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.

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.

[Management and treatment of chronic inflammatory demyelinating polyradiculoneuropathy: Results of a French national opinion survey]

AIM

To assess the clinical and epidemiological characteristics of chronic inflammatory demyelinating polyneuropathy (CIDP) in a French population opinion survey.

METHODS

A national and multicentric metropolitan French opinion survey was conducted by TNS Healthcare Sofres from October to December 2006. Five thousand and thirty three hospital or private practice physicians were contacted by mail. A specific questionnaire (38 questions) was designed for the survey to evaluate epidemiology, diagnosis and treatment of CIDP.

RESULTS

Four hundred and forty one responses were obtained, 430 were analyzed, 11 being excluded. Only 172 physicians were caring for patients with CIDP, the others feeling that they were not competent for this management (only 34% of the physicians cared for at least one patient during the study). Treatment was managed by only 28% of the physicians and mainly by neurologists working in public hospitals. The percentage of treated patients was 84%, the others were not treated because the impairment was too mild. IVIg were the first intention treatment for 63.2% of the patients and steroids for 30.8% of them. The choice was mainly based on the good tolerance profile of IVIg, both treatments being considered as efficacious.

CONCLUSION

This survey has shown a higher incidence and prevalence of CIDP than expected but a methodological bias may have led to an overestimation (a same patient being included twice). Treatment complied with recommendations and guidelines while the diagnosis may be improved.