Abstract
This project was an attempt to develop a simple technique which could detect the potential of healing of the skin if an amputation is performed in an ischaemic limb. This would help the surgeon to decide the level of amputation which would heal primarily, minimising the number of failures. In the first few Chapters, historical aspects, amputation, prosthesis, circulation and microcirculation are described. Haemodynamics, microcirculation and physiology of nutrition in the limb are discussed in detail. Various investigations to detect the nutrition/circulation of the limb and procedures to improve the circulation are analysed and discussed. The proposed method is based upon the principle that oxygen which under special circumstances diffuses out through the skin is highly correlated with the oxygen present in the cutaneous tissues. It is suggested by the author that this oxygen level indicates the healing capability of the tissues since the healing is related to the availability of the oxygen. The instrument used for this project is the TCM 1 TC oxygen monitor and the Clark type electrode developed by Radiometer, Copenhagen, Denmark. This instrument is, at present, being used for monitoring arterial oxygen levels in infants and premature babies suffering from respiratory defficiency. The oxygen which is diffused out, is highly correlated to the arterial oxygen level and is displayed in numerical form in the monitor (mm Hg). TC pO[2] (oxygen tension measured transcutaneously) measurements were carried out on ischaemic limbs. The results of the treatments were correlated with the previously recorded TC pO[2] values, which were not taken into account in deciding the line of treatment by the surgical team. The TC pO[2] values were also recorded on the volunteers and a comparative study of TC pO[2] values on ischaemic and non ischaemic limbs (volunteers) was made. It was noticed that TC pO[2] values reduced as age advanced and these values further reduced as the ischaemia increased. It has been inferred that TC pO[2] values give a good idea of healing potential of the wound if an amputation is performed. The ratio of TC pO[2] value at the ischaemic site with the control site (infra clavicular region on the chest wall) which has been termed as "Healing Index" by the author is a better representation of the healing potential of the amputation wound and can be a good guide for deciding the level of amputation which would heal primarily. The investigation can also be used for comparing the results of treatment on ischaemic limbs. The effect of praxilene was examined and it was found to be helpful in cases where the decision for amputation was controversial. It improved the nutrition of the ischaemic limb specially when it was at a critical level. It was also observed that oxygen inhalation at the rate of 4 litres per minute by a face mask improved the availability of oxygen to the peripheral tissues. It appears that this simple procedure may change the result of amputation. This requires further investigations. In the end a few improvements in the instrument have been suggested and other applicabilities of TC pO2 values have been described. The experimental procedure has been simplified and has been handed over to the Limb Pitting Centre and the surgical team of Queen Mary's Hospital, Roehampton, London. The estimation of TC pO2 values are now being carried out routinely on ischaemic limbs as an adjunct to the clinical assessment to help the surgeon when deciding the level of amputation.