Morning Report 8/31/22

This week, second-year fellow Elen Gusman presented a case of non-expanding lung (NEL) which presented as a post-thoracentesis hydropneumothorax. Ouch!

Representative clip of a right-sided hydropneumothorax

 

What are 3 causes of NEL?

  • Endobronchial lesion –> lobar collapse
  • Chronic atelectasis
  • Trapped lung

What is trapped lung?

  • A commonly encountered cause of non-expandable lung (NEL)
  • Fibrinous, restrictive layer on visceral pleura
  • Caused by remote inflammatory pleural process
  • Often p/w chronic pleural effusion (ex vacuo physiology)

When to suspect trapped lung?

  • Chronic/recurrent effusion
  • Pain with thoracentesis
  • CT with visceral pleural thickening & loculations
  • Fluid characteristics: low LDH, protein in exudative range, paucicellular & mononuclear

How do we diagnose?

  • Gold standard is pleural manometry & elastance
  • Pel = change in pleural pressure [CWP] / volume fluid removed [L]
  • 14-25 CWP/L associated with trapped lung

Below is a YouTube video walking through three commonly utilized methods of transducing pleural pressure:

Lung ultrasound (LUS) may also predict trapped lung with an absent “sinusoid sign”

How to obtain:

  1. 2D mode U/S with indicator oriented towards head
  2. Switch to M mode with indicator through effusion into atelectatic lung
  3. Assess for respirophasic variation in position of atelectatic lung (sinusoidal pattern)

How to distinguish trapped lung from lung entrapment?

  • Entrapment – active disease, exudative effusion, directly restricts expansion
  • Trapped – chronic disease, transudative (except protein) effusion, visceral pleural thickening restricts

 

StatPearls 2022 “Trapped Lung” (link)

Annals ATS 2019;16(4):506-508. (link)

Semin Respir Crit Care Med 2001;22(6):631-6. (link)