indicate that attitudes among the medical profession and patients are changing.There has been much discussion about clinical trials and informed consent,46 and, though we believe that informed consent is mandatory, we accept that a proportion of patients do not enter trials because they may dislike the idea of a random decision being made about treatment or because they refuse or request one part of the random option offered. A further group of patients are excluded because they do not fulfil the entry criteria for the trial, and this group may be larger than forecast at the time the trial was planned. These factors may be the reason why accrual to the Scottish breast conservation trial has been slower than anticipated. The planned total intake was 900 patients, and after four years 420 patients had been entered.In conclusion more than half of the patients thought initially to be suitable for conservation were excluded from our trials and one third of the remainder refused to take part. Those planning prospective clinical trials should therefore take into account the loss of patients through ineligibility and refusal when predicting the accrual rate and overall duration of any proposed trial and the possible effects of this selection on conclusions drawn from the results. Design-A study of all infants dying suddenly and unexpectedly and of two controls matched for age and date with each index case. The parents of control infants were interviewed within 72 hours of the index infant's death. Information was collected on bedding, sleeping position, heating, and recent signs of illness for index and control infants.Setting-A defined geographical area comprising most of the county of Avon and part of Somerset.Subjects-72 Infants who had died suddenly and unexpectedly (of whom 67 had died from the sudden infant death syndrome) and 144 control infants.Results-Compared with the control infants the infants who had died from the sudden infant death syndrome were more likely to have been sleeping prone (relative risk 8-8; 95% confidence interval 7.0 to 11-0; p<0-001), to have been more heavily wrapped (relative risk 1-14 per tog above 8 tog; 1-03 to 1-28; p<005), and to have had the heating on all night (relative risk 2-7; 1-4 to 5.2; p<0-01). These differences were less pronounced in the younger infants (less than 70 days) than the older ones. The risk of sudden unexpected death among infants older than 70 days, nursed prone, and with clothing and bedding of total thermal resistance greater than 10 tog was increased by factors of 15-1 (2.6 to 89.6) and 25-2 (3.7 to 169-0) respectively compared with the risk in

ABSTRACX. We have investigated the effect of changing environmental temperature on metabolic rate, sleep state, and water loss in a longitudinal study of 22 lightly clothed babies from 2 d to 3 mo of age. Studies were performed in a modified barometric plethysmograph while recording sleep state, oxygen consumption, and skin and axillary temperatures. Oxygen consumption was higher in rapid eye movement sleep than in quiet sleep at all ages and varied widely between infants at each temperature. Within the first week, there was a 19% rise in oxygen consumption on cooling to 19-22OC during rapid eye movement sleep and a 6% rise during quiet sleep. The medim duration of quiet sleep periods was reduced from 17 to 12 min on cooling within the first week. No such change was seen at 1, 2, and 3 mo. Axillary temperature was reduced at 3 mo during cooling. This may be a part of normal patterns of change in temperature during sleep, unrelated to cooling. At each age, total evaporative water loss fell linearly with falling environmental temperature both within and below the temperature range at which metabolic rate was minimal. The evaporative water losses were greater than expected and suggested that sweating was occurring, both at temperatures at which metabolic rate was minimal and at those at which it was increased. The metabolic response to cooling and the process of sweating appear to be in dynamic equilibrium across this temperature range. Thus, it was not possible to define a temperature range over which both metabolic rate and evaporative water loss were at minimum values. REM, rapid eye movement sleepThe relationship between environmental temperature and V02 has been previously studied in term infants (1-3). The lower end of the thermoneutral range has been defined and is lower at 3 wk of age than at 1 d, in both naked and cot-nursed babies, and might be assumed to fall further with increasing age (4). The effect of sleep state on metabolic rate has been studied both in adults (5) and in babies within the first week at thermoneutral and cooler temperatures (6-8). In all these studies, metabolic rate was higher in REM. However, little information is available on the relationship between sleep state and environmental temperature, or on thermoneutrality, at older ages in infancy.We have investigated the effect of mild cold stress on metabolism and water loss (both respiratory and transcutaneous) during both REM and QS in infants from the first week to 3 mo of age. MATERIALS AND METHODSTwenty-two normal, healthy infants, free from known adverse risk factors were selected. All the infants were born at term (gestational age from 37.5 to 42 wk) to healthy mothers and had a median birth weight of 3.44 kg (range 3.1-4.74 kg). None experienced significant perinatal problems or had any major illnesses during the first 3 mo. Each infant was studied once during the first week (median age 49 h, range 16-143 h) and on one to three further occasions, at 1, 2, and 3 mo. Polygraphic recordings of sleep state and respiration were pe...

In summary, there is evidence that developmental changes in respiratory control and in thermoregulation have effects upon each other. Theoretically, such effects could give rise to failure of the respiratory system and there is some circumstantial evidence to support the concept that on occasions such interactions may be of importance in sudden unexpected death in infancy. Future research in this area should focus on the nature of the interactions between thermoregulation and respiration, and on the effects of infection and infection-related mediators on those interactions.

In a longitudinal, population based study, overnight temperature recordings were made in the bedrooms of 152 babies aged 3-18 weeks and the insulation provided by their bedclothing was assessed. Outdoor temperatures for the study nights were also available.Parents applied more insulation on colder nights with lower bedroom temperatures than on warmer nights (mean 8.5 tog at 15°C minimum bedroom temperature falling to 4-0 tog at 25°C). For a particular temperature they also applied 2 tog more insulation in winter than in summer.The amounts ofbedclothing used in the home were compared with insulation levels predicted to achieve thermoneutrality over a similar range of environmental temperature from heat balance studies in young infants. They corresponded closely.The The first was a descriptive study of what was actually happening in our community. It was undertaken by measuring bedroom temperatures in babies' homes and by discovering the type and amount of clothing and bedding that babies were sleeping under, throughout the year and longitudinally over the first few months of life. In contrast the second study was carried out in a laboratory environment using a series of heat balance measurements on a smaller number of babies to determine how much insulation was required to achieve thermoneutrality over a range of environmental temperatures comparable to those in the home. Methods COMMUNITY METHODS

Objective-To determine whether signs of illness reported by parents can be used to identify babies at risk from the sudden infant death syndrome.Design-A two year prospective case-controlled study based in a geographically defined area.Setting-Four health districts in Avon and north Somerset.Subjects-Babies who had died suddenly and unexpectedly aged between 1 week and 2 years (index babies) and two control babies for each index baby selected from the same health visitor's list and matched for age, time of year of the interview, and area of residence.Main outcome measures-Major and minor signs of illness during two weeks before the index babies' death, or before the interview for control babies, and consultations with the general practitioner during the same period.Results Conclusion-Major and minor signs of illness are neither a sensitive nor a specific indicator of sudden