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Year : 2012  |  Volume : 23  |  Issue : 4  |  Page : 519-523
Deep venous thrombosis prophylaxis in oral and maxillofacial surgery: A Brazilian survey

1 Surgery Department, Faculty of Medical Sciences State, University of Campinas, UNICAMP, Brazil
2 Diagnostic and Surgery Department, Dental School of Araraquara, UNESP, Brazil

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Date of Web Publication20-Dec-2012


Background : Deep venous thrombosis (DVP) is a frequent disease. Prophylaxis is the best means to reduce its incidence, for lowering morbidity and mortality rates and treatment costs caused by its complications.
Objective : To evaluate the knowledge and use of any kind of DVT prophylaxis by Brazilian Oral and Maxillofacial surgeons.
Materials and Methods : A questionnaire was sent to all Oral and Maxillofacial surgeons associated to the Brazilian College of Oral and Maxillofacial Surgeons that have a valid e-mail address. The data retrieved was evaluated and tabulated.
Results : Of the 1100 questionnaires sent, only 4% were retrieved. The 42 retrieved were included in the study. Twenty six of the surgeons do not use any kind of deep venous thrombosis (DVT) prophylaxis, 11 use mechanical means as elastic compressive stockings or pneumatic compressive devices for prophylaxis, and 5 uses low-molecular weight heparins (LMWH) as the choice for prophylaxis.
Conclusion : The data collected, despite the low rate of participation (4%) by the surgeons, shows that this subject still does not receive proper attention. Whereas other medical specialties make routine use of prophylactic means maybe the maxillofacial surgeons lack concern on that matter.

Keywords: Deep vein thrombosis, embolism, maxillofacial surgery

How to cite this article:
Monnazzi MS, Passeri LA, Gabrielli MF, Hochuli-Vieira E, Gabrielli MA, Pereira Filho V A. Deep venous thrombosis prophylaxis in oral and maxillofacial surgery: A Brazilian survey. Indian J Dent Res 2012;23:519-23

How to cite this URL:
Monnazzi MS, Passeri LA, Gabrielli MF, Hochuli-Vieira E, Gabrielli MA, Pereira Filho V A. Deep venous thrombosis prophylaxis in oral and maxillofacial surgery: A Brazilian survey. Indian J Dent Res [serial online] 2012 [cited 2023 Jun 1];23:519-23. Available from:
Deep venous thrombosis (DVT) development depends on the alteration of one or more factors of the triad described by Virchow that considers the blood flow alterations, hemostasis and vascular wall as responsible for the emergence of DVT. After 150 years his statement remains true and the knowledge of relative function of any one of those factors made possible the comprehension of the thrombotic phenomenon, making easier the diagnosis and identification of the risk patients and helping in their management. [1] DVT is a frequent disease arising mainly as surgical and clinical complications of other diseases. However, it can occur spontaneously in healthy people. [2],[3]

It is known that DVT could lead to critical complications, such as pulmonary embolism (PE) and or post-thrombosis syndrome. [4] Nearly 10% of the symptomatic pulmonary embolism leads to death in one hour after its starts, and if not treated, about 30% of the early treated patients with non-lethal pulmonary embolism would die. [5],[6] The venous thromboembolism is mentioned as the major morbidity cause among hospitalized patients at the United States [6],[7] and the PE could be the more common cause of avoidable mortality inside hospitals. [8]

Low-molecular weight heparins (LMWH) such as enoxaparin were the first-line agents recommended for the treatment and/or prophylaxis of thromboembolic alterations by the American College of Chest Physicians. [9] In Europe the LMWH has replaced warfarin as the standard of DVT prophylaxis after orthopedic procedures. [9] In spite of the hospital΄s implementation of protocols for DVT prophylaxis be a major concern, the use of antithrombotic drugs is subject to a variety of hemorrhagic complications, such as orbital hemorrhagic complications in patients who had midfacial fractures and were receiving enoxaparin therapy presented in a study by Jamal et al.[10] or either a femoral nerve palsy after mandibular reconstruction with microvascular iliac flap described by Toro et al.[11]

Regarding orthognathic operations, the venous thrombosis after this kind of surgery is believed to be uncommon, but there are a few published data to quantify the incidence after oral and maxillofacial operations. The incidence was estimated by Lowry [12] as 0,00035% based on the recall of 103 consultant maxillofacial surgeons in the previous 5 years. Other authors like Van de Perre [13] reported 3 episodes of DVT resulting in 1 case of pulmonary embolism among 2049 patients undergoing orthognatic operations. However, only the complications occurring in the first 48 hours postoperatively were included in the study. Moreano et al.[14] identified 34 postoperative thromboembolic events after 12.805 otolaryngology and head and neck operations and reported that the incidence of DVT or PE was 0,1% after general otolaryngology operations and 0,6% after head and neck surgery.

The THRIFT Consensus Group [15] recommended that all medical and surgical patients admitted to hospital should be assessed for risk factors [Table 1] [16] and that they should receive proper prophylaxis related to the risk. The choice between mechanical or antithrombotic methods should depend on the balance of the risks of thromboembolism against bleeding in the individual patient.
Table 1: Surgical patient risk groups at risk for developing DVT

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   Materials and Methods Top

Attempting to access the knowledge on the specific field and determine if and which is the DVT and PE prophylaxis methods of choice by the Brazilian oral and maxillofacial surgeons, a questionnaire was elaborated [Table 2] and it was send by electronic mail to all members of the Brazilian College of Oral and Maxillofacial Surgery.
Table 2: DVT prophylaxis in oral and maxillofacial surgery

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All members that possessed an e-mail address on the College΄s records were invited to answer 6 questions regarding this subject. No identification was required. The questions were basically yes or no answers and a few fields in blank were left for those who feel like to write some details. The members vary from senior doctors to former residents, so the category of the member was also asked at the questionnaire. About one thousand members were included in the research.

The answers were sent by e-mail also for the Brazilian College secretary and after that they were redirected to the responsible author΄s e-mail. The data collected were evaluated and tabulated.

   Results Top

The secretary of the Brazilian College sent 1100 questionnaires with the invitation to answer it and a brief letter specifying that the ones interested in answer the form had one month to do so, identification not being necessary. Only four percent (4%) of all the questionnaires sent were replied (42 questionnaires), which were included in the study.

After analysis and tabulation of the data retrieved we could find the following information on the studied samples. Of all 42 surgeons that answered to the questionnaire, 26 (62%) do not routinely use any kind of drug therapy for the DVT prophylaxis, or any mechanical means, 5 (12%) do use LMWH, and 11 (26%) use only mechanical means [Graph 1]. Of this 5 surgeons that do use drug therapy, 3 use 40 mg of LMWH by subcutaneous injection 1 hour prior to the surgery as the unique dose; one uses this same drug and this same dosage but with one subcutaneous injection 12 hours preoperatively and another injection within 24 hours postoperatively; and one surgeon uses 20 mg of this same drug once a day for the duration of hospitalization. Of the 37 surgeons that do not use LMWH as prophylactic measure, 11 use mechanical means for the DVT and PE prophylaxis, and one surgeon use LMWH and compressive stockings Thus, seven (7) use elastic compressive stockings during surgery and the hospitalization period, four (4) use pneumatic compressive leg devices during the surgery time and one (1) use pneumatic compressive leg device during the surgery and elastic compressive stockings at the remaining hospitalization period.

The 26 surgeons that do not use any kind of prophylactic means answered that the reason for this conduct is the following tradition of the service where they received oral and maxillofacial training (18 surgeons) and because they do not see justification at the scientific specific literature to use prophylaxis (8 surgeons).

When asked in which situation they would consider the use of LMWH as prophylactic means, the surgeons informed that they would do so in orthognatic surgeries (1 surgeon); in orthognatic and severe trauma patients and in all surgeries that last more than three hours (1 surgeon); in orthognatic surgery and in all surgeries that last more than 3 hours (4 surgeons); in all risk patients and in orthognatic surgery (1 surgeon); in all surgeries that last more than 3 hours (9 surgeons); in all risk patients (15 surgeons); in severe trauma patients and in risk patients (1 surgeon) and several did not answer that question (10 surgeons).

Of all questionnaires included in this study, 26 of them were answered by professionals that had more than 6 years of practice, 10 had between 2 and 5 years of practice; 32 work in public hospitals and 18 in private hospitals, some of them work at the two types of hospitals; 11 of them are university professors.

   Discussion Top

Current maxillofacial scientific literature provides no uniform protocol on the use of LMWH in patients who undergo maxillofacial surgical procedures neither in those who have facial fractures. Probably due to the low incidence of DVT as a complication of maxillofacial surgery, which ranges from 0,00035% to 0,06%, [10],[17] some authors recommend using the 40 mg once daily dosing, or, if the anticoagulation prophylaxis is contraindicated for any reason or it the patient can be early mobilized, he should receive mechanical methods for prophylaxis such as intermittent pneumatic compression. Those procedures show to decrease the risk of DVT, although they are less efficacious than LMWH therapy. [10],[17] However, other studies show a higher incidence of DVT complications after orthognathic operations. Blackburn et al.[18] evaluated 256 patients and 2 of them presented symptomatic DVT postoperatively (1,6%), confirmed by venography.

Orbital hemorrhage has been reported as a complication of the LMWH therapy use in patients with orbital or zygomatic complex fractures, and the retrobulbar hemorrhage is a sight-threatening emergency, because the orbital walls and septum form a 3-dimensional boundary, and the bleeding into this closed space may result in optic nerve compression, globe ischemia and high intraocular pressure. [10],[12],[19] Jamal et al.[10] recommend a full initial ophthalmologic examination in all patients with orbital and zygomatic fractures, and prompt reevaluation after an episode of emesis that could result in a sudden rise blood pressure, which may lead to the rupture of small orbital blood vessels. In the authors opinion if a high risk DVT patient had a facial fracture the 40 mg once daily dosage of LMWH rather than the twice daily dosing is advised. Also, if possible, dosing should be stopped 12 hours preoperatively and delayed 10 to 12 hours postoperatively, because a study examining the incidence of postoperative orbital hemorrhage after eyelid surgery found the greatest incidence to occur within the first 3 hours after the surgical procedure. [20]

According to Blackburn et al., [18] nowadays it would be unethical to perform a study for oral and maxillofacial operations without any thromboprophylactic measures, reason that make more difficult the evaluation of the real necessity of LMWH therapy for those patients. One of the reasons that make this kind of research unethical are studies like the meta-analysis made by Clagett et al., [21] that showed a 25% incidence of postoperative DVT after major operations (>30 minutes) in the absence of any prophylactic measure.

The use of graduated compression stockings during the general major surgery reduced the incidence of DVT from 24,5% to 9.3% according to Clagett et al.[21] Comerota et al., [22],[23] showed that veins in the upper limb become distended during operations and this may cause vascular endothelial injury. Adding the loss of muscular tone and venous pump function, use of neuromuscular blocking agents, prolonged anesthesia with the venous distension they are factors that contribute to blood stagnation in the limb veins. Intermittent pneumatic compression during operations may reduce the incidence of DVT after major surgery from 9,9 to 25,1%. [21]

The pharmacological prophylaxis results in significant reduction in the incidence of venous thromboembolism. LMWH is presently generally preferred to unfractionated heparin because it is at least as effective and safe, can be given once daily and does not need to be monitored. [24] LMWH is also less like to cause thrombocytopenia and osteoporosis than unfractionated heparin. One disadvantage of LMWH in that protamine sulphate is less effective as an antidote.

The bleeding risk is a clinical concern in orthognathic patients, but there are no data available to quantify the risk. Placebo-controlled trials suggest that LMWH carries no additional risk of major perioperative bleeding after hip replacement. [24] Recommended thromboprophylaxis in surgery state that "according to level of risk, the most appropriate form of prophylaxis can be selected according to local recommendations" according to the THRiFT II guidelines [25] [Table 3]. Low-risk patients have a risk of developing DVT of 1% or less, moderate-risk patients have a 10 to 40% risk of developing DVT and the high-risk group of patients has a 40 to 80% risk of developing it. [16]
Table 3: Prophylaxis for DVT according to the level risk

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We agree with Prandoni [26] who states that despite the existence of comprehensive consensus guidelines for the prevention and treatment of DVT, the thromboprophylaxis remains underused, which corroborate with our results of surgeons that do use any kind of prophylaxis. Reasons for underuse include underestimation of the risks, lack of awareness by the forming centers of oral and maxillofacial surgeons, and concerns about the risk of bleeding what seems to be unlikely at least theoretically.

In the case of Brazil it is also true that intermittent compression devices, which would be the method of choice for most orthognathic surgery patients, are not available in many hospitals. Also, the abundant vascularization, difficult access to a bleeding deep bone vessel and the airway risk by hematoma formation in the head and neck area creates a doubt about routine use of LMWH in Oral and Maxillofacial Surgery unless systemic conditions or trauma warrant it.

In maxillofacial surgery the incidence of DVT and PE is low probably due to a relatively high proportion of young healthy patients treated in this discipline and the early mobilization in most cases. Nevertheless with advances in the specialty the risk factors of the maxillofacial surgery patients are increasing with the number of older and medically compromised patients and there can be no justification to withhold prophylaxis when indicated, whether pharmacological or mechanical. Further studies on this field are required; however the patients should not be exposed to DVT risk in spite the low incidence. Risk classification should be assessed prior to surgical procedures and proper prophylaxis used when indicated. Teaching programs should provide the necessary information and training on the matter for their residents.

   References Top

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Correspondence Address:
Marcelo S Monnazzi
Surgery Department, Faculty of Medical Sciences State, University of Campinas, UNICAMP
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.104963

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