasound experience
  • Results
    • 20 patients were enrolled, including 11 male and 9 female, with ages ranging 27–81 years, median 44.5 years
    • The proportion of B lines was higher in the lesions than in other areas (95%CI: 0.317–0.441)
    • The blood flow signs were fewer in the lesions than in other areas (95%CI: 0.008–0.121)
    • Analysis of lesions types:
      • Rough and discontinuous pleural line 36/240 → 15%
      • Subpleural consolidation 53/240 → 22%
      • Air bronchogram sign 37/240 → 15%
      • Visible B lines 91/240 → 38%
      • Localized pleural thickening 19/240 → 8%
      • Localized pleural effusion 24/240 → 10%
      • Poor blood flow in the consolidation with color doppler 50/53 → 94%
  • Discussion
    • Ultrasound images showed that the subpleural lesions in these patients were significantly different from reported lung lesions in various other pathologies, and included the following features:
      • COVID–19 foci are mainly observed in the bilateral posterior lung fields, especially in the inferior fields
      • Fused B lines and waterfall signs, where B lines become confluent and obscure a side region of the lung visible under the pleura. The B lines are in fixed position
      • The pleural line is unsmooth, discontinuous and interrupted
      • The subpleural lesions show patchy, or nodule consolidations
      • Larger consolidations may show sonographic air bronchograms
      • The involved interstitial tissues have localized thickening and edema, and there may be localized pleural effusion around the lesions
      • CDFI ultrasound shows insufficient blood supply in the lesions
      • High frequency linear array probe is suggested to be used for minor subpleural lesions, as it can provide rich information and improve diagnostic accuracy
    • When comparing CT and ultrasound, the two types of imaging were highly consistent, but CT showed more clear and complete intrapulmonary and apical lesions than ultrasound
    • However, ground glass opacity, consolidation shadow and air bronchogram sign were all specific to ultrasonic images. CT is inferior to ultrasound in showing the smaller peripulmonary lesions and pleural and peripulmonary effusion. Also, ultrasound can produce real-time and dynamic images 
  • Limitations
    • Small sample size
    • There were no control studies
    • Limited clinical information
  • Take home points
    • COVID–19 foci are mainly observed in the posterior and inferior lung fields
    • Ultrasound can show typical manifestations and has advantages over CT in the clinical diagnosis in non-critical COVID-19 patients

Paper #3:

Ultrasonography for the Confirmation of Endotracheal Tube Intubation: A Systematic Review and Meta-Analysis

Gottlieb, Michael et al. Annals of Emergency Medicine, Volume 72, Issue 6, 627 – 636. DOI: https://doi.org/10.1016/j.annemergmed.2018.06.024

Full text: https://www.annemergmed.com/article/S0196-0644(18)30555-9/fulltext

  • Introduction and background information 
    • Multiple methods exist for confirming endotracheal tube (ETT) placement including auscultation for bilateral breath sounds, condensation in ETT, end-tidal CO2, chest x-ray and direct visualization
    • A study from 2015 analyzing more than 17,000 adult ED patients undoing RSI by physician trainees found a rate of 3.3% of esophageal intubations1
    • Most colorimetric CO2 detectors require 5 – 6 breaths for confirmation which can delay care and increase risk of aspiration2    
    • In cardiac arrest patients, the use of waveform capnography, shows poor sensitivity, between 65 and 72%3-4
    • Transtracheal ultrasound is another modality for ETT confirmation, especially in cardiac arrest or other situations where traditional methods may be more challenging 
  • What was the primary outcome of this study?
    • The primary objective of this study is quantifying the diagnostic accuracy of ultrasound for ETT confirmation with a secondary outcome of time to confirmation
  • Methods and study design
    • Search of PubMed, Scopus, Cochrane database among others between 2007 and 2017
    • Inclusion criteria
      • All prospective or RCTs assessing transtracheal US
      • Patients > 18 years
      • Must have confirmatory test (end-tidal CO2, colorimetric, direct visualization)
    • Exclusion criteria
      • Case reports/case series/conference abstracts
      • Retrospective studies
    • Subgroup analysis included:
      • Provider specialty and experience
      • ED vs non-ED settings
      • Static versus dynamic technique
  • Results
    • 7,384 studies were identified and narrowed down to 17 studies with a total of 1,595 patients
    • 15 studies were prospective observation trials, 2 were RCTs
    • 8 studies used a dynamic technique while 9 used a static technique
    • Sonographers were EM physicians in 13 studies, anesthesiologists in 3 studies
    • 9 studies included residents, 5 included attendings
    • Heterogeneity very low across studies
    • Transtracheal ultrasonography was 98.7% sensitive and 97.1% specific for ETT confirmation
    • Mean time to confirmation was 13 seconds
  • Discussion
    • US is a highly accurate and rapid method for identification of endotracheal intubation
    • A prior meta-analysis of capnography for ETT confirmation showed sensitivity and specificity of 93% and 97% respectively
    • Especially useful for cardiac arrest or post-intubation arrest
    • Be careful not to press too hard on neck during intubation as to not obstruct the procedure
  • What were the strengths
    • Multiple studies from across the world adds to diversity of patients
    • Excluded case series and other low powered evidence
  • Were there any limitations?
    • Many studies had small sample sizes and used convenience sampling
    • Significant variation in sonographer training protocols and operator experience
    • Data spanned over 10 years during which time ultrasound has become more universal  
  • Take home points
    • This meta-analysis selected a highly diverse patient population over a 10 year span, mainly in the ED setting
    • Transtracheal ultrasound for ETT confirmation was found to be highly accurate and more sensitive than prior data on capnography 
    • Many of the studies included had small sample sizes with variation in sonographer training
    • This method likely has most utility when used in cardiac arrest patients or other situations in which either capnography may be unreliable or chest x-ray delayed 

References

  1. Brown, Calvin A. et al. Techniques, Success, and Adverse Events of Emergency Department Adult Intubations. Annals of Emergency Medicine, Volume 65, Issue 4, 363 – 370.e1. DOI: https://doi.org/10.1016/j.annemergmed.2014.10.036
  1. Walsh, B et al. Respiratory Care April 2011, 56 (4) 503-509; DOI: https://doi.org/10.4187/respcare.01175
  1. MacLeod, Bruce A et al. Verification of endotracheal tube placement with colorimetric end-tidal CO2 detection. Annals of Emergency Medicine, Volume 20, Issue 3, 267 – 270. DOI: https://doi.org/10.1016/S0196-0644(05)80937-0
  1. Takeda, Taku et al. The assessment of three methods to verify tracheal tube placement in the emergency setting. Resuscitation, Volume 56, Issue 2, 153 – 157.  DOI: https://doi.org/10.1016/S0300-9572(02)00345-3

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