Gender Differences in Self-reported Faculty Developmental Networks.

Scholars have long recognized gender variation in social relationship dynamics. However, how gender shapes developmental networking relationships for career advancement, particularly among university faculty members, is understudied. This area of research is important since women comprise an increasing proportion of faculty and yet report receiving less mentoring and lower career satisfaction, productivity, and advancement than their male counterparts. This cross-sectional study assessed gender differences in self-reported dimensions of faculty participants' developmental networks by collecting information on relationships with developers, who are people who have taken concerted action and offered professional and personal guidance to help participants advance in their careers over the past year. The investigators used egocentric network data from an electronically administered Mentoring Network Questionnaire collected from 159 faculty involved in a mentoring intervention during the pandemic. Faculty were from multiple Southwest and Mountain West institutions. Statistical analyses were performed using the Chi-squared test, Wilcoxon rank-sum test, and unadjusted multilevel regression. Female faculty chose developers of lower gender diversity than male faculty (p=0.01). Compared to male faculty, female faculty reported receiving more psychosocial support from individual developers (p=0.03). Female faculty members' developers were more often characterized as friends and less often described as sponsors and allies than male faculty, based on relative levels of career and psychosocial support that individual developers provided (p<0.001). No gender differences were found in other network characteristics. Female faculty build developmental networks that have different factors compared to male faculty. Greater levels of psychosocial support and fewer allies and sponsors for female faculty may have long-term implications for differential career advancement for women vs. men in academic careers. Strategies to enhance networking should address gender differences and include a structured framework for assessing network gaps.

Mentoring Network Questionnaire Support Scales Reliable and Valid with University Faculty.

The Developmental Network Questionnaire (DNQ) is used in business to self-assess relationships with developers, or people who support one's career. The Mentoring Network Questionnaire (MNQ) is an online modification of the DNQ and includes two scales that rate developer's contributions to career or psychosocial help. The psychometrics of these scales for different populations are unreported. This study analyzed the construct validity and reliability of the two scales measuring support provided by developers of university faculty. Mentors and mentees (G=156) from multiple Southwestern and Mountain West universities rated 741 developers on the MNQ's five-item career- and psychosocial-support scales. Participants responded on a seven-point scale ranging from "never, not at all" to "to the maximum extent possible." Multilevel confirmatory factor analysis (MCFA) using Mplus and the multi-level reliability coefficient omega assessed construct validity and internal consistency reliability, respectively. Results supported the validity of two latent constructs of career- and psychosocial support, each measured by the established five-item scale: Comparative fit index (CFI)=.93, Tucker-Lewis Index (TLI)=.91, root mean square error of approximation (RMSEA)=.06, standardized root mean square residual (SRMR): W=.09, B=.10. The measurement model was improved when the "removes barriers" item was removed from the career-support scale (CFI=.96, TLI=.95, RMSEA=.05, SRMR: W=.06 B=.09. Factor loadings at both the within- and between-levels were strong and statistically significant. Reliability omegas ranged from .85 to .92. Career and psychosocial support provided to university faculty by developers in their networks may be validly and reliably measured at both the within- and between-levels by a modified four-item career support scale and the original five-item psychosocial support scale from the DNQ and the modified MNQ. Limitations include reduced statistical power due to small sample size and lack of testing at the university level. Future work will assess the responsiveness of these scales to measuring change over time in the amount of support provided.

Curriculum-based Faculty Training in Networking: Knowledge and Self-efficacy Outcomes.

Although the advantages of developmental networks are well-known, most faculty do not know how to participate in such networks actively. Additionally, institutions face challenges in teaching faculty the best practices of networking. This deficiency constitutes a critical gap in the literature, which may slow career advancement for faculty, particularly from underrepresented groups. The study's purpose was to examine the effectiveness of a curriculum-based faculty training in developmental networks, utilizing the Extension for Community Health Outcomes (ECHO) platform. In this pre-post study, 33 faculty members participated in the intervention utilizing eight modules involving four competencies. Each module followed a standard format, including a short didactic, two facilitated case study discussions based on real-life scenarios, and self-reading of selected literature. Outcomes included (i) change in knowledge scores obtained from two questions per module and (ii) self-efficacy scores measured on a scale of 0-100. Paired student's t-test and mixed model regression analyses were used. A significant increase in knowledge score was documented using mixed model regression for 4 of the eight modules (mean change score 0.4-0.8, p≤0.03 for all analyses). The proportion of faculty participants reporting correct knowledge items for all modules increased from 49.8% (pre) to 64.3% (post), which was statistically significant (p<0.001). Significant increases in paired self-efficacy scores were reported for each of the eight modules (mean change score 17-37, p<0.05 for all analyses). This study highlights the importance of curriculum-based training in networking. Participants showed a significant increase in pre-post networking self-efficacy and knowledge scores. Our ECHO-based curriculum, facilitator training, and manual enable easy implementation in other institutions, ensuring scalability and adaptability. Our analysis provides the evidence basis for examining the impact of a developmental network intervention in enhancing individual career networks.

Navigating Barriers and Challenges to Achieving Critical Career Milestones Among Faculty Mentees.

For faculty members, job satisfaction, compensation, and career advancement hinge on achieving 'critical' career milestones (e.g., external funding, tenure). Faculty face unique barriers to achieving career milestones (Bagley et al., 2018), and therefore must employ tailored strategies to overcome challenges. The current project extends research on barriers to career milestones (Soller et al., 2022) to examine strategies faculty employ to overcome barriers in the pursuit of critical career milestones. Thirty-seven faculty members participated across eight US academic institutions, including 22 under-represented minorities in science (URM-S; women or racial/ ethnic minorities). Respondents identified critical career milestones they achieved or will pursue within the next 24 months and then discussed strategies used and suggestions for achieving milestones during semi-structured qualitative interviews. The research team conducted a thematic, qualitative, descriptive analysis of qualitative data using NVivo software in a systematic, interactive, team-based process. Four key strategies emerged for navigating barriers in the pursuit of critical career milestones: 1) Careful engagement of mentors and allies; 2) Collaborate and network; 3) Set boundaries and prioritize; and 4) Reflect on values and use personal strengths. Administrators should aim to remove structural barriers, particularly those that reduce equity (Davis et al., 2022). Identifying strategies that faculty employ to overcome challenges can enhance mentoring by helping mentors understand how mentees overcome unique challenges, particularly those that are not easily addressed through structural interventions.

Barriers and Challenges for Career Milestones Among Faculty Mentees.

'Critical' career milestones for faculty (e.g., tenure, securing grant funding) relate to career advancement, job satisfaction, service/leadership, scholarship/research, clinical or teaching activities, professionalism, compensation, and work-life balance. However, barriers and challenges to these milestones encountered by junior faculty have been inadequately studied, particularly those affecting underrepresented minorities in science (URM-S). Additionally, little is known about how barriers and challenges to career milestones have changed during the COVID-19 pandemic for URM-S and non-URM faculty mentees in science. In this study, we conducted semi-structured interviews with 31 faculty mentees from four academic institutions (located in New Mexico, Arizona, Idaho, and Hawaii), including 22 URM-S (women or racial/ethnic). Respondents were given examples of 'critical' career milestones and were asked to identify and discuss barriers and challenges that they have encountered or expect to encounter while working toward achieving these milestones. We performed thematic descriptive analysis using NVivo software in an iterative, team-based process. Our preliminary analysis identified five key themes that illustrate barriers and challenges encountered: Job and career development, Discrimination and a lack of workplace diversity; Lack of interpersonal relationships and inadequate social support at the workplace; Personal and family matters; and Unique COVID-19-related issues. COVID-19 barriers and challenges were related to online curriculum creation and administration, interpersonal relationship development, inadequate training/service/conference opportunities, and disruptions in childcare and schooling. Although COVID-19 helped create new barriers and challenges for junior faculty mentees, traditional barriers and challenges for 'critical' career milestones continue to be reported among our respondents. URM-S respondents also identified discrimination and diversity-related barriers and challenges. Subsequent interviews will focus on 12-month and 24-month follow-ups and provide additional insight into the unique challenges and barriers to 'critical' career milestones that URM and non-URM faculty in science have encountered during the unique historical context of the COVID-19 pandemic.

Developmental Networks Among Mentors and Mentees Involved in a Mentoring Intervention.

The growing application of social network-based theories and methods (Burt et al., 2013) in scholarship on mentoring illustrates that mentoring goes beyond dyadic relationships comprising a senior mentor and a junior protégé (Higgins & Kram, 2001). However, limited data exist on the state of developmental networks of university faculty. This study examines developmental network characteristics among mentors and mentees participating in an ongoing intervention that aims to enhance career success through improved mentoring. Cross-sectional data come from 81 faculty mentors and mentees at three universities in the Southwestern United States. Using the online Modified Mentoring Network Questionnaire (MNQ), participants provided information on relationships with developers, who are people that have taken concerted action, and provided professional and/or personal guidance to help participants advance in their careers. An individual's developmental network comprises relationships with developers. We conducted exploratory analyses examining key characteristics of mentors' and mentees' developmental networks. Participants received psychosocial and career support from an average of 4.9 developers (4.8 and 5.1 for mentors and mentees respectively) from 2.3 arenas (2.2 and 2.4 arenas for mentors and mentees, respectively). While the most common arena was the respondents' current job/position (62%, 64% and 59% for all participants, mentors, and mentees respectively), developers were from graduate school (11%, 6% and 17%); prior jobs/positions (13%, 16% and 9%) and family (8%, 5% and 11%). Our preliminary findings suggest that developers are important for university faculty and that methods and insights from social network analysis can be applied to examine their support networks. As our study is part of an ongoing longitudinal intervention, these findings will inform future analyses that will examine changes in developmental network characteristics and its impact on participants' careers.

Validation of a spectroscopic sensor for the continuous, noninvasive measurement of muscle oxygen saturation and pH.

New patient monitoring technologies can noninvasively and directly provide an assessment of the adequacy of tissue perfusion through the simultaneous determination of muscle oxygen saturation (SmO2) and muscle pH (pHm). Non-pulsatile near infrared spectroscopy is used to determine these microvascular parameters. Two separate studies were conducted using an isolated perfused swine limb preparation to widely vary venous blood oxygen saturation (SviO2) and pH (pHvi) to assess the accuracy of a noninvasive sensor with the capability to simultaneously measure both parameters. The isolated limb model is necessary to establish equilibrium between the venous output of the perfusion circuit and the venule measurement of the spectroscopic sensor. The average absolute difference between SmO2 and SviO2 determined over 50 conditions of SviO2 between 13% and 83% on 3 pig limbs was 3.8% and the coefficient of determination (R(2)) was 0.95. The average absolute difference between pHm and pHvi determined over 69 conditions of pHvi between pHvi 6.9 and pHvi 7.5 on 3 pig limbs was 0.045 pH units with an R(2) of 0.92. Measured accuracy was acceptable to support clinically relevant decision making for the assessment of impaired tissue perfusion and acidosis. Sensors were also evaluated on human subjects. There was no statistical difference in SmO2 by gender or location when multiple sensors were evaluated on the right and left calf, deltoid, and thigh of resting men and women (N = 33). SmO2 precision for subjects at rest was 5.6% over the six locations with four different sensors.

'Smoking': use of cigarettes, cigars and blunts among Southeast Asian American youth and young adults.

Increased use of cigars has been noted among youth, as well as use of blunts (hollowed-out cigars filled with marijuana). Three types of relationships have been previously hypothesized between use of tobacco and marijuana in substance use progression. We aimed to assess these relationships for Southeast Asian American youth and adults in an urban population. We conducted in-person interviews with 164 Southeast Asians, smokers and non-smokers, in two low-income urban communities in Northern California, collecting both quantitative and qualitative data. Analysis of the quantitative data indicated distinct use patterns for blunts, cigars and other forms of marijuana in terms of associations with generation in the United States. The use of these items was also found to be related: ever having smoked cigarettes or blunts increased the risk of ever having smoked the other three items. Qualitative data found indications of all three hypothesized relationships between tobacco and marijuana for youths but not for older adults. For youths in the study, 'smoking' was found to constitute a social construct within which use of cigarettes, cigars and blunts were somewhat interchangeable. Youths in similar settings may initiate into and progress through smoking as an activity domain rather than any one of these items.

Energy transfer at optical frequencies to silicon-based waveguiding structures.

For decades, crystalline silicon (Si) has been the semiconductor of choice for the majority of applications in microelectronics. Recent advances in material science have focused attention on the silicon-on-insulator (SOI) platform, a submicrometer-thick layer of single crystal Si resting on an insulating silicon dioxide (SiO2) layer. Here we calculate the lifetime of an electric dipole moment oscillating in the cover region of several canonical Si waveguiding structures. We show that the vicinity just above SOI produces the most dramatic changes to the radiative lifetime and thus the power spectrum of the emitting dipole. We demonstrate that SOI stands apart from other Si-based optoelectronic platforms in its ability to transport energy, in the form of light, away from an oscillating electric dipole via highly localized, optical- and IR-frequency guided waves.

Application of fiberoptic sensors for the study of hepatic dysoxia in swine hemorrhagic shock.

OBJECTIVES: To determine whether the simultaneous measurement of tissue pH, Pco2, and Po2 with a multiple-parameter fiberoptic sensor can be used to indicate the onset of hepatic dysoxia, to determine critical values, and to assess their use in predicting negative outcomes. DESIGN: Prospective animal study. SETTING: University research laboratory. SUBJECTS: Fourteen Yorkshire swine. INTERVENTIONS: Hemorrhagic shock (n = 11) was induced over 15 mins to lower systolic blood pressure to 40 mm Hg and was maintained for 30, 60, or 90 mins. Resuscitation was achieved with shed blood and warm saline to maintain mean pressure >60 mm Hg for 120 mins. Sham animals (n = 3) were subjected to 90 mins of sham shock, followed by a 120-min recovery period. MEASUREMENTS AND MAIN RESULTS: The multiple-parameter sensor continuously measured tissue pH, Pco2, and Po2. pH and Pco2, indicators of anaerobic metabolism, were plotted against tissue Po2. All shocked animals, but no sham animals, showed a biphasic relationship between Po2 and both pH and Pco2. Curves were fit to both an exponential and a dual-line linear function to determine critical values for Po2, pH, and Pco2. The length of time the animal was dysoxic was evaluated as a predictor of negative outcome. Critical values determined from the exponential models were more sensitive indicators of negative outcome than values determined from the linear model and more sensitive than arterial lactate and tonometric intramucosal pH and Pco2. CONCLUSIONS: The multiple-parameter sensor offers the unique opportunity to study solid as well as hollow organ dysoxia through the simultaneous measurement of interstitial pH, Pco2, and Po2 in a small tissue region. The gradual transition from sufficient oxygen availability to dysoxia as a result of hemorrhage was better described by an exponential equation. The length of time that pH was below or Pco2 was above the critical value determined from the exponential model was predictive of a negative outcome.

Experimental use of an illuminated and magnetic tip, flow-directed pulmonary artery catheter for lung resection.

The authors performed a study to design and evaluate a device giving the surgeon added protection against pulmonary artery injury in a closed thoracic compartment. Eleven swine were used for a total of 12 lobectomies. A light-bearing, magnetic-tipped, modified Swan-Ganz catheter was passed through the jugular vein into the left pulmonary artery. By using magnetic guidance through a port site and balloon inflation, cessation of flow in the pulmonary artery was documented by Doppler. Twelve video-assisted lobectomies were performed. Nine of 12 (75%) lobectomies were completed successfully by using the magnetic-tipped, illuminated balloon catheter. In 4 cases, the catheter displaced because of the short left main pulmonary artery in swine. In one case, the balloon was recovered, and successful lobectomy was performed. The use of a magnetic-tipped, flow-directed device may provide an effective means of endovascular control during thoracoscopic pulmonary arterial dissection.

Simultaneous measurement of hepatic tissue pH, venous oxygen saturation and hemoglobin by near infrared spectroscopy.

The purpose of this study was to investigate the feasibility of using near infrared (NIR) spectroscopy of the liver to simultaneously assess oxygen content in combination with tissue pH, an indicator of anaerobic metabolism. Six anesthetized swine were subjected to 45 min of hemorrhagic shock followed by resuscitation with blood and crystalloid. Calibration models between NIR spectra and reference measurements of tissue pH, hepatic venous oxygen saturation (S(V)O2), and blood hemoglobin concentration (Hb) were developed using partial least-squares regression. Model accuracy was assessed using cross validation. The average correlation (R2) between NIR and reference measurements was 0.87, 0.68, and 0.93, respectively for pH, Hb, and S(V)O2. Estimated accuracy, the root mean squared deviation between spectral, and reference measurements was 0.03 pH units, 0.3 g/dL, and 6%. NIR determination of hepatic oxygen content and tissue pH during shock and resuscitation demonstrated that there can be a variance between hepatic venous oxygenation and regional tissue acidosis. NIR spectroscopy provides a technique to explore the implications of post-shock depression of tissue pH and evaluate new methods of resuscitation.

Energy transfer at optical frequencies to silicon-on-insulator structures.

The refractive-index distribution that is intrinsic to the silicon-on-insulator (SOI) material system makes it possible for optical-frequency guided waves to be confined by the SOI silicon layer. The same refractive-index distribution is unusual among nonmetals in that it is possible for those SOI guided waves to interact strongly with nearby optical-frequency radiators, absorbers, and scatterers (e.g., atoms, molecules, and nanoparticles). We calculate the guided-mode excitation efficiency for an exterior particle near the SOI surface and show that it can attain values greater than 80% under appropriate conditions, thus showing that the SOI waveguide system is an attractive platform for the study of optical-frequency surface interactions.

Directly measured tissue pH is an earlier indicator of splanchnic acidosis than tonometric parameters during hemorrhagic shock in swine.

OBJECTIVE: To compare tissue pH in the stomach, bowel, and abdominal wall muscle during hemorrhagic shock and recovery using tissue electrodes; also, to compare tissue electrode pH measurements to gastric intramucosal pH (pHi), gastric luminal PCO2, and PCO2 gap (gastric luminal CO2--arterial CO2) measured with an air-equilibrated tonometer. DESIGN: Prospective animal study. SETTING: University animal research laboratory. SUBJECTS: Eight anesthetized, mechanically ventilated Yorkshire swine. INTERVENTIONS: Hemorrhagic shock was initiated by withdrawing blood over a 15-min period to lower systolic blood pressure to 45 mm Hg. Shock was maintained for 45 mins and was followed by a 5-min resuscitation to normal blood pressure with a blood/lactated Ringer's (1:2) mixture. Recovery was monitored for 60 mins. MEASUREMENTS AND MAIN RESULTS: pH was measured with electrodes in the submucosa of the stomach, the submucosa of the small bowel, and the abdominal wall muscle. Gastric luminal PCO2 was measured with an air-equilibrated tonometer and pHi and PCO2 gap were calculated. Each organ showed a different sensitivity to shock and resuscitation. The bowel pH responded most rapidly to the onset of hemorrhagic shock and had the largest change in tissue pH. The bowel also showed the most rapid recovery during resuscitation. The submucosal pH of the stomach responded more slowly than the bowel, but faster than the abdominal wall muscle pH, gastric PCO2 gap, or pHi. The smallest changes in organ pH as a result of hemorrhagic shock were seen in the abdominal wall muscle and the stomach as assessed by gastric tonometry. CONCLUSIONS: Direct measurement of tissue pH indicates that intra-abdominal organ pH varies during hemorrhagic shock. The small bowel pH changes the most in magnitude and rapidity compared with stomach pH or abdominal wall muscle pH. Tonometrically derived parameters were not as sensitive in the detection of tissue acidosis during shock and resuscitation as pH measured directly in the submucosa of the stomach or small bowel.

Off-pump versus on-pump coronary artery bypass surgery: a case-matched comparison of clinical outcomes and costs.

BACKGROUND: Results of off-pump coronary artery bypass (OPCAB) surgery have demonstrated trends toward fewer complications, faster recoveries and lower costs compared with on-pump coronary artery bypass (ONCAB) surgery. The validity of such comparisons, however, may be impacted by differences in preoperative risk factors between the two surgeries. METHODS: A total of 76 OPCAB surgery patients were case-matched (by age, sex and Society of Thoracic Surgeons' risk scores) with an equal number of patients who underwent ONCAB surgery by the same surgeon. Postoperative clinical parameters (time on mechanical ventilation, number of blood transfusions, peak cardiac enzyme levels and metabolic acidosis) and outcomes data (intensive care unit and overall in-hospital lengths of stay, perioperative myocardial infarction, atrial fibrillation, stroke, reoperation for bleeding and mortality) were analyzed, and the variable and total costs for each patient were calculated. RESULTS: OPCAB patients required less mechanical ventilation and fewer blood transfusions and had lower peak creatinine phosphokinase levels, as well as a reduced incidence of metabolic acidosis. There were trends toward both shorter intensive care unit and overall in-hospital lengths of stay for OPCAB patients. The average total cost for this group was 20.5% less than for ONCAB patients. There were no differences in rates of atrial fibrillation, myocardial infarction, reoperation for bleeding, stroke or mortality. CONCLUSIONS: By reducing the need for mechanical ventilation, transfusions and intensive care unit and overall in-hospital lengths of stay, OPCAB surgery decreases the use of limited and costly resources without increasing risks. These advantages do not appear to be related to patient selection.

Extracellular cyanobacterial substances inhibit microbial growth.

Cyanobacteria are able to produce extracellular substances with different biological activities and behaviors. The marine cyanobacteria Anabaena sp. strain Hi 26 and Oscillatoria subtilissima strain Bo 62 cause significant color changes in their growth media, while viscosity of the medium is influenced by Rivularia sp. strain Bo 85 and Oscillatoria limnetica strain Flo 1. Sterile-filtered media, pregrown with the organisms mentioned above, were used to study the influence of changes in media bioactivity induced by "excreted substances" on the growth and/or morphological development of five related filamentous cyanobacterial species and on selected heterotrophic microorganisms. Cell lysis, empty sheaths, different lengths of filaments, or even single cells and a decrease in chlorophyll a and protein content were the characteristic changes obtained by such a "cyanobacterial assay." The use of a "precultured" medium, as demonstrated in an "agar diffusion assay," affects in varying degrees the growth of gram-positive and gram-negative heterotrophic bacteria, as well as of the yeast Saccharomyces cerevisiae.

Direct observation of a propagating, planar-waveguide surface mode in a discontinuous film of metal nanoparticles.

We report the observation of p-polarized guided waves that propagate confined to the surface of a two-dimensional array of silver (Ag) nanoparticles of average particle diameter and film thickness of approximately 400 and 154 nm, respectively, and comparable interparticle spacing. We interpret resonant features in the attenuated total reflection angular spectrum as arising from the excitation of guided waves in our discontinuous samples. The excitation of these waves is a direct consequence of the interaction of the light field with the localized resonance of the conduction electrons in the individual metal nanoparticles.

Continuous measurement of gut pH with near-infrared spectroscopy during hemorrhagic shock.

BACKGROUND: The rate and magnitude of pH changes in the bowel during hemorrhagic shock are greater than those in the stomach, implying that gastric intramucosal pH may not be a reliable indicator of gut perfusion. Here, we evaluate near-infrared spectroscopy (NIRS) to assess bowel pH in a swine shock model. METHODS: Laparotomy was performed to place flow probes, pH microelectrodes, and NIRS probes. Shock was maintained for 45 minutes at a blood pressure of 45 mm Hg, and resuscitation was achieved with shed blood and lactated Ringer's solution to baseline over 60 minutes. RESULTS: Hemodynamic measurements were significantly reduced during shock. Lactic acid peaked during resuscitation and remained elevated. NIRS-measured pH was correlated to electrode-measured pH (R2 = 0.903 [ischemia] and R2 = 0.889 [reperfusion]). Estimated measurement accuracy after subject-specific offset correction was 0.083 pH units during ischemia and 0.076 pH units during reperfusion. CONCLUSION: NIRS determination of small-bowel pH may be a good tool to monitor the adequacy of resuscitation.

Thoracoscopic lobectomy with endoarterial vascular control: an experimental study in swine.

BACKGROUND: Video-assisted lobectomy lacks vascular control and presents the potential for serious hemorrhage in a closed cavity. The use of a lighted, flow-directed balloon catheter in the pulmonary artery as an endovascular control device was evaluated. METHODS: A modified light-bearing Swan-Ganz catheter was placed in the left or right pulmonary artery using fluoroscopy. The lit catheter was identified easily through the arterial wall at thoracoscopy. Its inflation allowed the control of proximal blood flow as required. Fully thoracoscopic lobectomy was carried out by isolating and dividing the lobar branches of the pulmonary artery, the pulmonary vein, and the bronchus in anesthetized swine. RESULTS: Forty-two video-assisted anatomic lobectomies were completed in 30 pigs with balloon catheter control of the pulmonary artery. The balloon effectively controlled experimental hemorrhage caused by puncturing arterial branches (n = 4). It allowed the transection of unlooped lobar arteries (n = 42) and the main interlobar pulmonary artery (n = 3). Catheter displacement back to the heart occurred in 5 animals and balloon catheter technical failures occurred in 3. CONCLUSIONS: The lighted, flow-directed balloon catheter was an effective means of avoiding acute hemorrhage and achieving vascular control in a swine lobectomy model.

Diminished myocardial function precedes tissue acidosis during coronary hypoperfusion.

The current study sought to elucidate the relationship between myocardial pH and function during a significant but not absolute reduction in coronary flow. In a canine model, a partial coronary arterial stenosis was created, with the left anterior descending coronary artery (LAD) flow reduced by 50% compared to prestenosis levels, and maintained at that level for the duration of the study. During the experiment, interstitial myocardial pH and regional myocardial function, as assessed by the regional preload recruitable work area (PRWA), were measured. PRWA was depressed to 60% of baseline values, on average, for the entire period of reduced LAD flow. In contrast to the pattern observed with myocardial blood flow and systolic function, metabolic evidence of myocardial ischemia, that is, reduced myocardial pH did not become significantly different from baseline levels until after LAD flow had been reduced for 15 min. Thus, measurable changes in myocardial pH appeared slowly over time despite the fact that regional myocardial blood flow was decreased immediately. Therefore, myocardial pH cannot be used to anticipate alterations in myocardial contractile function.