34 AJTCCM VOL. 31 NO. 1 2025
ORIGINAL ARTICLES: RESEARCH
Background. Pulmonary ultrasound techniques have historically been applied to acute lung diseases to describe lung lesions, particularly
in critical care.
Objectives. To explore the role of lung ultrasound (LUS) in hospitalised patients with hypoxaemic pneumonia during the COVID‑19 pandemic.
Methods. is was a single‑centre prospective, observational study of two groups of adult patients with hypoxaemic pneumonia: those with
COVID‑19 pneumonia, and those with non‑COVID‑19 community‑acquired pneumonia (CAP). A pulmonologist performed bedside LUS
using the Bedside Lung Ultrasound in Emergency (BLUE) protocol, and the ndings were veried by an independent study‑blinded radiologist.
Results. We enrolled 48 patients with COVID‑19 pneumonia and 24 with non‑COVID CAP. e COVID‑19 patients were signicantly older
than those with non‑COVID CAP (median (interquartile range (IQR)) age 52 (42‑62.5) years v. 42.5 (36‑52.5) years, respectively; p=0.007),
and had a lower prevalence of HIV infection (25% v. 54%, respectively; p=0.01) and higher prevalences of hypertension (54%v. 7%; p=0.002)
and diabetes mellitus (19% v. 8%; p=0.04). In both groups, close to 30% of the patients had severe acute respiratory distress syndrome.
Aconuent B‑line pattern in the right upper lobe was signicantly associated with COVID‑19 pneumonia compared with the C pattern
(relative risk (RR) 3.8; 95% condence interval (CI) 1.7‑8.6). Bilateral changes on LUS rather than unilateral or no changes were associated
with COVID‑19 pneumonia (RR 1.55; 95% CI1.004‑2.387). ere were no statistically signicant dierences in median (IQR) lung scores
between patients with COVID‑19 pneumonia and those with non‑COVID CAP (8 (4‑11.5) v. 7.5 (4.5‑12.5), respectively). Patients with
COVID‑19 pneumonia had a higher than predicted mortality. Logistic regression analysis showed a higher Simplied Acute Physiology
Score (SAPS II) (RR 1.11; 95% CI1.02‑1.21) and a lower total LUS score indicating B lines v. consolidation (RR 0.80; 95% CI0.65‑0.99)
to be associated with mortality.
Conclusion. Patients with right upper zone consolidation were more likely to have non‑COVID CAP than COVID‑19 pneumonia.
Findinga B pattern as opposed to consolidation was associated with mortality. e admission LUS score was unable to discriminate between
COVID‑19 and non‑COVID CAP, and did not correlate with the ratio of partial pressure of oxygen to fractional inspired oxygen, clinical
severity or mortality.
Keywords. COVID‑19, lung ultrasound, pneumonia.
Afr J Thoracic Crit Care Med 2025;31(1):e1887.https://doi.org/10.7196/AJTCCM.2025.v31i1.1887
Pulmonary ultrasound in COVID‑19 and non‑COVID‑19
pneumonia in South Africa: An observational study
S A van Blydenstein,1 MB BCh, DCH, FCP (SA), MMed (Int Med), Cert Pulmonology (SA) ;
T Nell,2 MB BCh, FC Rad Diag (SA), MMed (Rad) ; C Menezes,3 MD, MMed (Int Med), FCP (SA), DTM&H, Cert ID (SA), PhD ;
B F Jacobson,4 MB ChB, MMed (Haem), PhD, FRCS (Glasg), FC Path (SA) Haem ;
S Omar,5 MB ChB, FC Path SA Chem, DA (SA), Cert Critical Care (SA) ;
1 Division of Pulmonology, Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand and Chris Hani Baragwanath Academic
Hospital, Johannesburg, South Africa
2 Division of Diagnostic Radiology, Department of Radiation Sciences, Faculty of Health Sciences, University of the Witwatersrand and Chris Hani Baragwanath
Academic Hospital, Johannesburg, South Africa
3 Division of Infectious Diseases, Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand and Chris Hani Baragwanath
Academic Hospital, Johannesburg, South Africa
4 Division of Molecular Medicine and Haematology, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the
Witwatersrand, Johannesburg, South Africa
5 Division of Critical Care, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand and Chris Hani Baragwanath Academic
Hospital, Johannesburg, South Africa
Corresponding author: S A van Blydenstein (savanblydenstein@gmail.com)
Study synopsis
What the study adds. During the COVID‑19 pandemic, in a resource‑limited, high‑prevalence setting, lung ultrasound (LUS) patterns on
admission to hospital were used to distinguish between COVID‑19 and other causes in patients with hypoxaemic pneumonia. Patients with
right upper zone consolidation were more likely to have non‑COVID‑19 community‑acquired pneumonia (CAP) than COVID‑19 pneumonia.
Implications of the ndings. e admission LUS score was unable to discriminate between COVID‑19 pneumonia and non‑COVID CAP,
and did not correlate with the ratio of partial pressure of oxygen to fractional inspired oxygen, clinical severity or mortality. e pattern was
more valuable than the total LUS score in understanding the disease process.
AJTCCM VOL. 31 NO. 1 2025 35
ORIGINAL ARTICLES: RESEARCH
Lung ultrasound (LUS) has been used successfully for the identication
and follow‑up of the progression of lung pathology in COVID‑19.[1,2]
LUS outperforms chest radiography in identifying an alveolar pattern
of disease in pneumonia.[3] e benets of LUS over other radiological
modalities in COVID‑19 are that it is a bedside test, gives real‑time
data, can be performed by a single treating physician, thereby limiting
hazardous exposure to the patient, is repeatable and low in cost, and
has high diagnostic accuracy.[3,4] ese factors make LUS particularly
attractive as an imaging modality in a resource‑constrained
environment. Chest radiography and computed tomography (CT)
are both limited in the setting of COVID‑19, while infection control
is better managed through single‑machine use and a chlorhexidine‑
based cleansing protocol.[4]
Lung ndings on histological examination and CT in COVID‑19
are predominantly bilateral ground‑glass opacification (GGO),
peripheral consolidation, or a mixture of GGO and consolidation,
with occasional crazy paving (10%) and wedge‑shaped lesions.[5,6]
e preponderance of peripheral lesions enhances the suitability of
imaging by LUS. e common LUS ndings described in COVID‑19
pneumonia include bilateral B lines (separate or conuent) and
subpleural consolidation,[4,6] although these findings are less
accurate in the presence of interstitial lung disease and pulmonary
oedema.[7] In the acute phase of the illness, there is typical sparing
of areas between the various forms of B lines found, resulting in
bilateral patchy areas of inltrates.[6] It has been suggested that
during a peak of the pandemic, a normal LUS in a patient with
respiratory symptoms and no comorbid lung disease can be used
to rapidly exclude the requirement for a SARS‑CoV‑2 swab or
further testing for COVID‑19 pneumonia.[6,7] Pleural eusion is also
uncommon in the early phase of the disease, and its absence should
prompt consideration of an alternative diagnosis.[4] However, LUS
ndings are time dependent, and evolve, resulting in consolidation
and pleural eusion later during the course of the disease.[8]
LUS has also been shown to predict mortality, with scores of >18
(in a 12‑point LUS examination) associated with reduced survival.[2]
Szekely etal.[9] showed that LUS within the rst 24 hours of admission
improved prediction of the need for ventilation.
It was with the above in mind that the present study was
performed to compare LUS findings in patients with COVID‑19
and non‑COVID‑19 pneumonia, and to determine associations with
disease severity and survival, in the South African (SA) setting.
Methods
Study design and site
is was a prospective, observational study of two cohorts of adult
patients with hypoxaemic pneumonia (those with COVID‑19
pneumonia and those with non‑COVID‑19 community‑acquired
pneumonia (CAP)) in a South African hospital. Right heart
echocardiography ndings in the same cohorts of patients have been
reported previously.[10] Both articles form part of the rst author
(SAvB)’s PhD.
Study population
During working hours of weekdays, we screened all consecutive adult
patients who were under investigation for SARS‑CoV‑2 virus infection
and were admitted between 20 October 2020 and 11 March 2021.
Patients were included if they had hypoxaemic pneumonia, diagnosed
by a physician or with a chest radiograph, and met the criteria for
severe or critical illness. Severe illness was defined as oxygen
saturation (SpO2) ≤92% with a respiratory rate ≥25 breaths per
minute requiring supplemental oxygen support without the need for
invasive or non‑invasive ventilation. Critical illness was dened as
hypoxaemia and the need for additional ventilatory support, in the
form of non‑invasive or invasive ventilation. Patients were excluded
if they were pregnant or had known chronic lung disease, chronic
cardiac disease, or a history of pulmonary or cardiac surgery.
Study procedure
Patient demographic, clinical, laboratory and hospital survival data
were extracted from clinical notes. e Simplied Acute Physiology
Score (SAPS II)[11] and Sequential Organ Failure Assessment (SOFA)
score[12] were calculated from the clinical information at the time
of admission, and admission biomarkers were recorded. LUS was
performed as described below, and all patients were followed up for
survival at hospital discharge.
LUS was performed using a GE HealthCare Mindray M7 ultrasound
diagnostic system (GE Medical, China), with the patient in a supine or
semi‑recumbent position. Lesion locations were divided into six zones,
corresponding with lobes, according to the Bedside Lung Ultrasound in
Emergency (BLUE) protocol (upper, middle and lower on the right and
le), and corresponded to the semi‑quantitative LUS evaluation using
standardised points described in the BLUE protocol.[1] If both hands are
placed horizontally on the anterior chest, with the h nger below
and along the clavicle, and other hand next to it with one thumb over
the other, the standardised points are as follows: upper BLUE point at
the middle of the upper hand and lower BLUE point at the middle of
the lower palm, while the lower point is dened by the intersection of
a horizontal line at the level of the lower BLUE point and a vertical line
at the posterior axillary line. Alow‑frequency, curvilinear probe and
a high‑frequency linear probe were used. Allstudies were performed
by one pulmonologist trained in the BLUE protocol, and images were
stored. A study‑blinded radiologist with a special interest in LUS
reviewed the images, and any discrepancies were settled via consensus
between the pulmonologist and the radiologist. All reventive measures
for respiratory, droplet and contact isolation were adhered to. At the
end of each procedure, the ultrasound machine was cleaned with
chlorhexidine soap and water. Apoint scoring system was employed
by region and ultrasound pattern, with an LUS of 0 being normal,
and 18 being the worst LUS score. Lung lesions were graded in the
following categories: normal pattern (Alines, non‑signicant Blines
(<3)) = 0 points; Blines (≥3) = 1 point; BC (≥3 B lines, and very
small consolidations) =2points; ultrasound signs of consolidation,
e.g.hepatisation, shred sign (Cpattern) = 3 points.
Outcome measures
e primary outcome was describing the LUS ndings in COVID‑19
pneumonia and non‑COVID CAP with regard to type and extent of lung
lesions. Secondary outcomes included correlating the type and extent
of lung lesions with the ratio of partial pressure of oxygen to fractional
inspired oxygen (FiO2) (P/F ratio or Horowitz index), investigating the
relationship between LUS and inammation, and describing survival
in the two pneumonia groups.
36 AJTCCM VOL. 31 NO. 1 2025
ORIGINAL ARTICLES: RESEARCH
Statistical analysis
Study data were collected and managed using the REDCap (Research
Electronic Data Capture) online database manager[13,14] hosted at the
University of the Witwatersrand, Johannesburg. Statistical analyses
were performed using Statistica version 13.3(TIBCOSowareInc.,
USA). Continuous variables were expressed as medians with
interquartile ranges (IQRs), and proportions/percentages were used
for categorical variables. Continuous data were compared using the
Mann‑Whitney U‑test, while proportions were compared using the
χ2 test. A p‑value <0.05 was considered statistically signicant. e
relationships between LUS lesions and clinical parameters (severity
scores) and oxygenation were investigated using Spearman’s rank
correlation (Rho).
Ethical considerations
Approval was received from the University Human Research Ethics
Committee (Medical) (ref. no. M200728) (National Health Research
Database GP_202008_140). Written informed consent from the
patient or patient surrogate was obtained as per local ethics committee
guidelines.
Results
Patient characteristics
We enrolled 72 patients, of whom 48 had COVID‑19 pneumonia and
24 non‑COVID CAP. e COVID‑19 patients were signicantly older
than the non‑COVID group (median (IQR) 52 (42‑62.5) years v. 42.5
(36‑52.5) years, respectively; p=0.007) and had a lower prevalence
of HIV infection (25% v. 54%; p=0.01), a higher frequency of both
hypertension (54% v. 17%; p=0.002) and diabetes mellitus (19% v. 8%;
p=0.04), and a trend towards a lower admission severity of illness score
(SAPS II) (median (IQR) 18 (13‑31.5) v. 29 (17‑36.5); p=0.15). e
demographics and comorbidities of the cohort are set out in Table1.
Characterisation of LUS patterns, B lines v. C pattern
e overall frequency of LUS signs in both the right and le lungs is
shown in Figs1 and 2. e B‑line prole dominated over the Cprole
of consolidation in both the right and le lungs. A dominant B‑line
prole was more strongly associated with COVID‑19 pneumonia
than with non‑COVID CAP (relative risk (RR) 1.87; 95% condence
interval (CI) 1.36 ‑ 2.59 for the right lung and RR 1.36; 95%
CI1.03‑1.78 for the le lung).
Bilateral changes on LUS rather than unilateral or no changes
were strongly associated with COVID‑19 pneumonia (RR 1.55;
95% CI1.004‑2.387). A confluent B‑line pattern (ground‑glass
appearance) in the right upper lobe was signicantly associated with
COVID‑19 pneumonia compared with the C pattern (consolidation)
(RR 3.8; 95% CI1.7‑8.6).
Ultrasound lung score
ere were no statistically signicant dierences in median lung scores
between COVID‑19 pneumonia and non‑COVID CAP (median
(IQR) 8 (4‑11.5) v. 7.5 (4.5‑12.5), respectively).
LUS and P/F ratio
ere were 20 patients with severe hypoxaemia, dened as a P/F ratio
<100. irteen were COVID‑19 positive and 7 had non‑COVID CAP.
For patients with a P/F ratio <100, there was a trend to a lower LUS
score (≤10) in the COVID‑19 group compared with the non‑COVID
CAP group (χ2 = 3.52; p=0.06).
LUS and inammation
We entered LUS scores for each of the six zones and the total LUS
into a linear regression model to predict inammation based on the
C‑reactive protein (CRP) level. In the nal model that included ve
variables (right upper zone (RUZ), right middle zone (RMZ), le
middle zone (LMZ), le upper zone (LUZ) and total LUS score), higher
LUS scores (reective of greater changes) in the RUZ (p=0.04; 95%
CI0.008‑0.65) and LMZ (p=0.03; CI0.03‑0.94) were signicantly
associated with greater CRP values.
Mortality
ere was a trend towards lower severity of illness (SAPS II) scores
in the COVID‑19 group compared with the non‑COVID CAP group
(18 v. 29, respectively; p=0.15). The standardised mortality ratio
(SMR) was 1.3 (95% CI0.8‑3.4) for non‑COVID CAP, with an actual
mortality of 12.5% and a predicted mortality based on the SAPS II
of 9.7% (95% CI3.7‑15.7). e SMR was 9.3 (95% CI5.1‑54.2)
for COVID‑19 pneumonia, with an actual mortality of 27.1% and a
predicted mortality based on the SAPS II of 2.9% (95% CI0.5‑5.3).
We performed logistic regression analysis using six variables:
a ix‑zone LUS, oxygenation (P/F ratio), severity of illness (SAPS II),
lactate, ventilation (partial pressure of carbon dioxide (PaCO2)), and
COVID‑19 status. A higher SAPS II (RR 1.11; 95% CI1.02‑1.21) and
a lower total LUS score indicating B lines v. consolidation (RR 0.80;
95% CI0.65‑0.99) were associated with mortality.
Discussion
The main finding of this study was that the BLUE protocol was
useful in describing COVID‑19 pneumonia. e type of LUS prole
(Blines with and without subpleural consolidations), the widespread
distribution (bilateral changes), and the specic regional ultrasound
ngerprint (ground‑glass conuent/coalescent B lines in the RUZ)
were all important in characterising COVID‑19 pneumonia and
dierentiating it from non‑COVID CAP. Our ndings of bilateral
interstitial syndrome are consistent with existing literature on LUS
presentation in COVID‑19, as rst recognised at the beginning of the
pandemic and in more recent data.[4,15‑21]
Compared with COVID‑19 pneumonia patients, non‑COVID CAP
patients were signicantly younger, with a higher HIV‑positivity rate
and lower prevalences of hypertension and diabetes, in keeping with
established risk factors for severe COVID‑19 pneumonia.[22] ere
was a clinically signicant trend towards higher severity of illness
scores (SAPS II) in the non‑COVID CAP group, as well as higher
D‑dimer levels, indicating that these patients presented on admission
with more organ dysfunction than the COVID‑19 group. Severe acute
respiratory distress syndrome was present in ~30% of both groups,
indicating similar admission respiratory compromise.
Use of the LUS score in differentiating COVID‑19 from
non‑COVID pneumonia has been described as having high
sensitivity and varying specificity,[16,23‑26] the latter probably
dependent on the background prevalence of COVID‑19 at the
time of the studies. LUS scores vary according to the number of
AJTCCM VOL. 31 NO. 1 2025 37
ORIGINAL ARTICLES: RESEARCH
zones scanned and protocols applied, but in confirmed COVID‑19,
higher LUS scores are associated with increasing severity. Studies
conducted in the pre‑vaccine period have compared the LUS scores
and characterisation of COVID‑19 compared with non‑COVID
pneumonia[1,4,16,18,23‑34] in varying detail, with most studies
favouring more descriptive terms in addition to the LUS score,
to show a better picture of the lung pathology.[4,16,18,23,27,29‑31,33] Our
findings demonstrate a predominance of B lines with and without
subpleural consolidations in COVID‑19. Furthermore, we found
a discriminating finding between the two types of pneumonia:
RUZ confluent B lines predicted COVID‑19 as the cause of the
pneumonia, compared with finding consolidation in the same zone
(RUZ), which predicted non‑COVID pneumonia, assisting in rapid
clinical discrimination on admission in high COVID‑19 prevalence
settings. There was a trend towards significance in the finding that
the absence of ultrasound findings in the left chest conferred an
increased RR for COVID‑19 pneumonia. An SA study looking
at severe COVID‑19 pneumonia chest radiographs consistently
found sparing of the LUZ.[35] Postulated reasons include the slight
hypoperfusion of the left lung compared with the right lung, and
considering that COVID‑19 causes endothelial and pulmonary
microvascular injury, this could translate to more significant
pathology in areas that are better perfused,[35] with upper zones
relatively less perfused than lower zones. Furthermore, Buckley
etal.[35] suggest that differences in the lymphatic drainage between
the right and left upper lobes could contribute to the sparing of
the LUZ.[35] The present study did not find large pleural effusions
in any COVID‑19 patients, in keeping with other studies showing
absence or rarity of pleural effusions in early stages of COVID‑19
pneumonia,[2,4,8] suggesting that the presence of a large pleural
effusion on admission should prompt the clinician to consider an
alternative diagnosis.
The relationship between total LUS score and oxygenation
(P/Fratio) was interesting. In comparison with the non‑COVID
CAP group, there was a trend to lower LUS scores in the COVID‑19
pneumonia group. is nding is likely to be a result of the weighting
of B‑line changes as opposed to consolidation, with the latter given
a higher score. Rather than a lesser degree of ultrasound ndings in
more hypoxaemic patients, it is likely to reect a relationship between
a B‑line prole and hypoxaemia compared with consolidation in this
early admission period. ere are few studies looking at LUS scores
and oxygen requirements in both COVID‑19 and non‑COVID
pneumonia, with one having normal oxygenation in both groups
(but COVID‑19 lower than non‑COVID) and the other showing an
inverse relationship between the P/F ratio and nding of subpleural
consolidations, although specic lung zones were not reported.[5,24]
ere are studies supporting the inverse relationship between LUS
score and oxygenation, but there is heterogeneity with regard to how
oxygenation was assessed and described.[2,4,8,16,21,24,36‑44] Some studies
found that patients with COVID‑19 pneumonia had a lower SpO2
than those with non‑COVID pneumonia, but this was not clinically
signicant, as both groups had normal oxygenation,[24,45] whereas
Table1. Patient characteristics
Vari able
Total
(N=72), n (%)†
Non‑COVID‑19 pneumonia
(n=24), n (%)†
COVID‑19 pneumonia
(n=48), n (%)†p‑value
Age (years), median (IQR) 48.5 (40‑58) 42.5 (36‑52.5) 52 (42‑62.5) 0.007*
Male 32/72 (44) 12/24 (50) 20/48 (42) 0.5
Comorbidities
HIV 25/72 (35) 13/24 (54) 12/48 (25) 0.01*
Hypertension 30/72 (42) 4/24 (17) 26/48 (54) 0.002*
Diabetes mellitus 11/70 (16) 2/24 (8) 9/48 (19) 0.04*
Smoker 15/72 (21) 7/24 (29) 8/48 (17) 0.21
SAPS II, median (IQR) 21 (14‑34) 29 (17‑36.5) 18 (13‑31.5) 0.15
SOFA score, median (IQR) 2 (2‑4) 2.5 (2‑4) 2 (2‑4) 0.36
Lactate (mmol/L), median (IQR) 1.8 (1.2‑2.4) 2.2 (1.7‑3.2) 1.6 (1.1‑2.4) 0.03*
PaO2 (mmHg), median (IQR) 45 (31‑62) 43 (29‑57) 46 (32‑63) 0.47
PaCO2 (mmHg), mean (SD) 37 (7.4) 36 (9.4) 37 (8.5) 0.83
P/F ratio
Median (IQR) 132 (93‑192) 143 (96‑218) 126 (81‑183) 0.62
≤100% 20/72 (28) 7/24 (29) 13/48 (27) 0.85
101‑200% 34/72 (47) 10/24 (42) 24/48 (50) 0.5
201‑300% 15/72 (21) 6/24 (25) 9/48 (19) 0.54
>300% 3/72 (4) 1/24 (4) 2/48 (4) 1
CRP (mg/L), median (IQR) 128 (60.5‑211) 106 (63‑225) 132.5 (56‑192) 0.92
D‑dimers (mg/L), median (IQR) 1.15 (0.38‑3.56) 2.08 (1.08‑3.84) 0.82 (0.35‑3.18) 0.02*
Total LUS score, median (IQR) 8 (4‑12) 7.5 (4.5‑12.5) 8 (4‑11.5) 0.56
IQR = interquartile range; SAPS II = Simplied Acute Physiology Score; SOFA = Sequential Organ Failure Assessment; PaO2 = partial pressure of oxygen; PaCO2 = partial pressure of carbon dioxide;
P/F ratio = ratio of PaO2 to fractional inspired oxygen (Horowitz index); CRP = C‑reactive protein; LUS = lung ultrasound.
*Statistically signicant (p<0.05).
†Except where otherwise indicated.
38 AJTCCM VOL. 31 NO. 1 2025
ORIGINAL ARTICLES: RESEARCH
other studies described a higher LUS score
as being associated with a lower SpO2 or
SpO2/FiO2 ratio.[2,40,44] When the P/F ratio is
used, or a measurement including the P/F
ratio, generally the higher the LUS score,
the lower the P/F ratio,[8,19,41] with one study
showing no correlation with P/F and LUS
score.[8] is study did, however, describe an
association between the BLUE protocol and
the P/F ratio.[8] Studies have also described
a higher LUS score as being associated with
severe/critical illness (criteria including
hypoxaemia of some degree, but also other
factors, including shock, or need for organ
support or intensive care).[37,38,42] Our study
demonstrated an inverse relationship
between the P/F ratio and the B‑line pattern
in the LMZ for the COVID‑19 group,
suggesting that once the middle zone has
developed alveolar‑interstitial syndrome
in COVID‑19 pneumonia, the patient is
likely to be hypoxaemic with diuse disease
involvement. If specific LUS findings
associated with hypoxaemia in COVID‑19
pneumonia are to be considered, these
would include B lines[31,40] and subpleural
consolidations,[4] but there are few data
exploring the changes in dierent lung areas
associated with severity of hypoxaemia in
COVID‑19 pneumonia.
We found a relationship between LUS and
inflammation. More specifically, regional
changes (RUZ and LMZ) and ultrasound
scores were directly associated with CRP
levels, indicating greater inammation. Pare
etal.[24] found a non‑significant increased
CRP level in COVID‑19 patients compared
with non‑COVID, but this nding was not
related to the LUS score or to a specic LUS
nding. In COVID‑19 patients, a higher LUS
score has been associated with increased
CRP[2,21,46] and interleukin 6 levels.[43] Specic
LUS ndings associated with higher CRP in
patients with COVID‑19 pneumonia include
consolidation as opposed to B lines,16] which
could suggest a more severe form of disease,
or a later presentation with complications.
The mortality rate for COVID‑19
pneumonia in the present study was high
(27%) compared with non‑COVID CAP
(12%), and the SMR indicates that the
actual mortality was higher than predicted
for COVID‑19 pneumonia but not for
non‑COVID CAP, despite the two groups
being similar in terms of oxygenation, and
the COVID‑19 group having a clinically
signicantly lower SAPS II.
We included clinically meaningful
parameters (LUS score, oxygenation (P/F
ratio), severity of illness (SAPS II), lactate,
ventilation (PaCO2), and COVID‑19 status)
to build a logistic regression, and found a
higher SAPS II and a LUS score in keeping
with B lines rather than consolidation to be
predictive of poor outcome.
is study suggests that B lines in the RUZ
are associated with a higher mortality rate than
the presence of consolidation in the RUZ. We
attribute this nding to disease progression
and expansion of the pathology over time, with
the presence of B lines in the RUZ possibly
representing more advanced COVID‑19
disease. Some pre‑vaccine studies showed that
expansive lung involvement was associated
with a worse prognosis,[38,47] with more
demonstrating that a higher baseline LUS score
is associated with higher mortality.[2,38,39,43,48]
Literature describing LUS patterns is similar
to our ndings, where a coalescent B pattern
was associated with a poorer prognosis,[17] and
in a study that did not compare COVID‑19
with non‑COVID pneumonia, the presence of
consolidation in COVID‑19 pneumonia was
associated with mortality.[16]
Study limitations
This was a single‑centre prospective,
observational study with a relatively small
18
16
14
12
10
8
6
4
2
0
Non-COVID COVID
B lines >3 B lines BC C pattern
Lung score
RUZ RMZ RLZ RUZ RMZ RLZ
2
7 7
1
7
8
7
3
4
15
16
3
10
17
3
14 14
7
Fig.1. Right lung ultrasound ndings. (R = right; U = upper; Z = zone; M = middle; L = lower;
BC = ≥3 B lines, and very small consolidations.)
18
16
14
12
10
8
6
4
2
0
Non-COVID COVID
B lines >3 B lines BC C pattern
Lung score
LUZ LMZ LLZ LUZ LMZ LLZ
13
15
6
8
15
17
7
17
7
4
6 6 4
7
5 5 5
6
Fig.2. Le lung ultrasound ndings. (L = le; U = upper; Z = zone; M = middle; L = lower; BC
= ≥3 B lines, and very small consolidations.)
AJTCCM VOL. 31 NO. 1 2025 39
ORIGINAL ARTICLES: RESEARCH
sample size. Despite being unable to control for biases, we did have a
control group to compare against, which is lacking in many observational
studies on this topic. While LUS only examines the peripheral pulmonary
parenchyma, and as such no conclusions regarding the central parenchyma
can be made, no comparisons were made with other imaging modalities.
LUS is operator dependent. We did mitigate against this by having a
single clinician perform all the imaging. Furthermore, a study‑blinded
radiologist with a special interest in LUS also interpreted the images,
with any dierences being resolved by consensus. LUS was performed
in hypoxaemic patients, either under investigation for or positive for
COVID‑19, which could be a source of bias for the interpretation of
pathology ndings, as it could decrease the specicity of the LUS in
COVID‑19 in a non‑pandemic scenario.
Conclusions
Admission LUS scores were unable to discriminate between
COVID‑19 and non‑COVID pneumonia, and did not correlate
with the P/F ratio, clinical severity or mortality. Survival is reduced
in COVID‑19 pneumonia compared with non‑COVID CAP. LUS
patterns could discriminate between COVID‑19 and non‑COVID,
in that patients with RUZ consolidation are more likely to have
non‑COVID than COVID‑19 pneumonia. Finding a B pattern as
opposed to consolidation was associated with mortality.
Data availability. e datasets generated and analysed during the present
study are available from the corresponding author (SAvB) on reasonable
request. Any restrictions or additional information regarding data access
can be discussed with the corresponding author.
Declaration. e research for this study was done in partial fullment of the
requirements for SAvB’s PhD degree at the University of the Witwatersrand.
Acknowledgements. None.
Author contributions. SAvB: conception, design of the work, data
collection and sample collection, interpretation of data, draed the article,
substantively revised it and approved the submitted version, and agrees
both to be personally accountable for the author’s own contributions and
to ensure that questions related to the accuracy or integrity of any part
of the work, even ones in which the author was not personally involved,
are appropriately investigated, resolved, and the resolution documented
in the literature. CM: conception, design of the work, substantively
revised the article and approved the submitted version, and agrees both
to be personally accountable for the author’s own contributions and to
ensure that questions related to the accuracy or integrity of any part of
the work, even ones in which the author was not personally involved, are
appropriately investigated, resolved, and the resolution documented in the
literature. BFJ: conception, substantively revised the article and approved
the submitted version, and agrees both to be personally accountable for
the author’s own contributions and to ensure that questions related to the
accuracy or integrity of any part of the work, even ones in which the author
was not personally involved, are appropriately investigated, resolved, and
the resolution documented in the literature. SO: conception, design of the
work, analysis and interpretation of data, substantively revised the article
and approved the submitted version, and agrees both to be personally
accountable for the author’s own contributions and to ensure that
questions related to the accuracy or integrity of any part of the work, even
ones in which the author was not personally involved, are appropriately
investigated, resolved, and the resolution documented in the literature.
TN: interpretation of data, substantively revised the article and approved
the submitted version, and agrees both to be personally accountable for
the author’s own contributions and to ensure that questions related to the
accuracy or integrity of any part of the work, even ones in which the author
was not personally involved, are appropriately investigated, resolved, and
the resolution documented in the literature.
Funding.None.
Conicts of interest.None.
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Received 23 January 2024. Accepted 6 January 2025. Published 28 March 2025.
