Sonographic assessment of the diaphragm
Dr. John Wrightson
Oxford University Hospitals
NHS Foundation Trust
Headley Way
Oxford OX3 9DU
UNITED KINGDOM
[email protected]
AIMS
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To revise the anatomy and physiology of the diaphragm
To discuss the use of ultrasound in assessing
o
Structural abnormalities affecting the diaphragm
o
Features suggesting malignancy
o Diaphragmatic function, to include methods for assessment and use of B/2D
mode and M mode
To use real-life cases to illustrate the presentation
SUMMARY
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The session starts by discussing normal diaphragm anatomy and physiology
An overview is presented of the various disorders that can affect diaphragm structure
and function
Diaphragmatic herniae, including congenital diaphragmatic defects, Morgagni and
Bochdalek herniae are discussed
Subsequently, we cover functional assessment, including diaphragmatic excursion
and thickening and evidence is presented
The use of ultrasound in the ICU for diaphragmatic assessment and its role in
predicting weaning failure is discussed
Subsequently, criteria for diagnosing likely pleural malignancy are addressed, with
relevance to the diaphragm
Notes
Anatomy and physiology
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Fatigue-resistant slow-twitch type I and fast-twitch type IIa myofibres
4 components
o Central fibrous tendon (from anterior transverse septum) – no bony
attachment
o Lateral muscular walls – insert into central tendon
 Costosternal muscle – xiphoid process and upper margin lower 6 ribs
 Crural muscle – ventral and lateral aspect of lumbar vertebrae and
from arcuate ligaments
o Pleuroperitoneal folds
o Oesophageal mesentery
Movement
o Causes 75% of the increase in lung volume during quiet inspiration
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o Right dome 1.9cm more cephalad than left at end expiration
o Greatest movement in middle and posterior third
Innervation
o Phrenic nerve – C3,4,5
OpenStax - https://cnx.org/contents/[email protected]:fEI3C8Ot@10/Preface
Disorders affecting diaphragmatic function
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Neurological
o Brain
 Multiple sclerosis
 Stroke
 Arnold-Chiari malformation
o Spinal cord
 Quadriplegia
 Amyotrophic lateral sclerosis
 Poliomyelitis
 Spinal muscular atrophy
 Syringomyelia
o Phrenic nerve
 Guillain-Barré syndrome
 Tumour compression
 Neuralgic neuropathy
 Critical illness polyneuropathy
 Chronic inflammatory demyelinating polyneuropathy
 Charcot-Marie-Tooth disease
 Idiopathic
o Neuromuscular junction
 Myasthenia gravis
 Lambert-Eaton syndrome
o
o
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Muscle
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Lung
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Botulism
Organophosphates
Drugs
Pleural thickening/fluid
Herniae
Eventration
Tumour invasion
Intra-abdominal pathology
Muscular dystrophies
Myositis (infectious, inflammatory, metabolic)
Acid maltase deficiency
Glucocorticoids
Disuse atrophy
Tumour/parenchymal disorder
Hyperinflation (COPD, asthma)
Technique of sonography – general points
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Challenging in health
Patient position
Sonographic windows
o Posterior
o Lateral
o Anterior
Appearance
o 3 or 5 layers
o Alternating hyperechoic (fibro-adipose septae) and hypoechoic (muscle)
layers
Probe
o Anatomical and excursion assessment – 3.5-5 MHz curvilinear
o Thickening assessment – 7-10 MHz linear
Diaphragmatic herniae
OpenStax - https://cnx.org/contents/[email protected]:fEI3C8Ot@10/Preface
Functional evaluation
Evaluation using fluoroscopy
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Deep inspiration
Sniff test
Unilateral weakness features;
o Elevation of paralysed hemidiaphragm
o Decreased, absent or paradoxical motion during quiet respiration
o Contralateral mediastinal shift during inspiration
o Paradoxical motion under load e.g. sniff
Evaluation using ultrasound
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Good interobserver reproducibility
o Boussuges et al., Chest 2009
Agreement with fluoroscopy, higher sensitivity
o Houston et al., Clin Radiol 1995
o McCauley & Labib, Radiology 1984
Advantages
o Bedside/ICU
o Speed
o Non-ionising
o Repeatability
o Anatomical information
Assess
o Anatomy
o Excursion
o Thickening
Measurement of excursion
o B and M mode measurement
 Orient so movement is towards probe
 Posterior muscle rather than dome
o Supine
 Longitudinal or transverse
 Liver or spleen as acoustic window
 Subxyphoid longitudinal in slender adults
 Simultaneously assess both hemidiaphragms
o Quiet breathing, deep inspiration, sniff test
o M mode assessment, reference ranges
 Right, n=195
Variables
Men, cm
Women,cm
Quiet breathing
1.1-2.5
1.0-2.2
Voluntary sniffing
1.8-4.4
1.6-3.6
Deep breathing
4.7-9.2
3.6-7.7
Men, cm
Women,cm
5th to 95th percentile
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Left, n=45
Variables
Quiet breathing
1.0-2.6
0.9-2.4
Voluntary sniffing
1.9-4.3
1.7-3.7
Deep breathing
5.6-9.3
4.3-8.4
5th to 95th percentile
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 Boussuges et al., Chest 2009
Measurement of thickening
o Surrogate for shortening
o B mode
 Thickening in Zone of Apposition (ZOA)
 Supine
 7.5MHz, MAL, 8/9 ICS
o Thickening fraction (TF)
tdiTLC – tdiFRC
tdiFRC
 Care – some authors use RV instead of FRC
o Evidence
 Cohn et al., J Appl Physiol 1997
 RV to TLC, glottis open
 Supine, measured on right
 Mean increase in tdi between RV and TLC is 54% (range 42–
78%), n=9
 Autopsy study confirms sonographic findings, n=26
 Gottesman & McCool, ARJCCM 1997, n=30
 Diaphragmatic paralysis when
o TF < 0.2
o tdiFRC < 2mm
 Boon et al., Muscle Nerve 2013, n=150
 Normal values
o tdiFRC ≥ 1.5mm
o tdiFRC side to side ≤3.3mm
o TF ≥ 0.2
 Carrillo-Esper et al., Resp Care 2016, n=109
 tdiFRC
o Combined
1.5-1.7mm 95% CI
o Women 1.3-1.5mm 95% CI
o Men
1.7-2.0mm 95% CI
 Summerhill et al., Chest 2008
 TF can monitor recovery from diaphragmatic paralysis
 tdi affected by
 Body weight and height
o McCool et al., ARJCCM 1997
 Muscularity and nutritional state
o Arora & Rochester, JAPREEP 1982
ICU diaphragm dysfunction
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Dysfunction in 29-63% medical critical care patients
o Kim et al., CCM 2011
o Dres et al., AJRCCM 2016
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Due to disruption of myofibrils, neuropathy
o Disuse
o Post surgery
o COPD
o Metabolic, neuromuscular, sepsis
 Thickness decreases by 6-7.5% per day of mechanical ventilation
o Grosu et al., Chest 2012
o Zambon et al., Crit Care Med 2016
 Assessment depends on ventilation mode and PEEP
o Thickening fraction affected less than excursion
 Predictive factors for successful weaning
o Mayo et al., ICM 2016
Measurement
Value
Utilty
Excursion during SBT
< 11mm
Increased likelihood of SBT failure
Best excursion on R or L
> 25mm
Increased likelihood of SBT success
TF during SBT
> 30-36%
Increased likelihood of SBT success
R and L excursion
Bilateral absence
of excursion
Increased likelihood of SBT failure
SBT – spontaneous breathing trial
Diagnosis of malignant pleural effusion
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Qureshi et al., Thorax 2008
n
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Ultrasound
Qureshi et al.
CT
Leung et al.
52
74
Sens
Spec
Sens
Spec
Parietal pleural thickening >1cm
42%
95%
56%
88%
Nodular pleural thickening
42%
100%
36%
85%
Visceral pleural thickening
15%
100%
N/A
N/A
Diaphragmatic thickening >7mm
42%
95%
N/A
N/A
Diaphragmatic layers resolved
30%
95%
N/A
N/A
Diaphragmatic nodules
30%
100%
N/A
N/A
Overall
79%
100%
72%
83%
Pseudo-paralysis
o Large effusion causes diaphragmatic inversion
o Diaphragm contraction causes paradoxical movement (upwards), mimicking
paralysis
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