Travellers' thrombosis and economy class syndrome: incidence, aetiology and prevention

Comprehensive Quality Control of the Regenerative Therapy Using Platelet Concentrates: The Current Situation and Prospects in Japan

Platelet concentrates (PCs), represented by platelet-rich plasma (PRP), have been widely applied in the fields of regenerative and aesthetic therapies. PCs' mechanisms of action, however, are too complicated, and it is not easy to present the whole picture; besides, clinical outcomes are hardly reproducible in many cases. Therefore, several medically advanced countries seemingly intend to regulate PC therapies weakly or strictly because of the increasing popularity. Japan established laws and regulations for PC therapy in the "Act on the Safety of Regenerative Medicine" along with the "Pharmaceuticals, Medical Devices and Other Therapeutic Products Act" in 2014, which, to our knowledge, represent the strictest regulatory framework for production and therapeutic use of PCs in the world. According to these laws and regulations, PCs produced for topical use should be prepared as cell-based medicinal products, essentially as should stem cells, in accordance with their registered ("licensed" under actual conditions) standard operating procedures. Nonetheless, criteria for their quality are not standardized. In this review, we discuss the quality of PC preparations by focusing on the basic concept and regulatory framework of regenerative medicine in Japan. Within the new framework, PC therapy is regulated by a specific notification and registration system, as is stem cell therapy. In comparison with the latter, however, risk factors that hamper successful PC therapy are much fewer. Via appropriate evaluation of patients' conditions and whole-blood samples by simple and sensitive but not yet fully standardized assays, it is theoretically possible that PC quality will be controlled nearly completely. In addition to or instead of standardization of preparation protocols, standardization of preoperative examination of individual PC preparations is an urgent task for improving and guaranteeing the safety and efficacy of PC therapy.

Successful surgical treatment for a thrombus straddling a patent foramen ovale: a case report

Paradoxical embolism (PDE) occurs after embolic material passes from the venous to the arterial circulation through a right-to-left shunt, which is frequently a patent foramen ovale (PFO). We describe the case of a patient with deep venous thrombosis and an intracardiac thrombus straddling a PFO and who was successfully treated with an emergency surgery.

Three cases of pulmonary thromboembolism and extensive prayer (invocation) activity as a new possible risk factor

Pulmonary thromboembolism (PTE) is caused when thrombi are detached from the deep vein of the lower leg. In the field of forensic medicine, it is a well-known cause of sudden death. It has been reported that risk factors for PTE include surgery, trauma, extensive bed rest, and malignant neoplasm, among others; in addition, long-haul air travel is associated with a slightly increased risk for PTE, though such cases are rare. Recently, PTE had been reported in association with different conditions, such as ethrombosis, seated immobility thromboembolism, driving for long periods, and after traveling. The authors performed autopsies on 3 patients who died suddenly after 3 to 4 days of prayer in a prayer center or hermitage. It was confirmed that all deaths were caused by thrombi that had developed in the deep vein, obstructing the pulmonary artery. It was concluded that during repeated praying activities over an extensive time period, the kneeling position might have caused PTE. It is also possible that dehydration due to fasting may affect the formation of thrombi. According to the literature, PTE cases developed in association with prayer activity and position have not been reported to date, and so PTE caused by prayer activity is thought to be a new type of PTE developed in association with a certain life style. Therefore, people should be advised that a position involving a long period of immobilization, including long periods of prayer, could raise the risk of PTE. In addition, social policies to prevent the development of this kind of PTE are needed.

Impact of earthquakes on risk for pulmonary embolism

Physical and psychological stress induced by catastrophic events such as earthquakes can lead to sudden death, acute coronary syndrome, stroke, and other cardiovascular diseases. We investigated the impact of the earthquake that occurred in Niigata, Japan, on pulmonary embolism. Pulmonary embolism increased to 9 cases in the 4 weeks after the earthquake, compared to 1 case in the 4 weeks before the earthquake, 2 cases in the corresponding 8 weeks in 2003, and 1 case in 2002. The first case occurred two days after the initial earthquake and new cases were reported for 27 days thereafter. Six of 9 patients (67%) took refuge in their automobiles before the onset of pulmonary embolism. Sudden death also increased after the earthquake and 7 of 22 cases (32%) spend night(s) in automobile. In conclusion, pulmonary embolism should be attended after disasters and prolonged immobilization in automobiles may increase risk of pulmonary embolism and sudden death.

Risk factors, health risks, and risk management for aircraft personnel and frequent flyers

Health risks associated with long periods of time in flight are of concern to astronauts, crew members, and passengers. Many epidemiological studies showed that occupational and frequent flyers may be susceptible to ocular, cardiovascular, neurological, pulmonary, gastrointestinal, sensory, immunological, physiological, and even developmental disorders. In addition, the incidences of cancer and food poisoning are expected to be higher in such individuals. This article reviews health risks and risk factors associated with air travel, and discusses risk management strategies. To reduce adverse health risks, risk factors such as radiation, infection, stress, temperature, pressure, and circadian rhythm need to be avoided or reduced to levels that are as low as technologically achievable to protect flight personnel and passengers.

Increased frequency of cardioembolism and patent foramen ovale in patients with stroke and a positive travel history suggesting economy class stroke syndrome

OBJECTIVE

To investigate the frequency of acute stroke in patients with a recent travel history and to analyse risk factors, stroke patterns and presence of a patent foramen ovale (PFO) in this patient group.

DESIGN

One-year prospective observational study.

SETTING

Single-centre study.

METHODS

Enrolling all patients presenting with a first cerebral ischaemia and complementing the usual history with a standardised travel history.

RESULTS

Of 338 patients with acute stroke, 42 had a positive travel history (PTH) (12.4%). Patients with a PTH were significantly younger (56.6 (SD 13) years) than patients (66.9 (13.2) years, p = 0.0001) with a negative travel history (NTH). Frequency of PFO in the PTH group (13; 44.8%) was significantly higher than in the NTH group (7; 10.8%) (p = 0.0001), even after patients were dichotomised into two age groups (younger and older than median of all

PATIENTS

31% v 6.1%, p = 0.007 and 13.8% v 4.6%, p = 0.022, respectively). PTH patients had fewer stroke risk factors (2.2 (1.4) v 3.3 (1.6), p = 0.0001) and a different risk profile with a lower frequency of diabetes (11.9% v 31.4%, p = 0.009), hypertension (52.4% v 78.7%, p = 0.0001), atrial fibrillation (7.1% v 22%, p = 0.025) and others (16.7% v 38.9%, p = 0.005). In contrast, PTH patients had significantly more cardioembolic (35.7% v 19.3%, p = 0.023) and cryptogenic strokes (50% v 19.9%, p = 0.0001) and more often ischaemia in the territory of the posterior cerebral artery (29.6% v 6.3%, p = 0.0001).

CONCLUSIONS

The finding that more PTH patients had a PFO and a cardioembolic stroke pattern but that fewer had other typical stroke risk factors led to the hypothesis that PFO is a risk factor for economy class stroke syndrome.

Graduated compression stockings as prophylaxis for flight-related venous thrombosis: systematic literature review

AIM

This paper reports a systematic review whose objective was to evaluate the effectiveness of graduated compression stockings as prophylaxis for flight-related venous thrombosis, including deep vein thrombosis and superficial venous thrombosis, after air travel in the general population.

BACKGROUND

Despite the extended history of the use of graduated compression stockings, their application to prevent flight-related thrombosis was not explored until flight-related thrombosis was perceived as a preventable illness. Even now, their effectiveness in preventing flight-related thrombosis remains unresolved.

METHODS

Generic terms including stocking/s, sock/s, or hosiery/hosieries were used to search a variety of electronic databases. Based on the selection criteria, decisions regarding inclusion and exclusion of primary studies were made. Using a meta-analysis software program, relative risk for the incidence of deep vein thrombosis, superficial venous thrombosis, and intention-to-treat analysis was calculated.

RESULTS

A total of nine randomized controlled trials were included. In the treatment group, two of 1237 participants developed deep vein thrombosis in comparison with 46 of 1245 in the control group. The weighted relative risk for deep vein thrombosis was 0.08, with fixed 95% confidence interval 0.03-0.23. In the treatment group, four of 826 participants developed superficial venous thrombosis in comparison with seven of 823 in the control group. The weighted relative risk for superficial venous thrombosis was 0.67. with fixed 95% confidence interval 0.24-1.87 (non-significant difference). Using intention-to-treat analysis, the risk for participants in the treatment group was 0.53 times as great as that for those in the control group.

CONCLUSIONS

This review demonstrates the effectiveness of medium compression pressure, below-knee graduated compression stockings in preventing flight-related deep vein thrombosis but not superficial venous thrombosis in low-medium- or high-risk participants.

Pulmonary Thromboembolism Associated With Air Travel in Japan

BACKGROUND

A link between venous thromboembolism (VTE) and air travel has been recently discussed, so the present study aimed to clarify the characteristics of acute pulmonary thromboembolism (PTE) associated with air travel in Japan.

METHODS AND RESULTS

The study group comprised 36 patients with acute PTE associated with air travel. Patients' characteristics, clinical risk factors for VTE and coagulation abnormalities were investigated, and compared with a group of PTE not associated with travel. Of the 36 cases, 30 cases were female, 34 were over 40 years of age and all had flown more than 6 h. Two-thirds of all cases did not leave their seats during the flight. Of the patients, 44% had no clinical risk factors for VTE or coagulation abnormalities. Idiopathic PTE (ie, PTE without clinical risk factors or coagulation abnormalities) was significantly more common in the air travel group.

CONCLUSION

Acute PTE associated with air travel in Japan is common in elderly women and may occur without any clinical risk factors for VTE or coagulation abnormalities. Remaining seated throughout the flight increases the risk.