WINFOCUS Lung Course 2019

By | 22/02/2019

BASIC LEVEL

Key referenceInternational evidence-based recommendations for point-of-care lung ultrasound.

Lung Ultrasound overview

Ultrasound whilst very useful does suffer from ideal vs reality difference. Often images obtained in real-life patients and conditions don’t reflect those seen at courses. BUT it is usually good enough.

Limitations

  • Bones of thoracic cage
    • 70% of pleura is still visible
  • Air in lung
  • Surface imaging techniques
Lesion surrounded by normal aerated lung often cannot be seen on ultrasound

Recommends scanning in 8 sectors (c.f. Lichtenstein’s BLU protocol which utilises 6 points – ref). It does depend on what you are looking for – if pneumonia, make sure you scan the posterior aspects.

Pneumothorax

Key point 1 – differentiating between air before or beyond the visceral pleura

Key point 2 – No sliding does not equal pneumothorax necessarily. Differential diagnosis includes:

  • Pleural adhesions
  • Emphysematous bullae
  • Apnoea
  • Selective intubation
  • Atelectasis
  • Pneumonia

Do you see the lung pulse?

Do you see B-lines? If B-lines are present, there is NO pneumothorax

The position of the lung point in the supine patient gives an idea of the size. If above the anterior axillary line, it is small.

Interstitial Syndrome

B-lines

  • Vertical
  • From the pleural line
  • Spreads without fade
  • Moves synchronously with lung sliding
  • Erases horizontal artifacts

Pathological – at least 3 B-lines in longitudinal scan (or at least 3 closely placed B-lines in transverse scan)

B-line generation

Where do B-lines come from?

Sonographic interstitial syndrome: the sound of lung water.

  • Increase fluid –> increase weight but constant lung volume
  • Lung deflation –> weight constant but lung volume reduces

Focal Interstitial Syndrome

  • Pneumonia
  • Atelectasis
  • Pulmonary contusion
  • Pulmonary infarction
  • Pleural disease
  • Neoplasia

Diffuse Interstitial Syndrome

  • Pulmonary oedema of various causes
  • Interstitial pneumonia
  • Diffuse parenchymal lung disease (pulmonary fibrosis, alveolar proteinosis…)
Lung US vs PA catheter and PICCO
Lung US vs BNP

Lung ultrasound integrated with clinical assessment for the diagnosis of acute decompensated heart failure in the emergency department: a randomized controlled trial

Pulmonary fibrosis

  • Irregular, fragmented pleural line
  • Small echo-poor subpleural areas
  • Irregularly spaced B-lines

ARDS

  • Anterior sub-pleural consolidation
  • Absence or reduced sliding
  • ‘Spared areas’ of normal parenchyma
  • Pleural line abnormalities (irregular thickened, fragmented pleural line)
  • Non-homogenous distribution of B-lines

Consolidation

Consolidation = fluid-filled lung

  • Subpleural
  • Tissue-like echotexture

It is a dynamic process and therefore, appearance will vary

  1. When initially fluid filled, hepaticisation
  2. Phase of lysis follows –> lentil-shaped air trapping

Pulmonary infarction

  • Early –> hypoechoic, homogeneous subpleural structure
  • Late –> margins serrated, echodence, no blood flow on colour doppler, triangular in shape

Atelectasis – absence of ventilation

  • Compression vs resorption atelectasis

Pleural effusion

CT inferior to LUS in differentiating exudate and transudate

Pleural exudates and transudates: diagnosis with contrast-enhanced CT.

Quantification – many methods exist. The gold standard remains CT.

Usefulness of ultrasonography in predicting pleural effusions > 500 mL in patients receiving mechanical ventilation.

Multiplane ultrasound approach to quantify pleural effusion at the bedside.

Thoracocentesis – Use ultrasound in real-time NOT blind NOT marking

British Thoracic Society Pleural Disease Guideline Group

Evaluation of pleuritic chest pain

Diagnosis of radio-occult pulmonary conditions by real-time chest ultrasonography in patients with pleuritic pain.

  • Ultrasound sensitivity – 94.7%
  • Ultrasound specificity – 96.7%

A comparison of different diagnostic tests in the bedside evaluation of pleuritic pain in the ED.

Chest radiography and blood tests may be inadequate in the diagnostic process of pleuritic pain. In case of silent CXR, LUS is critical for identifying patients with pleural-pulmonary radio-occult conditions at bedside and cannot be safely replaced by other conventional methods.

Volpicelli et al., 2012

Ultrasound and the airway

Check ETT position – oesophageal intubation and selective intubation

Tracheal rapid ultrasound exam (TRUE) for confirming endotracheal tube placement during emergency intubation

Auscultation versus Point-of-care Ultrasound to Determine Endotracheal versus Bronchial Intubation: A Diagnostic Accuracy Study.

Upper airway anatomy identification

Structured approach to ultrasound-guided identification of the cricothyroid membrane: a randomized comparison with the palpation method in the morbidly obese.

Predict difficult airway

Ultrasound evaluation of the airway in the ED: a feasibility study

Sublingual ultrasound as an assessment method for predicting difficult intubation: a pilot study

Ultrasound-Assisted Evaluation of the Airway in Clinical Anesthesia Practice: Past, Present and Future

Guide percutaneous tracheostomy

Putting it all together

BLUE-protocol and FALLS-protocol: two applications of lung ultrasound in the critically ill.

Advanced level

Complex Pneumothorax

Beware

  • False lung point – normal folds of pleura e.g. around the heart
  • Lung pulse cause by mammary vessels
  • Double lung point – link
  • Septated pneumothorax

Unusual new signs of pneumothorax at lung ultrasound

Using Thoracic Ultrasonography to Accurately Assess Pneumothorax Progression During Positive Pressure Ventilation

Ultrasound evaluation of diaphragm function

Sonographic evaluation of the diaphragm in critically ill patients. Technique and clinical applications.

Technique

  • Excursion –> curvilinear probe
  • Thickness –> liner probe

Besides excursion, M-mode allows for measurement of inspiratory time, expiratory time and speed of contraction

Diaphragm excursion – inter and intra observer agreement 90-95% (lower agreement on the left)

Diaphragm thickness – need to identify 3 layers (pleura, diaphragm, peritoneum)

Consolidation and differential diagnosis

Sonomorphology of pneumonia

  • Similar to liver
  • Lentil-shaped air trappings
  • Air bronchogram(s)
  • Fluid bronchogram
  • Blurred/serrated margins

Lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia: a prospective, multicenter, diagnostic accuracy study.

  • Sensitivity 94%, specificity 98%
  • With auscultation findings, increase sensitivity
  • CXR missed or was inconclusive in 7% of LUS +
  • LUS missed 8% of CAP

Ultrasound for “Lung Monitoring” of Ventilated Patients

Acute respiratory failure: BLUE protocol

Relevance of Lung Ultrasound in the Diagnosis of Acute Respiratory Failure*

Monitoring alveolar recruitment

Lung sonography is highly sensitive to variations of the pulmonary content and balance between air and fluids, like a real lung densitometer

Volpicelli. J Ultrasound 2013; 32: 165-171

When the lung decreases in air content, US shows an image with increased density

  • Acute cardiac failure – increase density, increase weight of the lung
  • Atelectasis – increase density, constant weight

Ultrasound assessment of lung aeration loss during a successful weaning trial predicts postextubation distress*.

  • Lung ultrasound score calculation
    • All intercostal space
    • Most severe US pattern characterizes that region
    • LUS is calculated from the addition of the 12 examined region

Using sonography to assess lung recruitment in patients with acute respiratory distress syndrome.

Anaesthesia-induced atelectasis

  • Well known condition observed in 68-100% of adult and pediatric pts undergoing general anaesthesia
  • Appear when lung is collapsed, more frequently in the most dependent lung zones
  • This side effect of general anaesthesia can be found in all types of interventions
  • Could be associated with postoperative pulmonary complications

Monitoring pulmonary congestion and haemodynamics

Sadly nothing on portal and venous doppler studies etc. I would refer you to the excellent www.thinkingcriticalcare.com

Take home messages from the speaker

  • LUS provide a simple, semiquantitative index of extravascular lung water (EVLW) accumulation
  • LUS strongly correlates with chest x-ray, CT scan and gravimetric studies in the evaluation of EVLW
  • LUS is an earlier index of EVLW increase in comparison to PaO2/FiO2
  • Correlation among LUS, PiCCO and Swan-Ganz vary according to different clinical features

Integrating US lung-heart-veins: pulmonary embolism

Accuracy of point-of-care multiorgan ultrasonography for the diagnosis of pulmonary embolism.

Diagnostic accuracy of lung ultrasound for pulmonary embolism: a systematic review and meta-analysis.