PubMed HealthSearch

Biomedical subjects

A W Duncan

Publications and source records attributed to A W Duncan.

At least 19 recordsLinked to original sources

Intracranial large vessel vasculopathy and anaplastic meningioma 19 years after cranial irradiation for acute lymphoblastic leukaemia.

A child was diagnosed in 1969 as having acute lymphoblastic leukaemia (ALL) and received chemotherapy. On bone marrow relapse in 1973, he was treated with cranial irradiation (20 Gy) in addition to chemotherapy. He continues in complete remission 19 years after his relapse. At age 25 years, he presented with headaches and left hemiparesis. Computerised tomograph demonstrated a large, enhancing right-sided intracranial tumour. Angiography was performed and showed the right internal carotid artery was occluded. Most of the right hemisphere was supplied from the external carotid via the middle meningeal artery. The left posterior cerebral artery and the left anterior cerebral artery were absent presumably as a result of radiation-induced arteritis. A resection of an anaplastic meningioma arising from the right sphenoidal ridge was achieved. There was a rapid improvement in function and he returned to work. Vasculopathy of the large intracranial arteries has been described after high dose radiation. It may occur as in this case after moderate dose radiation. There is a correlation with meningioma. There is a possibility that large artery vasculopathy will be present in a proportion of patients irradiated for ALL. The long lag time between irradiation and the development of meningioma may mean that, as survivors of childhood ALL enter their third decade since cure, this tumour may be seen increasingly.

Adult

Influence of nonlinearities on estimates of respiratory mechanics using multilinear regression analysis.

To investigate the influence of nonlinearities on estimates of respiratory mechanics, differing patterns of mechanical ventilation patterns were analyzed from 8 puppies and 14 children. Respiratory mechanics were calculated using multiple linear regression to fit a linear single-compartment model, a volume-dependent single-compartment model (VDSCM), and a flow-dependent single-compartment model. The ratio of the compliance of the last 20% of the dynamic volume-pressure (V-P) curve to the total compliance (C20/C) and the contribution of a volume-dependent elastance to total elastance [%E2 = E2 (VT)/[(E1 + E2)VT], where E1 + E2 is total elastance, E2 is the volume-dependent component, and VT is tidal volume] were used as the indexes of over-distension. By positioning the dynamic loops on the static V-P curves, ventilation patterns were classified as overdistended or nonoverdistended. In the overdistended group, the C20/C was significantly lower (0.71 +/- 0.10 vs. 0.92 +/- 0.16; P < 0.0001) and %E2 was significantly higher (43.4 +/- 15.0 vs. 0.51 +/- 18.02%, P < 0.0001) than in the nonoverdistended group. The mode of ventilation (pressure controlled vs. volume controlled) and the resistive pressures that resulted in widening of the dynamic V-P loop were found to alter C20/C but not %E2. When the respiratory system was overdistended, i.e., ventilated up to the flattened portion of the V-P curve, the VDSCM gave more accurate estimates of respiratory mechanisms. Furthermore, %E2 calculated from VDSCM is a useful parameter for estimating respiratory system overdistension that is not affected by resistive pressures.

Animals

Radiological assessment of the effects of splinting on early hip development: results from a randomised controlled trial of abduction splinting vs sonographic surveillance.

Whilst delayed treatment of fully dislocated hips diagnosed at birth prejudices final outcome, splinting clinically dislocatable hips is controversial as the majority stabilise spontaneously. Early stabilisation may not ensure normal development but even early splinting carries a small risk of avascular necrosis. We report radiological data from 76 newborns with dislocatable hips that were randomised either to immediate splinting or to sonographic surveillance which examines the influence of early splinting on hip development. Epiphyseal maturation (EM), iliac indentation (II) and acetabular angle (AA) were assessed radiographically at 6 months, blind to the treatment group; hips with normal sonograms at birth had greater EM and II and smaller AA. Whilst clinically unstable Graf type 1 and 2A hips were radiologically similar at 6 months, those splinted showed poorer EM and II compared with non-splinted hips. There were no cases of avascular necrosis. Abduction splinting may displace the femoral capital epiphysis medially resulting in poorer iliac indentation. The smaller epiphysis in splinted infants may be secondary to altered blood supply due to increased pressure between the femoral head and acetabulum and increased tension of the adductor muscles in the thigh. These differences were less marked by 1 year. Whether they have any long-term significance requires further study.

Bone Development

Rhabdomyosarcoma associated with familial adenomatous polyposis.

We report a case of a 16 year old girl with orbital rhabdomyosarcoma who during chemotherapy developed bloody diarrhoea. On investigation she was found to have multiple colonic polyps. Cytogenetic analysis has shown a pattern typical of familial adenomatous polyposis. We present a review of the literature concerning the associations of familial adenomatous polyposis. The association of familial adenomatous polyposis with rhabdomyosarcoma has not been previously reported.

Adenomatous Polyposis Coli

Oxygen therapy.

Explore the source record for details and available documents.

Humans

PEEP and CPAP.

Positive end-expiratory pressure (PEEP) maintains airway pressure above atmospheric at the end of expiration, and may be used with mechanical ventilation or spontaneous breathing. CPAP, or continuous positive airway pressure, refers to spontaneous ventilation with a positive airway pressure being maintained throughout the whole respiratory cycle. PEEP/CPAP primarily improves oxygenation by increasing functional residual capacity, and may increase lung compliance and decrease the work of breathing. PEEP/CPAP may be applied using endotracheal tubes, nasal masks or prongs, or face masks or chambers to treat a wide range of adult and paediatric respiratory disorders. Complications associated with their use relate to the pressures applied and include pulmonary barotrauma, decreased cardiac output and raised intracranial pressure.

Airway Resistance

Radiology of fracture-dislocation of the cervical spine during delivery.

Four infants with fracture-dislocation of the cervical spine after traumatic delivery are described. In one patient with tetraparesis and complete dislocation of the cervical spine, transection of the cord at C6 was shown at autopsy. Two patients had fractures through the superior cartilaginous plates of the vertebral body with anterior subluxation of the spine. A fourth patient had a vertical fracture through the body of C5 with tracheal compression secondary to anterior dislocation of the spine. With conservative therapy, these three patients had good clinical recovery with healing and remodeling of the fractured vertebrae.

Birth Injuries

The recovery of pre-ovulatory oocytes using a fixed schedule of ovulation induction and follicle aspiration.

Thirty-two volunteer women, scheduled for laparoscopy, were subjected to a fixed regimen of ovulation induction and ovarian follicle aspiration, following manipulation of the previous menstrual cycle with oral contraceptive pills or norethisterone. This allowed the time of oocyte recovery to be planned several weeks in advance. The recovery rate of mature oocytes (loosely dispersed cumulus) in the patients who had their cycles adjusted with norethisterone was comparable to that in a group of women treated in an embryo-transfer programme who were being individually monitored, although there was evidence from cleavage rates and concentration of sex steroids in follicular fluid that further follicular maturation could have occurred. It is suggested that a modification of this schedule could provide an acceptable recovery rate of pre-ovulatory oocytes for research purposes, and possibly by simplifying the monitoring technique could be applicable to a wider range of patients seeking embryo transfer.

Androgens

Towards safer transport of sick and injured children.

A Paediatric Emergency Transport Service has been operating from the Paediatric Intensive Care Unit of the Royal Children's Hospital, Melbourne, for the last three years. The records of the first 158 patients evacuated have been analysed and are reported. Problems relating to the care of the airway and artificial airway have been the most common. The need for careful pre-transport resuscitation and stabilisation is emphasised. The educational role of a transport service both at the time of initial consultation and at the time of retrieval is stressed.

Aircraft

Death from a snake bite: associated with the supine hypotensive syndrome of pregnancy.

A young pregnant woman, near term, died shortly after being bitten by an immature brown snake (genus Pseudonaja). Analysis of the bitten area suggested that the degree of envenomation was mild, and could not satisfactorily explain her rapid demise. It was concluded that the supine hypotensive syndrome of pregnancy was a contributing factor in her death.

Adult