Prevention of edema,flight microangiopathy and venous thrombosis in long flights with elastic stockings. A randomized trial: The LONFLIT 4 Concorde Edema-SSL Study

The LONFLIT1/2 studies have established that in high-risk subjects after long (> 10 hours) flights the incidence of deep venous thrombosis (DVT) is between 4% and 6%. The LONFLIT4 study has been planned to evaluate the control of edema and DVT in low-medium-risk subjects. The aim of this study was to evaluate edema and its control with specific flight stockings, in long-haul flights. In the first part of the study 400 subjects at low-medium risk for DVT were contacted; 28 were excluded for several nonmedical problems; 372 were randomized into 2 groups to evaluate prophylaxis with stockings in 7-8-hour flights; the control group had no prophylaxis. Below-knee, Scholl, Flight Socks, producing 14-17 mm Hg of pressure at the ankle, were used in the treatment group. The occurrence of DVT was evaluated with high-resolution ultrasound scanning (femoral, popliteal, and tibial veins). Edema was assessed with a composite score based on parametric and nonparametric measurements. Part II: In this part of the study 285 subjects at low-medium risk for DVT were included and randomized into 2 groups to evaluate edema prophylaxis in 11-12-hour flights; the controls had no prophylaxis while the prevention group had below-knee, Scholl, Flight Socks (comparable to part I). RESULTS: Part 1: DVT evaluation. Of the 184 included subjects in the stockings group and 188 in the control group, 358 (96.2%) completed the study. Dropouts were due to compliance or connection problems. Age/sex distributions were comparable in the groups. Stockings Group: of 179 subjects (mean age 49; SD 7; M:F = 101:78), none had DVT or superficial thromboses. Control Group: of 179 subjects (mean age 48.4; SD 7.3; M:F = 98:81), 4 (2.2%) had a DVT. There were also 2 superficial thromboses. In total, 3.35% (6) subjects had a thrombotic event. The difference (p<0.002) is significant. Intention-to-treat analysis detects 15 failures in the control group (9 lost + 6 thromboses) out of 188 subjects (7.9%) versus 5 subjects (2.7%) in the stockings group (p <0.05). All thrombotic events were observed in passengers sitting in nonaisle seats. The tolerability of the stockings was very good and there were no complaints or side effects. Thrombotic events were asymptomatic. No difference was observed in the distribution of events between men and women. The 3 women who had a thrombotic event were taking low-dose, oral contraceptives. Edema evaluation: The level of edema at inclusion was comparable in the 2 groups. After the flight there was a score of 6.7 (3.1) in controls; in the stockings group the score was 2.9 times lower (p<0.05). The control of edema with stockings was clear considering both parametric (circumference, volume) and nonparametric (analogue scale lines) data. Part II: DVT evaluation. Of the 285 included subjects, 271 (95%) completed the study. Dropouts were due to low compliance or connection problems. Age/sex distributions were comparable in the groups. Stockings Group: of 142 subjects (mean age 48; SD 8; M:F = 89:53), none had DVT or superficial thromboses. Control Group: of 143 subjects (mean age 47; SD 8; M:F = 87:56), 3 had a popliteal DVT and 3 a superficial thrombosis. In total, 4.2% (6) subjects had a thrombotic event. The difference (p<0.02) between groups is significant. Intention-to-treat analysis detects 14 failures in the control group (8 lost + 6 thromboses = 9.7%) versus 6 (all lost = 4.2% in the stockings group) (p<0.05). Four of 6 events (3 DVT + 1 SVT) were observed in non-aisle seats. The tolerability of the stockings was very good. No difference was observed in the distribution of events between men and women. Edema evaluation: The level of edema at inclusion was comparable in the 2 groups. After the flight there was a score of 8.08 (2.9) in controls while in the stockings group the score was 2.56 (1.5) (p < 0.005). In conclusion. Scholl Flight Socks are very effective in controlling edema. Also this type of compression is effective in significantly reducing the incidence of DVT and thrombotic events in low-medium-risk subjects, in long-haul flights. CONCLUSIONS: Considering these observations, Flight Socks are effective in controlling edema and in reducing the incidence of DVT in low-medium-risk subjects, in long-haul flights (7-11 hours).     

The LONFLIT4-Concorde--Sigvaris Traveno Stockings in Long Flights (EcoTraS) Study: a randomized trial

The LONFLIT1/2 studies have established that in high-risk subjects after long ( > 10 hours) flights the incidence of deep venous thrombosis (DVT) may be between 4% and 6%. The LONFLIT4 study was aimed at evaluating the control of edema and DVT prevention in low-medium-risk subjects. In this study prophylaxis of edema with specific travel stockings was evaluated in 2 separate studies involving flights lasting 7 hours and 10-12 hours. Part I. Subjects at low-medium risk for DVT were contacted; 55 subjects were excluded for several nonmedical, travel-related problems or inconvenient evaluation time; the remaining 211 were randomized into 2 groups to evaluate prophylaxis with elastic stockings in 7-8-hour, long-haul flights. The control group had no prophylaxis; the treatment group used below-knee, Sigvaris Traveno elastic stockings (Ganzoni, Switzerland, producing 12-18 mm Hg of pressure at the ankle). Color duplex scanning was used to evaluate the possible presence of DVT; edema/swelling were evaluated with a composite score including the presence of edema (with an edema tester), variations in ankle circumference and leg volumetry, subjective swelling, and discomfort (scale ranging from 0 to 10). Results: Of the 103 included subjects in the stockings group and 108 in the control group (total 211), 195 subjects completed the study. Dropouts (16) were due to low compliance or traveling and connection problems. Age, sex distribution, and risk factors distributions were comparable in the 2 groups. Stockings Group: Of 97 subjects none had DVT or superficial thromboses. Control Group: Of 98 subjects none had thrombosis. The level of edema at inclusion was comparable in the 2 groups of subjects. After flights there was an average score of 6.4 (1.3) in the control group, while in the stockings group the score was on average 2.4 (SD 1), 2.6 times lower than in the control group (p < 0.05). In the control group 83% of the subjects had an evident increase in ankle circumference and volume that was visible at inspection and associated with discomfort. The control of edema with stockings was clear, considering both parametric data (circumference and volume) and nonparametric (analogue scale lines) measurements. Part II. In this part of the study 200 subjects at low-medium risk for DVT were contacted; 35 subjects were excluded for several nonmedical, travel-related problems or inconvenient evaluation time; the remaining 165 were randomized into 2 groups to evaluate prevention in flights lasting between 11 and 12 hours. The control group had no prophylaxis; the treatment group used Traveno stockings. Of the 83 included subjects in the stockings group and 82 in the control group (total 165), 146 subjects completed the study. Dropouts were due to low compliance or connection problems. Age/sex distribution were comparable. Of 75 subjects completing the study in the stockings group and 71 in the control group, none had thrombosis. The average level of edema at inclusion was comparable in the 2 groups (1.1). After the flight there was a score of 8.9 (2) in controls; in the stockings group the score was 2.56 (1.3) (p < 0.05). The control of edema and swelling with stockings even after 11 hours of flight was clear, considering both parametric (circumference, volume) and nonparametric (analogue scale lines) measurements. The tolerability of the stockings was very good and there were no complaints or side effects. In conclusion Sigvaris Traveno stockings are very effective in controlling edema in long-haul flights.     

The LONFLIT4-Venoruton Study: a randomized trial--prophylaxis of flight-edema in venous patients

The aim of this independent study was to evaluate the protective effects, on the development of flight edema, of Venoruton. The study included patients with venous disease traveling in economy in long-haul flights (9 hours). Edema is a relevant aspect of long-haul flights affecting both patients with venous disease and normal subjects. Microcirculatory variations during flights cause a microangiopathy and biochemical and coagulation alterations. This condition may be defined as flight microangiopathy. A group of 203 subjects with chronic venous disease (uncomplicated varicose veins) at low-medium risk for DVT were contacted; 43 subjects were excluded for several nonmedical, travel-related problems or inconvenient evaluation time; the remaining 160 were randomized, after informed consent, into 2 groups to evaluate 2 prophylaxes in 7-8-hour, long-haul flights: The treatment group received Venoruton (hydroxyethyl rutosides) 1 g twice daily for 3 days (2 days before the flight and the day of the flight). The control group received comparable placebo. The edema score was based on the edema tester, ankle circumference, volume measurements, subjective swelling, and discomfort score. Items 1, 4, and 5 are based on an analogue scale line (1 to 10) directly defined by the subjects before and after the flights. Of the 160 included subjects 139 completed the study. Dropouts (21) were due to poor compliance, traveling, and/or connection problems (11 in the control group, 10 in the treatment group). Age and sex distribution were comparable in the 2 groups as were risk factors distributions. The level of edema at inclusion was comparable in the 2 groups of subjects. After the flight there was an average score of 7.2 (sd 2) in the control group, while in the Venoruton group the score was on average 3.2. (sd 1.1) (p < 0.05), 2.25 times lower than in the control group (p < 0.05). In the control group 89% of the subjects had an evident increase in ankle circumference and volume, which was clearly visible at inspection and associated with discomfort. In the Venoruton group edema was clearly present in 12% of subjects (associated with discomfort between 5 and 7 on the analogue scale line) and it was mild-moderate, not associated with symptoms (pain, discomfort between 2 and 4 on the analogue scale line). Therefore, the control of flight edema with Venoruton was clear both considering parametric data (circumference and volume) and nonparametric (analogue scale lines) measurements. The combined evaluation of the edema score is significantly favorable for patients treated with Venoruton. No deep vein thrombosis or superficial vein thrombosis was observed in this study.     

Venous thromboembolism from air travel: the LONFLIT study.

The LONFLIT study was planned to evaluate the incidence of deep venous thrombosis (DVT) occurring as a consequence of long flights. In the Lonflit study 355 subjects at low-risk for DVT and 389 at high-risk were studied. Low-risk subjects had no cardiovascular disease and used no drugs. All flights were in economy class. The average flight duration was 12.4 hours (range, 10-15 hr). The mean age of the studied subjects was 46 years (range 20-80 yr, SD 11; 56% males). DVT diagnosis was made by ultrasound scans after the flights (within 24 hours). In low-risk subjects no events were recorded while in high-risk subjects 11 had DVT (2.8%) with 13 thromboses in 11 subjects and 6 superficial thromboses (total of 19 thrombotic events in 389 patients [4.9%]). In the Lonflit2 study the authors studied 833 subjects (randomized into 422 control subjects and 411 using below-knee stockings). Mean age was 44.8 years (range, 20-80 yr, SD 12; 57% males). The average flight duration was 12.4 hours. Scans were made before and after the flights. In the control group there were 4.5% of subjects with DVT while only 0.24% of subjects had DVT in the stockings group. The difference was significant. The incidence of DVT observed when subjects were wearing stockings was 18.75 times lower than in controls. Long-haul flights are associated to DVT in some 4-5% of high-risk subjects. Below-knee stockings are beneficial in reducing the incidence of DVT.     

Prevention of venous thrombosis in long-haul flights with Flite Tabs: the LONFLIT-FLITE randomized, controlled trial

The aim of this study was to evaluate the development of edema, and superficial and deep vein thrombosis (DVT) prophylaxis with an oral profibrinolytic agent (Flite Tabs, 150 mg pinokinase, Aidan, Tempe, AZ, USA) in long-haul flights (7-8 hours), in high-risk subjects. A group of 300 subjects was included; 76 were excluded for several problems including concomitant treatments; 204 were randomized into 2 groups (active treatment or placebo) to evaluate the effects of prophylaxis with Flite Tabs. An exercise program was used in both groups. The femoral, popliteal, tibial, and superficial veins were scanned with ultrasound before and within 90 minutes after flights. Of the included subjects, 92 of 103 controls and 94 of 101 treated subjects completed the study. Dropouts were due to connection problems. Age, gender, and risk distribution were comparable in the groups. In the treatment group, no DVT was observed. In the control group, 5 subjects (5.4%) had a DVT and there were 2 superficial thromboses (7 events in 92 subjects; 7.6%). At inclusion, edema was comparable in the 2 groups. After flights there was an increase in score in controls (+12%) in comparison with a decrease (-15%) in the Flite Tabs group (the difference in variation was statistically significant). Intention-to-treat analysis for thrombotic events shows 18 failures in controls (11 lost to follow-up + 7 thrombotic events) of 92 subjects (19.6%) in comparison with 7 failures (of 94 subjects, equivalent to 7.4%) in the treatment group (p < 0.05). Events were asymptomatic. In conclusion, Flite Tabs were effective in reducing thrombotic events and in controlling edema in high-risk subjects in long flights.     

Venous thrombosis from air travel: the LONFLIT3 study--prevention with aspirin vs low-molecular-weight heparin (LMWH) in high-risk subjects: a randomized trial

The LONFLIT1 and 2 studies established that in high-risk subjects after long (>10 hours) flights, the incidence of deep venous thrombosis (DVT) may be between 4% and 6%, The LONFLIT3 study aimed to evaluate methods of prevention in high-risk subjects. Of 467 subjects contacted for the study, 300 were included. These 300 subjects at high risk for DVT were randomized, after informed consent, into three groups: 1) a control group that had no prophylaxis; 2) an aspirin treatment group, in which patients were treated with 400 mg (tablets of oral, soluble aspirin; one dose daily for 3 days, starting 12 hours before the beginning of the flight); and 3) a low-molecular-weight heparin (LMWH) group, in which one dose of enoxaparine was injected between 2 and 4 hours before the flight. The dose was weight-adjusted (1,000 IU [equivalent to 0.1 mL per 10 kg of body weight). Subjects with potential problems due to prophylaxis with aspirin or LMWH or at risk of drug interactions were excluded. Of the 100 included subjects in each group, a total of 249 subjects completed the study (dropouts due to low compliance or traveling/connections problems were 17%). Age and sex distribution were comparable in the three groups as well as risk distributions. Mean age was 47 (range, 28-75; SD, 11; 65% males). Of the 82 subjects in the control group, there were 4.82% of subjects with DVT with two superficial thromboses. In total 4.8% of limbs suffered a thrombotic event. Of 84 subjects in the aspirin treatment group, there were 3.6% of patients with DVT and three superficial thrombosis. In total 3.6% of limbs had a thrombotic event. In the LMWH group (82 subjects), there were no cases of DVT. One superficial thrombosis was documented. In total only 0.6% of limbs had a thrombotic event (p<0.002 in comparison with the other two groups). DVT was asymptomatic in 60% of subjects; 85% of DVTs were observed in passengers in non-aisle seats. Mild gastrointestinal symptoms were reported in 13% of patients taking aspirin. One dose of LMWH is an important option to consider in high-risk subjects during long-haul flights.     

Prevention of venous thrombosis and thrombophlebitis in long-haul flights with pycnogenol.

The aim of this study was to evaluate the occurrence of deep venous thrombosis (DVT) and superficial vein thrombosis (SVT) and its prophylaxis with an oral anti-edema and antithrombotic agent (Pycnogenol, Horphag, Research Management SA, Geneva, Switzerland) in long-haul flights, in subjects at moderate to high-risk of DVT and SVT. The study pre-included 244 pre-selected subjects; 211 were included (33 were excluded for several reasons due to logistic problems) and 198 completed the study; 13 subjects were lost for follow-up at the end of the flight, all for non-medical problems (i.e., for difficult connections). All subjects were scanned within 90 minutes before the flight and within 2 hours after disembarking. Subjects were supplemented with 100 mg Pycnogenol per capsule. Treatment subjects received two capsules between 2 and 3 hours before flights with 250 mL of water; two capsules were taken 6 hours later with 250 mL of water and one capsule the next day. The control group received comparable placebo at the same intervals. The flight duration was on average 8 hours and 15 minutes (SD 55 min) (range, 7.45-12.33). In the control group there were five thrombotic events (one DVT and four superficial thromboses) while only nonthrombotic, localized phlebitis was observed in the Pycnogenol group (5.15% vs. no events; p<0.025). The ITT (intention to treat) analysis detects 13 failures in the control group (eight lost to follow up + five thrombotic events) of 105 subjects (12.4%) vs. five failures (4.7%; all lost, no thrombotic events) in the treatment group (p<0.025). No unwanted effects were observed. In conclusion, this study indicates that Pycnogenol treatment was effective in decreasing the number of thrombotic events (DVT and SVT) in moderate-to-high risk subjects, during long-haul flights.     

Prevention of edema and flight microangiopathy with Venoruton (HR), (0-[beta-hydroxyethyl]-rutosides) in patients with varicose veins

The aim of this open study was the evaluation of the effects of HR (Venoruton) at a dose of 1 g/day on the prevention and control of flight microangiopathy and edema in subjects with varicose veins and moderate chronic venous insufficiency flying for more than 11 hours. Patients with varicose veins, edema, but without initial skin alterations or complications, were included. Measurements of skin laser Doppler (LDF) resting flux (RF) venoarteriolar response (VAR), ankle swelling (RAS), and edema were made within 12 hours before and within 3 hours after the flights. The resulting edema after the flights was evaluated with a composite edema score (analogue scale line). A group of 20 subjects was treated with HR (1 g/day, starting 2 days before the flight and 1 g for every 12 hours on day of travel). Another group of 18 subjects formed the control group. The length of the flights was between 11 and 13 hours; all seats were in coach class. Fifty patients were enrolled and 38 patients were evaluable at the end of the trial. The 2 groups (treatment and control) were comparable for age and sex distribution. The decrease in RF was significant in both groups with a higher flux at the end of the flight in the HR group (p < 0.05). The venoarteriolar response was decreased at the end of the flights; the decrease was lower in the HR group (p < 0.05). The increase in RAS and the edema score were significantly lower in the HR group. In conclusion HR is useful for reducing the level of microangiopathy and the increased capillary filtration and in controlling edema in patients with venous disease in long flights. The higher level of flux and VAR and the reduction in edema indicate a positive effect of HR on the microcirculation. This study confirms that HR prophylaxis is effective to control flight microangiopathy associated with edema.     

Prevention of edema in long flights with Pycnogenol.

The aim of this study was to evaluate the prevention of edema during long-haul flights with an oral, anti-edema and antithrombotic agent (Pycnogenol, Horphag, Research Management SA, Geneva, Switzerland) in asymptomatic subjects. The assessment of edema was performed by evaluating an analogue scale, the rate of ankle swelling by strain-gauge derived rate of ankle swelling (RAS), and by assessing the ankle circumference variation. The study included 211 subjects; 169 completed the study (88 in the control group and 81 in the Pycnogenol group). There were no important differences between the two groups (comparable for age, gender, weight, body mass index, and pattern distribution). The edema score, the RAS, and the circumference at inclusion were also comparable. After the flight in those treated with Pycnogenol, the edema score was increased only by 17.9% (vs. an increase of 58.3% in the control group) (p<0.05). The RAS, evaluated in 22 subjects in the Pycnogenol group (age 44.5; SD 8) and in 23 in the control group (age 45; SD 9) was increased on average by 91% in the control group and 36% in the Pycnogenol group (p<0.05). The variation on circumference at the ankle was 6% in the Pycnogenol group (11% in the control group; p<0.05). These results indicate a positive effect of Pycnogenol on edema during long flights when considering subjective and objective data. No unwanted effects were observed.     

Knee-length graduated compression stockings for thromboprophylaxis in air travellers: A meta-analysis

OBJECTIVE:

To systematically review the randomized controlled trials that have evaluated the efficacy of knee-length (KL) compression stockings for thromboprophylaxis in air travellers.

METHOD:

After an electronic database search, the randomized controlled trials that studied passengers on long-haul flights were selected and analyzed to generate summative data.

RESULTS:

Nine trials studying participants using KL stockings were analyzed. Forty-six of 1261 participants randomly assigned to the control group developed deep vein thrombosis (DVT), compared with two of 1237 participants (0.16%) in the KL stockings group. The weighted risk difference was −0.034, which indicated that the absolute difference was 3.4% in the incidence of DVT, in favour of KL stockings. The number needed to treat with KL stockings to avoid one case of DVT was 29.4. However, there was significant heterogeneity among trials. The RR for DVT was 0.08 in high-risk participants and 0.14 in low- to medium-risk participants.

CONCLUSION:

KL stockings are effective for thromboprophylaxis in air travellers at low, medium and high risk of DVT. The use of KL stockings should form an important part of air traveller education on lowering the burden of DVT. The results of the present meta-analysis can be used to advise travellers on their risk of DVT and preventive strategies.     

Venous thrombosis after long-haul flights

BACKGROUND: The risk for venous thromboembolism after long-haul flights represents a controversial issue. The aim of our study was to assess the incidence of venous thrombosis associated with long-haul flights in a prospective, controlled cohort study. METHODS: We included 964 passengers returning from long-haul flights (flight duration, > or =8 hours) and 1213 nontraveling control subjects. We excluded participants who were being treated with anticoagulant drugs or who used compression stockings. Main outcome measures were the incidence of ultrasonographically diagnosed thrombosis in the calf muscle and deep veins, symptomatic pulmonary embolism, and death. RESULTS: We diagnosed venous thrombotic events in 27 passengers (2.8%) and 12 controls (1.0%) (risk ratio [RR], 2.83; 95% confidence interval [CI], 1.46-5.49). Of these, 20 passengers (2.1%) and 10 controls (0.8%) presented with isolated calf muscle venous thrombosis (RR, 2.52; 95% CI, 1.20-5.26), whereas 7 passengers (0.7%) and 2 controls (0.2%) presented with deep venous thrombosis (RR, 4.40; 95% CI, 1.04-18.62). Symptomatic pulmonary embolism was diagnosed in 1 passenger with deep venous thrombosis (P =.44). All of these individuals had normal findings at baseline ultrasonography. Passengers with isolated calf muscle venous thrombosis or deep venous thrombosis had at least 1 risk factor for venous thrombosis (>45 years of age or elevated body mass index in 21 of 27 passengers). The follow-up after 4 weeks revealed no further venous thromboembolic event. CONCLUSIONS: Long-haul flights of 8 hours and longer double the risk for isolated calf muscle venous thrombosis. This translates into an increased risk for deep venous thrombosis as well. In our study, flight-associated thrombosis occurred exclusively in passengers with well-established risk factors for venous thrombosis.     

Air travel and the risk of thromboembolism

Almost two billion people use commercial aircraft annually. Long-haul flights are taken by over 300 million people. A serious complication of long-distance travel (or prolonged time of flight) is thromboembolism. The real incidence of the problem is difficult to evaluate since there is no consensus about the diagnostic tests or limitation of time after landing connected to the VTE complication. A direct relation between VTE incidence and long-distance flights has been documented. The risk for DVT is 3–12% in a long-haul flight. The pathophysiologic changes that increase VTE risk at flight are stasis (sitting in crowded condition), hypoxia in the airplane cabin, and dehydration. Individual risk factors for air travel-related VTE include age over 40 years, gender (female), women who use oral contraceptives, varicose veins in lower limbs, obesity and genetic thrombophilia. Prevention measures include environmental protection such as keeping the pressure inside the airplane cabinet in hypobaric condition, avoiding dehydration and prolonged sitting. For individuals at increased risk, venous blood stasis can be reduced by wearing elastic stockings and prophylactic use of low-molecular-weight heparin.     

Air Travel and Venous Thromboembolism: A Systematic Review

CONTEXT: Despite multiple attempts to document and quantify the danger of venous thromboembolism (VTE) following prolonged travel, there is still uncertainty about the magnitude of risk and what can be done to lower it. OBJECTIVES: To review the methodologic strength of the literature, estimate the risk of travel-related VTE, evaluate the efficacy of preventive treatments, and develop evidence-based recommendations for practice. DATA SOURCES: Studies identified from MEDLINE from 1966 through December 2005, supplemented by a review of the Cochrane Central Registry of Controlled Trials, the Database of Abstracts of Reviews of Effects, and relevant bibliographies. STUDY SELECTION: We included all clinical studies that either reported primary data concerning travel as a risk factor for VTE or tested preventive measures for travel-related VTE. DATA EXTRACTION AND ANALYSIS: Two reviewers reviewed each study independently to assess inclusion criteria, classify research design, and rate methodologic features. The effect of methodologic differences, VTE risk, and travel duration on VTE rate was evaluated using a logistic regression model. DATA SYNTHESIS: Twenty-four published reports, totaling 25 studies, met inclusion criteria (6 case-control studies, 10 cohort studies, and 9 randomized controlled trials). Method of screening for VTE [screening ultrasound compared to usual clinical care, odds ratio (OR) 390], outcome measure [all VTE compared to pulmonary embolism (PE) only, OR 21], duration of travel (<6 hours compared to 6-8 hours, OR 0.011), and clinical risk ("higher" risk travelers compared to "lower," OR 3.6) were significantly related to VTE rate. Clinical VTE after prolonged travel is rare [27 PE per million flights diagnosed through usual clinical care, 0.05% symptomatic deep venous thrombosis (DVT) diagnosed through screening ultrasounds], but asymptomatic thrombi of uncertain clinical significance are more common. Graduated compression stockings prevented travel-related VTE (P < 0.05 in 4 of 6 studies), aspirin did not, and low-molecular-weight heparin (LMWH) showed a trend toward efficacy in one study. CONCLUSIONS: All travelers, regardless of VTE risk, should avoid dehydration and frequently exercise leg muscles. Travelers on a flight of less than 6 hours and those with no known risk factors for VTE, regardless of the duration of the flight, do not need DVT prophylaxis. Travelers with 1 or more risk factors for VTE should consider graduated compression stockings and/or LMWH for flights longer than 6 hours.     

Deep vein and isolated calf muscle vein thrombosis following long-haul flights: pilot study.

The risk of venous thromboembolism associated with long-haul flights is the subject of controversy. In a prospective, controlled study, we examined 160 passengers before and after return from a long-haul flight and 160 age-matched and sex-matched, non-travelling volunteers using venous compression ultrasound. Deep vein thrombosis was not observed in either group. Isolated calf muscle vein thrombosis (ICMVT) was present in 4/160 (2.5%) flight passengers and in 1/160 (0.6%) controls. All subjects with ICMVT were clinically asymptomatic, and ICMVT was located in the soleal muscle veins in all four subjects. Three of the four passengers with ICMVT had other risk factors for thrombosis.     

Flight microangiopathy in medium- to long-distance flights: prevention of edema and microcirculation alterations with total triterpenic fraction of Centella asiatica

The aim of this study was the evaluation of microcirculatory alterations associated with edema in passengers travelling for more than 3 hours and the study of the effects of TTFCA (total triterpenic fraction of Centella asiatica) on the development of microcirculation alterations and edema, in a prospective, randomized study. Laser Doppler flowmetry (LDF), transcutaneous PO2 and PCO2, rate of ankle swelling (RAS) were used. Subjects were randomized after informed consent into two groups: one control group (no drug or other treatment), and a treatment group (TTFCA 60 mg thrice daily for 2 days before the flight, the day of the flight, and for another day after the flight). Inclusion criteria were age range between 30 and 50, mild-moderate superficial venous disease with varicose veins. Subjects traveled in economy class. In controls there was a progressive increase in CO2, RAS, and edema score and a progressive decrease in flux (RF) and venoarteriolar response with flying time. The variations in all parameters were milder (p>0.05) in the TTFCA group. RAS and edema were significantly lower in the TTFCA-treated group (p<0.025). The progressive increase in RAS, PCO2, and the decrease in VAR and O2 were linearly associated with flight time (up to 10 hours). These results are very interesting and indicate an option for patients prone to edema and microcirculation disturbances during long flights.     

Incidence of air travel-related pulmonary embolism at the Madrid-Barajas airport

BACKGROUND: Prolonged air travel and the associated immobilization are risk factors for venous thromboembolism. The occurrence of pulmonary thromboembolism (PTE) under these circumstances is referred to as economy class syndrome. We assessed the incidence of symptomatic PTE in passengers on long-haul flights arriving at Madrid-Barajas Airport, Madrid, Spain, and the association with the number of flight hours. METHODS: We retrospectively reviewed cases of PTE among international travelers arriving at Madrid-Barajas Airport between January 1995 and December 2000. Patients presenting with symptoms of deep venous thrombosis but without symptoms of PTE were excluded. Pulmonary thromboembolism was identified using an algorithm of diagnostic tests. The incidence of PTE and the association with flight duration was assessed. RESULTS: The average number of passengers per year who arrived at the airport on flights originating abroad in the period analyzed was 6 839 222. Sixteen cases of PTE were detected over the 6-year period. All patients with travel-associated PTE had flight durations of greater than 6 hours. The overall incidence of PTE was 0.39 per 1 million passengers (95% confidence interval [CI], 0.20-0.58). On flights that lasted between 6 and 8 hours, the incidence was 0.25 per 1 million passengers (95% CI, 0-0.75), while on flights longer than 8 hours, the incidence was 1.65 per 1 million passengers (95% CI, 0.81-2.49) (P<.001). CONCLUSIONS: Air travel is a risk factor for PTE, and the incidence of PTE increases with the duration of the air travel. However, the low incidence of PTE among long-distance passengers, similar to that observed in other international airports, does not justify social alarm.     

Effectiveness and safety of hydroxyethyl-rutosides in the local treatment of symptoms of venous insufficiency during air travel]

During air travel, the length of time spent in a sitting position and the absence of muscular activity in the calves severely slow the rate of blood flow in the lower limbs. The aim of this randomized, cross-over, double-blind study was to evaluate local application of Hydroxyethyl-rutosides (O-Beta-Hydroxyethylrutosides) in the treatment of symptoms of venous insufficiency including stasis-induced edema during extended air travel on flights exceeding 6 hours. Hydroxyethyl-rutosides or placebo was applied every 3 or 4 hours throughout the flight. In the 51 subjects evaluated (both males and females) the results show statistically significant differences favoring treatment with Hydroxyethyl-rutosides both with regard to objective signs of edema: change in minimum ankle circumference was less during trips in which Hydroxyethyl-rutosides was applied, whether compared with the maximum measurement (p = 0.04) or the last measurement made during the flights, and with regard to subjective signs: several symptoms occurred significantly less frequently when the subject applied Hydroxyethyl-rutosides during the flight [pain (p = 0.03), sensation of heavy and tired legs (p = 0.04) and sensation of swelling (p = 0.02)]. the patient's overall assessment of the treatment was also favorable after using Hydroxyethyl-rutosides Gel (p = 0.01). the number of subjects complaining of edema (pitting edema, marks of shoes, difficulties putting shoes back on) was significantly lower during periods of treatment with Hydroxyethyl-rutosides Gel (p = 0.001). Local application of Hydroxyethyl-rutosides, 3 to 4 times during 6 to 14 hours is thus effective in treating the main symptoms of venous insufficiency including stasis-induced edema caused by extended periods in the sitting position during long air flights.     

Postthrombotic syndrome: incidence, prevention, and management

Mild to severe postthrombotic sequelae, including chronic pain, edema, and ulceration, arise in one third of patients short after deep vein thrombosis (DVT). Recurrent DVT is closely associated with the development of postthrombotic syndrome (PTS), whereas if the extent and location of DVT might be relevant remains unclear. Chronic venous hypertension and abnormal microvessel or lymphatic function also correlates with PTS. The diagnosis of PTS is based on clinical grounds only if patients report a history of documented DVT; otherwise, objective testing is required. To abate the prevalence of PTS, the best policy is represented by prevention of recurrent thrombosis and use of stockings. Despite a plenty of surgical options, conservative treatment is preferable because half of the patients improve or remain stable during follow-up, provided they wear elastic stockings. Clinical presentation has a prognostic value, as patients with initially severe symptoms enjoy a more favorable outcome than those who progressively deteriorate over time.     

Diabetic microangiopathy treated with elastic compression--a microcirculatory evaluation using laser-Doppler flowmetry, transcutaneous PO2/PCO2 and capillary permeability measurements

One hundred and forty patients with diabetic microangiopathy were studied by laser-Doppler flowmetry--measuring skin blood flow at rest (RF) and the venoarteriolar response (VAR)--by transcutaneous PO2 and PCO2 measurements and by evaluation of capillary permeability (rate of ankle swelling = RAS). Seventy were treated for 12 months with below-knee, elastic stockings. Seventy patients were left without compression acting as a control group. After 5 and 12 months there were no significant changes in the control group. However there was a significant improvement of microcirculatory parameters in patients treated with elastic compression. RF (increased at the beginning of the study) decreased. The VAR (impaired at the beginning of the study) improved significantly. PO2 (increased after treatment) and PCO2 (decreased) were also positively changed by elastic stockings. The abnormally increased capillary permeability was also improved. Elastic compression seems to be useful in diabetic microangiopathy improving microcirculatory parameters and decreasing capillary permeability and edema. However further studies, treating with elastic compression more patients for longer periods, are needed to confirm the positive effects of elastic stockings in improving diabetic microangiopathy and in slowing down its rate of progression.     

Prevention and treatment of postphlebitic syndrome: results of a 3-part study

BACKGROUND: The true incidence of postphlebitic syndrome (PPS) following proximal deep venous thrombosis (DVT) and the efficacy of graduated compression stockings in preventing and treating PPS are unknown. METHODS: A 3-part study of 202 patients evaluated 1 year after proximal DVT: 2 randomized placebo-controlled trials of stockings and 1 prospective cohort of untreated patients. Patients were evaluated for PPS, using a standardized questionnaire, and for venous valvular incompetence, using photoplethysmography and venous Doppler. They were enrolled in study 1 or study 2 if they did not have symptomatic PPS and did not have or had venous valvular incompetence, respectively, and into study 3 if they had symptomatic PPS. Study 1 patients were left untreated and followed up for development of PPS every 6 months for a mean of 55 months. Study 2 patients were randomized to a below-knee stocking (20-30 mm Hg) or a matched placebo stocking, and followed up for development of PPS every 6 months for a mean of 57 months. Study 3 patients were randomized to an active stocking (30-40 mm Hg) or a matched placebo stocking and followed up every 3 months for treatment failure, defined a priori. RESULTS: In study 1, 6 (5.0%) of 120 patients were categorized as treatment failures, a rate similar to placebo-treated study 2 patients (P =.10). In study 2, 0 (0%) of 24 active and 1 (4.3%) of 23 placebo-treated patients were categorized as treatment failures (P =.49). In study 3, 11 (61.1%) of 18 active and 10 (58.8%) of 17 placebo-treated patients were categorized as treatment failures (P>.99). CONCLUSIONS: Most patients do not have PPS 1 year after proximal DVT, and do not require stockings. We failed to show a benefit of stockings in patients with PPS, but the small numbers preclude definitive conclusions.