Travel-Associated Venous Thromboembolism

INTRODUCTION

Long-distance travel is assumed to be a risk factor for venous thromboembolism (VTE). However, the available data have not clearly demonstrated the strength of this relationship, nor have they shown evidence for the role of thromboprophylaxis.

METHODS

We performed a systematic review of the literature. We also summarized available guidelines from 5 groups.

RESULTS

We found 18 studies that addressed this question. Based on the data presented in the review, we conclude that there is an association between VTE and length of travel, but this association is mild to moderate in effect size with odds ratios between 1.1 and 4. A dose-response relationship between VTE and travel time was identified, with a 26% higher risk for every 2 h of air travel (P=0.005) starting after 4 h. The quality of evidence for both travel length and thromboprophylaxis was low. However, low-risk prophylactic measures such as graduated compression stockings were shown to be effective in VTE prevention. There is heterogeneity among the different practice guidelines. The guidelines generally concur that no prophylaxis is necessary in travelers without known thrombosis risk factors and advocate for conservative treatment such as compression stockings over pharmacologic prophylaxis.

CONCLUSIONS

We conclude air travel is a risk factor for VTE and that there is a dose relationship starting at 4 h. For patients with risk factors, graduated compression stockings are effective prophylaxis.

Pulmonary embolism after a long-haul flight

The relation between long-haul flights (LHF) and venous thromboembolic disease is well established. Nonetheless, the incidence of pulmonary embolisms after these flights is probably underestimated because of the difficulties in case ascertainment. Reunion Island appears to present the ideal geographic conditions for accurately assessing this incidence. We aimed to assess the incidence of pulmonary embolisms in people who had recently taken a LHF to Reunion Island. We conducted a retrospective multi-center descriptive study and included all cases of pulmonary embolisms diagnosed between January 1, 2015, and January 30, 2017 (according to the hospitals' discharge summary database) in the island's four public hospitals within 30 days after taking an LHF to Reunion. We took different delays of diagnosis to calculate the incidence. We have considered the time to diagnosis at 1 month as significant according to the time applied in the Geneva score for risk factors. The study included 45 patients landing on Reunion over a 2-year period. The total number of passengers arriving by LHF during this period was 1,223,001. The incidence of pulmonary embolism after an LHF was thus calculated at 36.8 per million travelers at 1 month. The incidence for PE diagnosed, after 15 days was 29.4 per million travelers, and after 7 days, it was 21.9 per million travelers. The male/female ratio was 0.67. The mean interval between the flight and symptom onset was 7 days. In our population, the incidence of pulmonary embolisms after LHFs in our study is clearly higher than that reported in the literature (36.8 vs 4.8). Our exhaustive data collection probably explains this difference. A case-control study appears necessary to analyze the risk factors for pulmonary embolism after a LHF.

Detection of Pulmonary Embolism in Returning Travelers with Hypoxemic Pneumonia due to COVID-19 in Reunion Island

The aim of this study was to evaluate the occurrence of pulmonary embolism in returning travelers with hypoxemic pneumonia due to COVID-19. All returning travelers to Reunion Island with hypoxemic pneumonia due to COVID-19 underwent computed tomography pulmonary angiography (CTPA) and were included in the cohort. Thirty-five patients were returning travelers with hypoxemic pneumonia due to COVID-19 and had recently returned from one of the countries most affected by the COVID-19 outbreak (mainly from France and Comoros archipelago). Five patients (14.3%) were found to have pulmonary embolism and two (5.9%) were incidentally found to have deep vein thrombosis on CTPA. Patients with pulmonary embolism or deep vein thrombosis had higher D-dimer levels than those without pulmonary embolism or deep vein thrombosis (P = 0.04). Returning travelers with hypoxemic pneumonia due to COVID-19 should be systematically screened for pulmonary embolism.

Bilateral Pulmonary Embolism after a Short-Haul Flight in a Man with Multiple Risk Factors including Sickle Cell Trait

We report a case of pulmonary embolism (PE) in an Afro-Caribbean man following a short commercial flight of less than 5,000 kilometers (Km) in economy class with a 1-month interval between journeys. He had an elevated body mass index (BMI) and sickle cell trait (SCT) with hyperhomocysteinemia. No other preexisting source of venous thrombosis was found. We posit that venous thromboembolism (VTE) and/or PE may have been a complication of SCT in an individual with other multiple risk factors. We discuss the possible interaction of these risk factors for VTE and/or PE and the implications for travelers at risk. The need for a PE risk score and guidelines for the prophylaxis of thromboembolism among travelers exists.

Clinical Characteristics and Prognosis of Pulmonary Embolism Caused by Economy Class Syndrome

OBJECTIVE

Clinical presentation and short-term prognosis of patients with travel-associated acute pulmonary embolism (PE) (i.e., economy class syndrome [ECS]) is not well understood.

METHODS

In this retrospective cohort study of patients with acute PE identified from a single center registry, we assessed the clinical presentation and the association between ECS and the outcomes of all-cause mortality, PE-related mortality, nonfatal venous thromboembolism and nonfatal major bleeding rates through 30days after initiation of PE treatment.

RESULTS

Of the 2,333 patients with acute symptomatic PE, 124 (5.3%; 95% confidence interval, 4.4-6.3%) had ECS. Patients with ECS were younger and had fewer comorbid diseases (recent bleeding, chronic obstructive pulmonary disease, congestive heart failure), but they presented with more signs of clinical severity (syncope [48% vs. 14%; P<.001], tachycardia [37% vs. 21%; P<.001], right ventricular dysfunction [31% vs. 19%; P<.01] and myocardial injury [57% vs. 28%; P<.001]) compared to those without ECS. Regression analyses showed a significantly lower risk of all-cause mortality for patients with ECS compared to patients without ECS (1.6% vs. 9.6%; P<.01). We did not detect a difference in PE-related mortality at 30days between those with and those without ECS (0.8% vs. 3.1%; P=.18).

CONCLUSIONS

PE patients with ECS are younger and have fewer comorbid diseases compared to those without ECS. Though they present with more signs of clinical severity, their short-term prognosis is excellent.

Importance of risk factors for the evaluation of patients with a suspected pulmonary embolism

The reliable exclusion of a pulmonary embolism (PE) in hemodynamically stable patients remains a challenge. The European Society of Cardiology guidelines for PE diagnosis published in 2008 and updated in 2014 recommend a low-threshold computed tomography (CT) indication for patients with a high probability of pulmonary embolism or those with elevated levels of D-dimers. Certain elements of the recommendations are controversial, while others, including the evaluation of the risk factors for PE, are considered only in individual cases. In the present study, various risk factors, including obesity, smoking, contraceptive use, immobility level, history of malignant disease and thrombophilia and the factors of familial predisposition, deep vein thrombosis (DVT)/PE-history, long-distance flying <1 week and surgery <4 weeks previously, were retrospectively examined in 492 patients with a suspected PE. The data demonstrated a significant risk of PE with contraceptive use, a history of DVT/PE and thrombophilia. The immobility level, surgery <4 weeks and long-distance flying <1 week previously, as well as family history, malignant disease, obesity and smoking, were not observed to be associated with a significantly higher risk of PE. Contraceptive use and thrombophilia, in addition to a history of DVT/PE, each appear to have a significant predictive value in the context of PE risk stratification. Therefore, patients with a suspected PE, who additionally present with at least one of the aforementioned risk factors, should undergo further diagnostic steps for PE risk stratification, including a low-threshold CT examination, even in the absence of elevated D-dimers.

In-flight medical emergencies

BACKGROUND

One in every 10 000 to 40 000 passengers on commercial aircraft will have a medical incident while on board. Many physicians are unaware of the special features of the cabin atmosphere, the medical equipment available on airplanes, and the resulting opportunities for medical intervention.

METHODS

A selective literature search was performed and supplemented with international recommendations and guidelines and with data from the Lufthansa registry.

RESULTS

Data on in-flight medical emergencies have been collected in various ways, with varying results; it is generally agreed, however, that the more common incidents include gastrointestinal conditions (diarrhea, nausea, vomiting), circulatory collapse, hypertension, stroke, and headache (including migraine). Data from the Lufthansa registry for the years 2010 and 2011 reveal the rarity of cardiopulmonary resuscitation (mean: 8 cases per year), death (12 cases per year), childbirth (1 case per year), and psychiatric incidents (81 cases per year). If one assumes that one medical incident arises for every 10 000 passengers, and that there are 400 passengers on board each flight, then one can calculate that the probability of experiencing at least one medical incident reaches 95% after 24 intercontinental flights.

CONCLUSION

An in-flight medical emergency is an exceptional event for the physician and all other persons involved. Physician passengers can act more effectively if they are aware of the framework conditions, the available medical equipment, and the commonly encountered medical conditions.

Idiopathic (unexplained) pulmonary embolism is associated with an impaired prognosis compared to other entities of pulmonary embolism

In patients following acute pulmonary embolism, little is known about long-term prognosis attributed to individual risk factors and entities of pulmonary embolism. The aim of our study was to identify predictors of long-term mortality and morbidity, taking into account precipitating causes and entities of pulmonary embolism, especially in cases of idiopathic pulmonary embolism. We reviewed the records of 257 consecutive patients presenting with acute pulmonary embolism in the emergency room of the University Hospital in Frankfurt between 1997 and 2006. The median of the follow-up time in this study population was 670 days (n = 236; interquartile range: 378-1397 days). The patients were divided into three groups depending on the cause of pulmonary embolism: idiopathic pulmonary embolism (n = 83; 33%), neoplasm (n = 44; 17%) and other causes (n = 130; 50%). As expected, patients with neoplastic-associated pulmonary embolism demonstrated the poorest prognosis in the Kaplan-Meier analysis. Surprisingly though, patients with idiopathic pulmonary embolism demonstrated a markedly worse long-term survival compared with other causes (log-rank P < 0.001). When Cox-regression analysis was restricted to patients discharged alive without neoplasm, idiopathic pulmonary embolism was the strongest predictor of long-term mortality (hazard ratio: 3.29; P = 0.017). Patients with acute pulmonary embolism and known malignancy demonstrated the highest mortality compared with those with other causes. However, idiopathic pulmonary embolism is a common diagnosis and is associated with an unfavorable long-term prognosis compared with other entities of pulmonary embolism.