Measuring cerebrovascular autoregulation in preterm infants using near-infrared spectroscopy: an overview of the literature

Introduction: The preterm born infant’s ability to regulate its cerebral blood flow (CBF) is crucial in preventing secondary ischemic and hemorrhagic damage in the developing brain. The relationship between arterial blood pressure (ABP) and CBF estimates, such as regional cerebral oxygenation as measured by near-infrared spectroscopy (NIRS), is an attractive option for continuous non-invasive assessment of cerebrovascular autoregulation. Areas covered: The authors performed a literature search to provide an overview of the current literature on various current clinical practices and methods to measure cerebrovascular autoregulation in the preterm infant by NIRS. The authors focused on various aspects: Characteristics of patient cohorts, surrogate measures for cerebral perfusion pressure, NIRS devices and their accompanying parameters, definitions for impaired cerebrovascular autoregulation, methods of measurements and clinical implications. Expert commentary: Autoregulation research in preterm infants has reported many methods for measuring autoregulation using different mathematical models, signal processing and data requirements. At present, it remains unclear which NIRS signals and algorithms should be used that result in the most accurate and clinically relevant assessment of cerebrovascular autoregulation. Future studies should focus on optimizing strategies for cerebrovascular autoregulation assessment in preterm infants in order to develop autoregulation-based cerebral perfusion treatment strategies

Non-AIDS defining cancers in the D:A:D Study-time trends and predictors of survival : a cohort study

BACKGROUND:Non-AIDS defining cancers (NADC) are an important cause of morbidity and mortality in HIV-positive individuals. Using data from a large international cohort of HIV-positive individuals, we described the incidence of NADC from 2004-2010, and described subsequent mortality and predictors of these.METHODS:Individuals were followed from 1st January 2004/enrolment in study, until the earliest of a new NADC, 1st February 2010, death or six months after the patient's last visit. Incidence rates were estimated for each year of follow-up, overall and stratified by gender, age and mode of HIV acquisition. Cumulative risk of mortality following NADC diagnosis was summarised using Kaplan-Meier methods, with follow-up for these analyses from the date of NADC diagnosis until the patient's death, 1st February 2010 or 6 months after the patient's last visit. Factors associated with mortality following NADC diagnosis were identified using multivariable Cox proportional hazards regression.RESULTS:Over 176,775 person-years (PY), 880 (2.1%) patients developed a new NADC (incidence: 4.98/1000PY [95% confidence interval 4.65, 5.31]). Over a third of these patients (327, 37.2%) had died by 1st February 2010. Time trends for lung cancer, anal cancer and Hodgkin's lymphoma were broadly consistent. Kaplan-Meier cumulative mortality estimates at 1, 3 and 5 years after NADC diagnosis were 28.2% [95% CI 25.1-31.2], 42.0% [38.2-45.8] and 47.3% [42.4-52.2], respectively. Significant predictors of poorer survival after diagnosis of NADC were lung cancer (compared to other cancer types), male gender, non-white ethnicity, and smoking status. Later year of diagnosis and higher CD4 count at NADC diagnosis were associated with improved survival. The incidence of NADC remained stable over the period 2004-2010 in this large observational cohort.CONCLUSIONS:The prognosis after diagnosis of NADC, in particular lung cancer and disseminated cancer, is poor but has improved somewhat over time. Modifiable risk factors, such as smoking and low CD4 counts, were associated with mortality following a diagnosis of NADC

Maternal antihypertensive drugs may influence cerebral oxygen extraction in preterm infants during the first days after birth

Objective: To determine whether maternal antihypertensive drugs influenced cerebral oxygenation in preterm infants during the first days after birth. Methods: We included 49 preterm infants (median gestational age 30.3 weeks, (range 26.0-31.9), birth weight 1250 g (560-2250)). Regional cerebral oxygen saturation (r(c)SO(2)) was measured by near-infrared spectroscopy on postnatal days 1, 2, 3, 4 and 5. Fractional tissue oxygen extraction (FTOE) was calculated using r(c)SO(2) and arterial oxygen saturation (SpO(2)) values:(SpO(2) - rcSO(2))/SpO(2). Results: Nine mothers were treated with labetalol and/or MgSO4 during pregnancy, three mothers with labetalol, MgSO4 and nifedipine, and 19 mothers with nifedipine only. Eighteen infants served as controls. Multivariate linear regression analysis showed that exposure to labetalol and/or MgSO4 during pregnancy decreased FTOE on day 1 after birth, while nifedipine did not. Conclusions: Treating pregnant women with labetalol and/or MgSO4 may influence cerebral oxygen extraction in their offspring shortly after birth

Placental pathology is associated with illness severity in preterm infants in the first twenty-four hours after birth

Background: Placental pathology is associated with long-term neurological morbidity. Little is known about the association of placental pathology and illness severity directly after birth in preterm infants. Objective: To determine the association between placental pathology and illness severity in preterm infants during the first 24 h after birth. Study design: Placentas of 40 preterm infants, born after singleton pregnancies (gestational age 25.4-31.7 weeks, birth weight 560-2250 g) were assessed for histopathology. Illness severity was measured using the Score of Neonatal Acute Physiology Perinatal Extension (SNAPPE). A high SNAPPE reflects high illness severity. Results: Examination of the 40 placentas revealed: pathology consistent with maternal vascular under-perfusion (MVU) (n = 24), ascending intrauterine infection (AIUI) (n = 17), villitis of unknown aetiology (VUE) (n = 6), foetal thrombotic vasculopathy (FTV) (n = 6), elevated nucleated red blood cells (NRBCs) (n = 6), and chronic deciduitis (n = 10). SNAKE ranged from 1 to 53 (median 10). Infants with elevated NRBCs had a higher SNAPPE than infants without elevated NRBCs (median 30 vs. 10,p = 0.014). The same was found for the presence of FTV (median 30 vs. 10, p = 0.019). No relation existed between SNAPPE and the other placental pathologies. Conclusions: Elevated NRBCs and FTV were associated with higher illness severity during the first 24 h after birth in preterm infants. Ascending intrauterine infection was not associated with high illness severity. (C) 2011 Elsevier Ireland Ltd. All rights reserved

Reversal reaction in borderline leprosy is associated with a polarized shift to type 1-like Mycobacterium leprae T cell reactivity in lesional skin. A follow-up study

Borderline leprosy patients often undergo acute changes in immune reactivity that manifest as reversal reaction (RR) in the course of the disease. RR is associated with an exacerbated local delayed-type cellular immune response to Mycobacterium leprae and is responsible for severe tissue damage. We investigated whether RR episodes are associated with a change in T cell subsets in the lesional skin with regard to their cytokine secretion profiles. M. leprae-responsive T cell lines and thereafter T cell clones (TCC) were generated from the lesional skin of seven untreated borderline leprosy patients (with or without RR) and again from three of these patients experiencing RR during treatment. The phenotypes of the M. leprae-responsive TCC were either CD4+, CD8+, CD4-/CD8+/TCR gammadelta+, or CD4-/CD8-/TCR gammadelta+, although most of them were CD4+. Regardless of the clinical status of the untreated patients, a major subset of the M. leprae-responsive TCC was type 0-like and produced both IFN-gamma and IL-4. Interestingly, in all three patients who experienced a (re)occurrence of RR during treatment after the first analysis, a clear shift to polarized IFN-gamma production by the M. leprae-responsive TCC (type 1-like) was observed. This shift in T cell subsets was also reflected in the observed decrease in serum IgG and IgM levels of the same patients during RR. These finding indicate that CD4+ M. leprae-responsive T cells with a polarized type 1-like phenotype might be responsible for the immune-mediated tissue damage occurring during R

Positional OSA part 2:retrospective cohort analysis with a new classification system (APOC)

Background. In Part 1 of this two-part article, the Amsterdam Positional Obstructive Sleep Apnoea Classification (APOC) was recently introduced, a classification system aimed at facilitating the identification of suitable candidates for positional therapy (PT): patients who will benefit from a clinically significant improvement of their obstructive sleep apnoea (OSA) with PT. APOC was developed with new generation PT devices in mind rather than conventional PT (tennis ball technique). New generation PT can be defined as a well-tolerated device which prevents a patient from adopting the worst sleeping position (WSP) without negatively influencing sleep efficiency, as objectified by a full night polysomnography (PSG). PT is rapidly gaining momentum in the scope of OSA treatment. The objective of this manuscript is to measure the prevalence of position-dependent obstructive sleep apnoea (POSA) according to the APOC, in a consecutive series of patients referred for PSG as well as an investigation of associations between POSA and certain patient characteristics. Methods. We performed a retrospective, single-centre cohort study including a consecutive series of patients who underwent a PSG during the period of April 2010 until October 2010. Results. Within this OSA-cohort (n = 253), a prevalence of POSA of 69 % when applying APOC is measured, compared to 64 % when applying Cartwright’s classification. An inverse relation between POSA and BMI was observed, likewise between POSA and apnoea hypopnoea index (AHI). Conclusion. We are of opinion that APOC is a suitable tool to identify patients who will or will not benefit from PT, thus resulting in more cost-efficient treatment

Prenatal tobacco exposure influences cerebral oxygenation in preterm infants

Aim: Our aim was to determine the influence of prenatal tobacco exposure on regional cerebral tissue oxygen saturation (r(c)SO(2)) and fractional tissue oxygen extraction (FTOE) in preterm infants. We hypothesized that as a result of vasoconstriction caused by prenatal tobacco exposure r(c)SO(2) would be lower and FTOE would be higher during the first days after birth in infants exposed to tobacco during pregnancy. Methods: Sixty preterms were included in this prospective, observational cohort study (median gestational age 29.9 weeks, range 26.0-31.8, median birth weight 1248 g, range 615-2250). Fourteen infants had been exposed to tobacco during pregnancy. All mothers smoked more than five cigarettes a day till delivery. We measured r(c)SO(2) and transcutaneous arterial oxygen saturation (tcSaO(2)) in all infants on days 1-5,8, and 15. FTOE was calculated: FTOE = (tcSaO(2) - r(c)SO(2))/tcSaO(2). Results: In preterm infants exposed to tobacco during pregnancy, r(c)SO(2) was lower during days 1,2, and 8 after birth, median 73% versus 81%. 73% versus 80% and 71% versus 78% respectively. FTOE was higher during days 1 and 8 after birth, median 0.24 versus 0.15 and 0.26 versus 0.19 respectively. On the second day. FTOE tended to be higher. 0.18 versus 0.14. Conclusions: During the first two days and day 8 after birth cerebral oxygen saturation is lower and oxygen extraction higher in preterm infants following prenatal tobacco exposure. Our data suggest that prenatal tobacco exposure may have an effect on cerebral oxygenation of the infant. (C) 2011 Elsevier Ireland Ltd. All rights reserved