SonographicSonographic evaluation of the evaluation of the

diaphragm in critically ill patients.diaphragm in critically ill patients.

Technique and clinical applicationsTechnique and clinical applications

Intensive Care Med

Published online 24 January 2013

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Introduction Introduction

�Bedside ultrasonography a valuable

tool in the management of ICU patients

- noninvasive technique

- accurate, safe ,easy to use bedside

modality

�difficulty of patient transportation to the

radiology department due to illness severity

IntroductionIntroduction

�The diaphragm is the principal respiratory muscle

�Diaphragm dysfunction

- respiratory complications

- prolong the duration of mechanical ventilation

�Abnormal diaphragmatic motion

- phrenic nerve injury

- neuromuscular diseases

- after abdominal or cardiac surgery

- in critically ill patients under mechanical ventilation

Introduction Introduction

�observation of the diaphragm kineticsseems essential

�Previous

- fluoroscopy, CT

=> risks of ionizing radiation

- transdiaphragmatic pressure measurement, diaphragmatic electromyography, phrenic nerve stimulation, MRI

=> complex, highly specialized nature, requiring a skilled operator

InotroductionInotroduction

�Sonography receives increasing recognition as a fast, easy and accurate method of noninvasively evaluating diaphragmatic function at the bedside.

�Show in this review

SonographicSonographic technique of technique of

diaphragmatic evaluationdiaphragmatic evaluation

�3.5–5 MHz phased array probe

�Place

-> right or left costal margin

= mid-clavicular line

= anterior axillary line

-> directed medially, cephalad and dorsally

� the diaphragmatic excursion

(displacement,cm),

� the speed of diaphragmatic contraction

(slope,cm/s),

� the inspiratory time(Tinsp,s)

� the duration of the cycle(Ttot,s)

�The values of diaphragmatic excursion in healthy individuals

� the same diaphragmatic excursion values (1.8 cm) were found in ventilated patients who had succeeded in a weaning trial

� no difference between the right and the left hemidiaphragm in both studies

�The slope (speed) of diaphragmatic contraction,

- in forty healthy individuals

- quiet breathing

=> 1.3 ± 0.4 cm/s

�in M mode and 2D mode, a linear high-frequency probe (> 10 MHz) is necessary

�can be measured during quiet spontaneous breathing

�In normal individuals => ranging between 1.8 to 3 mm

�As lung volume increases from the residual volume (RV)to total lung capacity (TLC) there is a mean tdiincrease of 54 % (range 42–78 %)

Accuracy and reproducibilityAccuracy and reproducibility

�diaphragmatic excursion

�between 88 and 99 %

reproducibility right diaphragm Left diaphragm

Intraobserver 96% 91%

Interobserver 95% 91%

�Diaphragmatic thickness measurements

�Repeatability of intra-analyer and inter-analyser were all above 0.97

enhance reproducibilityenhance reproducibility

�little difference in the diaphragmatic

excursion between the middle and the

posterior part of the diaphragm

�measurements in M-mode

=> always be as strictly perpendicularas possible

�for diaphragmatic thickness

=>higher resolution linear probe (>10 MHz) is necessary

Limitations of the techniqueLimitations of the technique

� poor acoustic window(poor quality images) => between 2 and 10 %

� as perpendicular as possible to the diaphragmatic

excursion line

� pt is under assisted modes of mechanical

ventilation

- the sum of two forces

1. diaphragmatic contraction by itself

2. displacement of the diaphragm by the

pressure applied by the ventilator

patientpatient––ventilator interactionsventilator interactions

the second diaphragmatic contraction prolongs the

inspiratory time of the assisted breath

left, diaphragmatic contraction : 510 ms

right, contraction <---> triggering : 350 ms

SonographicSonographic evaluation of evaluation of

diaphragmatic weaknessdiaphragmatic weakness

and paralysisand paralysis

MeasurementMeasurement

� gold standard for diagnosing bilateral diaphragmatic paralysis

=>Measurement of transdiaphragmatic(Pdi) pressure

�poorly sensitive

�ineffective to diagnose unilateral diaphragmatic paralysis

MeasurementMeasurement

� Fluoroscopic examination

=> useful in patients with unilateral diaphragmatic paralysis

� false negative results frequently occur

� Pulmonary function tests

� highly dependent on lung volumes and patient effort

MeasurementMeasurement

� MRI

=> excursion, synchronicity and velocity of diaphragmatic motion

� not easily applicable in ICU patients

� intubated and mechanically ventilated.

SonographySonography

� Sonography

=> simple, noninvasive, ideal for repeated, prolonged examinations

=>uni- or bilateral diaphragmatic paralysis.

� Diagnosed diaphragm motion abnormalities in 22 patients

fluoroscopy => seven patient

SonographySonography

� distinguishing diaphragmatic weakness from paralysis

� diaphragmatic weakness

=> reduced diaphragmatic movement

� diaphragmatic paralysis

=>paradoxical motion

Diaphragmatic Diaphragmatic sonographysonography in in

ICU patients during partial ICU patients during partial

ventilatoryventilatory supportsupport

� Traditionally

->Measure esophageal and gastric pressure,

-> to evaluate inspiratory effort

� M-mode sonography

->provides a mirror image of the changes in esophageal pressure

� allow visualizing that each patient’s inspiratory effort triggers the ventilator appropriately

PostPost--operative diaphragmatic dysfunctionoperative diaphragmatic dysfunction

� Diaphragmatic dysfunction contributes to the etiology of postoperative pulmonary complications after thoracic and abdominal surgery

� leading to delayed weaning and prolonged stay in ICU

Weaning from mechanical Weaning from mechanical

ventilationventilation

� 55 patients

� Using a mean cutoff value of 1.1 cm of liver and spleen displacement to predict successful extubation

- sensitivity - 84.4 %

- specificity - 82.6 %

� Better than traditional weaning parameters

� 88 medical intensive care unit patients

� prevalence of ultrasonographicdiaphragmatic dysfunction of 29 %

- longer weaning times

- total ventilation times

� may be useful in identifying patients at high risk of difficult weaning

Future applications and Future applications and

conclusionsconclusions

� Ultrasonography appears to be a promising tool in the evaluation of diaphragmatic function in ICU patients

� fully noninvasive, widely available

� Provides qualitative and quantitative information

� Further research

� regarding ultrasonographicdiaphragmatic evaluation

� in pathologies such as sepsis, ventilator-induced diaphragmatic dysfunction and ICU neuromyopathy

� are anticipated with great interest.

� Thanks for your attention!!