Ultrasound Lung Comets Research Articles

SP0179 Ultrasound in Lung Fibrosis

Promising data have recently been obtained by lung ultrasound (LUS), which allows the detection of pulmonary fibrosis by the evaluation of B-lines (previously called ultrasound lung comets). B-lines are the...

Acute high-altitude exposure reduces lung diffusion: Data from the HIGHCARE Alps project

The causes and development of lung fluid, as well as the integrity of the alveolar-capillary membrane at high altitude, are undefined. This study was conceived to see whether fluid accumulates within the lung with acute high altitude exposure, and whether this is associated with alveolar capillary membrane damage. We studied lung carbon monoxide diffusion (DLCO), its components – membrane diffusion (DM) and capillary volume (VC) and alveolar volume (VA) measured in 43 healthy subjects in Milan (122m) and after 1 and 3 days at Capanna Regina Margherita (4559m). DLCO measurement was adjusted for hemoglobin and inspired oxygen. We also measured plasma surfactant derived protein B (SPB) and Receptor of Advanced Glycation End-products (RAGE) as markers of alveolar-capillary membrane damage, and ultrasound lung comets as a marker of extravascular lung water. 21 subjects received acetazolamide and 22 placebo.DLCO was lower at Capanna Regina Margherita (day 1: 24.3±4.7 and day 3: 23.6±5.4mL/mmHg/min), than in Milan (25.8±5.5; p<0.001 vs. day 1 and 3) due to DM reduction (Milan: 50.5±14.6mL/mmHg/min, Capanna Regina Margherita day 1: 45.1±11.5mL/mmHg/min, day 3: 43.2±13.9mL/mmHg/min; p<0.05 Milan vs. day 3) with a partially compensatory VC increase (Milan: 96±37mL, Capanna Regina Margherita day 1: 152±66mL, day 3: 153±59mL; p<0.001 Milan vs. day 1 and day 3). Acetazolamide did not prevent the fall in DLCO albeit, between day 1 and 3, such a trend was observed. Regardless of treatment lung comets increased from 0 to 7.2±3.6 (p<0.0001). SPB and RAGE were unchanged. Lung fluid increased at high altitude without evidence from plasma measurements, supporting alveolar-capillary damage.

Lung fluid regulation at high‐altitude

BackgroundWhether lung fluid accumulates in acclimating individuals at high altitude (HA) remains controversial.PurposeTo assess the effect of HA on lung fluid regulation.Methods/ResultsSystolic pulmonary artery pressure (sPAP) (echo), lung diffusing capacity for CO (DLCO), pulmonary capillary blood volume (Vc), alveolar‐capillary conductance (Dm) (single breath method), ultrasound lung comets (ULCs) and pulmonary function (PFTs) were assessed in 8 healthy adults at sea‐level and after 1 and 9 days at Mt. Everest Base Camp (EBC), Nepal (5150 m). Also, after 5 days at EBC, DLCO and PFTs were assessed in 5 subjects pre‐and post‐acute albuterol administration. EBC was reached after an 8 d hike at progressively increasing altitudes starting at 2800 m. Altitude exposure increased sPAP, had no effect on DLCO, increased Dm and decreased Vc with a subsequent increase in Dm/Vc, and decreased the number of ULCs (Table 1). There was no change in FVC or FEV1 but an increase in MEF50. Albuterol administration increased PEF (11.85±1.52 vs. 12.40±1.45 L/s) and MEF50 (4.85±0.77 vs. 6.00±1.30 L/s) but had no effect on DLCO, Dm or Dm/Vc.ConclusionThese data suggest that lung fluid is decreased in acclimating healthy humans at high altitude.Funding:Mayo Clinic &amp; The North Face.

Beyond Belief

Beyond Belief

Feasibility of Remote Real-Time Guidance of a Cardiac Examination Performed by Novices Using a Pocket-Sized Ultrasound Device

Background. The potential of pocket-sized ultrasound devices (PUDs) to improve global healthcare delivery is limited by the lack of a suitable imaging protocol and trained users. Therefore, we investigated the feasibility of performing a brief, evidence-based cardiac limited ultrasound exam (CLUE) through wireless guidance of novice users. Methods. Three trainees applied PUDs on 27 subjects while directed by an off-site cardiologist to obtain a CLUE to screen for LV systolic dysfunction (LVSD), LA enlargement (LAE), ultrasound lung comets (ULC+), and elevated CVP (eCVP). Real-time remote audiovisual guidance and interpretation by the cardiologist were performed using the iPhone 4/iPod (FaceTime, Apple, Inc.) attached to the PUD and transmitted data wirelessly. Accuracy and technical quality of transmitted images were compared to on-site, gold-standard echo thresholds. Results. Novice versus sonographer imaging yielded technically adequate views in 122/135 (90%) versus 130/135 (96%) (P < 0.05). CLUE's combined SN, SP, and ACC were 0.67, 0.96, and 0.90. Technical adequacy (%) and accuracy for each abnormality (n) were LVSD (85%, 0.93, n = 5), LAE (89%, 0.74, n = 16), ULC+ (100%, 0.94, n = 5), and eCVP (78%, 0.91, n = 1). Conclusion. A novice can perform the CLUE using PUD when wirelessly guided by an expert. This method could facilitate PUD use for off-site bedside medical decision making and triaging of patients.

Comparison and Reproducibility of Techniques for Fluid Status Assessment in Chronic Hemodialysis Patients

Background: Several methods have been developed to assess the hydration status in chronic hemodialysis (HD) patients. The aim of this study was to compare body bioimpedance spectroscopy (BIS) with ultrasound (US) lung comet score (ULCs), B-type natriuretic peptide (BNP) and inferior vena cava diameter (IVCD) by US for the estimation of dry weight before and after HD and to analyze all methods in terms of fluid status variations induced by HD. An additional aim of this study was to establish the interoperator reproducibility of these methods. Methods: Two nephrologists evaluated BIS, ULCs, IVCD during inspiration (min) and expiration (max), the inferior vena cava collapsibility index (IVCCI) as well as BNP before and after HD in 30 patients. The same operators measured BIS, ULCs and IVCD in 28 HD patients in a blinded fashion. Results: There was a significant reduction in BIS, ULCs, IVCD and BNP after HD (p < 0.001), but a less significant reduction in IVCCI (p = 0.13). There was a significant correlation between BIS and ULCs, BNP and indexed IVCD (IVCDi)min (p < 0.05) before and after HD, and between BIS and IVCDimax only before HD. Conclusion: All methods were able to describe hyperhydration before and after HD, except for IVCCI after HD. All techniques correlated with BIS before HD. After HD, ULCs correlated better with BIS than IVCD in terms of evaluation of fluid status. It could be expected that the ULCs can give a real-time evaluation of interstitial water. The reproducibility of the measurement of BIS, IVCD and ULCs between the two operators was high.

Time course of asymptomatic interstitial pulmonary oedema at high altitude

The time course of asymptomatic pulmonary oedema during high-altitude exposure and its potential relationship with changes in cardiac function remain to clarify.Eleven volunteers were rapidly exposed to 4350m during a 4-day period. Each subject received clinical examination and thoracic ultrasonography to assess ultrasound lung comets (USLC) on day 1, 2 and 3 after arrival. Echocardiography was performed on day 2 and 4 at 4350m.All subjects had a significant increase in the number of USLC on day 1 (n=8±3), day 2 (n=7±4) and day 3 (n=3±2) compared to sea level (n=1±1) (P<0.01). Although left ventricle diastolic function and systolic tricuspid regurgitation gradient were significantly different at altitude compared to sea level, they did not correlate with the number of USLC (P>0.05).Asymptomatic pulmonary oedema seems to be transiently present in fast-ascending recreational climbers. The lack of correlation between the number of USLC and indices of cardiac changes suggest that non-cardiogenic mechanisms may underlie this transient increase in lung water.

Ultrasound lung comets: the shape of lung water

Ultrasound lung comets: the shape of lung water

241 Echocardiographic Assessment of Myocardial Performance in Response to High Altitude and Development of Subclinical Pulmonary Edema in Healthy Climbers

Despite a known association with increased pulmonary artery pressure (PAP), the pathophysiology of high-altitude pulmonary edema (HAPE) remains incompletely understood. Data regarding the impact of high altitude on left and right heart functions are sparse and conflicting. No single parameter has been validated to predict the development of HAPE among recreational climbers. We aimed to assess, by echocardiography, the right and left ventricular responses to high-altitude-induced hypoxia and to detect the occurrence of subclinical pulmonary edema. This observational study included 14 healthy subjects (8 men ; ages 27-65 years old) participating in a trekking expedition in the Everest Valley, Nepal. Echocardiography, using a portable unltrasound system (Vivid I, GE Healthcare), including the assessment of right ventricular performance parameters, was performed in Montréal (30 meters above sea level), Namche Bazar, Nepal (3450m) and Chhukkung (4730m). Lung ultrasound was performed to detect the appearance of ultrasound lung comets (ULCs) suggestive of subclinical pulmonary edema, quantified by a previously validated ULC score integrating the extent and severity of lung comets. Symptoms of high altitude sickness were assessed via the validated Lake Louise Questionnaire (LLQ). At high altitude, ULCs were seen in all except one of the subjects, with ULC scores ranging from 0 to 18 at 4730m (Fig. 1). None of the subjects had clinical criteria for HAPE. Systolic PAP increased in all subjects between Montréal and Chhukkung (mean PAP 27.4 +/− 5.4 mmHg vs. 39.3 +/− 7.7 mmHg respectively; p<0.001). Right ventricular myocardial performance index (MPI; Tei index), assessed by the pulsed-wave doppler method, increased with rising altitude (0.32 +/− 0.08 at 30m vs. 0.41 +/− 0.10 at 4730m; p=0.046). The right ventricular parameters S' and Tricuspid Annular Plane Systolic Excursion (TAPSE) remained unchanged, as did the left ventricular E/A ratio suggesting no significant change in left ventricular diastolic function. Heart rate and cardiac output increased in every subject at high altitude. No correlation could be drawn between PAP increment and MPI, MPI and ULC score, and MPI and LLQ score. Subclinical high-altitude pulmonary edema is frequent in healthy climbers living at low altitude. Right ventricular MPI increases at high altitude, and does not seem to be correlated to the magnitude of PAP increment. Whether rising MPI is a physiologic adaptive mechanism to high-altitude hypoxia or a pathologic response identifying HAPE-susceptible subjects needs to be further determined.

Lung ultrasound for the screening of interstitial lung disease in very early systemic sclerosis

BackgroundA high percentage of patients with systemic sclerosis (SSc) develop interstitial lung disease (ILD) during the course of the disease. Promising data have recently shown that lung ultrasound (LUS) is...

Realization of a poro-elastic ultrasound replica of pulmonary tissue.

In this work we describe the fabrication of a biocompatible hydrophilic scaffold composed of cross-linked gelatin that mimics the porous three-dimensional structure of pulmonary tissue as well as its water content and mechanical properties. The lung replica also reproduces the characteristic sonographic signs of pulmonary interstitial syndrome, the B-lines or ultrasound lung comets.

Lung ultrasound imaging of H1N1 influenza

We describe the case of a 8 year-old child with acute respiratory distress syndrome (ARDS) during H1N1 swine flu. Lung ultrasound performed at the time of admission showed a typical ARDS ultrasound pattern, with multiple sonographic signs of interstitial oedema (also known as B-lines or ultrasound lung comets), and diffuse bilateral sub-pleural lung consolidations. After five days of anti-viral therapy, lung ultrasound showed a reduction of the dimension of consolidations, not clearly visible at chest X-ray, helping in the management of the patient.

Ultrasound lung comets: new echographic sign of lung interstitial fibrosis in systemic sclerosis

Interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH) are common complications of systemic sclerosis (SSc). Echocardiography evaluates PAH, and chest sonography detects even mild ILC as ultrasound lung comets (ULC), i.e. multiple comet-tails fanning out from the lung surface and originating from subpleural interlobular septa thickened by fibrosis. to assess ILaD and PAH by integrated cardiac and chest ultrasound in SSc. We enrolled 30 consecutive SSc patients (age= 54+/-13 years, 23 females) in the Rheumatology Clinic of Pisa University. In all, we assessed systolic pulmonary arterial pressure (SPAP), from maximal velocity of tricuspid regurgitation flow, and ULC score with chest sonography (summing the number of ULC from each scanning space of anterior and posterior right and left chest, from second to fifth intercostal space). All patients underwent plasma assay for anti-topoisomerase antibodies (anti-Scl70), and antiicentromere associated with development of pulmonary involvement. Twenty-eight patients also underwent high resolution computed tomography, HRCT (from 0= no fibrosis to 3= honey combing). ULC number - but not SPAP - was correlated to HRCT fibrosis and presence Scl-70 antibodies. ULC number was similar in localized or diffuse forms (16+/-20 vs 21+/-19, p=ns) and was unrelated to SPAP (r=0.216, p=ns). Chest sonography assessment and ULC allow a complete, simple, radiation-free characterization of interstitial lung involvement in SSc - all in one setting and with the same instrument, same transducer and the same sonographer. In particular, ULC number is associated with HRCT evidence of lung fibrosis and presence of Scl-70 antibodies.

Ultrasound lung comets induced by repeated breath‐hold diving, a study in underwater fishermen

Pulmonary edema has been reported in breath-hold divers during fish-catching diving activity. The present study was designed to detect possible increases in extravascular lung water (EVLW) in underwater fishermen after a competition. Thirty healthy subjects were studied. They participated in two different 5-h fish-catching diving competitions: one organized in the winter (10 subjects) and one organized in the autumn (20 subjects). A questionnaire was used to record underwater activity and note respiratory problems. An increase in EVLW was investigated from the detection of ultrasound lung comets (ULC) by chest ultrasonography. Complementary investigations included echocardiography and pulmonary function testing. An increase in EVLW was detected in three out of 30 underwater fishermen after the competition. No signs of cardiovascular dysfunction were found in the entire population and in divers with an increase in the ULC score. Two divers with raised ULC presented respiratory disorders such as cough or shortness of breath. Impairment in spirometric parameters was recorded in these subjects. An increase in EVLW could be observed after a fish-catching diving competition in three out of 30 underwater fishermen. In two subjects, it was related to respiratory disorders and impairment in pulmonary flow.

Intrathoracic Impedance and Ultrasound Lung Comets in Heart Failure Deterioration Monitoring

Echographic examination of the lung surface may reveal multiple ultrasound lung comets (ULCs) originating from water-thickened interlobular septa. These images were demonstrated to be useful for noninvasive assessment of interstitial pulmonary edema. Similarly, the correlation between implantable defibrillator-measured intrathoracic impedance and pulmonary capillary wedge pressure (PCWP) was demonstrated in heart failure (HF) patients. The aims of this analysis were to assess the agreement between defibrillator-detected impedance decrease and the presence of ULCs, as well as to compare the performance of the impedance-detection algorithm and the ULCs assessment in predicting HF worsening. We studied 23 HF patients implanted with a defibrillator capable of intrathoracic impedance measurement and alerting for fluid accumulation diagnosis. At regular follow-up and at visits for HF decompensation or device alert, clinical status was assessed, chest ultrasound was performed, and PCWP was noninvasively estimated with Doppler echocardiography. During 23 ± 11 months of follow-up, 45 paired assessments of defibrillator-measured intrathoracic impedance and ULCs were performed. The number of ULCs resulted significantly correlated to the paired PCWP estimations (r = 0.917, P < 0.001) and to the impedance fluid index (r = 0.669, P < 0.001). During follow-up, 12 episodes of HF decompensation were reported in 12 patients. The impedance alert detected clinical HF deterioration with 92% sensitivity and 69% positive predictive value. The presence of ≥5 ULCs showed 83% sensitivity and 91% positive predictive value. These data demonstrate the correlation between intrathoracic impedance and the number of ULCs at chest ultrasound, and a good agreement between the defibrillator warning for fluid index and the detection of multiple ULCs.

A No-Decompression Air Dive and Ultrasound Lung Comets

Increased accumulation of extravascular lung water after repetitive deep trimix dives was recently reported. This effect was evident 40 min post-dive, but in subsequent studies most signs of this lung congestion were not evident 2-3 h post-dive, indicating no major negative effects on respiratory gas exchange following deep dives. Whether this response is unique for trimix dives or also occurs in more frequent air dives is presently unknown. A single no-decompression field dive to 33 m with 20 min bottom time was performed by 12 male divers. Multiple ultrasound lung comets (ULC), bubble grade (BG), and single-breath lung diffusing capacity (DLCO) measurements were made before and up to 120 min after the dive. Median BG was rather high with maximal values observed at 40 min post-dive [median 4 (4-4)]. Arterialization of bubbles from the venous side was observed only in one diver lasting up to 60 min post-dive. Despite high BG, no DCS symptoms were noted. DLCO and ULC were unchanged after the dive at any time point (DLCO(corr) was 33.6 +/- 1.9 ml x min(-1) mmHg(-1) pre-dive, 32.7 +/- 3.8 ml x min(-1) x mmHg(-1) at 60 min post-dive, and 33.2 +/- 5.3 ml x min(-1) x mmHg(-1) at 120 min post-dive; ULC count was 4.1 +/- 1.9 pre-dive, 4.9 +/- 3.3 at 20 min post-dive, and 3.3 +/- 1.9 at 60 min post-dive. These preliminary findings show no evidence of increased accumulation of extravascular lung water in male divers after a single no-decompression air dive at the limits of accepted Norwegian diving tables.

Comparison of Prognostic Value of Echocardiacgraphic Risk Score With the Thrombolysis In Myocardial Infarction (TIMI) and Global Registry In Acute Coronary Events (GRACE) Risk Scores in Acute Coronary Syndrome

Risk stratification in patients with acute coronary syndromes (ACS) is achieved today by clinical models, "blind" to the prognostic support of imaging methods. To assess the value of simple at rest cardiac chest sonography in predicting the intra- and extrahospital risk of death or myocardial infarction, we enrolled 470 consecutive in-patients (312 men, age 71 ± 12 years) who had been admitted for ACS. On admission, all had received a clinical score using the Global Registry in Acute Coronary Events and Thrombolysis in Myocardial Infarction systems and, within 1 to 12 hours, a comprehensive cardiac-chest ultrasound scan. Each of the 16 echocardiographic parameters evaluating left and right, systolic and diastolic, ventricular function and structure, was scored from 0 (normal) to 3 (severely abnormal). The median follow-up was 5 months (interquartile range 1 to 10). Patients with hard events (n = 102) could be separated from patients without events (n = 368) using the Global Registry in Acute Coronary Events score, Thrombolysis in Myocardial Infarction score, and several echocardiographic parameters. On multivariate Cox analysis, ejection fraction (hazard ratio 1.45, 95% confidence interval 1.02 to 2.08, p = 0.040), tricuspid annular plane systolic excursion (hazard ratio 1.66, 95% confidence interval 1.13 to 2.45, p = 0.010) and ultrasound lung comets (hazard ratio 1.69, 95% confidence interval 1.25 to 2.27, p = 0.001) were independent predictors of cardiac events. The 3-variable echocardiographic score (from 0, normal to 9, severe abnormalities in ejection fraction, ultrasound lung comets, and tricuspid annular plane systolic excursion) effectively stratified patients and added value (hazard ratio 2.52, 95% confidence interval 1.89 to 3.37, p <0.0001) to the Global Registry in Acute Coronary Events score (hazard ratio 1.60, 95% confidence interval 1.07 to 2.39, p = 0.003). In conclusion, for patients with ACS, effective risk stratification can be achieved with cardiac and chest ultrasound imaging parameters, adding prognostic value to the clinical risk scores.

B-Lines Quantify the Lung Water Content: A Lung Ultrasound Versus Lung Gravimetry Study in Acute Lung Injury

B-lines (also termed ultrasound lung comets) obtained with lung ultrasound detect experimental acute lung injury (ALI) very early and before hemogasanalytic changes, with a simple, noninvasive, nonionizing and real-time method. Our aim was to estimate the correlation between B-lines number and the wet/dry ratio of the lung tissue, measured by gravimetry, in an experimental model of ALI. Seventeen Na-pentobarbital anesthetized, cannulated (central vein and carotid artery) minipigs were studied: five sham-operated animals served as controls and, in 12 animals, ALI was induced by injection of oleic acid (0.1 mL/kg) via the central venous catheter. B-lines were measured by echographic scanner in four predetermined chest scanning sites in each animal. At the end of each experiment, both lungs were dissected, weighed and dried to determine wet/dry weight ratio by gravimetry. After the injection of oleic acid, B-lines number increased over time. A significant correlation was found between the wet/dry ratio and B-lines number (r = 0.91, p < 0.001). These data suggest that in an experimental pig model of ALI/ARDS, B-lines assessed by lung ultrasound provide a simple, semiquantitative, noninvasive index of lung water accumulation, strongly correlated to invasive gravimetric assessment. (E-mail: gargani@ifc.cnr.it)

Ultrasound lung “comets” increase after breath-hold diving

The purpose of the study was to analyze the ultrasound lung comets (ULCs) variation, which are a sign of extra-vascular lung water. Forty-two healthy individuals performed breath-hold diving in different conditions: dynamic surface apnea; deep variable-weight apnea and shallow, face immersed without effort (static maximal and non-maximal). The number of ULCs was evaluated by means of an ultrasound scan of the chest, before and after breath-hold diving sessions. The ULC score increased significantly from baseline after dynamic surface apnea (p = 0.0068), after deep breath-hold sessions (p = 0.0018), and after static maximal apnea (p = 0.031). There was no statistically significant difference between the average increase of ULC scores after dynamic surface apnea and deep breath-hold diving. We, therefore, postulate that extravascular lung water accumulation may be due to other factors than (deep) immersion alone, because it occurs during dynamic surface apnea as well. Three mechanisms may be responsible for this. First, the immersion-induced hydrostatic pressure gradient applied on the body causes a shift of peripheral venous blood towards the thorax. Second, the blood pooling effect found during the diving response Redistributes blood to the pulmonary vascular bed. Third, it is possible that the intense involuntary diaphragmatic contractions occurring during the "struggle phase" of the breath-hold can also produce a blood shift from the pulmonary capillaries to the pulmonary alveoli. A combination of these factors may explain the observed increase in ULC scores in deep, shallow maximal and shallow dynamic apneas, whereas shallow non-maximal apneas seem to be not "ULC provoking".

Frequent subclinical high-altitude pulmonary edema detected by chest sonography as ultrasound lung comets in recreational climbers

The ultrasound lung comets detected by chest sonography are a simple, noninvasive, semiquantitative sign of increased extravascular lung water. The aim of this study was to evaluate, by chest sonography, the incidence of interstitial pulmonary edema in recreational high-altitude climbers. Observational study. Eighteen healthy subjects (mean age 45 +/- 10 yrs, ten males) participating in a high-altitude trek in Nepal. Chest and cardiac sonography at sea level and at different altitudes during ascent. Ultrasound lung comets were evaluated on anterior chest at 28 predefined scanning sites. At individual patient analysis, ultrasound lung comets during ascent appeared in 15 of 18 subjects (83%) at 3440 m above sea level and in 18 of 18 subjects (100%) at 4790 m above sea level in the presence of normal left and right ventricular function and pulmonary artery systolic pressure rise (sea level = 24 +/- 5 mm Hg vs. peak ascent = 42 +/- 11 mm Hg, p < .001). Ultrasound lung comets were absent at baseline (day 2, altitude 1350 m, 1.06 +/- 1.3), increased progressively during the ascent (day 14, altitude 5130 m: 16.5 +/- 8; p < .001 vs. previous steps), and decreased at descent (day 20, altitude 1355 m: 2.9 +/- 1.7; p = nonsignificant vs. baseline). An ultrasound lung comet score showed a negative correlation with O(2) saturation (R = -.7; p < .0001). In recreational climbers, chest sonography revealed a high prevalence of clinically silent interstitial pulmonary edema mirrored by decreased O(2) saturation, whereas no statistically significant relationship with pulmonary artery systolic pressure was observed during ascent.