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Biomedical subjects

A C Steger

Publications and source records attributed to A C Steger.

16 recordsLinked to original sources
PubMed1992

Multiple-fibre low-power interstitial laser hyperthermia: studies in the normal liver.

Multiple four-fibre low-power interstitial laser hyperthermia was performed in the canine liver to establish the parameters with which large areas of thermal necrosis could be made. Using 1.5 W for 670 s (4020 J in total) and a fibre spacing of 1.5 cm, lesions with dimensions of 3.6 x 3.1 x 2.8 cm were achieved in 75 per cent of those attempted. There was no mortality and a low morbidity rate. These lesions could be visualized in both their development and resolution using ultrasonography. Healing occurred by 1 year. Temperatures in the centre of the heated region were 60 degrees C, which is more than enough to cause thermal cell death. There was good correlation between the temperatures recorded, the sonographic changes seen, and the pathological evidence of necrosis. Multiple-fibre low-power interstitial laser hyperthermia performed with ultrasonic guidance may be of use in the treatment of liver tumours.

Animals↗
PubMed1992

Ultrasound features of low power interstitial laser hyperthermia.

Low power interstitial laser hyperthermia (ILH) is a reliable means of producing in situ thermal necrosis. Ultrasonic studies have been carried out of the changes that occur in canine liver during ILH performed at laparotomy. With a single fibre delivering Nd-YAG laser at 1-1.5 W for 670 s an hyperechoic region developed at the fibre tip measuring 5-6 mm in diameter; around this developed an area of hypoechoic change (up to 500s) giving a total area of changed echogenicity of 14-16 mm. With a multiple fibre system using 4 laser fibres simultaneously the sonographic changes were a summation of the changes seen with a single fibre, the hypoechoic areas overlapping. With this four fibre system the creation of large (3.5 x 2.8 cm) areas of thermal necrosis was possible. There was good correlation between the sonographic and pathological measurements of the region of thermal change. The sonographic studies showed the extension and overlap of regions of thermal necrosis and allowed visualization and accurate measurement of the area undergoing change. The same combined technique has been successfully applied in a small number of clinical cases and may be of use in the treatment of tumours in solid organs.

Animals↗
PubMed1992

Interstitial laser hyperthermia: a new approach for treating liver metastases.

The palliative management of hepatic metastases remains unsatisfactory. There is a need for a simple non invasive technique which can stop or retard the rate of tumour growth. In principle, Interstitial Laser hyperthermia may fulfil such a role. In experimental studies, this technique produced precise in situ necrosis within solid organs which healed safely. In a pilot feasibility study, we treated ten patients with a total of 18 hepatic metastases on 31 occasions using a percutaneous approach to achieve an overall objective response rate of 44%. The treatment proved simple to perform, was well tolerated and produced radiological evidence of necrosis in small metastases (diameter less than or equal to 3 cm). However, further research is required before the technique can be regarded as established. Its future role in most cases will be to control the growth of discrete hepatic metastases unsuitable for resection. In instances where the extent of necrosis can be matched accurately to tumour volume, the potential for cure exists.

Aged↗
PubMed1991

Role of interstitial therapy in the treatment of liver cancer.

Conventional palliative management of inoperable focal hepatic tumours remains unsatisfactory. Interstitial techniques such as cryotherapy, alcohol injection, low power laser hyperthermia and interstitial radiotherapy offer alternative approaches. Cryotherapy is an effective and precise technique for inducing tumour necrosis. It can only be performed at laparotomy making it relatively invasive and retreatment impractical. Alcohol is cheap and can be injected percutaneously. However, inhomogeneous distribution produces imprecise and nonreproducible lesions. Low power laser hyperthermia produces precise and reproducible areas of necrosis that are roughly spherical in shape. At present, this technique is most effective for small tumours. Interstitial radiotherapy remains the least evaluated of all the interstitial techniques. Unlike cryotherapy and low power laser hyperthermia, the biological effect of ethanol injection and interstitial radiotherapy cannot be monitored in real time by ultrasound. With the exception of cryotherapy, all methods can be applied percutaneously with low morbidity and mortality. None of these techniques is established, but they may offer the prospect of cure in cases where all areas of tumour can be positively identified and fully treated. However, in most instances the intention is to control the growth of relatively small discrete volumes of tumour within the hepatic parenchyma.

Alcohols↗
PubMed1990

The influence of immunosuppression on peptic ulceration following renal transplantation and the role of endoscopy.

Peptic ulceration is common in patients undergoing renal transplantation. With a change in routine immunosuppression from azathioprine and steroids to cyclosporin, or cyclosporin and low-dose steroids and azathioprine, less peptic ulceration might be expected. This was investigated in two groups of patients undergoing renal transplantation. Group 1 (n = 90) received azathioprine and prednisolone; Group 2 (n = 44) received cyclosporin and low-dose azathioprine and prednisolone. Patients from both groups were endoscoped 7-14 days after operation, when peptic ulceration, oesophagitis, gastritis, and duodenitis were assessed. Whilst Group 2 differed significantly in receiving more methylprednisolone than Group 1 (P less than 0.05), there was no difference between the two groups with regard to the incidence of peptic ulceration or inflammatory lesions. In both groups there was a trend for those treated with methylprednisolone for rejection to develop ulcers or inflammatory lesions when a total dose of more than 2 g had been given by the time of endoscopy. Any possible reduction in the incidence of peptic ulceration after transplantation is outweighed by the continued use of high-dose methylprednisolone to treat episodes of rejection. The true incidence of peptic ulceration after transplantation is much higher than if presenting symptoms alone are the starting point for investigation. Regular post-transplantation endoscopy allows prompt diagnosis and treatment, with attainment of a very low mortality rate (0.75% overall, or 4% in those with peptic ulcers) from peptic ulceration in patients undergoing renal transplantation.

Adolescent↗
PubMed1989

Interstitial laser hyperthermia: a new approach to local destruction of tumours.

The use of local hyperthermia to treat cancer of the internal organs has been limited by the difficulty of controlling delivery of heat and limiting the effects to the tumour, but this can be overcome by using laser light transmitted through thin flexible fibres. Laser energy was delivered to tumours through fibres inserted percutaneously through needles directly into the centre of the tumour area. Ultrasound scanning was used to locate the tumour, position the fibres correctly within the tumour, and monitor the development of thermal necrosis in real time during laser exposure and through the subsequent period of healing. Five patients were treated (one with a tumour of the breast, one with a subcutaneous secondary tumour, one with a recurrent pancreatic tumour, and two with secondary tumours in the liver). Tumour necrosis was found on ultrasonography or computed tomography in all, and there were no immediate or delayed complications. In one patient the size of the isolated secondary tumour in the liver had not increased over 10 months, and he subsequently showed no other evidence of residual cancer. To develop this technique careful studies are essential to ensure that in every case the extent of thermal necrosis produced by absorption of the laser light can be matched to the full extent of the tumour being treated and that there is always sufficient adjacent normal tissue to ensure safe healing. These preliminary results suggest that this simple technique can be applied safely and effectively to common tumours in humans; more extensive trials in a range of cancers of solid organs are warranted.

Breast Neoplasms↗
PubMed1988

Contact laser or conventional cholecystectomy: a controlled trial.

There have been claims that the use of lasers in surgery is associated with reduced operative blood loss, trauma, postoperative pain and improved postoperative mobility. With the development of sapphire probes capable of transmitting neodymium yttrium aluminium garnet (Nd: YAG) laser light, it is now feasible to perform direct-contact low-power laser surgery. In a small randomized controlled trial, we have compared cholecystectomy performed by conventional methods (n = 11) with the same operation performed by contact laser (n = 10). Operative time, blood loss, operative stability, analgesic requirement, mobility and response to the trauma of surgery were compared. The only differences between the two groups were a significantly increased wound infection rate (P = 0.051) in the laser surgery group and a significantly increased length of operating time (P = 0.001). Thus, the laser did not confer any advantage over conventional surgery.

Cholecystectomy↗
PubMed1987

Gastrointestinal haemorrhage from a second source in patients with colonic angiodysplasia.

Angiodysplasia of the colon is increasingly recognized as a cause of obscure gastrointestinal haemorrhage. On review of 71 patients with angiodysplasia, 40 came to surgery. Of these, nine (22.5 per cent) were also found to have small bowel lesions, either at the original laparotomy (7) or later when further investigations were performed for recurrent bleeding. Angiodysplasia can only be confidently diagnosed as the source of blood loss if seen to be actively bleeding. If a synchronous small bowel lesion is seen, we recommend that it should be removed at the same time as the colectomy.

Blood Vessels↗
PubMed1987

The palliative endoscopic treatment of inoperable oesophagogastric and rectal cancers: a low power direct contact laser technique.

The palliative treatment of inoperable cancers of the oesophagus, gastric fundus and rectum can be difficult and unsuccessful. Laser beam irradiation therapy offers good palliation in the majority of patients but requires several treatment sessions to achieve this. We describe a small series of patients treated with a new direct contact low power laser technique using artificial sapphire probes. After one treatment, in patients with malignant dysphagia, two thirds could swallow solids and in patients with rectal cancers bleeding was stopped or reduced and diarrhoea stopped. The interval before a second treatment was needed was three and a half weeks. We feel this technique is a useful adjuvant to conventional laser therapy of inoperable gastrointestinal tract tumours, especially in providing effective palliation in one treatment session.

Adenocarcinoma↗
PubMed1987

Remaining indications for vagotomy with drainage or antrectomy in duodenal ulcer.

Proximal gastric vagotomy (PGV) consists of denervation of the body and fundus of the stomach, the antral nerve supply being left intact. It has a low operative morbidity and mortality and there are few postvagotomy side effects. However, the recurrent ulcer rate may be higher than with other operations for duodenal ulcer. Nevertheless it is usually easier to treat post-PGV recurrence than the complications of other gastric acid lowering operations. This study defines those patients in whom we have not performed a PGV. Of 110 operations for duodenal ulcer since 1980, 70 were PGVs while 40 consisted of truncal or selective vagotomy combined either with a drainage procedure or antrectomy. It is our practice not to perform a PGV in those patients with prepyloric ulcers, pyloric stenosis, bleeding or perforated ulcers and recurrent ulcers.

Adult↗