The diaphragm is a musculotendinous sheet. It is located at the inferior-most aspect of the ribcage and acts as the floor of the thoracic cavity and the roof of the abdominal cavity.

It has three muscular parts: sternal, costal, and lumbar. It is subdivided into two hemidiaphragms, each one innervated by the ipsilateral phrenic nerve (C3-C5 roots).

The left hemidiaphragm lies above the stomach and spleen. The liver is under the right hemidiaphragm. The heart is located above the diaphragm and fixed to it with its pericardial sheet. Lungs are also positioned above the diaphragm and have broad concave bases (facies diaphragmatica). They are surrounded by pulmonary pleurae, which consists of two layers: visceral and parietal.

The costodiaphragmatic recess (also known as the costophrenic recess or phrenicocostal sinus) is a space in the pleural cavity that is located at the lower border of the chest wall at the junction of the costal and diaphragmatic pleura. There are two lung wings in the human body. Consequently, we can find the left and right recess. Each recess extends from the 7th costal cartilage anteriorly to the neck of the 12th rib posteriorly. Its course is obliquely downward and backward. The recess is deepest after forced expiration and shallowest after forced inspiration. Pleural effusion collects in the recess when the person is standing. The curtain sign is useful in detecting early pulmonary pathological processes that occur at the costodiaphragmatic recesses and the lateral lung bases. The sign occurs when the aerated lung moves over an effusion with respiration.

The diaphragm has three openings called hiatuses. The following structures pass through them:

  • caval hiatus (Foramen v. cavae): inferior vena cava, terminal branches of phrenic nerves
  • esophageal hiatus (Hiatus oesophageus): esophagus, left and right vagus nerve, esophageal branches of left gastric artery/vein
  • aortic hiatus (Hiatus aorticus): aorta, thoracic duct, azygos vein
Costodiaphragmatic recess.

Gilroy, A. M. (2016). Atlas of Anatomy. New York: THIEME MEDICAL Publishers INC.

Diaphragmatic orginin and insertion

Available at: https://www.definitionfitness.com/blog/true-core-training/diaphragm-origin-insertion (Accessed: 13 november 2019).

Diaphragmatic left and right crus

Available at: https://www.definitionfitness.com/blog/true-core-training/diaphragm-origin-insertion (Accessed: 13 november 2019).

Diaphragm and the thoracic cavity

Gilroy, A. M. (2016). Atlas of Anatomy. New York: THIEME MEDICAL Publishers INC.

The diaphragm is the main respiratory muscle involved during inspiration. The contraction of the diaphragm leaflets lowers the diaphragm into the inspiratory position, increasing the volume of the pleural cavity. During passive expiration, the muscles of the rib cage relax, and the diaphragm returns to its expiratory position.

The role of diaphragm in respiration

Available at: https://anatomy-medicine.com (Accessed: 13 November 2019).

Ultrasound examination

Typically, the examination is done during spontaneous respiration, preferably in the supine position (less overall variability, less side-to-side variability, greater reproducibility). The examination can also be carried out in quiet respiration, during deep breathing or sniff maneuver.

The diaphragm is seen as a hyperechoic homogenous curved line between the lung and abdomen on the ultrasound. The right diaphragm is analyzed through the liver window and the left diaphragm through the spleen window. It is easier to assess the right hemidiaphragm rather than the left hemidiaphragm because of the limitations of the left spleen window and interference from the stomach.

There are many techniques/views to find the diaphragm: intercostal, anterior subcostal, posterior subcostal, and subxiphoid view.

Intercostal view

  • transducer: high frequency, linear (7-18 MHz)
  • position: in the anterior axillary line between the 7th and 8th  rib or the 8th and 9th rib
  • orientation: sagittal

The ideal image includes the two ribs with intercostal space between them.

Anterior subcostal view

  • transducer: low frequency, curvilinear (2-6 MHz)
  • position: between the midclavicular and anterior axillary line in the anterior subcostal region
  • orientation: medial, cranial and dorsal

Posterior subcostal view

  • transducer: low frequency, curvilinear (2-6 MHz)
  • position: posterior subcostal region in the sagittal planes
  • orientation: sagittal

Not commonly used technique (requires the patient to be seated).

Subxiphoid view

  • transducer: low frequency, curvilinear (2-6 MHz)
  • position: below the xiphoid
  • orientation: transverse, angled upwards

Useful in children.

Anterior subcostal view

Sarwal, A., Walker, F. O., & Cartwright, M. S. (2013). Neuromuscular ultrasound for evaluation of the diaphragm. Muscle & Nerve, 47(3), pp. 319–329. doi: 10.1002/mus.23671.

Posterior subcostal view

Sarwal, A., Walker, F. O., & Cartwright, M. S. (2013). Neuromuscular ultrasound for evaluation of the diaphragm. Muscle & Nerve, 47(3), pp. 319–329. doi: 10.1002/mus.23671.

Subxiphoid view

Sarwal, A., Walker, F. O., & Cartwright, M. S. (2013). Neuromuscular ultrasound for evaluation of the diaphragm. Muscle & Nerve, 47(3), pp. 319–329. doi: 10.1002/mus.23671.

THE LIVER WINDOW – RIGHT LUNG BASE

Right diaphragm and liver window

Available at: http://pie.med.utoronto.ca/POCUS/POCUS_content/lungUS.html (Accessed: 13 November 2019).

Diaphragm, parietal pleura and visceral pleura on liver window

Available at: http://pie.med.utoronto.ca/POCUS/POCUS_content/lungUS.html (Accessed: 13 November 2019).

Right pleural space and subphrenic space

Available at: https://www.salussonography.com/article/fast/fast_focused_assessment_with_sonography_in_trauma/32 (Accessed: 13 November 2019).

THE SPLEEN WINDOW – LEFT LUNG BASE

Left diaphragm and spleen window

Available at: http://pie.med.utoronto.ca/POCUS/POCUS_content/lungUS.html (Accessed: 13 November 2019).

Diaphragm, parietal pleura and visceral pleura on spleen window

Available at: http://pie.med.utoronto.ca/POCUS/POCUS_content/lungUS.html (Accessed: 13 November 2019).

Hepatorenal recess

Available at: https://www.salussonography.com/article/fast/fast_focused_assessment_with_sonography_in_trauma/32 (Accessed: 13 November 2019).

The vertebral column is not visualized above the diaphragm because of the presence of air, causing near-complete reflection of the ultrasound beam. This is referred to as a negative spine sign. In addition, the curtain sign should be observed. At full inspiration, the descent of the lung and diaphragm obscures the liver/spleen previously seen to the right of the image, and with expiration, these organs reappear in the ventral part of the diaphragm.

A. Positive curtain sign; B. Negative spine sign

Goffi, A., Kruisselbrink, R., & Volpicelli, G. (2018). The sound of air: point-of-care lung ultrasound in perioperative medicine. Canadian Journal of Anesthesia/Journal Canadien Danesthésie, 65(4), pp. 399–416.

Diaphragmatic rupture

The diaphragmatic rupture is a severe condition that requires surgical repair. It is an uncommon injury with a prevalence of 0.8%–1.6% of patients admitted with blunt injury. The left side is more frequently injured because the liver presumably plays a role in having a protective effect on the right side. It is also possible that a right-sided injury is underdiagnosed, and the diagnosis is often delayed because clinical and radiographic evaluations are insensitive.

The diagnosis of traumatic diaphragmatic rupture remains a challenge, and it can easily remain undetected at first examination.  It can remain undetected days or even years due to small rupture without severe symptoms. With time, the traumatic hernia canal widens, and larger parts of the abdominal organs are displaced into the chest, causing respiratory insufficiency or perfusion disturbances at the herniated organs. Clinical diagnosis is hardly reliable because clinical signs are not specific for diaphragmatic injury. There can be a complete lack of symptoms. Mild symptoms like nausea, difficulty in breathing, abdominal / thoracic / shoulder tip pain, or acute symptoms due to visceral obstruction, strangulation, or perforation, culminating in multiorgan failure can also present. When herniation of abdominal contents occurs, bowel sounds may be auscultated in the chest. A missed diaphragmatic injury may result in delayed herniation and strangulation of abdominal organs into the thoracic cavity through the unrepaired defect in the diaphragm.

Initial plain radiographs have demonstrated the sensitivities of 28–65%, and computed tomography has been shown to be 50–84% sensitive. Ultrasound is frequently utilized in the early evaluation of trauma patients to assess for fluid in the abdomen, pericardium, and chest.

Ultrasound examination:

There is no consensus on the sensitivity of ultrasound in this diagnosis, but some findings suggestive of diaphragmatic rupture can be seen on the ultrasound.

Findings include the use of M mode to demonstrate an abnormal diaphragmatic excursion, and the direct visualization of loops of bowel with peristalsis above the level of the diaphragm. E-FAST scan could be a useful diagnostic tool in determining the presence of haemothorax by looking above the diaphragms. It is simple to include a brief evaluation of diaphragm’s continuity, herniated abdominal content, or any sonographic signs suggestive of diaphragmatic rupture.

Other features of diaphragmatic rupture are:

  • floating and non-visualized diaphragm and subphrenic fluid collection,
  • right-sided diaphragmatic rupture – “liver sliding sign (hepatic parenchymal movement is seen against the parietal pleural surface where lung parenchyma is typically expected),
  • non-visualization of the spleen and heart -“Rip’s absent organ sign” describes another indirect marker for the diagnosis of diaphragmatic rupture,
  • presence of air in the stomach and splenic flexure of the colon.
Two rounded structures which could be either herniated stomach or loops of bowels

Tjhia, J., & Noor, J. M. (2017). Beyond E-FAST scan in trauma: Diagnosing of traumatic diaphragmatic rupture with bedside ultrasound. Hong Kong Journal of Emergency Medicine, 25(3), 163–165.

Disrupted diaphragm with loop structures

Tjhia, J., & Noor, J. M. (2017). Beyond E-FAST scan in trauma: Diagnosing of traumatic diaphragmatic rupture with bedside ultrasound. Hong Kong Journal of Emergency Medicine, 25(3), 163–165.

Diaphragm rupture showing pleural effusion and perisplenic fluid collection

Mathis, G. (2017). Chest sonography. Cham: Springer International Publishing Switzerland.

Resources

Kenhub. Diaphragm. Available at: https://www.kenhub.com/en/library/anatomy/diaphragm (Accessed: 13 November 2019).

Fayssoil, A. et al. (2018) ‘Diaphragm: Pathophysiology and Ultrasound Imaging in Neuromuscular Disorders’, Journal of Neuromuscular Diseases. IOS Press, pp. 1–10. doi: 10.3233/JND-170276.

Hofmann, Sabine & Kornmann, Marko & Henne-Bruns, Doris & Formentini, Andrea. (2012). Traumatic diaphragmatic ruptures: clinical presentation, diagnosis and surgical approach in adults. GMS Interdisciplinary Plastic and Reconstructive Surgery DGPW. 1. 10.3205/iprs000002.

Bothwell, J. et al. (2011) ‘Ultrasound diagnosis of diaphragmatic rupture’, Critical Ultrasound Journal. SpringerOpen, pp. 153–154. doi: 10.1007/s13089-011-0079-y.

Tjhia, J. and Noor, J. M. (2018) ‘Beyond E-FAST scan in trauma: Diagnosing of traumatic diaphragmatic rupture with bedside ultrasound’, Hong Kong Journal of Emergency Medicine. SAGE Publications, 25(3), pp. 163–165. doi: 10.1177/1024907917745234.

Goffi, A., Kruisselbrink, R. and Volpicelli, G. (2018) ‘The sound of air: point-of-care lung ultrasound in perioperative medicine’, Canadian Journal of Anesthesia. Springer New York LLC, pp. 399–416. doi: 10.1007/s12630-018-1062-x.

Tsui, J. J. and Tsui, B. C. H. (2016) ‘A novel systematic ABC approach to Diaphragmatic Evaluation (ABCDE)’, Canadian Journal of Anesthesia. Springer New York LLC, pp. 636–637. doi: 10.1007/s12630-015-0566-x.

Gilroy, A. M. (2016). Atlas of Anatomy. New York: THIEME MEDICAL Publishers INC. Human anatomy: Structure of the human body. Available at: https://anatomy-medicine.com/ (Accessed: 13 November 2019).

Lung Ultrasound. Available at: http://pie.med.utoronto.ca/POCUS/POCUS_content/lungUS.html (Accessed: 13 November 2019).