Frequency of mechanical prophylaxis for deep venous thrombosis in patients admitted to an emergency room in Maceió, Brazil

ORIGINAL ARTICLE

Frequency of mechanical prophylaxis for deep venous thrombosis in patients admitted to an emergency room in Maceió, Brazil

Nathalia Leilane Berto Machado^I; Ticiana Leal e Leite^II; Guilherme Benjamin Brandão Pitta^III

^IScholarship holder, Scientific Initiation Program. Physical therapy student, Universidade Estadual de Ciências da Saúde de Alagoas (UNCISAL), Maceió, AL, Brazil.

^IIPhysical therapist, UNCISAL, Maceió, AL, Brazil. MSc. student, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, Brazil.

^IIIPhD, Associate professor, Department of Surgery, UNCISAL, Maceió, AL, Brazil. Vascular surgeon, Unidade de Emergência Armando Lages, Maceió, AL, Brazil. Hospital Escola José Carneiro, Maceió, AL, Brazil.

ABSTRACT

BACKGROUND: Deep venous thrombosis (DVT) is a multidisciplinary and frequent disease, also including complications such as pulmonary thromboembolism. Mechanical prophylaxis is one of the best (due to its low cost and proven effectiveness) and simplest means to reduce its incidence; therefore, investigating its use as an attempt to enhance benefits to the patient and hospital service is of great importance.

OBJECTIVE: To determine the frequency of mechanical prophylaxis for DVT at the Emergency Room Dr. Armando Lages in Maceió, Brazil.

METHODS: A descriptive cross-sectional study at the emergency room was carried out for an 8-month period. The sample was composed of 282 patients admitted to the nursing wards of various specialties. Data were collected from medical records and by patient interview. Each patient’s medical record was searched for use of mechanical prophylaxis for DVT, in addition to several factors for risk stratification, according to the Brazilian Society of Angiology and Vascular Surgery. Statistical analysis was performed using SPSS software and chi-square test, considering p < 0.05.

RESULTS: A total of 282 patients were analyzed, 181 (64%) men and 101 (36%) women, mean age of 54.1 years. Classification of risk was as follows: 210 (74.5%) were classified as high risk, 56 (19.8%) as moderate risk, and 16 (5.7%) as low risk. Of all patients, 234 (83%) did not received prophylaxis and 48 (17%) did. There was no statistical difference between the data obtained in the research and those found in the literature (p = 0.065).

CONCLUSIONs: Despite having its efficacy confirmed, mechanical prophylaxis for DVT has not reached satisfactory levels of use.

Keywords: Venous thrombosis, prophylaxis, thromboembolism.

RESUMO

CONTEXTO: A trombose venosa profunda (TVP) é uma doença de ocorrência multidisciplinar e freqüente, incluindo as complicações relacionadas a ela, como o tromboembolismo pulmonar (TEP). Sendo a profilaxia mecânica um dos melhores (por seu baixo custo e eficácia comprovada) e mais simples meios para reduzir sua incidência, é de grande relevância que se pesquise sua utilização visando benefícios para o paciente e o serviço hospitalar.

OBJETIVO: Determinar a freqüência da utilização da profilaxia mecânica para TVP na Unidade de Emergência Dr. Armando Lages em Maceió (AL).

MÉTODOS: Foi realizado um estudo transversal descritivo na unidade durante o período de 8 meses. A amostra foi calculada em 282 pacientes internados nas unidades de enfermarias das diversas especialidades. Os dados foram coletados em prontuários e mediante entrevista ao paciente. No prontuário de cada paciente foi pesquisada a utilização da profilaxia mecânica para TVP, além de diversos fatores para a estratificação do risco, segundo a Sociedade Brasileira de Angiologia e Cirurgia Vascular. O estudo estatístico foi realizado através do software SPSS, utilizando o teste qui-quadrado considerando o valor de p < 0,05.

RESULTADOS: Foram analisados 282 pacientes, sendo 181 (64%) homens e 101 (36%) mulheres, com idade média de 54,1 anos. Quanto ao risco, 210 (74,5%) foram classificados como alto risco, 56 (19,8%) como moderado risco e 16 (5,7%) como baixo risco. Do total de pacientes, 234 (83%) não receberam profilaxia e 48 (17%) receberam. Não houve diferença estatística entre os dados obtidos na pesquisa e os encontrados na literatura (p = 0,065).

CONCLUSÕES: Apesar de ter sua eficácia comprovada e difundida, a profilaxia mecânica para TVP ainda não atinge níveis satisfatórios de utilização.

Palavras-chave: Trombose venosa, profilaxia, tromboembolismo.

Introduction

Deep venous thrombosis (DVT) is a multidisciplinary disease characterized by total or partial formation of occlusive thrombi in deep venous system veins.¹ It is quite frequent, especially as complications of other surgical and clinical diseases. However, it can also spontaneously occur in apparently healthy people. Local clinical status is largely dependent on extension of the affected area and veins, and may be followed by systemic manifestations and complications such as pulmonary embolism.²

Development of venous thromboembolism is dependent on alteration in one or more factors of the triad described by Virchow in 1856, which considers changes in blood flow (venous stasis), blood components (hypercoagulability) and vessel wall injury (endothelial lesion) as responsible for the thrombotic process.² However, since that time stasis has been considered as the main predisposing factor to venous thrombosis. The relationship between stasis and lower limb thrombosis originated from the association between rest time and DVT incidence in clinical and anatomopathological studies. Both reduced flow velocity and volume are part of the term blood stasis and are suspected of playing a major role in the development of thrombotic process.²

DVT is the third most common cause of death of cardiovascular disease in the USA.³ It is estimated that annual incidence of diagnosed venous thromboembolism (VTE) is one to two episodes per 1,000 inhabitants in the general population. Recent data have indicated a 500,000 incidence of annual cases of VTE in the USA, with approximately 50,000 deaths due to pulmonary embolism.⁴

Because it is the main cause of thromboembolism, it is extremely important to perform DVT prophylaxis, since embolism may be the first clinical manifestation of the disease and is usually fatal in 0.2% of hospitalized patients.⁵

Although DVT prophylaxis is accepted as a well established and efficacious strategy, with detailed recommendations that should be employed in all classes of hospitalized patients,^6,7 and prevention protocols of the disease are available to all health professionals, many do not use it routinely.^8-10

Some studies have shown low adherence to prophylaxis against thrombotic events or, when performed, it was incorrectly used. However, appropriate prevention reduces DVT cases in 2/3 and PTE cases in 1/3, which increases the importance of knowing the different risk groups and their prevention methods.^2,9,11

There are two approaches to prevent thrombosis and subsequent risk of fatal pulmonary embolism: secondary prophylaxis, which corresponds to early detection and treatment of subclinical DVT with the aim of preventing a possible thromboembolism; and primary prophylaxis, which concerns use of physical and/or pharmacological methods to prevent or minimize the likelihood a patient has of developing thrombosis or pulmonary embolism.

Primary prevention is preferred in most clinical situations. It is based on the clinically silent nature of DVT in more than half of cases, on its relatively high incidence in hospitalized patients and on the occasionally severe consequences of lack of or delayed diagnosis.¹² Secondary prevention should be used in patients in whom primary prophylaxis is contraindicated or ineffective.¹³

Physical therapy prophylaxis is more commonly known as mechanical or physical, as some of its methods are not restricted to physical therapy. Such prophylaxis fights the main factor of Virchow's triad (blood stasis) using methods that increase venous reflux, in addition to being indicated to all risk stratifications and in cases of predisposition to hemorrhage by pharmacological prophylaxis.¹⁴

This study aimed at determining the frequency of mechanical prophylaxis

for DVT at an emergency room in Maceió, Brazil, with the hypothesis that it is underused according to reports in the literature.

Material and methods

This study was approved by the research ethics committee of UNCISAL, no. 657/2007, and obtained the approval of the coordination of Unidade de Emergência Dr. Armando Lages. It was conducted in agreement with resolution 196/96 of the Brazilian Health Council.

A descriptive, prospective cross-sectional study was performed with the aim of determining frequency of mechanical prophylaxis for DVT at the emergency room from December 2007 to July 2008.

Sample size was estimated in 282 patients, considering frequency of prophylaxis of 25% in a population defined as finite through a mean of number of hospitalized patients at the emergency room over the past 3 years, with 5% absolute accuracy and 5% significance level. An electronic calculator available online (http://lia.uncisal.edu.br/ensino/pdf2/CTA_Proporcao_finita.xls) was used to insert data.

Data collection was performed through analysis of medical records and interview with participants. Inclusion criteria were all patients hospitalized at nursing units of varied specialties in the emergency room during the study period. Exclusion criteria were patients aged less than 18 years and indigenous people (according to resolution 196 of the Brazilian Health Council, in culturally different communities, such as indigenous people, previous approval should be obtained from community leaders; in addition, they did not account for a relevant number in the study period).

Each patient was assessed and stratified according to DVT risk. Clinical, surgical and pharmacological factors were analyzed, following a protocol recommended by Sociedade Brasileira de Angiologia e Cirurgia Vascular (SBACV). Table 1 shows the data included in the protocol, which were collected from medical records. After the protocol was completed according to available data in each patient's medical record, the patient was interviewed (after signing an informed consent) to ensure higher reliability of risk classification. Individuals were stratified as low, medium and high risk, according to SBACV norms¹⁴ (Table 2). Patients that had reached a high risk stratum after analysis of the medical record were not interviewed, as they could not reach a higher risk stratum. Twelve patients could not be interviewed because they had a significant reduction in level of awareness and there was nobody in charge of them.

Table 1 - Click to enlarge

Table 2 - Click to enlarge

Use of mechanical prophylaxis for DVT was evaluated based on the recommendations of SBACV.¹⁴ Physical therapy is recommended for all risk strata and its prophylactic methods consist of kinesiotherapy for lower limbs,¹⁵ early walking, intermittent pneumatic compression,^16,17 lower limb elevation, use of bandage and elastic stockings, and ventilatory pattern with sustained maximum inspiration.¹⁸ A brief description of each method can be found in Table 3.

Table 3 - Click to enlarge

The statistical study was performed using the software SPSS version 15.0, in which chi-square test was used, considering p value < 0.05.

Results

A total of 282 patients were analyzed, 181 (64%) men and 101 (36%) women, mean age 54.1 years (SD = 19.42). In terms of risk stratification, 210 (74.5%) were classified as high risk, 56 (19.8%) as moderate risk and 16 (5.7%) as low risk. Of the total patients, 234 (83%) received prophylaxis and 48 (17%) did not. There was no statistically significant difference between the data obtained in the study and those found in the literature (p = 0.065).

Of 210 patients stratified as high risk, only 44 (21%) received some type of mechanical prophylaxis, while only four (7.1%) received it in the group of 56 patients stratified as moderate risk. None of the 16 patients stratified as low risk received prophylaxis (Figure 1).

The most widely used prophylaxis method was kinesiotherapy for the lower limbs in 46 patients (95.8%), followed by early walking, which was used in only two patients (4.2%), as shown in Figure 2. Other prophylactic methods were not used.

Discussion

Annual incidence of pulmonary thromboembolism (PTE) is estimated in 600,000 cases a year in the USA, 1/3 of which are fatal, and half of deaths occur in the first hour after symptom onset. Embolism is associated with thrombosis in the deep venous system of the lower limbs in 90% of cases, especially in calf veins.¹⁹

It is known that DVT can be prevented and that prevention is efficient in most cases. It is likely that reduction in mortality in the first hours of PTE is only possible through prevention, as there is no time for successful diagnostic and therapeutic measures.²⁰ However, PTE remains as a constant cause of sudden death in hospital beds.⁷

In a study performed by Marchi et al.,⁵ only 20.45% of patients received prophylaxis, and had results similar to those of other studies conducted by Engelhorn et al.⁹ and Caiafa & Bastos.²¹ In developed countries reality is a little better, but still not satisfactory, as shown by Goldhaber & Tapson²² in a study in which, of 2,726 patients diagnosed with DVT during hospital stay, only 1,147 (42%) had received prophylaxis over a 30-day period before diagnosis.

In this study, of 282 patients indicated to receive prophylaxis, only 21% high-risk and 7.1% moderate-risk patients received it. Nonprescription of mechanical prophylaxis for hospitalized patients might explain underuse of such prophylactic method, which is only performed when prescribed. It is important to stress that mechanical prophylaxis is a common method for patients with risk of bleeding that may be caused by use of anticoagulant, in addition to being an efficacious and low-cost prevention.

ENDORSE,²³ a multinational observational study, found that only half of 68,183 patients received recommended prophylactic methods (according to the American College of Chest Physicians - ACCP). Of surgical and clinical patients with risk of DVT, 10% were classified as high risk of bleeding. Underuse of prophylaxis cannot be solely explained by this reason, as these patients could have received forms of mechanical prophylaxis. However, of these patients contraindicated to anticoagulant prophylaxis, only 15% received intermittent pneumatic compression alone and 8% received graduated compression stockings as the only prophylactic method.

A possible explanation for the high number of patients at high risk of developing DVT in this study is the high demand of victims of stroke (21% of all patients) and at a lower proportion the number of victims of bone marrow trauma (6% of the total), as it is a specific group classified as high risk according to the protocol used.¹⁴ In cases of decompensated congestive heart failure (CHF), physical therapists might fear use of prophylactic methods, even when prescribed, due to increased cardiac overload. However, physical immobility, risk factor for DVT, should be avoided, and kinesiotherapy for the lower limbs may be used carefully.²⁴

Lack of knowledge of mechanical prophylaxis and of classification protocols as to DVT risk, and demand of previous pharmacological prophylaxis for medium- and high-risk patients (according to the protocol used)¹⁴ can be other reasons for the lack of routine use of such prophylaxis. To change this reality it is extremely important to implement educational strategies with the aim of warning practitioners to the importance of prophylaxis of DVT and to the severity and prevalence of thromboembolism.

Some studies have been conducted with such goals. Anderson et al.²⁵ reported increased use of prophylaxis from 29 to 52% in hospitalized patients with important risk for development of venous thrombosis after introduction of educational strategies; knowledge of statistical data on thromboembolic disease at the hospital where practitioners worked was an important factor in their adherence to prophylaxis.

Maffei et al.²⁶ observed the effect of implementing a guideline for venous thromboembolism prophylaxis at a private hospital, including physicians, nurses and physical therapists; although it increased concern over prophylaxis, it had little increase on quality and time of use; therefore, other more active and continued interventions were necessary.

Conclusion

Based on the data presented above, the authors conclude that, although the efficacy of mechanical prophylaxis for DVT has been confirmed and reported by many studies, it is still underused in hospital routine, considering that it was only applied to a small number of patients with potential risk of DVT.

Such data confirm the need of implementing strategies of continued education so that practitioners know how to prevent DVT and its complications when prophylaxis is prescribed. It is crucial to have the entire multidisciplinary team aware of the benefits of such prophylaxis to know when to indicate and prescribe it, aiming at a better quality of life for the patient and a more advantageous cost-effectiveness for the hospital service.

References

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Correspondence

Publication Dates

• Publication in this collection
  20 Feb 2009
• Date of issue
  Dec 2008

History

• Accepted
  25 Sept 2008
• Received
  24 Aug 2008