Microcirculation Research for Microsurgeons: Basic Concepts and Potential Applications

The primary purpose of this review is to introduce the techniques of modern microcirculation research to reconstructive microsurgeons and trauma surgeons. When applied to clinically relevant situations, these techniques are powerful tools to elucidate the mechanisms regulating success or failure of a reconstructive procedure. Several phenomena at the microcirculatory level can have significant influence on the outcome of free flaps or replants. Most importantly these are ischemia/reperfusion injury, problems with wound healing and failure of downstream microcirculation due to thrombosis at the vascular anastomosis. Traditional research methods to assess free flap or replant failure utilize patency of the repaired vessel as the principal parameter. This all-or-nothing measurement provides little information about the dynamic mechanisms regulating thrombosis and microcirculation in general. Modern microcirculation research techniques, in contrast, permit direct visualization with qualitative and quantitative analysis of microcirculation in vivo. Applying these modern research techniques in model systems that simulate clinical reconstructive microsurgery has the potential to expand our understanding of the relevance of blood flow and its alterations to clinicals outcomes. To enable such an understanding, this review focuses on elucidating the basic nomenclature used in microcirculation research in context of microvascular problems clinically encountered by reconstructive and trauma surgeons.     

T regulatory cells and transplantation tolerance

Despite the development of successful immunosuppression protocols and tremendous improvement in short-term graft survival rates, the problem of chronic graft loss remains the bane of clinical transplantation. The induction and maintenance of transplantation tolerance is the “Holy Grail” of transplantation.The recent identification and characterization of regulatory T cells has opened up exciting opportunities for tolerance induction, immunotherapy, and immunomodulation in transplantation. This review focuses on current understanding of regulatory T cells and their role in transplantation tolerance.     

Treatment of hyperkalaemia using intravenous and nebulised salbutamol

In 11 children (aged 5-18 years) with end stage chronic renal failure, the effect on plasma potassium of two doses of salbutamol (separated by two hours) given intravenously (4 micrograms/kg) and on a separate date, of salbutamol administered by nebuliser (2.5 mg if the child weighed below 25 kg, 5 mg if above) was observed. Within 30 minutes of the first dose, the mean plasma potassium concentration fell significantly by 0.87 and 0.61 mmol/l after intravenous and nebulised administration respectively. Sixty minutes after the second dose the plasma potassium was significantly reduced by a further 0.28 and 0.53 mmol/l respectively. There was a significant difference between the two methods of administration at 300 minutes after the first dose favouring nebulisation. No major side effects were observed. Nebulised salbutamol should be the first choice emergency treatment of hyperkalaemia.     

Circumcision : A Time to Rethink

Background

Circumcision is one of the most routinely done surgery world over but has no scientific basis to enforce it on all patients. Of late, the operation has been criticized, non-operative methods have been tried and operations preserving the skin of prepuce have been recommended. The presence of physiological phimosis, which is self-correcting by the age of 15 years in children, needs to be differentiated from the pathological variety.

Method

The child population reporting to Surgery OPD was taken as sectional representative of the Indian communities and socioeconomic strata. A simple protocol was adapted to differentiate true phimosis from the physiological one and data collected. An observational study was done and data collected for last six years.

Result

566 children were referred to the hospital and only 212 were subjected to circumcision. Of these, 169 were cases of true phimosis, 7 had paraphimosis and the rest included 9 ritual circumcisions.

Conclusion

The incidence in this study is much less as compared to the series from the west. Though rare, this simple surgery is often fraught with complications. A refined approach has been planned for referring cases and selection for surgery thereby reducing unnecessary referrals and circumcisions.Key Words: Circumcision, Phimosis     

NEED FOR PRECISE PROTOCOL IN MAGNETIC RESONANCE IMAGING OF THE POST OPERATIVE SPINE

Gadolinium enhanced Magnetic Resonance Imaging (MRI) for the evaluation of the post operative lumbo-sacral spine is a sensitive and specific imaging technique. A need for establishing a specific protocol for Failed Back Surgery Syndrome (FBSS) for use in the service hospitals is highlighted for convenience of patient management and preservation of active manpower. The MR scan of 50 patients performed over a span of six months, who complained of persistent low backache even after surgery, were retrospectively analysed. The specificity of this series using MRI in indicating the exact cause of FBSS was clocked at only 30%. The conditions diagnosed were rectifiable. The balance of the patients who could not be offered any specific diagnosis towards the cause, were being managed conservatively / placed in low medical category for a considerable period. It was noted with concern that there was non prevalence of sequence like the fast spin echo with gadolinium enhancement as a routine.KEY WORDS: Gadolinium, Magnetic Resonance Imaging, Post-operative spine     

Mixed allogeneic chimerism and tolerance to composite tissue allografts

The development of effective immunosuppressive drugs has made solid organ allotransplantation the preferred approach for treatment of end-organ failure. The benefits of these immunosuppressants outweigh their risks in preventing rejection of lifesaving solid-organ allografts. On the contrary, composite tissue allotransplants are non-lifesaving and whether the risks of immunosuppressants justify their benefits is a subject of debate. Hence, composite tissue allografts (CTA) have not enjoyed widespread clinical application for reconstruction of large tissue defects. Therefore, a method of preventing rejection that would eliminate the need for toxic immunosuppressants is of particular importance in CTA. Bone marrow transplantation (BMT) to establish mixed chimerism induces tolerance to a variety of allografts in animal models. This article reviews mixed chimerism-based tolerance protocols. Their limitations and their relevance to CTA are discussed, highlighting some unique characteristics (high antigenicity and the presence of active bone marrow) that make CTAs different from solid organ allografts.     

Hand transplantation. A future clinical option?

Transplantation of a vascularized limb or its components is defined as composite tissue allotransplantation, and is one of the newest areas in surgery. To date, 24 hands have been transplanted onto 18 recipients. The initial results have been promising, and hand transplantation may become an important procedure for functional restoration of upper limbs. However, the ethical aspects of using chronic immunosuppression for a condition which is not life threatening have been the subject of debate. In this article, we review the field of composite tissue allotransplantation.     

Japanese Encephalitis : Is Routine Immunization Required?

Japanese encephalitis is the leading cause of viral encephalitis in Asia. In endemic areas annual incidence ranges from 10-100 per 100000 population. Case fatality averages 30% and a high percentage of the survivors are left with permanent neuropshychiatric sequelae. There is no effective drug treatment for this disease. In recent decades, Japanese encephalitis virus has caused epidemics in previously unaffected countries like India, Myanmar, Nepal, Sri Lanka, Thailand and Viet Nam. No effective environmental control is known. Although socioeconomic improvement and changes in agricultural practices are likely to reduce viral transmission, large-scale vaccination of affected populations with an effective and affordable vaccine appears logical at least in the short term. The impact of large-scale Japanese Encephalitis vaccination is documented in some regions of China and systematic vaccination has contributed to significant decline in incidence in Japan, Republic of Korea and Thailand.Key Words: Japanese encephalitis, vaccination