Effects of long travels in sitting position in elderly volunteers on biological markers of coagulation activation and fibrinolysis

Annotation: travel and thrombosis

Travel appears to be a weak risk factor for venous thromboembolism (VTE) and is more relevant for passengers with additional VTE risk factors. The association is not limited to air travel and is related to duration of travel. Life-threatening pulmonary embolism (PE) is rare. There is limited evidence to support interventions, including 'sensible measures', graduated compression stockings (GCS) and low-molecular-weight heparin (LMWH). It is difficult to confidently define a population who would benefit from thromboprophylaxis and no validated risk assessment exists for this purpose. LMWH has traditionally been used for flight thromboprophylaxis but a direct oral anticoagulant (DOAC) would be a more appealing oral option.

Seasonal variation in the incidence of superficial venous thrombophlebitis

INTRODUCTION

Previous studies have demonstrated an increased frequency and severity of symptoms due to varicose veins during summer. However there is no data on their complications, including superficial venous thrombophlebitis (SVT). The aim of this study was to test the hypothesis that SVT follows a seasonal pattern.

MATERIALS AND METHODS

During the two-year period between January 2007 and December 2008, inclusive, 123 patients with SVT were evaluated, including 60 females and 63 males. In 8 patients (6.5%) an additional and/or other predisposing factor was present. On presentation, SVT was complicated by thrombus extension to the proximal deep system in 5 cases (4.1%); above-knee SVT was present in 4 of these 5 cases.

RESULTS

SVT occurred more often during the months of May through October (monthly incidence of 7.3 cases) compared to remaining of the year (monthly incidence of 2.9 cases). SVT showed a peak in June and July with 33.3% of all SVTs occurring during these two months (monthly incidence of 10.25 cases). Using time-series statistics SVT occurrence showed a periodical seasonal pattern (p=0.003). Although a seasonal pattern was evident in all patient subgroups, this was significant only in males and patients with below-knee SVT.

CONCLUSIONS

SVT showed a clear seasonal pattern of occurrence, with a significant rise during summer time. Although a possible explanation of this observation could be poor patient compliance and suboptimal usage of elastic stockings during the hot Mediterranean summer, further studies to investigate the cause, clinical significance and preventive methods of this complication are justified.

Travel-related thromboembolism: mechanisms and avoidance

Evidence regarding the existence of travel-related venous thrombosis and pulmonary embolism is building. Research suggests that travel of all kinds increases the risk by two- to four-fold. Risks are not restricted to air travel alone. For travelers without any known risk factors, the risk of experiencing venous thromboembolism is likely to be very low. However, risks increase significantly in the presence of known risk factors, such as age over 60 years, thrombophilic disorders, varicose veins, history of thromboembolism, obesity, women taking oral contraceptives and travel duration over 12 h. A combination of one or more of these risk factors raises the probability of developing travel-related thromboembolism. Possible contributing factors, such as cramped sitting (with suppressed leg venous flow), moderate hypoxia, low humidity in the aircraft and dehydration, are discussed. Depending on the risk profile of individuals, the use of graduated compression stockings and/or pharmacological interventions (low-molecular-weight heparins are preferred) may be recommended.

Travel thrombosis, 2008

Magyarországon a 2000-es évek elején jelentek meg az utazási trombózissal foglalkozó első közlemények. Ebben a tanulmányban áttekintjük a vénás trombózis e különleges formájával kapcsolatos új kutatási eredményeket. Az utazási trombózis az ülőtrombózisok alcsoportja, a tartós ülő helyzet következménye, amely a földi közlekedés és a légi utazás közös jellegzetessége. Egyre több, komputerhez kötött ülőtrombózist is megfigyelnek. A hosszú légi utazás során kialakuló vénás thromboembolia multifaktoriális betegség. A lehetséges rizikófaktorok a fedélzet környezetével kapcsolatosak. Különböző tanulmányok vizsgálták az immobilizáció és a hypobaricus hypoxia hatását a trombinképződésre és a fibrinolízisre. Ezek a vizsgálatok a résztvevők jellegzetességeit, az expozíció időtartamát és típusát, valamint a statisztikai analízist tekintve lényegesen eltérnek egymástól, így az eredmények is ellentmondóak. Személyes, az utasra vonatkozó rizikófaktorok indíthatják el a trombózis kialakulását. A betegség aktuális, pontos kockázatát a jelenleg rendelkezésünkre álló evidenciák alapján nem tudjuk megmondani. Egészséges fiatalokon a kockázat kicsi. Thromboemboliás rizikófaktorral rendelkező utasokon azonban az 5000 km-nél hosszabb repülés, a 8 óránál tovább tartó utazás komoly veszélyekkel jár. A megfelelő óvintézkedéseket a legújabb nemzetközi ajánlások segítségével foglaljuk össze.

[Risk of venous thromboembolism in the course of acute medical illness. Part 1: Basic research, clinical models, descriptive and analytic epidemiology]

PURPOSE

Some acute medical illnesses are associated with an increased risk of venous thromboembolism. This risk is difficult to assess in medical patients on account of the multiplicity of their pathologies, leading to potential interactions between numerous risk factors.

CURRENT KNOWLEDGE AND KEY POINTS

A rational analysis of the risk of venous thrombosis in acute medical setting may be derived from pathogenic models and be based on elementary risk factors for venous thromboembolism classified as transient, permanent, major and intermediate factors. The systematic study of pathophysiological mechanisms in process, in each medical patient could guide the physician attitude toward still non-evaluated situations.

FUTURE PROSPECTS AND PROJECTS

A synthesis of the last epidemiological and pathophysiological data is developed in the first part of this literature review, whereas the risk linked to specific situations in ambulatory, hospital or internal medicine settings will be described in the second part.

Travel and venous thrombosis: a systematic review

In the past decade, numerous publications on the association between venous thrombosis (VT) and travel have been published. Relative and absolute risks of VT after travel, and particularly after travel by air, have been studied in case-control and observational follow-up studies, whereas the effect of prophylaxis has been studied through intervention trials of asymptomatic clots. The mechanism responsible for the association between travel and VT was addressed in pathophysiologic studies. Here, we systematically reviewed the epidemiologic and pathophysiologic studies about the association between travel and VT. We conclude that long-distance travel increases the risk of VT approximately two to fourfold. The absolute risk of a symptomatic event within 4 weeks of flights longer than 4 h is 1/4600 flights. The risk of severe pulmonary embolism (PE) occurring immediately after air travel increases with duration of travel, up to 4.8 per million in flights longer than 12 h. The mechanism responsible for the increased risk of VT after (air) travel has insufficiently been studied to draw solid conclusions, but one controlled-study showed evidence for an additional mechanism to immobilization that could lead to coagulation activation after air travel.

The association between seated immobility and local lower-limb venous coagulability in healthy adult volunteers: a simulation of prolonged travel immobility

This is the first study to examine the hypothesis that prolonged sitting is associated with procoagulant changes in the local lower-limb venous system. A comparison was made with upper-limb venous changes. Changes in markers of thrombin generation, fibrinolysis, endothelial perturbation and haemoconcentration were analysed as 10 healthy adult male participants sat for 8 h. The change in foot volume was estimated. Subjective venous thromboembolism assessment was undertaken hourly, along with 2-week and 4-week safety follow-up for clinical events. Expected increases in median prothrombin fragments 1 and 2, thrombin-antithrombin complex and D-dimer were not observed in either limb. An increase greater than 45% in the median tissue plasminogen activator and plasminogen activator-1 molar ratio (t-PA/PAI-1), and a decrease greater than 15% in median soluble thrombomodulin were noted in both limbs. Median haematocrit decreased minimally (1%) in the lower limbs, while the foot volume increased by 4%. Subjects experienced vague symptoms after 6 h of sitting, but none developed symptomatic venous thromboembolism. Upper and lower-limb changes in biomarkers did not correlate, except those in t-PA/PAI-1 ratio and plasminogen activator-1. Significant correlation was found between changes in the lower-limb t-PA/PAI-1 ratio and right foot volume. This study originally reveals that even in the lower limbs, prolonged daytime cramped sitting is not associated with significant procoagulant changes in healthy adult male volunteers, and confirms a previous observation that local lower-limb venous changes are not identically reflected in the upper limbs.

Prolonged seated immobility-associated venous coagulability in a factor V Leiden heterozygote: a case-comparative study

Prolonged sitting and thrombophilia may compound the risk of venous thromboembolism. In order to investigate suspected local lower limb venous procoagulant changes associated with prolonged sitting-induced venous stasis in a man heterozygous for factor V Leiden (participant X), we qualitatively compared venous coagulability in lower and upper limb plasma in this participant and three other male Caucasians over 8 h of sitting. Of the four participants, participant X had the highest baseline values of prothrombin fragments 1 and 2, thrombin-antithrombin III complexes, tissue plasminogen activator, plasminogen activator inhibitor 1, D-dimer and soluble thrombomodulin. Over time, in participant X, venous prothrombin fragments 1 and 2, thrombin-antithrombin III complexes, and soluble thrombomodulin decreased in both limbs; D-dimer decreased in the lower limbs but increased in the upper limbs; the tissue plasminogen activator/plasminogen activator inhibitor 1 molar ratio increased in both limbs; and minimal changes were noted in haematocrit. A foot volume increase was associated with vague symptoms towards the end of the study. Overall, these changes were similar to those observed in other participants. It is concluded from this case comparison that prolonged sitting of 8 h duration under normal atmospheric conditions did not result in local, as well as systemic, procoagulant haemostatic responses in a heterozygote for factor V Leiden when compared with other healthy volunteers. However, this observed, possibly adaptive, response is more likely to be compromised in factor V Leiden subjects during continued or increased venous endothelial stress or in the presence of other venous thromboembolism risk factors.

Effects of Mild Leg Exercise in a Seated Position on Haemostatic Parameters Under Normobaric Hypoxic Conditions

This study tested the hypothesis that in humans mild leg exercise affects haemostasis in normobaric hypoxia and thus avoids the development of a deep venous thrombosis (DVT). Eight young men breathed in a 15.4% oxygen in nitrogen gas mixture for 2 hrs while seated at rest (R) or seated and performing a 3-min mild leg exercise program (Ex) at 15-min intervals to assess the impact of mild leg exercise on haemostatic parameters related to the risk of developing DVT, as has been discussed for hypobaric hypoxic conditions during commercial airline travel. Capillary blood gases were analysed every 30 min. Heart rate was monitored continuously. Haemostatic parameters were analysed from venous blood at the beginning, after 1 and 2 hrs, and after a 30-min resting period in normoxic conditions. Plasminogen-activator-inhibitor-1 diminished in both tests in hypoxia, but not after the resting period. Antithrombin-III decreased in R in the hypoxic period. Platelet count, international normalized ratio, partial thromboplastin time remained unchanged, as did highly sensitive parameters like tissue-plasminogen-activator, α2-antiplasmin, d-dimers, thrombin-antithrombin-III-complexes, and prothrombin-fragments 1 and 2. The haematocrit decreased significantly in R. The mild leg execise prevented the decrease of antithrombin-III and caused an increase in haematocrit after an initial drop in the first hour. The present study revealed that normobaric hypoxia did not have clinically relevant effects on haemostasis in humans. Mild leg exercise carried out under those conditions did not lead, via alterations in haemostasis, to a reduced risk of DVT. Key words: local aerobic exercise, haemostasis, hypoxia, thrombosis

Coagulation changes and edema formation during long-distance bus travel

Long-distance travel in a cramped position by aircraft or by bus and car has been suggested to be associated with an increased risk for thromboembolic events. Recently, we demonstrated moderate activation of coagulation after a long-haul flight. At present the single contributing factors (i.e. hypoxia and low humidity on board an aircraft and prolonged sitting in an aircraft, car or bus inducing venous stasis) have not yet been investigated. Therefore we measured markers of coagulation and fibrinolysis as well as functional parameters of coagulation using activated thrombelastography in 19 healthy volunteers before, during and after a real 10-h bus journey. In addition, changes in leg volume were measured. Thrombelastography revealed moderate activation of coagulation in all travelers, which was accompanied by a significant increase in prothrombin fragment F1 + 2. Thrombin-antithrombin III complexes and D-dimer remained unchanged, and tissue-type plasminogen activator and plasminogen-activator inhibitor 1 decreased after travel. After the travel we found a significant increase in leg volume that was exclusively distributed in the calf. We conclude that beside long-haul flights also long-distance bus travel induces a certain activation of the coagulation system. Thus, it is questionable whether hypoxia is the crucial risk factor for thromboembolic events after long-haul flights.