Assessment of tissue viability in relation to the selection of amputation level

Thermal imaging today and its relevance to diabetes

From the historic and simple assessment of temperature by the clinical thermometer, modern infrared technology has opened up new perspectives, especially in the use of thermal imaging to map body surface temperature with a remote sensing camera. Since the 1960s, there is now a greater understanding of thermal physiology and the relationship between skin temperature and blood perfusion. Furthermore, the examination technique, and the advantages of computer-aided digital imaging has greatly improved the reliability of this technology in medicine. Studies in diabetology have shown the value of this new facility and its relevance to clinical assessment of peripheral perfusion and tissue viability.

Developments in transcutaneous blood gas monitoring: a review

Transcutaneous measurements of oxygen (tcPO2) and carbon dioxide (tcPCO2) are useful in the intensive care unit because they provide continuous and non-invasive estimation of arterial blood gases. In patients with compromised peripheral blood flow the cutaneous values will reflect the haemodynamic changes as blood is shunted away. They have been increasingly used in a variety of clinical situations, such as assessment of skin flap viability, drug evaluation, prediction of wound healing and selection of amputation level in peripheral vascular disease. From a review of available literature it appears that transcutaneous monitors have found another application as indicator of local tissue perfusion.

Prosthetics, orthotics, and assistive devices. 1. General concepts

This self-directed learning module highlights the general concepts and new advances in the area of orthotics and prosthetics. This general overview is part of the chapter on prosthetics, orthotics, and assistive devices for the Self-Directed Medical Knowledge Program Study Guide for practitioners and trainees in physical medicine and rehabilitation. This section contains essential information on spinal, lower and upper limb orthotics, lower and upper limb prosthetics, juvenile prosthetics, kinesiology, motion analysis, and assistive devices such as canes and crutches. This article establishes a foundation on which the second, third, and fourth articles of this chapter will build. The three articles to follow review newer developments in specialized seating and assistive devices, prosthetics, and the orthotic management of selected disorders.

Further experience in the healing rate of lower limb amputations

Results of lower limb amputation in the Tayside Region in the years 1981-1985 have been analysed. Three-hundred and twenty-four amputations were performed on three-hundred and eight patients. Two-hundred and thirty-six amputations were attempted at the below-knee level. Only 19 required proximal revision. Prior to amputation, all patients should have a detailed vascular assessment, and the operation should be performed by experienced amputation surgeons using meticulous technique.

The influence of smoking on the level of lower limb amputation

A review of smoking habits of 77 vascular related amputees demonstrated a high incidence of smoking significantly greater for men than in the general population. Male smoking amputees with atherosclerosis related peripheral vascular disease were found to have a high risk of having an above-knee amputation. Those with diabetes mellitus whether male or female, smokers or not, had a significantly greater chance of having a below-knee amputation. Overall, non-smokers were found more likely to have a below-knee amputation than an above-knee (p less than 0.05).

Fate of the vascular patient after below-knee amputation

50 below-knee amputations were carried out in 45 patients (25 men and 20 women), mean (SD) age 73 (10.5) years. The mean survival time was 22(16) months after the operation. In each patient the healing potential of a below-knee amputation was determined preoperatively by segmental pressure studies and thermographic delineation of skin perfusion. 33 of the stumps healed by first intention, in 14 healing was delayed but occurred without the need for further surgery, and 3 stumps healed after local wedge excision. The initial mobilisation rate was 90%. Thus, there are no grounds for carrying out an initial above-knee amputation to save the patient a further operation.

Oxygen inhalation induced changes in the skin as measured by transcutaneous oxymetry

Transcutaneous oxygen (PtcO2) measurements were made on 46 patients with severe ischaemia of the lower limbs and on 17 age-matched controls. Values breathing air, 100 per cent oxygen and the rate of change of PtcO2 breathing oxygen were recorded. Of 29 below knee amputations there were 4 failures; 16 had PtcO2 values less than 35 mmHg, but 12 of the 16 healed. When the rate of change of PtcO2 during oxygen inhalation was greater than 9 mm Hg/min all below knee amputations healed; all 4 failures were found to have values less than 9 mm Hg/min while only one patient with a value of less than 9 mm Hg/min healed a below knee amputation. This study shows that low PtcO2 values are a poor indication of healing potential. A more reliable index of skin viability is provided by the dynamic measurement of PtcO2 changes during oxygen inhalation. The addition of an oxygen inhalation test, when making PtcO2 measurements, greatly enhances the applicability of the technique in the assessment of the oxygen supply to the skin.

A rationale for skew flaps in below-knee amputation surgery

The use of thermography in the assessment of amputation levels has demonstrated a medial to lateral thermal gradient in many cases. In order to see whether this reflected a true medial to lateral skin blood flow gradient, a prospective study was set up to measure blood flow medially and laterally below the knee. Twenty-one patients, presenting for amputation assessment with end-stage peripheral vascular disease, were studied. Skin blood flows were measured using an intradermal radioisotope clearance technique. Results showed a highly significant difference between medial and lateral skin blood flows (t = 4.79; p less than 0.001). In view of the significantly higher blood flow in the medial skin of the lower leg, it is suggested that a more medially based posterior below-knee amputation skin flap may be of more value in some patients.