Accelerometer-based method for correcting signal baseline changes caused by motion artifacts in medical near-infrared spectroscopy

In medical near-infrared spectroscopy (NIRS), movements of the subject often cause large step changes in the baselines of the measured light attenuation signals. This prevents comparison of hemoglobin concentration levels before and after movement. We present an accelerometer-based motion artifact removal (ABAMAR) algorithm for correcting such baseline motion artifacts (BMAs). ABAMAR can be easily adapted to various long-term monitoring applications of NIRS. We applied ABAMAR to NIRS data collected in 23 all-night sleep measurements and containing BMAs from involuntary movements during sleep. For reference, three NIRS researchers independently identified BMAs from the data. To determine whether the use of an accelerometer improves BMA detection accuracy, we compared ABAMAR to motion detection based on peaks in the moving standard deviation (SD) of NIRS data. The number of BMAs identified by ABAMAR was similar to the number detected by the humans, and 79% of the artifacts identified by ABAMAR were confirmed by at least two humans. While the moving SD of NIRS data could also be used for motion detection, on average 2 out of the 10 largest SD peaks in NIRS data each night occurred without the presence of movement. Thus, using an accelerometer improves BMA detection accuracy in NIRS.     

Uninstrumented in situ fusion for high-grade childhood and adolescent isthmic spondylolisthesis: long-term outcome

BACKGROUND: Intermediate-term radiographic studies have shown that anterior and circumferential techniques result in high fusion rates in patients with high-grade spondylolisthesis, whereas posterolateral fusion is less successful. We are not aware of any long-term comparative studies in which these three methods have been evaluated with regard to functional outcome, including systematic spinal mobility and trunk strength measurements. METHODS: Sixty-nine of eighty-three consecutive patients with high-grade isthmic spondylolisthesis who underwent posterolateral (twenty-one), anterior (twenty-three), or circumferential (twenty-five) uninstrumented spondylodesis between 1977 and 1991 participated in the study. The average duration of follow-up was 17.2 years. Radiographs that were made preoperatively and at the time of the most recent follow-up were assessed with regard to fusion quality and degenerative changes. Outcome was assessed at the time of the most recent follow-up by independent observers on the basis of a physical examination, spinal mobility and nondynamometric trunk strength measurements, and Oswestry Disability Index scores. RESULTS: The mean preoperative vertebral slip was 61% in the posterolateral fusion group, 63% in the anterior fusion group, and 71% in the circumferential fusion group. The final fusion rate was 86% (eighteen of twenty-one) in the posterolateral fusion group, 100% (twenty-three of twenty-three) in the anterior fusion group, and 96% (twenty-four of twenty-five) in the circumferential fusion group. A decrease in lumbar intervertebral disc height at the first mobile level superior to the fusion was noted in five patients in the posterolateral fusion group, seven patients in the anterior fusion group, and one patient in the circumferential fusion group (p = 0.037). The mean Oswestry Disability Index score was 9.7 for the posterolateral fusion group, 8.9 for the anterior fusion group, and 3.0 for the circumferential fusion group (p = 0.035). Nondynamometric trunk strength measurements corresponded with referential values. Abnormally low lumbar flexion affected the posterolateral and circumferential fusion groups more often than the anterior fusion group (p = 0.0015). The percentage of slip showed inverse correlations with lumbar flexion, lumbar extension, and trunk side-bending. CONCLUSIONS: As assessed on the basis of patient-based outcomes, circumferential in situ fusion provided slightly better long-term results than did posterolateral or anterior in situ fusion. When the radiographic and functional results were combined with the patient-based outcomes, the overall differences between the three groups were small.     

Partial remission indicates poor functioning and a high level of psychiatric symptoms: a 3-phase 6-year follow-up study on major depression

Patients with depression in partial remission are at high risk of relapse, but factors associated with being in this outcome group are not well known. We conducted a clinical survey to examine the course of major depression in 87 patients during a follow-up period of 6 years. Beck Depression Inventory (BDI) scores indicated the outcome of depression, i.e. remission, partial remission or fully symptomatic, at 6, 12 and 24 months and after 6 years. The prevalence of partial remission varied from 16% to 23% at different follow-ups. All symptom and functioning scale scores indicated at every assessment that the partial depression group managed better than those in the fully symptomatic group, but worse than those in remission. Partial remission was associated with a significant impairment in psychosocial functioning and a high level of symptoms throughout the follow-up. The partial remission group must be recognized and actively treated.     

New mini-extracorporeal circulation system (ECC.O) is a safe technique in coronary surgery

OBJECTIVES: Cardiopulmonary bypass (CPB) is known to cause the systemic inflammatory reaction after cardiac surgery. New coated and closed loop circuit systems may reduce this inflammation response and improve the surgical outcome. This study was designed to evaluate the safety and efficacy of the mini-extracorporeal circulation system (ECC.O) in CABG patients. DESIGN: Forty patients undergoing elective coronary surgery were randomized into two groups, the ECC.O group and the standard CPB group. Routine hemodynamic monitoring and biochemical measurements were registered according to the hospital practice. RESULTS: The clinical outcome of the patients was similar in both groups. There were no significant differences between the groups in the duration of intubation following surgery, the length of intensive care unit-stay or the total hospital stay. The haemoglobin level was significantly higher (p=0.0069) during and after the perfusion in the ECC.O group. CONCLUSIONS: The ECC.O system can be safely used in CABG patients and it maintains haemoglobin level better than conventional CPB.     

Exercise-related hypoglycaemia induces QTc-interval prolongation in individuals with type 1 diabetes

Aims

To investigate changes in cardiac repolarisation during exercise-related hypoglycaemia compared to hypoglycaemia induced at rest in people with type 1 diabetes.

Material and methods

In a randomised crossover study, 15 men with type 1 diabetes underwent two separate hyperinsulinaemic euglycaemic-hypoglycaemic clamp experiments during Holter-ECG monitoring. One experiment included a bout of moderate-intensity cycling exercise (60 min) along with declining plasma glucose (PG; Clamp-exercise). In the other experiment, hypoglycaemia was induced with the participants at rest (Clamp-rest). We studied QTc interval, T-peak to T-end (Tpe) interval and hormonal responses during three steady-state phases: (i) baseline (PG 4.0–8.0 mmol/L); (ii) hypoglycaemic phase (PG <3.0 mmol/L); and (iii) recovery phase (PG 4.0–8.0 mmol/L).

Results

Both QTc interval and Tpe interval increased significantly from baseline during the hypoglycaemic phase but with no significant difference between test days. These changes were accompanied by an increase in plasma adrenaline and a decrease in plasma potassium on both days. During the recovery phase, ΔQTc interval was longer during Clamp-rest compared to Clamp-exercise, whereas ΔTpe interval remained similar on the two test days.

Conclusions

We found that both exercise-related hypoglycaemia and hypoglycaemia induced at rest can cause QTc-interval prolongation and Tpe-interval prolongation in people with type 1 diabetes. Thus, both scenarios may increase susceptibility to ventricular arrhythmias.     

Circulating cell-free DNA in health and disease — the relationship to health behaviours,ageing phenotypes and metabolomics

GeroScience - Circulating cell-free DNA (cf-DNA) has emerged as a promising biomarker of ageing, tissue damage and cellular stress. However, less is known about health behaviours, ageing phenotypes...     

Glycaemia and cardiac arrhythmias in people with type 1 diabetes: A prospective observational study

Aim

To investigate the impact of hypoglycaemia, hyperglycaemia and glycaemic variability on arrhythmia susceptibility in people with type 1 diabetes.

Materials and Methods

Thirty adults with type 1 diabetes were included in a 12-month observational exploratory study. Daytime and night-time incident rate ratios (IRRs) of arrhythmias were determined for hypoglycaemia (interstitial glucose [IG] <3.9 mmol/L), hyperglycaemia (IG >10.0 mmol/L) and glycaemic variability (standard deviation and coefficient of variation).

Results

Hypoglycaemia was not associated with an increased risk of arrhythmias compared with euglycaemia and hyperglycaemia combined (IG ≥ 3.9 mmol/L). However, during daytime, a trend of increased risk of arrhythmias was observed when comparing time spent in hypoglycaemia with euglycaemia (IRR 1.08 [95% CI: 0.99-1.18] per 5 minutes). Furthermore, during daytime, both the occurrence and time spent in hyperglycaemia were associated with an increased risk of arrhythmias compared with euglycaemia (IRR 2.03 [95% CI: 1.21-3.40] and IRR 1.07 [95% CI: 1.02-1.13] per 5 minutes, respectively). Night-time hypoglycaemia and hyperglycaemia were not associated with the risk of arrhythmias. Increased glycaemic variability was not associated with an increased risk of arrhythmias during daytime, whereas a reduced risk was observed during night-time.

Conclusions

Acute hypoglycaemia and hyperglycaemia during daytime may increase the risk of arrhythmias in individuals with type 1 diabetes. However, no such associations were found during night-time, indicating diurnal differences in arrhythmia susceptibility.