Lung ultrasound may tailor ventilatory management in atelectasis after Unilateral Lung Injury

Ultrasonography is an imaging technique that may be used to tailor ventilatory therapy for unilateral lung damage because it enables the monitoring of changes in lung aeration after the application of positive end-expiratory pressure PEEP, finds a new case study.

Atelectasis is the term used to describe the partial or complete decrease of lung capacity. Atelectasis is a frequent condition in the critical care environment, and when it results in acute life-threatening hypoxia, it is important to re-expand it.

At the bedside, ultrasonography is capable of diagnosing atelectasis. Sonographically, this condition manifests as a subpleural echo-deficient zone or one with tissue-like echotexture. Additional sonographic signals may aid in distinguishing this from other causes of lung consolidation, such as cessation of lung sliding with a lung pulse and static air bronchogram. The benefit of lung ultrasonography over radiography and computed tomography is the dynamic evidence of the lack of lung expansion. Acute hypoxemia occurred in a patient hospitalised to the intensive care unit (ICU) with coronavirus illness and undergoing mechanical ventilation, according to a newly published case report. Bedside lung ultrasonography proved very helpful in establishing the diagnosis, monitoring the patient's reaction to treatment, and guiding the ventilator's fine-tuning.

A 56-year-old man with a history of epilepsy was brought to the ICU with severe pneumonia caused by SARS-CoV-2 coronavirus infection. He had severe hypoxemic respiratory failure two days after arrival and was intubated. He had a dramatic decrease in peripheral arterial oxygen saturation after 12 days of mechanical breathing. A chest X-ray revealed opacification of the left hemithorax with erasure of the cardiac region and left phrenic dome outlines.

Thoracic ultrasound was performed at the patient's bedside and revealed volumetric reduction of the pulmonary segment above the left diaphragm, the presence of a tissue pattern with hyperechoic punctiform images and no change in its characteristics during respiratory incursions, as well as the absence of lung sliding and cardiac vibrations visible at the pleural line, indicating left lower lobe atelectasis.

In order to re-expand the collapsed area, authors opted to use an Open Lung Approach guided by ultrasonography and lateral decubitus placement (affected lung positioned superiorly).

PEEP was raised from 8 to 20 cmH2O after a bolus dose of cisatracurium. A curvilinear probe positioned posterior to the axillary line demonstrated the elimination of the tissue-like pattern and the emergence of lung sliding with A lines suggesting reversal of atelectasis. This PEEP level was maintained for 4 minutes throughout the recruiting phase, and no hemodynamic instability occurred. The PaO2/FiO2 ratio climbed to 190 during lung recruitment and PEEP titration, and a fresh chest radiograph revealed obvious pulmonary reexpansion.

Atelectasis causes the lung to become less malleable and acts more like a solid resisting deformation. The function of lung recruitment may help to provide a uniform distribution of tidal ventilation and should be used to determine an appropriate PEEP to maintain an open lung and prevent cyclic collapse. Ultrasound may be used to assess lung aeration improvement during lung recruitment manoeuvres and PEEP titration. As lung density grows, so does lung aeration, and vice versa. When the ultrasonic tissue pattern indicative of lung consolidation is replaced by imaging of the pleural line with maintained lung sliding and the presence of a horizontal A-line, the nonaerated lung area reopens.

While ultrasonography enables customization of manoeuvre recruitment and PEEP titration, it is unable to identify overdistension caused by a rise in intrathoracic pressures. Lung ultrasonography is an imaging technique that may be used to tailor ventilatory therapy for unilateral lung damage because it enables the monitoring of changes in lung aeration after the application of PEEP.

Reference –

https://clinmedjournals.org/articles/ijccem/international-journal-of-critical-care-and-emergency-medicine-ijccem-7-132.php?jid=ijccem

Nunes RS, Barrientto LCP, Silva VB, Iazzetta KG, Jesus TBA, et al. (2021) Lung Recruitment Guided by Ultrasonography in Unilateral Lung Injury. Int J Crit Care Emerg Med 7:132.

doi.org/10.23937/2474-3674/1510132