Enhancing central blood pressure accuracy through statistical modeling: A proof-of-concept study.

Background: Non-invasive estimation of central blood pressure (BP) may have better prognostic value than brachial BP. The accuracy of central BP is limited in certain populations, such as in females and the elderly. This study aims to examine whether statistical modeling of central BP for clinical and hemodynamic parameters results in enhanced accuracy. Methods: This study is a cross-sectional analysis of 500 patients who underwent cardiac catheterization. Non-invasive brachial cuff and central BP were measured simultaneously to invasive aortic systolic BP (AoSBP). Central BP was calibrated for brachial systolic (SBP) and diastolic BP (Type I calibration; C1SBP) or brachial mean and diastolic BP (Type II calibration; C2SBP). Differences between central SBP and the corresponding AoSBP were assessed with linear regression models using clinical and hemodynamic parameters. These parameters were then added to C1SBP and C2SBP in adjusted models to predict AoSBP. Accuracy and precision were computed in the overall population and per age or sex strata. Results: C1SBP underestimated AoSBP by 11.2 mmHg (±13.5) and C2SBP overestimated it by 6.2 mmHg (±14.8). Estimated SBP amplification and heart rate were the greatest predictors of C1- and C2-AoSBP accuracies, respectively. Statistical modeling improved both accuracy (0.0 mmHg) and precision (±11.4) but more importantly, eliminated the differences of accuracy seen in different sex and age groups. Conclusion: Statistical modeling greatly enhances the accuracy of central BP measurements and abolishes sex- and age-based differences. Such factors could easily be implemented in central BP devices to improve their accuracy.

Diuretic combinations in critically ill patients with respiratory failure: A systematic review and meta-analysis.

BACKGROUND: In patients with respiratory failure, loop diuretics remain the cornerstone of the treatment to maintain fluid balance, but resistance is common. AIM: To determine the efficacy and safety of common diuretic combinations in critically ill patients with respiratory failure. METHODS: We searched MEDLINE, Embase, Cochrane Library and PROSPERO for studies reporting the effects of a combination of a loop diuretic with another class of diuretic. A meta-analysis using mean differences (MD) with 95% confidence interval (CI) was performed for the 24-h fluid balance (primary outcome) and the 24-h urine output, while descriptive statistics were used for safety events. RESULTS: Nine studies totalling 440 patients from a total of 6510 citations were included. When compared to loop diuretics alone, the addition of a second diuretic is associated with an improved negative fluid balance at 24 h [MD: -1.06 L (95%CI: -1.46; -0.65)], driven by the combination of a thiazide plus furosemide [MD: -1.25 L (95%CI: -1.68; -0.82)], while no difference was observed with the combination of a loop-diuretic plus acetazolamide [MD: -0.40 L (95%CI: -0.96; 0.16)] or spironolactone [MD: -0.65 L (95%CI: -1.66; 0.36)]. Heterogeneity was high and the report of clinical and safety endpoints varied across studies. CONCLUSION: Based on limited evidence, the addition of a second diuretic to a loop diuretic may promote diuresis and negative fluid balance in patients with respiratory failure, but only when using a thiazide. Further larger trials to evaluate the safety and efficacy of such interventions in patients with respiratory failure are required.

Factors Associated With the Use of Hypothermic Machine Perfusion in Kidney Transplant Recipients: A Multicenter Retrospective Cohort Study.

Background: Delayed graft function (DGF) is associated with an increased risk of graft loss. The use of cold hypothermic machine perfusion (HMP) has been shown to reduce the incidence of DGF in kidney transplant recipients (KTRs), especially when extended-criteria donors (ECDs) are used. HMP can also improve graft survival. However, there is a paucity of data on the determinants of HMP use in clinical practice. Objective: We aimed to determine the factors associated with the use of HMP in a cohort of donors and KTRs. Design: Multicenter retrospective cohort study. Setting: 5 transplant centers in Quebec. Patients: 159 neurologically deceased donors (NDD) and 281 KTR. Measurements: Use of HMP. Methods: We collected data on consecutive NDD admitted to a dedicated donor unit in a single university-affiliated center and their KTRs between June 2013 and December 2018 in 5 adult transplant centers across the province of Quebec, Canada. All organs were recovered in a single hospital center where a HMP device was available for every organ recovered and the decision to use HMP was left at the discretion of the procurement surgeon. Generalized estimating equations were used to predict the use of HMP. Results: The cohort included 159 NDDs and their 281 KTRs. Thirty-three percent of donors were ECDs, and 59% of KTRs received organs placed on HMP. The median cold ischemia time (CIT) was 12.5 (IQR 7.9-16.3) hours. In univariate analysis, none of the donors' characteristics were associated with the use of HMP. ECD represented 33% of KTR on HMP vs 35% of those not placed on HMP (P = .77). In univariate analysis, the use of HMP was associated with KTR race (non-Caucasian), longer CIT, use of basiliximab/alemtuzumab, year of transplant, and transplant center. The use of HMP varied largely across transplant centers, ranging from 15% to 82%. In multivariate analysis, use of HMP was associated with longer CIT (odds ratio [OR] 1.15, 95% confidence interval [CI] = 1.07-1.25), transplant center as well as transplantations performed after 2013. Limitations: One dedicated donor unit including NDD only, absence of specific data on surgeons' experience and personal or logistic reasons for using or not HMP. Conclusions: We found that use of HMP remains low and varies largely across transplant centers. The use of HMP was strongly associated with the transplant center where the surgeons practiced, suggesting that surgeon preference/training plays an important role in determining the use of HMP. Availability of HMP at the time of organ procurement might also be limited by logistic issues such as difficulty in returning the device. Further studies aimed at determining the reasons underlying the barriers precluding the use of HMP could help increasing its use and improve transplant outcomes.

Contexte: Les retards dans la reprise de fonction du greffon (RRFG) sont associés à un risque accru d'échec de la greffe. Il a été démontré que la perfusion hypothermique mécanisée (PHM) peut réduire l'incidence d'un RRFG chez les receveurs d'une greffe rénale (RGR), particulièrement dans les cas où des donneurs à critères étendus (DCÉ) sont impliqués. La PHM pourrait également améliorer la survie du greffon. Il existe cependant peu de données sur les facteurs déterminant l'utilisation de la PHM dans la pratique clinique. Objectifs: Déterminer les facteurs associés à l'utilisation de la PHM dans une cohorte de donneurs et de RGR. Type d'étude: Étude de cohorte rétrospective multicentrique. Cadre: Cinq centres de transplantation au Québec. Sujets: L'étude a inclus 159 donneurs neurologiquement décédés (DND) et 281 RGR. Mesures: L'utilisation de la PHM. Méthodologie: Nous avons recueilli les données de DND consécutifs admis entre juin 2013 et décembre 2018 dans une unité spécialisée dans le don d'organes d'un centre hospitalier universitaire, de même que les données de leurs RGR respectifs. Les sujets provenaient de cinq centres de transplantation pour adultes de la province de Québec, au Canada. Tous les organes ont été prélevés dans un centre hospitalier où un dispositif de PHM était disponible pour chaque organe prélevé, et la décision de recourir à la PHM a été laissée à la discrétion du chirurgien chargé du prélèvement. Des équations d'estimation généralisées ont été employées pour prédire l'utilisation de la PHM. Résultats: La cohorte était composée de 159 DND et de leurs 281 RGR. Les DCÉ constituaient 33 % des DND et 59 % des RGR avaient reçu un organe placé sur PHM. La durée médiane de l'ischémie froide (DmIF) était de 12,5 heures (ÉIQ: 7,9-16,3 heures). Dans l'analyse univariée, aucune des caractéristiques des donneurs n'a été associée à l'utilisation de la PHM. Des RGR de la cohorte qui avaient reçu un rein provenant d'un DCÉ, 33 % ont reçu un organe qui avait été placé sous PHM et 35 % avaient reçu un rein non perfusé à froid (p = 0,77). L'analyse univariée a également révélé une association entre l'utilisation de la PHM et l'origine ethnique du RGR (non caucasien), une DmIF prolongée, l'administration de basiliximab/alemtuzumab, l'année de la greffe et le centre de transplantation. L'utilisation de la PHM variait grandement d'un centre à un autre, allant de 15 % à 82 %. Dans l'analyse multivariée, l'utilisation de la PHM a été associée à une DmIF prolongée (rapport de cotes [RC]: 1,15; [IC95 %]: 1,07-1,25), au centre de transplantation ainsi qu'aux transplantations réalisées après 2013. Limites: Étude tenue dans une seule unité spécialisée en don d'organes et portant uniquement sur des DND. Absence de données précises sur l'expérience des chirurgiens et sur les raisons personnelles ou logistiques justifiant l'utilisation ou non de la PHM. Conclusion: Nous avons constaté que l'utilisation de la PHM demeure faible et qu'elle varie fortement d'un centre de transplantation à un autre. L'utilisation de la PHM a été fortement associée au centre de transplantation où exerçaient les chirurgiens, ce qui laisse penser que les préférences personnelles et la formation du chirurgien sont des facteurs déterminants pour son utilisation. La disponibilité de la PHM au moment du prélèvement des organes peut également être limitée par des questions logistiques telles que la difficulté de retourner l'appareil. D'autres études se penchant sur les raisons sous-jacentes aux obstacles empêchant l'utilisation de la PHM pourraient aider à en accroître l'utilisation et à améliorer les résultats de la transplantation.

Tri-modal microscope for head and neck tissue identification.

A novel tri-modal microscope combining optical coherence tomography (OCT), spectrally encoded confocal microscopy (SECM) and fluorescence imaging is presented. This system aims at providing a tool for rapid identification of head and neck tissues during thyroid surgery. The development of a dual-wavelength polygon-based swept laser allows for synchronized, co-registered and simultaneous imaging with all three modalities. Further ameliorations towards miniaturization include a custom lens for optimal compromise between orthogonal imaging geometries as well as a double-clad fiber coupler for increased throughput. Image quality and co-registration is demonstrated on freshly excised swine head and neck tissue samples to illustrate the complementarity of the techniques for identifying signature cellular and structural features.