Substituting Lung Ultrasound for Chest Xray in Pediatric Pneumonia

PedPNAByte


Feasibility and Safety of Substituting Lung Ultrasound for Chest Radiography When Diagnosing Pneumonia in Children: A Randomized Controlled Trial

CHEST July 2016 - Pubmed Link


Background

Pneumonia is a leading cause of death in children worldwide. Physical exam and symptoms are not reliable for diagnosis, and chest xray is not available in all parts of the world. Lung ultrasound is known to be accurate for pneumonia and has more portability, less radiation, and less cost.


Questions

Is substituting a lung ultrasound for a chest xray in suspected pneumonia feasible and safe?

Can lung ultrasound reduce chest xrays needed?


Population

Urban pediatric emergency department

Convenience sample enrolled 24 hours a day, 7 days a week

Inclusion:

-age: birth to 21 yo

-suspicion of pneumonia requiring CXR for evaluation (fever, cough, tachycardia, abnormal findings on auscultation)

Exclusion:

-previously performed CXR

-hemodynamically unstable


Who did the ultrasounds?

15 pediatric emergency medicine attendings and fellows, varying levels of experience

Training consisted of 1 hour lung ultrasound training session prior to start of study

-30 minutes lecture on recognizing pathology and pitfalls

-30 minutes hands on scanning on normal models


Design

Randomized to intervention and control in blocks of variable lengths. Intention to treat analysis.

Not blinded


Primary Outcome: difference in frequency of chest xray between the two groups

Stratified by level of experience: novice ≤25 LUS, experienced >25 LUS

Delineated sub-centimeter consolidations = < 1 cm and not seen on Chest xray


Secondary Outcomes Measured:

-Unscheduled heathcare visits 1-2 weeks after ED visit

-Antibiotic use

-ED length of stay (LOS)

-Hospital admission rates


Missed pneumonia defined as diagnosed by healthcare provider on repeat ED or healthcare visit (clinical or radiographic evidence) AND with the initiation of antibiotics

Power analysis: powered to detect 15% or more absolute reduction in CXR use


Intervention

Those randomized to intervention received:

1) Lung ultrasound

2) CXR only in the following circumstances:

a) discretion of the enrolling clinician

b) clinical uncertainty of findings

c) request of referring or admitting physician

d) request of patient guardian.


Control: CXR first, then all received lung ultrasound


Treatment decisions left to treating clinician's discretion

2 View CXRs interpreted by radiologists blinded to results


Scan

Linear high frequency transducer

6 zone scanning protocol (3 per side), perpendicular planes at each spot

  1. Midclavicular Anterior

  2. Midclavicular Posterior

  3. Midaxillary - from axilla to diaphragm


Positive findings = lung consolidation with air bronchograms Airbronchogram


Negative findings = B-lines, subpleural consolidations without air bronchograms (considered likely viral etiology)


Lung Ultrasound Video Referenced in Study

Another Lung Ultrasound Example Referenced in Study

Another instructional Lung Ultrasound Video Referenced


More great links to help you understand lung ultrasound

5 Minute Sono - Air bronchograms

5 Minute Sono - Pneumonia


Results

191 enrolled and randomized, groups similar

Pneumonia in 14/103 (13.6%) investigational arm, 12/88 (13.6%) in control


Primary Findings

Reduction in cxr by 38.8% in intervention group

Number needed to scan (NNS) = 2.5 to save 1 child an xray


If xray had not been requested by others (n =29), there would have been a total of 67% reduction in cxr. (NNS = 1.5)

Stratified by experience:

Novice → 30% reduction in cxr

Experienced → 60.6% reduction in cxr

Stratified by age:

Less than or equal to 2 yo → 47.9% reduction

Greater than 2 yo → 30.9% reduction


Other Findings

No difference in missed pneumonia: Investigation group: 0%, Control 0%

No difference between groups for unscheduled heathcare visits, antibiotics use, radiographic pneumonia, ED length of stay, or hospital admission

However, in the LUS group that did not have chest xrays ordered (n= 40) there was reduction in LOS by 48 minutes


Mean lung ultrasound examination 7 minutes

Cost calculation - reduction in cxr saved approximately $9,200

Kappa between sonologist and expert doing quality assurance was 0.81


Limitations

Single center trial, Pediatric ED

Convenience sample

Not blinded to CXR when performing ultrasound

Excluded unstable patients

Could not calculate accuracy because no gold standard used between both groups (not everyone had cxr)

Unclear how many pneumonias were missed on ultrasound but caught on cxr when sonologist thought cxr was necessary. In the ultrasound first arm, there was 63/103 that got cxr. 29 of those 63 were ordered at the request of admitting physician, referring physician, or guardian. Therefore, there were 34/103 (33%) cases in which xray was ordered by the sonologist in the ultrasound first arm, but we don't know the specific reasons why.


Take Home Points

1. A lung ultrasound first approach in suspected pediatric pneumonia resulted in reduction in chest xray by 38.8%.

2. No pneumonias were missed in the lung ultrasound first arm (which included the use of chest xray when results unclear).


Our score

5 Probes


Cite this article as

Michael Prats, MD. Substituting Lung Ultrasound for Chest Xray in Pediatric Pneumonia. Ultrasound G.E.L. Podcast Blog. Published on October 10, 2016. Accessed on June 17, 2019. Available at http://www.ultrasoundgel.org/4.
Published on 10/10/16 04:00 AM
comments (0)