RU2523672C1 - Method for determining clinical probability of pulmonary artery thromboembolia - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention can be used for determining a clinical probability of developing pulmonary artery thromboembolia (PATE). There are determined the age, the body weight index (BWI) and clinical values: laboured breathing, tachypnea, tachycardia, symptoms of deep venous thrombosis. Each clinical value is appraised by points: symptoms of deep venous thrombosis as 3 points, laboured breathing as 1 point, tachycardia as 1.5 points, tachypnea as 1.5 points. The derived points of the specific patient are summed up, and a total score is used to calculate P1 and P2 values. The P1 and P2 values are calculated as follows: P1=-34.2+0.28×age+2.17×BWI+0.05×(total score of the clinical values), P2=-41.8+0.30×age+2.41×BWI+0.55×(total score of the clinical values). If P1>P2, a low probability of PATE is stated, while P1<P2 shows a high probability of PATE.

EFFECT: method enables the high-accuracy determination of the probability of developing PATE that is caused by taking into account a complex of significant risk factors of the developing disease.

2 tbl, 2 ex

Description

The invention relates to medicine and can be used to clinically determine the likelihood of developing pulmonary embolism (pulmonary embolism).

Pulmonary embolism as a cause of death in patients with cardiovascular disease takes third place after coronary heart disease and stroke [1, 2]. It has been established that among patients who died from pulmonary embolism, the estimated diagnosis of pulmonary embolism is established during life only in 30-45% of cases [3]. This means that other patients die without receiving adequate anticoagulant therapy. Currently, highly sensitive and highly specific diagnostic methods for pulmonary embolism are introduced into clinical practice: ventilation-perfusion scintigraphy, spiral computed tomography angiopulmonography, direct angiopulmonography. However, the presence of such methods does not solve the problem of underdiagnosis of pulmonary embolism [3]. This is due to the insufficient effectiveness of the clinical diagnosis of pulmonary embolism due to polymorphism of clinical signs and the absence of pathognomic symptoms.

One of the ways to solve the problem of increasing the efficiency of clinical diagnosis of pulmonary embolism is a clinical assessment of the probability of pulmonary embolism, based on a combined assessment of risk factors for pulmonary embolism and some clinical signs.

There are several ways to assess the clinical likelihood of developing pulmonary embolism by assessing risk factors and clinical symptoms, which use a scoring of the contribution of each trait. The most famous are the Wells scale [4] and the Miniati scale [5].

A method for assessing the risk of developing pulmonary embolism - the Miniati scale for assessing the clinical likelihood of pulmonary embolism takes into account the clinical and instrumental signs of pulmonary embolism. Among the clinical signs, the sudden development of shortness of breath, chest pain, fainting are analyzed. Signs of pulmonary embolism obtained by instrumental methods of research, which are included in the scale, include overload of the right ventricle diagnosed by ECG, amputation of the roots of the lungs, local oligemia according to x-ray examination. For a high probability of pulmonary embolism (90%), according to this scale, one of the clinical symptoms and two symptoms obtained by instrumental examination correspond. The probability of pulmonary embolism is assessed as moderate (50%) in the presence of one of the clinical symptoms and in the absence of instrumental signs of pulmonary embolism. The probability of pulmonary embolism is considered low in the absence of clinical symptoms or, if their presence can be explained by other diseases, and in the absence of signs of pulmonary embolism in an instrumental study.

The method described above does not take into account the influence of factors such as age, the presence of excess body weight. To date, it has been shown that these factors have a significant impact on the risk of developing pulmonary embolism. So age over 60 increases the risk of developing pulmonary embolism by 24% [6]. In obesity of the II and III degree, the incidence of thrombosis in patients in the postoperative period is 65%, which is significantly higher than in patients with normal body weight [7].

There is also known a method for the clinical determination of the likelihood of pulmonary embolism in patients with sinus node weakness syndrome, corrected by a pacemaker (Patent No. 2294150, published 02.22.07) and a method for the clinical determination of the likelihood of pulmonary embolism in patients with atriventricular blockade, Patient 64 publ. 10.12.06). These methods are also based on the use of scales that summarize scores for assessing the significance of risk factors and clinical symptoms. These methods are designed to improve the accuracy and informativeness of the clinical determination of the probability of pulmonary embolism in specific categories of patients: patients with sick sinus syndrome, corrected by a pacemaker and patients with atriventricular blockade, corrected by a pacemaker. The scope of the known methods is limited, and therefore they cannot be applied to other categories of patients.

Closest to the technical nature of the proposed method is a clinical assessment of the likelihood of pulmonary thromboembolism according to the Wells scale [4]. According to the Wells scale, the following symptoms are analyzed: symptoms of deep vein thrombosis, heart rate, the presence of immobilization or surgery during the previous 4 weeks, history of deep vein thrombosis or pulmonary embolism, hemoptysis, presence of a malignant tumor, low probability of another pathology (except for pulmonary embolism ) Each symptom is assigned a specific number of points: the presence of symptoms of deep vein thrombosis - 3 points, a heart rate of more than 100 per minute - 1.5 points, the presence of immobilization or surgery within the previous 4 weeks - 1.5 points, the presence of a history of deep thrombosis veins or pulmonary embolism - 1.5 points, hemoptysis - 1 point, the presence of a malignant tumor - 1 point, the low probability of another pathology (except pulmonary embolism) - 3 points. Then the points of a particular patient are summarized. With a score of more than 6, the probability of pulmonary embolism is assessed as high, with a score of 2-6 - as average, with less than 2 points as low. This scale is quite easy to use, but has several disadvantages. Firstly, it does not take into account some important clinical manifestations, for example, tachypnea. Secondly, a low probability of another diagnosis is mentioned as a criterion. This criterion is not clear enough and serves as a source of errors of various kinds, while it is estimated by the maximum number of points, which increases the likelihood of making an erroneous decision. In addition, this method does not take into account the influence of factors such as age and the presence of excess body weight.

A new technical result is an increase in the accuracy and information content of the method and the expansion of its scope.

To solve the problem in a method for the clinical determination of the likelihood of pulmonary embolism, including the determination of clinical signs, the evaluation of each of them in points and the diagnosis by their sum, an additional consideration is given to age, body mass index (BMI) and clinical data are determined: the presence of shortness of breath, tachypnea , tachycardia, symptoms of deep vein thrombosis, also each clinical sign is evaluated in points: the presence of symptoms of deep vein thrombosis is estimated at 3 points, shortness of breath is assessed at 1 point, the presence of tachycardia estimated at 1.5 points, the presence of tachypnea is estimated at 1.5 points, after which the points of a particular patient are summed up and the value of the sum is used in calculating the values of P1 and P2 according to the formulas

P1 = -34.2 + 0.28 × age + 2.17 × BMI + 0.05 × (total score of clinical signs),

Where

age - the number of full years at the time of the survey;

BMI - body mass index calculated by the formula BMI = weight (kg) / height ² (m);

0.28; 2.17 and 0.05 - numerical values, are coefficients in the predictive model;

-34.2 - constant for patients with a low risk of developing pulmonary embolism.

P2 = -41.8 + 0.30 × age + 2.41 × BMI + 0.55 × (total score of clinical signs),

Where

age - the number of full years at the time of the survey;

BMI - body mass index calculated by the formula BMI = weight (kg) / height ² (m);

0.30; 2.41 and 0.55 - numerical values, are coefficients in the predictive model;

-41.8 - constant for patients with a low risk of developing pulmonary embolism,

and at P1> P2, a low probability of developing pulmonary embolism is determined, and at P1 <P2, a high clinical probability of pulmonary embolism is determined.

The proposed method is based on the analysis of clinical observations of 23 patients with suspected pulmonary embolism. To interpret the results, a discriminant analysis was performed using a mathematical model. Spiral computed tomographic angiopulmonography (CT angiopulmonography) was used as a method for verifying the presence of thromboembolism in the pulmonary artery basin. In 9 patients, the diagnosis of pulmonary embolism was confirmed by CT angiopulmonography, in 14 patients it was rejected. For each patient, age was established, body mass index determined by the formula BMI = weight (kg) / height ² (m) was determined, clinical data were recorded: the presence of shortness of breath, tachypnea, tachycardia, symptoms of deep vein thrombosis. Each clinical sign was assigned the following number of points: the presence of symptoms of deep vein thrombosis - 3 points, shortness of breath - 1 point, tachycardia (heart rate above 100 beats per minute) - 1.5 points, tachypnea (respiratory rate more than 20 per minute) - 1 5 points. We calculated the amount of points. Next, a discriminant analysis was performed to obtain the coefficients of a mathematical model to determine the clinical probability of pulmonary embolism. Based on the obtained coefficients and constants, formulas are proposed for determining the clinical probability of pulmonary embolism.

New is that for the implementation of the method, indexes are calculated that take into account such clinical data as: the presence of dyspnea, tachypnea, tachycardia, symptoms of deep vein thrombosis, as well as age and BMI, which, in comparison with the prototype method, excludes the consideration of such a subjective symptom as low probability of another (alternative) diagnosis. Which, ultimately, improves the accuracy of the method.

These distinguishing features are not known in the medical and patent literature. Thus, the proposed method meets the criterion of "novelty."

The combination of distinctive features does not follow explicitly for a specialist from the prior art. Thus, the proposed method meets the criterion of "inventive step".

This method has been clinically tested at the clinical base of Khakass State University. N.F. Katanova - Republican Clinical Hospital named after G.Ya. Remishevskaya. Thus, this technical solution meets the criteria of the invention "industrially applicable".

The method is as follows.

Document the patient's age.

The Ketle formula determines BMI = weight (kg) / height ² (m).

Clinical examination and collection of complaints in a patient assesses the presence of symptoms of deep vein thrombosis, shortness of breath, tachycardia, tachypnea.

Based on the data obtained, the values of P1 and P2 are calculated as follows:

P1 is calculated by the formula

P1 = -34.2 + 0.28 × age + 2.17 × BMI + 0.05 × (total score of clinical signs),

Where

age - the number of full years at the time of the survey;

BMI - body mass index calculated by the formula BMI = weight (kg) / height ² (m);

0.28; 2.17 and 0.05 - numerical values, are coefficients in the predictive model;

-34.2 - constant for patients with a low risk of developing pulmonary embolism.

P2 is calculated by the formula:

P2 = -41.8 + 0.30 × age + 2.41 × BMI + 0.55 × (total score of clinical signs),

Where

age - the number of full years at the time of the survey;

BMI - body mass index calculated by the formula BMI = weight (kg) / height ² (m);

0.30; 2.41 and 0.55 - numerical values, are coefficients in the predictive model;

-41.8 - constant for patients with a low risk of developing pulmonary embolism,

and at Р1> Р2 determine low, and at Р1 <Р2 determine the high clinical probability of pulmonary embolism.

In total, using the described method, the probability of pulmonary embolism was clinically determined in 27 patients with suspected pulmonary embolism (all patients were admitted to the radiology department with suspected pulmonary embolism) (Appendix, Table 1). Verification of the results of the study was carried out using spiral computed tomography when performing indirect angiopulmonography (CT angiopulmonography), which made it possible to visualize the presence of blood clots. Using the proposed method for assessing the clinical probability of pulmonary embolism in 20 patients, the clinical likelihood of pulmonary embolism was regarded as high, of which the pulmonary embolism was confirmed in the future (according to CT angiopulmonography) in 14 patients, and in 6 cases according to CT angiopulmonography, the diagnosis of pulmonary embolism was not confirmed . In 7 patients using the proposed method, the clinical probability of pulmonary embolism was assessed as low. In 6 out of 7 cases, the absence of thromboembolism in the pulmonary basin was confirmed by CT angiopulmonography. In 1 case, in a patient with a low clinical likelihood of pulmonary embolism, thromboembolism was diagnosed according to CT angiopulnography.

Thus, when using the new method for assessing the likelihood of developing pulmonary embolism, we got 14 true positive, 6 true negative, 6 false positive and 1 false negative result. Thus, the new method has a fairly high sensitivity (93%), with low specificity (50%) and medium accuracy (72%) in assessing the risk of developing pulmonary embolism. Comparison of the diagnostic effectiveness of our proposed method for clinical assessment of the probability of pulmonary embolism and the results of a clinical assessment of the probability of pulmonary embolism according to the Wells scale (Appendix, Table 2) showed that our method has higher diagnostic efficacy compared to the Wells scale, is characterized by high sensitivity and prognostic significance of a negative result.

Clinical examples of testing a method for clinical assessment of the probability of pulmonary embolism.

Example 1

Patient X., 28 years old, was admitted as an ambulance, admission date 10/31/11. He entered a hospital with deep vein thrombosis of the leg. Clinically established tachycardia (105 beats per minute), shortness of breath, tachypnea (BH = 22 per minute) and symptoms of deep vein thrombosis. The presence of a thrombus is confirmed by ultrasound examination of the veins of the lower leg. Overweight patient - BMI = 26.

The clinical probability of pulmonary embolism was assessed according to the proposed method, for which indicators P1 and P2 were calculated taking into account clinical data and age in accordance with the above formulas. The value of P1 corresponds to 30.41, P2 = 33.11. Since P1 <P2, a conclusion was made about the high clinical likelihood of pulmonary embolism. The patient underwent CT angiopulmonography: when performing CT angiopulmonography, a large embolus was revealed in the lumen of the left lower lobar artery.

Example 2. Patient S., 45 years old, was sent to an outpatient study to exclude pulmonary embolism. According to the clinical examination, shortness of breath, tachycardia (heart rate = 85 per minute), respiratory rate of 16 per minute, BMI = 24 were revealed.

A clinical assessment of the probability of pulmonary embolism according to the new method was carried out. The probabilities P1 and P2 were assigned to the group of patients with low and high clinical probability of pulmonary embolism, respectively. The value of P1 = 30.48, P2 = 29.54. In accordance with the new method, the clinical probability of pulmonary embolism in a patient is regarded as low. According to CT angiopulmonography, the presence of thromboemboli in the pool of the pulmonary artery is not confirmed, the diagnosis of pulmonary embolism is rejected.

Thus, the application of the proposed method will improve the diagnosis of pulmonary embolism. The positive effect of the proposed method is confirmed by the results of its use in 27 patients examined for suspected pulmonary embolism.

The proposed method has high accuracy, informativeness and sensitivity, which makes it promising for use in clinical practice.

Information sources

1. Yakovlev VB Pulmonary thromboembolism: pathophysiology, diagnosis, therapeutic tactics. / V.B. Yakovlev, M.V. Yakovleva. // Consilium medicum. - 2005. - T.7, No. 6. - S. 493-499.

2. Goldhaber S.Z. Acute pulmonary embolism: clinical outcomes in the International Cooperative Pulmonary Embolism Registry / S.Z. Goldhaber, L. Visani, M. De Rosa // Lancet / - 1999 .-- Vol. 353. Bp. 1240-1245.

3. Lilibeth A. FCCP clinical suspiction of fatal pulmonary embolism / A. Lilibeth, Pined M.D., Vasanthakumar S. et al. // Chest. - 2001. - V.120. - P.791-795.

4. Wells P.S. Derivation of simple clinical model to categorize patients probability of of pulmonary embolism increasing the models unility with the SimpliRED D-dimer / P.S. Wells, D.R. Anderson, M. Rodger et al. // Thromb. Haemost. 2000. - V.83. - P.416-420

5. Miniati M. et.al. // Amer.J.Respir. Crit. Care Med. - 2002. - V.159. - P.864.

6. Campbell I.A. Guide to the British Thoracic Society for the Management of Patients with Suspected Pulmonary Thromboembolism. / I.A. Campbell, A. Fennerty, A. Miller. // Pulmonology. - 2005. - No. 4. - S. 19-39.

7. Avdeev S.N. Thromboembolism of the pulmonary arteries / Avdeev S.N. // Pulmonology and allergology. - 2009. - No. 3. - S. 2-9.

Table 1 A patient age BMI Tachycardia points Symptoms of deep vein thrombosis, points Shortness of breath, points Tachypnea, points Total Points P1 P2 The clinical likelihood of pulmonary embolism determined by the proposed method The clinical likelihood of pulmonary embolism, according to the Wells scale Conclusion of CT angio pulmonography No. 1 51 25 0 0 one 1,5 2,5 34.46 35.13 high 1,5 Tela Number 2 28 26 1,5 3 one 1,5 7 30.41 33.11 high 9 Tela Number 3 38 24 1,5 0 one 1,5 four 28.72 29.64 high 3 no data for pulmonary embolism Number 4 21 27 0 0 one 1,5 2,5 30.40 30.95 high 4,5 Tela Number 5 73 23 0 5 0 0 3 36.30 37.18 high 3 Tela Number 6 21 34 0 0 0 0 0 45.46 46.44 high 0 Tela Number 7 54 35 1,5 3 one 1,5 7 57.22 62.60 high 4,5 Tela Number 8 81 22 0 3 one 1,5 5.5 36.50 38.55 high 7.5 Tela Number 9 63 24 1,5 3 one 1,5 7 35.87 38.79 high 4,5 Tela Number 10 65 23 1,5 3 one 0 5.5 34.19 36.16 high 4,5 Tela Number 11 55 25 0 0 0 0 0 35.45 34.95 low 2,5 no data for pulmonary embolism Number 12 82 28 0 0 0 0 0 49.52 50.28 high 1,5 Tela Number 13 63 21 0 0 one 1,5 2,5 29.14 29.09 low 0 Tela Number 14 42 24 0 3 one 1,5 5.5 29.92 31.67 high 3 Tela Number 15 75 26 0 3 one 1,5 5.5 43.50 46.39 high 3 Tela Number 16 64 29th 0 3 one 0 four 46.85 49.49 high 3 Tela Number 17 70 31 0 3 one 1,5 5.5 52.95 56.94 high 5 Tela Number 18 34 25 0 3 0 0 5 29.72 30.30 high 3 no data for pulmonary embolism Number 19 45 24 0 0 0 0 0 30.48 29.54 low 0 no data for pulmonary embolism Number 20 36 21 0 0 0 0 0 21.45 19.61 low 0 no data for pulmonary embolism

A patient age BMI Tachycardia points Symptoms of deep vein thrombosis, points Shortness of breath, points Tachypnea, points Total Points P1 P2 The clinical likelihood of pulmonary embolism determined by the proposed method The clinical likelihood of pulmonary embolism, according to the Wells scale Conclusion of CT angio pulmonography Number 21 54 21 0 0 0 0 0 26.49 25.01 low 0 no data for pulmonary embolism Number 22 58 twenty 0 3 one 0 four 25.64 26.00 high 6 no data for pulmonary embolism Number 23 68 23 0 0 0 0 0 34.75 34.03 low 0 no data for pulmonary embolism Number 24 45 28 0 3 0 0 5 39.31 40.83 high 6 no data for pulmonary embolism Number 25 34 29th 0 0 0 0 0 38.25 38.29 high 1,5 no data for pulmonary embolism Number 26 78 24 0 3 one 0 four 39.92 41.64 high 3 no data for pulmonary embolism Number 27 65 21 0 0 0 0 0 29.57 28.31 low one no data for pulmonary embolism

table 2 Indicator The results of a clinical assessment of the likelihood of pulmonary embolism using our proposed method The results of a clinical assessment of the likelihood of pulmonary embolism using the Wells scale [4] The number of true positive results fourteen 12 The number of true negative results 6 6 Number of false positives 6 5 The number of false negative results one four Sensitivity 93 75 Specificity fifty 55 Accuracy 72 65 Predictive value of a negative result 86 60 Predictive value of a positive result 70 71

Claims (1)

A method for determining the clinical likelihood of pulmonary embolism, including the determination of clinical signs, the assessment of each of them in points and the diagnosis of their sum, characterized in that they also take into account age, determine the body mass index (BMI) and clinical data: the presence of shortness of breath, tachypnea, tachycardia, symptoms of deep vein thrombosis, then, each clinical sign is evaluated in points: the presence of symptoms of deep vein thrombosis is assessed at 3 points, shortness of breath is assessed at 1 point, the presence of tachycardia is assessed at 1, 5 points, the presence of tachypnea is estimated at 1.5 points, after which the points of a particular patient are summarized and the value of the sum is used in calculating the values of P1 and P2 according to the formulas
P1 = -34.2 + 0.28 × age + 2.17 × BMI + 0.05 × (total score of clinical signs),
where age is the number of full years at the time of the survey;
BMI - body mass index calculated by the formula BMI = weight (kg) / height ² (m);
0.28; 2.17 and 0.05 - numerical values, are coefficients in the predictive model;
-34.2 - constant for patients with a low risk of developing pulmonary embolism.
P2 = -41.8 + 0.30 × age + 2.41 × BMI + 0.55 × (total score of clinical signs),
where age is the number of full years at the time of the survey;
BMI - body mass index calculated by the formula BMI = weight (kg) / height ² (m);
0.30; 2.41 and 0.55 - numerical values, are coefficients in the predictive model;
-41.8 - constant for patients with a low risk of developing pulmonary embolism,
and at P1> P2, a low probability of developing pulmonary embolism is determined, and at P1 <P2, a high probability of pulmonary embolism is determined.