Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5189_Библиотеки_им_академика_М_И_Перельмана.pdf
37 Pneumonia andConsolidation
Fig. 37.6 Pleural
effusion and lung
consolidation
441
Comparing Ultrasound toOther
Imaging Modalities
The diagnosis of pneumonia has often been made
in real time combining clinical history, labs, and
often x-ray imaging. It is quite clear that history,
examination, and experience are not enough to
diagnose pneumonia with any adequate sensitivity or specicity [15]. Ultrasound continues to
show improved diagnostic accuracy when compared to x-ray in multiple studies, including a
2015 meta-analysis using CT as the gold standard [16]. A systematic review in 2017 showed
that ultrasound, although not as sensitive as CT
scan, was a clinical tool which had excellent test
characteristics as well as signicantly decreased
cost and transport needs compared to CT scan.
The 95% condence interval for sensitivity was
80–90% and the specicity 70–90% [17]. These
evidence-based ndings show ultrasound to be an
important addition to patient care in patients with
consolidative pulmonary processes, especially in
critical care settings where transportation within
the hospital carries risk.
Lung Ultrasound forPneumonia
intheEra ofCOVID-19
Overall, the ndings associated with COVID-19
have been found to be similar to what is discussed
above for other forms of pneumonia but there are
some unique features to the COVID-19 pandemic
that make LUS especially appealing. The ability
to perform LUS at the bedside is especially
helpful as it removes the need for transport across
the hospital and thus minimizes exposure to
others.
As stated above, the ndings of COVID-19
pneumonia are similar overall to the ndings in
non-COVID pneumonia. There have been a signicant number of case series and small studies
during the last 2years and a variety of both systemic reviews and meta-analyses. Early in the pandemic, a systematic review and meta-analysis
demonstrated that the CT ndings of COVID-19
involved a bilateral, peripheral predominant, and
heterogeneous distribution [18]. Given the wide
area of involvement, a protocoled evaluation of
multiple lung zones is important when using point-
442
A. Foderaro and A. T. Levinson
of-care LUS. Subsequently, Castelao etal. conrmed similar ndings with LUS; however, noting
a posterior and lower lobe predominance [18, 19].
Due to the heterogeneity of location in the
lungs, as well as diversity of LUS ndings, there
were several proposals for standardization of
COVID-19 LUS.Soldati et al. proposed a LUS
score for evaluation scanning 14 zones with a
score being produced, using many of the discussed ndings for pneumonia, between 0 and 3.
This score was evaluated by Gil-Rodriguez etal.
in a 2022 systematic review of 66 articles with
pooled population of 4687 patients, which demonstrated that a higher LUS score was associated
with worse outcomes, including death and need
for ICU admission.
Pit Falls ofLung Ultrasound
As with all imaging modalities, ultrasound and
specically LUS carry some downsides. As noted
previously, one of the issues can be related to the
high number of lung zones which need to be
imaged for a complete evaluation. This brings
with it a need for patient mobilization and positioning which can be difcult, especially in hospitalized patients or those who are critically ill.
Another potential issue can be in relation to body
habitus and obesity. In obese patients, the ultrasound waves have greater distance to travel,
therefore affecting the signal-to-noise ratio,
decreasing image quality and increasing the difculty in interpretation of the images. Further
investigations into techniques and creation of
efcient protocols will be important to make
ultrasound imaging clinically practical in heterogenous patient populations.
Summary Point
• Lung ultrasound to detect alveolar consolida-
tion/pneumonia, although not as sensitive as
CT scan, is a useful clinical tool which has
excellent test characteristics.
Pro-Tips (Call-Out)
• Lung pulse is a sonographic observation of
pleural line movement corresponding to heart
beats. This nding is seen transmitted through
consolidated lung and, in addition to dynamic
air bronchograms, can be helpful in differentiating pneumonia from atelectasis.
Evolving Evidence (Call-Out)
• If the air bronchograms are moving within the
image, this is referred to as dynamic air
bronchograms and have been shown to be
specic for pneumonia as compared to atelectasis. Conversely, a static air bronchogram
can be seen in both pneumonia and
atelectasis.
References
1. Xirouchaki N, etal. Lung ultrasound in critically ill
patients: comparison with bedside chest radiography.
Intensive Care Med. 2011;37(9):1488–93.
2. Hagaman JT, et al. Admission chest radiograph lacks sensitivity in the diagnosis of community-acquired pneumonia. Am J Med Sci.
2009;337(4):236–40.
3. Lichtenstein DA.Lung ultrasound in the critically ill.
Ann Intensive Care. 2014;4(1):1–12.
4. Durant A, Nagdev A. Ultrasound detection of lung
hepatization. West J Emerg Med. 2010;11(4):322–3.
5. Biswas A, et al. The utility of the “shred sign” in
the diagnosis of acute respiratory distress syndrome
resulting from multifocal pneumonia. Am J Respir
Crit Care Med. 2017;195(2):e20–2.
6. Lichtenstein D, Mezière G, Seitz J. The dynamic
air bronchogram: a lung ultrasound sign of alveolar consolidation ruling out atelectasis. Chest.
2009;135(6):1421–5.
7. Lichtenstein DA.Lung ultrasound in the critically ill.
Ann Intensive Care. 2014;4:1.
8. Al Deeb M, Barbic S, Featherstone R, et al. Pointof- care ultrasonography for the diagnosis of acute
cardiogenic pulmonary edema in patients presenting
with acute dyspnea: a systematic review and metaanalysis. Acad Emerg Med. 2014;21:843–52.
9. Soni NJ, et al. Ultrasound in the diagnosis and
management of pleural effusions. J Hosp Med.
2015;10(12):811–6.
37 Pneumonia andConsolidation
443
10. Light RW, etal. Parapneumonic effusions. Am J Med.
1980;69(4):507–12.
11. Kearney SE, etal. Computed tomography and ultrasound in parapneumonic effusions and empyema.
Clin Radiol. 2000;55(7):542–7.
12. Metlay JP, Kapoor WN, Fine MJ.Does this patient
have community-acquired pneumonia? Diagnosing
pneumonia by history and physical examination.
JAMA. 1997;278(17):1440–5.
13. Ye X, Xiao H, Chen B, etal. Accuracy of lung ultrasonography versus chest radiography for the diagnosis of adult community-acquired pneumonia:
review of the literature and meta-analysis. PLoS One.
2015;10:e0130066.
14. Llamas-Alvarez AM, Tenza-Lozano EM, LatourPerez J. Accuracy of lung ultrasonography in the
diagnosis of pneumonia in adults: systematic review
and meta-analysis. Chest. 2017;151:374–82.
15. Bao C, etal. Coronavirus disease 2019 (COVID-19)
CT ndings: a systematic review and meta-analysis. J
Am Coll Radiol. 2020;17(6):701–9.
16. Castelao J, etal. Findings and prognostic value of lung
ultrasound in COVID-19 pneumonia. J Ultrasound
Med. 2021;40(7):1315–24.
17. Yasukawa K, Minami T, Boulware DR, Shimada
A, Fischer EA. Point-of-care lung ultrasound for
COVID-19: ndings and prognostic implications
from 105 consecutive patients. J Intensive Care Med.
2021;36(3):334–42.
18. Soldati G, etal. Proposal for international standardization of the use of lung ultrasound for patients
with COVID-19: a simple, quantitative, reproducible
method. J Ultrasound Med. 2020;39(7):1413–9.
19. Gil-Rodríguez J, et al. Ultrasound ndings of lung
ultrasonography in COVID-19: a systematic review.
Eur J Radiol. 2022;148:110156.
Diaphragm
IdunnMorris andEwanGoligher
38
Learning Objectives
1. Use ultrasound to measure diaphragm thickness, thickening, excursion, echodensity,
strain, and tissue velocity
2. Understand the caveats and limitations of
each modality of assessment and know when
and how to use them diagnostically and
prognostically
3. Be able to synthesize information obtained
from diaphragm ultrasound and apply this to a
clinical context to aid decision making
I. Morris
Interdepartmental Division of Critical Care Medicine,
University of Toronto, Toronto, ON, Canada
Division of Respirology, Department of Medicine,
University Health Network, Toronto, ON, Canada
Department of Intensive Care Medicine, Nepean
Hospital, Sydney, Australia
e-mail: idunn.morris@uhn.ca
E. Goligher (*)
Interdepartmental Division of Critical Care Medicine,
University of Toronto, Toronto, ON, Canada
Division of Respirology, Department of Medicine,
University Health Network, Toronto, ON, Canada
Toronto General Hospital Research Institute,
Toronto, ON, Canada
e-mail: ewan.goligher@utoronto.ca;
ewan.goligher@uhn.ca
Introduction
The diaphragm is the primary muscle of ventilation. It is composed of the muscular central tendon, the crural diaphragm which inserts into the
rst three lumbar vertebrae, and the costal diaphragm which inserts onto rib cage and xiphoid
process (Fig.38.1). The crural diaphragm lowers
the dome of the diaphragm while the costal diaphragm lowers the diaphragm dome and elevates
the lower rib cage. The force generated by the
action of the diaphragm is quantied as the transdiaphragmatic pressure (difference in intrathoracic and intraabdominal pressures). This force is
modied by the length of the diaphragm at the
onset of contraction (i.e., the length-tension relation) and by the rate of shortening during contraction (i.e. the force-velocity relationship).
Transdiaphragmatic pressure can be computed
from the difference in esophageal and gastric
pressures measured using an esophageal catheter
tted with esophageal and gastric balloons.
Obtaining these measurements requires specialized equipment and considerable time and technical expertise.
Diaphragm ultrasound is a comparatively
novel technique that enables non-invasive assessment of the structure and function of the right and
left hemidiaphragm. Assessment of abnormal
diaphragm structure and function by ultrasound
can aid clinical decision-making in both outpatients presenting with respiratory complaints and
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2025
M. J. Lanspa, A. T. Levinson (eds.), Echocardiography and Ultrasonography in the ICU,
Respiratory Medicine, https://doi.org/10.1007/978-3-031-80038-2_38
445
446
Fig. 38.1 Zone of
apposition: the portion
of the costal diaphragm
that lies adjacent to the
lower rib cage
throughout the entirety
of the respiratory cycle
I. Morris and E. Goligher
in hospitalized and mechanically ventilated
patients with acute or chronic respiratory failure.
Diaphragm Thickness
andEchodensity
Measurement
Diaphragm thickness (Tdi) is measured by visualizing the diaphragm in cross section using a high
resolution (10–15MHz) linear array transducer
held perpendicular to the chest wall along the
eighth, nineth, or tenth intercostal space between
the mid and anterior axillary line. The relatively
anechoic costal diaphragm is located between the
highly echogenic pleural and peritoneal membranes. The costal diaphragm covers approximately one third of the lower rib cage (zone of
apposition, Fig.38.1). Its thickness tapers from
its costal insertion to the central tendon as well as
from anterior to posterior regions. Given this
variability in thickness, to detect changes in diaphragm thickness over time, serial measurements
should be made at exactly the same location by
marking the probe position at the skin. The resting (relaxed) thickness of the muscle at endexpiration (functional residual capacity, FRC) is
taken as the diaphragm thickness (Fig.38.2). Tdi
can be measured in B mode if adequately timed
to end expiration, or this can be done more easily
in M mode. However, in M mode, doppler alignment is important so as to avoid overestimation
of T
by off-axis imaging.
di
Echodensity of the diaphragm can also be
measured in this view in B mode. The grayscale
density of pixels contained within the region of
the diaphragm muscle is quantied using image
analysis software (e.g., ImageJ, National
Institutes of Health, Bethesda MD, https://
imagej.nih.gov/ij/). Increases in echodensity in
other muscles during critical illness have been
shown to correlate with inammation and necrosis [1].
ab
38 Diaphragm
447
Fig. 38.2 (a) B mode imaging of the diaphragm in cross
section at end-expiration. The relatively anechoic diaphragm lies between the highly echogenic pleural (red
arrow) and peritoneal (green arrow) membranes. (b)
Caveats
Tdi measured at FRC in healthy volunteers has
varied across studies but is usually slightly
greater in men as compared to women and right
as compared to left (see Table38.1) [2–4]. It is
also somewhat correlated with height and weight
[5], is physiologically increased in association
with physical training (e.g., weight-lifting) [5],
and is pathologically increased in those with
chronic asthma and Duchenne muscular dystrophy [6, 7]. T
pulmonary disease states (increased, decreased,
or unchanged). Isolated values of Tdi (unless
markedly abnormal, e.g., below the lower limit of
normal or fth percentile; Table38.1) need to be
interpreted with caution. Ultrasound measurement
of Tdi has been validated in autopsy studies [8]
and has high intra-observer and inter-observer
reproducibility (±0.2mm) [9].
varies in different chronic cardio-
di
During inspiration, the lung shadow (blue arrow) enters
the ultrasound eld. This indicates that the probe is positioned cephalad relative to the zone of apposition and
should be moved down 1–2 intercostal spaces
Interpretation andEvidence
Lower Tdi measured at the outset of mechanical
ventilation is strongly associated with prolonged
ventilation and increased mortality [10]. This association may reect the impact of diaphragm atrophy or it may suggest a more general lack of
physiological reserve. Both increases and decreases
in Tdi over time during mechanical ventilation are
associated with diaphragm dysfunction, prolonged
ventilation, and poor outcomes [11]. Decreases in
T
over time reect diaphragm atrophy as observed
di
in animal models of ventilator- induced diaphragm
function [12, 13]; the mechanism underlying pathological increases in Tdi is uncertain but may reect
load-induced injury. Increases in echodensity over
time during mechanical ventilation may represent
muscle necrosis and/or edema. Increased echodensity is associated with fewer ventilator-free days
and a trend toward increased mortality [1].
448
I. Morris and E. Goligher
Table 38.1
Normal values taken from studies in healthy non-ventilated volunteers
Diaphragm thickness at end FRC
Study Number Side Men Women
Boon etal. (2013)
[4]
Cardenas (2018)
[3]
150
Supine
64
Semi-
Mean±SD
(mm)
Right
Left
3.8±1.5
3.7±1.7
Right 1.9±0.3 1.3 1.8±0.3 1.2
LLN
(mm)
1.7
1.6
Mean±SD
(mm)
2.7±1.0
3.1±1.9
recumbent
Boussuges etal.
(2021) [2]
200
Seated
Right
Left
2.1±0.4
2.0±0.4
1.3
1.3
1.9±0.4
1.7±0.3
Diaphragm thickening fraction expressed as %
Study Number Breath type Mean (%) LLN (%)
Boon etal. (2013)
a
[4]
150 supine Inspiratory
capacity
Men (right)
Men (left)
Women
(right)
80
100
80
90
20
30
30
30
Women (left)
Harper etal. (2013)
a
[15]
Cardenas etal.
(2018) [3]
150 supine Quiet breathing
Right
Left
64
semirecumbent
Inspiratory
capacity
Men (right)
Women
20
23
204
170
18
20
80
82
(right)
Boussuges etal.
(2021) [2]
200 seated Inspiratory
capacity
Men (right)
Men (left)
Women
(right)
106
112
116
121
40
39
39
48
Women (left)
Diaphragm excursion
Study Number Breath type Men Women
Cardenas etal.
(2018) [3]
64
semirecumbent
Right
Quiet
breathing
Mean±SD
(cm)
1.52±0.43
7.79±0.82
LLN
(cm)
0.66
6.15
Mean±SD
(cm)
1.41±0.32
6.41±1.02
Deep
breathing
Boussuges etal.
(2021) [2]
200 seated Quiet breathing
Right
Left
2.0±0.5
2.2±0.6
n/a 1.9±0.5
1.9±0.5
Deep breathing
Right
Left
6.0±0.9
6.2±0.9
n/a 5.0±0.9
5.0±0.7
Voluntary sniff
Right
Left
FRC functional residual capacity, SD standard deviation, LLN lower limit of normal, n/a not applicable
a
Values of thickening ratio re-expressed as thickening fraction (%)
2.7±0.7
2.8±0.8
n/a 2.3±0.7
2.4±0.6
LLN
(mm)
1.5
1.4
1.1
1.1
LLN
(cm)
0.77
4.37
n/a
n/a
n/a
38 Diaphragm
449
Diaphragm Thickening
Measurement
As the diaphragm contracts, it shortens. The resulting overlap of myolaments causes the muscle to
thicken. This contractile thickening can be quantied by ultrasound using M mode. It is imperative
to keep the probe perpendicular to the muscle at
the zone of apposition to avoid biasing measurements by off-axis imaging. Maximal (peak inspiratory thickness, Tpi) and minimal (end expiratory
thickness, Tdi) thicknesses can be measured
(Fig.38.3) and expressed as either thickening ratio
(Tpi/Tdi) [2, 4, 14, 15] or thickening fraction (TFdi,
(Tpi−Tdi)/Tdi (×100 to express as percentage)) with
the latter being more commonly used in the critical
care literature. TFdi can be measured during tidal
breathing to assess resting diaphragm contractile
activity or during a maximal inspiratory maneuver
(FRC to total lung capacity) to quantify maximal
diaphragm thickening as a measure of diaphragm
function. Measurement of maximal TFdi requires a
vigorous inspiratory effort from a cooperative
patient. In non-cooperative spontaneously ventilated patients, a maximal inspiratory effort can be
obtained by transiently occluding the endotracheal
tube with a one-way valve which only permits
exhalation, for up to 20s (the Marini maneuver)
[16, 17]. Immediately following release of the
occlusion, maximal TFdi can be measured from the
stimulated respiratory efforts. The highest value of
3–5 maximal inspiratory efforts should be taken as
the maximal TFdi. During passive mechanical ventilation, breaths at <50% of maximal inspiratory
capacity and volumes <1.5 L (e.g., during tidal
breathing) have shown to not cause inadvertent
diaphragm thickening [9] and therefore, thickening that occurs during inspiration represents synergistic diaphragm contraction.
Callouts Pro–Tips
• Changes in diaphragm thickness during
mechanical ventilation are associated with
prolonged mechanical ventilation
• For a given level of muscular effort, the thickening and descent of the diaphragm as visualized by ultrasound is dependent on the
respiratory mechanics and clinical context
remains essential for interpretation
Caveats
The relationship between inspiratory thickening
of the diaphragm and muscular force generation
is complex. The presence of marked resistive or
elastic mechanical loads may reduce shortening
Fig. 38.3 (a) M mode
imaging of diaphragm
thickness and inspiratory
thickening during tidal
breathing.
Measurements of
thickness at end
expiration (T
inspiration (maximal
thickness) allow
calculation of thickening
fraction or thickening
ratio. (b) M mode
imaging of diaphragm
thickening during a sniff
inspiratory maneuver
) and
di
a
b
450
I. Morris and E. Goligher
and thickening of the diaphragm, even as it
generates very large transdiaphragmatic pressures. Additionally, when other ribcage inspiratory muscles are vigorously contracting, the
diaphragm dome may be “pulled” upward, reducing diaphragmatic shortening during contraction.
This reduces thickening of the muscle on ultrasound relative to force generation. Despite the
complexity of this mechanical system, diaphragm
thickening is a clinically useful measurement to
assess for the presence and magnitude of diaphragm contractile activation [11, 18, 19].
Measurement of TFdi has moderately good
repeatability (intra-user) and reproducibility
(inter-user) noting that TFdi incorporates measurement errors from both Tdi and Tpi [9].
Interpretation andEvidence
Maximal TFdi correlates with maximal inspiratory pressure [16] and a maximal TFdi value of
<20% is diagnostic for severe diaphragm weakness [11, 20]. Tidal TFdi has also been shown to
correlate with diaphragm strength and a value
below 25% measured in patients on a pressure
support mode of mechanical ventilation was
found to be as effective in predicting weaning
failure as diaphragm function assessed by twitch
tracheal pressure obtained by supramaximal
magnetic phrenic nerve stimulation [21]. During
the spontaneous breathing trial (whether on pressure support or T piece), a tidal TFdi of >30% predicts extubation success with greater
discrimination than clinical assessment by use of
the rapid shallow breathing index [22]. Finally, a
resting tidal TFdi between 15 and 30% has been
shown to be associated with the shortest duration
of mechanical ventilation [11] and targeting this
level of diaphragm activity during invasive ventilation may protect the diaphragm from both atrophy and load-induced injury [23].
Diaphragm Excursion
Measurement
The motion and descent (“excursion”) of the
dome of the diaphragm can be visualized using a
2–5MHz phased array ultrasound probe placed
below the subcostal margin at the midclavicular
line (Fig.38.4). The cursor of the probe must be
kept perpendicular to the dome to prevent mea-
Fig. 38.4 Diaphragm
excursion is measured
by quantifying the
maximal descent of the
dome of the diaphragm
on M mode (bottom
image). The dome of the
diaphragm can be best
identied on B mode
(upper image) and this is
used to conrm that the
ultrasound beam is
approximately
perpendicular to its peak
38 Diaphragm
451
surement error from foreshortening. Excursion
can be quantied in M mode during quiet breathing or during a maximal inspiratory effort. M
mode tracings can also be used to assess expiratory relaxation time, a measure of muscle fatigue.
Caveats
For a given contractile force, the distance that the
diaphragm dome descends will vary with changes
in end-expiratory lung volume and respiratory
mechanics (and as such may vary with posture
[24]). In patients receiving mechanical ventilatory
support, pressure and ow delivered by the ventilator inate the chest and contribute to diaphragm
excursion apart from any muscular contraction.
Consequently, this measurement can only be used
in ventilated patients to evaluate diaphragm function when ventilatory assistance is removed (i.e.,
continuous positive airway pressure, CPAP, or
T-piece). Paradoxical motion of the diaphragm
can sometimes be observed in patients with severe
diaphragm dysfunction, unilateral phrenic nerve
palsy, or in the presence of large pleural effusions
that invert the diaphragm [25–27].
sion also predicts an increased duration of
mechanical ventilation and hospitalization [30].
Diaphragmatic Strain andTissue
Doppler Imaging
Measurement
Diaphragmatic strain is measured by the speckle
tracking technique applied to cross-sectional
imaging of the diaphragm in the zone of apposition similar to the method for measuring Tdi [32].
Strain reects muscular deformation, theoretically a more direct assessment of contractile activation. Diaphragm motion has also been
quantied by tissue doppler imaging, an echocardiographic method of assessing high-amplitude
low-velocity signals of moving tissues. A
2–4MHz phased array probe is placed subcostally between the midclavicular and anterior axillary lines, perpendicular to the mid or posterior
1/3 of the hemidiaphragm. The velocities of contraction and relaxation can be computed from the
M-mode waveform, and this is correlated with
transdiaphragmatic pressure [33].
Interpretation andEvidence
Diaphragm excursion has excellent inter and
intra-observer reproducibility with limits of
agreement within approximately 10–15% of
mean measurements [28]. The normal range of
values for excursion has been published for a
variety of diaphragmatic maneuvers including
tidal breathing, snifng, and maximal inspiration
(Table38.1). Diaphragm excursion <2.5cm during a maximal inspiratory effort [29] and <1cm
during quiet breathing [30, 31] predicts diaphragm dysfunction. Reduced diaphragm excur-
Caveats
Measurement of strain by speckle tracking
requires specialized ultrasound equipment and
software not available on all bedside ultrasound
devices. Tissue doppler measurements are generally obtained for the right hemidiaphragm as the
contrast with the liver makes it easier to identify
and follow the motion of the diaphragm. Tissue
doppler measurements of diaphragmatic motion
are unable to distinguish passive and active force
generation during passive mechanical ventilation, and can only be used when inspiratory