Detect Fluid Early from Intrathoracic Impedance Monitoring (DEFEAT-PE) is a prospective, multicenter study of multiple intrathoracic impedance vectors to detect pulmonary congestion (PC) events. ...Changes in intrathoracic impedance between the right ventricular (RV) coil and device can (RVcoil→Can) of implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy ICDs (CRT-Ds) are used clinically for the detection of PC events, but other impedance vectors and algorithms have not been studied prospectively. An initial 75-patient study was used to derive optimal impedance vectors to detect PC events, with 2 vector combinations selected for prospective analysis in DEFEAT-PE (ICD vectors: RVring→Can + RVcoil→Can, detection threshold 13 days; CRT-D vectors: left ventricular ring→Can + RVcoil→Can, detection threshold 14 days). Impedance changes were considered true positive if detected <30 days before an adjudicated PC event. One hundred sixty-two patients were enrolled (80 with ICDs and 82 with CRT-Ds), all with ≥1 previous PC event. One hundred forty-four patients provided study data, with 214 patient-years of follow-up and 139 PC events. Sensitivity for PC events of the prespecified algorithms was as follows: ICD: sensitivity 32.3%, false-positive rate 1.28 per patient-year; CRT-D: sensitivity 32.4%, false-positive rate 1.66 per patient-year. An alternative algorithm, ultimately approved by the US Food and Drug Administration (RVring→Can + RVcoil→Can, detection threshold 14 days), resulted in (for all patients) sensitivity of 21.6% and a false-positive rate of 0.9 per patient-year. The CRT-D thoracic impedance vector algorithm selected in the derivation study was not superior to the ICD algorithm RVring→Can + RVcoil→Can when studied prospectively. In conclusion, to achieve an acceptably low false-positive rate, the intrathoracic impedance algorithms studied in DEFEAT-PE resulted in low sensitivity for the prediction of heart failure events.
Abstract Background Emotional intelligence (EI) has been associated with improved work performance and job satisfaction in several industries. We evaluated whether EI was associated with higher ...measures of work performance and job satisfaction in surgical residents. Methods We distributed the validated Trait EI Questionnaire and job satisfaction survey to all general surgery residents at a single institution in 2015. EI and job satisfaction scores were compared with resident performance using faculty evaluations of clinical competency–based surgical milestones and standardized test scores including the United States Medical Licensing Examination (USMLE) and American Board of Surgery In-Training Examination (ABSITE). Statistical comparison was made using Pearson correlation and simple linear regression adjusting for postgraduate year level. Results The survey response rate was 68.9% with 31 resident participants. Global EI was associated with scores on USMLE Step 2 ( r = 0.46, P = 0.01) and Step 3 ( r = 0.54, P = 0.01) but not ABSITE percentile scores ( r = 0.06, P = 0.77). None of the 16 surgical milestone scores were significantly associated with global EI or EI factors before or after adjustment for postgraduate level. Global EI was associated with overall job satisfaction ( r = 0.37, P = 0.04). Of the facets of job satisfaction, global EI was significantly associated with views of supervision ( r = 0.42, P = 0.02) and nature of work ( r = 0.41, P = 0.02). Conclusions EI was associated with job satisfaction and USMLE performance but not ACGME competency–based milestones or ABSITE scores. EI may be an important factor for fulfillment in surgical training that is not currently captured with traditional in-training performance measures.
Background With increasing use of thyroid ultrasonography, thyroid nodules have been found to be extremely common. For over 25 years, fine needle aspiration (FNA) has been the pivotal diagnostic test ...to discriminate benign from potentially malignant thyroid nodules. Recently, false negative rates exceeding 10% have led to recommendations that thyroid nodules ≥4 cm should be resected regardless of cytology results. Our aim was to determine the false negative rate of FNA cytology on thyroid nodules ≥3 cm interpreted as benign at our institution. Methods A retrospective review was performed at Mayo Clinic from January 2002 through December 2006. Results From 6,921 ultrasonographic-guided thyroid FNAs, 742 were interpreted as benign and ≥3 cm. A definitive histologic diagnosis was available for 145 (20%) patients who underwent thyroidectomy: 1 (0.7%) was false negative. No additional thyroid malignancies were identified in 550 index nodules with average follow-up of 3 years. Conclusion With precise ultrasonographic-guided aspiration, strict adherence to guidelines for adequacy of the sample, proper cytologic preparation, and most importantly, expert cytologic analysis, a diagnosis of benign is extremely reliable for thyroid nodules, regardless of size. Resection for diagnosis is not necessary, and a size ≥3 cm should not be an independent indication for resection.
Current techniques for characterizing biofilm physiology lack the signal filtering capability required for quantifying signals associated with real time biologically active transport. Though a great ...deal was learned from previous investigations, no results have been reported on the characterization of in vivo, real time biofilm flux using non-invasive (non-destructive) techniques. This article introduces the self-referencing technique for applications in biofilm physiology. Self-referencing is a non-invasive sensing modality which is capable of sensing changes in biologically active analyte flux as small as 10 fmol cm⁻² s⁻¹. Studies directly characterizing flux, as opposed to concentration, have the advantage of quantifying real time changes in biologically active transport which are otherwise lost to background noise. The use of this modality for characterizing biofilm physiology is validated with a reversible enzyme inhibition study. The experiment used self-referencing potentiometric sensors for quantifying real time ammonium and nitrite flux. Amperometric and optical sensing methods, though not presented herein, are also powerful sensing tools which benefit from operation in self-referencing mode. Reversible ammonia monooxygenase inhibition by a copper chelator (thiourea), and subsequent relief by excess copper addition was successfully demonstrated using self-referencing ion-selective microelectrodes for a mature Nitrosomonas europaea biofilm. Biotechnol. Bioeng. 2009; 102: 791-799.
Objectives This study evaluated the effect of the fellowship interview process in a cohort of general surgery residents. We hypothesized that the interview process would be associated with ...significant clinical time lost, monetary expenses, and increased need for shift coverage. Design An online anonymous survey link was sent via e-mail to general surgery program directors in June 2014. Program directors distributed an additional survey link to current residents in their program who had completed the fellowship interview process. Setting United States allopathic general surgery programs. Participants Overall, 50 general surgery program directors; 72 general surgery residents. Results Program directors reported a fellowship application rate of 74.4%. Residents most frequently attended 8 to 12 interviews (35.2%). Most (57.7%) of residents reported missing 7 or more days of clinical training to attend interviews; these shifts were largely covered by other residents. Most residents (62.3%) spent over $4000 on the interview process. Program directors rated fellowship burden as an average of 6.7 on a 1 to 10 scale of disruption, with 10 being a significant disruption. Most of the residents (57.3%) were in favor of change in the interview process. We identified potential areas for improvement including options for coordinated interviews and improved content on program websites. Conclusions The surgical fellowship match is relatively burdensome to residents and programs alike, and merits critical assessment for potential improvement.
Background Previous intraoperative nerve monitoring (IONM) studies have demonstrated modest-to-no benefit and did not include a nationwide sample of hospitals representative of broad thyroidectomy ...practices. This national study was designed to compare vocal cord paralysis (VCP) rates between thyroidectomy with IONM and without monitoring (conventional). Study Design We performed a retrospective analysis of 243,527 thyroidectomies during 2008 to 2011 using the Nationwide Inpatient Sample. Results Use of IONM increased yearly throughout the study period (2.6% 2008, 5.6% 2009, 6.1% 2010, 6.9% 2011) and during this time, VCP rates in the IONM group initially increased year-over-year (0.9% 2008, 2.4% 2009, 2.5% 2010, 1.4% 2011). In unadjusted analyses, IONM was associated with significantly higher VCP rates (conventional 1.4% vs IONM 1.9%, p < 0.001). After propensity score matching, IONM remained associated with higher VCP rates in partial thyroidectomy and lower VCP rates for total thyroidectomy with neck dissection. Hospital-level analysis revealed that VCP rates were not explained by differential laryngoscopy rates, decreasing the likelihood of ascertainment bias. Additionally, for hospitals in which IONM was applied to more than 50% of thyroidectomies, lower VCP rates were observed (1.1%) compared with hospitals that applied IONM to less than 50% (1.6%, p = 0.016). Higher hospital volume correlated with lower VCP rates in both groups (<75, 75 to 299, >300 thyroidectomies/year: IONM, 2.1%, 1.7%, 1.7%; conventional, 1.5%, 1.3%, 1.0%, respectively). Conclusions According to this study, IONM has not been broadly adopted into practice. Overall, IONM was associated with a higher rate of VCP even after correction for numerous confounders. In particular, low institutional use of IONM and use in partial thyroidectomies are associated with higher rates of VCP. Further studies are warranted to support the broader application of IONM in patients where benefit can be reliably achieved.
Glucose is the central molecule in many biochemical pathways, and numerous approaches have been developed for fabricating micro biosensors designed to measure glucose concentration in/near cells ...and/or tissues. An inherent problem for microsensors used in physiological studies is a low signal-to-noise ratio, which is further complicated by concentration drift due to the metabolic activity of cells. A microsensor technique designed to filter extraneous electrical noise and provide direct quantification of active membrane transport is known as self-referencing. Self-referencing involves oscillation of a single microsensor via computer-controlled stepper motors within a stable gradient formed near cells/tissues (i.e., within the concentration boundary layer). The non-invasive technique provides direct measurement of trans-membrane (or trans-tissue) analyte flux. A glucose micro biosensor was fabricated using deposition of nanomaterials (platinum black, multiwalled carbon nanotubes, Nafion) and glucose oxidase on a platinum/iridium microelectrode. The highly sensitive/selective biosensor was used in the self-referencing modality for cell/tissue physiological transport studies. Detailed analysis of signal drift/noise filtering via phase sensitive detection (including a post-measurement analytical technique) are provided. Using this highly sensitive technique, physiological glucose uptake is demonstrated in a wide range of metabolic and pharmacological studies. Use of this technique is demonstrated for cancer cell physiology, bioenergetics, diabetes, and microbial biofilm physiology. This robust and versatile biosensor technique will provide much insight into biological transport in biomedical, environmental, and agricultural research applications.
A classic problem in traditional conductance measurement of left ventricular (LV) volume is the separation of the contributions of myocardium from blood. Measurement of both the magnitude and the ...phase of admittance allow estimation of the time-varying myocardial contribution, which provides a substantial improvement by eliminating the need for hypertonic saline injection. We present in vivo epicardial surface probe measurements of electrical properties in murine myocardium using two different techniques (a digital and an analog approach). These methods exploit the capacitive properties of the myocardium, and both methods yield similar results. The relative permittivity varies from approximately 100 000 at 2 kHz to approximately 5000 at 50 kHz. The electrical conductivity is approximately constant at 0.16 S/m over the same frequency range. These values can be used to estimate and eliminate the time-varying myocardial contribution from the combined signal obtained in LV conductance catheter measurements, thus yielding the blood contribution alone. To study the effects of albumin on the blood conductivity, we also present electrical conductivity estimates of murine blood with and without typical administrations of albumin during the experiment. The blood conductivity is significantly altered (p < 0.0001) by administering albumin (0.941 S/m with albumin, 0.478 S/m without albumin).
The self-referencing electrode technique was employed to noninvasively measure gradients of dissolved oxygen in the medium
immediately surrounding developing mouse embryos and, thereby, characterized ...changes in oxygen consumption and utilization
during development. A gradient of depleted oxygen surrounded each embryo and could be detected >50 μm from the embryo. Blastocysts
depleted the surrounding medium of 0.6 ± 0.1 μM of oxygen, whereas early cleavage stage embryos depleted the medium of only
0.3 ± 0.1 μM of oxygen, suggesting a twofold increase in oxygen consumption at the blastocyst stage. Mitochondrial oxidative
phosphorylation (OXPHOS) accounted for 60â70% of the oxygen consumed by blastocysts, while it accounted for only 30% of the
total oxygen consumed by cleavage-stage embryos. The amount of oxygen consumed by non-OXPHOS mechanisms remained relatively
constant throughout preimplantation development. By contrast, the amount of oxygen consumed by OXPHOS in blastocysts is greater
than that consumed by OXPHOS in cleavage-stage embryos. The amount of oxygen consumed by one-cell embryos was modulated by
the absence of pyruvate from the culture medium. Treatment of one-cell embryos and blastocysts with diamide, an agent known
to induce cell death in embryos, resulted in a decline in oxygen consumption, such that the medium surrounding dying embryos
was not as depleted of oxygen as that surrounding untreated control embryos. Together these results validate the self-referencing
electrode technique for analyzing oxygen consumption and utilization by preimplantation embryos and demonstrate that changes
in oxygen consumption accompany important physiological events, such as development, response to medium metabolites, or cell
death.
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