A challenge to the evidence behind noise guidelines for UK hospitals

BACKGROUND

Teams assessing hospital noise against international guidelines regularly find that noise exceeds perceived safe levels in clinical settings. The care of sick people may be inherently noisy but recent efforts to tackle the problem propose a wider scope to identify sources and qualities of noise as well as more precision with noise recording.

AIMS

We sought to challenge the scientific evidence cited in the four major documents pertaining to hospital noise in the UK to clarify if evidence of harm from noise included in guidelines is available, contemporary and of high quality.

METHODS

Our team of hearing-health clinicians, acoustic scientists and acoustic engineers have conducted a narrative scoping review focused on critically appraising four of the most cited guidelines against which noise is measured in healthcare settings in the UK.

RESULTS

There is a lack of high-quality evidence for commonly accepted consequences of noise cited in current guidelines.

CONCLUSIONS

The current evidence base for noise guidelines in a healthcare setting is largely based on subjective heterogeneous and inconclusive research. Whilst reduced noise is not disputed as potentially beneficial for patient care, further hypothesis-driven research and interventions assessing the benefits or outcomes of any such intervention should be sought to produce high-quality evidence of relevance on the clinical coalface.

The role of cholecystectomy following endoscopic sphincterotomy and bile duct stone removal

INTRODUCTION

Choledocholithiasis is common, with patients usually treated with endoscopic retrograde cholangiopancreatography (ERCP) and subsequent cholecystectomy to remove the presumed source of common bile duct (CBD) stones. However, previous investigations into the management of patients following ERCP have focused on recurrent CBD stones, negating the risks of cholecystectomy. This article appraises the role of cholecystectomy following successful endoscopic clearance of bile duct stones.

METHODS

Patients undergoing ERCP and CBD clearance for choledocholithiasis at St James's University Hospital January 2015-December 2018 were included. Patients were divided into those who received cholecystectomy and those managed non-operatively. Readmissions, operative morbidity, mortality and treatment costs were investigated.

RESULTS

Eight hundred and forty-four patients received ERCP and CBD clearance with 3.9 years follow-up. Two hundred and nine patients underwent cholecystectomy with 15% requiring complex surgery. Three hundred and seventy-three patients were non-operatively managed. Unplanned readmissions occurred in 15% following ERCP, mostly within two years. There was no difference in readmissions between the two groups. Accounting for the entire patient pathway, non-operative management was less expensive.

CONCLUSIONS

The majority of patients do not require readmission following ERCP for CBD stones, and cholecystectomy did not reduce the risk of readmission. Few patients have recurrent CBD stones, but complex biliary surgery is frequently required. Routine cholecystectomy following ERCP needs to be re-evaluated and a more stratified approach to future risk developed.

The Contribution of Commonly Diagnosed Genetic Disorders to Small for Gestational Age Birth and Subsequent Morbidity and Mortality in Preterm Infants

Objective

Preterm infants born small, vs. appropriate for gestational age (SGA, AGA) are at greater risk for morbidity and mortality. The contribution of genetic disorders to preterm SGA birth, morbidity, and mortality is unknown. We sought to determine the association between genetic disorders and preterm SGA birth, and the association between genetic disorders and morbidity or mortality within preterm SGA infants. We hypothesized that genetic disorders were significantly associated with both.

Study Design

This was a retrospective multicenter cohort study of 409 339 infants, born 23-33 weeks' gestation between 2000 and 2020. The odds of preterm SGA (vs AGA) birth, and the odds of severe morbidity or mortality within SGA preterm infants were determined for infants with genetic disorders, after adjusting for known risk factors.

Results

Genetic disorders were present in 3.0 and 1.3% of SGA and AGA preterm infants respectively; genetic disorders conferred an aOR (95% CI) of 2.06 (1.92, 2.21) of SGA birth. Genetic disorders were present in 4.3 of preterm SGA infants with morbidity or mortality and 2.1% of preterm SGA infants that did not experience morbidity or mortality. Genetic disorders conferred an aOR (95% CI) of 2.12 (2.66, 3.08) of morbidity or mortality.

Conclusions

Genetic disorders are strongly associated with preterm SGA birth, morbidity, and mortality. Clinicians should consider genetic testing of preterm SGA infants, particularly in the setting of other comorbidities or anomalies. Prospective, genomic research is needed to clarify the contribution of genetic disorders to disease in this population.

977 Breaking Out of Tradition: Designing Escape Rooms as Novel Simulation

Aim

The emerging field of gamification, the addition of game play elements to non-game settings, is widely used in business and is increasingly being used in education. Successful methods have included live leader boards and a web-based game solving a protein folding conundrum.

Method

We designed an escape room (ER), incorporating gaming elements, focussing on communication in a surgical environment. A cross over study was delivered to 4th year medical students, comparing traditional simulation. The ER included logic puzzles, hidden clues, padlocked boxes, and surgical skills appropriate to their level. Self-reported engagement and teamwork were recorded, as was observed teamwork and communication skills.

Results

Self-reported engagement was very high for the students compared to more traditional simulation, including better understanding of effective communication strategies. The ER group were less likely to self-identify learning points but structured debrief mitigated this difference.

Conclusions

Gamification techniques can be integrated with good engagement and educational outcomes and should be considered as an adjunct to existing simulation strategy.

971 Gamification of Education; Can Playable Education Result in Better Learning Outcomes?

Aim

Combining traditional simulation (TS) and the emerging field of gamification, to create medical Escape Rooms (ERS) has been used in Nursing to good results but is yet to be widely adopted in medical education. We conducted a pilot study to create ERS for undergraduates to assess their educational value.

Method

Existing Simulation themes of sepsis, post-operative bleeding, trauma, burns and communication in the theatre environment were developed into Escape Rooms by a multidisciplinary team. A cross over study for 4th year students was carried out. Questionnaires were used to evaluate the experience, learning assessed by pre and post quiz and observational tools for teamwork, communication and leadership were utilised.

Results

Qualitative data demonstrated overall good feedback on enjoyment an engagement. Quantitative data collected as pre- and post-exposure learning demonstrated equivocal benefit. Self-assessed teamwork showed equal in all domains and improved in contribution of knowledge and maintaining team focus on the ER group.

Conclusions

Participants find ER enjoyable have similar educational benefits of traditional simulation with the benefits on enhancing non-technical skills amongst a novice group. Escape rooms may be useful as an adjunct to TS particularly at developing non-technical skills.

A cross-disorder dosage sensitivity map of the human genome

Rare copy-number variants (rCNVs) include deletions and duplications that occur infrequently in the global human population and can confer substantial risk for disease. In this study, we aimed to quantify the properties of haploinsufficiency (i.e., deletion intolerance) and triplosensitivity (i.e., duplication intolerance) throughout the human genome. We harmonized and meta-analyzed rCNVs from nearly one million individuals to construct a genome-wide catalog of dosage sensitivity across 54 disorders, which defined 163 dosage sensitive segments associated with at least one disorder. These segments were typically gene dense and often harbored dominant dosage sensitive driver genes, which we were able to prioritize using statistical fine-mapping. Finally, we designed an ensemble machine-learning model to predict probabilities of dosage sensitivity (pHaplo & pTriplo) for all autosomal genes, which identified 2,987 haploinsufficient and 1,559 triplosensitive genes, including 648 that were uniquely triplosensitive. This dosage sensitivity resource will provide broad utility for human disease research and clinical genetics.

1103 How to Report Noise in The Operating Theatre

Introduction

The reporting of operating theatre noise in the surgical literature dates back almost 50 years. The existing standards for noise and sound reporting in healthcare settings is heterogenous and there is a need for greater uniformity of reporting to support our growing understanding of the significance of communication and human factors on surgical performance.

Method

This presentation summarizes the existing Surgical and Acoustic Engineering industrial expertise to provide a narrative review of literature, grey reports and guidelines and then demonstrates appropriate reporting standards during Noise level recording in an operating theatre environment.

Results

We describe LAmax, LA90and LAeq expected levels. We compare our own theatre noise levels against these recommended standards for comparison. This presentation also suggests a suitable “ambient noise” (LAeq 65dB) level over which any communication devices or communication studies should benchmark when developing interventions to overcome noise in the operating theatre.

Conclusions

This paper proposes possible unified reporting standards and expected sound pressure levels against which future studies in this field could benchmark.

Dark Energy Survey Year 1 Results: Cosmological Constraints from Cluster Abundances, Weak Lensing, and Galaxy Correlations

We present the first joint analysis of cluster abundances and auto or cross-correlations of three cosmic tracer fields: galaxy density, weak gravitational lensing shear, and cluster density split by optical richness. From a joint analysis (4×2pt+N) of cluster abundances, three cluster cross-correlations, and the auto correlations of the galaxy density measured from the first year data of the Dark Energy Survey, we obtain Ω_{m}=0.305_{-0.038}^{+0.055} and σ_{8}=0.783_{-0.054}^{+0.064}. This result is consistent with constraints from the DES-Y1 galaxy clustering and weak lensing two-point correlation functions for the flat νΛCDM model. Consequently, we combine cluster abundances and all two-point correlations from across all three cosmic tracer fields (6×2pt+N) and find improved constraints on cosmological parameters as well as on the cluster observable-mass scaling relation. This analysis is an important advance in both optical cluster cosmology and multiprobe analyses of upcoming wide imaging surveys.

Constraints on Dark Matter Properties from Observations of Milky Way Satellite Galaxies

We perform a comprehensive study of Milky Way (MW) satellite galaxies to constrain the fundamental properties of dark matter (DM). This analysis fully incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and marginalizes over uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk. Our results are consistent with the cold, collisionless DM paradigm and yield the strongest cosmological constraints to date on particle models of warm, interacting, and fuzzy dark matter. At 95% confidence, we report limits on (i) the mass of thermal relic warm DM, m_{WDM}>6.5  keV (free-streaming length, λ_{fs}≲10h^{-1}  kpc), (ii) the velocity-independent DM-proton scattering cross section, σ_{0}<8.8×10^{-29}  cm^{2} for a 100 MeV DM particle mass [DM-proton coupling, c_{p}≲(0.3  GeV)^{-2}], and (iii) the mass of fuzzy DM, m_{ϕ}>2.9×10^{-21}  eV (de Broglie wavelength, λ_{dB}≲0.5  kpc). These constraints are complementary to other observational and laboratory constraints on DM properties.

Detection of Cross-Correlation between Gravitational Lensing and γ Rays

In recent years, many γ-ray sources have been identified, yet the unresolved component hosts valuable information on the faintest emission. In order to extract it, a cross-correlation with gravitational tracers of matter in the Universe has been shown to be a promising tool. We report here the first identification of a cross-correlation signal between γ rays and the distribution of mass in the Universe probed by weak gravitational lensing. We use data from the Dark Energy Survey Y1 weak lensing data and the Fermi Large Area Telescope 9-yr γ-ray data, obtaining a signal-to-noise ratio of 5.3. The signal is mostly localized at small angular scales and high γ-ray energies, with a hint of correlation at extended separation. Blazar emission is likely the origin of the small-scale effect. We investigate implications of the large-scale component in terms of astrophysical sources and particle dark matter emission.

Detection of CMB-Cluster Lensing using Polarization Data from SPTpol

We report the first detection of gravitational lensing due to galaxy clusters using only the polarization of the cosmic microwave background (CMB). The lensing signal is obtained using a new estimator that extracts the lensing dipole signature from stacked images formed by rotating the cluster-centered Stokes QU map cutouts along the direction of the locally measured background CMB polarization gradient. Using data from the SPTpol 500  deg^{2} survey at the locations of roughly 18 000 clusters with richness λ≥10 from the Dark Energy Survey (DES) Year-3 full galaxy cluster catalog, we detect lensing at 4.8σ. The mean stacked mass of the selected sample is found to be (1.43±0.40)×10^{14}M_{⊙} which is in good agreement with optical weak lensing based estimates using DES data and CMB-lensing based estimates using SPTpol temperature data. This measurement is a key first step for cluster cosmology with future low-noise CMB surveys, like CMB-S4, for which CMB polarization will be the primary channel for cluster lensing measurements.

The long sitting screening test in elite cyclists

Pelvic rotation during cycling is important because it influences aerodynamics, cycling efficiency and the occurrence of overuse injuries. The aim of this study was to determine whether or not pelvic position in long sitting influences pelvic position during cycling. An observational, cross sectional, within-subjects study design was used. Thirty elite international track and road cyclists participated as subjects and two measures were undertaken. In long sitting, a digital inclinometer was positioned on the lumbosacral junction to give a static measure in degrees of sacral inclination (SI) relative to the horizontal. During active cycling, video analysis of reflective surface markers over the anterior superior iliac spine and posterior superior iliac spine was used to give a measure in degrees of anterior pelvic rotation (APR), by the angle between these two landmarks and the horizontal. No significant linear relationship was found between the two testing positions (r = 0.23, p = 0.22).

Changes in chemical signature and host specificity from larval retrieval to full social integration in the myrmecophilous butterfly Maculinea rebeli

The ant social parasite, Maculinea rebeli shows high levels of host specificity at a regional scale. While 68-88% of caterpillars in the field are adopted by nonhost Myrmica ants, 95-100% of the butterflies emerge from the natural host M. schencki the following year. While retrieval of preadoption caterpillars is specific to the genus Myrmica, it does not explain differential survival with different Myrmica species. We present survival data with host and nonhost Myrmica species suggesting that, with nonhosts (M. sabuleti and M. rubra), survival depends on the physiological state of the colony. We also compared the similarities of the epicuticular surface hydrocarbon signatures of caterpillars that were reared by host and nonhost Myrmica for 3 weeks with those from tending workers. Counterintuitively, the hydrocarbons of postadoption caterpillars were more similar (78%, 73%) to the ant colony profiles of the nonhost species than were caterpillars reared in colonies of M. schencki (42% similarity). However, caterpillars from M. schencki nests that were then isolated for 4 additional days showed unchanged chemical profiles, whereas the similarities of those from nonhost colonies fell to 52 and 56%, respectively. Six compounds, presumably newly synthesized, were detected on the isolated caterpillars that could not have been acquired from M. sabuleti and M. rubra (nor occurred on preadoption caterpillars), five of which were found on the natural host M. schencki. These new compounds may relate to the high rank the caterpillars attain within the hierarchy of M. schencki societies. The same compounds would identify the caterpillars as intruders in non-schencki colonies, where their synthesis appeared to be largely suppressed. The ability to synthesize or suppress additional compounds once adopted explains the pattern of mortalities found among fully integrated caterpillars in Myrmica colonies of different species and physiological states.

Outcomes at 1 year for the first 200 patients fitted with GyneFix at Margaret Pyke Centre

The first 200 women to be fitted with GyneFix at the Margaret Pyke Centre, a National Health Service contraception clinic situated in central London, have been followed up at 1 year after insertion. Removals, expulsions and accidental pregnancies in that first year are recorded. Of the cohort, 80% had a known outcome at 12 months. There was one perforation with the inserter tube, leaving 199 women fitted with GyneFix who contributed 2033 woman-months of follow-up time. We recorded 22 early removals, of which 16 were for heavy or irregular bleeding and/or pain, three were because the women wished to conceive and three for other reasons. In addition there were 16 expulsions at intervals ranging from 1 day to 12 months after insertion. Four of the expulsions were unnoticed by the subjects (they were revealed by amenorrhea of pregnancy in two subjects and lost threads in the other two). There were no pregnancies with the GyneFix in situ. The expulsion rate of 8.4% (confidence interval (CI) 5.2-13.4%) and removal rate for bleeding and/or pain of 9.0% (CI 5.6-14.3%) at 12 months recorded in this cohort fall within acceptable ranges for framed intrauterine devices in a population with a large percentage of nulliparous women. However, they are perhaps not as good as had been anticipated for this revolutionary new intrauterine implant. Possible reasons for this are explored.

The optimal antibiotic combination in a 5-day Helicobacter pylori eradication regimen

BACKGROUND

Current guidelines for Helicobacter pylori eradication recommend 7 days of a proton-pump inhibitor, clarithromycin (C), and either metronidazole (M) or amoxycillin (A). A shorter course would be cheaper and could be as effective.

AIM

This study was designed to investigate the efficacy of three 5-day regimens based on lansoprazole (L).

METHODS

168 dyspepsia patients with H. pylori infection were randomized to receive a 5-day course of either LCM, LAC or CALM, and a 13C-urea breath test was performed after 4 weeks to assess eradication.

RESULTS

160 patients completed the study. Intention-to-treat eradication rates were as follows: LCM 81%, LAC 59%, CALM 88%. LCM and CALM gave significantly better eradication rates than LAC. There was no significant difference in adverse events across the three groups. Logistical regression analysis showed that the specific regimen used and the age of the patient were the only factors influencing eradication outcome.

CONCLUSIONS

Five days of CALM yields acceptable eradication rates, and is cheaper than conventional 7-day proton pump inhibitor-triple therapy. It appears to offer good results in metronidazole-resistant strains of H. pylori. A randomized trial comparing 5-day CALM with conventional 7-day therapy is needed before this regimen can be recommended for routine use.

Clinical and histological associations of cagA and vacA genotypes in Helicobacter pylori gastritis

AIMS

To determine the relation among the cytotoxin associated gene (cagA) and vacuolating cytotoxin gene (vacA) status of Helicobacter pylori isolates, the associated clinical diseases, and the severity and pattern of chronic gastritis.

METHODS

Helicobacter pylori was cultured from gastric biopsies obtained from dyspeptic patients. DNA was extracted from the isolates and the cagA and vacA status determined by the polymerase chain reaction (PCR). The prevalence of the different cagA and vacA genotypes in three clinical groups, duodenal ulcer, gastric ulcer, and non-ulcer dyspepsia was compared. The histological features in sections from two antral and two corpus biopsies were graded by one blinded observer. The grades were compared with age and sex matched groups with different cagA and vacA genotypes, and with duodenal ulcers, or non-ulcer dyspepsia.

RESULTS

Isolates from 161 patients were included. One hundred and nine (68%) harboured a cagA+ strain and 143 (89%) harboured a vacA s1 strain. The prevalence of cagA+ strains in duodenal ulcer patients (94%) was highly significantly greater than in those with non-ulcer dyspepsia (56%). However, of the patients infected with a cagA+ strain, almost equal numbers had non-ulcer dyspepsia or peptic ulceration. Chronic inflammation, polymorph activity, surface epithelial degeneration, atrophy, and intestinal metaplasia were all significantly more severe in the cagA+ than in the cagA- group, whereas only corpus epithelial degeneration was significantly more severe in the vacA s1 group compared with the vacA s2 group. Patients infected with cagA+ strains were almost four times more likely to have antral intestinal metaplasia than cagA- patients. An antral predominant gastritis was present in duodenal ulcer patients compared with matched non-ulcer dyspepsia patients, but this was not attributable to cagA or vacA status.

CONCLUSIONS

Helicobacter pylori strains showing cagA positively and the vacA s1 genotype are associated with more severe gastritis but these virulence factors do not appear to determine the overall pattern. The pattern is closely linked to clinical disease. Therefore, it is likely that the nature of the disease complicating chronic infection is determined by host and environmental factors, while bacterial factors determine the magnitude of the risk of developing such disease.

Evaluation of a three-year urban elementary school tobacco prevention program

The longitudinal study compared effects of varying amounts of tobacco instruction (one, two, and three years) on the knowledge, attitudes, and behavioral intentions of urban elementary students. A three-year, fourth-through-sixth grade tobacco prevention curriculum was developed based on the Centers for Disease Control and Prevention's Guidelines for School Health Programs to Prevent Tobacco Use and Addiction. The curriculum comprised five, 45-minute lessons per year. The same trained instructor taught the curriculum all three years. Six intervention schools were taught the curriculum, and two control schools were not. A 49-item questionnaire was used to assess tobacco knowledge, attitudes, and behavioral intentions. The experimental group's posttest knowledge and attitude scores were significantly higher than the control group's posttest scores. No significant differences occurred in posttest behavioral intention scores between the control and intervention groups.

African-American adults' perceptions of guns and violence

This study examined African-American adults' perceptions of guns and violence. Through a mall intercept type study, 347 adults, ages 20 to 75, responded to a 54-item questionnaire. One third of the respondents claimed they owned one or more types of guns, three fourths had personally known someone who had been shot, more than one third had actually seen someone shot, and one third had a gun pulled on them. While the vast majority (84%) believed guns are too easy to obtain, the majority (62%) also believed that having a gun at home would help protect them. There were no significant differences in perceptions of guns based on age, gender, level of education, or socioeconomic status. The results of this study tend to substantiate the concern and fear of personal harm that African Americans have to contend with on a regular basis. The results also suggest the need for some form of educational intervention and gun safety training in order to help reduce the risk of death and injury among African Americans.

Thrombus with infection in total artificial heart animals

From January 1980 to December 1990, several types of total artificial hearts were implanted into 378 animals. In a retrospective study of these animals, 147 (39%) were found to have thrombus with infection (T&I). The criteria for diagnosis was thrombus formation in the artificial heart and a positive blood culture. The most common pathogen isolated from T&I animals was Pseudomonas species. Concurrent skin lesions and contamination from the pressure lines may be the primary sources of infection, but bacterial translocation from the intestine is another possible route. The main pathological findings at necropsies of artificial heart animals with T&I were associated with sepsis, congestive heart failure, infected thrombus, thromboembolism, and multiple organ infarctions. Most thrombi appeared to have originated from valve junctions and connectors. On the basis of these observations, a possible mechanism for pathogenesis of T&I has been proposed. The results suggest that design improvements and surface modifications to reduce thrombosis are important factors that should be carefully considered. Similarly, it is important to eliminate the route of entry of pathogenic microorganisms. These findings imply that bacterial interaction with thrombus, device related bacterial colonization, and host immunomodulation and gut barrier function following artificial heart implantation need further investigation.

Factors influencing the accuracy of the cardiac output monitoring and diagnostic unit for pneumatic artificial hearts

The Cardiac Output Monitor and Diagnostic Unit (COMDU) has been the most widely used method to noninvasively determine cardiac output in pneumatic ventricles for the past 10 years. Clinical observation has suggested a discrepancy between the COMDU and expected cardiac outputs. In vivo tests verified and quantified this error. The error sources were examined using in vitro test conditions, with both the inflow and outflow, as well as COMDU flow readings, being analyzed. Transducer and calibration error sources were also identified, and the accuracy of the method for determining cardiac output for the in vitro test conditions was quantified. With a more accurate calibration scheme, the in vitro average error was reduced from -16.2% (range of 0.1% to -41.1%) to 0.1% (range 4.8% to -3.65). The major error sources were identified as missed inflow, transducer calibration and drift, and system variance.

Characterization of natural and total artificial heart acceleration

The pulsatile nature of an implanted total artificial heart (TAH) may have several deleterious effects. To define the level of TAH impact, acceleration was measured and compared with that of the natural heart in a series of in vivo and in vitro experiments. In TAH implantations in calves, miniature accelerometers were incorporated onto the housing of a Utah-100 left ventricle. Identical accelerometers were glued to felt pledgets to obtain measurement of radial cardiac acceleration when sewn to the epicardial surface of the natural heart. Measurement of natural and artificial heart acceleration was made both intraoperatively and postoperatively in several animals. Many pumping conditions were also investigated with a similarly instrumented UVAD 85 left ventricle during in vitro testing. The peak natural heart acceleration measured was nearly 2 g both intraoperatively and at rest. Treadmill exercise or epinephrine infusion produced twice the resting peak acceleration value of the natural heart. Artificial heart peak acceleration as great as +/- 100 g was found intraoperatively and postoperatively. Peak TAH acceleration could be reduced by allowing the ventricle to fill fully prior to the start of the next systole, by allowing the ventricle to fully eject prior to the next diastole, or by using a ventricular pressurization waveform that has a smooth contour with a sinusoidal-like profile. The ability to lower TAH acceleration may lead to a reduction in undesirable consequences of TAH implantation.

Anogenital ratio: measure of fetal virilization in premature and full-term newborn infants

To provide normative data, we measured anogenital distances in 115 infants of 25 to 42 weeks gestational age and 10 pregnant women, including anus to fourchette (AF), anus to base of the clitoris (AC), and fourchette to base of the clitoris (FC). All infant measurements showed positive and significant correlations with body surface area, weight, length, and gestational age (P less than 0.001). However, the anogenital ratio (AF/AC) followed a normal distribution and did not correlate with any of the anthropometric variables or age. Mean (+/- SD) value in infants was 0.37 +/- 0.07, and in adults, 0.36 +/- 0.07. An anogenital ratio greater than 0.50 falls outside the 95% confidence limits, suggests labioscrotal fusion, and indicates a need for further evaluation. Because it is independent of body size and gestational age, the anogenital ratio should be useful in diagnosing androgen-induced labioscrotal fusion in both premature and full-term female infants.

A comparison of mydriatic eyedrops in low-weight infants

The pupils of neonates often need to be dilated to examine the retina for retinopathy of prematurity and other disorders. It is known that low-weight infants (less than 1600 grams) are susceptible to systemic hypertension when 10% or 2.5% phenylephrine eye drops are used. To find the safest and best commercially available mydriatic agent in neonates, 30 low-weight infants were divided evenly into three groups. The drops tested were cyclopentolate 0.5% alone, cyclopentolate 0.5% plus mydriacyl 0.5%, and a combination drop of phenylephrine 1% and cyclopentolate 0.2%. There was no clinically significant effect of any of the drops on systolic blood pressure or pulse rate. The cyclopentolate and phenylephrine combination dilated the pupils by a mean of 2.8 mm which was statistically greater than the other groups (P less than 0.01) and had a longer duration of maximal dilation than the other drops (P less than 0.05).

Meal-stimulated gastric acid secretion in infants

Basal acid output and meal-stimulated acid output were measured in newborn infants after nasogastric infusion of 5% glucose and elemental formula, respectively. In six older infants (age range 6 to 31 months), basal acid output was 0.067 +/- 0.017 mmol/kg/hr and maximal acid output was 0.200 +/- 0.028 mmol/kg/hr. Meal-stimulated acid output in four of six older infants was 0.149 +/- 0.038 mmol/kg/hr. In eight healthy newborn infants basal acid output was 0.038 +/- 0.008 mmol/kg/hr; meal-stimulated acid output was 0.064 +/- 0.011 mmol/kg/hr (P less than 0.01). The time course of the secretory response to the elemental formula was as described previously after a protein meal in adults: the rate of acid secretion increased after 20 minutes and remained greater than the basal rate through the remainder of the 90 minute test period. These results demonstrate that in human newborn infants a mixed meal containing protein hydrolysate induces an acid secretory response that is qualitatively similar to but weaker than the response in older infants and adults.

Phagocyte chemotaxis in the perinatal period

Cross-sectional and limited sequential studies of neutrophil and monocyte chemotaxis were done using cells isolated from cord blood and peripheral blood of 2- to 6-day-old neonates and infants at 4 and 6 months of age. These studies show that cord blood phagocyte chemotaxis is comparable to adult values, whereas phagocyte chemotaxis at 2-6 days of age is significantly lower than adult (P less than 0.01) or cord (P less 0.01) chemotaxis values. At 6 months of age, phagocyte chemotaxis is still low compared to adult values (P less than 0.01).

Systemic effects of mydriatics in low weight infants

Two-and-a-half percent phenylephrine eye drops were used in combination with 0.5% tropicamide for routine pupillary dilation in 10 low weight infants. Significant systolic blood pressure elevation was noted in eight of 10 infants. A matched control group dilated with cycloplegics alone did not show a significant rise in systolic blood pressure. The mean change in pupillary dilation in the study group was 3.9 mm compared with 3.1 mm in the control group. This difference is not statistically significant. We therefore recommend that cycloplegic agents alone be used for pupillary dilation in these high risk infants.