Lung Ultrasound Scans During Whole Lung Lavage

A 30-year-old woman who was a life-long nonsmoker presented to the outpatient pulmonary clinic with progressively worsening dyspnea. Her medical history was significant for exercise-induced asthma and chronic rhinitis. Since high school, she experienced progressive chest tightness, exertional dyspnea, and cough producing thick sputum. Her medications included fluticasone, levalbuterol inhaler, and montelukast. There was no history of environmental inhalational exposures. On physical examination, her lungs revealed fine crackles mostly at the bases on auscultation. Although her resting oxygen saturation was 94% on room air, it decreased to 87% within 1 minute of walking activity at slow pace. Her most recent pulmonary function test showed an FEV1 75% predicted, FVC 66% predicted, FEV1/FVC 89%, total lung capacity 68% predicted and diffusing capacity of the lungs for carbon monoxide 57% predicted. Chest radiograph showed bilateral lower lung predominant mixed interstitial and alveolar opacities (Fig 1). High-resolution CT demonstrated bilateral alveolar filling process with peripheral smooth septal line thickening and ground-glass opacities (Fig 2A). These abnormalities were in a patchy distribution in the subpleural areas and more confluent in the basal lower lobes (Fig 2B). There was no traction bronchiectasis or honeycombing to specifically indicate a fibrotic component to the disease process.Figure 2A, Noncontrast CT chest scan axial view shows bilateral ground-glass opacities located mostly at the periphery of the lung parenchyma. B, Coronal view CT chest scan shows lower lobe predominance.View Large Image Figure ViewerDownload Hi-res image Download (PPT) A diagnostic bronchoscopy was performed. The BAL of the right middle lobe yielded a cloudy whitish fluid on visual examination that was suggestive of pulmonary alveolar proteinosis (PAP). The diagnosis was confirmed with a positive Periodic-Acid-Schiff staining. Granulocyte macrophage colony-stimulating factor (GM-CSF) autoantibody concentration was sent that resulted in an abnormally elevated value (72.6 μg/mL; normal reference value, <5.0 μg/mL). Weeks after, the patient was brought to the operating room; after induction of general anesthesia, a bilateral whole lung lavage (WLL) was performed (Fig 3). We performed a lung point-of-care ultrasound (POCUS) examination using a phased array transducer (longitudinal view, mid-axillary line) during both the instillation of normal saline solution (Video 1) and re-recruitment phases (Video 2) of the WLL procedure. Question: Which lung ultrasound scan features are present in patients with PAP and throughout WLL? Answer: Video 1 shows the instillation phase where, initially, lung POCUS reveals a smooth pleural surface and diffuse B-lines (and obliteration of normally seen A-lines). This finding suggests a subpleural component of an alveolar interstitial syndrome During WLL, the instillation of the saline solution leads to progressive consolidation, with the residual air appearing in the form of air bronchograms. As saline solution instillation continues, it leads to progressive de-aeration of the lung that leads to complete atelectasis. The transition between atelectatic and aerated lung is demonstrated by a bright, hyperechoic area (shred sign) that begins in the caudal portion of the lung field and progresses toward the cephalad lung field as more volume of saline solution is administered. Video 2 shows reexpansion (recruitment) of the lung parenchyma by the reverse process, with increasing aerated lung beginning in the cephalad central lung field and progressive caudal reduction in alveolar consolidation. B-lines reoccur; the residual interstitial edema in the now ventilated lung. Ultrasonographic examination of healthy lung parenchyma demonstrates a “normal” reverberation artifact, called A-lines. A-lines are created when ultrasound waves reflect off the air-tissue interface in the pleural line and, subsequently, rereflect off the ultrasound probe.1Dietrich C.F. Mathis G. Blaivas M. et al.Lung B-line artefacts and their use.J Thorac Dis. 2016; 8: 1356-1365Crossref PubMed Scopus (75) Google Scholar B-lines, sometimes referred to as lung rockets or comet tail artifacts, suggest an interstitial process. B-lines are generated when ultrasound waves enter the small air-fluid interface in the pleura and reverberate.1Dietrich C.F. Mathis G. Blaivas M. et al.Lung B-line artefacts and their use.J Thorac Dis. 2016; 8: 1356-1365Crossref PubMed Scopus (75) Google Scholar This results in a long vertical hyperechoic ray originating from the pleural line and extending to the lung base, obliterating A-lines. PAP is a rare lung disease in which pulmonary surfactant is not removed properly from the alveoli.2Shah P.L. Hansell D. Lawson P.R. Reid K.B. Morgan C. Pulmonary alveolar proteinosis: clinical aspects and current concepts on pathogenesis.Thorax. 2000; 55: 67-77Crossref PubMed Scopus (213) Google Scholar This may be secondary to some defects in the GM-CSF signaling that can be either autoimmune or, less commonly, congenital.3Khan A. Agarwal R. Pulmonary alveolar proteinosis.Respir Care. 2011; 56: 1016-1028Crossref PubMed Scopus (40) Google Scholar In our case, the high level of GM-CSF autoantibody concentration suggested an autoimmune cause. As the proteinaceous material accumulates in the alveoli, we expected and confirmed the presence of diffuse B-lines throughout all anterior, lateral, and posterior lung fields with POCUS. WLL is the most common accepted nonsystemic therapy for patients with symptomatic PAP.3Khan A. Agarwal R. Pulmonary alveolar proteinosis.Respir Care. 2011; 56: 1016-1028Crossref PubMed Scopus (40) Google Scholar This is performed by achieving lung isolation with a double lumen endotracheal tube and instilling, in a controlled and methodical fashion, warm normal saline solution into the nonventilated lung. There has been some interest in use of ultrasound imaging to guide WLL.4Via G. Lichtenstein D. Mojoli F. et al.Whole lung lavage: a unique model for ultrasound assessment of lung aeration changes.Intensive Care Med. 2010; 36: 999-1007Crossref PubMed Scopus (62) Google Scholar,5Ramachandran P. Chaudhury A. Devaraj U. Maheshwari K.U. D’Souza G. Monitoring whole-lung lavage using lung ultrasound: the changing phases of the lung.Lung India. 2018; 35: 350-353Crossref PubMed Scopus (1) Google Scholar Instillation of normal saline solution into the lung led to the ultrasonographic transition from B-lines to a full alveolar consolidation (atelectasis) (Video 3). The leading edge of this transition is hyperechoic due to a large difference in acoustic impedance and is referred to as the “shred sign.”6Touw H.R. Tuinman P.R. Gelissen H.P. Lust E. Elbers P.W. Lung ultrasound: routine practice for the next generation of internists.Neth J Med. 2015; 73: 100-107PubMed Google Scholar Alveolar consolidation can also occur as a result of external compression from pleural effusion. The atelectatic lung and effusion allow propagation of ultrasound waves such that the thoracic spine can be visualized, called the “spine sign.” Plethysmographic estimation of functional residual capacity may be used to determine instillation volumes. However, the most common approach uses 1-L aliquots for each round of lavage; this large-volume lavage may lead to unintended consequences such as overdistention and hydropneumothorax. We use dynamic lung ultrasound imaging to monitor lung deflation produced by the instillation of fluid and identify early any complication related to this step. This may reduce lung stress and optimize clearance of proteinaceous material. Lung ultrasound imaging can also be used to investigate fluid volume losses, such as leakage into the ipsilateral pleural space or contralateral lung. These suggested benefits should be studied further. At the end of each lavage cycle, reinflation of the lung is required. This is traditionally accomplished by the delivery of progressively increased tidal volumes and positive end-expiratory pressure. We use lung ultrasound imaging to guide this process in an effort to reduce volutrauma and barotrauma secondary to overinflation. The consolidated lung gradually disappears and is replaced by B-lines while manual positive ventilation is applied (Video 4). Use of POCUS to guide recruitment maneuvers in pediatric surgery patients with atelectatic lung has also been reported recently.7Sun L. Wu L. Zhang K. et al.Lung ultrasound evaluation of incremental PEEP recruitment maneuver in children undergoing cardiac surgery.Pediatr Pulmonol. 2020; 55: 1273-1281Crossref PubMed Scopus (4) Google Scholar,8Wu L. Hou Q. Bai J. et al.Modified lung ultrasound examinations in assessment and monitoring of positive end-expiratory pressure-induced lung reaeration in young children with congenital heart disease under general anesthesia.Pediatr Crit Care Med. 2019; 20: 442-449Crossref PubMed Scopus (5) Google Scholar We also perform a bilateral lung ultrasound examination prior to extubation and discharge from the recovery room. This confirms lung sliding or B-lines (rule-out pneumothorax) and identifies residual atelectasis or effusion that may need intervention. A narration of the Video 1, Video 2, Video 3, Video 4 is also provided (Narration Video). Lung ultrasound imaging is a fairly easy and efficient modality to monitor instillation volumes, to control ventilation, to ensure adequate pulmonary recruitment, and to identify complications related to WLL. We now routinely use POCUS during single and bilateral WLL with the intended benefit of reducing lung stress and reintubation risk. 1.B-lines are expected in interstitial pulmonary processes and are found in patients with PAP.2.Instillation of normal saline solution into an aerated lung will lead to the ultrasonographic transition from B-lines to atelectatic lung.3.The hyperechoic line depicting the interface between ventilated lung and atelectatic fluid-filled lung is called the “shred sign.”4.Lung ultrasound imaging may guide a more controlled and adequate lung recruitment at the end of WLL. Financial/nonfinancial disclosures: None declared. Other contributions: CHEST worked with the authors to ensure that the Journal policies on patient consent to report information were met. Due to current COVID-19 pandemic patient cannot provide written signature as physical appointments in the institution have been cancelled and patient does not have a fax machine. Additional Information: The Videos can be found in the Supplemental Materials section of the online article. To analyze this case with the videos, see the online version of this article. https://journal.chestnet.org/cms/asset/2cf632f4-7478-49a7-bdf5-a8f2b687619c/mmc1.mp4Loading ... Download .mp4 (70.43 MB) Help with .mp4 files Video 1Instillation of normal saline solution for whole lung lavage. The lung ultrasound scan was performed with a phased-array probe. The cardiac preset is used to display the image with the pointer towards the right of the screen. A smooth pleural line and diffuse B-lines are both observed throughout the lung parenchyma. As instillation of normal saline solution starts, a consolidation area appears in the most dependent and caudal area of the lung (right field of the screen). In this evolving transition area, a shred sign is observed. At the end of the fluid instillation, the aorta and vertebral bodies are seen clearly in the inferior area of the screen, the latter called the “spine sign.” There is full lung parenchyma atelectasis at the end of instillation.https://journal.chestnet.org/cms/asset/c7f650bd-a230-4efb-9437-b1f773aa2905/mmc2.mp4Loading ... Download .mp4 (41.11 MB) Help with .mp4 files Video 2Lung recruitment after whole lung lavage. A full atelectatic lung area is observed that represents the left lower pulmonary lobe. As manual ventilation is provided by the anesthesiologist, B-lines start appearing in the most central and cephalad areas of the lung (left inferior border of the screen). The area of B-lines progresses towards the periphery (upper part of the screen), decreasing the size the of previously consolidated and atelectatic lung. Because there is still minimal residual normal saline solution in the alveoli despite the recruitment maneuvers, diffuse B-lines will still be present. The diaphragm and the spleen are observed at the end of the clip on the right side of the screen.https://journal.chestnet.org/cms/asset/9aa61dd6-2ec1-4753-80f5-dafe721c7e5c/mmc3.mp4Loading ... Download .mp4 (25.45 MB) Help with .mp4 files Video 3Instillation of normal saline solution for whole lung lavage, 3x speed with notations.https://journal.chestnet.org/cms/asset/2e869256-011b-43a2-9cd1-c77305e5bd61/mmc4.mp4Loading ... Download .mp4 (13.56 MB) Help with .mp4 files Video 4Lung recruitment after whole lung lavage, 3x speed with notations.https://journal.chestnet.org/cms/asset/8d5328a6-2b8c-452c-9f78-8202606c2b1e/mmc5.mp4Loading ... Download .mp4 (14.36 MB) Help with .mp4 files Video 5