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Biomedical subjects

A Ohlsson

Publications and source records attributed to A Ohlsson.

At least 109 records · Page 6Linked to original sources
PubMed1996

Randomized controlled trials and systematic reviews: a foundation for evidence-based perinatal medicine.

The objective of this paper is to introduce the reader to clinical research methodologies and to illustrate how randomized controlled trials (RCTs) and systematic reviews provide a solid foundation for evidence-based perinatal practice. Relevant references were critically appraised for validity and usefulness. Random allocation is of utmost importance to avoid bias. There are thousands of reported perinatal RCTs. Systematic review techniques allow clinicians to assess the effectiveness of perinatal interventions. The application of the results of systematic reviews to perinatal practice is increasing. RCTs and systematic reviews provide the most valid results on which to build an evidence-based perinatal practice. A major challenge for perinatal researchers is the development of innovative means of communication. This assures that the evidence for an effective intervention is timely implemented. Consumers of care should be encouraged to actively participate in the design, execution and dissemination of perinatal research.

Bias↗
PubMed1996

Enterostatin efflux in cat intestinal lymph: relation to lymph flow, hyaluronan, and fat absorption.

The question addressed in this study was whether enterostatin, the pancreatic procolipase activation peptide, modulates intestinal hyaluronan turnover via lymph. In anesthetized cats, segments of ileum were surgically isolated from the proximal and distal gut, the draining lymphatic was cannulated, and the segment was autoperfused in situ. In several groups, concentrations of immunoreactive enterostatin in lymph were compared with that in plasma at baseline and elevated lymph flow and in the absence and presence of fat absorption. The baseline ratio of lymph enterostatin to that in plasma (L/P) in the absence of fat absorption was 1.44 +/- 0.29 compared with 4.93 +/- 0.42 after cream feeding (P < 0.05). In a separate group, when the intestinal lumen was perfused for 2 h with a mixture of oleic acid and taurocholate, enterostatin L/P doubled compared with baseline. At high lymph flows, enterostatin concentrations fell in all groups, resulting in an L/P of 0.47 +/- 0.09 (P < 0.05) in the absence of fat absorption, 0.77 +/- 0.35 after oleic acid, and 1.26 +/- 0.13 in the cream-fed group. These changes correlate with the pattern of hyaluronan efflux from the ileum into lymph after fat absorption [R.K. Reed, M.I Townsley, V.H. Pitts, T.C. Laurent, and A.E. Taylor. Am. J. Physiol, 263 (Gastrointest. Liver Physiol. 26): G6-G11, 1992] However, in separate groups when enterostatin was introduced into ileum, either as a close intra-arterial bolus or via the intestinal lumen, there were no resultant changes in efflux of hyaluronan from the intestine into lymph. In conclusion, despite the fact that delivery of pancreatic exocrine secretions to the ileal lumen was blocked in this model, enterostatin concentration in lymph increased after fat absorption. Nonetheless, it seems clear that enterostatin does not modify intestinal hyaluronan turnover.

Animals↗
PubMed1996

Measurement of methemoglobin after EMLA analgesia for newborn circumcision.

A statistically significant (p = 0.049) increase in methemoglobin (MetHb), which did not exceed normal values, was noted 8 h after application of 1 g of EMLA (Eutectic Mixture of Local Anesthetics) to the foreskin of 10 normal newborns to reduce pain associated with circumcision. The highest MetHb concentration observed was 3 g/l (toxic > 50 g/l). No infant showed clinical signs of methemoglobinemia. We conclude that EMLA is safe to use as a local anesthetic in term neonates.

Analgesia↗
PubMed1996

Doppler velocimetry of the fetal middle cerebral and renal arteries: interobserver reliability.

Using color and pulsed Doppler ultrasonography, the interobserver reliability of measurements in the fetal circulation was evaluated in 41 pregnancies of 25 to 39 weeks' gestation. Two observers recorded flow velocity waveforms from the middle cerebral and renal arteries for measurement of peak systolic, minimum diastolic, and mean velocities, pulsatility index, and resistive index. Intraclass correlation coefficient of reliability was calculated by analysis of variance. Substantial interobserver agreement was found for pulsatility index and minimum diastolic velocity in both arteries. Therefore, these measurements have the greatest clinical applicability.

Adult↗
PubMed1995

Superior mesenteric artery and renal artery blood flow velocity measurements in neonates: technique and interobserver reliability.

The objective of this study was to establish the interobserver reliability for superior mesenteric artery (SMA) and renal artery (RA) Doppler blood flow velocity (BFV) measurements in neonates. Forty-two clinically stable infants were enrolled, mean (SD) gestational age 33 (2) weeks, birthweight 2.00 (0.54) kg, postnatal age 10 (11) days. Doppler recordings were made by two trained observers. The SMA and RA were studied with a 5.0-MHz phased array transducer. The optimal spectral trace from each artery containing a minimum of five consecutive waveforms was analysed. The peak systolic velocity (PS), end diastolic velocity (ED) and mean peak velocity (MV) were measured and the time-averaged mean velocity (TAV) and waveform indices were calculated. Using the intraclass correlation coefficient (ICC) the estimates of interobserver reliability for different measurements varied from 0.40 to 0.83. Substantial agreement was obtained between observers in the TAV, PS, ED and MV; the ICC varied from 0.72 to 0.83 demonstrating that Doppler BFV measurements of the SMA and RA are reliable in neonates.

Blood Flow Velocity↗
PubMed1995

Meta-analysis of enteral nutrition as a primary treatment of active Crohn's disease.

BACKGROUND/AIMS: The efficacy of enteral nutrition as primary therapy of active Crohn's disease is controversial. The aim of the study was to compare by meta-analysis the likelihood of clinical response to liquid diet therapy vs. corticosteroids and to assess the importance of formula composition to efficacy. METHODS: Randomized controlled trials comparing exclusive enteral nutrition with corticosteroids and elemental with nonelemental formulas were identified through a combination of computerized and hand-searching techniques. Rates of clinical remission of active Crohn's disease, based on the intention-to-treat principle, were extracted from the studies by two independent reviewers. Odds ratios for likelihood of clinical response were calculated. RESULTS: In eight trials comprising 413 patients, enteral nutrition was inferior to corticosteroids (pooled odds ratio, 0.35; 95% confidence interval, 0.23-0.53). In five trials comprising 134 patients, there was no difference in the efficacy of elemental versus nonelemental formulas (pooled odds ratio, 0.87; 95% confidence interval, 0.41-1.83). CONCLUSIONS: Corticosteroids are more effective than enteral nutrition in the treatment of active Crohn's disease. Limited sample size precludes definitive conclusions about the importance of formula composition in the efficacy of enteral nutrition; however, data analyzed in this study do not support an advantage to elemental feedings compared with a polymeric formulation.

Adrenal Cortex Hormones↗
PubMed1995

Monitoring of pulmonary arterial diastolic pressure through a right ventricular pressure transducer.

Pulmonary arterial diastolic pressure is an important parameter for hemodynamic monitoring in congestive heart failure. It is traditionally obtained through a pulmonary arterial catheter. If it could be obtained from a sensor in the right ventricle, chronic monitoring would be possible without the use of a pulmonary arterial catheter. This study is based on the hypothesis that pulmonary valve opening and pulmonary arterial diastolic pressure occur at the time of maximum positive rate of pressure development (dP/dt) in the right ventricle, when the pressures should be equal. Thus, right ventricular pressure at the time of maximum dP/dt (PAD index) should be a reasonable estimate of pulmonary arterial diastolic pressure. Eight patients with heart failure were catheterized and exposed to hemodynamic stress. Right ventricular and pulmonary arterial pressures were simultaneously recorded from a Millar (Houston, TX) catheter with two pressure transducers. The distal transducer was positioned in the bifurcation of the pulmonary artery and the proximal transducer was placed in the right ventricle. Pulmonary arterial diastolic pressure and PAD index were stored beat by beat on a bed-side computer. Acceptable recordings were obtained in all patients. Recordings from the individual patients showed a good covariation between PAD index and pulmonary arterial pressure during different hemodynamic manuevers, except during infusion of dobutamine, when the correlation was not as good. Pulmonary arterial diastolic pressure may be estimated from a transducer in the right ventricle, thus eliminating the need for a permanent pulmonary arterial catheter in an implantable hemodynamic monitoring system. Further studies are needed to verify the correlation on a long-term basis.

Aged↗
PubMed1995

Association of Ureaplasma urealyticum colonization with chronic lung disease of prematurity: results of a metaanalysis.

OBJECTIVES: We performed a metaanalysis to determine whether there is an association between Ureaplasma urealyticum and chronic lung disease of prematurity (CLD); most studies involved small sample sizes, and the reported lack of statistical significance could have been due to inadequate power. METHODS: Articles were identified from the literature through a search of MEDLINE, Excerpta Medica, and Reference Update, with the search terms "Ureaplasma urealyticum," "CLD," and "bronchopulmonary dysplasia." The search was initially conducted in June 1994 and updated in March 1995. Abstracts were identified through a hand search of proceedings from two meetings for the years 1987 through 1994. Summary data on frequency of CLD in U. urealyticum-colonized and uncolonized babies were independently determined by the three authors. Preterm and term neonates were included. Colonization required recovery of U. urealyticum from a respiratory or surface specimen. The presence of CLD at 28 or 30 days was determined. RESULTS: Seventeen publications comprising 13 full publications and 4 abstracts were included in the analysis. The estimates for relative risk (RR) exceeded one in all studies, although the lower confidence interval included one in seven studies. The RR for the development of CLD in colonized neonates was 1.72 (95% confidence interval, 1.5 to 1.96) times that for uncolonized neonates. The RR was not significantly different for abstracts versus full publications; studies focusing on extremely premature, low birth weight neonates versus studies including all neonates; and studies in which only endotracheal aspirates were used to define colonization versus others. The RR since surfactant use was somewhat lower than in studies in which receipt of surfactant was unknown. CONCLUSIONS: This metaanalysis supports a significant association between U. urealyticum colonization and subsequent development of CLD. A randomized, controlled trial showing a reduction in CLD through the use of an antibiotic effective against U. urealyticum would provide further support of a causative role for this agent.

Chronic Disease↗
PubMed1995

Monitoring of mixed venous oxygen saturation and pressure from biosensors in the right ventricle. A 24 hour study in patients with heart failure.

Right ventricle venous oxygen saturation was studied in 10 heart failure patients over 24 h using a lead equipped with an oxygen biosensor inserted temporarily. At the same time a pressure sensor, incorporated in the same lead to measure right ventricular pulse pressure and maximum positive and negative rate of pressure development (RV dP/dt), was tested to see whether it would interfere with the oxygen sensor. Data from the biosensor lead were continuously compared with mixed venous oxygen saturation obtained from a fibreoptic Swan-Ganz catheter with the tip in the pulmonary artery. For reference, blood samples were drawn at regular intervals from this catheter. A provocative protocol was used to cause haemodynamic changes. There was good correlation between oxygen saturation in the right ventricle (biosensor-derived) and mixed venous oxygen saturation in the pulmonary artery (fibreoptic-derived) (r = 0.86) and between sensor-obtained right ventricular oxygen saturation and oxygen saturation in the blood samples from the pulmonary artery (r = 0.90). Changes in central haemodynamics were also well reflected by changes in pulse pressure and dP/dt derived from the pressure sensor. As it was not possible to obtain absolute pressures no attempt was made to compare the pressure changes with conventional haemodynamics. These 24 h haemodynamic measurements suggest that a biosensor-equipped lead placed in the right ventricle could be a valuable tool for long-term monitoring of mixed venous oxygen saturation and pressure in patients with congestive heart failure.

Aged↗
PubMed1995

Accuracy of leukocyte indices and C-reactive protein for diagnosis of neonatal sepsis: a critical review.

To evaluate the value of C-reactive protein and leukocyte indices in the workup of patients suspected of having infection in a neonatal intensive care setting, a literature search was conducted in all languages using MEDLINE (1966 to May, 1994), EMBASE (1988 to May, 1994), bibliographic lists of primary and review articles and personal files. Citations identified as potentially relevant were reviewed by two independent investigators; only studies meeting preset criteria for population, diagnostic test and data presentation were included. Two observers independently assessed studies using explicit methodologic criteria. All data from the articles were extracted by one observer, whereas the second reviewer checked these data for accuracy. Four of the selected studies dealt with leukocyte count and ratios. The chi square test for homogeneity of proportions revealed significant heterogeneity across studies (P = 0.014 for the ratios; P < 0.001 for white blood cell count), suggesting that test properties varied widely across studies. Fifteen of the selected studies evaluated C-reactive protein; of these six were qualitative using a latex agglutination method. Among these studies the chi square test for homogeneity of proportions was highly significant (P < 0.01), reflecting the great heterogeneity across studies. Among the nine studies that evaluated five different quantitative methods heterogeneity was again present (P < 0.001). Because of the striking heterogeneity among the studies evaluated, pooling to give a summary point estimate of the sensitivity and specificity of the various studies was not possible and the results are reported as ranges.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers↗
PubMed1995

Aminophylline and Doppler time-averaged mean velocity in the middle cerebral artery in preterm neonates.

OBJECTIVE: The purpose of this study was to assess the effect of an intravenous loading dose of aminophylline (6 mg/kg) on Doppler time-averaged mean velocity in the middle cerebral artery in ventilated preterm neonates. METHODOLOGY: Twenty infants were studied by colour/duplex Doppler technique prior to and at 5, 10, 30 and 60 min after the administration of aminophylline. RESULTS: Aminophylline treatment was associated with a statistically significant reduction in time-averaged mean velocity from baseline (P < 0.001) and an increase in heart rate (P < 0.001) at all timepoints. The largest reduction in time-averaged mean velocity of 19% (95% confidence interval -10 to -28%) occurred at 10 min post-dose. There were no statistically significant changes in transcutaneous PCO2 or mean arterial blood pressure. CONCLUSIONS: The observed reduction of 19% from baseline in time-averaged mean velocity following treatment with aminophylline alone is unlikely to be of clinical importance. Whether aminophylline in combination with other drugs that decrease central blood flow velocity such as indomethacin and/or dexamethasone could result in a clinically significant reduction deserves further study.

Aminophylline↗
PubMed1995

Administration of intravenous immunoglobulins for prophylaxis or treatment of infection in preterm infants: meta-analyses.

AIMS: To determine the effectiveness of intravenous immunoglobulin administration to premature infants in the prevention and/or treatment of bacterial infection. METHODS: Computer searches of MEDLINE, EMBASE, SCISEARCH and Oxford Database of Perinatal Trials were made. Two independent researchers applied inclusion criteria of: randomised controlled trial; premature and/or low birthweight infant; use of intravenous immunoglobulin; and infection or mortality. Nineteen of 44 identified studies fulfilled these criteria. Study quality was assessed and information on study population, intervention, and outcomes were collected. RESULTS: Studies were divided into prophylaxis or treatment; results were tabulated for infection, sepsis, and death from all causes. For 17 studies of prophylaxis (n = 5245), the relative risk and confidence interval were, for proved infection 0.81, 0.67-0.97; for sepsis 0.87, 0.66-1.13; for death from all causes 0.85, 0.64-1.14. Some outcome results were heterogeneous. Two treatment studies showed no reduction in mortality when combined. CONCLUSIONS: Routine administration of intravenous immunoglobulin to preterm infants is not recommended.

Bacterial Infections↗
PubMed1994

The effect of dexamethasone on time averaged mean velocity in the middle cerebral artery in very low birth weight infants.

The effect of repeated doses of dexamethasone (0.25 mg/kg/dose every 12 h) on time averaged mean velocity in the middle cerebral artery was assessed in ten ventilated very low birth weight infants requiring treatment with dexamethasone for bronchopulmonary dysplasia or airway obstruction. The infants were studied by colour/duplex Doppler technique prior to the administration of the first and the third dose of dexamethasone, and 10, 30, and 120 min after these doses. Dexamethasone treatment was associated with an improvement in infant lung condition, an increase in mean arterial blood pressure and a decrease in heart rate. The time averaged mean velocity was statistically significantly reduced at 120 min after the first dose. This was not associated with a decrease in PCO2. The observed reduction of 18% from baseline in the time averaged mean velocity is unlikely to be of clinical importance.

Airway Obstruction↗
PubMed1994

Uterine and umbilical blood flow velocity during epidural anaesthesia for caesarean section.

The purpose of this study was to use colour Doppler to determine the effect of epidural anaesthesia on the uterine and umbilical blood flow velocities. After determining the precision of the technique, Doppler insonation of the uterine and umbilical arteries was performed in consenting non-labouring patients requesting epidural anaesthesia for Caesarean section. Patients in Group I were normal and those in Group II were at high risk for uteroplacental blood flow abnormalities. The pulsatility indexes (PI) of both uterine and umbilical arteries were compared at the following times: control, after fluid and after anaesthesia using repeated measure analysis of variance. In Group I (n = 30) the PI increased from 0.72 to 0.82 in the left uterine artery and from 0.71 to 0.85 in the right uterine artery (P < 0.05). In Group II (n = 10) the PI increased from 0.67 to 0.85 in the left uterine artery (NS) and from 0.98 to 1.38 in the right uterine artery (P < 0.05). There was no change in the PI in the umbilical artery. We conclude that the PI of the uterine arteries increases after epidural anaesthesia with lidocaine, epinephrine and fentanyl but there is no change in the umbilical PI. While these changes do not appear to be clinically important in the low-risk population, further studies are required to determine the impact on fetuses at high risk for in utero hypoxaemia.

Adult↗