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Table 3 Diaphragm ultrasonography: transducer settings and technique

From: EXpert consensus On Diaphragm UltraSonography in the critically ill (EXODUS): a Delphi consensus statement on the measurement of diaphragm ultrasound-derived parameters in a critical care setting

Transducer settings

 

Excursion

 The ideal range is between 2 and 5 MHz (cardiac or abdominal transducer)

 The ideal mode is the M-mode

 Maximum depth should be adjusted to capture maximum excursion

 Gain should be adjusted to create ideal contrast with surrounding structures

Thickness

 The ideal range is between 7 and12 MHz (linear transducer)

 No consensus was achieved for preferring B-mode or M-mode

 Depth should be set just below to several centimetres under the diaphragm

 Gain should be adjusted to create ideal contrast with surrounding structures

 

Technique

 

Excursion

 The transducer should be aimed at the dome of the diaphragm

 No consensus was achieved on transducer placement on the abdomen

 Measurements are best performed in M-mode and during quiet breathing

 Organ displacement is a valid alternative for excursion if the diaphragm dome is hard to visualize

Thickness

 The transducer should be placed on the midaxillary line or slightly more ventral, approximately between the 8th and 11th rib, with lung slightly or just not moving into the image

 The transducer should be placed perpendicular to chest wall, so that all three layers (pleura, peritoneum and fibrous layer) are visible

 No consensus was achieved on transducer orientation to be in line with or perpendicular to the intercostal space

 Caliper placement should be as close as possible to the pleural and peritoneal line without including these lines in the measurement

 No consensus was achieved on the optimal breathing pattern for making measurements

Both

 Unilateral measurement of the diaphragm on the right side of the patient is an acceptable proxy for the whole diaphragm, unless there is any suspicion of unilateral pathology (e.g. thoracic surgery, phrenic nerve or spinal cord injury) in which case this needs to be excluded or measurements need to be taken on both sides