211 ASSOCIATION OF PLASMA ANTIOXIDANTS AND COGNITIVE OUTCOMES IN NORTHERN IRISH MEN FROM PROSPECTIVE EPIDEMIOLOGICAL STUDY OF MYOCARDIAL INFARCTION (PRIME) STUDY

Background

Oxidative stress and chronic inflammation have been demonstrated to contribute to cognitive decline in older age and the development of neurodegenerative disorders. Antioxidants have been revealed to help mitigate the effects of the damage caused by oxidative stress and inflammation, but their relationship with cognitive decline is not yet fully understood. The aim of this study was to investigate the association between various plasma antioxidant levels and cognitive status in participants from the Prospective Epidemiological Study of Myocardial Infarction (PRIME) study.

Methods

10,600 men were recruited to the PRIME study between 1991-1993 and have been followed up across eleven time points. Baseline health and lifestyle characteristics were assessed, and plasma antioxidants were obtained and quantified. Baseline cognitive status was screened in 2000 using Mini-Mental State Examination (MMSE). Follow up assessment of cognitive status was performed in 2015 with MMSE and Addenbrooke’s Cognitive Examination-Revised (ACE-R) examinations.

Results

2,009 men underwent cognitive assessment in 2000 and 873 men in 2015. At both 2000 and 2015 with the use of the MMSE and ACE-R examinations to assess cognitive status, serum concentration of all the antioxidants except for gamma-tocopherol and lycopene were higher in the men with better cognitive performance at a significant level of p<0.05. Better cognitive performance was associated with more time spent in education and higher level of education achieved at a statistically significant level (p<0.01). Furthermore, those with cognitive impairment were more likely to be older. After adjustments for lifestyle variables with a linear regression model, the only significant variable associated with cognition was time spent in education (B = 0.521, p= 0.02).

Conclusion

The findings suggest that the concentration of plasma antioxidants is associated with cognitive status. Smoking and education, as well as other lifestyle factors were, demonstrated to have an impact on cognitive status.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Estimates and relationships between aboveground and belowground resource exchange surface areas in a Sitka spruce managed forest

Our knowledge of the nature of belowground competition for moisture and nutrients is limited. In this study, we used an earth impedance method to determine the root absorbing area of Sitka spruce (Picea sitchensis (Bong.) Carr.) trees, making measurements in stands of differing density (2-, 4- and 6-m inter-tree spacing). We compared absorbing root area index (RAI(absorbing); based on the impedance measure) with fine root area index (RAI(fine); based on estimates of total surface area of fine roots) and related these results to investment in conductive roots. Root absorbing area was a near-linear function of tree stem diameter at 1.3 m height. At the stand level, RAI(absorbing), which is analogous to and scaled with transpiring leaf area index (maximum stomatal pore area per unit ground area; LAI(transpiring)), increased proportionally with basal area across the three stands. In contrast, RAI(fine) was inversely propotional to basal area. The ratio of RAI(absorbing) to LAI(transpiring) ranged from 7.7 to 17.1, giving an estimate of the relative aboveground versus belowground resource exchange areas. RAI(absorbing) provides a way of characterizing ecosystem functioning as a physiologically meaningful index of belowground absorbing area.

Functional residual capacity and passive compliance measurements after antenatal steroid therapy in preterm infants

Studies in preterm animal models have shown that antenatal corticosteroids enhance lung maturation by improving a variety of physiologic variables, including lung volumes. Changes in lung volume of preterm infants treated with a full course of antenatal steroids have not been investigated. We hypothesized that a full course of antenatal steroids would significantly increase functional residual capacity (FRC) in treated vs. untreated preterm infants. The objective of our study was to compare FRC and respiratory mechanics in steroid treated vs. untreated preterm infants. FRC and passive respiratory mechanics were prospectively studied within 36 hr of life in 20 infants (25-34 weeks of gestation) who had received a full course of antenatal steroids and in 20 matched untreated preterm infants. FRC was measured with the nitrogen washout method, and respiratory mechanics with the single-breath occlusion technique. Preterm infants who received steroids (n = 20; mean birth weight = 1,230 g; gestational age = 28.8 weeks) had a significantly higher FRC (29.5 vs. 19.3 mL/kg; P < 0.001) than untreated infants (n = 20; birth weight = 1,202 g; gestational age = 28.5 weeks). Passive respiratory system compliance was also increased in treated vs. untreated infants (P < 0.05). In conclusion, FRC and passive respiratory system compliance were significantly improved in preterm infants (25-34 weeks gestation) treated with a full course of antenatal steroids, compared to matched untreated infants. Although this study was not randomized, it confirms that antenatal steroids have important effects on pulmonary function that may contribute to a decreased risk of respiratory distress syndrome in treated preterm infants.

Timing of antenatal corticosteroids and neonatal pulmonary mechanics

OBJECTIVE

We sought to compare lung mechanics in infants treated with multiple courses of antenatal corticosteroids with those in matched control infants delivered >7 days from dosing and those of matched untreated infants.

STUDY DESIGN

Eighteen infants who received multiple courses of corticosteroids and were delivered within 7 days of dosing were matched with 18 infants who received 1 course of corticosteroids >7 days before delivery (remote) and 18 untreated infants. Respiratory compliance and functional residual capacity were measured within 36 hours. Differences were compared by analysis of variance.

RESULTS

Infant demographics were similar. Respiratory compliance was higher in the multiple-course group than in the remote or untreated group (P <.02). Functional residual capacity was higher in the multiple-course group than in the untreated group (P <.05) but similar to that found in the remote group.

CONCLUSION

Babies delivered after multiple courses of corticosteroids and within 7 days of dosing demonstrated improved respiratory compliance compared with untreated and remotely treated infants. This suggests that the enzyme system responsible for surfactant production can be repetitively induced despite prior treatment with corticosteroids. The increased functional residual capacity in remotely treated infants may reflect a maturation of lung architecture independent of surfactant production.

(+) 3,4-methylenedioxymethamphetamine ('ecstasy') transiently increases striatal 5-HT1B binding sites without altering 5-HT1B mRNA in rat brain

(+) 3,4-Methylenedioxymethamphetamine (MDMA) is a psychedelic drug of abuse that causes selective degeneration of serotonergic fibers of dorsal raphe neurons that project throughout the forebrain. Previous studies using pharmacological and behavioral approaches suggested that MDMA treatment leads to desensitization of 5-HT1B receptors. We proposed to test whether this occurs by downregulation of 5-HT1B messenger RNA in dorsal raphe, striatum or CA1 hippocampal neurons and/or 5-HT1B binding site density in hippocampus and basal ganglia. In Experiment I, rats were treated with MDMA using several dosing protocols (2.5 or 10 mg kg-1 day-1 s.c. given a single time or twice daily for 4 days). The animals were killed 24 h after the last dose. [3H]-citalopram binding to serotonin transporters in hippocampus was reduced in the high dose protocol, indicating degeneration of forebrain serotonergic fibers. Despite the extensive reduction in serotonergic content, 5-HT1B mRNA did not change from control levels in any region when measured by in situ hybridization. [125I]-Iodocyanopindolol binding to 5-HT1B sites in hippocampus was also not changed. In Experiment II, high dose MDMA had no effect on 5-HT1B mRNA in any brain region either 1 or 14 days after treatment. However, [125I]-iodocyanopindolol binding more than doubled in striatum 1 day after MDMA treatment but returned to control levels by 14 days. This may have been a transient compensation to early neuronal damage caused by MDMA exposure. These results suggest that previously described changes in 5-HT1B function following MDMA treatment involve only posttranscriptional changes in receptor regulation and do not alter 5-HT1B mRNA levels.

Prone positioning decreases episodes of hypoxemia in extremely low birth weight infants (1000 grams or less) with chronic lung disease

Extremely low birth weight infants with chronic lung disease (CLD) have frequent episodes of desaturation (hypoxemia). We quantified oxygenation and episodes of hypoxemia in 55 infants (birth weight < or = 1000 gm) with CLD in the supine versus prone position, for 1-hour time intervals. Oxygen saturation was measured with the Nellcor N-200 pulse oximeter and a computer program. Prone positioning increased oxygen saturation from 92.0% to 94.1% (p < 0.001) and significantly decreased episodes of hypoxemia to oxygen saturation levels of less than 90%, 85%, and 80% (p < 0.001). Our findings support prone positioning for the extremely low birth weight infant with CLD in an intensive care setting.

Pulse oximetry in newborn infants with birth weights of 620 to 4285 grams receiving dopamine and dobutamine

The reliability of pulse oximetry in neonates receiving inotropic drugs because of hypotension and microcirculatory perfusion failure has not been well documented. Signal loss of the pulse oximeter in adult patients receiving dopamine infusions has been reported. To evaluate the relationship between pulse oximeter oxygen saturation (SaO2) and co-oximeter directly measured oxygen saturation, we studied 30 infants in the first 4 days of life (birth weight 620 to 4285 gm, gestational age 26 to 43 weeks) receiving dopamine (30 patients) and dobutamine (10 infants). Infants had normal blood pressures at the time of the study. To minimize motion artifact a Nellcor N-200 (Nellcor Incorporated, Hayward, Calif.) oximeter with electrocardiographic synchronization was used. We compared pulse oximeter values with simultaneous arterial samples analyzed for oxygen saturation with an IL 282 co-oximeter (Instrumentation Laboratory, Inc., Lexington, Mass.). The values were corrected for spuriously elevated carboxyhemoglobin levels and fetal hemoglobin level was quantitatively measured. The partial pressure of oxygen at 90% hemoglobin saturation for each patient was calculated. The dosage of dopamine ranged from 4 to 28 micrograms/kg per minute and the dosage of dobutamine varied from 4 to 24 micrograms/kg per minute. Over a wide range of values for mean blood pressure (23 to 66 mm Hg), partial pressure of oxygen at 90% hemoglobin saturation (43.1 to 70.2 mm Hg), and oxygen saturation (SaO2 80% to 100%), linear regression analysis revealed a close correlation between pulse oximeter SaO2 and co-oximeter SaO2 values (r = 0.83, standard error of the estimate 2.2%, p < 0.0001). Our findings indicate that pulse oximetry can be used reliably for continuous oxygen monitoring in normotensive neonates with an SaO2 of 80% to 100% who are receiving dopamine and dobutamine.

Neonatal pulmonary mechanics and oxygenation after prophylactic amnioinfusion in labor: a randomized clinical trial

OBJECTIVE

Amnioinfusion has been reported to improve the perinatal outcome of pregnancies complicated by decreased amniotic fluid volume, but detailed information on its possible adverse effects on neonatal pulmonary mechanics and oxygenation is not available.

STUDY DESIGN

We evaluated 42 infants with birth weights of 2600 to 4320 g and gestational ages of 36 to 44 weeks, who were born to mothers enrolled in a prospective, randomized trial of amnioinfusion for oligohydramnios in labor. Maternal entry criteria were gestational age 36 weeks or older, estimated fetal weight more than 2500 g, oligohydramnios defined as an amniotic fluid index of 5 cm or less, and a normal fetal heart rate pattern. Evaluation of pulmonary mechanics and oxygen saturation (SaO2) was done with the infants breathing room air between birth and day 3 of life. Transpulmonary pressure, flow, and tidal volume were recorded simultaneously, and pulmonary resistance and lung compliance were calculated. SaO2 was measured for 30 minutes with the Nellcor N-200 oximeter and IBM computer oximetry software.

RESULTS

Evaluation of the data revealed no significant difference between the two groups for tidal volume, lung compliance, pulmonary resistance, or work of breathing. There were no differences between the two groups in the number of desaturation episodes or in percent of desaturations to less than 90%, 85%, or 80% SaO2.

CONCLUSION

Prior studies have shown amnioinfusion to improve perinatal outcome. Our findings demonstrate that amnioinfusion for oligohydramnios in labor does not adversely affect neonatal pulmonary mechanics or oxygenation.

Effects of early dexamethasone therapy on pulmonary mechanics and chronic lung disease in very low birth weight infants: a randomized, controlled trial

OBJECTIVE

To determine the changes in pulmonary mechanics before and during early dexamethasone therapy, and to evaluate the effect of dexamethasone on the duration of mechanical ventilation in very low birth weight (VLBW) ventilator-dependent infants at risk for chronic lung disease (CLD).

METHODS

A prospective randomized trial was conducted. Forty-three patients (birth weight 600 to 1500 g, gestational age 24 to 32 weeks) who failed to be weaned from the respirator at 7 to 14 days of age were enrolled; 23 infants received a 7-day course of dexamethasone (0.5 mg/kg/day intravenously for 3 days, 0.25 mg/kg/day for 3 days, and 0.1 mg/kg/day for 1 day), and 20 patients were in the control group. At similar mean airway pressure (MAP) and fractional inspired oxygen concentration (FiO2), respiratory system mechanics were measured before and on days 2, 5, and 7 of the study. Airway pressure, flow and tidal volume (VT) were recorded and only mechanical breaths were analyzed. Respiratory compliance (Crs) and respiratory resistance (Rrs) were calculated by two factor least mean square analysis.

RESULTS

Eighty-three percent of infants in the dexamethasone group and 90% in the control group received surfactant in the first 24 hours of life. There was a significant increase in Crs and VT in the dexamethasone group as compared with the control group (P < .001). No major changes in Rrs were observed. Dexamethasone therapy significantly decreased FiO2 and MAP P < .001) and facilitated successful weaning from mechanical ventilation. In addition to a shorter duration of mechanical ventilation (P < .01), the occurrence of CLD (FiO2 > 0.21 at 36 weeks of corrected gestational age, chest radiograph changes) was significantly decreased in the dexamethasone group (P < .01). Except for a transient increase in blood pressure and serum glucose, there were no significant differences in infection rates, intraventricular hemorrhage, or retinopathy of prematurity. Thirteen patients in the control group received dexamethasone at a later age.

CONCLUSIONS

Our findings indicate that: 1) early dexamethasone therapy in VLBW infants markedly improves respiratory compliance and tidal volume, reduces FiO2 and MAP requirements, and facilitates extubation in these infants; 2) early dexamethasone therapy reduces the duration of mechanical ventilation and decreases CLD (at 28 days and 36 weeks) in a population of VLBW infants largely treated with surfactant.

Acute pancreatitis associated with acute hepatitis A in a young child

Acute hepatitis A infection is an unusual cause of pancreatitis in adults and has not been reported previously in young children. We describe a 4-year-old girl with acute pancreatitis associated with hepatitis A infection.

Episodes of spontaneous desaturations in infants with chronic lung disease at two different levels of oxygenation

The optimal range of pulse oximeter oxygen saturation (SaO2) for infants with chronic lung disease (CLD) has not been well established. We quantified episodes of spontaneous desaturation, at two different ranges of SaO2. For 1 hr each, we alternatively administered inspired O2 concentrations (FiO2) necessary to maintain an SaO2 of 94-96% or 87-91% to 21 patients (mean birth weight, 865 g; gestational age, 27.3 weeks; postnatal age 40.6 days) with CLD (defined by FiO2 > 0.21 at > or = 28 days and radiographic evidence). SaO2 was monitored with the Nellcor N-200 oximeter and analyzed by a computer program (SatMaster). The percentage of time the infants desaturated to levels of SaO2 < 85 and < 80% revealed significantly fewer spontaneous episodes during the hour of higher baseline SaO2 (P < 0.0002). Comparison of episodes of spontaneous desaturation to SaO2 < 80 and < 85%, lasting 0-15, 16-30, 31-45 sec also showed significant differences between the two levels of SaO2. We conclude that when infants with CLD are maintained at a higher SaO2 they probably experience fewer episodes of spontaneous desaturations, because of less alveolar hypoxia. We believe that attempts at weaning the FiO2 should be tempered with the need of maintaining an adequate SaO2. Therefore, prolonged monitoring of oxygenation in infants with CLD at different levels of SaO2 could be helpful during the weaning process.

Spontaneous desaturations in intubated very low birth weight infants with acute and chronic lung disease

Patients with chronic lung disease (CLD) have frequent episodes of spontaneous desaturations. Utilizing computerized pulse oximetry (CPO) we quantified the frequency and severity of spontaneous desaturations in very low birth weight (VLBW) infants with CLD. Thirty-four studies by CPO were performed in intubated infants for 4 hours; 17 patients (birth weight, 550-980 g; postnatal age 28-85 days) had CLD, and 17 (birth weight, 520-980 g; postnatal age, 1-7 days) had acute lung disease. Oxygen saturation (SaO2) was measured with the Nellcor N-200 oximeter, its serial output (updated once a second) captured by a computer. Pulse rate, pulse amplitude, and heart rate were also monitored continuously. We measured respiratory system mechanics in 23 patients. Tidal volume (VT), respiratory system compliance (Crs), and resistance (Rrs) were obtained by the PeDS system. Spontaneous desaturation to SaO2 less than 90% occurred for 4.5% of the time in acute patients vs. 27.1% of the time in chronic patients (P less than 0.0001); to SaO2 less than 85%, 0.7% vs. 7.6% of the time in acute vs. chronic patients (P less than 0.002); and to SaO2 less than 80%, 0.4% vs. 2.6% of the time in acute vs. CLD patients (P less than 0.05). Rrs was significantly higher in the ventilated patients with CLD (174 cmH2O/L/s) than in the ventilated patients with acute lung disease (94 cmH2O/L/s, P less than 0.0001). The mean Crs values of the two groups were comparable. Our preliminary data indicate that VLBW infants with CLD receiving assisted ventilation have a greater number of spontaneous desaturation episodes, as compared to patients with acute lung disease.