Sitting can cause ischaemia in the subcutaneous tissue of the buttocks, which implicates multilayer tissue damage in the development of pressure ulcers.

A better understanding of how pressure ulcers develop in the buttocks will improve prophylactic measures. Our aim was to investigate signs of reduced perfusion and ischaemia in the subcutaneous fat in the buttocks during sitting. A microelectrode was used to quantify oxygen (pO(2)). Metabolites that indicate aerobic or anaerobic metabolism (glucose, lactate, pyruvate, and glycerol) were quantified using microdialysis. Sixteen healthy people were studied while they sat on a wheel chair cushion, and a hard surface. Sitting pressures were mapped, and the thickness of the subcutaneous fatty layer was measured. The results showed that pO(2) and glucose were significantly reduced during sitting, and for pO(2) the effect is significantly more profound during sitting on a hard surface. After loading, both glucose and pO(2) increased significantly. We conclude that the subcutaneous adipose tissue covering the ischial tuberosities becomes ischaemic during sitting. This finding supports the theory that not only is the skin involved in early development of pressure ulcers, but also the deeper tissues.

Survival and function in patients with tumours of the head and neck operated on and reconstructed with free flaps.

From 1983 to 2003, 131 patients were operated on in the head and neck region with 139 free flaps. They were operated on using a team approach of ear, nose, and throat surgeons and plastic surgeons, and sometimes maxillofacial surgeons. The tumours were squamous cell carcinoma (SCC) 104 (80%), salivary gland cancer 13 (10%), sarcoma 5 (4%), basal cell carcinoma 4 (3%), and others 4 (3%). The staging of the primary intraoral SCC tumours (n=79) was 42% in stage II, 28% in stage III, and 30% in stage IV. The survival of patients with primary oral SCC was compared with a previously treated previous series that gave an increase in tumour-related five-year survival from 48% to 58%. Most flaps were radial forearm flaps (73%). Fifteen percent were vascularised bone transfers. A questionnaire was sent to patients who had had oral/oropharyngeal tumours to measure function and satisfaction, to which 47/49 responded. The results including ability to chew and swallow; speech was good, with a median score of 0.78 (range 1-0).

Perfusion of buttock skin in healthy volunteers after long and short repetitive loading evaluated by laser Doppler perfusion imager.

Frequent unloading is vital to avoid pressure ulcers of the seat area in patients with injuries to the spinal cord. The duration of unloading is probably as important as that of the sitting period in the prophylaxis of pressure ulcers. The aim of this study was to investigate the microcirculatory reactions after occlusion of the buttock skin after repeated ischaemic provocation. The perfusion of buttock skin was studied with a laser Doppler perfusion imager (LDPI) in healthy people after short and long periods of sitting (repeated four times). The perfusion increased significantly during the consecutive loadings compared with the first loading, and this effect was more profound after the long load. Repeated periods of ischaemia of the buttock skin without allowing the tissues to recover resulted in increasing reactive hyperaemia, and are therefore probably more damaging than single loadings. This is important when establishing clinical guidelines for the prophylaxis of pressure ulcers in patients with spinal cord injuries.

Perfusion of the skin of the buttocks in paraplegic and tetraplegic patients, and in healthy subjects after a short and long load.

In patients with spinal cord injuries (n=8) and healthy controls (n=8) the hyperaemic response in the buttock skin after sitting on a hard surface was studied using a laser Doppler perfusion imager. They sat for three minutes (short load), or 15 minutes (long load). An exponential mathematical function was used to compare the mean perfusion during the observed interval. The results showed that preloading perfusion is significantly higher among patients than healthy subjects. In both groups, the microcirculation of the skin increased significantly after loading, and peak perfusion was significantly lower after the short load. The mean perfusion was higher among the patients after both loadings, which suggests that there was stronger ischaemic provocation. The main outcome was that there was a dose-response relation between duration of loading and intensity of reactive hyperaemia, and that patients with spinal cord injuries have greater perfusion before and after loading than healthy controls.

Laser Doppler perfusion imaging of the radial forearm flap: a clinical study.

Laser Doppler perfusion imaging (LDPI) allows non-invasive assessment of blood flow in a predefined area of skin rather than at one single point. We have used LDPI to study the pattern of skin blood flow in the radial forearm flap before and after the flap has been raised. The data were collected from a consecutive series of 11 patients with cancer of the oral cavity or oropharynx in whom the radial forearm flap had been used during the reconstructive procedure. Reperfusion leads to an immediate hyperaemic response both in the flap and the surrounding skin. This hyperaemia remains for at least the first 30 minutes after reperfusion. The perfusion of the radial side of the forearm skin distal to the flap is significantly lower than that on the ulnar side after the skin island has been raised and the distal artery divided. We suggest that LDPI is useful for monitoring the perfusion of free skin flaps.

Are mechanical microvascular anastomoses easier to learn than suture anastomoses?

Sutured anastomoses of small vessels are considered difficult to learn. Mechanical anastomosis systems allow a more rapidly performed anastomosis. In order to compare the process of learning to perform sutured and mechanical microvascular anastomoses, two surgeons, with limited microvascular experience, performed 30 aortic and 30 femoral vein anastomoses in 30 Wistar rats. The methods compared were conventional suture, vascular closure system (VCS) and microvascular anastomatic coupler system (MAC). There were no inter-surgeon differences regarding patency or time to perform anastomoses. The average time to perform a suture anastomosis was 39 min (patency 80%). Anastomoses with the VCS system took 24 min (patency 25%), whereas the MAC couplers took 13 min to perform (patency 95%). There was a significant learning effect with sutures, but no obvious reduction in time to perform MAC coupler or VCS clip anastomoses was seen. MAC couplers were easiest to use, and allowed us to perform rapid anastomoses with high patency.

Morphological and functional evaluation of leg-muscle reinnervation after coupler coaptation of the divided rat sciatic nerve.

Mechanical couplers are successfully used for microvascular venous anastomoses. The advantages include a simple and fast technique and a high patency rate. Couplers offer a secluded coaptation site, and might also be of use in peripheral nerve repair. The present study was designed to investigate coupler coaptation of the rat sciatic nerve, evaluating the number and locations of motor and sensory neurons projecting to the selected muscles as well as stimulation-induced muscle contraction force. Adult rats underwent either suture or coupler repair after left sciatic nerve transection. In all rats, the experimental side was compared to the healthy right side. Evaluation after 20 weeks included retrograde labeling of motoneurons and dorsal root ganglion neurons projecting to the tibial anterior muscle and to the tibial posterior muscle, histology, muscle contraction force (tibial anterior muscle and gastrocnemius muscle), and a pinch reflex test. The results show that the suture and the coupler groups did not differ significantly regarding the examined parameters, except for discrete signs of nerve compression at the coaptation site after coupler repair due to fibrous tissue ingrowth. However, this did not impair axonal regeneration. Importantly, axonal outgrowth from the repair site to the surrounding tissue was not observed after coupler coaptation, but it was observed after suture repair. These results suggest that couplers may be of value for repair of nerves in adjacency to avoid axonal crisscrossing between nerves during regeneration.

Our experience using the vertical rectus abdominis muscle flap for reconstruction in 12 patients with dehiscence of a median sternotomy wound and mediastinitis.

The vertical rectus abdominis (VRAM) flap has been used for reconstruction of sternal defects, particularly in the inferior third, since it was first described 20 years ago. We describe 12 patients with mediastinitis or chronic sternal osteomyelitis after sternotomy treated between 1994 and 1997, nine performed at the Royal Hospitals Trust, London. Sternal osteomyelitis and mediastinitis after median sternotomy is an uncommon (0.4%-8.4%) but often fatal condition. Vascularised pedicles are the treatment of choice, and VRAM flaps were used in all cases. We report good long-term outcome with a follow up of 2-5 years, and no long-term morbidity relating to the VRAM reconstruction. We had only one partial failure of a flap. The operations were largely done in hospitals away from the plastic surgical unit in extremely sick patients, which illustrates the importance of multidisciplinary management to reduce hospital stay, mortality, and morbidity. We argue that early involvement of plastic surgical specialists in the treatment of sternal dehiscence is essential to ensure a successful outcome.

Sitting pressure and perfusion of buttock skin in paraplegic and tetraplegic patients, and in healthy subjects: a comparative study.

The distribution of sitting pressure and ability to respond with reactive hyperaemia were studied in a group of paraplegic and tetraplegic patients (n = 8) with spinal cord lesions and healthy controls (n = 10) using a pressure sensitive plate and laser Doppler perfusion imager. The results show that the mean sitting pressure of the patients was 9.9 N/cm2 (left) and 11.7 N/cm2 (right) compared with 3.5 N/cm2 (left) and 3.6 N/cm2 (right) in controls. The differences were significant on both the left (p < 0.01) and right (p < 0.05) sides. The maximum pressure in patients was 42.9 N/cm2 (left) and 48.7 N/cm2 (right), and in controls 12.0 N/cm2 (left) and 12.9 (right) (p < 0.01). Both groups showed a reduction in skin perfusion in the seat area during sitting compared with unloaded resting, and in the controls it was significantly increased (p < 0.001 on both sides) during the reactive hyperaemic phase immediately after sitting. Compared with the preload values, the patients showed a similar but slightly weaker picture significant on the right side (p < 0.05), but not on the left. The hyperaemia was not uniformly distributed, but occurred where the pressure was greater than 2 N/cm2. There was no correlation between the amount of reactive hyperaemia and absolute values of sitting pressures. We conclude that tetraplegic and paraplegic patients have significantly higher sitting pressures than normal controls, and that the hyperaemic response in the buttock region in the upright position after pressure load is slightly weaker in the patients, which could be of importance for the development of decubitus ulcers.