Cambridge hybrid closed-loop algorithm in children and adolescents with type 1 diabetes: a multicentre 6-month randomised controlled trial

BACKGROUND

Closed-loop insulin delivery systems have the potential to address suboptimal glucose control in children and adolescents with type 1 diabetes. We compared safety and efficacy of the Cambridge hybrid closed-loop algorithm with usual care over 6 months in this population.

METHODS

In a multicentre, multinational, parallel randomised controlled trial, participants aged 6-18 years using insulin pump therapy were recruited at seven UK and five US paediatric diabetes centres. Key inclusion criteria were diagnosis of type 1 diabetes for at least 12 months, insulin pump therapy for at least 3 months, and screening HbA1c levels between 53 and 86 mmol/mol (7·0-10·0%). Using block randomisation and central randomisation software, we randomly assigned participants to either closed-loop insulin delivery (closed-loop group) or to usual care with insulin pump therapy (control group) for 6 months. Randomisation was stratified at each centre by local baseline HbA1c. The Cambridge closed-loop algorithm running on a smartphone was used with either (1) a modified Medtronic 640G pump, Medtronic Guardian 3 sensor, and Medtronic prototype phone enclosure (FlorenceM configuration), or (2) a Sooil Dana RS pump and Dexcom G6 sensor (CamAPS FX configuration). The primary endpoint was change in HbA1c at 6 months combining data from both configurations. The primary analysis was done in all randomised patients (intention to treat). Trial registration ClinicalTrials.gov, NCT02925299.

FINDINGS

Of 147 people initially screened, 133 participants (mean age 13·0 years [SD 2·8]; 57% female, 43% male) were randomly assigned to either the closed-loop group (n=65) or the control group (n=68). Mean baseline HbA1c was 8·2% (SD 0·7) in the closed-loop group and 8·3% (0·7) in the control group. At 6 months, HbA1c was lower in the closed-loop group than in the control group (between-group difference -3·5 mmol/mol (95% CI -6·5 to -0·5 [-0·32 percentage points, -0·59 to -0·04]; p=0·023). Closed-loop usage was low with FlorenceM due to failing phone enclosures (median 40% [IQR 26-53]), but consistently high with CamAPS FX (93% [88-96]), impacting efficacy. A total of 155 adverse events occurred after randomisation (67 in the closed-loop group, 88 in the control group), including seven severe hypoglycaemia events (four in the closed-loop group, three in the control group), two diabetic ketoacidosis events (both in the closed-loop group), and two non-treatment-related serious adverse events. There were 23 reportable hyperglycaemia events (11 in the closed-loop group, 12 in the control group), which did not meet criteria for diabetic ketoacidosis.

INTERPRETATION

The Cambridge hybrid closed-loop algorithm had an acceptable safety profile, and improved glycaemic control in children and adolescents with type 1 diabetes. To ensure optimal efficacy of the closed-loop system, usage needs to be consistently high, as demonstrated with CamAPS FX.

FUNDING

National Institute of Diabetes and Digestive and Kidney Diseases.

Clinical outcomes and programming strategies of implantable cardioverter defibrillator (ICD) devices during childhood in hypertrophic cardiomyopathy: a UK national cohort study

Background

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM). ICDs have been shown to be effective at terminating malignant ventricular arrhythmias but at the expense of a high incidence of complications. The optimal device and programming strategies to reduce complications in this patient group are unknown.

Purpose

To describe the programming strategies and clinical outcomes of ICD implantation in childhood HCM.

Methods

Anonymised, non-invasive clinical data were collected from a retrospective, longitudinal multi-centre cohort of children (<16 years) with HCM (n=687) and an ICD in-situ from the United Kingdom.

Results

96 patients (61 male (64%), 6 non-sarcomeric (6%)) underwent ICD implantation at a median age 14yr (IQR 11–16, range 3–16) and weight 52.3 kg (IQR 34.8–63.1). Indication for ICD was primary prevention in 72 (75%). 82 (85%) had an endovascular system, 3 (3%) epicardial and 11 (12%) subcutaneous system. 61 patients (74%) were receiving one or more cardioactive medications at implantation [B blockers n=66, 70%, disopyramide n=14, 15%, amiodarone n=7, 7%, calcium channel blocker n=7, 9%, other n=5, 6%]. Programming practices varied: all had VF therapies activated (median 220bpm, IQR 212–230); 70 (73%) had a VT zone programmed (median rate 187 bpm, SD 20.9), of which 26 (27%) had therapies activated. 50 patients (61%) had antitachycardia pacing (ATP) activated. Over a median follow up of 53.6 months (IQR 27.3,108.4), 4 patients (4.2%) died following arrhythmic events despite a functioning device. 25 patients had 53 appropriate therapies (ICD shock n=47, ATP n=8), incidence rate 5.22 (95% CI 3.5–7.8). On univariable analysis, secondary prevention indication for ICD implantation was the only predictor of therapy [16 (64%) vs 8 (11.3%), p value <0.001]. 8 (8.3%) patients had 9 inappropriate therapies (ICD shock n=4, ATP n=5), incidence rate 1.37 (95% CI 0.65–2.8), caused by T wave oversensing (n=2), lead migration (n=1), supraventricular tachycardia (n=1). Device complications were seen in 30 patients (31%), including lead complications (n=16) and infection (n=10). No clinical characteristics predicted time to inappropriate therapy or lead complication.

Conclusions

In a contemporary cohort of children with HCM, the incidence of inappropriate therapies is lower than previously reported, yet complication rates remain higher than reported in adult patients. No clinical, device or programming strategies were associated with inappropriate therapies or lead complications.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): British Heart Foundation

A STUDY OF THE IMAGE QUALITY OF COMPUTED TOMOGRAPHY ADAPTIVE STATISTICAL ITERATIVE RECONSTRUCTED BRAIN IMAGES USING SUBJECTIVE AND OBJECTIVE METHODS

The recent reintroduction of iterative reconstruction in computed tomography has facilitated the realisation of major dose saving. The aim of this article was to investigate the possibility of achieving further savings at a site with well-established Adaptive Statistical iterative Reconstruction (ASiR™) (GE Healthcare) brain protocols. An adult patient study was conducted with observers making visual grading assessments using image quality criteria, which were compared with the frequency domain metrics, noise power spectrum and modulation transfer function. Subjective image quality equivalency was found in the 40-70% ASiR™ range, leading to the proposal of ranges for the objective metrics defining acceptable image quality. Based on the findings of both the patient-based and objective studies of the ASiR™/tube-current combinations tested, 60%/305 mA was found to fall within all, but one, of these ranges. Therefore, it is recommended that an ASiR™ level of 60%, with a noise index of 12.20, is a viable alternative to the currently used protocol featuring a 40% ASiR™ level and a noise index of 11.20, potentially representing a 16% dose saving.

Clinical implications of machine-probe combinations on obstetric ultrasound measurements used in pregnancy dating

OBJECTIVE

To investigate the effect of use of different machine-probe combinations on measurement variability and to assess how this variability impacts on accuracy of pregnancy dating.

METHODS

Sixteen different ultrasound machine-probe combinations were used for lateral measurement of targets spaced 10 and 40 mm apart and axial measurement of targets spaced 10 and 50 mm apart in an ultrasound phantom, and differences between the measured and true values were determined. The mean of the 40-mm lateral measurements was used to estimate gestational age using standard obstetric dating tables for crown-rump length (CRL) and femur length (FL) and the mean of the 50-mm axial measurements was used to estimate gestational age using the obstetric dating tables for biparietal diameter (BPD).

RESULTS

As absolute measurements became larger, differences observed using different machine-probe combinations exceeded those due to intraobserver variability. Maximum dating differences for first-trimester CRL of 2 days (based on a measured CRL range of 39-42 mm), second-trimester BPD of 4 days (based on a measured BPD range of 49-52 mm) and FL of 9 days (based on a measured FL range of 39-42 mm) were observed when measurements were transposed to the equivalent gestational age using standard charts.

CONCLUSION

Differences between measured and true values of biometric measurements reflect both machine-probe and intraobserver variability. Incremental first-trimester CRL growth with time is rapid, but second-trimester FL growth is much less so, leaving this lateral measurement more prone to both observer and machine-probe errors. The only axial growth measurement commonly performed is BPD where the measurement differences were intermediate between those of CRL and FL. The differences that can be ascribed to different equipment combinations are in many cases greater than those expected in clinical practice and are of potential importance in determining how fetal biometry is used for dating pregnancies.

Thermographic imaging during nasal peanut challenge may be useful in the diagnosis of peanut allergy

BACKGROUND

Double-blinded challenges are widely used for diagnosing food allergy but are time-consuming and cause severe reactions. Outcome relies on subjective interpretation of symptoms, which leads to variations in outcome between observers. Facial thermography combined with nasal peanut challenge was evaluated as a novel objective indicator of clinical allergy.

METHODS

Sixteen children with positive blinded peanut challenge underwent nasal challenge with 10 μg peanut protein or placebo. Mean skin temperatures were recorded from the mouth and nose using infrared thermography over 18 min.

RESULTS

The area under curve of nasal skin temperature was significantly elevated after peanut vs placebo (18.2 vs 4.8°Cmin). The maximum increase in temperature was also significantly greater after peanut: mean difference +0.9°C.

CONCLUSION

This feasibility study shows thermography can detect inflammation caused by nasal challenges whilst employing one thousand-fold less peanut than an oral challenge. This novel technique could be developed to provide a rapid, safe and objective clinical allergy test.

Heat distribution and heat transport in bone during radiofrequency catheter ablation

BACKGROUND

To assess the feasibility of percutaneous radiofrequency ablation in large bone tumours, the heat distribution in cortical bone and marrow around inserted electrodes was measured.

METHODS

Fresh bovine cadaver tibial bones were locally heated through drill holes for a maximum of half an hour using water-cooled single radiofrequency electrodes (Radionics Instruments Inc) by pulsed energy. Temperatures were measured in the marrow canal as well as in cortical bone by thermocouples at various distances from the inserted probes.

RESULTS

Perpendicular to the probe, hyperthermia of more than 50 degrees C could be created in bone marrow in a sphere of approximately 3 cm, and of approximately 1 cm in cortical bone.

CONCLUSION

As irreversible cellular damage can be expected when increasing the temperature to 50 degrees C for a duration of 6 min, this method may be effective for the minimal invasive ablation of neoplasms within human bone in cigar-shaped regions of approximately 3-cm diameter.