Maternal pre-pregnancy body mass index and risk of preterm birth: a collaboration using large routine health datasets.

BACKGROUND: Preterm birth (PTB) is a leading cause of child morbidity and mortality. Evidence suggests an increased risk with both maternal underweight and obesity, with some studies suggesting underweight might be a greater factor in spontaneous PTB (SPTB) and that the relationship might vary by parity. Previous studies have largely explored established body mass index (BMI) categories. Our aim was to compare associations of maternal pre-pregnancy BMI with any PTB, SPTB and medically indicated PTB (MPTB) among nulliparous and parous women across populations with differing characteristics, and to identify the optimal BMI with lowest risk for these outcomes. METHODS: We used three UK datasets, two USA datasets and one each from South Australia, Norway and Denmark, together including just under 29 million pregnancies resulting in a live birth or stillbirth after 24 completed weeks gestation. Fractional polynomial multivariable logistic regression was used to examine the relationship of maternal BMI with any PTB, SPTB and MPTB, among nulliparous and parous women separately. The results were combined using a random effects meta-analysis. The estimated BMI at which risk was lowest was calculated via differentiation and a 95% confidence interval (CI) obtained using bootstrapping. RESULTS: We found non-linear associations between BMI and all three outcomes, across all datasets. The adjusted risk of any PTB and MPTB was elevated at both low and high BMIs, whereas the risk of SPTB was increased at lower levels of BMI but remained low or increased only slightly with higher BMI. In the meta-analysed data, the lowest risk of any PTB was at a BMI of 22.5 kg/m2 (95% CI 21.5, 23.5) among nulliparous women and 25.9 kg/m2 (95% CI 24.1, 31.7) among multiparous women, with values of 20.4 kg/m2 (20.0, 21.1) and 22.2 kg/m2 (21.1, 24.3), respectively, for MPTB; for SPTB, the risk remained roughly largely constant above a BMI of around 25-30 kg/m2 regardless of parity. CONCLUSIONS: Consistency of findings across different populations, despite differences between them in terms of the time period covered, the BMI distribution, missing data and control for key confounders, suggests that severe under- and overweight may play a role in PTB risk.

Evaluation of an intervention to reduce tidal volumes in ventilated ICU patients.

BACKGROUND: There is considerable evidence that the use of tidal volumes <6 ml kg(-1) predicted body weight (PBW) reduces mortality in mechanically ventilated patients. We evaluated the effectiveness of using a large screen displaying delivered tidal volume in ml kg(-1) (PBW) for reducing tidal volumes. METHODS: We assessed the intervention in two 6-month periods. A qualitative study was undertaken after the intervention period to examine staff interaction with the intervention. The study was conducted in a mixed medical and surgical intensive care unit at University Hospitals Bristol, UK. Consecutive patients requiring controlled mechanical ventilation for more than 1 h were included. Alerts were triggered when tidal volume breached predetermined targets and these alerts were visible to ICU clinicians in real time. RESULTS: A total of 199 patients with 7640 h of data were observed during the control time period and 249 patients with 10 656 h of data were observed in the intervention period. Time spent with tidal volumes <6 ml kg(-1) PBW increased from 17.5 to 28.6% of the period of controlled mechanical ventilation. Time spent with a tidal volume <8 ml kg(-1) PBW increased from 60.6 to 73.9%. The screens were acceptable to staff and stimulated an increase in attendance of clinicians at the bedside to adjust ventilators. CONCLUSIONS: Changing the format of data and displaying it with real-time alerts reduced delivered tidal volumes. Configuring information in a format more likely to result in desired outcomes has the potential to improve the translation of evidence into practice.

Systematic review and meta-analysis of the effect of intraoperative α2-adrenergic agonists on postoperative behaviour in children.

Undergoing general anaesthesia is distressing for children, with up to two-thirds demonstrating abnormal behaviours after their procedure, such as emergence delirium (ED) and post-hospitalization behaviour change. The aim of this systematic review was to determine the effect of intraoperative i.v. α2-adrenergic agonists on postoperative behaviour in children. We included published full-text reports of randomized controlled trials involving children who received i.v. clonidine or dexmedetomidine after induction of general anaesthesia, who were assessed for postoperative behavioural disturbance. After screening of references identified by the search strategy, a data collection form was developed and piloted. Data extraction was performed by one reviewer and checked by a second. Twelve randomized trials met the inclusion criteria. Ten studies (n=669) reported dichotomous data that were included in the pooled analysis of α2-adrenergic agonists vs placebo. There was strong evidence that i.v. α2-adrenergic agonists reduced postoperative ED (overall summary odds ratio 0.28, 95% confidence interval 0.19-0.40, P<0.001). No studies examined post-hospitalization negative behaviour changes. There was evidence that α2-adrenergic agonists prolonged time in the recovery room. No adverse haemodynamic events were reported in any arm of any study. This meta-analysis provides evidence that intraoperative i.v. α2-adrenergic agonists reduce the incidence of emergency delirium in children. The prolongation of time in recovery is unlikely to be clinically relevant. The absence of data regarding the effect on post-hospitalization behavioural changes provides an opportunity for future research.

The influence of distress on knowledge transfer for men newly diagnosed with prostate cancer.

The purpose of this inquiry was to evaluate the efficacy of prostate cancer education sessions. Implementation of 3-h patient educational sessions was intended to provide men newly diagnosed with localized prostate cancer, who face difficult and complex decisions, information about potential treatment options. Fifty-seven men completed the distress thermometer assessment before the education session to assess baseline levels of distress. Seven of the men were interviewed post-educational session to determine the degree of knowledge transfer from the session. This study explored the efficacy of the patients' learning experience using an interpretive phenomenological research approach. Resulting data revealed that these patients, as adult learners, were distressed and that, despite the availability of pertinent medical content, the subject material was not learned as intended or readily understood. The conclusion drawn from this preliminary applied educational research study was that the education model used was less than efficacious at ensuring that sufficient knowledge transfer was achieved for medical treatment decision-making processes. These findings suggest a need for future research to explore the application of adult learning theories and approaches that may offer enhanced knowledge translation and transfer for prostate cancer education programs.

Failed endotracheal intubation and adverse outcomes among extremely low birth weight infants.

OBJECTIVE: To quantify the importance of successful endotracheal intubation on the first attempt among extremely low birth weight (ELBW) infants who require resuscitation after delivery. STUDY DESIGN: A retrospective chart review was conducted for all ELBW infants ⩽1000 g born between January 2007 and May 2014 at a level IV neonatal intensive care unit. Infants were included if intubation was attempted during the first 5 min of life or if intubation was attempted during the first 10 min of life with heart rate <100. The primary outcome was death or neurodevelopmental impairment. The association between successful intubation on the first attempt and the primary outcome was assessed using multivariable logistic regression with adjustment for birth weight, gestational age, gender and antenatal steroids. RESULTS: The study sample included 88 ELBW infants. Forty percent were intubated on the first attempt and 60% required multiple intubation attempts. Death or neurodevelopmental impairment occurred in 29% of infants intubated on the first attempt, compared with 53% of infants that required multiple attempts, adjusted odds ratio 0.4 (95% confidence interval 0.1 to 1.0), P<0.05. CONCLUSION: Successful intubation on the first attempt is associated with improved neurodevelopmental outcomes among ELBW infants. This study confirms the importance of rapid establishment of a stable airway in ELBW infants requiring resuscitation after birth and has implications for personnel selection and role assignment in the delivery room.

Variations in T1 and T2 relaxation times of normal appearing white matter and lesions in multiple sclerosis.

OBJECTIVE: To investigate the variation in T1 and T2 relaxation times of normal appearing white matter (NAWM) and lesions in multiple sclerosis (MS) throughout the brain. BACKGROUND: The magnetic resonance imaging (MRI) sequence fast FLAIR (fluid attenuated inversion recovery) has demonstrated overall increased lesion detection when compared to conventional or fast spin echo (FSE) but fewer lesions in the posterior fossa and spinal cord. The reasons for this are unknown, but may be due to variations in the T1 and T2 relaxation times within NAWM and MS lesions. METHOD: Ten patients and 10 controls underwent MRI of the brain which involved FSE, fast FLAIR and the measurement of T1 and T2 relaxation times. RESULTS: Of 151 lesions analysed (22 infra-tentorial, 129 supra-tentorial), eight were missed by the fast FLAIR sequence. T1 and T2 relaxation times in normal controls were longer in the infra-tentorial, than supra-tentorial, region. Patient NAWM relaxation times were prolonged compared with control values in both regions. Lesions demonstrated longer relaxation times than either control white matter or patient NAWM in both regions, however this difference was less marked infra-tentorially. The eight posterior fossa lesions not visible on the fast FLAIR sequence were characterised by short T1 and T2 relaxation times which overlapped with the patient NAWM for both T1 and T2 and with control values for T2 relaxation times. CONCLUSION: Both lesion and NAWM relaxation time characteristics vary throughout the brain. The T1 and T2 relaxation times of infra-tentorial lesions are closer to the relaxation times of local NAWM than supra-tentorial lesions, resulting in reduced contrast between posterior fossa lesions and the background NAWM. Consequently the characteristics of some lesions overlap with those of NAWM resulting in reduced conspicuity. By utilising this information, it may be possible to optimise fast FLAIR sequences to improve infra-tentorial lesion detection.

Water diffusion in the human hippocampus in epilepsy.

The hippocampus plays a central role in the generation and propagation of seizures in patients with complex partial seizures. Hippocampal sclerosis (HS) is a common structural abnormality in patients with refractory epilepsy. The aim of this study was to quantify diffusion in the hippocampus in patients with epilepsy to evaluate the diffusion changes associated with HS. We scanned 20 subjects (14 patients and 6 controls) with a 1.5T magnetic resonance (MR) system using a cardiac-gated, navigated spin-echo diffusion-weighted sequence. Hippocampal ADC measurements were performed on maps of the ADC measured in three orthogonal directions labeled x, y, and z. The mean ADC (ADCav) and an anisotropy index (AI) were calculated. Hippocampi which fulfilled the MR criteria for HS had a higher ADCav (p < 0.001) and a lower AI (p=0.04) than normal appearing hippocampi in patients and hippocampi in controls. These results imply a loss of structural organization in sclerotic hippocampi and an expansion of the extracellular space. Quantitative measurements of diffusion can be used as an independent parameter for the identification and characterization of abnormal hippocampi in epilepsy.

Upright dynamic MR defaecating proctography in an open configuration MR system.

We describe our experience evaluating an MR proctography technique using an open 0.5 T MR system. Evacuation of a gadolinium-containing rectal contrast agent was dynamically imaged in the upright position using a fast gradient echo sequence. Anatomical and functional abnormalities were documented. Results from 40 patients who underwent this technique are reported. The method is proposed as an alternative to conventional fluoroscopic proctography.

Magnetic resonance guided general surgery.

Image guided surgery can be defined as the intraoperative use of a radiologicai technique to give the surgeon information not available from direct inspection or palpation of the surgical field. This information may then be used to change the course of an operative procedure. Magnetic resonance (MR) imaging has the potential to be the most useful radiologicai technique in the developing field of image guided surgery.

The Cataract National Dataset electronic multi-centre audit of 55,567 operations: risk indicators for monocular visual acuity outcomes.

AIMS: To report risk factors for visual acuity (VA) improvement and harm following cataract surgery using electronically collected multi-centre data conforming to the Cataract National Dataset (CND). METHODS: Routinely collected anonymised data were remotely extracted from the electronic patient record systems of 12 participating NHS Trusts undertaking cataract surgery. Following data checks and cleaning, analyses were performed to identify risk indicators for: (1) a good acuity outcome (VA 6/12 or better), (2) the pre- to postoperative change in VA, and (3) VA loss (doubling or worse of the visual angle). RESULTS: In all, 406 surgeons from 12 NHS Trusts submitted data on 55,567 cataract operations. Preoperative VA was known for 55,528 (99.9%) and postoperative VA outcome for 40,758 (73.3%) operations. Important adverse preoperative risk indicators found in at least 2 of the 3 analyses included older age (3), short axial length (3), any ocular comorbidity (3), age-related macular degeneration (2), diabetic retinopathy (3), amblyopia (2), corneal pathology (2), previous vitrectomy (2), and posterior capsule rupture (PCR) during surgery (3). PCR was the only potentially modifiable adverse risk indicator and was powerfully associated with VA loss (OR=5.74). CONCLUSION: Routinely collected electronic data conforming to the CND provide sufficient detail for identification and quantification of preoperative risk indicators for VA outcomes of cataract surgery. The majority of risk indicators are intrinsic to the patient or their eye, with a notable exception being PCR during surgery.

Regional changes in hippocampal T2 relaxation and volume: a quantitative magnetic resonance imaging study of hippocampal sclerosis.

OBJECTIVE: The principal MRI features of hippocampal sclerosis are volume loss and increased T2 weighted signal intensity. Minor and localised abnormalities may be overlooked without careful quantitation. Hippocampal T2 relaxation time (HT2) can be quantified, but previously has only been measured on a few thick coronal slices with interslice gaps. In this study HT2 was measured along the entire length of the hippocampus on contiguous slices and used, with quantitative measures of hippocampal volume (HV) and distribution of atrophy, to better define the range of hippocampal sclerosis. METHODS: Thirty patients with temporal lobe epilepsy, 10 patients with extratemporal localisation related epilepsy and extratemporal lesions, and 20 control subjects were studied using MRI T2 relaxometry and volumetry. RESULTS: In controls and patients, HT2 was higher in the anterior than the posterior hippocampus. Using HV, morphometric, and HT2 data, patients with temporal lobe epilepsy were classified as unilateral diffuse hippocampal sclerosis (n=16), unilateral focal (n=6), bilaterally affected (n=6), and normal (n=2). In patients with unilateral hippocampal sclerosis, the anterior hippocampus was always affected. In three patients with normal HV, HT2 measurements disclosed unilateral focal abnormalities that corresponded to the EEG lateralisation of epileptic activity. Patients with bilateral hippocampal involvement had an earlier onset of epilepsy than patients with unilateral hippocampal sclerosis. CONCLUSIONS: Measurement of regional abnormalities of HT2 along the length of the hippocampus provides further refinement to the MRI assessment of the hippocampi in patients with temporal lobe epilepsy and is complementary to volumetric and morphological data.