Ngoh Chin Liew

Postoperative venous thromboembolism in Asia: a critical appraisal of its incidence.

OBJECTIVES Venous thromboembolism (VTE) has historically been perceived to be a rare disorder in Asia. However, new evidence has emerged recently that contradicts this perception. The question of routine VTE prophylaxis has been hotly debated in Asia due to disagreement on its incidence. We reviewed and analysed studies on postoperative VTE in Asian patients to determine if the condition was indeed rare and if the routine prophylactic measures as recommended by internationally accepted guidelines should be adopted in Asia. METHODS A review of published reports, from 1966 to December 2002, on deep vein thrombosis (DVT) and pulmonary embolism (PE) in the Asian population was made. A literature search of studies published in English was conducted via a detailed MEDLINE search. Studies had to attain a minimum inclusion and quality criteria to be accepted for the review, including the diagnostic modality used for the diagnosis of VTE. The appraisal was carried out independently and accepted by at least two of the three authors. The study population was classified into orthopaedic and general surgical/colorectal groups. RESULTS Twelve orthopaedic publications reviewed revealed an incidence of postoperative DVT of 10% to 63%. Six general and colorectal surgical publications reported an incidence of DVT ranging from 3% to 28%. The incidence was slightly lower than the reported incidence of 40% to 80% following orthopaedic surgery and 28% to 44% following general surgical operations in studies reporting on Caucasian populations. CONCLUSION While there is a wide variation in the incidence of DVT and VTE as reported in the Asian population, these diseases are by no means rare. The wide variation could be due to the study designs, heterogeneity of the procedures performed and the application of different diagnostic criteria. Results based on prospective studies with objective diagnostic criteria confirm the incidence of VTE as common. Routine chemoprophylaxis must be seriously considered in high-risk patients.

Pathogenesis and Management of Buerger’s Disease

Buerger’s disease or thromboangiitis obliterans causes pain, ulceration, or gangrene in the lower or upper extremity. It is associated with chronic cigarette smoking and is believed to be an immune mediated vasculitis. The pathogenesis is still unknown but recent postulate of its association with odontal bacteria has generated much renewed interest. Despite its recognition more than a century ago, little progress has been made in its treatment. Until the pathogenesis is elucidated, abstinence from cigarette is the only effective therapy.

Training in dialysis access - charting future success

Purpose Medical education and training in dialysis access skills remains complex and inadequate as learners come from diverse backgrounds and from various specialties so that appropriate training is limited. As a result, a system of progressive education including live lectures, and hands on training has emerged, but there is controversy as to what constitutes the best educational model. Methods Presently there is no recognized or structured training in vascular access during residency or fellowships. Here we present a model of dialysis access training for beginner to advanced surgeons. Results A structured hands-on and didactic surgery training certification course consisting of a one week curriculum with 49 hours of ACCME credit hours has been in effect for one year. The learning impact and the performance outcome are high but with limited attendance capacity. Pre- and post- training test results attest to training effectiveness. To increase access, an off-site training curriculum has been initiated, entailing 1-2 days (8-15 credit hours) consisting of didactic lectures and surgical training. This teaching module has moderate learning impact for 50-100 attendees. Finally, a tiered, web-based training curriculum (10 ACCME credit hours) can accommodate an unlimited number of learners, but has a lower skills learning impact. Conclusions The future dialysis access training must also accommodate learners with diverse individual backgrounds, and different levels of professional (skill) development. To be effective and accessible, a variety of educational system, for example on site or web based is needed. Collaborative initiatives for global dialysis access training are currently underway.

Previous radial artery harvest for coronary artery bypass graft does not impede ipsilateral proximal vascular access construction.

constructed. Theoretically, construction of this arteriovenous fistula is similar to performing an Allen’s test and found that it is positive. Whether it translates to potential ischemia of the hand when fistula is constructed is still debatable. Nevertheless, literature recommends Allen’s test before any vascular access surgery (2). To our knowledge, there are no reports of BBF construction after RAG harvest but one of DHIS after BCF in a patient with previous RAG harvesting for CABG (1). The conclusion in this case report is that the brachial and ulnar arteries are compromised by atherosclerosis and could not adapt to the increased flow into the low resistance cephalic vein after a BCF, leading to DHIS (1). On the other hand, not all arteries are affected equally by atherosclerosis. We have encountered pristine radial and ulnar arteries despite severely diseased coronaries, in the course of coronary arteriogram through a radial artery approach. The same argument supports why radial artery harvesting is commonly performed even in diabetics undergoing CABG. While atherosclerosis in diabetic patients is generally systemic, a non-stenosed and non-calcified artery should have the potential to adapt to shear stress and to enlarge many times its size, even in diabetics. Moreover, Allen’s test is frequently performed before RAG harvesting and arguably DOI: 10.5301/jva.5000470

Appendicitis despite previous appendicectomy

When a patient presenting with right iliac fossa pain, tenderness and guarding has had a previous appendicectomy, the possibility of appendicitis is frequently dismissed. The clinical features will usually be explained by other diagnoses or resolve without any untoward consequences. Two patients with a history of previous appendicetomy and the scars of a right iliac fossa appendicectomy incisions were found at laparotomy to have acute appendicitis.

Venous Thromboembolism Prophylaxis in High-Risk General Surgery in Asia

To the Editor, We read with great interest the article by Yeo et al. [1]. The authors, in their systematic review of venous thromboembolism (VTE) incidence in Asian patients, concluded that VTE risk in high-risk general surgical patients is generally low and that routine pharmacological prophylaxis for these patients cannot be recommended [1]. We have published a similar paper appraising the incidence of perioperative VTE in Asian general surgical and orthopedic patients in 2003 [2]. While there are good prospective studies to estimate VTE incidence following proximal hip fracture surgery, total hip, and knee replacements, there are inadequate quality papers to conclude on the incidence of VTE in general surgery in Asia. The authors have reviewed 14 published articles based on their criteria of Asian studies and major gastrointestinal or other general surgical operations. The primary outcome was deep vein thrombosis (DVT) or pulmonary embolism (PE) and secondary outcomes were mortality and complications of VTE or thromboprophylaxis. We noted that the articles reviewed were mainly observational studies on symptomatic VTE, comprising heterogeneous sample size, variable surgical procedures (including open and laparoscopic surgery), and with different diagnostic modalities and lengths of follow-up. There was a wide variation in the incidences between the prospective and retrospective studies. The median incidences quoted in the retrospective studies for all DVT, above knee DVT, all PE, and fatal PE were 0.06, 0.0, 0.18, and 0.0 % whereas in prospective studies, they were 24, 2.1, 0.18, and 0 %, respectively [1]. From these, the authors estimated the overall incidence of all DVT as only 1.4 % when its incidence in prospective studies ranged from 2.1 to 42 %. While overall incidence of fatal PE was estimated as 0 %, they failed to elaborate on the deaths due to PE in both retrospective and interventional studies. There were 2 fatal PE in one of the retrospective colorectal cancer study [1], 2 in 215 control patients by Dar et al. [3], and 1 in three patients with PE in the control group of 169 by Ho et al. [4]. The authors suggest that using their estimated symptomatic VTE risk of 1–2 % in high-risk Asian general surgical patients, they fit into low-risk group of the 9th ACCP guidelines for risk stratification. The risk stratification in the ACCP is mainly based on a retrospective VTE risk model study on a population of patients in Michigan [5]. In our opinion, the authors should be cautious in drawing such conclusion, extrapolating median incidence from a small number of studies with heterogeneous population and comparing it with the risk model study. Nevertheless, we agree that incidence of post-operative VTE is perhaps slightly lower in Asia but the literature on Asian VTE incidence is still lacking. We should not forget that, from the international data, there is a significant proportion of asymptomatic PE in every fatal PE. Until there is robust evidence in Asia, we recommend adherence to thromboprophylaxis guidelines in high-risk general surgical patients.

Healing of venous ulcers secondary to an ankle arteriovenous fistula

Venous ulcer as a complication of ankle arteriovenous fistula for hemodialysis is rarely reported. It poses a challenge between ulcer healing and fistula preservation. We report our experience in the management of venous ulcers secondary to an ankle arteriovenous fistula in a hemodialysis patient.