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. 2023 May 6;15(1):23.
doi: 10.1186/s13089-023-00318-5.

Airway ultrasound to detect subglottic secretion above endotracheal tube cuff

Osman Adi  1 , Chan Pei Fong  2 , Roslanuddin Mohd Sallehuddin  3 , Azma Haryaty Ahmad  2 , Kok Meng Sum  4 , Zulrushdi Md Yusof  5 , Gabriele Via  6 , Guido Tavazzi  7   8
Affiliations

Airway ultrasound to detect subglottic secretion above endotracheal tube cuff

Osman Adi et al. Ultrasound J. .

Abstract

Background: Subglottic secretion had been proven as one of the causes of microaspiration and increased risk of ventilator-associated pneumonia (VAP). The role of ultrasound to detect subglottic secretion has not yet been established.

Purpose: The purpose of this study is to determine the sensitivity and specificity of upper airway ultrasound (US) in the detection of subglottic secretions as compared to computed tomography (CT) scanning.

Material and methods: A prospective observational study was carried out in adult trauma patients requiring mechanical ventilation and cervical CT scan. All patients had an endotracheal tube cuff-pressure maintained between 20 and 30 cm H2O. Airway US was performed at the bedside immediately before the patient was transferred to the CT scan suite. The sensitivity, specificity, and positive/negative predictive values (PPV, NPV) of the upper airway US detection of subglottic secretions were then calculated and compared with CT findings.

Results: Fifty participants were consecutively included. Subglottic secretions were detected in 31 patients using upper airway US. The sensitivity and specificity of upper airway US in detecting subglottic secretion were 96.7% and 90%, respectively (PPV 93.5%, NPV 94.7%). 18 (58%) patients with subglottic secretions developed VAP during their ICU stay (p = 0.01). The area under the receiver operating curve (AUROC) was 0.977 (95% CI 0.936-1.00).

Conclusions: Upper airway US is a useful tool for detecting subglottic secretions with high sensitivity and specificity.

Clinical implications: This study shows: 1. Upper airway US may aid in detecting subglottic secretions, which are linked to VAP. 2. Detecting subglottic secretions at the bedside aids in determining the best frequency of subglottic aspiration to clean the subglottic trachea. 3. Upper airway US may also aid in detecting the correct ETT position. Trial registration Clinicaltrials.gov.

Clinicaltrials: gov identifier NCT04739878 Date of registration 2nd May 2021 URL of trial registry record https://clinicaltrials.gov/ct2/show/NCT04739878 .

Keywords: Focused airway ultrasound; Microaspiration; Point-of-care ultrasound; Subglottic secretion; Ventilator-associated pneumonia prevention.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
a A longitudinal view was obtained with the transducer placed at the anterior midline of the neck; b airway ultrasound (longitudinal view) showing subglottic secretions. c Relation of heterogenous subglottic secretions (blue watermark) and homogenous subglottic secretions (green watermark) with endotracheal (ETT) cuff, cricoid cartilage (CC) and cricothyroid membrane (yellow line)
Fig. 2
Fig. 2
a A transverse view was obtained with the transducer placed across the anterior surface of the neck at the level of cricoid cartilage. b A cross-section of the cricoid cartilage (yellow watermark), ETT (white line) and presence of subglottic secretions (green watermark) were depicted
Fig. 3
Fig. 3
a and b A sagittal view of cervical CT scan showed a subglottic secretions (green watermark) above the ETT cuff (pink watermark) and its relation with other structures; c and d axial views of cervical CT showed subglottic secretions. Ss subglottic secretion; C cricoid cartilage; T thyroid cartilage; ETT endotracheal tube
Fig. 4
Fig. 4
STARD flow diagram
Fig. 5
Fig. 5
Area under receiver operating curve (AUROC) US Subglottic Secretion Score vs gold standard (CT cervical detection of subglottic secretion) AUROC = 0.977, p < 0.001
See this image and copyright information in PMC

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