ultrasound outperforms the fifth intercostal space landmark for tube thoracostomy

site selection

Nitin Kuppanda, MD
Published March. 08, 2022

Probetrotters | Medical Education

Study Design

This is a single-site cross sectional study done at a single large academic emergency department using a non-randomized, convenience sample of patients.

Objective

The objective of the study was to assess whether ultrasound could help determine safety of chest tube insertion sites compared to the more commonly used blind, landmark approach at the fifth intercostal space along the midaxillary line.

Methods

Fifty participants at a large, academic tertiary care emergency department were identified as possible participants. Exclusion criteria were patients who were pregnant, prisoners, less than 18 years old or greater than 99 years old, refused to consent, or lacked capacity to consent. The participants of this study were placed in a supine position and the left and right fifth intercostal spaces were identified on a physical exam. Then, the curvilinear probe on the ultrasound machine was used to identify the diaphragms on each side. The study leaders (who were the sonographers) noted if the diaphragm was above, below, or crossed the fifth intercostal space during the respiratory cycle. This resulted in a total of 100 hemithoraces for evaluation as data points. Participant demographics were recorded for each patient: age, height, weight, gender, if there was a history of COPD, asthma, prior thoracostomy and prior thoracic surgery.  Statistical analysis was performed on the data points to determine the significance of the results.

What are some possible flaws in the methods used?

  • This was a convenience sample with a  small sample size: only 50 participants and only 100 hemithoraces.
  • Results of the study could be confounded by patients with respiratory diseases, such as COPD, or prior thoracic surgeries that change the lung anatomy. The study population did not necessarily have lung pathology such as pneumothorax or pleural effusions that would typically necessitate chest tube placement if indicated.
  • The study leaders did not ensure sample size representative of the US population (i.e. 50% of each gender).
  • There was no method to ensure that the 5th intercostal space was correctly identified. Another examiner did not confirm the position.

Results

81% of diaphragms were consistently below the 5th intercostal space, while 19% of diaphragms were either consistently above or had crossed the 5th intercostal space during respiration. The study showed diaphragms were above or crossing the 5th intercostal space during the respiratory cycle in 20% on the right side and 18% on the left side; in total, ultrasound had detected inaccurate locations 24% of the time, which is a significant incidence. Thus, ultrasound identified a safer thoracostomy tube placement site compared to the blind landmark approach, which can allow for more accurate localization and reduction in potential complications such as diaphragmatic injury and intra-abdominal penetration. These findings were statistically significant.

Discussion

Ultrasound has the potential to identify safer thoracostomy tube placement and thus reduce possible complications, such as diaphragmatic or subdiaphragmatic insertion. Most emergency physicians are well trained in the E-FAST exam and thus, can easily and quickly identify the diaphragm prior to chest tube insertion. This study shows that ultrasound could decrease morbidity, mortality, iatrogenic injuries, and medical expenses with the use of ultrasound prior to thoracostomy tube placement.

Limitations

  1. The sample size was small and not necessarily representative of the US population.
  2. Patients did not have pathology that would require chest tube insertion, such as pneumothorax or hemothorax, which may possibly alter location of the diaphragm.
  3. The diaphragm could be obscured by air during pneumothorax, thus making it difficult to identify the diaphragm with ultrasound, in which case ultrasound would not be able to identify a safe chest tube insertion site. This limitation of the ultrasound was not examined as none of the study participants had pneumothoraces.   
  4. The study did not adjust for patients with lung disease processes, such as COPD, or lung surgery that could possibly change location of the diaphragm.
  5. The study did not say where the diaphragm was located for the 19% of participants whose diaphragms either crossed or were consistently above the 5th intercostal space. Do practitioners need to insert the chest tube at the 4th intercostal space or a higher rib space for all patients? 

Take Home Points

 

    •  
       
      • The blind landmark approach of identifying the 5th intercostal space along the midaxillary line for chest tube insertion does not consistently  locate a point above the diaphragm, which could lead to complications.
      • Ultrasound can reduce the complications from chest tube insertion, such as diaphragmatic or sub-diaphragmatic insertion.

Does this study influence your practice?

Yes. This is a simple and easy way to identify chest tube insertion sites and could possibly reduce complications. In patients with blunt abdominal trauma, who may need chest tube insertions, physicians have to perform the E-FAST exam prior to starting the procedure, where the diaphragm is also identified. The site of the diaphragm could be marked, and the chest tube placed above that. I have seen a patient that had a subdiaphragmatic chest tube insertion and the use of ultrasound could have prevented that complication.

[1] Gray EJ, Cranford JA, Betcher JA, et al. Sonogram of safety: Ultrasound outperforms the fifth intercostal space landmark for tube thoracostomy site selection. Journal of Clinical Ultrasound. 2020;48(6):303-306. doi:10.1002/jcu.22851. https://onlinelibrary.wiley.com/doi/10.1002/jcu.22851

 

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