The association between infant salivary cortisol and parental presence in the neonatal intensive care unit during and after COVID-19 visitation restrictions: A cross-sectional study

OBJECTIVES

Parent-infant interaction in the neonatal intensive care unit (NICU) promotes health and reduces infant stress. During the COVID-19 pandemic, however, NICUs restricted parent-infant interaction to reduce viral transmission. This study examined the potential relationship between pandemic visitation restrictions, parental presence and infant stress as measured by salivary cortisol.

METHODS

A two-NICU cross-sectional study of infants with gestational age (GA) 23-41 weeks, both during (n = 34) and after (n = 38) visitation restrictions. We analysed parental presence with and without visitation restrictions. The relationship between infant salivary cortisol and self-reported parental NICU presence in hours per day was analysed using Pearson's r. A linear regression analysis included potential confounders, including GA and proxies for infant morbidity. The unstandardised B coefficient described the expected change in log-transformed salivary cortisol per unit change in each predictor variable.

RESULTS

Included infants had a mean (standard deviation) GA of 31(5) weeks. Both maternal and paternal NICU presence was lower with versus without visitation restrictions (both p ≤0.05). Log-transformed infant salivary cortisol correlated negatively with hours of parental presence (r = -0.40, p = .01). In the linear regression, GA (B = -0.03, p = .02) and central venous lines (B = 0.23, p = .04) contributed to the variance in salivary cortisol in addition to parental presence (B = -0.04 p = .04).

CONCLUSION

COVID-19-related visitation restrictions reduced NICU parent-infant interaction and may have increased infant stress. Low GA and central venous lines were associated with higher salivary cortisol. The interaction between immaturity, morbidity and parental presence was not within the scope of this study and merits further investigation.

Microbial DNA extraction of high-host content and low biomass samples: Optimized protocol for nasopharynx metagenomic studies

Introduction

Low microbial biomass and high human DNA content in nasopharyngeal aspirate samples hinder comprehensive characterization of microbiota and resistome. We obtained samples from premature infants, a group with increased risk of developing respiratory disorders and infections, and consequently frequent exposure to antibiotics. Our aim was to devise an optimal protocol for handling nasopharyngeal aspirate samples from premature infants, focusing on host DNA depletion and microbiome and resistome characterization.

Methods

Three depletion and three DNA extraction protocols were compared, using RT-PCR and whole metagenome sequencing to determine the efficiency of human DNA removal, taxonomic profiling and assignment of antibiotic resistance genes. Protocols were tested using mock communities, as well as pooled and individual patient samples.

Results

The only extraction protocol to retrieve the expected DNA yield from mock community samples was based on a lytic method to improve Gram positive recovery (MasterPure™). Host DNA content in non-depleted aliquots from pooled patient samples was 99%. Only samples depleted with MolYsis™ showed satisfactory, but varied reduction in host DNA content, in both pooled and individual patient samples, allowing for microbiome and resistome characterisation (host DNA content from 15% to 98%). Other depletion protocols either retrieved too low total DNA yields, preventing further analysis, or failed to reduce host DNA content. By using Mol_MasterPure protocol on aliquots from pooled patient samples, we increased the number of bacterial reads by 7.6 to 1,725.8-fold compared to non-depleted reference samples. PCR results were indicative of achieved microbial enrichment. Individual patient samples processed with Mol_MasterPure protocol varied greatly in total DNA yield, host DNA content (from 40% to 98%), species and antibiotic resistance gene richness.

Discussion

Despite high human DNA and low microbial biomass content in nasopharynx aspirates of preterm infants, we were able to reduce host DNA content to levels compatible with downstream shotgun metagenomic analysis, including bacterial species identification and coverage of antibiotic resistance genes. Whole metagenomic sequencing of microbes colonizing the nasopharynx may contribute to explaining the possible role of airway microbiota in respiratory conditions and reveal carriage of antibiotic resistance genes.

Increased breastfeeding; an educational exchange program between India and Norway improving newborn health in a low- and middle-income hospital population

Background

The purpose of the project was to improve newborn health in neonatal care units in a low resource area with high neonatal mortality, predominantly by better nutrition and educational exchange of health care workers.

Method

A fourfold program to make human milk production and distribution feasible and desirable. 1 Education to enlighten health care workers and parents to the excellence of human milk. 2 Lactation counselling to address the various challenges of breastfeeding. 3 Improving infants´ general condition. 4 Infrastructure alterations in the hospital. A collaboration between hospitals in India and Norway.

Results

The number of infants receiving human milk increased pronouncedly. Systematic, professional lactation counselling, the establishment of a milk bank, and empowerment of nurses was perceived as the most important factors.

Conclusions

It is possible to greatly improve nutrition and the quality of newborn care in low/middle income settings by optimising human resources. Viable improvements can be obtained by long-term health partnership, by involving all hierarchal levels and applying locally developed customized methods.

Mode of Neonatal Delivery Influences the Nutrient Composition of Human Milk: Results From a Multicenter European Cohort of Lactating Women

Background

The effect of the mode of neonatal delivery (cesarean or vaginal) on the nutrient composition of human milk (HM) has rarely been studied. Given the increasing prevalence of cesarean section (C-section) globally, understanding the impact of C-section vs. vaginal delivery on the nutrient composition of HM is fundamental when HM is the preferred source of infant food during the first 4 postnatal months.

Objective

This study aimed to evaluate the association between mode of delivery and nutrient composition of HM in the first 4 months of life.

Design

Milk samples were obtained from 317 healthy lactating mothers as part of an exploratory analyses within a multicenter European longitudinal cohort (ATLAS cohort) to study the HM composition, and its potential association with the mode of delivery. We employed traditional mixed models to study individual nutrient associations adjusted for mother’s country, infant birth weight, parity, and gestational age, and complemented it, for the first time, with a multidimensional data analyses approach (non-negative tensor factorization, NTF) to examine holistically how patterns of multiple nutrients and changes over time are associated with the delivery mode.

Results

Over the first 4 months, nutrient profiles in the milk of mothers who delivered vaginally (n = 237) showed significantly higher levels of palmitoleic acid (16:1n-7), stearic acid (18:0), oleic acid (18:1n-9), arachidic acid (20:0), alpha-linolenic acid (18:3n-3), eicosapentaenoic acid (20:5n-3), docosahexenoic acid (22:6n-3), erucic acid (22:1n-9), monounsaturated fatty acids (MUFA)%, calcium, and phosphorus, whereas the ratios of arachidonic acid/docosahexaenoic acid (ARA/DHA) and n-6/n-3, as well as polyunsaturated fatty acids (PUFA)% were higher in milk from women who had C-sections, in the unadjusted analyses (p < 0.05 for all), but did not retain significance when adjusted for confounders in the mixed models. Using a complementary multidimension data analyses approach (NTF), we show few similar patterns wherein a group of mothers with a high density of C-sections showed increased values for PUFA%, n-6/n-3, and ARA/DHA ratios, but decreased values of MUFA%, 20:1n-9, iodine, and fucosyl-sialyl-lacto-N-tetraose 2 during the first 4 months of lactation.

Conclusion

Our data provide preliminary insights on differences in concentrations of several HM nutrients (predominantly fatty acids) among women who delivered via C-section. Although these effects tend to disappear after adjustment for confounders, given the similar patterns observed using two different data analytical approaches, these preliminary findings warrant further confirmation and additional insight on the biological and clinical effects related to such differences early in life.

Analysis of dietary patterns and nutritional adequacy in lactating women: a multicentre European cohort (ATLAS study)

Eating habits of lactating women can influence the nutrient composition of human milk, which in turn influences nutrient intake of breastfed infants. The aim of the present study was to identify food patterns and nutritional adequacy among lactating women in Europe. Data from a multicentre European longitudinal cohort (ATLAS study) were analysed to identify dietary patterns using cluster analysis. Dietary information from 180 lactating women was obtained using 3-d food diaries over the first 4 months of lactation. Four dietary patterns were identified: 'vege-oils', 'fish-poultry', 'confectionery-salads' and 'mixed dishes'. Nutrition adequacy was not significantly different between clusters, but the 'vege-oils' cluster tended to yield the highest nutrition adequacy measured by Mean Adequacy Ratio. Compared with European dietary reference values (DRVs) for lactating women, women in all clusters had inadequate intakes of energy, pantothenic acid, folate, vitamin C, vitamin A, vitamin D, zinc, iodine, potassium and linoleic acid. Adequate intake for fibre and α-linolenic acid was only achieved in the 'vege-oils' cluster. Overall, fat intake was above DRVs. The present study showed that various dietary patterns do not adequately supply all nutrients, indicating a need to promote overall healthy dietary habits for European lactating women.

Antibiotic Stewardship in Premature Infants: A Systematic Review

INTRODUCTION

Antibiotic treatment in premature infants is often empirically prescribed, and practice varies widely among otherwise comparable neonatal intensive care units. Unnecessary and prolonged antibiotic treatment is documented in numerous studies. Recent research shows serious side effects and suggests long-term adverse health effects in prematurely born infants exposed to antibiotics in early life. One preventive measure to reduce unnecessary antibiotic exposure is implementation of antibiotic stewardship programs. Our objective was to review the literature on implemented antibiotic stewardship programs including premature infants with gestational age ≤34 weeks.

METHODS

Six academic databases (PubMed [Medline], McMaster PLUS, Cochrane Database of Systematic Reviews, UpToDate, Cochrane Central Register of Controlled Trials, and National Institute for Health and Care Excellence) were systematically searched. PRISMA guidelines were applied.

RESULTS

The search retrieved 1,212 titles of which 12 fitted inclusion criteria (11 observational studies and 1 randomized clinical trial). Included articles were critically appraised. We grouped the articles according to common area of implemented stewardship actions: (1) focus on reducing initiation of antibiotic therapy, (2) focus on shortening duration of antibiotic therapy, (3) various organizational stewardship implementations. The heterogeneity of cohort composition, of implemented actions and of outcome measures made meta-analysis inappropriate. We provide an overview of the reduction in antibiotic use achieved.

CONCLUSION

Antibiotic stewardship programs can be effective for premature newborns especially when multifactorial and tailored to this population, focusing on reducing initiation or on shortening the duration of antibiotic therapy. Programs without specific measures were less effective.

Subclinical Mastitis in a European Multicenter Cohort: Prevalence, Impact on Human Milk (HM) Composition, and Association with Infant HM Intake and Growth

Background: Subclinical mastitis (SCM) is an inflammatory condition of the mammary gland. We examined the effects of SCM on human milk (HM) composition, infant growth, and HM intake in a mother–infant cohort from seven European countries. Methods: HM samples were obtained from 305 mothers at 2, 17, 30, 60, 90, and 120 days postpartum. SCM status was assessed using HM Sodium (Na): Potassium (K) ratio >0.6. Levels of different macro- and micronutrients were analyzed in HM. Results: SCM prevalence in the first month of lactation was 35.4%. Mean gestational age at delivery was lower and birth by C-section higher in SCM mothers (p ≤ 0.001). HM concentrations of lactose, DHA, linolenic acid, calcium, and phosphorous (p < 0.05 for all) was lower, while total protein, alpha-lactalbumin, lactoferrin, albumin, arachidonic acid to DHA ratio, n-6 to n-3 ratio and minerals (iron, selenium, manganese, zinc, and copper) were higher (p < 0.001 for all) in mothers with SCM. There were no differences in infant growth and HM intake between non-SCM and SCM groups. Conclusion: We document, for the first time, in a large European standardized and longitudinal study, a high prevalence of SCM in early lactation and demonstrate that SCM is associated with significant changes in the macro- and micronutrient composition of HM. Future studies exploring the relation of SCM with breastfeeding behaviors and developmental outcomes are warranted.

Angiotensin II receptor antagonists against migraine in pregnancy: fatal outcome

A pregnant young woman with a severe migraine is prescribed candesartan, an angiotensin II type 1 receptor antagonist (AT II antagonists). This has a positive effect-except for severe maldevelopment of her fetus. There is an increase in the use of the fetotoxic drugs, AT II antagonists and angiotensin-converting enzyme inhibitors, as prophylactic treatment of migraines, in addition to their use as hypertensives.

Oxidative stress markers and antioxidant status after oral iron supplementation to very low birth weight infants

OBJECTIVE

To evaluate whether our current practice of giving iron 18 mg daily to 6-week-old infants with very low birth weight (VLBW) was associated with increased oxidative stress markers or decreased antioxidant status.

STUDY DESIGN

The study was a prospective observational study of 21 healthy VLBW infants (born at gestational age <32 weeks, birth weight <1500 g). Blood and urine were sampled twice before starting iron supplementation at 6 weeks postnatal age and after 1 week of iron supplementation at age 7 weeks. Urine 8-isoprostane was analyzed by gas chromatography-mass spectrometry and plasma total hydroperoxides were measured. Antioxidant status was assessed by ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), ferric-reducing ability of plasma, and plasma glutathione.

RESULTS

After 1 week of iron supplementation, no significant changes in urine 8-isoprostane or plasma total hydroperoxides were seen, and plasma antioxidants were largely unchanged.

CONCLUSIONS

Markers of oxidative stress in urine and plasma antioxidant status in healthy VLBW infants fed human milk remained unchanged after high-dose oral iron supplementation.

Lidocaine pharmacokinetics and toxicity in newborn pigs

In newborn infants suffering from perinatal asphyxia seizures, lidocaine (LD) has proved to be an effective anticonvulsant. At high concentrations, however, LD can itself cause convulsions. The convulsive concentration of LD (LD(conv)) varies among species. The aim of this study was to describe LD pharmacokinetics and to define the LD(conv) in awake newborn pigs. Eighteen Land race newborn pigs aged 12-60 h, weight 1.0-2.5 kg, were enrolled. LD, 2 mg/kg intravenous (IV) bolus, (n = 11) was given to estimate pharmacokinetic variables. Continuous LD infusion 2 mg x kg(-1) x min(-1) IV (n = 5) and repeated bolus doses of 15 mg/kg (n = 4) were given until electroencephalogram-confirmed seizures appeared. After the bolus injection, the elimination half-life for LD was 0.87-5.44 h. Increasing plasma concentration (LD(pl)) during infusion resulted in sedation after 5-10 min and in shivering, nystagmus, neck extension, tonic-clonic seizures at LD(conv) of 40.6 +/- 12.7 mg/L (mean +/- SD). The unbound LD(pl) at seizures was 4.4 +/- 2.4 mg/L. Younger animals convulsed at higher LD(conv) (r2 = 0.85). LD pharmacokinetics in newborn pigs were found to be dose-dependent at high plasma concentrations. At lower plasma concentrations, LD pharmacokinetics appeared to be linear. The central nervous system is the primary target for the toxic effect of LD in awake newborn pigs. LD neurotoxicity is age-dependent, and younger pigs convulse at a higher LD(conv).

Posthypoxic hypothermia in newborn piglets

The purpose of this study was to determine whether mild hypothermia after a moderate hypoxic-ischemic insult reduces the extent of brain damage. Hypoxia was achieved in newborn piglets (n = 24; age, 14-72 h) by abrupt reduction of the inspired oxygen concentration (FiO2) to the maximum concentration (approximately 6%) giving low amplitude (< 7.0 microV) EEG. FiO2 was temporarily increased if heart rate, blood pressure, or end expiratory partial pressure of alveolar CO2 (PAco2) were markedly reduced. This intermittently resulted in EEG amplitude greater than 7 microV, the EEG traces were therefore later examined to determine the duration of low amplitude EEG. After 45 min of hypoxia, the animals were randomized to normothermia (39 degrees C) or hypothermia (35 degrees C) for 3 h. Hypothermia was achieved by applying packs containing ice water. Neurologic assessments and EEG recordings were performed regularly until 3 d when the brains were perfusion fixed. Histologic damage in cortex/white matter, cerebellum, hippocampus, basal ganglia, and thalamus was graded by a pathologist blind to treatment allocation. We found that the severity of brain damage (by histopathologic and neurologic evaluation) was not significantly different when the piglets were normothermic after hypoxia compared with the group made hypothermic. Increased duration of low amplitude EEG and seizure activity were associated with increased damage. When controlling for duration of hypoxia and excluding seizures, piglets undergoing hypothermia had approximately 50% less severe histopathologic damage in cortex/white matter, cerebellum, and hippocampus than those kept normothermic. Thalamus and basal ganglia had no or minor damage. It was concluded that there was no general beneficial effect of postinsult hypothermia. However, when controlling for the duration of the insult and occurrence of seizures, hypothermia reduced the severity of brain damage. This indicates a significant neuroprotective effect of 3 h of mild hypothermia on moderate, but not severe, hypoxic-ischemic insults.

A piglet survival model of posthypoxic encephalopathy

The aim of this study was to produce a neonatal piglet model which, avoiding vessel ligation, exposed the whole animal to hypoxia and produced dose-dependent clinical encephalopathy and neuropathologic damage similar to that seen after birth asphyxia. Twenty-three piglets were halothane-anesthetized. Hypoxia was induced in 19 piglets by reducing the fractional concentration of inspired oxygen (FiO2) to the maximum concentration at which the EEG amplitude was below 7 microV (low amplitude) for 17-55 min. There were transient increases in Fio2 to correct bradycardia and hypotension. Posthypoxia, the piglets were extubated when breathing was stable. Four were sham-treated controls. We aimed at 72-h survival; seven died prematurely due to posthypoxic complications. EEG and a videotaped itemized neurologic assessment were recorded regularly. We found that 95% of the animals showed neuropathologic damage. The duration of low amplitude EEG during the insult and the arterial pH at the end of the insult correlated with cortical/white matter damage; r = 0.75 and 0.81, respectively. Early postinsult EEG background amplitude (r = 0.86 at 3 h) and neurologic score (r = 0.79 at 8 h) correlated with neuropathology. Epileptic seizures in seven animals were always associated with severe neuropathologic damage. We conclude that EEG-controlled hypoxia and subsequent intensive care enabled the animals to survive with an encephalopathy which correlated with the cerebral hypoxic insult. The encephalopathy was clinically, electrophysiologically, and neuropathologically similar to that in the asphyxiated term infant. This model is suitable for examining mechanisms of damage and evaluation of potential protective therapies after birth asphyxia.

MAC for halothane and isoflurane during normothermia and hypothermia in the newborn piglet

BACKGROUND

Halothane and isoflurane are frequently used in studies of perinatal hypoxia and ischemia. Little information exists on the minimum alveolar concentration (MAC) necessary to prevent movement to a painful stimulus in newborn pigs and no information on the effects of hypothermia on MAC in pigs. Hypothermia is currently investigated as a posthypoxic neuroprotective intervention.

METHODS

The MAC of halothane and isoflurane necessary to prevent movement when a 25 cm hemostatic clamp was applied to the tail were determined in six 20-48-hour-old piglets, and when the same stimulus was applied to the hoof. MAC for halothane was first determined at 39 degrees C, then at 35 degrees C, whereafter halothane was discontinued and MAC for isoflurane determined first at 35 degrees C and then at 39 degrees C.

RESULTS

In all six piglets MAC was lower at 35 degrees C than at 39 degrees C for both anesthetics with both tail and hoof determination, lower for halothane than isoflurane for both stimuli at both temperatures, and lower for tail than hoof determination for both anesthetics at both temperatures. For halothane at 39 degrees C, mean (SD) MAC hoof was 0.82 (0.05)% vs tail 0.60 (0.12)%, and at 35 degrees C, hoof 0.65 (0.06)% vs tail 0.42 (0.10)%. For isoflurane at 39 degrees C, MAC hoof was 2.47 (0.28)% vs tail 1.83 (0.28)%, and at 35 degrees C, hoof was 1.83 (0.18)% vs tail 0.85 (0.25)%.

CONCLUSION

In the newborn piglet, MAC should be determined by hoof clamp, MAC of isoflurane is approximately three times that of halothane, and both are reduced during hypothermia.

Cerebral, tympanic and colonic thermometry in the piglet

The temperature of the brain is crucial for the outcome of hypoxic/ischaemic brain damage. In clinical medicine and in animal experiments involving survival after hypoxia/ischaemia, non-invasive measurement of cerebral temperature is needed. We have therefore compared tympanic and colonic temperature with cerebral temperature in the newborn piglet during hypothermia. Ten piglets aged 12-60 h were cooled to 35 degrees C (mild hypothermia) for 150 min and rewarmed. Thereafter, four of the piglets were again cooled to approximately 29 degrees C for less than one hour (moderate hypothermia). During stable mild hypothermia and normothermia the cerebro-tympanic temperature difference in individual piglets was less than +/- 0.4 degrees C (95% confidence intervals < or = 0.18 degrees C) and the cerebro-colonic temperature difference was -0.7 to 0.4 (95% confidence interval < or = 0.28 degrees C). The differences were larger during moderate than during mild hypothermia and largest during rapid changes in body temperature. Then the tympanic temperature correlated with the cerebral temperature significantly better than did the colonic temperature (95% confidence interval -0.3 to 0.3 versus -0.6 to 1.4 for the ten minutes with the least good correlation).

Haemoglobin is inversely related to plasma lactate and heart rate in the newborn piglet

It has been hypothesized that an increased level of plasma lactate (La), the product of anaerobic glycolysis, may identify infants with anaemia and early tissue hypoxia. In the newborn piglet, a frequently used model in experimental neonatology, there is a substantial decrease in haemoglobin (Hb) during the first days of life. We have investigated whether a low level of Hb is associated with an increased level of La in the newborn piglet. Arterial blood gas, Hb, glucose, La, and continuous blood pressure and heart rate (HR) recordings were obtained from 66 newborn piglets. In 4 additional piglets recordings were obtained before isovolemic anaemia, during isovolemic anaemia, and after retransfusion of packed red cells. A low concentration of Hb in the newborn piglet correlates with an increased level of La as well as with an increased HR. A reduction of Hb causes an increase in La and in HR. We hypothesize that increased La and increased HR are caused by mild hypoxia due to normal, low Hb levels in the apparently healthy, resting newborn piglet.

Postnatal development of the cerebral blood flow velocity response to changes in CO2 and mean arterial blood pressure in the piglet

Cerebral blood flow velocity was studied during changes (haemorrhage) in mean arterial blood pressure or P(a)CO2 in 56 (aged 0-26 days) anaesthetized and ventilated piglets. The CO2 reactivity increased with age from 6.5% kPa-1 (< 1 day) to adult levels of 25% kPa-1 for piglets over 4 days old. The mean arterial blood pressure reactivity was reduced from 1.3% mmHg-1 (< 1 day old) to 0.0%/mmHg (> 4 days old). The reactivities were similar with two different anesthetics: chloralose/urethane or pentobarbital. To validate the cerebral blood flow velocity data, both electromagnetic flow and precerebral Doppler ultrasound velocity were recorded from the same common carotid artery with extracranial branches tied off. There were no differences between the results with these two methods nor between these results and those obtained when the cerebral blood flow velocities were recorded from an intracerebral artery and the electromagnetic flowmeter recorded from the carotid artery. The vessel diameter appears stable during these interventions. In conclusion, the autoregulatory response and the reaction to P(a)CO2 appear poorly developed in the newborn piglet, but rapidly mature during the first 4 days of life.

The piglet as a model for cerebral circulation: an angiographic study

The aim of this study was to further investigate the possibilities and limitations of the newborn piglet as a model for neonatal cerebral circulation and injury. The precerebral and cerebral circulation was visualized by aortic arch contrast injection and selective injections into internal carotid and vertebral arteries. Due to the well-developed collateral circulation, it is not possible to produce severe focal cerebral ischemia in the piglet by ligation of extracranial arteries. It is possible to produce a modified common carotid artery which supplies mainly intracerebral tissues and is accessible for continuous measurements of cerebral blood flow.

Simultaneous measurements of cerebral circulation with electromagnetic flowmetry and Doppler ultrasound velocity in the newborn pig

Cerebral blood flow measurement has been an important investigative tool in newborns at risk for perinatal brain damage. The validity of Doppler cerebral blood flow velocity measurements depends on a constant vessel diameter. We have validated Doppler against the electromagnetic flowmeter (EM) using a modified common carotid artery model in the 1-d-old piglet. Two sets of continuous and simultaneous recordings were performed: 1) the Doppler and EM probe on the same common carotid artery (extracerebral branches were ligated), and 2) the EM probe on the common carotid artery and the Doppler probe recording from an intracerebral artery through an artificial fontanel. Arterial partial pressure of carbon dioxide (PaCO2) was manipulated (2.8-7.4 kPa), as was arterial blood pressure (3.7-9.3 kPa). Simultaneous EM flow and estimated Doppler flow were compared. Ninety-three recordings were obtained with both transducers on the modified carotid artery, and 49 were obtained with the Doppler insonicating an intracerebral artery. A multiple regression model was used for statistical analysis. The correlation between EM and both sets of Doppler measurements for individual animals was > 0.95 and was unaffected by changes in arterial blood pressure or PaCO2. Thus, the common carotid and the intracerebral artery investigated did not change their diameter significantly in response to PaCO2 or arterial blood pressure. The relationships between EM and Doppler in the individual animal were all linear but revealed great variability in the slopes due to the unknown vessel diameter and angle of insonication.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Doppler and misrepresentation of flow changes

To determine whether cerebral blood flow velocity (CBFV) measurements were representative of cerebral blood flow (CBF) changes in pathological flow situations five newborn piglets were investigated. They underwent measurements of CBF by electromagnetic flowmetry on a modified common carotid artery where extracerbral branches were tied off simultaneously with Doppler recording either from the same precerebral or an intracerebral artery. The two methods agreed well within moderate carbon dioxide and blood pressure changes. During severe hypotension and hypertension Doppler overestimated CBF by 25-100%. During transfusion of infected or incompatible blood the two methods differed in opposite directions with Doppler reading from 30-200% of CBF. Transfusion of chilled blood caused CBFV to overestimate 15% and heated blood caused 20% underestimation. These results could be explained by diameter changes in response to variation in myogenic tone or vasoactive substances. CBFV measurements could be seriously misleading in severe clinical derangements where neonatal brain damage might occur.

Dietary omega-3 fatty acid supplementation and naproxen treatment in patients with rheumatoid arthritis

In a controlled, double blind, clinical trial we tested the effect of dietary omega-3 fatty acid supplementation with and without naproxen and placebo, respectively, in 67 patients with active rheumatoid arthritis. The patients were randomized into 3 groups that received the following treatment: Group 1, corn oil ("placebo omega-3 fatty acids"), 7 g/day for 16 weeks, and naproxen, 750 mg/day for 10 weeks followed by a stepwise reduction to 0 mg/day during the following 3 weeks; Group 2, omega-3 fatty acids, 3.8 g of eicosapentaenoic acid plus 2.0 g of docosahexaenoic acid, and naproxen, 750 mg/day for 16 weeks; and Group 3, omega-3 fatty acids as Group 2 and naproxen as Group 1. At the end of the trial, patients in Group 2 had improved with respect to duration of morning stiffness and global assessment by physician and patient. In Groups 1 and 3 there was a significant deterioration for most of the variables measured. However, for duration of morning stiffness the deterioration was significantly less pronounced in Group 3 compared with Group 1. These effects might be ascribed to the dietary omega-3 fatty acid supplementation.

[Crib death, sleeping position and temperature]

Sudden infant death syndrome (SIDS) is the commonest cause of death in children over one week of age. Norway has the highest incidence in Scandinavia and the figure has increased during the last 20 years. There has been much discussion as to whether sleeping in the prone position rather than in the supine or lateral position may be a predisposing factor to cot death. In all 14 studies in seven countries where the question has been investigated, there was a higher proportion of prone infants in the SIDS group than in the control group. Intervention studies have shown that reducing the proportion of infants sleeping prone was followed by a reduction in cot deaths. There is also evidence that overheating is a risk factor for SIDS. In one British study it was found that infants who died of SIDS had more clothes on, and blankets covering them, and that both prone position and overheating were independently associated with SIDS. A possible mechanism is that overheating interferes with respiratory control. Although we do not completely understand the mechanisms underlying the links between SIDS and the prone position, the epidemiological evidence and the evidence from intervention are now so strong that it is fully justified to advice against the general use of the prone sleeping position for babies.

Hypocapnia and cerebral ischaemia in hypotensive newborn piglets

This study tested the hypothesis that hypocapnia superimposed upon hypotension produces a further reduction in cerebral blood flow velocity (CBFV). In 12 newborn piglets, CBFV was measured continuously by Doppler ultrasound through an artificial fontanelle. Hypotension was induced by removing 30 ml/kg of blood. Increasing the ventilator rate reduced the average arterial carbon dioxide tension from 5.5 to 2.0 kPa. When mean arterial pressure (MAP) was held steady at 45 mm Hg or above, hypocapnia produced a substantial drop in CBFV but, in all the piglets with MAP below 38 mm Hg, hypocapnia failed to change CBFV by 10%. Hypocapnia produced an increase in lactate in sagittal sinus blood but cerebral venous hypoxanthine concentrations were not affected by hypocapnia. Hyperventilation (without haemorrhage) produced a significant drop in MAP, preventable by infusing colloid. Hypocapnia itself does not further reduce CBFV in the hypotensive piglet. However, the pressure effect of hyperventilation may significantly impair the cerebral circulation.

Atlanto-axial subluxation in rheumatoid arthritis. A study of 104 hospital patients

Arthritic affection of the upper cervical spine is relatively common in rheumatoid arthritis (RA). Atlanto-axial subluxations are also reported to occur frequently, but it seems that neurological symptoms due to the subluxations seldom occur. We have studied 104 consecutive in-patients. In a group of 50 non-arthritics we have measured the distance from dens to the anterior arch of the atlas, and from dens to the foramen magnum line. By means of percentile-estimate we have defined values at risk for having pathological values for the measured distances. In 104 rheumatoid arthritis patients we found that 45% of the patients had values at risk, but only one of the patients had medullary neurological signs. A planned follow-up study will show if oncoming neurological symptoms due to subluxations will occur in the risk-group or in the group now defined as having normal values.