Social Deprivation and the Association With Survival Following Fenestrated Endovascular Aneurysm Repair.

BACKGROUND: Social deprivation is associated with poor clinical outcomes. It is known to have an impact on length of stay and post-operative mortality across a number of other surgical specialties. This study evaluates the impact of social deprivation on outcomes following fenestrated endovascular aneurysm repair (FEVAR). METHODS: All elective FEVARs performed between 2010 and 2018 at a tertiary vascular center were analyzed. Deprivation (index of multiple deprivation [IMD]) data was sourced from the English indices of deprivation 2019, by postcode. Primary outcome was overall survival by Kaplan-Meier. Secondary outcomes included length of hospital stay (LOS) and complications. Cox-proportional hazard analyses were conducted. RESULTS: Some 132 FEVAR patients were followed-up for 3.7 (SD 2.2) years. Fifty-seven patients lived in areas with high levels of deprivation (IMD 1-3), 34 in areas with moderate deprivation (IMD 4-6) and 41 in areas with the lowest level (IMD 7-10) of deprivation. Groups were comparable for Age, BMI, AAA diameter and co-morbidity. A higher proportion of patients from deprived areas had renal failure (15% [26.3%] vs. 9% [11.8%] P = 0.019) but no overall difference in procedure time was observed (200 min [155-250] vs. 180 min [145-240] P = 0.412). Kaplan-Meier analysis demonstrated significantly poorer survival for patients living in areas with high levels of deprivation (IMD 1-3) (P = 0.03). Mortality was comparable for IMD 4-6 and 7-10 groups. Patients from the most deprived areas had longer hospital stay (6 days [4-9] vs. 5 [3-7] P = 0.005) and higher all-cause complication rates (21 [36.8%] vs. 14 [18.4%] P = 0.02). Decreasing IMD was associated with worse survival (HR -0.85 [0.75-0.97] [P = 0.02]). CONCLUSIONS: Social deprivation was associated with increased mortality, length of stay and all-cause complication rates in patients undergoing FEVAR for complex abdominal aortic aneurysm (AAA). These results may help direct preoptimization measures to improve outcomes in higher risk sub-groups.

Editor's Choice - Systematic Review and Meta-Analysis of Wound Adjuncts for the Prevention of Groin Wound Surgical Site Infection in Arterial Surgery.

OBJECTIVE: Groin incision surgical site infections (SSIs) following arterial surgery are common and are a source of considerable morbidity. This review evaluates interventions and adjuncts delivered immediately before, during, or after skin closure, to prevent SSIs in patients undergoing arterial interventions involving a groin incision. DATA SOURCES: MEDLINE, EMBASE, and CENTRAL databases were searched. REVIEW METHODS: This review was undertaken according to established international reporting guidelines and was registered prospectively with the International prospective register of systematic reviews (CRD42020185170). The MEDLINE, EMBASE, and CENTRAL databases were searched using pre-defined search terms without date restriction. Randomised controlled trials (RCTs) and observational studies recruiting patients with non-infected groin incisions for arterial exposure were included; SSI rates and other outcomes were captured. Interventions reported in two or more studies were subjected to meta-analysis. RESULTS: The search identified 1 532 articles. Seventeen RCTs and seven observational studies, reporting on 3 747 patients undergoing 4 130 groin incisions were included. A total of seven interventions and nine outcomes were reported upon. Prophylactic closed incision negative pressure wound therapy (ciNPWT) reduced groin SSIs compared with standard dressings (odds ratio [OR] 0.34, 95% CI 0.23 - 0.51; p < .001, GRADE strength of evidence: moderate). Local antibiotics did not reduce groin SSIs (OR 0.60 95% CI 0.30 - 1.21 p = .15, GRADE strength: low). Subcuticular sutures (vs. transdermal sutures or clips) reduced groin SSI rates (OR 0.33, 95% CI 0.17 - 0.65, p = .001, GRADE strength: low). Wound drains, platelet rich plasma, fibrin glue, and silver alginate dressings did not show any significant effect on SSI rates. CONCLUSION: There is evidence that ciNPWT and subcuticular sutures reduce groin SSI in patients undergoing arterial vascular interventions involving a groin incision. Local antibiotics did not reduce groin wound SSI, although the strength of this evidence is lower. No other interventions demonstrated a significant effect.

Reducing the risk of venous thromboembolism following superficial endovenous treatment: A UK and Republic of Ireland consensus study.

OBJECTIVES: Venous thromboembolism is a potentially fatal complication of superficial endovenous treatment. Proper risk assessment and thromboprophylaxis could mitigate this hazard; however, there are currently no evidence-based or consensus guidelines. This study surveyed UK and Republic of Ireland vascular consultants to determine areas of consensus. METHODS: A 32-item survey was sent to vascular consultants via the Vascular and Endovascular Research Network (phase 1). These results generated 10 consensus statements which were redistributed (phase 2). 'Good' and 'very good' consensus were defined as endorsement/rejection of statements by >67% and >85% of respondents, respectively. RESULTS: Forty-two consultants completed phase 1. This generated seven statements regarding risk factors mandating peri-procedural pharmacoprophylaxis and three statements regarding specific pharmacoprophylaxis regimes. Forty-seven consultants completed phase 2. Regarding venous thromboembolism risk factors mandating pharmacoprophylaxis, 'good' and 'very good' consensus was achieved for 5/7 and 2/7 statements, respectively. Regarding specific regimens, 'very good' consensus was achieved for 3/3 statements. CONCLUSIONS: The main findings from this study were that there was 'good' or 'very good' consensus that patients with any of the seven surveyed risk factors should be given pharmacoprophylaxis with low-molecular-weight heparin. High-risk patients should receive one to two weeks of pharmacoprophylaxis rather than a single dose.

Editor's Choice - Acute Kidney Injury (AKI) in Aortic Intervention: Findings From the Midlands Aortic Renal Injury (MARI) Cohort Study.

OBJECTIVES: The incidence of acute kidney injury (AKI) after open (OAR) or endovascular (EVAR) aortic repair is unknown. This research assessed the proportion of patients who develop AKI after aortic intervention using validated criteria, and explored AKI risk factors. METHODS: This was a multicentre national prospective cohort study. Eleven centres recruited patients undergoing EVAR or OAR (September 2017-December 2018). Serum creatinine (SCr) and urine outputs were measured over a minimum of 48 h or throughout the index inpatient stay to define post-operative AKI using the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Renal decline at 30 days was calculated using estimated glomerular filtration rate (eGFR) and the Major Adverse Kidney Events (MAKE) 30 day composite endpoint (consisting of: death, new dialysis, > 25% eGFR decline). RESULTS: 300 patients (mean age: 71 years, standard deviation [SD] 4 years; 9% females) were included, who underwent: infrarenal endovascular aneurysm repair (EVAR) 139 patients, fenestrated EVAR (fEVAR) 30, branched EVAR (bEVAR) seven, infrarenal open aneurysm repair (OAR) 98, juxtarenal OAR 26. Overall, 24% of patients developed stage 1 AKI (defined at 48 h as per KDIGO), 2.7% stage 2 AKI and 1% needed renal replacement therapy before discharge. AKI proportions per intervention were: infrarenal EVAR 18%; fEVAR 27%; bEVAR 71%; infrarenal OAR 41%; juxtarenal OAR 63%. Older age (odds ratio [OR] 1.44 for EVAR, 1.58 for OAR), lower baseline eGFR (OR 0.88 EVAR, 0.74 OAR), and ischaemic heart disease (OR 4.42 EVAR, 5.80 OAR) were the main predictors of AKI for infrarenal EVAR and OAR. Overall, 24% developed the MAKE30 endpoint. All patients who died (0.6%) or developed a major cardiac event (5.6%) at one year had developed AKI. CONCLUSION: AKI and short term renal decline after aortic intervention are common. Age, renal function, and cardiovascular disease are the main risk factors. Research should now focus on AKI prevention in this high risk group.

A Randomised Controlled Trial Comparing Three Different Radiofrequency Technologies: Short-Term Results of the 3-RF Trial.

OBJECTIVE: To date there has been no comparison of outcomes of endovenous radiofrequency (RF) devices. The 3-RF trial is the first randomised controlled trial of three commercially available RF ablation technologies. METHODS: Patients were recruited [182/302 patients with great saphenous vein (GSV) incompetence] into a prospective double blind randomised trial of Venefit, radiofrequency induced thermal therapy (RFITT), and endovenous radiofrequency (EVRF). The primary outcome measure was GSV closure (total/partial/failed) at six months. Secondary outcome measures included ablation times, complications, pain scores, analgesia requirements, and quality of life (QoL) scores to 12 months. RESULTS: Patients treated [180: Venefit (57), RFITT (64), EVRF (59)] were matched for age, sex, and vein characteristics. At six months, complete GSV closure was significantly better after Venefit and RFITT treatment (100% and 98%, respectively) compared with EVRF treatment (79%, p < .001). Mean treatment time was significantly faster for RFITT than for Venefit and EVRF (p < .0001). Euroqol 5D (EQ5D) visual analogue score (VAS) did not differ between groups at any time point. The only difference between groups in EQ5D domain scores was for the pain/discomfort domain at two weeks when significantly fewer EVRF patients reported no problems compared with Venefit and RFITT. This difference had disappeared at six and 12 months. The Aberdeen Varicose Vein Questionnaire (AVVQ) improved for all groups at six and 12 months compared with pre-treatment levels; however, there was no significant difference between groups. CONCLUSION: Compared with Venefit and RFITT, EVRF was associated with significant failure of truncal ablation at six months; however, clinical outcomes did not differ significantly at 12 months. clinicaltrials.gov identifier: NCT02441881, NHS Health Research Authority (Hampstead Research Ethics Committee) number: 14/LO/1232.

The electronic complexity of the ground-state of the FeMo cofactor of nitrogenase as relevant to quantum simulations.

We report that a recent active space model of the nitrogenase FeMo cofactor, proposed in the context of simulations on quantum computers, is not representative of the electronic structure of the FeMo cofactor ground-state. A more representative model does not affect much certain resource estimates for a quantum computer such as the cost of a Trotter step, while strongly affecting others such as the cost of adiabatic state preparation. Thus, conclusions should not be drawn from the complexity of quantum or classical simulations of the electronic structure of this system in this active space. We provide a different model active space for the FeMo cofactor that contains the basic open-shell qualitative character, which may be useful as a benchmark system for making resource estimates for classical and quantum computers.

Study protocol for the groin wound infection after vascular exposure (GIVE) audit and multicentre cohort study.

INTRODUCTION: Surgical site infections (SSIs) following groin incision for arterial exposure are commonplace and a significant cause of morbidity and mortality following major arterial surgery. Published incidence varies considerably. The primary aim of GIVE will be to compare individual units' practice with established guidelines from The National Institute for Health and Care Excellence (NICE). Secondary aims will be to describe the contemporary rate of SSI in patients undergoing groin incision for arterial exposure, to identify risk factors for groin wound infection, to examine the value of published tools in the prediction of SSI, to identify areas of equipoise which could be examined in future efficacy/effectiveness trials and to compare UK SSI rates with international centres. METHODS AND ANALYSIS: This international, multicentre, prospective observational study will be delivered via the Vascular and Endovascular Research Network (VERN). Participating centres will identify all patients undergoing clean emergency or elective groin incision(s) for arterial intervention during a consecutive 3-month period. Follow up data will be captured at 90 days after surgery. SSIs will be defined according to the Centres for Disease Control and Prevention (CDC) criteria. Data will be gathered centrally using an anonymised electronic data collection tool or secure email transfer. ETHICS AND DISSEMINATION: This study will be registered as a clinical audit at all participating UK centres; research ethics approval is not required. National leads will oversee the appropriate registration and approvals in countries outside the UK as required. Site specific reports of SSI rates will be provided to each participating centre. Study results will be disseminated locally at each site, publicised on social media and submitted for peer-reviewed publication.

The Transposed Femoral Vein Fistula: The Native Choice in Desperate Vascular Access.

BACKGROUND: This is a review of our experience in creating transposed femoral vein (TFV) fistulas and some of the lessons we have learnt while performing this challenging procedure over the last 5 years. METHODS: This is retrospective review of patients who underwent TFV fistula formation between January 2013 and December 2017. RESULTS: Fifteen patients underwent FV fistula formation with 4 cases being excluded from analysis. Median follow-up was 1.17 years (interquartile range 0.19-3.59 years). Primary and primary-assisted patency rates were 75% and 100% at 6 months, respectively, and 66.7% and 100% at 1 year. CONCLUSIONS: Our patient group showed good fistula patency at 1 year and did not experience any incidence of ischemic steal syndrome. We believe this to be due to careful preoperative patient assessment and meticulous surgical technique. Our experience suggests that such procedures should be performed by surgeons with vascular expertise wherever possible to reduce the incidence of complications.

Diabetes mellitus and abdominal aortic aneurysms: A review of the mechanisms underlying the negative relationship.

INTRODUCTION: Diabetes mellitus appears to be negatively associated with abdominal aortic aneurysm; however, the mechanisms underlying this relationship remain poorly understood. The aim of this article is to provide a comprehensive review of the currently understood biological pathways underlying this relationship. METHODS: A review of the literature ('diabetes' OR 'hyperglycaemia' AND 'aneurysm') was performed and relevant studies grouped into biological pathways. RESULTS: This review identified a number of biological pathways through which diabetes mellitus may limit the presence, growth and rupture of abdominal aortic aneurysms. These include those influencing extracellular matrix volume, extracellular matrix glycation, the formation of advanced glycation end-products, inflammation, oxidative stress and intraluminal thrombus biology. In addition, there is an increasing evidence to suggest that the medications used to treat diabetes can also limit the development and progression of abdominal aortic aneurysms. CONCLUSION: The negative association between diabetes and abdominal aortic aneurysm is robust. Future studies should attempt to target the pathways identified in this review to develop novel therapeutic agents aimed at slowing or even halting aneurysm progression.

Investigation of the ozone formation reaction pathway: Comparisons of full configuration interaction quantum Monte Carlo and fixed-node diffusion Monte Carlo with contracted and uncontracted MRCI.

The association/dissociation reaction path for ozone (O2 + O ↔ O3) is notoriously difficult to describe accurately using ab initio electronic structure theory, due to the importance of both strong and dynamic electron correlations. Experimentally, spectroscopic studies of the highest lying recorded vibrational states combined with the observed negative temperature dependence of the kinetics of oxygen isotope exchange reactions confirm that the reaction is barrierless, consistent with the latest potential energy surfaces. Previously reported potentials based on Davidson-corrected internally contracted multireference configuration interaction (MRCI) suffer from a spurious reef feature in the entrance channel even when extrapolated towards the complete basis set limit. Here, we report an analysis of comparisons between a variety of electronic structure methods including internally contracted and uncontracted MRCI (with and without Davidson corrections), as well as full configuration interaction quantum Monte Carlo, fixed-node diffusion Monte Carlo, and density matrix renormalization group.

Why Quantum Coherence Is Not Important in the Fenna-Matthews-Olsen Complex.

We develop and present an improvement to the conventional technique for solving the Hierarchical Equations of Motion (HEOM), which can reduce the memory cost by up to 75% while retaining the same (or even better) convergence rate and accuracy. This allows for a full calculation of the population dynamics of the 24-site FMO trimer for long time scales with very little effort, and we present the first fully converged, exact results for the 7-site subsystem of the monomer, and for the full 24-site trimer. We then show where our exact 7-site results deviate from the approximation of Ishizaki and Fleming [A. Ishizaki and G. R. Fleming, Proc. Natl. Acad. Sci. U.S.A., 2009, 106, 17255]. Our exact results are then compared to calculations using the incoherent Förster theory, and it is found that the time scale of energy transfer is roughly the same, regardless of whether or not coherence is considered. This means that coherence is not likely to improve the efficiency of the transfer. In fact, the incoherent theory often tends to overpredict the rates of energy transfer, suggesting that, in some cases, quantum coherence may actually slow the photosynthetic process.

Mapping the space of genomic signatures.

We propose a computational method to measure and visualize interrelationships among any number of DNA sequences allowing, for example, the examination of hundreds or thousands of complete mitochondrial genomes. An "image distance" is computed for each pair of graphical representations of DNA sequences, and the distances are visualized as a Molecular Distance Map: Each point on the map represents a DNA sequence, and the spatial proximity between any two points reflects the degree of structural similarity between the corresponding sequences. The graphical representation of DNA sequences utilized, Chaos Game Representation (CGR), is genome- and species-specific and can thus act as a genomic signature. Consequently, Molecular Distance Maps could inform species identification, taxonomic classifications and, to a certain extent, evolutionary history. The image distance employed, Structural Dissimilarity Index (DSSIM), implicitly compares the occurrences of oligomers of length up to k (herein k = 9) in DNA sequences. We computed DSSIM distances for more than 5 million pairs of complete mitochondrial genomes, and used Multi-Dimensional Scaling (MDS) to obtain Molecular Distance Maps that visually display the sequence relatedness in various subsets, at different taxonomic levels. This general-purpose method does not require DNA sequence alignment and can thus be used to compare similar or vastly different DNA sequences, genomic or computer-generated, of the same or different lengths. We illustrate potential uses of this approach by applying it to several taxonomic subsets: phylum Vertebrata, (super)kingdom Protista, classes Amphibia-Insecta-Mammalia, class Amphibia, and order Primates. This analysis of an extensive dataset confirms that the oligomer composition of full mtDNA sequences can be a source of taxonomic information. This method also correctly finds the mtDNA sequences most closely related to that of the anatomically modern human (the Neanderthal, the Denisovan, and the chimp), and that the sequence most different from it in this dataset belongs to a cucumber.

Outcomes Following Limb Crossing in Endovascular Aneurysm Repairs.

BACKGROUND: Crossing the limbs of the stent during endovascular aneurysm repair (EVAR) is often used to aid cannulation of the contralateral limb. This study assessed outcomes following the use of this technique. METHODS: Retrospective review of crossed (n = 43) and uncrossed (n = 269) EVARs was performed at a tertiary vascular center over 5 years. Primary end points were graft limb occlusion (GLO), endoleak, and sac expansion rates. Indications for limb crossing were also assessed. RESULTS: Two-year GLO (P = .34) and type 1 endoleak (P = .413) rates were similar between groups. Patients undergoing crossed EVAR experienced more type 2 endoleaks (P = .002) at 24 months but no increase in sac expansion rates was observed (P = .275). Thirty-day (P = .57) and late (P = .268) mortalities were similar between groups. The main indication for limb crossing was distal aortic angulation (48.8%). CONCLUSIONS: Crossed EVAR does not increase the risk of GLOs or clinically significant endoleaks. Further studies are needed to determine the effect on type 2 endoleak rates.

Aneurysm global epidemiology study: public health measures can further reduce abdominal aortic aneurysm mortality.

BACKGROUND: Contemporary data from Western populations suggest steep declines in abdominal aortic aneurysm (AAA) mortality; however, international trends are unclear. This study aimed to investigate global AAA mortality trends and to analyze any association with common cardiovascular risk factors. METHODS AND RESULTS: AAA mortality (1994-2010) using International Classification of Diseases codes were extracted from the World Health Organization mortality database and age standardized. The World Health Organization InfoBase and International Mortality and Smoking Statistics provided risk factor data. Nineteen World Health Organization member states were included (Europe, 14; Australasia, 2; North America, 2; Asia, 1). Regression analysis of temporal trends in cardiovascular risk factors (1946-2010) was done independently for correlations to AAA mortality trends. Global AAA mortality trends show substantial heterogeneity, with the United States and United Kingdom recording the greatest national decline, whereas internationally, male individuals and those <75 years of age demonstrated the greatest reductions. AAA mortality has increased in Hungary, Romania, Austria, and Denmark; therefore, the mortality decline is not universal. A positive linear relationship exists between global trends in systolic blood pressure (P≤0.03), cholesterol (P≤0.03), and smoking prevalence (P≤0.02) in males and females. Body mass index demonstrated a negative linear association with AAA mortality (P≤0.007), whereas fasting blood glucose showed no association. CONCLUSIONS: AAA mortality has not declined globally, and this study reveals that differences between nations can be explained by variations in traditional cardiovascular risk factors. Declines in smoking prevalence correlate most closely with declines in AAA mortality, and a novel obesity paradox has been identified that requires further investigation. Public health measures could therefore further reduce global AAA mortality, with greatest benefits in the younger age group.

Effect of anticoagulation and antiplatelet therapy on incidence of endoleaks and sac size expansions after endovascular aneurysm repair.

BACKGROUND: The effects of anticoagulation or antiplatelet therapy on the incidence of endoleak and aneurysm sac size after endovascular aneurysm repair (EVAR) are unclear. This study aims to determine whether these therapies affect the incidence of endoleaks or sac size expansions after EVAR. METHODS: The case notes of 407 patients (367 men and 40 women, mean age 74.7 years) who underwent elective EVAR between January 2006 and November 2011 were reviewed for medication history and EVAR-related outcomes. RESULTS: The median follow-up period was 18 months. There were 45 (11.1%) patients on warfarin (WA), 292 (71.7%) on antiplatelet therapy (AT) (aspirin, clopidogrel, or dipyridamole modified release), and 70 (17.2%) on no anticoagulation or antiplatelet therapy (NA). During the study period, 51 (12.5%) endoleaks were documented, 8 type I (AT = 6, NA = 0, and WA = 2) and 42 type II (AT = 31, NA = 9, and WA = 2). Medication did not significantly affect the incidence of type I (P = 0.24) (based on chi-squared analysis), type II (P = 0.33), or type III (P = 0.82) endoleaks, or sac expansions (P = 0.95). CONCLUSIONS: Warfarin and antiplatelet therapies are not associated with increased incidence of postoperative endoleaks or aneurysm sac expansion after EVAR. The data in this study support safe use of anticoagulant and antiplatelet medications in patients undergoing EVAR.

Clinical and histological outcomes following living-related liver transplantation in children.

OBJECTIVES: Living-related liver transplantation (LRLT) was developed to increase the donor pool of size-matched organs for children. In the UK only one centre performed LRLT between 1993 and 2008. This study reports the clinical and histological outcomes following adult-to-paediatric LRLT at our centre. METHODS: Forty-six LRLTs were reviewed. Recipients had a mean age, weight and PELD score of 2.4years (range 0.5-11years), 11.0kg (3.7-32.3kg) and 11.7 (-20.3 to 49.1) respectively. The incidence of post-transplant paediatric morbidity, abnormal liver function tests and histological abnormalities was reviewed. RESULTS: Patient and graft survival rates were 97.8%, 95.1% and 95.1%, and 97.8%, 92.1% and 71.7% at 1, 5 and 10years post-transplant respectively. Three children were re-transplanted at 44, 100 and 119months post-transplant. Nine children developed neuropsychological problems, 6 experienced educational difficulties, 5 developed post-transplant lymphoproliferative disorder and 5 suffered height or weight growth<2 centile. Normal LFTs were found in 41.7%, 50%, 68% and 64.7% of children at median follow-up of 6, 13, 61 and 85months respectively. Liver histology showed hepatitis, acute rejection, non-specific changes, biliary pathology, vascular pathology and chronic rejection in 32.9%, 29.5%, 13.4%, 10.1%, 6% and 2% of biopsies respectively. CONCLUSIONS: The prevalence of paediatric morbidity and histological abnormalities emphasize the need for specialist and long-term follow-up following LRLT in children.

End tidal carbon dioxide levels during the resuscitation of prematurely born infants.

BACKGROUND: Successful resuscitation of prematurely born infants is dependent on achieving adequate alveolar ventilation and vasodilation of the pulmonary vascular bed. Elevation of end-tidal carbon dioxide (ETCO(2)) levels may indicate pulmonary vasodilation. AIMS: This research aims to study the temporal changes in ETCO(2) levels and the infant's respiratory efforts during face mask resuscitation in the labour suite, and to determine if the infant's first inspiratory effort was associated with a rise in the ETCO(2) levels, suggesting pulmonary vasodilation had occurred. STUDY DESIGN: This study is an observational one. SUBJECTS: The subjects of the study are forty infants with a median gestational age of 30 weeks (range 23-34). OUTCOME MEASURES: Inflation pressures, expiratory tidal volumes and ETCO(2) levels were measured. RESULTS: The median expiratory tidal volume of inflations prior to the onset of the infant's respiratory efforts (passive inflations) was lower than that of the inflation associated with the first inspiratory effort (active inflation) (1.8 (range 0.1-7.3) versus 6.3 ml/kg (range 1.9-18.4), p<0.001), as were the median ETCO(2) levels (0.3 (range 0.1-2.1) versus 3.4 kPa (0.4-11.5), p<0.001). The median expiratory tidal volume (4.5 ml/kg (range 0.5-18.3)) and ETCO(2) level (2.2 kPa (range 0.3-9.3)) of the two passive inflations following the first active inflation were also higher than the median expiratory tidal volume and ETCO(2) levels of the previous passive inflations (p<0.001, p<0.0001 respectively). CONCLUSION: These results suggest that during face mask resuscitation, improved carbon dioxide elimination, likely due to pulmonary vasodilation, occurred with the onset of the infant's respiratory efforts.

The first five inflations during resuscitation of prematurely born infants.

OBJECTIVE: To study the first five inflations during the resuscitation of prematurely born infants and whether the infant's inspiratory efforts influenced the expired tidal volume. DESIGN: Prospective observational study. SETTING: Two tertiary perinatal centres. PATIENTS: Thirty infants, median gestational age 30 (23-34) weeks. INTERVENTIONS: The first five inflations delivered via a face mask and t-piece device were examined using respiratory function monitoring. MAIN OUTCOME MEASURES: Inflation pressures, inflation times and expiratory volumes were recorded and comparison made of inflations during which the infant made an inspiratory effort (active inflation) or did not (passive inflation). RESULTS: Overall, the median expired tidal volume was 2.5 (0-19.8) ml/kg and was lower for passive (median 2.1 ml/kg, range 0-19.8 ml/kg) compared with active (median 5.6 ml/kg, range 1.2-12.2 ml/kg) inflations (ratio of geometric means 1.85, 95% CI 1.18 to 28%) (p=0.007). Overall, the median face mask leak was 54.5% and was lower for active (34.5%) compared with passive (60.7%) inflations (mean difference in % leak: 12.4%, 95% CI 0.9 to 24%) (p=0.0354). There was a significant positive correlation between the expiratory volumes and the inflation pressures (R2 between subjects 0.19, p=0.04) and a negative correlation between the expiratory tidal volumes and the face mask leaks (R2 between subjects=0.051, p<0.001), but there was no significant correlation between the inflation times and the expiratory tidal volumes. CONCLUSION: The expired tidal volume, inflation pressures and times during the first five inflations during resuscitation were variable. The expired tidal volumes were significantly greater if the infant inspired during the inflation.