Interactions between respiration and systemic hemodynamics. Part II: practical implications in critical care.

In Part I of this review, we have covered basic concepts regarding cardiorespiratory interactions. Here, we put this theoretical framework to practical use. We describe mechanisms underlying Kussmaul's sign and pulsus paradoxus. We review the literature on the use of respiratory variations of blood pressure to evaluate volume status. We show the possibilities of attaining the latter aim by investigating with ultrasonography how the geometry of great veins fluctuates with respiration. We provide a Guytonian analysis of the effects of PEEP on cardiac output. We terminate with some remarks on the potential of positive pressure breathing to induce acute cor pulmonale, and on the cardiovascular mechanisms that at times may underly the failure to wean a patient from the ventilator.

Hexyl Aminolevulinate-Guided Fluorescence Cystoscopy in the Diagnosis and Follow-up of Patients with Non-Muscle-invasive Bladder Cancer: A Critical Review of the Current Literature.

CONTEXT: Controversy exists regarding the therapeutic benefit and cost effectiveness of photodynamic diagnosis (PDD) with 5-aminolevulinic acid (5-ALA) or hexyl aminolevulinate (HAL) in addition to white-light cystoscopy (WLC) in the management of non-muscle-invasive bladder cancer (NMIBC). OBJECTIVE: To systematically evaluate evidence regarding the therapeutic benefits and economic considerations of PDD in NMIBC detection and treatment. EVIDENCE ACQUISITION: We performed a critical review of PubMed/Medline, Embase, and the Cochrane Library in October 2012 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Identified reports were reviewed according to the Consolidated Standards of Reporting Trials (CONSORT) and Standards for the Reporting of Diagnostic Accuracy Studies (STARD) criteria. Forty-four publications were selected for inclusion in this analysis. EVIDENCE SYNTHESIS: Included reports used 5-ALA (in 26 studies), HAL (15 studies), or both (three studies) as photosensitising agents. PDD increased the detection of both papillary tumours (by 7-29%) and flat carcinoma in situ (CIS; by 25-30%) and reduced the rate of residual tumours after transurethral resection of bladder tumour (TURBT; by an average of 20%) compared to WLC alone. Superior recurrence-free survival (RFS) rates and prolonged RFS intervals were reported for PDD, compared to WLC in most studies. PDD did not appear to reduce disease progression. Our findings are limited by tumour heterogeneity and a lack of NMIBC risk stratification in many reports or adjustment for intravesical therapy use in most studies. Although cost effectiveness has been demonstrated for 5-ALA, it has not been studied for HAL. CONCLUSIONS: Moderately strong evidence exists that PDD improves tumour detection and reduces residual disease after TURBT compared with WLC. This has been shown to improve RFS but not progression to more advanced disease. Further work to evaluate cost effectiveness of PDD is required.

Estimation of percentage body fat in 6- to 13-year-old children by skinfold thickness, body mass index and waist circumference.

We evaluated the accuracy of skinfold thicknesses, BMI and waist circumference for the prediction of percentage body fat (PBF) in a representative sample of 372 Swiss children aged 6-13 years. PBF was measured using dual-energy X-ray absorptiometry. On the basis of a preliminary bootstrap selection of predictors, seven regression models were evaluated. All models included sex, age and pubertal stage plus one of the following predictors: (1) log-transformed triceps skinfold (logTSF); (2) logTSF and waist circumference; (3) log-transformed sum of triceps and subscapular skinfolds (logSF2); (4) log-transformed sum of triceps, biceps, subscapular and supra-iliac skinfolds (logSF4); (5) BMI; (6) waist circumference; (7) BMI and waist circumference. The adjusted determination coefficient (R² adj) and the root mean squared error (RMSE; kg) were calculated for each model. LogSF4 (R² adj 0.85; RMSE 2.35) and logSF2 (R² adj 0.82; RMSE 2.54) were similarly accurate at predicting PBF and superior to logTSF (R² adj 0.75; RMSE 3.02), logTSF combined with waist circumference (R² adj 0.78; RMSE 2.85), BMI (R² adj 0.62; RMSE 3.73), waist circumference (R² adj 0.58; RMSE 3.89), and BMI combined with waist circumference (R² adj 0.63; RMSE 3.66) (P < 0.001 for all values of R² adj). The finding that logSF4 was only modestly superior to logSF2 and that logTSF was better than BMI and waist circumference at predicting PBF has important implications for paediatric epidemiological studies aimed at disentangling the effect of body fat on health outcomes.

Critical appraisal of single port access cholecystectomy.

BACKGROUND: Single port access (SPA) cholecystectomy is a new concept in laparoscopic surgery. A review of existing results was performed to evaluate critically the current state of SPA with specific reference to feasibility, safety, learning curve, indications and cost-effectiveness. METHODS: All papers identified in MEDLINE until 15 February 2010 and all other relevant papers obtained from cited references were reviewed, without any language restriction. Case reports and series of fewer than three patients were excluded. RESULTS: After selection, 24 studies including 895 patients were analysed. None was randomized. Feasibility seems to be established, with a conversion rate of 2 per cent. SPA was not standardized and there was much technical variation. The learning curve could not be determined. Median follow-up time was 3 (range 0.25-12) months. The overall published complication rate was 5.4 per cent and the biliary complication rate 0.7 per cent. The rate of umbilical complications ranged from 2 to 10 per cent. CONCLUSION: SPA cholecystectomy seems feasible, but standardization, safety and the real benefits for patients need further assessment. Uncontrolled wide adoption of this approach may be responsible for a rise in biliary complications.

The influence of drugs used in cardiac anaesthesia and critical care on multiple electrode aggregometry: an in-vitro volunteer study.

BACKGROUND: Multiple electrode aggregometry (MEA) is a point-of-care test evaluating platelet function and the efficacy of platelet inhibitors. In MEA, electrical impedance of whole blood is measured after addition of a platelet activator. Reduced impedance implies platelet dysfunction or the presence of platelet inhibitors. MEA plays an increasingly important role in the management of perioperative platelet dysfunction. In vitro, midazolam, propofol, lidocaine and magnesium have known antiplatelet effects and these may interfere with MEA interpretation. OBJECTIVE: To evaluate the extent to which MEA is modified in the presence of these drugs. DESIGN: An in-vitro study using blood collected from healthy volunteers. SETTING: Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland, 2010 to 2011. PATIENTS: Twenty healthy volunteers. INTERVENTION: Measurement of baseline MEA was using four activators: arachidonic acid, ADP, TRAP-6 and collagen. The study drugs were then added in three increasing, clinically relevant concentrations. MAIN OUTCOME MEASURE: MEA was compared with baseline for each study drug. RESULTS: Midazolam, propofol and lidocaine showed no effect on MEA at any concentration. Magnesium at 2.5 mmol l had a significant effect on the ADP and TRAP tests (31 ± 13 and 96 ± 39 AU, versus 73 ± 21 and 133 ± 28 AU at baseline, respectively), and a less pronounced effect at 1 mmol l on the ADP test (39 ± 0 AU). CONCLUSION: Midazolam, propofol and lidocaine do not interfere with MEA measurement. In patients treated with high to normal doses of magnesium, MEA results for ADP and TRAP-tests should be interpreted with caution. TRIAL REGISTRATION: Clinicaltrials.gov (no. NCT01454427).

Radial forearm free flap donor site morbidity: ulnar-based transposition flap vs split-thickness skin graft.

OBJECTIVES: To evaluate morbidity associated with the radial forearm free flap donor site and to compare functional and aesthetic outcomes of ulnar-based transposition flap (UBTF) vs split-thickness skin graft (STSG) closure of the donor site.¦DESIGN: Case-control study.¦SETTING: Tertiary care institution.¦PATIENTS: The inclusion criteria were flap size not exceeding 30 cm(2), patient availability for a single follow-up visit, and performance of surgery at least 6 months previously. Forty-four patients were included in the study and were reviewed. Twenty-two patients had UBTF closure, and 22 had STSG closure.¦MAIN OUTCOME MEASURES: Variables analyzed included wrist mobility, Michigan Hand Outcomes Questionnaire scores, pinch and grip strength (using a dynamometer), and hand sensitivity (using monofilament testing over the radial nerve distribution). In analyses of operated arms vs nonoperated arms, variables obtained only for the operated arms included Vancouver Scar Scale scores and visual analog scale scores for Aesthetics and Overall Arm Function.¦RESULTS: The mean (SD) wrist extension was significantly better in the UBTF group (56.0° [10.4°] for nonoperated arms and 62.0° [9.7°] for operated arms) than in the STSG group (59.0° [7.1°] for nonoperated arms and 58.4° [12.1°] for operated arms) (P = .02). The improvement in wrist range of motion for the UBTF group approached statistical significance (P = .07). All other variables (Michigan Hand Outcomes Questionnaire scores, pinch and grip strength, hand sensitivity, and visual analog scale scores) were significantly better for nonoperated arms vs operated arms, but no significant differences were observed between the UBTF and STSG groups.¦CONCLUSIONS: The radial forearm free flap donor site carries significant morbidity. Donor site UBTF closure was associated with improved wrist extension and represents an alternative method of closure for small donor site defects.

States of maximum entropy production in a onedimensional vertical model with convective adjustment

We investigate the hypothesis that the atmosphere is constrained to maximize its entropy production by using a one-dimensional (1-D) vertical model. We prescribe the lapse rate in the convective layer as that of the standard troposphere. The assumption that convection sustains a critical lapse rate was absent in previous studies, which focused on the vertical distribution of climatic variables, since such a convective adjustment reduces the degrees of freedom of the system and may prevent the application of the maximum entropy production (MEP) principle. This is not the case in the radiative–convective model (RCM) developed here, since we accept a discontinuity of temperatures at the surface similar to that adopted in many RCMs. For current conditions, the MEP state gives a difference between the ground temperature and the air temperature at the surface ≈10 K. In comparison, conventional RCMs obtain a discontinuity ≈2 K only. However, the surface boundary layer velocity in the MEP state appears reasonable (≈3 m s-¹). Moreover, although the convective flux at the surface in MEP states is almost uniform in optically thick atmospheres, it reaches a maximum value for an optical thickness similar to current conditions. This additional result may support the maximum convection hypothesis suggested by Paltridge (1978)

Understanding the Many Faces of Child Neglect: A Review of Denial of Critical Care Cases in Iowa, 2005

In recent years, Iowa leaders and the general public have focused on the abuse children have suffered from several causes, including sexual abuse, methamphetamine manufacturing, and serious physical injury. While this public attention and concern is welcome, the harm that children suffer from neglect, which Iowa law calls denial of critical care, has received little attention, despite representing almost three-quarters of all child abuse cases. With financial assistance from the Greater Des Moines Community Foundation in 2003-2004, Prevent Child Abuse Iowa started a Child Neglect Awareness Project, with the goal of creating greater understanding and awareness of child neglect in Iowa.

'Toxic' and 'Nontoxic': confirming critical terminology concepts and context for clear communication

If 'the dose makes the poison', and if the context of an exposure to a hazard shapes the risk as much as the innate character of the hazard itself, then what is 'toxic' and what is 'nontoxic'? This article is intended to help readers and communicators: anticipate that concepts such as 'toxic' and 'nontoxic' may have different meanings to different stakeholders in different contexts of general use, commerce, science, and the law; recognize specific situations in which terms and related information could potentially be misperceived or misinterpreted; evaluate the relevance, reliability, and other attributes of information for a given situation; control actions, assumptions, interpretations, conclusions, and decisions to avoid flaws and achieve a desired outcome; and confirm that the desired outcome has been achieved. To meet those objectives, we provide some examples of differing toxicology terminology concepts and contexts; a comprehensive decision-making framework for understanding and managing risk; along with a communication and education message and audience-planning matrix to support the involvement of all relevant stakeholders; a set of CLEAR-communication assessment criteria for use by both readers and communicators; example flaws in decision-making; a suite of three tools to assign relevance vs reliability, align know vs show, and refine perception vs reality aspects of information; and four steps to foster effective community involvement and support. The framework and supporting process are generally applicable to meeting any objective.