A-lines and B-lines: lung ultrasound as a bedside tool for predicting pulmonary artery occlusion pressure in the critically ill.

BACKGROUND The risk of pulmonary edema is the main limiting factor in fluid therapy in the critically ill. Interstitial edema is a subclinical step that precedes alveolar edema. This study assesses a bedside tool for detecting interstitial edema, lung ultrasound. The A-line is a horizontal artifact indicating a normal lung surface. The B-line is a kind of comet-tail artifact indicating subpleural interstitial edema. The relationship between anterior interstitial edema detected by lung ultrasound and the pulmonary artery occlusion pressure (PAOP) value was investigated. METHOD We performed a prospective study in medicosurgical ICUs of university-affiliated teaching hospitals. We enrolled 102 consecutive mechanically ventilated patients who all underwent pulmonary artery catheterization. We defined A-predominance as a majority of anterior A-lines and B-predominance as a majority of anterior B-lines. These patterns were correlated with PAOP. RESULTS For diagnosing PAOP <or= 13 mm Hg, A-predominance had 90% specificity, 67% sensitivity, 91% positive predictive value, and 65% negative predictive value. For diagnosing PAOP <or= 18 mm Hg, A-predominance had 93% specificity, 50% sensitivity, 97% positive predictive value, and 24% negative predictive value, respectively. CONCLUSIONS A-predominance indicates dry interlobular septa. Specific to predicting a low PAOP value, A-predominance suggests that fluid may be given without initial concern for the development of hydrostatic pulmonary edema. B-predominance indicates interstitial syndrome, which is usually related to interstitial edema. B-predominance is observed in a wide range of PAOP values, precluding conclusions about the need for fluid therapy. This bedside potential will be appreciated by those intensivists who envision fluid therapy based on low PAOP values and who consider that using the concept of a safety factor provided by lung ultrasound is logical.

[1]  A. Guyton,et al.  Textbook of Medical Physiology , 1961 .

[2]  H. E. Cohen,et al.  The bedside chest radiograph in the evaluation of incipient heart failure. , 1972, Radiology.

[3]  N. C. Staub.  Pulmonary edema. , 1974, Physiological reviews.

[4]  A. Perel,et al.  Cardiopulmonary effects of volume loading in patients in septic shock. , 1977, Annals of surgery.

[5]  J. Bourdarias,et al.  Influence of positive end-expiratory pressure on left ventricular performance. , 1981, The New England journal of medicine.

[6]  E. Rackow,et al.  Optimum left heart filling pressure during fluid resuscitation of patients with hypovolemic and septic shock , 1983, Critical care medicine.

[7]  D. Lichtenstein.  Diagnostic échographique de l'œdème pulmonaire , 1994 .

[8]  D. Lichtenstein,et al.  Appréciation non invasive de la pression veineuse centrale par la mesure échographique du calibre de la veine cave inférieure en réanimation , 1994 .

[9]  L. Goldman,et al.  The effectiveness of right heart catheterization in the initial care of critically ill patients. SUPPORT Investigators. , 1996, JAMA.

[10]  L. Goldman,et al.  The effectiveness of right heart catheterization in the initial care of critically ill patients. SUPPORT Investigators. , 1996, JAMA.

[11]  D. Lichtenstein,et al.  The comet-tail artifact. An ultrasound sign of alveolar-interstitial syndrome. , 1997, American journal of respiratory and critical care medicine.

[12]  J. Wagner,et al.  Right ventricular end-diastolic volume as a predictor of the hemodynamic response to a fluid challenge. , 1998, Chest.

[13]  D. Lichtenstein,et al.  A lung ultrasound sign allowing bedside distinction between pulmonary edema and COPD: the comet-tail artifact , 1998, Intensive Care Medicine.

[14]  G. Lebuffe,et al.  Systolic Pressure Variation as a Guide to Fluid Therapy in Patients with Sepsis‐induced Hypotension , 1998, Anesthesiology.

[15]  A. Sargsyan,et al.  Thoracic ultrasound diagnosis of pneumothorax. , 1999, The Journal of trauma.

[16]  D. Chemla,et al.  Relation between respiratory changes in arterial pulse pressure and fluid responsiveness in septic patients with acute circulatory failure. , 2000, American journal of respiratory and critical care medicine.

[17]  S. Nicolaou,et al.  Traumatic pneumothorax detection with thoracic US: correlation with chest radiography and CT--initial experience. , 2002, Radiology.

[18]  J. Achard,et al.  Changes in BP induced by passive leg raising predict response to fluid loading in critically ill patients. , 2002, Chest.

[19]  J. Teboul,et al.  Predicting fluid responsiveness in ICU patients: a critical analysis of the evidence. , 2002, Chest.

[20]  S. Dzik.  Early goal-directed therapy in the treatment of severe sepsis and septic shock , 2002 .

[21]  M. Pinsky.  Clinical significance of pulmonary artery occlusion pressure , 2003, Intensive Care Medicine.

[22]  D. Wijeysundera,et al.  Pulmonary-artery catheters in high-risk surgical patients. , 2003, The New England journal of medicine.

[23]  M. Lenoir,et al.  SARS in Northern Vietnam. , 2003, The New England journal of medicine.

[24]  C. Tribouilloy,et al.  Monitoring of respiratory variations of aortic blood flow velocity using esophageal Doppler , 2004, Intensive Care Medicine.

[25]  K. Chergui,et al.  Superior vena caval collapsibility as a gauge of volume status in ventilated septic patients , 2004, Intensive Care Medicine.

[26]  M. Pinsky.  Using ventilation-induced aortic pressure and flow variation to diagnose preload responsiveness , 2004, Intensive Care Medicine.

[27]  P. Mayo,et al.  Safety of ultrasound-guided thoracentesis in patients receiving mechanical ventilation. , 2004, Chest.

[28]  S. Magder.  How to use central venous pressure measurements , 2005, Current opinion in critical care.

[29]  G. Schüpfer,et al.  Hemodynamic monitoring utilizing transesophageal echocardiography: the relationships among pressure, flow, and function. , 2005, Chest.

[30]  M. Blaivas,et al.  A prospective comparison of supine chest radiography and bedside ultrasound for the diagnosis of traumatic pneumothorax. , 2005, Academic emergency medicine : official journal of the Society for Academic Emergency Medicine.

[31]  D. Lichtenstein,et al.  Ultrasound diagnosis of occult pneumothorax* , 2005, Critical care medicine.

[32]  A. Perel,et al.  Assessing Fluid-Responsiveness by a Standardized Ventilatory Maneuver: The Respiratory Systolic Variation Test , 2005, Anesthesia and Analgesia.

[33]  A. Zangrillo,et al.  "Ultrasound comet-tail images": a marker of pulmonary edema: a comparative study with wedge pressure and extravascular lung water. , 2005, Chest.

[34]  O. Axler,et al.  Intensive use of general ultrasound in the intensive care unit , 1993, Intensive Care Medicine.

[35]  G. Via,et al.  Echocardiographic assessment of cardiovascular failure. , 2006, Minerva anestesiologica.

[36]  G. Soldati,et al.  Chest ultrasonography in lung contusion. , 2006, Chest.

[37]  L. Cardinale,et al.  Bedside lung ultrasound in the assessment of alveolar-interstitial syndrome. , 2006, The American journal of emergency medicine.

[38]  P. Ray,et al.  Cardiac filling pressures are not appropriate to predict hemodynamic response to volume challenge* , 2007, Critical care medicine.

[39]  Ashley C. Mull.  Ultrasonography in Lung Contusion , 2007 .

[40]  D. Lichtenstein,et al.  Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. , 2008, Chest.

[41]  D. Feller-Kopman,et al.  American College of Chest Physicians/La Société de Réanimation de Langue Française statement on competence in critical care ultrasonography. , 2009, Chest.