Sensitivity of Lung Ultrasound for Postsurgical Pneumothorax

Lung Ultrasound Reduces Chest X-rays in Postoperative Care after Thoracic Surgery: Is There a Role for Artificial Intelligence?-Systematic Review

BACKGROUND

Chest X-ray (CXR) remains the standard imaging modality in postoperative care after non-cardiac thoracic surgery. Lung ultrasound (LUS) showed promising results in CXR reduction. The aim of this review was to identify areas where the evaluation of LUS videos by artificial intelligence could improve the implementation of LUS in thoracic surgery.

METHODS

A literature review of the replacement of the CXR by LUS after thoracic surgery and the evaluation of LUS videos by artificial intelligence after thoracic surgery was conducted in Medline.

RESULTS

Here, eight out of 10 reviewed studies evaluating LUS in CXR reduction showed that LUS can reduce CXR without a negative impact on patient outcome after thoracic surgery. No studies on the evaluation of LUS signs by artificial intelligence after thoracic surgery were found.

CONCLUSION

LUS can reduce CXR after thoracic surgery. We presume that artificial intelligence could help increase the LUS accuracy, objectify the LUS findings, shorten the learning curve, and decrease the number of inconclusive results. To confirm this assumption, clinical trials are necessary. This research is funded by the Slovak Research and Development Agency, grant number APVV 20-0232.

Sensitivity of chest ultrasound for postoperative pneumothorax in comparison to chest X-ray after lung resecting surgery

OBJECTIVES

Thoracic ultrasound is superior to chest X-ray for the detection of a pneumothorax in trauma and intensive care medicine. Data regarding its use in non-cardiac thoracic surgery are scarce and contradictory. Previous studies are heterogeneous regarding sonographic methodology and patient selection. This study aimed to evaluate the accuracy of thoracic ultrasound for pneumothorax assessment after lung resecting surgery in unselected patients.

METHODS

SONOR (SONOgraphy vs x-Ray) is a prospective observational trial (registry-ID DRKS00014557). A total of 123 consecutive patients with lung resecting surgery received a standardized thoracic ultrasound the same day and in addition to routine chest X-rays in erect position after removal of the chest tube. The sonographer was blinded to radiological findings and vice versa.

RESULTS

Sensitivity, specificity, positive and negative predictive values of ultrasound after removing the chest tube were 0.32, 0.85, 0.54, 0.69 for any pneumothorax and 1.0, 0.82, 0.19, 1.0 for pneumothorax ≥3 cm. No clinically relevant pneumothorax was missed. The agreement between sonography- and routine-based therapeutic decisions was 97%. Lung pulse was the most frequently detected sign to sonographically rule out a pneumothorax.

CONCLUSIONS

Postoperative thoracic ultrasound in unselected patients has a low overall sensitivity to detect a residual pneumothorax; however, its sensitivity and negative predictive values regarding clinically relevant pneumothorax are high. Test quality depends on the distinct sonographic methodology and patient selection. Anatomic differences in postsurgical and medical patients may be responsible for the contradictory results of previous trials. Studies with a larger population size are required to validate the accuracy of relevant pneumothoraces and identify appropriate selection criteria.

CLINICAL TRIAL REGISTRATION NUMBER

DRKS-German Clinical Trials Register, www.drks.de, registry-ID DRKS00014557.

Most patient conditions do not a priori debilitate the sensitivity of thoracic ultrasound in thoracic surgery-a prospective comparative study

Background

The few existing studies on the accuracy of lung ultrasound in the detection of a postoperative pneumothorax after thoracic surgery differ in the sonographic technique and the inclusion criteria. Several conditions are considered unfavourable in the sonographic examination of the lung. We aim to test these conditions for their impact on the diagnostic accuracy of lung ultrasound.

Methods

We compared lung ultrasound and chest roentgenograms for the detection of a pneumothorax after lung-resecting surgery in two prospective trials (register ID DRKS00014557 and DRKS00020216). The ultrasound examiners and radiologists were blinded towards the corresponding findings. We performed posthoc subgroup analyses to determine the influence of various patient or surgery related conditions on the sensitivity and specificity of ultrasound in the detection of pneumothorax.

Results

We performed 340 examinations in 208 patients. The covariates were age, gender, body mass index, smoking status, severity of chronic obstructive pulmonary disease, previous ipsilateral operation or irradiation, thoracotomy, postoperative skin emphysema, indwelling chest tube and X-ray in supine position. In univariate analysis, an indwelling chest-tube was associated with a higher sensitivity (58%, p = 0.04), and a postoperative subcutaneous emphysema with a lower specificity (73% vs. 88%, p = 0.02). None of the other subgroups differed in sensitivity or specificity from the total population .

Conclusions

Most of the patient- or surgery related conditions usually considered unfavourable for lung ultrasound did not impair the sensitivity or specificity of lung ultrasound. Further studies should not excluce patients with these conditions, but test the accuracy under routine conditions.

Trial registration

DRKS, DRKS00014557, registered 06/09/2018, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00014557 and DRKS00020216, registered 03/12/2019, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00020216

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01454-6.

Sensitivity of lung ultrasound for the detection of pneumothorax one day after pulmonary resection—a prospective observational study

Background

Chest X‑ray (CXR) after thoracic surgery contributes to patient discomfort and costs and is of limited therapeutic value. Lung ultrasound (LU) for pneumothorax may be an alternative to CXR, but diagnostic accuracy data are heterogeneous and biased by insufficient sonographic technique and patient selection. Reported sensitivities range from 0.21 to 1.0. We evaluated the sensitivity of LU on the first day after thoracic surgery under routine conditions.

Methods

We performed a prospective observational study (trial-ID DRKS00014557). Consecutive patients undergoing lung resection received standardized LU in addition to routine CXR on the first postoperative day. Ultrasound examiner and radiologist were blinded to corresponding X‑ray and ultrasound findings. CXR was used as reference to determine diagnostic test performance of ultrasound. The conformity of sonography- and routine-based therapeutic decisions was evaluated.

Results

A total of 68 patients were examined. The mean duration of ultrasound was 145 ± 64 s. CXR identified 23 patients with pneumothorax with a mean apex-to-cupola size of 1.5 ± 1.0 cm. Ultrasound detected 18 patients with pneumothorax. The computed sensitivity of LU was 0.48 (95% confidence interval [0.36; 0.60]). Specificity was between 0.81 and 1.0, the negative predictive value 0.76 [0.66; 0.86]. The sensitivity of CXR was 0.56 [0.44; 0.68]. Air leakage via chest tube correlated weakly with CXR (spearman’s rho = 0.26) and moderately with LU (rho = 0.43). The conformity between sonographically based recommendations and the actual therapy based on routine diagnostics was 96%.

Conclusions

Sensitivity of ultrasound for pneumothorax detection nearly reached CXR and resulted in equally safe patient management. Our data can serve as a pilot study for upcoming larger-scaled controlled trials.