Dural ectasia in Marfan's syndrome: magnetic resonance imaging appearances and anaesthetic experience of three deliveries.

Neuraxial anaesthetic techniques are considered useful to minimise haemodynamic stress during labour. In Marfan's syndrome, connective tissue abnormalities not only affect the thoracic aorta but also predispose to dural ectasia. A dural ectatic sac may cause difficulties with neuraxial analgesia and anaesthesia. We discuss magnetic resonance imaging appearances and anaesthetic experience of three deliveries in a parturient with stable echocardiographic findings. We consider that epidural analgesia and anaesthesia are a safe and pragmatic solution for labour and delivery. Lumbo-sacral magnetic resonance imaging at presentation will define dural ectasia and assist in management.

Dystrophia myotonica: combined spinal-epidural anaesthesia for caesarean section.

Patients with dystrophia myotonica requiring caesarean section pose significant problems for the anaesthetist. This report describes the successful use of a combined spinal-epidural technique for anaesthesia and postoperative analgesia in such a patient.

Significant digits: foundations, myths and utilization.

Scientific text books, journal articles, and all types of other sources of scientific information frequently give certain recommendations and/or make statements of presumed fact concerning the issue of significant digits in scientific computation. Most of these "well-known" facts concerning significance in computation are false. This article discusses the folklore of significant digits, debunks the common cliches, illustrates the actual behavior of computational significance in a typical scenario, and makes recommendations concerning these matters.

Comparison of four subarachnoid solutions in a needle-through-needle technique for elective caesarean section.

We have used both spinal and extradural anaesthesia with a 26-gauge, long spinal needle through a 16-gauge Tuohy needle for elective Caesarean section. Four different subarachnoid solutions of bupivacaine were compared: 0.5% heavy bupivacaine alone, or with adrenaline, fentanyl or adrenaline and fentanyl. The incidence of complications and time of regression of the sensory block were analysed. The technique is recommended because it allows rapid onset of anaesthesia and the advantages of an extradural catheter. The subarachnoid solution of choice was 0.5% heavy bupivacaine 12.5 mg with fentanyl 10 micrograms.

Estimates of radiation dose and health risks to the United States population following the Chernobyl nuclear plant accident.

Estimates of both individual and collective doses received by the United States population following the Chernobyl accident have been made by using the data obtained from the U.S. Environmental Protection Agency's Environmental Radiation Ambient Monitoring System. Radionuclides associated with the debris first were measured in precipitation and surface air particulates at Portland, OR and Olympia, WA on 5 May 1986. Iodine-131 was the most consistently measured nuclide in all media, although several Cs and Ru isotopes also were observed. Strontium and any actinides notably were absent from the samples at the lower level of detection. The highest calculated individual-organ dose due to intake during May and June 1986 was 0.52 mSv to the infant thyroid in the state of Washington. This was predominantly (98%) from the ingestion of milk. The maximum U.S. collective dose equivalent to any organ was calculated to be 3,300 person-Sv to the thyroid. Risk estimates project three excess lung cancer deaths and an additional four deaths due to cancers of thyroid, breast and leukemia in the U.S. population over the next 45 y from exposure during the May-June 1986 interval. The only long-lived radionuclide measured in milk samples following the accident was 137Cs. We estimate 20 excess fatalities from the ingestion of 137Cs in milk during all subsequent years, with six of these due to lung cancer and the majority of the remainder distributed approximately equally among cancers of the thyroid, breast, liver and leukemia. A total of 100 excess fatalities from all dietary components was estimated. Because of the uncertainty of risk estimates from data such as those available for this study, all calculated values carry a range of uncertainty from a minimum of one-half the calculated value to a maximum of two times the calculated value. The estimated excess fatalities given above may be compared with corresponding projected cancer mortality from all other causes: 41,000 fatalities from thyroid cancer and 3,800,000 fatalities from lung cancer are estimated to occur within the U.S. population during the next 45 y.

Bright light phase shifts the human melatonin rhythm during the Antarctic winter.

In most species daily and seasonal changes in the light-dark cycle are the most important synchronisers (zeitgebers) of daily and seasonal rhythms. In humans only bright light (2500 lux) appears to be an effective circadian zeitgeber. Seasonal effects of light on human physiology have not been investigated. We have exploited the low intensity illumination of the Antarctic winter to investigate the effects of bright- or dim-light treatment for an hour in the morning and in the evening (a 'skeleton' 12.5-h day) for 6 weeks on the plasma melatonin rhythm, together with mood and a number of behavioural variables. In parallel seasonal changes in melatonin were observed. Melatonin is known to convey daylength information in photoperiodic seasonal breeders through characteristics of its night-time secretion profile. Bright-, but not dim-, light treatment in winter induced a marked phase advance of the melatonin rhythm, similar to that found in the summer, without marked effect on the other variables. Thus at least one human seasonal change appears to be light-dependent.