Impact of ultrasound settings on lung vertical artifacts: an observational study in mechanically ventilated patients

The number of vertical artifacts (VA) in lung ultrasound (LUS) impacts patients’ clinical management. This study aimed to demonstrate the influence of ultrasound settings on the number of VA in patients under invasive mechanical ventilation (IMV).Patients under IMV were recruited for LUS including three breathing cycles with a motionless curvilinear probe on the thoracic region with the most VA. Three experts in LUS were randomly inquired about the number of VA [RL1] and blindly after altering settings for a total of 20 test recordings per patient. The correlation between expert classifications was tested after grading the classifications. The number of VA across clinicians was compared between baseline recordings and test conditions recordings to determine statistical differences.Twenty-nine patients were enrolled with a median SOFA score of 6 (and an interquartile range (median±IQR) of 3. IMV was mainly due to stroke (n=10) and pneumonia (n=6). LUS was made between days 1 and 6 (IQR). Baseline recordings showed a median VA number of 2±2 in inspiration and a median of 1±2 in expiration from a total of 3636 expert classifications with a strong agreement within patients. The probe frequency of 8MHz, artifact filtering, speckle reduction and frame average reduced the median VA number by one. The power of −20dB and dynamic range of 32dB abolished the VA. Gain above 90% increased the median number of VA by one.In thisin vivostudy, the LUS settings influenced the VA number in IMV patients, after controlling for physiological and operator confounders.