Plasma arginine vasopressin levels and arterial pressure during open heart surgery.

A study of plasma arginine vasopressin (AVP) levels and their relation to changes in arterial pressure was undertaken in 13 patients undergoing open heart surgery. Seven of the patients received high doses of intravenous morphine (1 or 2 mg/kg) as part of their anaesthetic, whereas the other six did not. Increases in the AVP levels during cardiopulmonary bypass (CPB) were significant in both groups, but were significantly greater in the patients not receiving morphine (median 86.1 fmol/ml) than in those who did (47.5 fmol/ml). In both groups there was a linear correlation between the natural logarithm of the plasma AVP level and the percentage fall in the mean arterial pressure, although the slope of the relationship was significantly less in the group receiving morphine than in the group not receiving morphine. These results indicate that in patients undergoing cardiac surgery the neuroendocrine reflex control of plasma AVP levels in relation to changes in arterial pressure is intact, but that the sensitivity of the reflex (i.e. the increase in plasma AVP level for a given fall in arterial pressure) is reduced by the administration of high doses of intravenous morphine.

The role of autonomic neuropathy in diabetic foot ulceration.

Five standard, non-invasive tests of cardiovascular, autonomic function were performed in each of four groups of 30 subjects: controls, group 1, diabetics without clinical evidence of neuropathy; group 2, diabetics with neuropathy, but without foot ulceration; group 3, diabetics with neuropathic ulceration of the foot. The results showed a significant impairment of autonomic function in diabetics without clinically demonstrable somatic neuropathy compared with controls diabetics with somatic neuropathy compared with those without diabetics with neuropathic ulceration compared with those with neuropathy without ulceration. Parasympathetic function was more seriously affected than sympathetic. In patients who had only mild sensory neuropathy on clinical assessment, those with ulcers had significantly greater impairment of autonomic neuropathy compared with those with uncomplicated neuropathy.

The effect of vasopressin on solute and water excretion during and after surgical operations.

The relationship between the concentration of plasma arginine vasopressin (AVP), urine volume, and osmolality during and after an abdominal operation was studied in nine patients. In all patients the AVP level rose well above that necessary for maximal antidiuresis (5 fmol ml-1) and then returned to within the normal range (0.5-5.0 fmol ml-1) usually over the next 24 hours. During this period of raised AVP concentration the urine volume, which varied considerably, was closely related to osmolar excretion. With the fall of AVP to normal levels, all but one of the patients eventually exhibited positive free water clearance. However, in most patients the urine remained hypertonic for some hours and its volume continued to be determined mainly by osmolar load which was itself apparently related to glomerular filtration rate. At no time was there a significant relationship between changes in plasma AVP concentration and urinary volume.

Cellulose granulomatous peritonitis.

The case history of a patient developing granulomatous peritonitis due to cellulose is described. At a second laparotomy following an operation for intestinal obstruction due to adhesions, the peritoneum was found to be studded with multiple, yellow nodules, closely resembling tuberculous lesions, but shown on microscopy to be tuberculoid granulomata containing cellulose fibres. The main features of the condition, which is self-limiting, and probably more common than is generally realized, are discussed.

The use of graduated compression stockings in the prevention of postoperative deep vein thrombosis.

The efficacy of graduated compression stockings in the prevention of postoperative deep vein thrombosis was studied in a randomized, prospective, controlled trial of 200 patients, aged 40 years and over, undergoing abdominal surgery (100 for benign disease, 100 for malignant conditions). Deep vein thrombosis was diagnosed by the 125I-fibrinogen test. The incidence of deep vein thrombosis was 35.9 per cent in the control group (103 patients) and 15.5 per cent in the stockinged group (97 patients) (P less than 0.025). In the patients with benign disease, deep vein thrombosis developed in 24.5 per cent of the control limbs and 6.1 per cent of stockinged limbs (P less than 0.005); in patients with malignant disease the similar figures were 27.9 and 11.5 per cent (P less than 0.05). Increasing age did not alter the efficacy of the stockings. It is concluded that graduated compression stockings provide a safe and effective method of prophylaxis against deep vein thrombosis.

Method of healing diabetic forefoot ulcers.

Six diabetic patients with neuropathic ulceration of the sole of the foot (seven feet, eight ulcers) were treated by the application of a below knee walking plaster with a rubber rocker. All the ulcers healed with this treatment, greatly reducing the usual period of hospital inpatient stay. After healing, study of the forces acting on the sole of the foot showed that these ulcers occur at the site of maximal horizontal shear force and confirmed that they occur at the site of maximal vertical force. This treatment is highly effective for neuropathic ulcers of the sole not affecting bone or complicated by deep sepsis. There may be a high rate of recurrence, however, reflecting inadequacy of methods of protecting damaged neuropathic feet.

Forces under the foot.

A transducer has been developed to record the shear or horizontal components of force beneath the sole of the foot. When used with a vertical force transducer it has enabled a comprehensive analysis of the mechanical forces acting beneath the foot when walking in various types of footwear. Considerable differences have been recorded between the footwear. Particularly low forces are present in a plaster cast and to a lesser extent with Plastazote insoles. The possible application of these findings to the management of ulceration of the sole of the foot in diabetes mellitus and leprosy is discussed.

Vertical forces acting on the feet of diabetic patients with neuropathic ulceration.

The vertical forces acting on the sole of the foot in walking have been measured in 24 diabetic patients with neuropathic ulceration of the foot using a load-sensitive surface divided into 128 load cells, and compared with those in two groups of controls: (a), 21 diabetic patients with peripheral neuropathy but no ulceration and (b) 47 normal individuals. The results showed that the patients with neuropathic ulceration were significantly heavier, that diabetic patients with neuropathy, with or without ulceration, transmitted proportionally less force through the toes than normal individuals, and showed a medial shift of the force transmitted through the metatarsal heads. All plantar ulcers occurred at the site of maximum loading. The absolute force at the site of maximum loading was significantly greater in the patients with ulcers than in both control groups, through there was a considerable overlap. A significant difference remained even when the absolute force had been corrected for differences in toe loading and body weight, indicating that a further factor (or factors) must contribute to the development of these localized areas of high loading.

Arginine vasopressin release following surgical operations.

A study of plasma arginine vasopressin (AVP) concentrations in 16 patients undergoing uncomplicated cholecystectomy was carried out to determine the relative importance of the various stimuli to AVP secretion during and after an operation. Eight of the 16 patients were given a high epidural blockade from T4 and T12 and blood samples were taken before, at frequent intervals during and for two days after operation for determination of plasma AVP and osmolarity; systolic blood pressure was measured each time a blood sample was taken. In the 16 patients there was a 1.8-fold rise of plasma AVP after induction of anaesthesia (from 1.7 pmol/l median basal value to 13.1 pmol/l) and an 8.8-fold rise after skin incision, the highest concentration during operation being 102 pmol/l. There was no significant difference in AVP concentrations, urine volumes or plasma osmolality in the control and epidural groups. Systolic blood pressure fell in all patients during operation by between 14 and 54 per cent, the fall being significantly greater in the epidural group. Notwithstanding the evidence that certain nervous impulses do cause an increased secretion of AVP during operation, these results clearly show that in the absence of such stimuli there is still an increased secretion, almost certainly caused by a fall in the blood pressure.

Is preoperative localisation of insulinomas necessary?

During the past 20 years 33 patients suspected of harbouring an insulinoma have been investigated. 29 had laparotomy, and tumours were removed from 27.2 of the 29 and 1 other proved not to have an insulinoma, although preoperative imaging had suggested a tumour. Four different localisation procedures were used, and in some patients more than one technique was applied. Selective arteriography of branches of the coeliac axis showed the position of the insulinoma correctly in 9 out of 18 cases, but in all of these the tumour was felt at operation, so that the information provided was unnecessary. Arteriography gave false localisation in 4 patients and missed the tumour completely in 4 but was also negative in 1 patient not harbouring a tumour. Ultrasonic examination provided correct localisation in only 2 out of 11 instances and computer-assisted tomography in 1 out of 8. Insulin estimation in blood obtained at percutaneous transhepatic portal-venous sampling (THPVS) provided correct localisation in 2 out of 8 cases, but in only 1 of these was it needed to guide pancreatic resection. Localisation was spurious in 5 patients, and in 1 there was no evidence of a tumour at all. In 23 patients the surgeon felt and removed the insulinoma at the first operation. In 3 tumour was palpable at a second laparotomy some years later. In only 1 was no tumour felt at operation. The false-positive findings in the THPVS were caused by misinterpretation of data. For a peak of insulin concentration in the portal vein to be meaningful, it should exceed 200 mU/l and to be fully diagnostic it should be greater than 500 mU/l. Present imaging techniques are not precise enough to localise an insulinoma. An experienced surgeon has a very high probability of being able to palpate the tumour at operation, and preliminary localisation is therefore not needed in most cases.