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Background Controversy exists whether different continuous positive airway pressure (CPAP) weaning methods infl uence time to wean off CPAP, CPAP duration, oxygen duration, Bronchopulmonary Dysplasia (BPD) or length of admission. Aims In a multicentre randomised controlled trial, the authors have primarily compared CPAP weaning methods impact on time to wean off CPAP and CPAP duration and secondarily their effect on oxygen duration, BPD and time of admission. Methods Between April 2006 and October 2009, 177 infants <30 weeks gestational age (GA) who fulfi lled stability criteria on CPAP were randomised to one of the three CPAP weaning methods (M). M1: Taken 'OFF' CPAP with the view to stay 'OFF'. M2: Cycled on and off CPAP with incremental time 'OFF'. M3: As with M2, cycled on and off CPAP but during 'OFF' periods were supported by 2 mm nasal cannula at a fl ow of 0.5 l/min. Results Based on intention to treat analysis, there was no signifi cant difference in mean GA or birthweight between the groups (27.1±1.4, 26.9±1.6 and 27.3±1.5 (weeks±1SD) and 988±247, 987±249 and 1015±257 (grams±1SD), respectively). Primary outcomes showed M1 produced a signifi cantly shorter time to wean from CPAP (11.3±0.8, 16.8±1.0, 19.4±1.3 (days±1SE) p<0.0001, respectively) and CPAP duration (24.4±0.1, 38.6±0.1, 30.5±0.1 (days±1SE) p<0.0001, respectively). All the secondary outcomes were signifi cantly shorter with M1, (oxygen duration: 24.1±1.5, 45.8±2.2, 34.1±2.0 (days±1SE) p<0.0001, BPD: 7/56 (12.5%), 29/69 (42%), 10/52 (19%) p=0.011 and length of admission: 58.5±0.1, 73.8±0.1 69.5±0.1 (days±1SE) p<0.0001, respectively). Conclusion Method 1 signifi cantly shortens CPAP weaning time, CPAP duration, oxygen duration, BPD and admission time. INTRODUCTIONContinuous positive airway pressure (CPAP) has been used in preterm babies as a mode of respiratory support since the 1970s and is now used in most NICUs. [1][2][3][4][5] Subsequently, it has been shown that CPAP may reduce the need for invasive intubation and ventilation, reduce apnoea of prematurity and postextubation atelectasis. Early use of CPAP reduces the incidence of Bronchopulmonary Dysplasia (BPD (defi ned as an oxygen requirement at 36 weeks corrected gestational age)) and the need for home oxygen. [5][6][7][8][9][10][11] There are several ways of delivering CPAP including head chamber, facemask, nasal prongs and endotracheal tubes. [5][6][7][8] Research and clinical experience have shown that nasal CPAP with nasal prongs is the most effi cient way of delivering continuous distending pressure (CDP) to the alveoli. [5][6][7][8] Once infants are stabilised and breathing adequately on CPAP, the CPAP is usually weaned off gradually. 6 7 Controversy continues over the best method of weaning CPAP and is often approached in an 'ad hoc' manner. 5 7 12-14 Four trials have compared methods of weaning CPAP and its impact on CPAP duration. [15][16][17][18] The fi rst trial studied the changes in respiratory parameters in infants <34 weeks gestational age (GA) requiring CPAP. ...

Summary.-This paper reviews data relating to obstetric radiography from the Oxford Survey of Childhood Cancers, i.e. for deaths in Britain from 1953 to 1967.Some 8513 cases were traced and used in the analyses, together with an equal number of matched controls. The relative risk estimate (1.47 overall) does not vary significantly between different tumour groups, for different ages at death, nor between sexes. Other epidemiological factors-sibship position, maternal age, social class, region of residence and maternal morbidity-are analysed and show varying degrees of association, but not sufficient to " explain " the observed risk in terms of a selection effect. The dependence of the risk on the number of films exposed is highly significant and adequately described by a linear relationship. The timing of and reason for the exposure are also examined. Analysis of the risk by year of birth shows a pattern of steadily declining risk for both solid and haematopoietic tumours; this may be partly attributable to lower radiation doses per film exposed but is also due to the smaller numbers of films used. A consequence may well be that the risk-always of small clinical significance-would become virtually undetectable in future investigations.