“The Road Less Travelled:” Pulmonary Embolism in a Long-distance Bus Passenger
Year: 2025
Type: article
Abstract: Sir, Pulmonary thromboembolism (PTE) refers to obstruction of the pulmonary artery or one of its branches by a venous thrombus originating elsewhere in the body. A quick diagnosis and effective management are essential to prevent the morbidity and mortality associated with pulmonary embolism. The clinical presentation is often variable and nonspecific due to which the patient’s underlying clinical condition or the presence of any provoking factor is important in the clinical suspicion of pulmonary embolism. Prolonged air travel is well documented as a provoking factor for pulmonary embolism, but land travel as a provoking factor is rare in medical literature.[1] We want to discuss a successfully managed case of pulmonary embolism provoked by prolonged bus travel. A 69-year-old male, never smoker with no known comorbidities presented to our hospital with complaints of swelling of the left lower limb and breathlessness on exertion of 1 week duration. The patient took a bus journey 1 week ago of 8-h duration following which he noticed swelling over his left lower limb extending from ankle to knee joint. One day after the event, he started developing breathlessness on exertion which was acute onset modified medical research council (mMRC) Grade II. The breathlessness progressed over the week to mMRC Grade IV. He gave a history of four episodes of syncope lasting for 1–2 min followed by palpitation and perspiration with spontaneous recovery. On presentation to our hospital, the patient was breathless even at rest, had pleuritic chest pain over the right infra-axillary region, and had persistent swelling over the left lower limb. He had no history of trauma, fever, weight loss, bleeding manifestations, or orthopnea. On evaluation, he had a heart rate of 108 beats/min, blood pressure of 116/74 mmHg, respiratory rate of 34 breaths/min, and maintained a saturation of 98% on room air. Systemic examination was unremarkable with normal bilateral breath sounds and heart sounds except for the left lower limb swelling extending from ankle to knee with no local raised temperature or erythema. He had a hemoglobin level of 14.3 g/dl, total leukocyte count of 11,600 cells/mm3, total platelets of 313,000/mm3, normal liver and renal function test, and normal electrolyte levels. Electrocardiogram taken showed sinus tachycardia with T-wave depression in V1, V2, and V3 chest leads. Troponin T and N-terminal pro-B-type natriuretic peptide levels were normal. Chest radiography taken was normal. He was clinically suspected to have deep vein thrombosis (DVT) of the left lower limb with pulmonary embolism (Well’s score 7.5) and was taken up for computed tomography pulmonary angiography which revealed acute pulmonary thrombus in bilateral 1st and 2nd order pulmonary artery (right > left) [Figure 1]. Lower limb Doppler studies showed DVT in the left popliteal vein. He was diagnosed with acute pulmonary embolism (low risk, sPESI 0) with left lower limb DVT and was started on therapeutic anticoagulation. A contrast-enhanced computed tomography of the abdomen and pelvis was taken to screen for malignancy and was found to be negative. The patient showed symptomatic improvement with therapeutic anticoagulation and was discharged after a week of hospitalization on the tablet apixaban.Figure 1: Computed tomography pulmonary angiography axial sections (a and b) and coronal reformats (c and d) showing eccentric hypodense filling defects in the right and left pulmonary arteries (straight white arrows) and the second-order pulmonary artery branches bilaterally (curved white arrows), suggestive of acute pulmonary thromboembolismMost pulmonary embolisms arise from the lower limb. DVT of the calf rarely embolises, whereas 50% of proximal vein DVT will have concurrent pulmonary embolism. The pathogenesis of pulmonary embolism can be explained by Virchow’s triad which is characterized by venous stasis, endothelial injury, and hypercoagulable state. Long haul travel is an interesting cause of lower limb venous stasis which can predispose to lower limb DVT. The term “economy class syndrome” was first used by Cruickshank in 1988 for his case description of pulmonary embolisms that developed in 3 patients after long-haul flights.[2] The term was later discontinued, and the more appropriate term of “traveller’s thrombosis” was adopted as any journey involving prolonged immobilization was seen to increase the risk of pulmonary embolism. Ferrari et al. compared the history of recent travel in 160 patients of venous thromboembolism to a control group and concluded that the odds ratio of PTE in patients who had a travel lasting >4 h was 3.98.[3] The risk of DVT in high-risk patients attempting long-distance travel is around 5% as per the LONFLIT 2 and LONFLIT 3 studies.[4,5] Most studies have linked a positive causative relation between long-haul air travel and PTE with a shortage of data regarding other forms of travel. Due to the predominance of the pathology in air travel, other causative factors such as hypoxemia, low air pressure, and alcohol-induced dehydration were also thought about.[1] The patient under discussion is among the rare cases wherein travellers’ thrombosis was precipitated by long-haul land travel. This highlights that prolonged immobilization of long-distance travel is an independent risk factor for PTE without associated hypoxemia and low air pressure. A high index of suspicion should be kept by the treating physician when a patient presents with acute onset breathlessness, chest pain, and limb swelling post travels more than 4 h. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Authors: V Shrinath, Sumita Singh, Rahul Dudhal, Ramamoorthy Ananthakrishnan
Institution: INHS Asvini
Language: English
Subfield: Internal Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W4408165169