Introduction
Pleural effusions represent a very common diagnostic task to the physician. A correct diagnosis of the underlying disease is essential to the rational management.1 Normally the pleural space contains only a few millimetres of fluid. Indeed pleural effusion must be regarded as a trivial event but as a sign of major disorder or disease.2
The first diagnostic step is the identification of pleural effusions as either a transudate or exudates. This is useful because it indicates the pathophysiological mechanisms involved. Exudates are secondary to alteration of capillary permeability or lymphatic drainage. Transudates are due to either alterations of hydrostatic and / or osmotic pressure in pleural capillaries or to a fluid passing from the peritoneal cavity via diaphragmatic defects.
If an exudate is present further diagnostic procedures and tests are imperative for definitive diagnosis and specific therapy. On the other hand if the fluid is clearly a transudate one need not worry about manoeuvres directed at the pleura and need to treat only the congestive cardiac failure, nephrosis, cirrhosis or hypoproteinemia.3 Over the years many criteria have been developed by various workers for separation of exudates and transudates.
Objective of the study
To study the diagnostic value of Pleural fluid Cholesterol in differentiating transudative and exudativepleural effusions.
Method of collection of data
Sample size
Using expected incidence of exudates cases among pleural effusion as 69.4%, expected sensitivity as 88%, expected specificity as 100% and desired precision as +/-10%,
The minimum sample is 60.
This sample size will give the precision of 10%for both sensitivity and specificity.
Formula used:
N=z2 (1-p)/d2
Z-value of z statistic at 5% level of significance
d-margin of error
p-expected incidence rate
Results and Observation
The present study was undertaken in 60 cases of Pleural Effusion over a period of 2 and half years from November 2016 to July 2018, the results of which are given below.
Table 1
Age and sex distribution
|
Age (years) |
Male |
Female |
p value |
||
|
N |
% |
N |
% |
||
|
18-20 |
1 |
2.6 |
0 |
0.0 |
0.641 |
|
21-30 |
5 |
13.2 |
4 |
18.2 |
|
|
31-40 |
8 |
21.1 |
7 |
31.8 |
|
|
41-50 |
12 |
31.6 |
3 |
13.6 |
|
|
51-60 |
8 |
21.1 |
5 |
22.7 |
|
|
>60 |
4 |
10.5 |
3 |
13.6 |
|
|
Total |
38 |
100.0 |
22 |
100.0 |
|
The age of the patient in this study ranged from 18 years to 75 years. 1 patient was 18 years, 9 patients were under 21-30 years, 15 patients were under 31-40 years, 15 patients were under 41-50 years, 13 patients were under 51-60 years, 7 patients were above 60 years. Out of 60 patients there were 38 males and 22 females.Table 1
Table 2
Distribution of exudates and transudate according to lights criteria
|
Based on lights criteria |
N |
% |
|
Exudate |
46 |
76.7 |
|
Transudate |
14 |
23.3 |
|
Total |
60 |
100 |
Based on Lights criteria, out of 60 patients 46 were exudates (76.7%) and 14 were transudates (23.3%).Table 2
Table 3
Distribution of exudates and transudate according to pleural fluidcholesterol criteria
|
Based on cholesterol criteria |
N |
% |
|
Exudate |
45 |
75 |
|
Transudate |
15 |
25 |
|
Total |
60 |
100 |
Based on pleural cholesterol level criteria, out of 60 patients 45(75%) were exudates and 15(25%) were transudates.Table 3
Table 4
Distribution of symptoms in pleural effusion at presentation
Cough was present in 50 patients (83.3%), fever in 22 patients (36.7%), chest pain in 34 patients (56.7%), dyspnoea in 47(78.3%), swelling of limbs and abdominal distension each in 10 patients (16.7%), facial puffiness in 6 patients, loss of appetite in 60 patients (100%), loss of weight in 40 patients (66.7%).Table 4
Table 5
Distribution of signs in pleural effusion at presentation
|
Clinical signs |
Number (n=60) |
Percentage |
|
1. Stony dullness |
60 |
100 |
|
2. Absent breath sound |
50 |
83.3 |
|
3. Decreased VF/VR |
52 |
86.7 |
|
4. Mediastinal shift |
50 |
83.3 |
|
5. Pleural rub |
4 |
6.6 |
|
6. Crepitations |
5 |
8.3 |
Stony dullness in 60 patients (100%), Decreased / absent breath sounds in 50 patients (83.3%), Mediastinal shift in 33 patients (83.3%), Decreased VF/VR in 52 patients (86.7%), Pleural rub in 4 patients (6.6%), Crepitations in 5 patients (8.3%).Table 5
Table 6
Pleural effusion right and left side distribution
|
Side of effusion |
Number ( n=60) |
Percentage |
|
Right |
36 |
60.0 |
|
Left |
19 |
31.7 |
|
Bilateral |
5 |
8.3 |
Out of 60 patients, 36 had right sided effusion, 19 had left sided effusion, 5 patients had bilateral pleural effusion.Table 6
Table 7
Result of sputum AFB
|
Sputum AFB |
Total |
P value |
|
|
N |
% |
||
|
Negative |
28 |
46.7 |
0.232 |
|
Positive |
32 |
53.3 |
|
|
Total |
60 |
100.0 |
|
In the study group of 60 patients, sputum AFB was positive in 32 (53.3%) patients and 28 (53.3%) patients had sputum AFB was negative.Table 7
Table 8
Cytology of pleural effusion
|
Cytology |
Total |
p value |
|
|
N |
% |
||
|
Lymphocytes + Mesothelial cells |
3 |
5.0 |
0.476 |
|
Predominantly lymphocytes |
42 |
70.0 |
|
|
Predominantly neutrophils |
15 |
25.0 |
|
|
Total |
60 |
100.0 |
|
Out of 60 patients, 3 patients had lymphocytes plus mesothelial cells, 42 patients had predominantly lymphocytes and 15 patients had predominantly neutrophils.Table 8
Table 9
Distribution of pleural protein
|
Pleural Protein (gram/dl) |
Number (n=60) |
|
1-2 |
6 |
|
2-4 |
16 |
|
4-6 |
34 |
|
>6 |
4 |
|
Total |
60 |
The above table shows the values of pleural protein. 6 patients had pleural protein values ranging from 1-2 gram/dl, 16 patients of pleural protein ranging from 2-4 gram/dl, 34 patients ranging from 4-6 gram/dl and 4 patients had protein levels above 6 gram/dl.Table 9
Table 10
Distribution of pleural cholesterol
|
Pleural Cholesterol |
Number (N=60) |
|
<45 mg/dl |
15 |
|
>45 mg/dl |
45 |
|
Total |
60 |
15 patients had pleural cholesterol levels less than 45 mg/dl and 45 patients had cholesterol level above 45 mg/dl.Table 10
Table 11
Biochemical analysis of pleural effusion
Note: * significant at 5% level of significance (p<0.05).
The p value of serum protein is 0.215, pleural protein is <0.001, pleural sugar is <0.001, pleural cholesterol is <0.001, pleural fluid protein: serum protein is <0.001. P value of <0.001 is statistically significant.Table 11
Table 12
Comparison of exudative and transudative pleural effusion according to pleural fluid cholesterol criteria and lights criteria
|
|
According to pleural fluid cholesterol criteria (N=60) |
According to lights criteria (N=60) |
P value |
||
|
|
N |
% |
N |
% |
|
|
Exudate |
45 |
75.0 |
46 |
76.66 |
<0.001* |
|
Transudate |
15 |
25.0 |
14 |
23.33 |
|
|
Total |
60 |
100.0 |
60 |
100.0 |
|
Note: * significant at 5% level of significance (p<0.05)
Based on lights criteria 46 patients were exudate and 14 patients were transudative pleural effusion, based on cholesterol criteria 45 patients were exudative and 15 were transudative pleural effusion.Table 12
The p value is < 0.001 which is statistically significant.
Table 13
Sensitivityanalysis of pleural cholesterol criteria
Table 14
Biochemical analysis of pleural effusion
According to Lights Criteria, the mean serum protein is 5.7±1.0 in exudates and 6.1±1.1 has p value of 0.215. The mean pleural protein is 4.7±1.0 in exudates and 2.4±0.9 has p value of 0.001. The mean pleural sugar is 68.2±40.1 in exudates and 126.7±75.9 has p value of 0.001.The mean pleural protein: serum protein is 0.8±0.2 in exudates and 0.3± 0.1 has p value of 0.001. According to pleural cholesterol criteria, the mean pleural cholesterol is 78.2±23.7 in exudates and 21.9±9.2 and has p value of 0.001 which is statistically significant.Table 14
Pleural fluid cholesterol
Table 15
Comparison of pleural fluid cholesterol values between the studies
|
S.No |
Authors |
Sensitivity |
Specificity |
PPV |
NPV |
Accuracy |
|
1 |
Hamm 4 |
93.5 |
100 |
100 |
91 |
96 |
|
2 |
Valdes |
92.5 |
87.6 |
95 |
80 |
91.3 |
|
3 |
Ram |
96 |
93 |
96 |
92.6 |
95 |
|
4 |
B N Mohaptra |
92 |
100 |
100 |
99 |
93 |
|
5 |
Burgess |
54 |
92.2 |
87.3 |
50 |
66 |
|
6 |
Present study |
97.8 |
100 |
100 |
93.3 |
98.3 |
Discussion
A total of 60 patients were taken up for this study. Out of 60, 46 were exudates and 14 were transudates. Among 46 exudates, 40 were tubercular effusions, 5 patients were synpneumonic effusion and 1 patient with malignant effusion.
Among 14 transudative, 7 patients were congestive cardiac failure, 7 patients were cirrhosis.
Age and sex
The age of the patient in this study ranged from 18 years to 75 years. 1 patient was 18 years, 9 patients were between 21-30 years, 15 patients were between 31-40 years, 15 patients were between 41-50 years, 13 patients were between 51-60 years and 7 patients were above 60 years. Out of 60 patients, males were 38 and females were 22.
Presenting symptoms
Cough was present in 50 patients (83.3%), fever in 22 patients (36.7%), chest pain in 34 patients (56.7%), dyspnoea in 47 (78.3%), swelling of limbs and abdominal distension each in 10 patients (16.7%), facial puffiness in 6 patients, loss of appetite in 60 patients (100%), loss of weight in 40 patients (66.7%).
Signs
Mediastinal shift is seen in 50 patients opposite to the pleural effusion. Over affected side of chest, fullness of chest in 48 patients, decreased chest movements in 50 patients, expansion of chest reduced in 50 patients, decreased vocal fremitus in 52 patients, stony dullness in 60 patients, absent breath sounds in 50 patients, decreased vocal resonance in 52 patients, pleural rub in 4 patients and Crepitations in 5 patients.
Side of pleural effusion
Out of 60 patients, 36 had right side effusion, 19 had left side effusion, and 5 patients had bilateral pleural effusion.
Sputum AFB analysis
In the study group of 60 patients, sputum AFB was positive in 32 (53.3%) patients and 28 (53.3%) patients had sputum AFB was negative.
Colour of pleural effusion distribution
Colour of pleural effusion 36 patients had amber colour, 18 patients had clear fluid, 4 patients had haemorrhagic and straw colour in 2 patients.
Cytology of pleural effusion
Out of 60 patients, 3 patients had predominantly lymphocytes plus mesothelial cells, 42 patients had predominantly lymphocytes and 15 patients had predominantly neutrophils.
USG analysis
In the study group of 60 patients, cirrhosis was present in 7 patients, hepatomegaly in 1 patient, ascites in 1 patient, and normal in 39 patients.
Biochemical analysis of pleural effusion
Hammfirst used pleural cholesterol as a parameter. In his study of 150 patients he found excellent results (Sensitivity 93%, Specificity 100%, Accuracy 96%). Following Hamm’s, 5 Valdes 6 aimed to validate this parameter. In his study of 74 patients pleural cholesterol had good resultsas shown in the above table. Similar results were obtained from studies by Ram7 in 100 patients and B N Mohaptra 8 in his study of 132 patients. The studies of Burgess and Remeroof 124 patients, results were in favour of lights criteria but they had less sensitivity, specificity and accuracy. As a result the present study of 60 patients which contains Pleural Cholesterol criteria has more sensitivity, specificity and accuracy when compared to other studies done by Burgess 9 and Remero4 which contains Lights criteria. The study shows that pleural fluid cholesterol criteria (cholesterol >45 mg/dl - exudate and cholesterol <45 mg/dl – transudate) constitute a useful tool for the separation of pleural effusions.
Conclusion
The pleural fluid cholesterol criteria were found to be the most efficient criteria.
Since this parameter involves the measurement of only pleural fluid values of cholesterol, it has following advantages
Economically, it reduces number of biochemical tests
Simpler, as there is no need to take simultaneous blood sample at the time of thoracocentesis.
It is concluded that the determination of pleural fluid cholesterol criteria can be included in routine analysis of pleural fluid samples in place of presently used Lights Criteria.
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