Anal Intraepithelial Neoplasia Screening With Anal Pap Tests: Follow-up and Corresponding Histology.

BACKGROUND: Anal cytology is used as a screening tool in the detection of precancerous anal squamous lesions. Follow-up clinical examination after abnormal anal cytology is recommended. The objective of this study was to determine how often abnormal cytology was followed by a clinical examination at our institution and how often cytology predicted histologic outcome. MATERIALS AND METHODS: A retrospective chart review was performed (2008-2018) on patients with anal cytology, demonstrating either low-grade or high-grade squamous intraepithelial lesion. Clinical examination within 1 y (digital rectal examination, anoscopy, or high-resolution anoscopy) was recorded. The probability of anal intraepithelial neoplasm on biopsy after dysplasia on cytology was calculated, and McNemar's test was used to determine if there was correspondence between cytology and histology. RESULTS: A total of 327 anal cytology results demonstrated dysplasia (75% low grade and 25% high grade) in 182 patients. Seventy-five percent of dysplastic anal cytology were followed by clinical examination within 1 y, and 50% were biopsied. The probability of dysplasia on histology after dysplasia on cytology was 72% (95% confidence interval: 64%-78.5%). Twenty-eight percent of low-grade cytology results were upgraded to advanced disease (high-grade or invasive cancer) on histology. A low-grade cytology result was unable to preclude high-grade histology in our population. CONCLUSIONS: There is room for improvement at our institution to consistently follow-up with clinical examination after abnormal anal cytology. Our data suggest this is especially important considering anal cytology is an imperfect predictor of histologic anal intraepithelial neoplasia and invasive disease. Clinical examination is a critical component of anal dysplasia screening and follow-up.

Does Anastomotic Leak Contribute to High Failure-to-rescue Rates?

OBJECTIVE: Our aim was to evaluate failure-to-rescue (FTR) after anastomotic leak (AL) in colectomy patients. BACKGROUND: In the era of pay for performance, it is imperative that we understand the quality measures under which we are scrutinized. FTR has been proposed as a marker of surgical quality. We investigated the role of complications in FTR rates in colectomy patients. METHODS: Patients who underwent nonemergent colectomy from 2012 to 2013 were identified from the The American College of Surgeons National Quality Improvement Program (ACS NSQIP database). Mortality after AL was assessed and stratified in relation to mortality after other postoperative complications. χ and logistic regression analysis were used to assess the effect of AL on mortality. RESULTS: We identified 30,101 patients who met inclusion criteria, 1127 suffered an AL (3.7%). FTR was increased in patients with AL compared with those without AL (6% vs 1%, P < 0.001). The mortality rate after leak was similar to mortality after other major complications. Independent risk factors for death after AL included older age (odds ratio [OR] 3.140; 95% confidence interval [CI], 1.744-5.651), cancer diagnosis (OR 2.032; 95% CI, 1.177-3.507), and open approach (OR 2.124; 95% CI, 1.194-3.776) while preoperative bowel preparation was protective (OR 0.563; 95% CI, 0.328-0.969). CONCLUSIONS: AL is a common complication after colectomy with a relatively high FTR rate. As hospitals are penalized for not reaching specific rates of FTR, we must better understand these complex relationships to improve quality and safety of patient care.

Short-term outcomes of minimally invasive versus open colectomy for colon cancer.

BACKGROUND: Laparoscopic and open approaches to colon resection have equivalent long-term outcomes and oncologic integrity for the treatment of colon cancer. Differences in short-term outcomes should therefore help to guide surgeons in their choice of operation. We hypothesized that minimally invasive colectomy is associated with superior short-term outcomes compared to traditional open colectomy in the setting of colon cancer. MATERIALS AND METHODS: Patients undergoing nonemergent colectomy for colon cancer in 2012 and 2013 were selected from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) targeted colectomy participant use file. Patients were divided into two cohorts based on operative approach-open versus minimally invasive surgery (MIS). Univariate, multivariate, and propensity-adjusted multivariate analyses were performed to compare postoperative outcomes between the two groups. RESULTS: A total of 11,031 patients were identified for inclusion in the study, with an overall MIS rate of 65.3% (n = 7200). On both univariate and multivariate analysis, MIS approach was associated with fewer postoperative complications and lower mortality. In the risk-adjusted multivariate analysis, MIS approach was associated with an odds ratio of 0.598 for any postoperative morbidity compared to open (P < 0.001). CONCLUSIONS: This retrospective study of patients undergoing colectomy for colon cancer demonstrates significantly improved outcomes associated with a MIS approach, even when controlling for baseline differences in illness severity. When feasible, minimally invasive colectomy should be considered gold standard for the surgical treatment of colon cancer.

Postoperative complications in patients with rectal cancer are associated with delays in chemotherapy that lead to worse disease-free and overall survival.

OBJECTIVE: The objective of this study was to identify the risk factors for delays in chemotherapy after rectal cancer surgery and evaluate the effects of delayed therapy on long-term outcomes. We also sought to clarify what time frame should be used to define delayed adjuvant chemotherapy. BACKGROUND: Postoperative complications have been found to influence the timing of chemotherapy in patients with colon cancer. Delays in chemotherapy have been shown to be associated with worse overall and disease-free survival in patients with colorectal cancer, although the timing of delay has not been agreed upon in the literature. STUDY DESIGN: We performed a retrospective review of a prospectively maintained rectal cancer database. Univariate analysis was used to identify risk factors for delayed chemotherapy. Kaplan-Meier curves were generated to compare overall and disease-free survival in patients based on complications and timing of chemotherapy. SETTINGS: This study was performed at the University of Wisconsin Hospital, Madison, Wisconsin, between 1995 and 2012. PATIENTS: Patients with rectal cancer who underwent proctectomy with curative intent were included in this study. OUTCOME MEASURES: Timing of chemotherapy, 30-day complications, and 30-day readmissions were the main outcome measures. RESULTS: Postoperative complications and 30-day readmissions were associated with delays in chemotherapy ≥8 weeks after surgery. Patients who received chemotherapy ≥8 weeks postoperatively were found to have worse local and distant recurrence rates and worse overall survival in comparison with patients who received chemotherapy within 8 weeks of surgery. LIMITATIONS: The limitations of this study include its retrospective nature and that it was performed at a single institution. CONCLUSIONS: We found complications and readmissions to be risk factors for delayed chemotherapy. Patients who received therapy ≥8 weeks postoperatively had worse disease-free and overall survival.

Visceral obesity is associated with outcomes of total mesorectal excision for rectal adenocarcinoma.

BACKGROUND AND OBJECTIVES: General obesity, measured by the body mass index (BMI), increases the technical difficulty of total mesorectal excision (TME) but does not affect oncologic outcomes. The purpose of this study is to compare visceral and general obesity as predictors of outcomes of TME for rectal adenocarcinoma. METHODS: Adult patients undergoing TME for rectal adenocarcinoma were retrospectively identified. Preoperative computed tomography scans were used to measure abdominal circumference (AC), visceral (VFA), and subcutaneous fat area (SFA). BMI, AC, VFA, SFA, total fat area (TFA, sum of VFA and SFA), and VFA/SFA ratio were examined for association with operative, postoperative, oncologic, and survival outcomes in a univariate analysis model. RESULTS: Between 1999 and 2009, 113 patients met inclusion criteria. Increasing VFA and VFA/SFA ratio were associated with reduced lymph node retrieval (P = 0.03 and P = 0.009, respectively). The association between increasing VFA/SFA ratio with delayed resumption of oral intake (P = 0.05) and prolonged overall survival (P = 0.003) were also significant. Increasing BMI was associated with improved overall (P = 0.02) but not disease-free survival (P = 0.14). CONCLUSION: Visceral obesity, measured by VFA/SFA ratio, is a better predictor of postoperative, oncologic, and survival outcomes after TME for rectal adenocarcinoma than general obesity measured by the BMI.

Comparable postoperative morbidity and mortality after laparoscopic and open emergent restorative colectomy: outcomes from the ACS NSQIP.

BACKGROUND: Laparoscopic surgery is safe and effective in the management of common abdominal emergencies. However, there is currently a lack of data about its use for emergency colorectal surgery. We hypothesized that laparoscopy can improve the postoperative outcomes of emergency restorative colon resection. METHODS: Adult patients undergoing emergent open and laparoscopic colon resection with primary anastomosis were retrieved from the American College of Surgeons National Surgical Quality Improvement Program database for the years 2005 to 2008 inclusive. Demographic and operative characteristics, laboratory values, and postoperative outcomes were compared between patients undergoing laparoscopic and open colon resection using univariate analyses, multivariate logistic regression, and propensity score analyses. RESULTS: A total of 341 laparoscopic (9.6 %) and 3211 (90.4 %) open colon resections were included. Patients undergoing laparoscopic surgery had a significantly lower prevalence of co-morbidities and better postoperative outcomes. On multivariate analysis, laparoscopic surgery was an independent predictor of a longer operating time (p < 0.001) and shorter total (p = 0.013) and postoperative (p = 0.004) hospital stays, but it did not affect the need for intraoperative blood transfusion (p = 0.488), the 30-day reoperation rates (p = 0.969), or mortality (p = 0.417). After adjusted propensity score analysis, postoperative morbidity (p = 0.833) and mortality (p = 0.568) were comparable in patients undergoing laparoscopic and open surgery. CONCLUSIONS: On a national scale, laparoscopic emergent colon resections are being performed in a small number of patients, who have favorable co-morbidity characteristics and improved postoperative outcomes. Laparoscopic emergent colon resection with primary anastomosis has postoperative morbidity and mortality rates comparable to those seen with the open approach, and it reduces the total and postoperative length of hospital stay.

The Optimal Ileal Pouch: Physiologic Parameters Significantly Correlate with Overall Pouch Function.

BACKGROUND: Ileal pouch function is affected by several patient factors and pouch physiology. The significance of pouch physiology on optimal pouch function has not been well characterized. The purpose of this study was to examine specific post-ileal pouch anal anastomosis (IPAA) physiologic parameters to determine impact on pouch function and quality of life. METHODS: Patients undergoing proctocolectomy with IPAA for ulcerative colitis were examined. Post-IPAA compliance, pouch anal pressure gradient (PAPG), and function were assessed 6-8 months postoperatively. Compliance was calculated as change in volume divided by change in pressure. PAPG was calculated as the difference between anal pressure and intra-pouch pressure at a fixed volume. Pouch function evaluation included stool frequency and episodes of incontinence. Quality of life was evaluated using the Rockwood Fecal Incontinence Quality of Life Scale. RESULTS: A total of 125 patients were investigated. Post-IPAA resting anal pressure averaged 58.1 ± 15 mmHg. Mean volume and intra-pouch pressure at evacuation were 245 mL and 33.9 mmHg, respectively. Compliance averaged 11.2 mmHg/mL with a mean PAPG of - 29.3 mmHg. Compliance and PAPG correlated with 24-h (p = 0.003, p = 0.004) and nighttime stool frequency (p = 0.04, p = 0.03). Daytime continence was impacted by compliance (p = 0.04), PAPG (p = 0.02), and resting anal pressure (p = 0.02). CONCLUSION: This unique evaluation reveals a significant correlation between IPAA physiologic properties and function. Optimal function and quality of life depend in part on maintaining optimal pouch compliance and pressure differentials between the pouch and anal canal, defined by the pouch anal pressure gradient.

Bleeding stomal varices: case series and systematic review of the literature.

BACKGROUND & AIMS: Bleeding stomal varices are a common problem in patients with surgical stomas and portal hypertension, and remain difficult to diagnose and manage. METHODS: We identified all patients at our institution with bleeding stomal varices from 1989 to 2004. We surveyed all patients undergoing ileal pouch-anal anastomosis from 1997 to 2007 for bleeding anastomotic varices. Finally, we performed a systematic review of the literature focusing on diagnosis and treatment of bleeding stomal varices that included 74 English language studies of 234 patients. RESULTS: We identified 8 patients with bleeding stomal varices. Recognition of stomal varices typically was delayed, particularly when failing to examine the ostomy without the appliance. Stomal variceal bleeding was confirmed by Doppler ultrasound or angiographic imaging. Simple local therapy usually stopped bleeding, albeit temporarily. Sclerotherapy was effective, but at the expense of unacceptable stomal damage. Decompressive therapy was required for secondary prophylaxis, including transjugular intravascular transhepatic shunts (2 patients), surgical portosystemic shunts (2 patients), and liver transplantation (1 patient). No patient with an ileal pouch-anal anastomosis developed anastomotic bleeding from varices. CONCLUSIONS: Primary prevention of bleeding stomal varices requires avoidance of creating enterocutaneous stomas in patients with portal hypertension. Careful inspection of the uncovered ostomy is essential for bleeding stomal varices diagnosis. Once identified, conservative measures will stop bleeding temporarily with definitive therapy required, including transjugular intravascular transhepatic shunts, surgical shunts, or liver transplantation.

Bacteremic sepsis disturbs alveolar perfusion distribution in the lungs of rats.

OBJECTIVE: Sepsis often leads to lung injury, although the mechanisms that initiate this are unclear. One preinjury phenomenon that has not been explored previously is the effect of bacterial (nonlipopolysaccharide) sepsis on the distribution of alveolar perfusion. The goals of our studies were to measure this. DESIGN: Randomized, controlled, prospective animal study. SETTING: University animal laboratory. SUBJECTS: Male Sprague-Dawley rats (450-550 g). INTERVENTIONS: We induced sepsis by placing gelatin capsules containing Escherichia coli and Bacteroides fragilis into the abdomens of rats (n = 9). Empty capsules (n = 6) were placed into the abdomens of controls. After 24 hrs, 4-microm-diameter fluorescent latex particles (2 x 10(8)) were infused into the pulmonary circulation. Sepsis was induced in additional rats and controls to assess lung injury, as follows: Lung histology was performed on eight septic rats and on seven controls; lung lavage was performed on three septic rats and three controls after their plasma albumin had been labeled with Evans blue dye. MEASUREMENTS AND MAIN RESULTS: Confocal microscopy was used to prepare digital maps of latex particle trapping patterns (eight per lung). Analysis of these patterns revealed statistically more clustering (perfusion inhomogeneity) down to tissue volumes less than that of ten alveoli in septic lungs compared with controls (p < or = .05). Bacterial counts and neutrophil counts were significantly higher in the circulation of septic rats (p < or = .05). Blood pressures and arterial PO2s were unchanged. Cell counts in histological images were three-fold higher in septic lungs than in controls (p < or = .05). Lung lavage revealed 0.41 +/- 0.03 mL of plasma in the lungs of septic rats, and 0.06 +/- 0.05 mL in the lungs of controls (p < or = .05). CONCLUSIONS: Bacterial sepsis caused significant maldistribution of interalveolar perfusion in the lungs of rats in the absence of significant lung injury.

Hemorrhage progressively disturbs interalveolar perfusion in the lungs of rats.

Acute hemorrhage is often followed by devastating lung injury. However, why blood loss should lead to lung injury is not known. One possibility is that hemorrhage rapidly disturbs the distribution of microvascular perfusion at the alveolar level, which may be a triggering event for subsequent injury. We showed previously that a 30% blood loss in rats caused significant maldistribution of interalveolar perfusion within 45 min (J Trauma 60:158, 2006). In this report, we describe results of further exploration of this phenomenon. We wanted to know if perfusion distribution was disturbed at 15 min, when vascular pressures were significantly reduced by the blood loss, compared with those at 45 min, when the pressures had returned substantially toward normal. We hemorrhaged rats by removing 30% of their blood volume. We quantified interalveolar perfusion distribution by statistically analyzing the trapping patterns of 4-microm-diameter fluorescent latex particles infused into the pulmonary circulation 15 (red particles) and 45 min (green particles) after blood removal. We used confocal fluorescence microscopy to digitally image the trapping patterns in sections of the air-dried lungs and used pattern analysis to quantify the patterns in tissue image volumes that ranged from 1,300 alveoli to less than 1 alveolus. LogDI, a measure of perfusion maldistribution, increased from 1.00 +/- 0.15 at 15 min after blood loss to 1.62 +/- 0.24 at 45 min (P < 0.001). These values were 0.86 +/- 0.22 (15 min) and 1.12 +/- 0.24 (45 min) in control rats (P = 0.03). Hemorrhage caused the green (45 min)-to-red (15 min) particle distance to decrease from 35.9 +/- 6.5 to 28.0 +/- 5.1 microm (P = 0.024) and the red-to-green particle distance to remain unchanged (30.2 +/- 5.7 microm [red]; 31.5 +/- 10.0 microm [green] [n.s.]). We conclude that hemorrhage caused a progressive increase in interalveolar perfusion maldistribution over 45 min that did not correspond to reduced arterial pressures or altered blood gases. Our particle distance measurements led us to further conclude that this maldistribution occurred in areas that were perfused at 15 min rather than in previously unperfused areas .

Laparoscopic restorative proctocolectomy with ileal S-pouch.

PURPOSE: Restorative proctocolectomy has revolutionized the surgical management of ulcerative colitis and familial polyposis syndromes. Though now evolved to include laparoscopy, this approach has not included alternative pouch designs such as ileal S-pouch reconstruction. This comparative analysis evaluated the combination of laparoscopic-assisted total proctocolectomy with an ileal S-pouch design. METHODS: One hundred fifty-six (65 laparoscopic-assisted) total proctocolectomy and ileal S-pouch-anal anastomosis procedures performed between 2003 to 2007 were identified from a prospective surgical database. Operative time, length of incision, length of hospital stay, complications, and return of bowel function were examined. A cost analysis including preoperative through postoperative hospital stay and operating room and postanesthesia care unit costs was performed. RESULTS: The laparoscopic-assisted total proctocolectomy and ileal S-pouch-anal anastomosis procedures were performed for ulcerative colitis in 60 cases and familial adenomatous polyposis in the remaining 5 patients. Four conversions to open technique occurred (6 percent). Comparing laparoscopic and open procedures, the laparoscopic approach took longer to perform than the open technique (mean 451 minutes vs. 347 minutes open; P < 0.001). The mean hospital stay was 6.3 days in the laparoscopic group vs. 8.2 days in the open group (P < 0.001). A detailed cost analysis revealed similar overall costs between the laparoscopic ($18,700) and open approaches ($18,500). CONCLUSION: Use of a laparoscopic total proctocolectomy with ileal S-pouch-anal anastomosis reconstruction minimizes incision size and shortens hospital stay. At a teaching academic institution, the laparoscopic approach requires longer operative times yet a negligible cost disadvantage.

Acute hypoxia does not alter inter-alveolar perfusion distribution in unanesthetized rats.

Effects of hypoxic vasoconstriction on inter-alveolar perfusion distribution (< or =1000 alveoli) have not been studied. To address this, we measured inter-alveolar perfusion distribution in the lungs of unanesthetized rats breathing 10% O(2). Perfusion distributions were measured by analyzing the trapping patterns of 4 microm diameter fluorescent latex particles infused into the pulmonary circulation. The trapping patterns were statistically quantified in confocal images of the dried lungs. Trapping patterns were measured in lung volumes that ranged between less than 1 and 1300 alveoli, and were expressed as the log of the dispersion index (logDI). A uniform (statistically random) perfusion distribution corresponds to a logDI value of zero. The more this value exceeds zero, the more the distribution is clustered (non-random). At the largest tissue volume (1300 alveoli) logDI reached a maximum value of 0.68+/-0.42 (mean+/-s.d.) in hypoxic rats (n = 6), 0.50+/-0.38 in hypercapnic rats (n.s.) and 0.48+/-0.25 in air-breathing controls (n.s.). Our results suggest that acute hypoxia did not cause significant changes in inter-alveolar perfusion distribution in unanesthetized, spontaneously breathing rats.

Clinically Competent and Fiscally at Risk: Impact of Debt and Financial Parameters on the Surgical Resident.

BACKGROUND: While the costs of medical training continue to increase, surgeon income and personal financial decisions may be challenged to manage this expanding debt burden. We sought to characterize the financial liability, assets, income, and debt of surgical residents, and evaluate the necessity for additional financial training. STUDY DESIGN: All surgical trainees at a single academic center completed a detailed survey. Questions focused on issues related to debt, equity, cash flow, financial education, and fiscal parameters. Responses were used to calculate debt-to-asset and debt-to-income ratios. Predictors of moderate risk debt-to-asset ratio (0.5 to 0.9), high risk debt-to-asset ratio (≥0.9), and high risk debt-to-income ratio (>0.4) were evaluated. All analyses were performed in SPSS v.21. RESULTS: One hundred five trainees completed the survey (80% response rate), with 38% of respondents reporting greater than $200,000 in educational debt. Overall, 82% of respondents had a moderate or high risk debt-to-asset ratio. Residency program, year, sex, and perception of financial knowledge did not correlate with high risk debt-to-asset ratio. Residents with high debt-to-asset ratios were more likely to have a high level of concern about debt (52% vs 0%, p < 0.001) when compared with residents who had low debt-to-asset ratios. The majority (79%) of respondents felt strongly that inclusion of additional financial training in residency education is a critical need. CONCLUSIONS: In a climate of increasingly delayed financial gratification, surgical trainees are on critically unstable financial footing. There is a major gap in current surgical education that requires reassessment for the long-term financial health of residents.

Characterizing readmission in ulcerative colitis patients undergoing restorative proctocolectomy.

BACKGROUND: Postoperative readmissions increase costs and affect patient quality of life. Ulcerative colitis (UC) patients are at a high risk for hospital readmission following restorative proctocolectomy (RP). OBJECTIVE: The objective of this study is to characterize UC patients undergoing RP and identify causes and risk factors for readmission. DESIGN: A retrospective review of a prospectively maintained institutional database was performed. Postoperative readmission rates and reasons for readmission were examined following RP. Univariate and multivariate analyses were performed to evaluate for risk factors associated with readmission. RESULTS: Of 533 patients who met our inclusion criteria, 18.2 % (n = 97) were readmitted within 30 days while 22.7 % (n = 121) were readmitted within 90 days of stage I of RP. Younger patient age (OR 1.825, 95 % CI 1.139-2.957), laparoscopic approach (OR 1.943, 95 % CI 1.217-3.104), and increased length of initial stay (OR 1.155, 95 % CI 1.090-1.225) were all associated with 30-day readmission. The most common reason for readmission was dehydration/ileus/partial bowel obstruction, with 10 % of patients readmitted for this reason within 30 days. CONCLUSIONS: Patients undergoing restorative proctocolectomy are at high risk for readmission, particularly following the first stage of the operation. Novel treatment pathways to prevent ileus and dehydration as an outpatient may decrease the rates of readmission following RP.

Postoperative Ileus--More than Just Prolonged Length of Stay?

PURPOSE: Given that postoperative ileus is common in colectomy patients, we sought to examine the association of ileus with adverse events in this patient population. METHODS: The ACS NSQIP puf file from 2012 to 2013 was queried for non-emergent colectomy cases. Predictors of other poor postoperative outcomes in patients who experienced postoperative ileus were assessed using chi-squared and multivariable regression analyses. Chi-squared analysis was used to assess for additive effects of ileus and other postoperative complications on mortality. p Values <0.05 were considered significant. RESULTS: We identified 32,392 patients who underwent non-emergent colectomy. Longer length of stay, higher complication, reoperation, readmission, and mortality rates were identified in patients with ileus (p < 0.001 for all). Overall, 59% of patients with ileus had at least one adverse outcome, compared with 25% of patients without ileus (p < 0.001). Patients who developed ileus in the absence of other complications had an identical mortality rate to patients without ileus (1%). Additional complications led to incremental increases in mortality rates. CONCLUSIONS: Patients with ileus and multiple complications are at significantly increased risk for adverse outcomes. Older patients with more comorbidity were found to be at risk for adverse outcomes in addition to ileus, begging the question of whether these patients may benefit from preoperative optimization.

Perfusion heterogeneity in rat lungs assessed from the distribution of 4-microm-diameter latex particles.

Pulmonary vascular perfusion has been shown to follow a fractal distribution down to a resolution of 0.5 cm(3) (5E11 microm(3)). We wanted to know whether this distribution continued down to tissue volumes equivalent to that of an alveolus (2E5 microm(3)). To investigate this, we used confocal microscopy to analyze the spatial distribution of 4-microm-diameter fluorescent latex particles trapped within rat lung microvessels. Particle distributions were analyzed in tissue volumes that ranged from 1.7E2 to 2.8E8 microm(3). The analysis resulted in fractal plots that consisted of two slopes. The left slope, encompassing tissue volumes less than 7E5 microm(3), had a fractal dimension of 1.50 +/- 0.03 (random distribution). The right slope, encompassing tissue volumes greater than 7E5 microm(3), had a fractal dimension of 1.29 +/- 0.04 (nonrandom distribution). The break point at 7E5 microm(3) corresponds closely to a tissue volume equivalent to that of one alveolus. We conclude that perfusion distribution is random at tissue volumes less than that of an alveolus and nonrandom at tissue volumes greater than that of an alveolus.

Thromboxane receptor analog, U-46619, redistributes pulmonary microvascular perfusion in isolated rat lungs.

Effects of vasoconstriction on the distribution of perfusion among alveoli are not well understood. To address this, we used a new method we developed to determine how microvascular perfusion distribution was affected by a potent vasoconstrictor, the thromboxane receptor analog U-46619. Our method was to infuse 4-microm-diameter fluorescent latex microspheres into the circulation of isolated rat lungs vasoconstricted with U-46619. We used a confocal microscope to image trapping patterns of the particles in dried sections of the lungs and then used dispersion index analysis to quantify the particle patterns in the images, which encompassed approximately 2,000 alveoli. Dispersion indexes revealed significantly more particle clustering (inhomogeneous distribution) in vasoconstricted lungs than in normal flow controls or in controls in which flow was reduced by either lowering pulmonary arterial pressure or raising left atrial pressure. These results suggest that vasoconstriction occurred in the microvessels themselves, which are much smaller vessels than those previously thought to be capable of vasoconstriction.

Predictors of mortality after emergent surgery for acute colonic diverticulitis: analysis of National Surgical Quality Improvement Project data.

BACKGROUND: The surgical treatment of acute colonic diverticulitis is associated with significant morbidity and mortality. However, patient and operative characteristics associated with mortality in this patient population are unclear. We hypothesize that demographic and perioperative variables can be used to predict postoperative mortality.The purpose of this study was to identify perioperative variables predictive of postoperative mortality after emergent surgery for acute diverticulitis. METHODS: Patients with diverticulitis undergoing colostomy and/or partial colectomy with or without primary anastomosis were retrieved from the American College of Surgeons National Surgical Quality Improvement Program database for years 2005 to 2008 inclusive. Only patients undergoing emergent surgery for acute diverticulitis were included. Univariate analyses were performed to compare demographic characteristics, preoperative laboratory values, comorbidities, and intraoperative variables. Variables with a significant (p < 0.10) difference between survivors and nonsurvivors were included in a stepwise logistic regression model to determine predictors of 30-day mortality. Concordance indices (c indices) for postoperative mortality were calculated using 2005 to 2008 data to determine predictive accuracy and validated on 2009 data. RESULTS: A total of 2,214 patients met inclusion criteria. Mean age was 61 years, and 50% of patients were male. Thirty-day mortality was 5.1%. Nine preoperative variables were significantly associated with postoperative mortality on multivariable analysis. The c index of this nine-variable model was 0.901. Renal dysfunction, hypoalbuminemia, American Society of Anesthesiologists class, and age were chosen to create a simpler model, with a c index of 0.886 for 2005 to 2008 data and 0.893 for 2009 data. CONCLUSION: Four readily available perioperative variables can be used to predict 30-day mortality after emergent surgery for acute diverticulitis. LEVEL OF EVIDENCE: Prognostic study, level II.

Bacteremia does not affect cellular uptake of ultrafine particles in the lungs of rats.

To assess the effects of intra-abdominal bacteremia on lung cellular function in vivo, we used electron microscopy to quantify the uptake of 6 nm diameter, albumin-coated colloidal gold particles (overall diam. 20.8 nm) by cells in the lungs of rats made septic by the introduction of live bacteria (E.coli and B. fragilis) into their abdomens. Gold particles were instilled into the trachea 24 hr after bacteremia induction, and lungs were harvested and prepared for electron microscopy 24 hr later. Because bacteremia produces an increase in metabolism, we hypothesized that this might be associated with increased cellular uptake of these particles and also with increased permeability of the alveolar epithelial barrier to them, as bacteremia is also associated with lung injury. We quantified particle uptake by counting particle densities (particles/µm²) within type I and type II epithelial cells, capillary endothelial cells, erythrocytes and neutrophils in the lungs of five septic rats and five sham-sepsis controls. We also counted particle densities within organelles of these cells (nuclei, mitochondria, type II cell lamellar bodies) and within the alveolar interstitium. We found particles to be present within all of these compartments, although we found no differences in particle densities between bacteremic rats and sham-sepsis controls. Our results suggest that these 6 nm particles were able to freely cross cell and organelle membranes, and further suggest that this ability was not altered by bacteremia.