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Three Part Question

In [critically ill patients presenting respiratory illness] is [ultrasound in addition to CXR] better at [increased diagnosis and improved patient outcome]?

Clinical Scenario

51 year-old man present to ICU with respiratory symptoms, increased oxygen requirement, SOB and increased WOB. He has a background of TIIDM. ABG revealed type one respiratory failure.

Patient not weaning. Clinical examination reveals bilateral dull percussion, reduced basal expansion. Portable CXR bibasal consolidation/atelectasis ?infection.
COVID -ve. Consultant perform lung ultrasound and revealed bilateral pleural effusion worse on right which was tapped.

You wonder if doing ultrasound on everyone would change clinical management and impact on patients quality of care if done routinely.

Search Strategy

The search strategy was continued from previous systematic review which was registered on the International Prospective Register of Systematic Reviews. An extension of the search strategy to March 2022 revealed 502 additional papers. Through an abstract sift, the results were reduced to 11. On review of the results, no papers met the three part question.

Embase (1947 - March 2022), Medline (1947 - March 2022) Cochrane database of systematic reviews (2015 - 2022) using the Ovid interface. Reference lists of relevant articles were also hand searched.

A scoping search was also undertaken using the Ovid database.

1 The impact of lung ultrasound on clinical-decision making across departments: a systematic review.m_titl. 1
2. "Chest".kw. 896
3. "Clinical-decision making".kw. 2006
4. "Lung".kw. 16132
5. "Management".kw. 17544
6. "Ultrasonography".kw. 24838
7. 2 or 4 16949
8. 3 or 5 19538
9. 6 and 7 and 8 3
10. 6 and 7 83
11. critical care.mp. or intensive care/ 169437
12. 10 and 11 12
13. respiratory illness.mp. or respiratory tract disease/ 69857
14. 6 and 11 and 13 5

Key
Mp. = free text term
Term/ = subject heading
Exp. Term/ = exploded subject heading i.e. subject heading along with all terms below in the tree
KW. = key word heading
A comprehensive search strategy. Inclusion criteria included changes in clinical decision making after using ultrasound.

Search Outcome

The recent systematic review by Heldeweg et al. 2022 on this topic was included. Updating this search strategy within the last year revealed one systematic review identified to the three part question. However, this article contained no information relevant to the ICU department. It was therefore removed form the analysis.

These are directly relevant papers to critical care practice listed below from a literature review:

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Heldeweg, M. et al. 2022 The Netherlands	504 patients within ICU (5 studies) systematic review investigating changes in clinical-decision making following lung ultrasound examination exclusively or as a part of thoracic ultrasound. Clinical-decision making was defined as either a clinician’s diagnosis, management, or therapy.	Systematic review	LUS changed the diagnosis in mean	44% (34-58%)	Clinican behaviour is not necessary associated with the improvement of patient-centred outcomes. More blinded studies or randomisation would avoid co-founding factors. Assesment of publication bias was not done.
			LUS changed the management in mean	42% (30-68%
			Therapy changes in management	51% non-invasive change sub-divided into (pharmacological, fluids, ventilator settings, physiotherapy)
			Risk of bias across studies	Moderate to high
Smit, J. et al. 2022 Netherlands	87 Adult patients admitted to the ICU who underwent thoracic ultrasound for any clinical indication were included. All lung ultrasound operators were blinded for any CT findings.	Single centre prospective observational accuracy study.	Diagnostic accuracy of LUS in detection	Adequate diagnostic modality in detection of consolidation, pleural effusion and significant pneumothorax	Single centre observational study. LUS was performed by clinicians with variable levels of experience. This lead to highly experienced operators more likely to detect subtle abnormalities thus better abltiy in classification of pathology.
			Diagnostic accuracy of 12-zone vs. 6-zone.	Extended lung scanning showed no improvement on diagnosis of lung pathology.
Winkler, M. et al. 2018 The Netherlands	543 patient admitted to the ICU. Meta-analysis included 10 full text studies.	Systematic review and Meta-analysis. Randomised controlled trials, cross-sectional case control and observational studies.	Evaluate the diagnostic accuracy of CXR compared with CT with respiratory symptoms	CXR has low sensitivity (49%) and good specificity (92%) in critical care.	There is need for a larger (multi centre) trials in comparing CXR and LUS accuracy compared to the gold standard. Most studies do not mention the ultrasound operators experience thus varying the potential form of bias.
			Evaluate the diagnostic accuracy of LUS compared with CT with pulmonary symptoms	LUS was superior to CXR as sensitivity (95%) was higher than CXR and specificity (94%) even higher.
Tierney, D. et al. 2020 USA	67 patients on ICU	Prospective cohort study	LUS examinations	One of four clinicians with three plus years experience + one hour pre study session on classification.	Inclusion requirement for CT and pCXR within 24 hours of PU examination may have introduced a bias for more severe illness in this subgroup. Although not detracting from the findings, this may impact generalisability.
			Evaluate accuracy of CXR with LUS	LUS had better agreement with CT than CXR across a variety of findings.
Brogi, E. et al. 2017 Italy	1869 adult patients in group A and 2265 adult patients in group B	Single centre observational retrospective cohort study.	Introducing LUS in daily routine	Lead to a reduction in CXRs without affecting outcome.	Unable to evaluate number of CXRs or LUS were normal and how many had pathology within the groups. The use of CXR or LUS was at the decision of the consultant.
			LUS lead to important changes in practice	Assesment of efficacy of ongoing interventions, with high diagnostic accuracy and specificity.
Danish, M. et al 2019 India	Ninety patients admitted to ICU	Cross-sectional observational study	6-point LUS to screen for respiratory pathology	LUS had better sensitivity and diagnostic accuracy than CXR	Patients studied had ALI >1, results may have differed if normal lung enrolled. No comment on experience of ultrasound operators skill.
			LUS accuracy in mechanically ventilated patients	LUS had better diagnostic accuracy in diagnosis.
Hew, M. et al. 2015 Australia	194 adult patients diagnosed with respiratory failure.	Systematic review - cohort study	Comparator CXR vs LUS with reference standard of CT thorax	Greater sensitivity in LUS than CXR in two studies.	Small body of evidence at high risk of selection bias
			LUS for diagnosis of CT detected consolidation	Sensitivity ranged from 0.91 (95% CI 0.81 to 0.97) to 1.00 (95% CI 0.95 to 1.00). Specificity ranged from 0.78 (95% CI 0.52 to 0.94) to 1.00 (0.99 to 1.00)

Comment(s)

In the management of the critically ill the use of thoracic imaging is frequently needed due to the constant changes in their clinical picture. Bedside sonography or Lung ultrasound (LUS) is being used in routine clinical assessment for many common applications within the critical care environment. LUS is a non-invasive diagnostic tool used to diagnose pathology in critically ill patients and has been suggested in being superior to CXR as a diagnostic tool in diagnosis in lung pathology in the critically ill, with studies showing that the use of chest radiography diagnosis accuracy is relatively low (Nazerian et al, 2015) and within critical care there are other technical issues leading to inaccurate diagnosis (Lichtenstein et al, 2004). This literature review focus on the use of LUS in the change management in clinical decision making within critical care unit. There is a growing body of literature recognising the use of LUS for evaluating lung pathology (Xirouchaki et al. 2011; Lichtenstein et al. 2004). Radiological imaging consists of chest x-ray (CXR) and computed tomography (CT) used a common diagnostic tools, however, recently there has been growing popularity in the of ultrasound. CT scan remains the gold standard in identification of thoracic pathology (Bouhemad et al. 2007), but transportation outside the ICU is challenging and potentially harmful (Dunn et al, 2007). There is potential that use of LUS may reduce the use of routine CXR and chest CT scans, without affecting patient outcome, thus reducing radiation exposure (Brogi et al, 2017). Gargani & Picano (2015) highlights the exposure of multiple radiological imaging has increased incidences of radiation-induced cancers. Point of care LUS has shown many advantages as its use as quick, non-invasive, portable and reliable assessment of the lung and condition without exposure to harmful radiation. With is ease to learn (Miller, 2016) and it’s portable use bedside allows for the differential diagnosis and diagnosis of therapeutic management of complex pathologies such as respiratory failure within the critical care environment (Lichtenstein & Meziere, 2008). The use of LUS findings can identify a range of pathology including: pleural effusions, consolidation, pneumothorax and empyema (Wimalasena et al. 2018; Mongodi et al, 2016). The use of LUS has been shown to be as specific and as sensitive in revealing lung consolidation which can be detected by CT scan in a systematic review by Hew et al. (2015). LUS has better accuracy in the diagnosis of pneumonic changes comparable to CXR (Amatya et al. 2018) and comparable to CT thorax in diagnostic accuracy (Xirouchaki et al. 2011). Search Strategy - Using a PICO P In Critically ill patients with respiratory illness does the use of lung ultrasound in addition to CXR compared to standard of care alone increase speed of diagnosis and improve patient outcome? I Lung / thoracic ultrasound C Comparator is standard care O Impact on clinical decision making (change in diagnosis, management or therapy) References

Clinical Bottom Line

Lung ultrasound has become popular in the treatment of the critically ill patient and has generated enthusiasm worldwide. The use of this tool can be used to assess and monitor lung tissue in patients with respiratory failure. It’s use in the ventilated population to guide procedures such as ventilation strategies, recruitment manoeuvres, pronation, bronchoscopy and drainage of plural fluid. There is significant heterogeneity across the studies, in the majority of the papers LUS is that is operator dependant, by non-image trained clinicians, but demonstrated high specificity and sensitivity in diagnosis. There are issues highlighted with the methodology and heterogeneity needed for larger study sizes. With adequate training and a sound understanding of images will allow for expertise of LUS. There needs to be a structured training programme for its use within critical care.

References

1. Heldeweg, M., Vermue, L., Kant, M., Brouwer, M. Girbes, A., Haaksma, M., Heunks, L., et al. The impact of lung ultrasound on clinical-decision making across departments: a systematic review. Springer
2. Smit, J., Haaksma, M., Winkler, M., Heldweg, M., Arts, L., et al. Lung Ultrasound in a tertiary intensive care unit population: a diagnostic study BMC 17th September 2021 25: 339
3. Winkler, M., Touw, H., van de Ven, P., Twisk, J. Tuinman, P. Diagnostic Accuracy of Chest Radiograph, and When Concomitantly Studied Lung Ultrasound, in Critically Ill Patients With Respiratory Symptoms: A Systematic Review and Meta-Analysis Critical Care Medicine July 2018; 707-714
4. Tierney, D., Huelster, J., Overgaard, J., Plunkett, M., Boland, L., St. Hill, C., Agboto, V., Smith, C., Mikel, B., Weise, B., Madigan, K., Doshi, A., Melamed, R. Comparative Performance of Pulmonary Ultrasound, Chest Radiograph, and CT Among Patients With Acute Respiratory Failure Critical Care Medicine February; 48(2): 151 - 157
5. Brogi, E., Bignami, E., Sidoti, A., Shawar, M., Gargani, L. Could the use of bedside lung ultrasound reduce the number of chest x-rays in the intensive care unit? Cardiovascular Ultrasound 13th September;
6. Danish, M., Agawal, A., Goyal, P., Gupta, D., et al. Diagnostic Performance of 6-Point Lung Ultrasound in ICU Patients: A Comparison with Chest X-Ray and CT Thorax Turk J Anaesthesiol Reanim August 2019; 47(4): 307 -319
7. Hew, M., Corcoran, J., Harriss, E. Rahman, N., Mallett, S. The diagnostic accuracy of chest ultrasound for CT-detected radiographic consolidation in hospitalised adults with acute respiratory failure: a systematic review BMJ Open September 2015; e007838