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Biomedical subjects

D J Allison

Publications and source records attributed to D J Allison.

At least 73 records · Page 4Linked to original sources
PubMed1986

Influence of alveolar hypoxia on pulmonary vasomotor responses to almitrine in the dog.

Almitrine bismesylate (5-10 micrograms/kg) was given as an intravenous bolus to anaesthetized, paralysed dogs with closed-chest (n = 5) and with open-chest (n = 7) in whom the retrocardiac lobe was separately ventilated. Pulmonary, lobar and systemic haemodynamics were measured under hypoxic, normoxic and hyperoxic conditions. Total pulmonary blood flow was measured by thermodilution and lobar flow by electromagnetic flow meter. In the closed-chest preparations, almitrine caused an increase in pulmonary vascular resistance (PVR) at all levels of inspired oxygen, the increments being 82% (30% O2), 91% (air) and 9% (13% O2). The control PVR varied inversely with arterial PO2 but there was no significant interaction between the almitrine and hypoxia induced vasoconstriction with multiple linear regression analysis. In the open-chest preparations, PVR and lobar vascular resistance (LVR) increased after almitrine by 48% and 41% respectively when both lung and lobe inspired 30% O2. When the lobe was switched to 12.5% O2 or nitrogen (lung inspiring 30%) PVR again increased (+52%) after almitrine but LVR decreased in five of seven lobes (lobar flow increasing despite constant cardiac output), the overall change being -4%. Analysis of covariance showed that the lobar response to almitrine was significantly different under hypoxic conditions compared with hyperoxic (P less than 0.05). With ventilation maintained constant, there was no significant change in arterial PO2 after almitrine in any experimental condition. In conclusion, almitrine is generally a pulmonary vasoconstrictor but can dilate vessels when they are constricted by local hypoxia. Almitrine does not enhance local hypoxic vasoconstriction in the dog.

Almitrine↗
PubMed1986

Bile duct obstruction: radiologic evaluation of level, cause, and tumor resectability.

In a prospective study of 65 patients with bile duct obstruction, various radiologic modalities were compared for their capability to demonstrate the level and cause of obstruction and to indicate accurately tumor resectability. Ultrasound (US) was performed in 65 patients, computed tomography (CT) in 51, direct cholangiography (DC) in 57, and angiography in 35. The level of obstruction was correctly indicated by US in 95% of patients and by CT in 90%, and the cause was correctly indicated by US in 88%, by CT in 63%, and by DC in 89%. In predicting tumor resectability, US was correct in 71% of patients, compared with 42% for CT, 58% for DC, and 25% for angiography. US therefore appears to be the single most useful modality in the evaluation bile duct obstruction.

Bile Duct Neoplasms↗
PubMed1985

Therapeutic embolisation of the hepatic artery: a review of 75 procedures.

In 75 procedures carried out in 57 patients, hepatic arterial embolisation was shown to be a safe and effective treatment for hepatic arterial bleeding and benign vascular tumours and malformations. The median survival of patients with malignant hepatic tumours in our series compares favourably with that recorded for other methods of treatment in patients with similar tumours. Embolisation ameliorated the symptoms produced by malignant hepatic tumours, particularly those occurring in patients with functioning endocrine tumours. The commonest side-effects of embolisation were pain, pyrexia, leucocytosis, intrahepatic gas formation, and nausea. Serious complications were rare and included hepatic abscess (4 patients), septicaemia (2 patients), renal failure (2 patients), and bowel infarction (1 patient). The 2 patients with septicaemia died within a week of embolisation, and these were the only deaths directly attributable to the procedure.

Arteriovenous Malformations↗
PubMed1985

Serum C-reactive protein response to therapeutic embolisation: possible role in management.

In a prospective study over 12 months, serum C-reactive protein concentration was measured serially in 20 consecutive patients who underwent therapeutic embolisation for various forms of malignancy and in 13 patients who had diagnostic coeliac or hepatic angiography without embolisation. All the patients who underwent successful embolisation showed a C-reactive protein response and in all cases the height of the response correlated well with the estimated size of the embolised tumour. Patients who recovered uneventfully showed a prompt fall in C-reactive protein from its peak values towards normal. In contrast, patients undergoing angiography alone showed only a minor increase in C-reactive protein concentration unless there were intercurrent complications. These results, together with the commercial availability of rapid and precise assays for C-reactive protein, indicate that serial measurement may be useful in the confirmation of tissue necrosis and assessment of its extent; also in the recognition of intercurrent complications following therapeutic embolisation.

C-Reactive Protein↗
PubMed1985

"Downhill" esophageal varices and occlusion of superior and inferior vena cavas due to a systemic venulitis.

A patient with a 10-year history of episodes of venous thrombosis, a high ESR, an elevated plasma polyclonal 1gG concentration, and bleeding from esophageal varices had obstruction of both superior and inferior vena cavas with "downhill" esophageal varices and a normal portal vein with normal portal pressure. Extensive investigations revealed no predisposing factor for the venous thromboses, but the patient made a good clinical response to steroids and dapsone, with no further episodes of bleeding nor evidence of major venous thrombosis. The causes and outcome of "downhill" varices are discussed.

Adult↗
PubMed1985

Iohexol and diatrizoate: comparison in visceral arteriography.

Iohexol, a low osmolality, nonionic contrast medium, and diatrizoate, a conventional, ionic contrast medium, were evaluated for patient tolerance during visceral arteriography. Almost all the procedures performed with iohexol were painless: most patients given this agent reported only a mild feeling of warmth. Diatrizoate produced some pain and a feeling of intense heat in most patients. Both media produced excellent radiographic results, and no serious adverse reactions occurred.

Abdomen↗
PubMed1985

The pre-operative embolisation of vascular malformations.

Large arteriovenous malformations frequently require surgical excision in order to prevent or treat the potentially serious problems they can cause ranging from haemorrhage and pain to cardiac failure. The surgery itself is usually difficult and often dangerous due to the serious risk of major intraoperative haemorrhage. Transcatheter arterial embolisation has greatly facilitated the management of small arteriovenous malformations but may only afford temporary relief of symptoms in very large lesions. Recanalisation of occluded vessels and revascularisation via previously insignificant collateral vessels means that large lesions cannot be effectively managed by this method alone. Previous surgery and ligation of feeding vessels may make effective embolisation difficult or impossible and a combined radiological and surgical approach to these lesions may permit definitive treatment. We present three cases in whom the pre-operative embolisation of buttock arteriovenous malformations facilitated successful surgical excision.

Arteriovenous Fistula↗
PubMed1985

A comparison of colonoscopy and selective visceral angiography in the diagnosis of colonic angiodysplasia.

The results of selective visceral angiography and colonoscopy were compared in the diagnosis of angiodysplasia of the large bowel. Fifty six patients were diagnosed as having angiodysplasia on angiography and 34 of these patients also underwent colonoscopy. Twenty three of the colonoscopies were positive giving a diagnostic yield of 68%. Three colonoscopies were negative and eight were incomplete. Colonoscopy was useful in the diagnosis of concomitant disease and also provided the clinician with the therapeutic possibility of electrocoagulation. Colonoscopy at operation proved to be a valuable technique in assessing the extent of angiodysplasia prior to resection.

Adolescent↗
PubMed1984

Obscure gastrointestinal haemorrhage of small-bowel origin.

The records of 37 patients investigated for obscure gastrointestinal haemorrhage originating from the small bowel were reviewed retrospectively. Bleeding was caused by Meckel's diverticula in eight cases, smooth muscle tumours in seven cases, vascular anomalies in 14 cases, and other single lesions in eight cases. The lesions were identified by angiography in 18 patients, operation in 17, and barium follow through examination in two. Only one patient under 50 years of age had a lesion that would not have been found by careful laparotomy. Early laparotomy is advisable in patients aged under 50 with obscure gastrointestinal bleeding; expert selective angiography is recommended before operation in patients aged over 50 and those who have already undergone a laparotomy yielding negative results.

Adolescent↗
PubMed1984

Pre-operative percutaneous transhepatic biliary drainage: the results of a controlled trial.

The operative mortality for biliary tract obstruction due to malignancy is high. In 1981 a controlled clinical trial of pre-operative percutaneous drainage was started at the Royal Postgraduate Medical School. At the time of percutaneous transhepatic cholangiography patients were randomized either to laparotomy or to pre-operative percutaneous transhepatic biliary drainage ( PTBD ) followed by laparotomy. Only patients with malignant biliary tract obstruction and serum bilirubin greater than 100 mumol/l were included. Seventy patients entered the trial, and five were withdrawn. Of the 65 remaining, 31 underwent laparotomy and 34 had pre-operative PTBD followed by laparotomy. The median duration of drainage was 18 days and during this time the median bilirubin fell from 305 to 115 mumol/l. Five patients required early surgery for complications of PTBD and two died within 30 days of surgery. The mortality for laparotomy was 19 per cent (6/31) compared with 32 per cent (11/34) for drainage plus laparotomy. This trial highlights the hazards of PTBD in high risk patients and has failed to demonstrate a reduction in mortality with the use of pre-operative PTBD .

Aged↗
PubMed1984

Right upper quadrant abdominal masses mimicking hepatic tumours: an approach to management.

Four patients with large right upper quadrant tumour masses of non-hepatic origin are presented. On initial clinical and radiological assessment, all cases were misinterpreted as either having a primary liver tumour or extensive invasion of the liver by an extrinsic tumour. Although angiography and CT scanning are most likely to yield an accurate diagnosis, they can be misleading. Vena cavography also gives important information in determining operability and at operation guides the retroperitoneal dissection. After thorough investigation an aggressive surgical approach to these tumours, with hepatic resection when necessary, provides the best chance of good palliation and possible cure.

Carcinoma↗