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

Prevention and control of jet lag symptoms and temporary impairment of cognitive function with Pycnogenol® in healthy individuals and in hypertensives

BACKGROUND

The aim of this registry study was to evaluate the efficacy of Pycnogenol® in controlling signs/symptoms and temporary impairment of cognitive function (COFU) associated with jet lag. Previous flight studies have shown a decrease in the level of jet lag symptoms with Pycnogenol®. The control of jet lag signs/symptoms appeared to be correlated with flight-related microangiopathy and peripheral edema. Pycnogenol® - a standardized extract from the bark of French maritime pine - has significant antiedema, anti-inflammatory and antioxidant properties.

METHODS

A group of subjects flying east in economy class for 10-12 hours used Pycnogenol® 150 mg/day and a similar group without supplementation served as controls. A subgroup of mild hypertensive subjects using a single ACE inhibitor was also included.

RESULTS

One hundred twenty-seven subjects completed the study. Of the participants, 48 were aviation professionals like pilots, flight attendants or air company staff - 24 of them took Pycnogenol® and 24 served as controls. Forty-seven study participants were frequent flyers and non-staff professionals, 25 of which took Pycnogenol® and 22 served as controls. In addition, a group of 32 subjects with mild hypertension was included, 16 took Pycnogenol® and 16 served as controls. No side effects and a good tolerability were observed. The registry groups were comparable for baseline characteristics. Eastbound flights' duration was 11.22±0.4 hours in supplemented subjects and 11.14±0.32 in controls. Dropouts were due to logistical problems. Post flight Visual Analogue Scale (VAS) scores were significantly lower in all Pycnogenol® groups, including hypertensives for all signs and symptoms of jet lag compared to controls, showing prevention and improvement of jet lag symptoms. The duration of any sign/symptom of jet lag with Pycnogenol® intake was significantly shorter (P<0.05) post-flight compared to controls (P<0.05). The number of nights of altered/disturbed sleep was also lower in the Pycnogenol® groups compared to controls. Leg edema was present in almost all subjects with different degrees especially in the hypertensive group. The increase in ankle circumference before and after flight was significantly lower with Pycnogenol® compared to controls (P<0.05). After the flight, average scores of the single COFU tasks were significantly higher in the Pycnogenol® groups compared to controls, showing preserved cognitive function.

CONCLUSIONS

In conclusion, in this registry study Pycnogenol® was effective in preventing jet lag-related symptoms and preserving cognitive functions without tolerability problems. These observations should be tested in a larger group of subjects including complex individuals prone to edema (i.e. diabetics, hypertensive or older patients).

Nattokinase historical sketch on experimental and clinical evidence

Nattokinase (NK) is a protease derived from food used mainly in the Japanese diet that has several properties. The main activity is related to improving fibrinolytic activities. Other activities have been demonstrated in the regulation of blood pressure by the action toward angiotensin proteases and in the antiplatelet activities. NK can be given orally and reaches its maximal concentration after 12 hours. In addition, an antithrombotic activity based on various NK activities has been proposed. First, increased fibrinolytic activity increases thrombus dissolution and/or the formation of atherosclerotic plaques; second, its enhanced antiplatelet action adds to clot dissolution. All activities have been studied in animals and humans in vitro and in vivo. Relevant adverse effects of NK therapy have not been described, however clinical experience is restricted to case series and volunteers and is not based on clinical studies, thus clinical trials are required to confirm.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia–reperfusion (I–R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I–R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.

Efficacy of Functional Foods, Beverages, and Supplements Claiming to Alleviate Air Travel Symptoms: Systematic Review and Meta-Analysis

Airline passengers experience a range of symptoms when travelling on long flights. This review evaluated the efficacy of functional foods, beverages, and supplements claiming to address the effects of air travel for healthy adults. Products were identified in a scoping review of electronic databases, search engines, and grey literature (March to August 2019). A systematic review of the efficacy of product ingredients was conducted using five electronic databases from inception to February 2021. Articles were screened, data extracted, and assessed for risk of bias by two researchers independently. Meta-analysis was performed. Of the 3842 studies identified, 23 met selection criteria: melatonin (n = 10), Pycnogenol (n = 4), various macronutrients (n = 2), caffeine (n = 2), Centella asiatica (n = 1), elderberry (n = 1), Echinacea (n = 1), fluid (n = 1), and Pinokinase (n = 1). Meta-analysis (random effects model) indicated melatonin reduced self-reported jetlag following eastbound (n = 5) and westbound (n = 4) flights: standard mean difference −0.76 (95% CI = −1.06 to −0.45, I2 0%, p < 0.00001) and −0.66 (95% CI = −1.07 to −0.26, I2 45%, p = 0.001), respectively. Pycnogenol also reduced edema scores (n = 3), standard mean −4.09 (95% CI = −6.44 to −1.74), I2 98%, p = 0.0006). Overall, 12 of 183 ingredients contained in 199 products had evidence to support claims.

Direct Oral Anticoagulants and Travel-related Venous Thromboembolism

Travel- related thromboembolism reflects the relationship between venous thromboembolism (VTE) and long-haul flights. Although this condition is rare, it may cause significant morbidity and mortality. Therefore, travelers should be evaluated for the risks for thrombosis. Travel physicians should employ a clinical risk score and select in vestigations, prophylaxis, and treatment that are appropriate for each individual. This review summarizes current VTE clinical risk scores and patient management from various reliable guidelines. We summarized 16 reliable publications for reviewing data. Direct oral anticoagulants (DOACs) are currently the standard treatment for VTE and a prophylactic measure for VTE in orthopedic surgery. Compared with a vitamin K antagonist (VKA), DOACs show better safety and similar efficacy without the need for monitoring, and have fewer food/drug interactions. Inferred from the data on general VTE, DOACs may be used to treat travel-related VTE. Although the data are lacking, DOACs may be used off-label as VTE prophylax is. Before using DOACs, physicians must know the pharmacology of the drugs well and should realize that the availability of antidotes for bleeding complications is limited.

Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis

This report describes a patient's self-substitution of nattokinase for the vitamin K antagonist warfarin after aortic valve replacement with a mechanical prosthesis. Nattokinase is an enzyme derived from a popular fermented soybean preparation in Japan (natto), which has fibrinolytic properties and is gaining popularity in nontraditional health journals and nonmedical health websites as an over-the-counter thrombolytic. After nearly a year of use of nattokinase without warfarin, the patient developed thrombus on the mechanical valve and underwent successful repeat valve replacement. We believe this is the first documented case of nattokinase being used as a substitute for warfarin after valve replacement, and we strongly discourage its use for this purpose.

Postpartum Varicose Veins: Supplementation with Pycnogenol or Elastic Compression-A 12-Month Follow-Up

This open registry aimed to evaluate the clinical evolution of postpartum varicose veins (VVs), in healthy women after the second pregnancy, how these veins regain shape and competence, and possible treatments. The registry included two groups of women: (1) those who used elastic compression stockings, and (2) who used an oral venotonic agent (Pycnogenol, 100 mg/d). A total of 12 evaluation targets were established. Minor symptoms were scored in an analogue scale line. A visual analogue scale line evaluated the overall satisfaction relative to elastic compression or Pycnogenol. Overall 133 women completed the registry evaluation with at least 3 months of follow-up. The resulting two registry groups were comparable. At 3 and 6 months in the Pycnogenol group the number of veins and incompetent sites were lower. At 6 months there were 13.3% of patients with edema in controls versus 3.2% in the Pycnogenol group. Spider veins decreased in Pycnogenol patients. Cramps and other minor symptoms were less common in the Pycnogenol group. In both groups there was a significant improvement at 6 months with better results in the Pycnogenol group. The need for treatment was limited with a decreased need for sclerotherapy, surgery, and conservative treatments in the Pycnogenol group. The overall satisfaction was higher among Pycnogenol patients, and compliance was optimal. Re-evaluation at 12 months indicated that the variations in VVs and spider vein clusters and the associated symptoms did not change. Most remodeling appeared to happen within 6 months after the pregnancy. It was concluded that the use of Pycnogenol improves signs/symptoms of postpartum VVs, and venous function and shape seem to return faster to prepartum, physiological pattern with its use.

Improvements of venous tone with pycnogenol in chronic venous insufficiency: an ex vivo study on venous segments

This study evaluated the stretching and dilatation of venous segments ex vivo in subjects with primary varicose veins in comparison with comparable segments from subjects that used the supplement Pycnogenol (150 mg/d) for 3 months before surgery. Subjects with varicose veins and chronic venous insufficiency voluntarily used Pycnogenol for a period of at least 3 months. The segments of veins removed with surgery (in 30 subjects that had used Pycnogenol and in 10 comparable control subjects that had not used the supplement) were compared with normal, unused vein segments harvested for bypass grafting. The segments were suspended and a weight was attached to the distal part of the veins for 3 minutes and dilated with pressurized water. Digital images were recorded; the veins were measured before and after stretching to evaluate elongation. The manipulation of the vein segment was minimal. Tests were completed within 20 minutes after harvesting the veins. All segments were 4 cm long. The stretching test indicated a significantly higher level of passive elongation in control, varicose segments (2.29; 0.65 mm) in comparison with 1.39; 0.2 mm in vein segments from Pycnogenol-using patients. The dilation test showed an average higher dilation (2.19; 0.3 mm) in control varicose veins in comparison with varicose veins from Pycnogenol-using patients (1.32; 0.7 mm) (p < 0.05). Stretching and dilatation were lower in veins from Pycnogenol-using subjects (p < 0.05). The measurement of destretching and the recovery after dilatation indicated a better tone and recovery of the original size/shape in varicose segments from patients using Pycnogenol. Varicose segments had a more significant persistent dilatation and elongation in comparison with normal vein segments. Pycnogenol seems to decrease passive dilatation and stretching and gives vein walls a greater tonic recovery and elasticity that allows the vein to recover its original shape after dynamic stresses.

Pharmacologic venous thromboembolism prophylaxis after traumatic brain injury: a critical literature review

Despite the frequency and morbidity of venous thromboembolism (VTE) development after traumatic brain injury (TBI), no national standard of care exists to guide TBI caregivers for the use of prophylactic anticoagulation. Fears of iatrogenic propagation of intracranial hemorrhage patterns have led to a dearth of research in this field, and it is only relatively recently that studies dedicated to this question have been performed. These have generally been limited to retrospective and/or observational studies in which patients are classified in a binary fashion as having the presence or absence of intracranial blood. This methodology does not account for the fact that smaller injury patterns stabilize more rapidly, and thus may be able to safely tolerate earlier initiation of prophylactic anticoagulation than larger injury patterns. This review seeks to critically assess the literature on this question by examining the existing evidence on the safety and efficacy of pharmacologic VTE prophylaxis in the setting of elective craniotomy (as this is the closest model available from which to extrapolate) and after TBI. In doing so, we critique studies that approach TBI as a homogenous or a heterogenous study population. Finally, we propose our own theoretical protocol which stratifies patients into low, moderate, and high risk for the likelihood of natural progression of their hemorrhage pattern, and which allows one to tailor a unique VTE prophylaxis regimen to each individual arm.

Prevention of VTE in nonsurgical patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This guideline addressed VTE prevention in hospitalized medical patients, outpatients with cancer, the chronically immobilized, long-distance travelers, and those with asymptomatic thrombophilia.

METHODS

This guideline follows methods described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

For acutely ill hospitalized medical patients at increased risk of thrombosis, we recommend anticoagulant thromboprophylaxis with low-molecular-weight heparin (LMWH), low-dose unfractionated heparin (LDUH) bid, LDUH tid, or fondaparinux (Grade 1B) and suggest against extending the duration of thromboprophylaxis beyond the period of patient immobilization or acute hospital stay (Grade 2B). For acutely ill hospitalized medical patients at low risk of thrombosis, we recommend against the use of pharmacologic prophylaxis or mechanical prophylaxis (Grade 1B). For acutely ill hospitalized medical patients at increased risk of thrombosis who are bleeding or are at high risk for major bleeding, we suggest mechanical thromboprophylaxis with graduated compression stockings (GCS) (Grade 2C) or intermittent pneumatic compression (IPC) (Grade 2C). For critically ill patients, we suggest using LMWH or LDUH thromboprophylaxis (Grade 2C). For critically ill patients who are bleeding or are at high risk for major bleeding, we suggest mechanical thromboprophylaxis with GCS and/or IPC at least until the bleeding risk decreases (Grade 2C). In outpatients with cancer who have no additional risk factors for VTE we suggest against routine prophylaxis with LMWH or LDUH (Grade 2B) and recommend against the prophylactic use of vitamin K antagonists (Grade 1B).

CONCLUSIONS

Decisions regarding prophylaxis in nonsurgical patients should be made after consideration of risk factors for both thrombosis and bleeding, clinical context, and patients' values and preferences.

All I want for coagulation

Evidence-based medicine underpins modern practice of medicine. This paper describes a fictional consultation between Santa Claus and a doctor regarding deep vein thrombosis (DVT) prophylaxis, giving a review of the evidence for DVT prophylaxis in travellers while exposing the difficulty in applying evidence to atypical clinical encounters. Medline and the Cochrane Library were searched, and guidelines reviewed. Keywords used were DVT, thromboembolism, deep vein thrombosis and air travel-related venous thromboembolism. All relevant studies found, have been included in this review, with additional studies identified from the references in these articles. In conclusion, compression stockings, with or without a one-off dose of either aspirin or heparin, are the most evidence-based approaches for prophylaxis in someone with established risk factors for DVT prior to a long-haul flight. Simple exercises should also be encouraged.

[Risk of deep venous thrombosis during an air flight: prevention and counselling at the counter]

Worldwide air traffic reaches about 2.3 billion passengers per year. The increasing number of persons at thrombo-embolic risk, together with potentially severe or fatal complications of deep venous thrombosis, suggests community pharmacists can give basic preventive advice to persons identified as at risk.

[Cardiovascular disease and aircraft transportation: specificities and issues]

With the development of air transport and travel to distant destinations, the number of passengers and elderly passengers on board increases each year. In this population, cardiovascular events are a major concern. Among medical incidents occurring in-flight they are second-ranked (10%) behind gastrointestinal disorders (25%). Their occurrence may involve life-threatening events and require resuscitation, difficult to perform during flight or in a precarious health environment. Coronary heart disease and pulmonary thromboembolic disease are the most serious manifestations. They are the leading cause of hospitalization in a foreign country and sudden cardiac death occurring during or subsequent to the flight. Their occurrence is explained on aircraft by hypoxia, hypobaria and decreased humidity caused by cabin pressurization and upon arrival by a different environmental context (extreme climates, tropical diseases). Moreover, the occurrence of a cardiovascular event during flight can represent for the air carrier a major economic and logistic problem when diversion occurred. Furthermore, the liability of the practitioner passenger could be involved according to airlines or to the country in which the aircraft is registered. In this context, cardiovascular events during aircraft transportation can be easily prevented by identifying high risk patients, respect of cardiovascular indications to travel, the implementation of simple preventive measures and optimization of medical equipment in commercial flights.

Traveller's thrombosis: airlines still not giving passengers the WRIGHT advice!

INTRODUCTION

This study has examined the impact of the World Health Organization's Research into Global Hazards of Travel (WRIGHT) Project's phase 1 report on the information given by airlines to their passengers regarding traveller's thrombosis.

METHODS

Official websites of all airlines flying from Heathrow (UK) and John F Kennedy (USA) were located through links on the websites of these two busy international airports. In June 2007, each site was scrutinized by three independent researchers to identify if traveller's thrombosis and its risk factors were discussed and what methods of prevention were advised. This exercise was repeated a year after the publication of the WRIGHT report.

RESULTS

One hundred and nineteen international airlines were listed in 2007 (12 were excluded from analysis). A quarter (27/107) of airlines warned of the risk of traveller's thrombosis. A year later, five airlines were no longer operational and there had been no increase in the discussion of traveller's thrombosis (23/102). Additional risk factors discussed in June 2007 versus September 2008: previous venous thromboembolism (16%, 15%); thrombophilia (14%, 15%); family history (11%, 9%); malignancy (12%, 14%); recent surgery (19%, 16%); pregnancy (17%, 16%) and obesity (11%, 12%). Prophylaxis advice given in June 2007 versus September 2008: in-flight exercise (34%, 42%); Hydration (30%, 34%); medical consultation prior to flying (20%, 18%); graduated compression stockings (13%, 12%); aspirin (<1%, <1%) and heparin (5%, 7%).

CONCLUSIONS

The majority of world airlines continue to fail to warn of the risk of traveller's thrombosis or offer appropriate advice. Alerting passengers at risk gives them an opportunity to seek medical advice before flying.

Pycnogenol: a blend of procyanidins with multifaceted therapeutic applications?

Great interest is currently centred on the biologic activities of pycnogenol a standardized plant extract obtained from the bark of the French maritime pine Pinus pinaster (formerly known as Pinus maritima), Aiton, subspecies Atlantica des Villar (Pycnogenol, Horphag Research Ltd., UK, Geneve, Switzerland), which grows in the coastal southwest France. The quality of this extract is specified in the United States Pharmacopeia (USP 28). Between 65% and 75% of Pycnogenol are procyanidins comprising of catechin and epicatechin subunits with varying chain lengths. Other constituents are polyphenolic monomers, phenolic or cinnamic acids and their glycosides. As many studies indicate, pycnogenol components are highly bioavailable. Uniquely, pycnogenol displays greater biologic effects as a mixture than its purified components do individually indicating that the components interact synergistically. Pycnogenol is now utilized throughout the world as a nutritional supplement and as a phytochemical remedy for various diseases ranging from chronic inflammation to circulatory dysfunction, including several impaired psycho-physiological functions. Owing to the basic chemical structure of its components, the most obvious feature of pycnogenol is its strong antioxidant activity. In fact, phenolic acids, polyphenols, and in particular flavonoids, are composed of one (or more) aromatic rings bearing one or more hydroxyl groups and are therefore potentially able to quench free radicals by forming resonance-stabilized phenoxyl radicals. In this review, emphasizing the molecular, cellular, and functional bases of therapy, data appearing in the peer-reviewed literature and focussing the main therapeutic applications of pycnogenol will be summarized and critically evaluated.

Some chronobiological and physiological problems associated with long-distance journeys

Long-distance travel is becoming increasingly common. Whatever the means of transport, any long journey will be associated with "travel fatigue". The symptoms associated with this phenomenon result from a changed routine (particularly sleep lost and meals) and the general disruption caused by travel. Planning any trip well in advance will minimise many of these problems, but some factors are less easy to guard against. These problems include sitting in cramped and uncomfortable conditions and, with flights, the hypoxic environment in the cabin. After arrival at the destination in another country, there can be problems coping with the local language, alterations in food and different customs. If the flight has crossed the equator, then there is likely to be a change in season and natural lighting and, if it has crossed several time zones, there will also be the problem of "jet lag", caused by a transient desynchrony between the "body clock" and the new local time. Moreover, the new environment might differ from the place of departure with regard to ambient temperature and humidity, altitude, natural lighting (including ultraviolet radiation) and pollution. The traveller needs to be aware of these changes before setting off, so that appropriate preparations (clothing, for example) can be made.

The Tromped: A Solution for Flight-Related Deep Vein Thrombosis?

Flight-related deep vein thrombosis (DVT) is well recognized. Reduced venous return occurs during immobility. This alteration in venous hemodynamics may contribute to DVT development. A prototype design of an in-flight exercise device to stimulate ambulatory bloodflow while seated has been developed, consisting of a foot pedal attached to a base by a hinge mechanism. Four devices of differing resistance were evaluated. Calf muscle pump function was assessed by air plethysmography in 10 healthy volunteers. Ejection volume fraction and RVF were determined in the standing position (control values) and were compared with those achieved by depression of the 4 devices while seated. Similar EVF and RVF values were achieved by the control and 2 of the devices. Plantar flexion against a predetermined resistance can effectively activate the calf muscle pump while seated and may reduce the incidence of flight-related DVT.

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.

Dietary supplements, herbs and oral anticoagulants: the nature of the evidence

In the US, the use of dietary supplements, including vitamins, minerals, amino acids, and herbal products, is extensive. Nonetheless, the majority of patients report that they have little information about the risks, benefits, and adverse effects of medicines, or about their potential interactions with prescription drugs. Patients taking warfarin are at particular risk of interactions with dietary supplements, yet approximately 30% use herbal or natural product supplements on a regular basis. No current governmental regulations or voluntary programs address dietary supplement interactions with prescription drugs. Case reports represent the majority of the evidence surrounding drug interactions between warfarin and dietary supplements. Those of the highest quality include, as an assessment of causality, a modification of the recently published Drug Interaction Probability Scale. Despite positive case reports, formal drug interaction studies are often negative, suggesting that numerous patient-specific influences other than the suspected interaction alone may be responsible for a particular observation. The cranberry-juice/warfarin interaction is a recent example of such a discrepancy. Healthcare providers can play an active role in improving quantity and the quality of case reports of interactions involving warfarin and dietary supplements. A registry of anticoagulant interactions with dietary supplements has been proposed, and is currently being developed through Clotcare Online Resource (http://www.clotcare.com). The goal of this registry is to obtain high quality case-based evidence of drug interactions between anticoagulants and dietary supplements, to define these interactions based on clinical and monitoring outcomes, and to analyze likelihood of causation using a modification of the Drug Interaction Probability Scale.

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.

Toward a core nutraceutical program for cancer management

As previously suggested, it may be feasible to impede tumorevoked angiogenesis with a nutraceutical program composed of glycine, fish oil, epigallocatechin-3-gallate, selenium, and silymarin, complemented by a low-fat vegan diet, exercise training, and, if feasible, a salicylate and the drug tetrathiomolybdate. It is now proposed that the scope of this program be expanded to address additional common needs of cancer patients: blocking the process of metastasis; boosting the cytotoxic capacity of innate immune defenses (natural killer [NK] cells); preventing cachexia, thromboembolism, and tumor-induced osteolysis; and maintaining optimal micronutrient status. Modified citrus pectin, a galectin-3 antagonist, has impressive antimetastatic potential. Mushroombeta-glucans and probiotic lactobacilli can amplify NK activity via stimulatory effects on macrophages. Selenium, beta-carotene, and glutamine can also increase the number and/or cytotoxic activity of NK cells. Cachectic loss of muscle mass can be opposed by fish oil, glutamine, and beta-hydroxy-beta-methylbutyrate. Fish oil, policosanol, and vitamin D may have potential for control of osteolysis. High-dose aspirin or salicylates, by preventing NF-B activation, can be expected to aid prevention of metastasis and cachexia while down-regulating osteolysis, but their impacts on innate immune defenses will not be entirely favorable. A nutritional insurance formula crafted for the special needs of cancer patients can be included in this regimen. To minimize patient inconvenience, this complex core nutraceutical program could be configured as an oil product, a powder, and a capsule product, with the nutritional insurance formula provided in tablets. It would be of interest to test this program in nude mouse xenograft models.

Cramps and muscular pain: prevention with pycnogenol in normal subjects, venous patients, athletes, claudicants and in diabetic microangiopathy

The aim of this study was to assess the preventive action of Pycnogenol (Horphag Research Ltd, UK) on cramps and muscular pain in different groups of subjects and patients. The study included a 5-week observation period (4 weeks treatment and one follow-up week after the suspension of treatment) to evaluate the efficacy of Pycnogenol after its withdrawal. Four 50 mg capsules (total dose 200 mg/day) were prescribed with suggestion to drink at least 1.5 liters of water every day. In the first part of the study 66 healthy subjects completed a 5-week follow-up period. The difference between number of cramps attacks recorded within the 2 weeks before inclusion and the number of episodes during the fourth (p <0.05) and fifth (p <0.05) week were statistically significant. In normal subjects the average number of episodes was reduced from 4.8 (1.2) events per week to 1.3 (1.1) at 4 weeks (p <0.05). In venous patients the decrease in events was from 6.3 (1.1) to 2.6 (0.4) per week (p <0.05). In athletes the number of episodes decreased from 8.6 (2) to 2.4 (0.5) (p <0.05). The decrease was still present at 5 weeks in the 3 groups, to levels significantly lower than inclusion values (p <0.05). In the second part of the study, patients with intermittent claudication and diabetic microangiopathy were evaluated and treated (4 weeks). The groups treated with Pycnogenol and the control, placebo groups were comparable. There was a significant decrease in the number of cramps episodes (p <0.05) and in the score concerning muscular pain (p <0.05) in claudicants and diabetics. No significant effects were observed in the placebo groups. In conclusion, cramps and muscular pain, common in these 2 types of patients, were decreased by the use of Pycnogenol. Globally, these results suggest that the use of Pycnogenol prevents cramps, muscular pain at rest, and pain after/during exercise in normals, in athletes prone to cramps, in patients with venous disease, in claudicants, and in diabetics with microangiopathy. The difference is statistically significant considering objective observations (cramps episodes) and evaluating more subjective aspects (score). This indicates that Pycnogenol is effective in reducing pain and cramps during retraining and rehabilitation increasing its efficiency. In starting any physical rehabilitation program, particularly in vascular subjects, the limitation in mobility associated with muscular pain and with cramps tends to be relevant, and controlling these symptoms is useful to speed up the retraining process.

Venous Thromboembolic Complications Following Air Travel: What's the Quantitative Risk? A Literature Review

OBJECTIVES

To quantify the risk of venous thromboembolism (VTE) following air travel and assess methods of prevention.

DESIGN

Review of literature.

METHODS

We reviewed Pubmed, Medline, Embase and Cochrane Databases for studies that have assessed the risk of VTE associated with air travel.

RESULTS

There is an association of VTE with air travel with pooled odds ratio of 1.59 (confidence interval 1.04-2.43) from three case control studies and relative risk of 2.93 (confidence interval 1.5-5.58) from two controlled cohort studies. The incidence of symptomatic pulmonary embolism (PE) is extremely low but there is substantial increase when the distance travelled is more than 5,000 miles (1.5 PE per million passengers) or time of flight is more than 8h duration (2.57 PE per million passengers). The quantitative risk of lower limb venous thrombosis in high-risk subjects is 5% per flight and 1.6% per flight for low risk subjects following long haul flights. All six randomised trials to test the below knee compression stockings with ankle pressures of 14-30 mmHg have shown reduction in lower limb venous thrombosis.

CONCLUSION

VTE is more common in those with additional risk factors when the risk is about 5% per air travel for long haul flights. Class I or II below knee compression stockings are effective in the prevention of lower limb venous thrombosis.

Air travel and thrombosis

The current literature suggests a weak association between long-distance travel and the development of asymptomatic venous thromboembolism (VTE). Most of the data available relate to air travel and suggest that the risk is largely confined to asymptomatic calf vein thrombosis in passengers with additional risk factors for VTE, travelling for more than 8 h. The risk of both symptomatic and fatal pulmonary embolism (PE) is very small. The causal role of travel-related factors (e.g. stasis, dehydration, cramped seats and hypobaric hypoxia) is not yet proved but, given the plausible risk-free benefit, all passengers should be advised to maintain adequate hydration and exercise. There is currently no evidence for 'routine' thromboprophylaxis using stockings or drugs. In passengers with additional risk factors for VTE, thromboprophylaxis in the form of below-knee graduated compression stockings (providing 15-30 mmHg at the ankle) and/or prophylactic dose low-molecular-weight heparin may be considered. The evidence does not support the use of aspirin, which is associated with a significant rate of adverse gastrointestinal effects.

Travel and thrombosis

The available evidence suggests an association between long distance travel and the development of venous thromboembolism. The main problem for travellers and physicians is the interpretation of the evidence and its translation into appropriate advice on the risk and the prevention of thrombosis. Most available data relate to air travel. Thrombosis risk is greater following journeys of more than 8 h and those at greatest risk are travellers with a history of venous thromboembolism or risk factors. Based on the best evidence available the risk of symptomatic venous thromboembolism after flights of more than 12 h is 0.5%. It is likely that stasis plays a major role in the aetiology of travel related thrombosis. The evidence for hypobaric hypoxia induced coagulation activation requires confirmation. There is evidence that compression stockings and low molecular weight heparin prevent asymptomatic deep vein thrombosis (DVT) but clinical DVT has been observed in long distance flyers in spite of prophylaxis with aspirin and stockings.

Long-haul air travel before major surgery: a prescription for thromboembolism?

OBJECTIVE

To investigate the Incidence of postoperative venous thromboembolism (VTE) in patients who had flown long distances before major surgery.

PATIENTS AND METHODS

Using the Mayo Clinic computerized patient database, we Identified patients who had flown more than 5000 km before major surgery (travelers) and had experienced an episode of clinically significant VTE within 28 days after surgery. Individual medical records were reviewed for the diagnosis of VTE, pertinent risk factors, and outcome. We compared the Incidence of VTE in travelers to the incidence of VTE in patients from North America (nontravelers) undergoing similar surgical procedures.

RESULTS

Eleven patients met our criteria for long-haul air travel and clinically significant VTE within 28 days after surgery. Compared with nontravelers undergoing similar surgical procedures, long-haul travelers had a higher Incidence of VTE (4.9% vs 0.15%; P < .001). Compared with nontravelers who developed VTE, travelers were younger (P = .006), developed VTE earlier in the postoperative course (P = .01), had higher American Society of Anesthesiologists physical status classification (P = .02), and had higher prevalence of smoking (P = .007). Of the 11 travelers with VTE, 10 were of Middle Eastern origin.

CONCLUSION

Prolonged air travel before major surgery significantly increases the risk of perioperative VTE. Such patients should receive more Intensive VTE prophylactic measures during the flight and throughout the perioperative period.

[The risk of thromboembolism in airline passengers]

Long carrier flights favor thromboembolism. The risk is well known to the general public but is probably really very low. The risk is however pertinent due to the volume of air travel in the world. Sitting in the same position for a long time induced venous stasis which is the principal factor favoring thrombosis in travelers, irrespective of the means of transportation. Long carrier flights also expose passengers to specific factors related to air travel: coagulation disorders and alterations of the endothelium related to hypobarism, hypoxia and low hygrometry in the cabin. Presence of pathogenic thrombophilia is not a constant factor. The prevention of venous thrombosis in air travelers calls upon simple measures: abundant hydration, avoiding use of alcohol and tobacco, walking and dorsal flexion of the feet. The only preventive option with proven efficacy is the use of elastic contention which reduces the risk of thromboembolic events. There is no consensus concerning the use of drugs proposed by certain authors; prudence should be the rule. All passengers should become aware of the risk of thromboembolism related to sitting in the same position for a long time.

Fatal Acute Pulmonary Embolism in a Patient with Pelvic Lipomatosis After Surgery Performed After Transatlantic Airplane Travel

We describe a case of a 37-yr-old patient who traveled from Europe to the United States and succumbed to a massive pulmonary embolism 6 days after elective pelvic surgery despite routine postoperative thrombotic prophylaxis. In retrospect, he was likely to have developed a deep venous thrombosis during the transatlantic trip to our hospital. Anesthesiologists and other physicians involved in perioperative management need to be aware of the prevalence of venous thromboembolism in patients with a history of recent prolonged air travel. This is particularly true in tertiary referral centers, where patients with rare diseases may have a major surgical intervention within days of prolonged air travel.

Airline Chair-Rest Deconditioning

Air passenger miles will likely double by year 2020. The altered and restrictive environment in an airliner cabin can influence haematological homeostasis in passengers and crew. Flight-related deep venous thromboemboli (DVT) have been associated with at least 577 deaths on 42 of 120 airlines from 1977 to 1984 (25 deaths/million departures), whereas many such cases go unreported. However, there are four major factors that could influence formation of possible flight-induced DVT: sleeping accommodations (via sitting immobilisation); travellers' medical history (via tissue injury); cabin environmental factors (via lower partial pressure of oxygen and lower relative humidity); and the more encompassing chair-rest deconditioning (C-RD) syndrome. There is ample evidence that recent injury and surgery (especially in deconditioned hospitalised patients) facilitate thrombophlebitis and formation of DVT that may be exacerbated by the immobilisation of prolonged air travel. In the healthy flying population, immobilisation factors associated with prolonged (>5 hours) C-RD such as total body dehydration, hypovolaemia and increased blood viscosity, and reduced venous blood flow (pooling) in the legs may facilitate formation of DVT. However, data from at least four case-controlled epidemiological studies did not confirm a direct causative relationship between air travel and DVT, but factors such as a history of vascular thromboemboli, venous insufficiency, chronic heart failure, obesity, immobile standing position, more than three pregnancies, infectious disease, long-distance travel, muscular trauma and violent physical effort were significantly more frequent in DVT patients than in controls. Thus, there is no clear, direct evidence yet that prolonged sitting in airliner seats, or prolonged experimental chair-rest or bed-rest deconditioning treatments cause DVT in healthy people.