Ultrasound in predicting improvement in dyspnoea after therapeutic thoracentesis in patients with recurrent unilateral pleural effusion

Figures & data

Figure 1. Diaphragm movement during respiration measured by the area method: (a) Full inspiration, maximal area over the diaphragm; (b) Full expiration, minimal area over the diaphragm.

Figure 2. Flowchart showing the inclusion of patients.

Figure 3. Box plot showing patient perceived dyspnoea before and after thoracentesis measured by modified Borg scale (MBS). Wilcoxen signed rank test for p-values.

Table 1. Baseline characteristics of included patients.

Characteristic	Population n = 104
Age, years: mean (SD)	73 (10)
Sex: n (%)
Female	44 (42)
Male	60 (58)
Smoking: n (%)
Never	25 (24)
Ever	79 (76)
Pack years: median (IQR)	30 (15-44)
Comorbidities associated with dyspnoea*: n (%)	50 (48)
Aetiology of the pleural effusion^¤: n (%)
Malignant	75 (72)
Lung	37 (36)
Breast	12 (12)
Mesothelioma	12 (10)
Ovarian	3 (3)
Lymphoma	4 (4)
Uterus	1 (1)
Sarcoma	1 (1)
Kidney	2 (2)
GIST	1 (1)
Mb. Waldenström	1 (1)
Unknown primary tumour	1 (1)
Non-malignant:	29 (28)
Cardiac failure	10 (10)
Pleuritis	7 (7)
Hepatic insufficiency	2 (2)
Pulmonary embolism	1 (1)
Pulmonary hypertension	1 (1)
Kidney failure and pulmonary hypertension	1 (1)
Complicated parapneumonic effusion	2 (2)
Post CABG	1 (1)
Meig’s syndrome	1 (1)
Unknown	3 (3)
Volume drained, L: mean (SD)	1313 (668)
MRC: median (IQR)	4 (2-5)
Prior thoracenteses:
Number within one year: median (IQR)	3 (2-5)
Days since most recent: median (IQR)	20 (11-42)

*For further details see Appendix B.

^¤In 15 patients with unknown cause of pleural effusion at follow-up, the electronic patient file were assessed one year later do establish final cause.

Table 2. Correlation between different characteristics and having a clinical important improvement in dyspnoea measured by modified Borg scale (MBS), defined as a drop ≥ 1.

		Unadjusted		Adjusted
Characteristic	Responders/total	OR (95% CI)	p-value	OR (95% CI)	p-value
Subjects, n	55/104
Age, years		0.99 (0.95–1.03)	0.58
Female sex	25/44	1
Male sex	30/60	0.76 (0.35–1.66)	0.49
Never smoker	14/25	1
Ever smoker	41/79	0.85 (0.34–2.09)	0.72
Cause of effusion
Benign	14/29	1
Malignant	41/75	1.29 (0.55–3.05)	0.56
No comorbidity associated with dyspnoea	24/54	1
Comorbidity associated with dyspnoea	31/50	2.04 (0.93–4.47)	0.08
Characteristics before drainage:
Baseline level of dyspnoea:
MRC
1–3	25/44	1
4–5	30/46	2.47 (1.05–5.78)	0.04	1.62 (0.62–4.26)	0.33
MBS
0–3	22/58	1
4–10	33/46	4.15 (1.81–9.55)	<0.001	3.86 (1.42–10.50)	0.01
Diaphragm shape:
Domed	46/77	1
Non-domed	9/26	0.36 (0.14–0.90)	0.03	0.70 (0.23–2.18)	0.54
Diaphragm movement:
M-mode, cm		1.26 (0.76–2.08)	0.36
Area method, cm^2		1.04 (0.97–1.11)	0.25
Dichotomised M-mode
Impaired	22/42	1
Normal	32/58	1.12	0.78
Size of pleural effusion
Small	12/25	1
Moderate	35/60	1.51 (0.59–3.87)	0.38
Large	8/19	0.79 (0.24–2.62)	0.70
Effusion echogenicity:
Simple	27/53	1
Non-simple	28/51	1.17 (0.54–2.53)	0.69
No septations	46/81	1
Septations	9/23	0.49 (0.19–1.26)	0.14
No swirling sign	32/65	1
Swirling sign	23/39	1.48 (0.66–3.31)	0.34
No signs of trapped lung	43/75	1
Signs of trapped lung	12/29	0.53 (0.22–1.25)	0.15
Characteristics after drainage:
Diaphragm shape unchanged	48/83	1
Diaphragm shape normalised*	7/21	0.36 (0.13–1.00)	0.05
Not fully drained	24/56	1
Fully drained	31/48	2.43 (1.10–5.38)	0.03	2.86 (1.03–7.93)	0.04
Volume drained, L		1.13 (0.63–2.02)	0.68
Delta M-mode		1.13 (0.73–1.76)	0.58
Delta Area method		0.97 (0.93–1.02)	0.23

OR calculated by logistic regression.

*From inversed or flat diaphragm shape to domed.

Variables in multivariate analysis adjusted for variables with p < 0.05 in univariate analysis.

Table 3. Diaphragm shape before and after thoracentesis. N = 104.

	After
Before	Domed	Flat	Inversed	Not visualised*	Total
Domed	77	0	0	0	77
Flat	18	5	0	0	23
Inversed	3	0	0	0	3
Not visualised*	0	0	0	1	1
Total	98	5	0	1	104

*Patient with thorax deformity and pneumothorax.

Table 4. Diaphragm movement pre and post thoracentesis assessed by M-mode and area method. N = 104.

	Diaphragm movement
	M-mode, cm, mean (SD)	Area method, cm2, mean (SD)	Coefficient* (95%CI)	p-value*
The side of effusion
Before thoracentesis	1.3 (0.8)	8.6 (6.2)	0.06 (0.04–0.08)	<0.001
After thoracentesis	1.6 (1.0)	14.6 (9.7)	0.06 (0.05–0.09)	<0.001
Delta	0.3 (1.0)	6.5 (9.4)	0.06 (0.04–0.08)	<0.001
p-value^#	0.004	<0.001
The opposing side
Before thoracentesis	3.7 (1.4)	27.8 (10.3)	0.04 (0.01–0.07)	0.02
After thoracentesis	3.5 (1.6)	27.6 (10.7)	0.05 (0.01–0.08)	0.001
Delta	− 0.02 (1.3)	−0.3 (8.7)	0.03 (0.00–0.07)	0.05
p-value^#	0.91	0.79

*Correlation between M-mode and Area method, linear regression.

^#Between measurements before and after thoracentesis, paired t-test.

Table A. Modified Borg Scale (MBS).

0	No breathlessness at all
0.5	Very, very slight (just noticeable)
1	Very slight
2	Slight
3	Moderate
4	Somewhat severe
5	Severe
6
7	Very severe
8
9	Very, very severe (almost maximal)
10	Maximal
Medical Research Council dyspnoea scale (MRC)
1	No breathlessness except with strenuous exercise
2	Shortness of breath when hurrying on the level or walking up a slight hill
3	Walks slower than people of the same age on the level because of breathlessness or stops for breath while walking at own pace on the level
4	Stops for breath after walking about 100 metres or after a few minutes on the level
5	Too breathless to leave the house or breathless when dressing or undressing

Specification of comorbidities associated with dyspnoea, n = 50

Comorbidity	N (%)
Asthma	9 (8)
COPD*	18 (17)
Interstitial lung disease	2 (2)
Pulmonary lobectomy/pleurectomi	2 (2)
Heart failure	6 (6)
Former irradiation of the lung	15 (14)
Pulmonary tumour	7 (7)
Mamma tumour	8 (8)
Intrapulmonary tumour^§ = T4	34 (33)
Other	14 (13)
Cardiac dysfunctions not causing heart failure^#	7 (7)
Chronic back pain	3 (3)
Pulmonary hypertension	2 (2)
Ascites	1 (1)
Emphysema	1 (1)

*Chronic obstructive pulmonary disease.

^§T4 according to the TNM classification of lung cancer, 8^th edition: lung cancer = 25, breast cancer = 4, lymphoma = 1, ovarian cancer = 1, mesothelioma = 1, kidney cancer = 1, sarcoma = 1.

^#Atrial fibrillation, pericardial effusion, valve disease, recent pulmonary embolism.

Specification of aetiology of the pleural effusion, n = 104

Aetiology	N(%)
Malignant	75 (72)
Lung	37 (36)
Breast	12 (12)
Mesothelioma	12 (10)
Ovarian	3 (3)
Lymphoma	4 (4)
Uterus	1 (1)
Sarcoma	1 (1)
Kidney	2 (2)
GIST	1 (1)
Mb. Waldenström	1 (1)
Unknown primary tumour	1 (1)
Non-malignant:	29 (28)
Cardiac failure	10 (10)
Pleuritis	7 (7)
Hepatic insufficiency	2 (2)
Pulmonary embolism	1 (1)
Pulmonary hypertension	1 (1)
Kidney failure and pulmonary hypertension	1 (1)
Complicated parapneumonic effusion	2 (2)
Post CABG	1 (1)
Meig’s syndrome	1 (1)
Unknown	3 (3)

Selected variables by completion of drainage (fully drained vs. not fully drained)

	Domed = 77	Non-domed = 26	p-value*
Comorbidity associated with dyspnoea, n(%)	40 (52)	10 (38)	0.24
MBS, n(%)
0–3	40 (52)	18 (69)
4–10	37 (48)	8 (31)	0.12
Size of pleural effusion
Small	23 (30)	2 (8)
Moderate	44 (57)	15 (58)
Large	10 (13)	9 (34)	0.01
Signs of trapped lung, n(%)	17 (22)	12 (46)	0.02
Volume drained, ml, mean (SD)	1190 (595)	1719 (704)	<0.001
Fully drained, n(%)	44 (57)	4 (15)	<0.001

P-values by Chi2 or Fisher’s exact test in categorical variables and t-test in continuous variables.

Selected variables by completion of drainage (fully drained vs. not fully drained)

	Fully drained, n = 48	Not fully drained, n = 56	p-value
Comorbidity associated with dyspnoea, n(%)	27 (56)	25 (45)	0.12
Baseline MBS, n(%)
0–3	27 (56)	31 (55)
4–10	21 (44)	25 (45)	0.93
Size of pleural effusion
Small	8 (14)	17 (35)
Moderate	31 (55)	29 (60)
Large	17 (30)	2 (4)	<0.001
Signs of trapped lung, n(%)	5 (10)	24 (43)	<0.001
Volume drained, ml, mean (SD)	1233 (64)	1381 (108)	0.26
Responders, n(%)	31 (65)	24 (43)	0.03
Change in MBS, mean (SD)	1.5 (2.8)	0.7 (2.7)	0.13

P-value by Chi2 or Fisher’s exact test in categorical variables and t-test in continuous variables.

Selected variables by signs of trapped lung (n = 104)

	Signs of trapped lung n = 29	No signs of trapped lung n = 75	p-value
Characteristics:
Age (mean, SD)	72.3 (7.7)	74.4 (11.0)	0.36
Sex, female	13 (45)	31 (41)	0.75
Ever smoker	20 (69)	59 (79)	0.30
malignant	25 (86)	50 (67)	0.05
comorbidity	13 (45)	37 (49)	0.68
Number within one year: median (IQR)	3 (2-4)	3 (2-5)	0.55
Days since most recent: median (IQR)	15 (10-31)	21 (12-42)	0.35
Before drainage:
Baseline level of dyspnoea:
MRC
1–3	14 (52)	30 (48)
4–5	13 (48)	33 (52)	0.71
MBS
0–3	17 (59)	41 (55)
4–10	12 (41)	34 (45)	0.72
Diaphragm shape:
Domed	17 (58)	60 (81)
Non-domed	12 (41)	14 (19)	0.02
Diaphragm movement:
M-mode, cm, mean(SD)	1.0 (0.9)	1.4 (0.7)	0.05
Area method, cm^2, mean(SD)	7.1 (6.5)	9.2 (6.1)	0.13
Dichotomised M-mode
Impaired	18 (67)	24 (33)
Normal	9 (33)	49 (67)	0.002
Size of pleural effusion
Small	5 (17)	20 (27)
Moderate	14 (48)	46 (61)
Large	10 (34)	9 (12)	0.03
Effusion echogenicity:
Simple	10 (34)	43 (57)
Non-simple	19 (66)	32 (43)	0.04
No septations	18 (62)	63 (84)
Septations	11 (38)	12 (16)	0.02
No swirling sign	17 (59)	48 (64)
Swirling sign	12 (41)	27 (36)	0.61
After drainage:
Diaphragm shape unchanged	20 (69)	63 (84)
Diaphragm shape normalised*	9 (31)	12 (16)	0.09
Fully drained	5 (17)	43 (57)	<0.001
Volume drained, L	1214 (733)	1351 (642)	0.35
Delta M-mode, mean(SD)	0.2 (1.0)	0.3 (1.0)	0.69
Delta Area method, mean(SD)	4.0 (7.4)	7.6 (10.0)	0.10
Responder^#, n(%)	12 (41)	43 (57)	0.14

*From inversed or flat diaphragm shape to domed.

^#Defined by a clinical important improvement in dyspnoea measured by modified Borg scale (MBS), defined as a drop ≥ 1.

P-value by Chi2 or Fisher’s exact test in categorical variables and t-test in continuous variables.