A New Scoring Model to Diagnose COVID-19 Using Lung Ultrasound in the Emergency Department
Condition: COVID-19 Pneumonia
MeSH terms: COVID-19; Emergencies
Study type: Observational [Patient Registry]

Summary: 
      Mortality in COVID-19 patients is significantly correlated with age, fever duration, cardiac
      history, and B-profile and areas of consolidation in LUS. However, it is negatively
      correlated with initial O2 saturation and ejection fraction. This study was aiming to design
      a new scoring model to diagnose COVID-19 using bedside lung ultrasound (LUS) in the emergency
      department (ED).
    

Detailed description: 
      Patients:

      The study recruited all patient with pulmonary symptoms and presented to ED between 27th
      March 2020 and 17th May 2020. Exclusion criteria were (i) patients with congestive heart
      failure (n= 7), (ii) patients with known interstitial lung fibrosis (n= 4), and (iii)
      patients with poor echo-window (n= 4). Patients were seen first at ED where they underwent
      the required investigations and then classified. Patients were questioned about symptoms
      suspecting COVID-19 infection. Those who met the suspected clinical and investigational
      criteria were given a standard mask and were rapidly transferred safely to a separate waiting
      and isolation area with available infrastructure and tools for hand and respiratory hygiene
      practice. If the patient was proved to be positive for COVID-19, he was sent to quarantine.
      For negative patients, they were admitted to intermediate or ICU according to their clinical
      status. All recruited patients underwent the followings: complete blood count (CBC), arterial
      blood gas (ABGs), RT-PCR assay to detect COVID-19, chest X-ray, chest CT, LUS, and
      echocardiography (according to its availability, with precautions for the operators and the
      probe similar to those exerted to LUS).

      LUS examination:

      Two trained medical personnel, one ICU physician and one ICU nurse, entered the isolation
      room respecting all the preventive measures for respiratory, droplet, and contact isolation
      provided by the world health organization for the COVID-19 outbreak. The ultrasound probe and
      the tablet were put in two different sterile, plastic probe and tablet covers. Imaging was
      performed using a curvilinear probe (2-5 MHz) with different devices according to the
      availability in each centre. Six-point LUS (three in each hemithorax) was performed as
      described in the bedside lung ultrasonography in emergency (BLUE) protocol [13].

      Statistical analysis:

      Statistical analysis included comparing different parameters between COVID-19
      positive-patients and COVID-19 negative-patients, using independent t-test for numerical
      variables and chi-square for categorical variables. All significantly different variables
      were entered in a forward stepwise binary logistic regression analysis to select the best
      model. After selecting the best model. The variable chosen in the last step was weighed using
      the odds ratios (ORs) calculated from the regression coefficient (β) for each variable, the
      ORs were multiplied by 0.125 to calculate a score for each variable and the number was
      rounded to the nearest integer giving of scoring system of 10 points. All study patients were
      scored. The cutoff point of the score was calculated using ROC analysis, and calculation of
      sensitivity and specificity was performed. Also, variables associated with mortality in
      COVID-19 positive were entered in a forward binary logistic regression, which selected the
      best model and the ORs were calculated for each variable using the regression coefficient
      (β). Before adding the variables in the regression analysis, the determination of the proper
      cutoff values of different contentious variables was done using ROC analysis. Patient Data
      were entered, checked, and analyzed using SPSS for Windows version 16 (SPSS, Inc. Chicago,
      IL, USA). For all the above mentioned statistical tests, the threshold of significance is
      fixed at a 5% level (p < 0.05).
    

Intervention name(s): ultra sound
Intervention type(s): Device
Intervention description(s): chest ultrasound
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        covid19 pneumonia at emergency room
      
Keywords: lung ultrasound