Systematic review of transpyloric versus gastric tube feeding for preterm infants

AIM

To determine if enteral tube feeding by the transpyloric versus the gastric route improves feeding tolerance, and growth and development, without increasing adverse events, in preterm infants.

METHODS

Systematic review of randomised controlled trials. A search was made of the Cochrane Controlled Trials Register (CCTR; 2003, issue 1), Medline (1966 to April 2003), and Embase (1980 to April 2003), and references in previous reviews. The data were extracted, analysed, and synthesised using the standard methods of the Cochrane Neonatal Collaborative Review Group.

RESULTS

Data were found from eight trials. No evidence of an effect on growth or development was found, but transpyloric feeding was associated with a greater incidence of gastrointestinal disturbance: relative risk (RR) 1.45, 95% confidence interval (CI) 1.05 to 2.09. Transpyloric feeding was also associated with increased mortality: RR 2.46, 95% CI 1.36 to 4.46. However, the trial that contributed most to this finding may have been affected by allocation bias. No significant differences were detected in the incidence of other adverse events, including necrotising enterocolitis, intestinal perforation, and aspiration pneumonia.

CONCLUSIONS

No evidence of benefit was found, but evidence of harm was found. Feeding by the transpyloric route cannot be recommended for preterm infants.

Evaluating the performance of the Framingham risk equations in a population with diabetes

AIMS

The Framingham risk equations are widely used to estimate risk of coronary heart disease (CHD). The purpose of this study was to evaluate the reliability of these equations in predicting CHD risk in people with diabetes and the reliability of using imputed mean HDL-cholesterol values.

METHODS

Data describing the baseline characteristics of recognized CHD risk factors for 938 people aged 30-74 years were extracted from the Cardiff Diabetes Database. Data describing CHD events were available for up to 4 years following the baseline year (1996). Several mathematical techniques were used to assess the reliability of predictions provided by the Framingham equations in this population.

RESULTS

Thirty-four percent of males and 25% of females who experienced CHD events had a predicted 10-year CHD risk >/= 30%. Seventy-five percent of males and 58% of females had a predicted 10-year CHD risk >/= 20%. Using imputed HDL-cholesterol values, 26% of males and 6% of females who later developed CHD events had a 10-year CHD risk >/= 30%. Using imputed HDL-cholesterol values, the CHD risk predicted by the Framingham equations consistently underestimated the actual risk of CHD events. However, refitting the Framingham risk equations to the Cardiff data resulted in only marginal improvements in discriminatory capabilities.

CONCLUSIONS

The Framingham risk equations can be unreliable when applied to the diabetic population, tending to underestimate an individual's probability of progressing to CHD; the equations perform marginally better in women than in men. The use of imputed mean HDL-cholesterol values improved the reliability of the estimates of risk.

Evaluation of the future supply and demand for blood products in the United Kingdom National Health Service

In addition to the clinical management of blood supplies, the UK National Blood Service (NBS) examines short-term supply and demand to predict any potential shortages in blood supplies. However, very little data are available on the medium- and long-term trends. This paper describes blood product use in a United Kingdom Hospital Trust in 1999 and combines it with donor information to project the effect of demographic changes on demand and supply over the next 25 years. Overall, 2801 (4%) inpatients received transfusions of blood products. The proportion of inpatients receiving blood products increased with age. Patients aged >70 years used 46% of the total blood product supply, whereas patients aged <30 years used 10%. The estimated total cost associated with blood product use was pound 2 million during 1999 (2001-2002 prices). The results show that within 20 years, demand for blood products is expected to increase by 20% relative to the supply. The estimates in this study are a valuable aid to better long-term planning of supplies. As there is a paucity of data concerning blood product use in UK hospitals and blood use varies greatly between hospitals, further studies are required to guide blood product use policy.

Nasal versus oral route for placing feeding tubes in preterm or low birth weight infants

BACKGROUND

Enteral feeding tubes for preterm or low birth weight infants may be placed via either the nose or mouth. Nasal placement may compromise respiration. However, orally placed tubes may be more prone to displacement, local irritation, and vagal stimulation.

OBJECTIVES

To assess the available evidence from randomised controlled trials concerning the effects of nasally placed compared with orally placed feeding tubes on growth and development, and the incidence of adverse consequences in preterm or low birth weight infants.

SEARCH STRATEGY

We used the standard search strategy of the Cochrane Neonatal Review Group, including electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2004), MEDLINE (1966 - April 2004), EMBASE (1988 - April 2004), and CINAHL (1982- April 2004), conference proceedings, and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared the use of the nasal versus oral route for placing feeding tubes in preterm or low birth weight infants.

DATA COLLECTION AND ANALYSIS

We extracted data using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by each author, and analysis of data using relative risk, risk difference and mean difference.

MAIN RESULTS

We found only one eligible trial. Forty-two infants participated in the study. This primary aim of the trial was to assess the effect of oral versus nasal placement of feeding tubes on the incidence of apnea and periodic breathing in preterm infants. The trial did not report data on the pre-specified primary outcomes for this review (growth and development).

REVIEWERS' CONCLUSIONS

There are insufficient data available to inform practice. A large randomised controlled trial is required to determine if the use of nasally placed feeding tubes compared with orally placed feeding tubes improves growth and development, without increasing adverse consequences in preterm or low birth weight infants.

The genome of M. acetivorans reveals extensive metabolic and physiological diversity

Methanogenesis, the biological production of methane, plays a pivotal role in the global carbon cycle and contributes significantly to global warming. The majority of methane in nature is derived from acetate. Here we report the complete genome sequence of an acetate-utilizing methanogen, Methanosarcina acetivorans C2A. Methanosarcineae are the most metabolically diverse methanogens, thrive in a broad range of environments, and are unique among the Archaea in forming complex multicellular structures. This diversity is reflected in the genome of M. acetivorans. At 5,751,492 base pairs it is by far the largest known archaeal genome. The 4524 open reading frames code for a strikingly wide and unanticipated variety of metabolic and cellular capabilities. The presence of novel methyltransferases indicates the likelihood of undiscovered natural energy sources for methanogenesis, whereas the presence of single-subunit carbon monoxide dehydrogenases raises the possibility of nonmethanogenic growth. Although motility has not been observed in any Methanosarcineae, a flagellin gene cluster and two complete chemotaxis gene clusters were identified. The availability of genetic methods, coupled with its physiological and metabolic diversity, makes M. acetivorans a powerful model organism for the study of archaeal biology. [Sequence, data, annotations and analyses are available at http://www-genome.wi.mit.edu/.]

Transpyloric versus gastric tube feeding for preterm infants

BACKGROUND

Enteral feeding tubes for preterm infants may be placed in the stomach (gastric tube feeding) or in the upper small bowel (transpyloric tube feeding). There are potential advantages and disadvantages to both routes.

OBJECTIVES

In preterm infants who require enteral tube feeding, does feeding via the transpyloric route versus the gastric route improve feeding tolerance, and growth and development, without increasing adverse consequences?

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group was used. This included electronic searches of MEDLINE and EMBASE (up to December 2001) and of The Cochrane Controlled Trials Register in The Cochrane Library (Issue 3, 2001), and searches of the references in previous reviews including cross references.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing transpyloric with gastric tube feeding in preterm infants.

DATA COLLECTION AND ANALYSIS

Data were extracted using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by each author and synthesis of data using relative risk and weighted mean difference.

MAIN RESULTS

Data from eight trials were available. We did not find any evidence of an effect on growth rates: short term weight gain, weighted mean difference -0.7 g/week (95% confidence interval -25.2, 23.8); short term increase in crown heel length, weighted mean difference -0.7 mm/week (95% confidence interval -2.4, 1.0); short term increase in head circumference, weighted mean difference 0.6 mm/wk (95% confidence interval -0.9, 2.1). Longer term growth was reported in one study. There were not any statistically significant differences between the groups in the mean body weight or occipitofrontal head circumference at three months or at six months corrected age. None of the included studies provided data on neurodevelopmental outcomes during infancy or beyond. Transpyloric feeding was associated with a greater incidence of gastro-intestinal disturbance, RR 1.45, 95% CI 1.05, 2.09. There was some evidence that feeding via the transpyloric route increased mortality, RR 2.46, 95% CI 1.36, 4.46; however, the outcomes of the study that contributed most to this finding were likely to have been affected by selective allocation of the less mature and sicker infants to transpyloric feeding. We did not detect any statistically significant differences in the incidence of other adverse events, including necrotising enterocolitis, intestinal perforation, and aspiration pneumonia.

REVIEWER'S CONCLUSIONS

We did not find any evidence of benefit, but did find evidence of adverse effects, of transpyloric feeding in preterm infants. Feeding via the transpyloric route cannot be recommended for preterm infants.

In vivo analysis of porcine endogenous retrovirus expression in transgenic pigs

Xenotransplantation offers a potential solution to the shortage of donor organs for allotransplantation. In vitro studies that demonstrate the transmission of porcine endogenous retroviruses (PERV) from porcine cells to human cells and cell lines have raised concerns regarding the potential transmission of PERV to both xenograft recipients and their contacts (1-4). While no evidence of infection has been detected in any patients who have been treated with a variety of different porcine tissues (5-8), two studies have shown that severe combined immunodeficient (SCID) mice can be infected by PERV after the transplantation of porcine islets (9-10). To further address the concerns of PERV, expression of this virus in tissues and serum from transgenic pigs that express human decay accelerating factor was investigated. Although viral mRNA expression was detected in a variety of tissues, no evidence of viral release was observed in any of the porcine tissues analyzed by transmission electron microscopy. Analysis of porcine serum using the product-based reverse transcriptase assay suggested that virions may be present in porcine serum from large white pigs. However, using methods based on those previously described by Wilson et al. (4), infectious virus was not detected when activated peripheral blood mononuclear cells from these pigs were cocultivated with human cells known to be permissive for PERV.

Short report: Hyperammonaemia in critically ill septic infants

Three infants with subphrenic abscess, pyonephrosis, and obstructive ureterocoele respectively had grossly increased concentrations of plasma ammonia. This was considered to be a result of infections with urea splitting organisms. All died in spite of intensive care support, including specific measures to reduce plasma ammonia.

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Eight hundred-base sequencing in a microfabricated electrophoretic device

The human genome will be sequenced using capillary array electrophoresis technology. Although currently achieving only 550 base reads per run, capillary arrays have increased the efficiency and lowered the cost of sequencing by eliminating gel plate preparation, reducing sample volumes, and offering automation and speed. However, much higher throughput and greater cost reductions are needed. The next major advancement in sequencing technology is expected from the development of arrays of microfabricated channels in a plate or "chip" format. For de novo sequencing, the practical utility of the microdevice approach has been limited by device length to a read of 500-600 bases per run. We demonstrate a significant milestone for a microfabricated device by obtaining an average read length of 800 bases in 80 min (98% accuracy) for either M13 standards or DNA sequencing samples from the Whitehead Institute Center for Genomic Research (WICGR) production line. This result is achieved in 40-cm-long channels using a new class of large-scale microfabricated devices. Both microfabrication of extended structures and achievement of long reads are essential steps toward a 384-lane very-large-scale microfluidic (VLSMF) system for ultrahigh-throughput DNA sequencing analysis, currently under construction in our laboratory.

Toward real-world sequencing by microdevice electrophoresis

We report results using a microdevice for DNA sequencing using samples from chromosome 17, obtained from the Whitehead Institute Center for Genome Research (WICGR) production line. The device had an effective separation distance of 11.5 cm and a lithographically defined injection width of 150 microm. The four-color raw data were processed, base-called by the sequencing software Trout, and compared to the corresponding ABI 377 sequence from WICGR. With a criteria of 99% accuracy, we achieved average continuous reads of 505 bases in 27 min with 3% linear polyacrylamide (LPA) at 150 V/cm, and 460 bases in 22 min with 4% LPA at 200 V/cm at a temperature of 45 degrees C. In the best case, up to 565 bases could be base-called with the same accuracy in <25 min. In some instances, Trout allowed for accurate base-calling down to a resolution R as low as R = 0.35. This may be due in part to the high signal-to-noise ratio of the microdevice. Unlike many results reported on capillary machines, no additional sample cleanup other than ethanol precipitation was required. In addition, DNA fragment biasing (i.e., discrimination against larger fragments) was reduced significantly through the unique sample injection mechanism of the microfabricated device. This led to increased signal strength for long fragments, which is of great importance for the high performance of the microdevice.

Ejection fraction by radionuclide ventriculography and contrast left ventriculogram. A tale of two techniques. SAVE Investigators. Survival and Ventricular Enlargement

OBJECTIVES

We assessed the abilities of two methods to measure ejection fraction (EF)-radionuclide ventriculography (RVG) and contrast left ventriculography (Cath-EFa) to predict cardiovascular events.

BACKGROUND

Both RVG and Cath-EFa are commonly used methods to measure left ventricular performance and assess prognosis. Their comparative abilities to predict clinical events have not been reported.

METHODS

Both RVG EF and Cath-EFa were measured within 16 days of myocardial infarction (MI) in 688 patients. The results were divided into terciles. Prognosis by terciles was assessed for each technique. A multivariate analysis was performed to determine which EF measurement was a better predictor of prognosis.

RESULTS

Average RVG-EF was 32%+/-7, while Cath-EFa was 42%+/-10. Both RVG and Cath-EFa were poorly correlated (R=0.42). Event rate declined across terciles with increasing EF for both techniques (events in lowest to highest tercile of Cath-EFa 40.7%, 25.9%, 11.6%, p < 0.001; and RVG-EF 39.9%, 26.1%, 15.6%, p < 0.001). There was concordance of terciles in 303 of 688 patients (44%). When patients in the highest RVG terciles were in the highest Cath-EFa tercile, the event rate was 7%. However, when patients in the highest RVG terciles were in the lowest Cath-EFa tercile, the event rate was 19%. Both Cath-EFa (p < 0.001) and RVG-EF (p < 0.001) were independent predictors of cardiovascular events.

CONCLUSIONS

Ejection fraction measured by RVG or during catheterization is a valuable tool in the risk stratification of postinfarct patients. When disagreement is present between clinical impression and measurement by either method, the use of an alternative measurement is warranted and complementary.

Sotalol-induced torsades de pointes in patients with renal failure

The risk of torsades de pointes in patients on sotalol is increased in the setting of renal failure. QT dispersion and prolonged QT intervals have been described as markers for pro-arrhythmia. Four cases of torsades de pointes caused by low dose sotalol in patients with renal failure are reported. All four cases demonstrated that the 12-lead electrocardiogram, with markedly prolonged QT intervals and increased QT dispersion, could have been used to predict pro-arrhythmia.

Proximal narrowing of anomalous right coronary artery from the left coronary sinus: delineation by omniplane transesophageal echocardiogram

Anomalous origin of the right coronary artery from the left sinus of Valsalva is a serious and potentially fatal, albeit rare, congenital abnormality. It can be associated with marked functional impairment and even sudden death. Transesophageal echocardiography can identify and confirm the course of aberrant coronary arteries and their relationship to the great vessels, as is demonstrated in this report of a 51-year-old female presenting with anomalous right coronary artery with narrowing of its proximal portion.

Vascular structure, smooth muscle cell phenotype and growth in hypertension

The media of most blood vessels is occupied by vascular smooth muscle cells. In areas they may be replaced by glomus cells, pericytes or renin-secreting myoepithelioid cells. These cells may be regarded as phenotypic variants of vascular smooth muscle cells. In disease, ordinary vascular smooth muscle cells may also assume a spectrum of phenotypes ranging from contractile to largely secretory types. Therefore, the phenotype of smooth muscle cells that is involved in a disease process such as hypertension or one of its complications is likely to affect the structural outcome in blood vessels.

Capsular contracture simulating myocardial infarction on ECG

A patient is presented with severe bilateral class IV capsular contractures who presented 16 years after prepectoral breast augmentation with a "septal infarct" pattern on ECG. This abnormal ECG proved to be an artifact caused by unavoidable misplacement of the V2 and V3 leads because of the severe capsular contracture. Following open capsulotomy, normal anatomic lead placement was possible, and a normal ECG was produced.

Dispersive flight by Triatoma sordida

One hundred and thirty-two male and female Triatoma sordida were marked with fluorescent paint and released at an experimental site on the salt flats of central Argentina, distant from any inhabited dwellings. Flight by these bugs commenced just after sunset, and the bugs were then systematically searched for using portable ultraviolet lights. There was no apparent tendency for the bugs to fly in any particular direction, but those whose flight could be observed directly all seemed to fly in approximately straight lines at a height of 0.5-1 m. Of the 86 bugs that flew from the release point, 16 made trivial flights of less than 5 m, 4 landed at distances of 60-90 m away, while the other bugs were not recovered and appear to have flown further than 100 m. As expected from similar studies with T. infestans, the proportion of bugs initiating flight declined with increasing weight-length ratio, but T. sordida showed a much higher propensity for flight under these conditions than did T. infestans.

Failure of bicycle exercise electrocardiograms to predict major post-operative cardiac complications in patients undergoing abdominal aortic surgery

To determine if exercise electrocardiograms (EECGs) are justified in routine pre-operative screening for cardiac disease, we performed a prospective study on 77 consecutive patients scheduled for infrarenal aortic reconstructive surgery. All patients had EECGs performed 1-12 days prior to elective surgery. In addition to routine clinical assessment of cardiac disease, all patients were allocated a Goldman risk score. Four patients developed major post-operative cardiac complications of whom one patient died. EECG was not a significant predictor of outcome, as 48.6% of all EECGs were inadequate due to non-completion of the exercise protocol. Significant pre-operative predictors of outcome were a history of angina (p less than 0.01), myocardial infarction (p less than 0.001), congestive cardiac failure (p less than 0.0001), or a Goldman score of greater than 14 (p less than 0.05). By multivariate analysis of the pre-operative risk factors a history of congestive cardiac failure was found to be the most significant independent predictor of post-operative cardiac complications.

Radionuclide angiography and endomyocardial biopsy in the assessment of doxorubicin cardiotoxicity

Thirty-eight patients with a mean age of 53.2 years (19 to 75 years of age), who were receiving doxorubicin (D) for malignant disease, were studied in order to determine the relationship between functional and morphologic myocardial changes at different dose levels. Serial patient evaluations included physical examination, chest x-ray, electrocardiogram (ECG), endomyocardial biopsy (EMB), and rest-exercise gated nuclear angiography (GNA), at doses of D ranging from 144 to 954 mg/m2 (mean, 426 mg/m2). Physical examination, chest x-ray, and ECG proved to be insensitive predictors of D cardiotoxicity. Correlation of GNA and EMB in 31 patient evaluations, exclusive of known heart disease, did not reveal any false-positive angiograms, and all abnormal GNAs were associated with abnormal biopsies. Use of stress GNA uncovered six abnormal ventricles which could have been missed with a rest GNA alone. It has been suggested that: (1) GNA is a reliable monitor of D therapy; (2) an exercise study should be performed when the rest ejection fraction is normal, but is unnecessary when the rest EF is abnormal; (3) all patients with a resting ejection fraction of less than 45%, exclusive of other cardiac disease, should have D discontinued; and (4) endomyocardial biopsy is useful in assessing D cardiotoxicity in patients with other possible causes of an abnormal GNA.

Effects of exercise training on ventricular function in patients with recent myocardial infarction

We evaluated the effects of 6 months of exercise training (bicycle ergometry, walking and jogging) on exercise performance and ventricular function in patients with recent myocardial infarction. Fifteen patients were selected on the basis of myocardial infarction at least 6 weeks but not more than 6 months before the study and age younger than 65 years. The patients were evaluated by maximal treadmill exercise testing and radionuclide angiography at rest and exercise before and after training. Before exercise training, maximal treadmill exercise time ranged from 1.5 to 11 minutes, ejection fraction at rest from 18% and 67% and end-diastolic volume from 108 to 208 ml. The mean EF was 48 +/- 5% (+/- SD) at rest and did not change at maximal exercise (48.5 +/- 5%). All 11 patients who completed the exercise training program achieved a significant training effect, as defined by a reduction in heart rate at 50% maximal pretraining effort or an increase in maximal treadmill time. The mean ejection fraction and end-diastolic volume and wall motion abnormalities at rest and at comparable pretraining exercise work loads and heart rates were not significantly different after training. Despite a wide range of rest and exercise ventricular function, patients with recent uncomplicated myocardial infarcts significantly increased their exercise performance. Because rest and exercise ventricular function were comparable before and after training, improvement in exercise performance probably resulted from training effects on the peripheral vasculature.

Accuracy of diagnosis of coronary artery disease by radionuclide management of left ventricular function during rest and exercise

Rest and exercise radionuclide angiocardiographic measurements of left ventricular function were obtained in 496 patients who underwent cardiac catheterization for chest pain. Two hundred forty-eight of these patients also had an exercise treadmill test. An ejection fraction less than 50% was the abnormality of resting left ventricular function that provided the greatest diagnostic information. In patients with normal resting left ventricular function, exercise abnormalities that were optimal for diagnosis of coronary artery disease were an injection fraction at least 6% less than predicted, an increase greater than 20 ml in end-systolic volume and the appearance of an exercise-induced wall motion abnormality. The sensitivity and specificity of the test were lower in patients who were taking propranolol at the time of study and in patients who failed to achieve an adequate exercise end point. In the 387 patients with an optimal study, the test had a sensitivity of 90% and a specificity of 58%. Radionuclide angiocardiography was more sensitive and less specific than the exercise treadmill test. The high degree of sensitivity of the radionuclide test suggests that it is most appropriately applied to patient groups with a high prevalence of disease, including those considered for cardiac catheterization.

Influence of resting left ventricular function on the left ventricular response to exercise in patients with coronary artery disease

First-pass radionuclide angiocardiography was used to access the left ventricular response to submaximal exercise in 150 patients with coronary artery disease (CAD). To test the hypothesis that resting systolic left ventricular function as determined by left ventricular ejection fraction (LVEF) was a predictor of the hemodynamic response to exercise, the study group included patients with a wide range of resting LVEF (0.12-0.82). The influences of resting LVEF, resting end-diastolic volume, the number of diseased vessels, exercise end point and exercise double product on the change in LVEF (delta LVEF) during exercise were tested using multiple linear regression analyses. Resting LVEF was a highly significant predictor of the delta LVEF (p = 0.0001). Exercise duration was not related to either the resting LVEF or the delta LVEF. For the 112 patients in whom coronary anatomy was known, resting LVEF retained its significance as a predictor of delta LVEF (p = 0.002) even after adjustment for the significance of the extent of CAD (p = 0.0007) and the exercise end point (p = 0.06). Patients with normal resting LVEF showed the most profound decreases in LVEF, the highest frequency of new regional dysfunction and the largest relative increase in end-diastolic volume during exercise. As rest LVEF decreased, the magnitude of the delta LVEF and the frequency of new regional dysfunction decreased. Therefore, left ventricular function at rest is an important determinant of the direction and magnitude of change in left ventricular function during exercise.