Influence of apneic oxygenation on cardiorespiratory system homeostasis

Purpose

The aim of this study was to elucidate the magnitude of variations in oxygenation indices and the pattern of hemodynamic changes in response to the net effect of tracheal apneic oxygenation (AO) with a view to define the safe time limit of its application.

Methods

After obtaining Animal Research Ethics Committee approval, AO was applied in 12 piglets for 40 min. Arterial (a) and mixed venous (v) blood samples for oxygen (O₂) and carbon dioxide (CO₂) tension (PaO₂/PvO₂, PaCO₂/PvCO₂), O₂ saturation (SaO₂/SvO₂), pHa, base excess (BEa), and bicarbonate (HCO₃a) determination and for alveolar O₂ tension (PAO₂), PaO₂/FiO₂ and PaO₂/PAO₂ ratio, arterial–mixed venous O₂ content (AVDO₂), and O₂ extraction ratio (O₂ER) estimation were collected on anesthesia induction, 10, 20, 30, and 40 min during AO and 10 and 20 min after reconnection to the ventilator. Concomitant hemodynamic data were obtained.

Results

Besides PvO₂ and PAO₂, AO adversely influenced PaO₂ (248–113 mmHg), PaCO₂ (35–145 mmHg), PvCO₂, PaO₂/FiO₂, and PaO₂/PAO₂ in a time-depended fashion, whereas SvO₂, AVDO₂, and O₂ER were minimally affected. P(a ? v)CO₂ was reversed throughout AO. Acid–base status derangement, consisting of HCO₃a elevation, BEa widening, and acidemia (pH 6.9) maximized 40 min after AO. During AO, heart rate, systemic and pulmonary circulation pressures, and cardiac output were progressively elevated, whereas systemic vascular resistance was reduced. All the studied parameters reverted almost to baseline within the 20-min period of ventilator reconnection.

Conclusion

Tracheal AO for 40 min ensures acceptable blood oxygenation, promotes notable hypercapnic acidosis, and consequent transient hemodynamic alterations, which are almost completely reversible after reconnection to the ventilator.     

Graft vasculopathy in the skin of a human hand allograft: implications for diagnosis of rejection of vascularized composite allografts

Whereas vascularized composite allografts often undergo acute rejections early in the postgraft period, rejection manifesting with severe vascular changes (graft vasculopathy) has only been observed on three occasions in humans. We report a hand‐allografted patient who developed severe rejection following discontinuation of the immunosuppressive treatment. It manifested clinically with erythematous maculopapules on the skin and pathologically with graft vasculopathy that affected both large vessels and smaller cutaneous ones. The observation that graft vasculopathy can affect skin vessels shows that it is amenable to diagnosis with usual skin biopsy as recommended for the follow‐up of these allografts. Graft vasculopathy developing in the setting of vascularized composite allografts likely represents chronic rejection due to under‐immunosuppression and, if confirmed, should be included in a future update of the Banff classification of vascularized composite allograft rejection.     

An approach for modelling multiple correlated outcomes in a network of interventions using odds ratios

A multivariate meta‐analysis of two or more correlated outcomes is expected to improve precision compared with a series of independent, univariate meta‐analyses especially when there are studies reporting some but not all outcomes. Multivariate meta‐analysis requires estimates of the within‐study correlations, which are seldom available. Existing methods for analysing multiple outcomes simultaneously are limited to pairwise treatment comparisons. We propose a model for a joint, simultaneous synthesis of multiple dichotomous outcomes in a network of interventions and introduce a simple way to elicit expert opinion for the within‐study correlations by utilizing a set of conditional probability parameters. We implement our multiple‐outcomes network meta‐analysis model within a Bayesian framework, which allows incorporation of expert information. As an example, we analyse two correlated dichotomous outcomes, response to the treatment and dropout rate, in a network of pharmacological interventions for acute mania. The produced estimates have narrower confidence intervals compared with the simple network meta‐analysis. We conclude that the proposed model and the suggested prior elicitation method for correlations constitute a useful framework for performing network meta‐analysis for multiple outcomes. Copyright © 2014 John Wiley & Sons, Ltd.     

Cardiopulmonary exercise testing in chronic obstructive pulmonary disease: An update on its clinical value and applications

Chronic obstructive pulmonary disease is a debilitating disorder, characterized by airflow limitation, exercise impairment, reduced functional capacity and significant systemic comorbidity, which complicates the course of the disease. The critical inspiratory constraint to tidal volume expansion during exercise (that may be further complicated by the presence of dynamic hyperinflation), abnormalities in oxygen transportation and gas exchange abnormalities are the major pathophysiological mechanisms of exercise intolerance in COPD patients, and thus, exercise testing has been traditionally used for the functional evaluation of these patients. Compared to various laboratory and field exercise tests, cardiopulmonary exercise testing (CPET) provides a thorough assessment of exercise physiology, involving the integrative respiratory, cardiovascular, muscle and metabolic responses to exercise. This review highlights the clinical utility of CPET in COPD patients, as it provides important information for the determination of the major factors that limit exercise among patients with several comorbidities, allows the assessment of the severity of dynamic hyperinflation, provides valuable prognostic information and can be used to evaluate the response to several therapeutic interventions.     

Comparison of the Seventh and Eighth Edition of American Joint Committee on Cancer (AJCC) Staging for Selected and Nonselected Oropharyngeal Squamous Cell Carcinomas

ObjectivesThe eighth edition American Joint Committee on Cancer (AJCC) Staging incorporates significant changes to the seventh edition in the staging of oropharyngeal squamous cell carcinomas (OPSCC). An important change was the inclusion of OPSCC associated with the human papilloma virus (HPV). Our goal is to compare the performance of both staging systems for patients with HPV-selected and unselected clinical characteristics for OPSCC.MethodsUsing the Surveillance, Epidemiology, and End Results (SEER) database, 2004-2016, we identified patients with likely HPV-associated OPSCC based on surrogate markers (white males aged <65 years old with squamous cell carcinomas of the tonsil and base of tongue), excluding those who underwent surgery. We re-classified these patients using seventh and eighth edition staging for HPV-selected OPSCC and compared the prediction performance of both staging editions for overall survival (OS) and disease-specific survival (DSS). We performed the same analysis for clinically unselected patients with OPSCC.ResultsOur analysis included 9554 patients with a median follow-up of 67 months. Comparing the eighth versus seventh edition for our HPV-selected cohort, clinical staging changed for 92.3% of patients and 10-year OS was 62.2%, 61.2%, 35.3%, and 15.5% for Stage I, II, III, and IV, versus 52.9%, 59.2%, 61.6%, 55.1%, 38.3%, and 15.5% for stage I, II, III, IVA, IVB, and IVC, respectively. A similar pattern was observed for 10-year DSS. The concordance statistics for our HPV-selected cohort were improved for both AJCC 7 (0.6260) and AJCC 8 (0.6846) compared with the unselected cohort, 0.5860 and 0.6457 for AJCC 7 and 8, respectively.ConclusionThe overall performance of discrimination improved from AJCC 7 to AJCC 8 for both clinically selected and unselected patients, but more notably for our HPV-selected cohort. Despite the lack of statistically significant differentiation between Stages I and II in AJCC 8 in either groups, markedly improved discrimination was observed between Stages I/II, III, and IV in the HPV-selected cohort.     

A systematic review of the effectiveness of negative pressure wound therapy in the management of diabetes foot ulcers

Foot ulcers are a common complication in patients with diabetes. Negative pressure wound therapy (NPWT) is a wound care therapy that is being increasingly used in the management of foot ulcers. This article presents a systematic review examining the effectiveness of this therapy. The review question is how effective is NPWT in achieving wound healing in diabetes foot ulcers? The primary outcome for this study was the number of patients achieving complete wound healing (secondary outcomes, other markers of wound healing, adverse events and patient satisfaction). A systematic literature review and tabulative synthesis of randomised controlled trials (RCTs). The review identified four RCTs of weak to moderate quality. Only one study examining NPWT in postamputation wound healing reported data on the primary outcome. These data show a 20% improvement in wound healing [odds ratios = 2·0%, confidence interval (CI) ?1·0 to 4·0] and number needed to treat = 6 (CI 4–64). No serious treatment‐related complications were reported by any of the studies. One study suggested a reduction in the risk of secondary amputation (absolute risk reduction = 7·9%, CI 0·5–15·43). Studies also reported an increase in granulation and wound‐healing rates in patients treated with NPWT therapy. No data on patient satisfaction or experience were reported. While all the studies included in the review indicated that the NPWT therapy is more effective than conventional dressings, the quality of the studies were weak and the nature of the inquiries in terms of outcome and patient selection divergent. There is a strong need for larger trials to assess NPWT therapy in diabetes care with different groups of patients and in relation to different clinical objectives and parameters.     

Total versus selective hepatic vascular exclusion in major liver resections

BACKGROUND: Total hepatic vascular exclusion (THVE) and selective hepatic vascular exclusion (SHVE) are two effective techniques for bleeding control in major hepatic resections. Outcomes of the two procedures were compared. METHODS: Patients undergoing major liver resection were randomly allocated to the THVE and SHVE groups. Intraoperative hemodynamic changes and the postoperative course of the two groups were compared. RESULTS: During vascular clamping, the THVE group showed a significant elevation in pulmonary vascular resistance, systemic vascular resistance, intrapulmonary shunts, and a significant reduction in cardiac index, compared with the SHVE group (P <0.05). Patients undergoing THVE received more crystalloids and blood, showed more severe liver, renal and pancreatic dysfunction, and had a longer hospital stay than the SHVE group (P <0.05). CONCLUSIONS: Both techniques are equally effective in bleeding control in major liver resections. THVE is associated with cardiorespiratory and hemodynamic alterations and may be not tolerated by some patients. SHVE is well tolerated with fewer postoperative complications and shorter hospitalization time.