EARLY RECOGNITION OF POSTOPERATIVE PULMONARY THROMBOEMBOLISM AFTER ELECTIVE HIP REPLACEMENT SURGERY – A CASE REPORT RANO PREPOZNAVANJE POSTOPERATIVNOG NASTANKA PLUĆNE TROMBOEMBOLIJE NAKON ELEKTIVNE

-SummaryIntroduction. Surgical patients have an increased risk of de veloping pulmonary thromboembolism. Early diagnosis is dif ficult due to the presence of non-specific symptoms. Case Report. A case of a 72-year-old man admitted to the Intensive Care Unit after elective orthopedic hip replacement surgery is presented, due to a sudden worsening of the general condition accompanied by tachypnea, decreased oxygen saturation, neck cyanosis, hemodynamic instability, and heart rhythm disorders. Pulmonary thromboembolism was confirmed by computed tomography and echocardiography. Conclusion. The symptoms of pulmonary thromboembolism are usually nonspecific. Early recognition with confirmation by diagnostic procedures is im portant in order to reduce the mortality rate .


Introduction
Pulmonary thromboembolism (PTE) is an obstruction of one or more branches of the pulmonary artery with thrombi originating from the venous system [1]. Patients with trauma, fractures of the long bones of lower extremities, patients after orthopedic, major abdominal, gynecological, oncology, chest, and cardiovascular surgeries are at increased risk of developing PTE [2].

Case Report
A72-year-old man was admitted to the General Hospital Vrbas for elective hip replacement surgery. Fifteen minutes after the surgery, performed in spinal anesthesia, in the post-anesthesia unit the patient presented with a sudden worsening of the general condition accompanied by tachypnea, decreased oxygen saturation, and neck cyanosis. Noninvasive monitoring revealed a hemodynamic instability followed by hypotension with periodic cardiac ar-rhythmia manifesting with ventricular extrasystoles. The intravascular volume compensation was done using vasoactive and antiarrhythmic drugs, but without the expected therapeutic response, so the patient was transferred to the Intensive Care Unit. After transfer to the Intensive Care Unit, the patient breathed spontaneously; a control chest Xray and arterial blood gas analysis were performed, with satisfactory results. Even though oxygen therapy was used, a reduced oxygen saturation (77%) and cardiac rhythm disturbances, ventricular and supraventricular extrasystoles, persisted. All laboratory tests were performed and a significant increase of D-dimer (17,265) was observed. Contrast-enhanced computed tomography (CT) of the chest and echocardiography (EHO) were performed. The CT and EHO findings confirmed pulmonary thromboembolism ( Figure 1A and 1B). After the diagnostic examinations, heparin was included in the therapeutic regimen, first in a bolus of 8000 international units, then in a continuous infusion of 42 milliliters per hour. After the check-up of coagula-Gojković M, et al. Pulmonary Thromboembolism after Hip Replacement Surgery tion parameters every 3 to 4 hours, the heparin infusion rate was corrected and it was discontinued after 12 hours. On the first postoperative day, after stabilization of the general condition, the patient was transferred to the Institute of Pulmonary Diseases of Vojvodina in Sremska Kamenica for surgical treatment.
Pulmonary thrombectomy was performed successfully and 15 days after surgery the patient was discharged in a satisfactory general condition.

Discussion
The incidence of pulmonary thromboembolism after orthopedic surgical procedures is estimated to be 0.7-30% and 4.3% to 24% after hip fracture surgery [3]. Risk factors for venous thromboembolism are associated with comorbidities, perioperative course specificities, including acute inflammatory reaction caused by tissue trauma, coagulation cascade activation, immobilization and venous pathways. Males are at increased risk of PTE [4]. In most cases the symptomatology is nonspecific; symptoms in conscious patients may help establishing the diagnosis of PTE, while they are masked with the anaesthetized, mechanically ventilated patients.
The most common nonspecific symptoms are tachycardia and hypotension. Severe heart rhythm disorders are rare [4]. Atrial fibrillation/flutter, first, second and third degree blocks, as well as ventricular heart rhythm disorders, are present in less than 5-10% of cases [4,5]. In patients who breathe spontaneously, the nonspecific indicators of inadequate gas exchange are hypoxemia, respiratory alkalosis and hypocapnia. D-dimer is a sensitive, but not a specific test; it may be positive in conditions unrelated to pulmonary embolism such as infection, malignancies, and trauma. Our patient presented with a significant increase in D-dimer, with initially satisfactory parameters of arterial gas analysis. A negative result is useful for excluding the diagnosis with low risk patients; however, it is of no benefit in establishing the diagnosis and estimating its severity. Chest radiography is not of great importance for diagnosis [6]. The presented patient had a satisfactory chest X-ray. The PTE was confirmed by CT and EHO.
According to Kearon, many patients may have a silent and clinically unrecognized PTE. As a proof, he states that not a single patient died of pulmonary embolism if he received anticoagulants, whereas 26% died since they did not receive anticoagulants [7]. In fact, 50% of surgical patients who develop pulmonary thromboembolism receive a perioperative thromboembolic prophylaxis [3]. Our patient also received preoperative thromboembolic prophylaxis.
The study of Charalambous C. et al. points to the importance of phlebography of the lower extremities in the diagnosis of deep venous thrombosis, because it can detect distal and proximal thrombosis, which is the most common cause of PTE. Phlebography of the lower extremities was not performed in our patient as part of the diagnostic procedures. In a prospective study of prophylactic anti-thrombotic therapy in orthopedic patients, color Doppler ultrasonography showed a low sensitivity in the detection of asymptomatic deep venous thrombosis in proximal leg veins of only 38% [8].  [8].
Geertsand et al. showed that thromboembolic prophylaxis reduces the incidence of PTE [9]. They have published a paper in which they showed that the high risk patients must preventively receive thromboembolic prophylaxis both pre-and postoperatively. After completion of surgical treatment, it is of utmost importance for patients at high risk to continue using thromboembolic prophylaxis as well as the recommended antiplatelet therapy [10].
In a review article, Unić-Stojanović D. showed that PTE may develop perioperatively in patients who have undergone drug and mechanical thromboembolic prophylaxis. She has also proven that the diagnosis is very difficult to make and it is accompanied by method of elimination. Intraoperative diagnosis is a major problem due to the similarity of clinical picture with other accompanying disorders such as bleeding and infection [11].
In their paper, Vučićević-Trobok J. et al. presented a patient with PTE that was associated with acute renal failure due to renal artery thrombosis. The patient was diagnosed with PTE and the therapeutic regime was initiated. On the third day of intensive treatment, hematuria appeared, followed by oliguria with a sharp elevation of nitrogenous substances in the blood, as a sign of acute renal failure. The patient died on the same day. The autopsy report revealed deep venous thrombosis of the left femoral vein, massive PTE, heart dilatation, and thrombosis of both renal arteries with numerous anemic infarcts which was the cause of acute renal failure [12].

Conclusion
There is an increased risk of pulmonary thromboembolism in orthopedic and trauma patients. The symptoms are most often nonspecific, so that early recognition with confirmation by diagnostic procedures is important in order to implement therapy and reduce the mortality rate.