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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 20  |  Issue : 1  |  Page : 60-66

Postoperative pulmonary embolism, risk factors, and medical thromboprophylaxis: a 2-year retrospective study


1 Department of Chest Diseases, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt
2 Department of Vascular Surgery, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt
3 Department of Community and Occupational Medicine, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt
4 Department of Radiodiagnosis, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt
5 Department of Internal Medicine, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt

Date of Submission04-Jun-2021
Date of Decision12-Aug-2021
Date of Acceptance23-Aug-2022
Date of Web Publication4-Mar-2022

Correspondence Address:
MD Eman Sobh
Department of Chest Diseases, Faculty of Medicine for Girls, Al-Azhar University, 11754 Nasr City, Cairo
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/azmj.azmj_67_21

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  Abstract 


Background and aim The major surgical procedures have a significant risk of venous thromboembolism (VTE), especially pulmonary embolism (PE), leading to poor prognosis and life-threatening conditions. The major surgical procedure has 20-fold risk increase in VTE and the risk is increased by 30% in the absence of optimal prophylaxis. This study aimed to estimate the incidence of PE among surgical patients undergoing preoperative thromboprophylaxis according to Caprini score, these considerations can improve the clinical outcome and allow optimal use of thromboprophylactic strategies against VTE.
Patients and methods We performed retrospective analysis of records of patients admitted to surgical wards at our hospital and identified those who developed postoperative PE. We calculated Caprini score to assess the risk for VTE.
Results Among patients admitted to surgical wards, we identified 107 cases of postoperative PE. Most of them had major surgeries, most of them were females, and a considerable proportion of those who developed PE did not receive thromboprophylaxis although being at moderate or high risk for VTE according to Caprini score. Few patients had poor outcome.
Conclusion Perioperative thromboprophylaxis is crucial to avoid complication with VTE. Caprini score may be a good clinical score to decide which patients to receive perioperative thromboprophylaxis.

Keywords: Caprini score, pulmonary embolism, thromboprophylaxis, venous thromboembolism


How to cite this article:
Sobh E, Abdel Wahab MA, Adawy ZR, Abdelgalil HM, Saleh OI, Zakaria DM, Elshahat RS. Postoperative pulmonary embolism, risk factors, and medical thromboprophylaxis: a 2-year retrospective study. Al-Azhar Assiut Med J 2022;20:60-6

How to cite this URL:
Sobh E, Abdel Wahab MA, Adawy ZR, Abdelgalil HM, Saleh OI, Zakaria DM, Elshahat RS. Postoperative pulmonary embolism, risk factors, and medical thromboprophylaxis: a 2-year retrospective study. Al-Azhar Assiut Med J [serial online] 2022 [cited 2022 Jun 29];20:60-6. Available from: http://www.azmj.eg.net/text.asp?2022/20/1/60/339076




  Introduction Top


Venous thromboembolism (VTE) is a condition involving both deep venous thrombosis (DVT) and pulmonary embolism (PE) [1]. Perioperative (VTE) is a leading cause of morbidity and mortality among surgical patients, which can be preventable [2]. The exact incidence of VTE is uncertain. It was reported to be high up to 25% in hospital surgical patients, 30% of them are complicated [3]. In addition, postoperative surgical PE carries a major economic burden due to increased hospitalization period, medications, and care [4]. Surgery is a major risk factor for PE [5]. Increased risk of VTE following surgery is mainly due to hypercoagulability, endothelial injury, and stasis (Virchow’s triad) [6]. Surgical procedures are associated with systemic inflammation resulting in increased levels of inflammatory mediators and procoagulant microparticles and thrombi. Of these mediators, interleukin-6, interleukin-8, and tumor necrosis factor-alpha are commonly reported to be elevated [7]. Other surgery-related risk factors include immobilization, infection, dehydration, and type and duration of surgical procedure [8]. Risk of PE is higher after vascular, orthopedic, and gynecologic surgeries, respectively. The risk of PE is increased after surgery is high during the first 6 weeks, but the risk extends beyond 6 weeks [9]. Some studies reported VTE in asymptomatic patients postoperative [10]. Comorbidities are contributing risk factors for development of VTE, including trauma, congestive heart failure, malignancy, neurologic disease, and paralysis of extremities [5]. Although bariatric surgery was reported to be associated with high-risk PE, some studies found that the incidence is very low [10],[11].

Prevention and early detection of VTE are crucial to prevent postoperative VTE-related morbidity and mortality [12].

Risk assessment is essential, weighing the risk of thrombosis and risk of bleeding for every patient and proper choice of the suitable prophylactic method is mandatory. No VTE tool is perfect [13]. Some guidelines recommend the use of Caprini score risk-assessment tool [14]. Also, no uniform protocol for VTE prophylaxis (indication, type, dose, and duration of anticoagulant) is approved worldwide. Also, no uniform method of detection of DVT or PE, so the incidence is highly variable [6].

In Egypt, however, to the best of our knowledge, the risk of postoperative PE may have been underestimated. No uniform risk-assessment tools or thromboprophylaxis protocol is used. Efficient risk assessment will enable proper and cost-effective use of thromboprophylaxis in surgical patients and decrease morbidity and mortality. Hence, this study was conducted to investigate the incidence, risk factors, and clinical practice of preoperative thromboprophylaxis in our hospital.


  Patients and methods Top


Ethics approval and consent to participate

Ethical approval was obtained from the research ethics committee of Faculty of Medicine for Girls, Al-Azhar University (AFMG-IRB No. 202101595). The study is conducted in accordance with Helsinki standards as revised in 2013. Informed consent is not required as the study is retrospective. Data were collected anonymously and kept confidential.

Study design

This study is a retrospective nested-cohort study (cross-sectional cohort study) [15] conducted at Al-Zahraa University Hospital Cairo, Egypt, which is a tertiary-referral university hospital.

Sampling method and sample size

We used convenience-sampling technique. Sample size is a census sample, we included all cases with PE during the study period, so sample-size calculation was not required.

Study participants

Among 10 182 patients admitted to surgical wards (general surgery, orthopedic surgery, vascular surgery, and obstetrics/gynecology surgery departments), and had major surgery (elective or emergency) under general or regional anesthesia; we identified 107 patients who developed in-hospital PE between January 2018 and December 2019.

Inclusion criteria

We included patients who satisfied the following criteria: (a) over 18 years old, (b) hospitalizations not related to VTE treatment, and (c) hospital stay exceeding 2 days.

Exclusion criteria

All cases who were diagnosed as having DVT at the time of admission, those who were receiving anticoagulant or antiplatelet drugs for any reason, those in whom anticoagulation therapy was contraindicated for any reason, and those who had been admitted for lower-limb vascular interventions.

Data recorded included demographic and clinical data, such as name, sex, age, height, weight, hospitalization date, type of surgery, hospital-stay duration, PE risk factors, if the patient received venous VTE prophylaxis prior to surgery according to surgeon’s decision and local practice, type, dose, and duration of VTE prophylaxis, investigations performed, and outcome.

All patients underwent complete clinical examination by pulmonologist, vascular surgeon, and internist. Investigations performed included laboratory investigations, ECG, plain chest radiography, venous duplex ultrasound on both lower limbs for assessment of DVT, and computed tomography pulmonary angiography for confirmation of PE ([Figure 1]). The results of imaging were interpreted by a radiologist in collaboration with clinicians.
Figure 1 Computed tomography pulmonary angiography (CTPA) of one of the studied cases. CTPA axial scans show that central filling defects are seen in both the main left and right PA and their branches (long arrows), also, there is filling defect in the pulmonary trunk (wide arrow) denoting massive PE. PE, pulmonary embolism.

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Patients were managed according to the guidelines for management of PE.

Patients were categorized into those who received prophylaxis (n=58) and those not (n=49).

The concept of thromboprophylaxis administration perioperative is not uniform among different surgical departments, so we calculated Caprini score for each case according to the data present to evaluate clinical practice regarding the need for thromboprophylaxis.

Statistical analysis

Data collected were reviewed, coded, and statistically analyzed using Statistical Package for the Social Science (SPSS) program, version 16 (SPSS Inc., Chicago, Illinois, USA). Data were described in terms of mean±SD and percentage. The χ2 test was used for the comparison of qualitative data and the Student’s independent t test for quantitative data. Significance level was taken at P value less than or equal to 0.05.


  Results Top


Among 10 182 patients admitted to our hospital surgical wards (vascular, orthopedic, cardiothoracic, obstetrics and gynecology, and general surgery departments) during the study period, we detected 107 consecutive patients who developed postoperative PE. The incidence was 1%. The mean age of the studied group was 37.3±9.5, most of them were females [74 (69.2%)]. Only 58 (54.2%) of patients with PE received medical prophylaxis for VTE before surgery and 49 (45.8%) did not receive ([Table 1], [Table 2]).
Table 1 Demographic data of patients with pulmonary embolism

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Table 2 Clinical data, and laboratory investigations of patients with pulmonary embolism

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There was a significant difference between patients who received thromboprophylaxis and those who did not. Those who did not receive prophylaxis were younger, lower BMI, smokers, had previous PE, and low Caprini score (1.8±0.8) ([Table 2]).

Most of the studied patients had vascular, obstetric/gynecologic, and orthopedic surgeries (47.7, 23.4, 15.9%, respectively). Notably, all patients who underwent cardiothoracic, mastectomy, orthopedic, and bariatric surgeries received thromboprophylaxis. Patients with vascular and obstetric/gynecologic were detected more (65.3, 34.7%, respectively) among those who did not receive prophylaxis versus (32.8, 13.8%) among those who received ([Figure 2]).
Figure 2 Percentages of pulmonary embolism in patients according to surgery type and preoperative thromboprophylaxis. Most of the studied patients had vascular, obstetric/gynecologic, and orthopedic surgeries. Notably all patients who underwent cardiothoracic, mastectomy, orthopedic, and bariatric surgeries received thromboprophylaxis. Patients with vascular and obstetric/gynecologic were detected more among those who did not receive prophylaxis.

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Caprini score showed that all patients with the highest risk of VTE received thromboprophylaxis. A considerable percentage of patients at moderate or high risk of VTE did not receive thromboprophylaxis, while a small percentage of those who received thromboprophylaxis were at low risk ([Figure 3]).
Figure 3 Capirni score for assessment of VTE risk in the studied population. Using Caprini score for VTE-risk assessment: all patients at the highest risk of VTE received thromboprophylaxis. Nearly more than half of the patients who did not receive prophylaxis (59.2%) lie in moderate or high risk (38.8%) and high risk (20.4%) of developing VTE (38.8 and 20.4%, respectively). VTE, venous thromboembolism.

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  Discussion Top


In this study, the incidence rate of PE in surgical patients at our hospital was 0.8% (107 patients out of 10 182). Smoking was found in nearly half of the cases, the other risk factors included chronic obstructive pulmonary disease, previous PE, dyslipidemia, hypertension, and diabetes ([Table 1], [Table 2]). Surgery is a major risk factor for PE (relative risk 5–20) [16]. The incidence rate found in our study was comparable to that reported in previous studies. Balachandran et al. [17] reported incidence rate 1.1% in patients who underwent emergency abdominal surgeries during hospitalization. Kuttanchettiyar and Chisthi [18] reported the incidence rate of DVT to be 1.19% in the postoperative period after major abdominal surgeries in India. Another study in Canada found that the cumulative incidence of VTE after major abdominopelvic oncologic surgeries was 3.01 and 1.6% during hospitalization [19]. Similar results were reported in Martino et al. [20] study who found an overall incidence of postoperative PE 1.7%. The high cumulative incidence reported in Alsubaie et al. [19] study could be related to the fact that they reported patients who developed VTE up to 90 days after surgery.

Anderson [21] reported that risk factors for VTE were age above 40, obesity, history of VTE, cancer, and major surgery.

In our study, only 58 (54.2%) of patients with PE received medical prophylaxis for VTE before surgery and 49 (45.8%) did not receive ([Table 1]). Thromboprophylaxis was made according to clinicians’ judgment. Patients who did not receive thromboprophylaxis were younger, lower BMI, smokers, had previous PE, and had low Caprini score ([Table 1] and [Table 2]). Most of the studied patients had vascular, obstetrics/gynecologic, and orthopedic surgeries (47.7, 23.4, and 15.9%, respectively). Notably all patients who underwent cardiothoracic, mastectomy, orthopedic, and bariatric surgeries received thromboprophylaxis. Patients with vascular and obstetric/gynecologic were detected more (65.3, 34.7%, respectively) among those who did not receive prophylaxis versus (32.8, 13.8%) among those who received ([Figure 2]). Major general surgery had an odds ratio more than 10, while orthopedic surgery and previous VTE had an odds ratio 2–9, laparoscopic surgery, and obesity had an odds ratio less than 2 [21]. Prophylaxis for VTE is recommended for those undergoing major surgeries, as well as those with multiple risk factors. Those with one of the weak or moderate risk factors do not require VTE prophylaxis [21].

Cochrane review reported that prolonged thromboprophylaxis for abdominal and pelvic surgeries reduced the risk of VTE compared with prophylaxis during hospitalization [22].

In our work, Caprini score showed that all patients with the highest risk of VTE received thromboprophylaxis. A considerable percentage of patients at moderate or high risk of VTE did not receive thromboprophylaxis, while a small percentage of those who received thromboprophylaxis were at low risk ([Figure 3]).

In our study, young and middle age (<50 years) was identified to be a risk factor for PE, specially with those who did not receive prophylaxis where LMWH is highly recommended for young patients before major surgery (explanation by type of surgery and risk factors).The mean age of the studied patients was 37.3±9.5, most (69.2%) of them were females. The highest risks detected were smoking (46.7%), BMI more than 25 (35.5%), chronic respiratory disease (chronic obstructive pulmonary disease) 34.6%, asthma cardiac causes (26.1%), and history of PE 10.3%.

Patients with cancer had a 14-fold of developing postoperative PE compared to those with benign etiology. Ovarian cancer had the highest risk of postoperative PE (6.8%) [20].

In the current study, the orthopedic surgery represented 15.9% of PE cases although all of them received thromboprophylaxis. Orthopedic surgery patients are at increased risk of VTE due to immobility before and after surgery, positioning, and during surgery, which adds to venous stasis [23].

The cumulative incidence of postoperative PE after major orthopedic surgery was 1.99%. Most of them developed DVT within 72 h after surgery, despite thromboprophylaxis. Femur fracture, old age, and bedridden were the highest risk factors [24].

The strengths of this study include the cohort and the large size of the study. This study has some limitations, including the single center and the short period follow-up.


  Conclusions Top


Surgery is a risk factor for PE, despite the use of thromboprophylaxis. Vascular surgeries carry the highest risk of VTE. Using Caprini score detected some cases who are at increased risk of PE.

Recommendations

All surgical patients should be evaluated for risk of VTE prior to surgery. Caprini score should be included in clinical evaluation of surgical patients to detect those at risk of VTE. Administration of perioperative anticoagulation according to Caprini score category or any other clinical score and not on clinician’s sense.

Acknowledgements

The authors intend to publish a research article entitled ‘Postoperative pulmonary embolism; risk factors and medical thromboprophylaxis 2-year retrospective study’ in the esteemed journal ‘Al-Azhar Assiut Medical Journal’. This article highlights the importance of using venous thromboembolism risk clinical scores in patients undergoing surgery. In this work, we found 107 patients who developed pulmonary embolism during hospitalization period after surgery. Venous thromboembolism (VTE) risk assessment is very important to be justified as a considerable percentage of our patients who did not receive thromboprophylaxis were indicated when we calculated Caprini score. Vascular and obstetrics/gynecology surgeries carried the highest VTE risk. Our results confirm the need for local policy for VTE-risk assessment and administration of thromboprophylaxis.

Authors’ contributions: all authors participated in study design, concept, data analysis, interpretation, review of literature, and participated in writing. H.M.A. performed statistical analysis. M.A.A.W. performed data collection and obtained approvals. E.S. drafted the paper and performed critical revision. All authors have read and agreed for the final version to be published.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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