The impact of tranexamic acid on administration of red blood cell transfusions for resection of colorectal liver metastases.

BACKGROUND: Red blood cell transfusions (RBCT) remain a concern for patients undergoing hepatectomy. The effect of tranexamic acid (TXA), an anti-fibrinolytic, on receipt of RBCT in colorectal liver metastases (CRLM) resection was examined. METHODS: Hepatectomies for CRLM over 2009-2014 were included. Primary outcome was 30-day receipt of RBCT. Secondary outcomes were 30-day major morbidity (Clavien-Dindo III-V) and 90-day mortality. Multivariable modelling examined the adjusted association between TXA and outcomes. RESULTS: Of 433 included patients, 146 (34%) received TXA. TXA patients were more likely to have inflow occlusion (41.8% vs. 23.1%; p < 0.01) and major hepatectomies (56.1% vs. 45.6%; p = 0.0193). TXA was independently associated with lower risk of RBCT (Relative risk (RR) 0.59; 95% confidence interval (95%CI): 0.42-0.85), but not with 30-day major morbidity (adjusted RR 1.02; 95%CI: 0.64-1.60) and 90-day mortality (univariable RR 0.99; 95%CI: 0.95-1.03). CONCLUSION: Intraoperative TXA was associated with a 41% reduction in risk of 30 -day receipt of RBCT after hepatectomy for CRLM. This finding is important to potentially improve healthcare resource allocation and patient outcomes. Pending further evidence, intraoperative TXA may be an effective method of reducing RBCT in hepatectomy for CRLM.

Elevated Lactate is Independently Associated with Adverse Outcomes Following Hepatectomy.

BACKGROUND: Arterial lactate is frequently monitored to indicate tissue hypoxia and direct therapy. We sought to determine whether early post-hepatectomy lactate (PHL) is associated with adverse outcomes and define factors associated with PHL. METHODS: Hepatectomy patients at a single institution from 2003 to 2012 with PHL available were included. Univariable and multivariable analyses examined factors associated with PHL and the relationship between PHL and 30-day major morbidity (Clavien grade III-V), 90-day mortality, and length of stay (LOS). RESULTS: Of 749 hepatectomies, 490 were included of whom 71.4% had elevated PHL (≥2 mmol/L). Cirrhosis (coefficient 0.31, p = 0.039), Charlson comorbidity index (coefficient 0.05, p < 0.001), major resections (coefficient 0.34, p < 0.001), procedure time (coefficient 0.08, p < 0.001), and blood loss (coefficient 0.11, p < 0.001) were associated with PHL. As lactate increased from <2 to ≥6 mmol/L, morbidity rose from 11.6 to 40.6%, and mortality from 0.7 to 22.7%. PHL was independently associated with 90-day mortality (OR 1.52 p < 0.001) and 30-day morbidity (OR 1.19, p = 0.002), but not LOS (rate ratio 1.03, p = 0.071). CONCLUSION: Patients with elevated PHL in the initial postoperative period should be carefully monitored due to increased risk of major morbidity and mortality. Further research on the impact of lactate-directed fluid therapy is warranted.

Is central venous pressure still relevant in the contemporary era of liver resection?

BACKGROUND: Perioperative red blood cell transfusion (RBCT) remains common after liver resection and carries risk of increased morbidity and worse oncologic outcomes. We sought to assess the factors associated with perioperative RBCT after hepatectomy with a focus on intraoperative hemodynamics. METHODS: We performed a retrospective review of our prospective hepatectomy database, supplemented by a review of anesthetic records of all patients undergoing hepatectomy with hemodynamic monitoring (arterial and central venous pressures [CVP]) from 2003-2012. Primary outcome was perioperative RBCT (during and within 30 d after surgery). After descriptive and univariate comparisons, multivariate analysis was conducted to identify factors associated with RBCT. RESULTS: Of 851 hepatectomies, 530 had complete hemodynamic data and 30.2% (161 of 530) received RBCT. Among transfused patients, female gender (P = 0.01), preoperative anemia (P < 0.001), and major liver resection (P = 0.02) were more common. Mean estimated blood loss was 1.1 L higher (2.0 versus 0.9 L; P < 0.001) and operating time was 1.1 h longer (5.8 versus 4.7 h; P < 0.001) in transfused patients. Trends in intraoperative CVP differed significantly based on transfusion status (P = 0.007). Independent factors associated with RBCT included female gender (odds ratio [OR], 2.27; P = 0.01), preoperative anemia (OR, 2.38; P = 0.03), longer operative time (OR, 1.19 per hour; P = 0.03), and higher intraoperative CVP at 1 h during surgery (OR, 1.10 per mm Hg; P = 0.005). CONCLUSIONS: Likelihood of RBCT is independently associated with female gender, preoperative anemia, longer operative time, and higher intraoperative CVP. Focus on management of preoperative anemia, operative efficiency, and low intraoperative CVP is needed to minimize the need for RBCTs.

The Impact of Perioperative Red Blood Cell Transfusions on Long-Term Outcomes after Hepatectomy for Colorectal Liver Metastases.

BACKGROUND: Red blood cell transfusions (RBCTs) are associated with cancer recurrence following resection of colorectal cancer. Their impact after colorectal liver metastases (CRLM) resection remains debated. We sought to explore the association between perioperative RBCT and oncologic outcomes following resection of CRLM. METHODS: We reviewed patients undergoing partial hepatectomy for CRLM from 2003 to 2012 at a single institution. Date of death was abstracted from a validated population-based cancer registry. Primary outcome was overall survival (OS). Secondary outcome was recurrence-free survival (RFS). Survivals were estimated using Kaplan-Meier methods and compared with log-rank test based on transfusion status. Cox regression analysis examined the association of RBCT with OS and RFS, while adjusting for age, preoperative chemotherapy, Clinical Risk Score, and period of treatment (2003-2007 vs. 2008-2012). RESULTS: Among 483 patients, 27.5 % received RBCT. Ninety-day postoperative mortality was 4.8 %. At median follow-up of 33 (interquartile range 20.1-54.8) months, 5-year OS was inferior in transfused patients (45.9 vs. 61.0 %; p < 0.0001). Five-year RFS was decreased with RBCT (15.5 vs. 31.6 %; p < 0.0001). The difference persisted when considering only 90-day survivors for 5-year OS (53.1 vs. 61.9 %, p = 0.023) and RFS (15.6 vs. 31.6 %; p < 0.0001). After adjustment for prognostic factors, RBCT was independently associated with decreased OS (hazard ratio 2.24; 95 % confidence interval 1.60-3.15) and RFS (hazard ratio 1.71; 95 % confidence interval 1.28-2.28). CONCLUSIONS: Perioperative RBCT is independently associated with decreased OS and RFS following hepatectomy for CRLM. Interventions to minimize and rationalize the use of RBCT for hepatectomy are warranted to mitigate this detrimental effect on long-term outcomes.

Enteral Nutrition Support Reduces the Necessity of Total Parenteral Nutrition to Reach Patient-Specific Caloric Goals Postpancreaticoduodenectomy.

OBJECTIVES: Pancreaticoduodenectomy (PD) is associated with significant rates of postoperative complications. Although there is evidence that enteral nutrition support (ENS) may reduce postoperative sepsis, the true value of ENS in the abrogation of septic complications remains controversial. The aim of our study is to investigate the postoperative outcome of patients post-PD with and without ENS. METHODS: Using our prospective institutional database, we identified 202 patients from 2001 through 2009 who underwent PD. Of the 202 patients, 121 matched our inclusion criteria. In total, 67 of 121 (55.4%) patients received ENS, whereas 54 (44.6%) patients had no ENS and served as controls. Postoperative morbidity and mortality were recorded and analyzed. RESULTS: No significant differences were found in the postoperative morbidity of the patients. The anastomotic leak rate was 13% in both the ENS and control groups (P = 0.846). There was no difference in mortality within the two groups (4% vs 5%, P = 0.881). Significantly more patients in the control group received total parenteral nutrition (P = 0.033). CONCLUSIONS: ENS is not associated with lower rates of postoperative morbidity and mortality. It does, however, reduce the necessity of additional total parenteral nutrition to reach patient-specific caloric goals.

The impact of portal pedicle clamping on survival from colorectal liver metastases in the contemporary era of liver resection: a matched cohort study.

INTRODUCTION: Portal pedicle clamping (PPC) may impact micro-metastases' growth. This study examined the association between PPC and survival after a hepatectomy for colorectal liver metastases (CRLM). METHODS: A matched cohort study was conducted on hepatectomies for CRLM at a single institution (2003-2012). Cohorts were selected based on PPC use, with 1:1 matching for age, time period and the Clinical Risk Score. Outcomes were overall and recurrence-free survival (OS and RFS). Cox regression was performed to assess the association between PPC and survival. RESULTS: Of 481 hepatectomies, 26.9% used PPC. One hundred and ten pairs of patients were matched in the cohorts. There was no significant difference in OS [hazard ratio (HR) 1.18; 95% confidence interval (CI): 0.76-1.83], with a 5-year OS of 57.8% (95%CI: 52.4-63.2%) with PPC versus 62.3% (95%CI: 57.1-67.5%) without. Five-year RFS did not differ (HR 0.98; 95%CI: 0.71-1.35) with 29.7% (95%CI: 24.9-34.5%) with PPC versus 28.0% (95%CI: 23.2-32.8%) without. When adjusting for extent of resection, transfusion, operative time and surgeon, there was no difference in OS (HR 0.91; 95%CI: 0.52-1.60) or RFS (HR: 0.86; 95%CI: 0.57-1.30). CONCLUSIONS: PPC was not associated with a significant difference in OS or RFS in a hepatectomy for CRLM. PPC remains a safe technique during hepatectomy.

Utility of preoperative imaging in evaluating colorectal liver metastases declines over time.

OBJECTIVES: Reports on the sensitivity and accuracy of contrast-enhanced helical computed tomography (HCT) in the preoperative evaluation of colorectal liver metastases (CLM) have been conflicting. Few studies have controlled for and reported on the time interval between HCT and eventual surgery. METHODS: A multi-institution, retrospective review of consecutive patients who underwent hepatic resection for CLM from January 1999 to September 2004 was conducted. Data regarding lesion characteristics and resectability were extracted from radiology reports, operative findings and histopathological records. Findings in HCT were evaluated according to their sensitivity for detecting CLM and ability to predict resectability. RESULTS: A total of 217 consecutive patients who underwent hepatic resection for CLM were identified. The overall sensitivity of HCT for detection of CLM was 83.2%. Prolonged time between imaging and surgery was a negative predictor for HCT sensitivity in univariate and multivariate analysis (P < 0.001). In predicting resectability, preoperative HCT was accurate 77.0% of the time. The time interval to surgery was negatively correlated with HCT prediction accuracy in univariate and multivariate analyses (P < 0.001). CONCLUSIONS: The utility of HCT as a preoperative tool to evaluate CLM is inversely proportional to the time interval between imaging and surgery. This may explain conflicting reports of the accuracy of HCT in the current literature.

Expression of epidermal growth factor receptor in primary colorectal adenocarcinoma predicts expression in recurrent disease.

We tested the usefulness of epidermal growth factor receptor (EGFR) immunostaining in primary colorectal adenocarcinoma as a predictor for EGFR status of tumor recurrences in 33 primary tumors and distant recurrences (July 1994 to June 2005). Representative primary and recurrent tumor sections were stained using mouse anti-EGFR antibodies, and only membranous staining of malignant cells was recorded. Results were reported as negative (no staining), 1+ (positivity in <50% of cells), or 2+ (positivity in >50% of cells). Of 33 cases, 19 (58%) showed the same extent of immunopositivity in primary and recurrent tumors. Bivariate logistic regression analysis of primary tumors with 2+ vs those with negative or 1+ staining showed that the primary tumor status had a major predictive relationship with that of recurrence (odds ratio, of 45.99; confidence limit, 4.0-524.9; P = .0021). The difference between the median time to recurrence of primary tumors with the various degrees of staining was not statistically significant. Our reporting method provides a useful correlation between the staining profiles of primary colorectal adenocarcinoma and recurrent disease. It is exceptionally reliable in predicting immunopositivity of a recurrence when more than 50% of cells of the primary tumor are immunoreactive.

Is EGFR expression altered following postoperative chemotherapy for colorectal adenocarcinoma?

BACKGROUND: There is immunohistochemical evidence to suggest that expression of epidermal growth factor receptor (EGFR) in primary colorectal adenocarcinoma predicts its expression in recurrent disease. This study investigates whether postoperative chemotherapy affects the degree of concordance between EGFR statuses of the two tumors. METHODS: Thirty-three patients were identified from the files of Sunnybrook Health Sciences Center from July 1994 to June 2005. All patients had resection of their primary tumors and their distant recurrences. Eighteen patients received postoperative chemotherapy, 3 of which also received postoperative radiation therapy. Representative primary and recurrent tumor sections were stained using mouse anti-EGFR antibodies and only membranous staining of malignant cells was recorded. Results were reported as negative (no staining), 1+ (positivity in <50% of cells) or 2+ (positivity in >50% of cells). RESULTS: EGFR immunostaining in the 15 patients, who received no postoperative chemotherapy, was decreased in 3 recurrences, remained the same in 10 and increased in 2. In the group of 18 patients who received postoperative chemotherapy, EGFR immunostaining was decreased in 6 recurrences, remained the same in 9 and increased in 3 (p = 0.6598). In patients who received postoperative chemotherapy, the odds ratio for a recurrence to show lower levels of EGFR immunostaining compared to its originally resected primary was 4.75 (CI = 0.94-26.73). CONCLUSION: These preliminary data suggest that recurrences following postoperative chemotherapy are likely to have lower levels of EGFR expression compared to cases who receive no chemotherapy. Although the difference of immunostaining profiles between the two groups was not statistically significant, this observation might impact the management of these patients by targeted biologic therapies and its practical implications need further validation in larger series.

The impact of red blood cell transfusions on perioperative outcomes in the contemporary era of liver resection.

BACKGROUND: Perioperative red blood cell transfusions (RBCTs) are common in patients undergoing partial hepatectomy. We sought to explore the relationship between RBCTs and posthepatectomy perioperative outcomes in the contemporary surgical era. METHODS: We reviewed all patients undergoing partial hepatectomy from 2003 to 2012. Primary outcome was 30-day major morbidity (MM). We compared patients who did and received perioperative RBCT (defined as from time of operation until 30 days postoperatively. Multivariate analysis was performed to identify factors associated with MM and duration of stay, using logistic and negative binomial regression. RESULTS: Among 712 patients, 16.8% experienced MM, of whom 53.3% received RBCT. Patients who received RBCT experienced MM more commonly (30.8% vs 11.1%; P < .001). On multivariate analysis, the only factors associated with MM were age (relative risk [RR], 1.03; 95% CI, 1.00-1.06), greater operative time (RR, 1.29; 95% CI, 1.11-1.50), and RBCT (RR, 3.57; 95% CI, 1.81-7.04). RBCT was associated independently with a greater duration of stay (RR, 1.47; 95% CI, 1.13-1.91). CONCLUSION: Receipt of RBCT is associated independently with perioperative MM and prolonged hospitalization after partial hepatectomy. These findings further the rationale supporting the need for a strategy of blood management to decrease the use of RBCT after hepatectomy.

Hypophosphatemia and recovery of post-hepatectomy liver insufficiency.

BACKGROUND: Hypophosphatemia (HP) is frequent following liver resection, and thought to represent use of phosphate during liver regeneration. We sought to evaluate the association of post-hepatectomy HP with liver insufficiency and recovery. METHODS: Liver resections were retrospectively reviewed from 2009 to 2012 at a single institution. We explored the relationship between HP (defined as serum phosphate ≤0.65 mmol/L), occurrence of initial liver insufficiency (ILI) [bilirubin >50 µmol/L, international normalized ratio (INR) >1.7 within 72 hours of surgery] and in-hospital recovery of ILI. Secondary outcomes included 30-day post-operative major morbidity (Clavien grade 3 and 4 complications), mortality, and re-admission. RESULTS: Among 402 patients, 223 (55.5%) experienced HP and 64 (15.9%) met our definition of ILI, of which 53 (82.8%) recovered. Length of stay, 30-day post-operative major morbidity, mortality, and re-admission were similar between patients with and without HP. Among patients with ILI, 44 (68.8%) experienced HP. Following ILI, patients with HP recovered more often than those with NP (90.9% vs. 65.0%; P=0.03). CONCLUSIONS: In patients who experience post-hepatectomy ILI, HP is associated with improved recovery, potentially indicating more efficient liver regeneration. Further studies should explore the usefulness of post-hepatectomy HP as an early prognostic factor of recovery from ILI.

The Effect of Early Postoperative Non-Steroidal Anti-Inflammatory Drugs on Pancreatic Fistula Following Pancreaticoduodenectomy.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) are used commonly for postoperative analgesia but can potentially impair healing. Their effect on pancreaticoduodenectomy (PD) outcomes is unknown. We sought to examine the impact of early postoperative NSAIDs on pancreatic fistula (PF) after PD. METHODS: We reviewed our prospective pancreatectomy database supplemented by medication administration records, including all PDs from 2002 to 2012. Primary outcome was occurrence of clinically significant (grade B-C) PF. Secondary outcomes included major morbidity (Clavien grade III-V) and 90-day mortality. Patients were compared based on early postoperative NSAID use (first 3 days following surgery) using univariate and multivariate analyses. Subgroup analyses were conducted based on NSAID type (COX-2 inhibitors and non-selective inhibitors). RESULTS: We included 251 PDs, of whom 127 (50.6%) patients received NSAIDs postoperatively (35.5% COX-2 inhibitors, 18.3% non-selective inhibitors, and 4.4% both). Use of any NSAIDs was associated with a non-significant increase in PF (16.5 vs 11.3%%; p = 0.23), and no difference in major morbidity and mortality. Use of non-selective inhibitors was not associated with an increase in PF (8.7 vs 15.1%; p = 0.256). COX-2 inhibitors were associated with increased PF (20.2 vs 10.5 %; p = 0.033), but no difference in major morbidity or mortality. After adjusting for Charlson comorbidity and estimated blood loss, use of COX-2 inhibitors was independently associated with PF (odds ratio 2.12; p = 0.044). CONCLUSIONS: COX-2 inhibitors are associated with PF in the early postoperative period. While non-selective inhibitors appear safe in this setting, caution is warranted with the use of COX-2 inhibitors.

Impact of fluid resuscitation on major adverse events following pancreaticoduodenectomy.

BACKGROUND: Pancreaticoduodenectomy remains a major undertaking with substantial perioperative morbidity and mortality. Previous studies in the colorectal population have noted a correlation between excessive postoperative fluid resuscitation and anastomotic complications. This study sought to assess the relationship between perioperative fluid management and clinical outcomes in patients undergoing pancreaticoduodenectomy. METHODS: Data from a single institution, prospective database over a 10-year period (2002 to 2012) were reviewed. Patients were compared for perioperative fluid balance and postoperative outcomes. Multivariable analysis was performed to assess the relationship between perioperative fluid administration and incidence of major adverse events. RESULTS: Higher positive fluid balance on postoperative day 0, postoperative day 1, and postoperative day 2 was associated with increased incidence of major adverse events, increased postoperative intensive care unit admission, and longer hospital stay. Higher positive fluid balance on postoperative day 0 was most strongly associated with postoperative morbidity (odds ratio 1.39, confidence interval 1.16 to 1.66, P = .0003). Fluid balance on postoperative day 3 was not associated with adverse events. CONCLUSIONS: Increased early perioperative fluid resuscitation is associated with major adverse events in patients undergoing pancreaticoduodenectomy. More restrictive fluid administration may improve postoperative outcomes; further prospective clinical trials focused on fluid resuscitation and goal-directed therapy are needed.

Prognostic factors in resected pancreatic adenocarcinoma: analysis of actual 5-year survivors.

BACKGROUND: Pancreatic cancer is a rapidly fatal disease with very few 5-year survivors even after aggressive surgical treatment. Our objective was to determine the actual 5-year survival rate of patients with pancreatic adenocarcinoma who underwent a resection with curative intent in 5 teaching hospitals within the University of Toronto system. We then sought to determine clinical and histopathologic features of 5-year survivors to determine factors associated with a favorable prognosis. STUDY DESIGN: A retrospective chart review was performed using surgeon and hospital databases to identify patients who had a surgical resection for pancreatic adenocarcinoma between January 1, 1988, and December 31, 1996. RESULTS: One hundred twenty-three patients who had a resection and a pathologic diagnosis of pancreatic adenocarcinoma with complete followup were identified from seven surgical practices. Mean survival (+/- standard error) in this series was 31.7 +/- 3.5 months (median 13.6 months). There were 18 5-year survivors (14.6%), including 5 patients (4.1%) who survived longer than 10 years. The survivors included 13 patients who had undergone a Whipple resection, 4 who had undergone a distal pancreatectomy, and 1 who had undergone a total pancreatectomy. Tumor size, lack of jaundice at presentation, negative nodal disease, low tumor grade, and a low tumor stage were all significant predictors of survival in univariate analysis (all p < 0.05). Only tumor stage (hazard ratio [95% confidence interval]: stage IIA 1.5 [0.8 to 2.8], stage IIB 2.6 [1.4 to 4.7], stage III 1.8 [0.8 to 4.3]) and tumor grade (hazard ratio [95% confidence interval]: moderately differentiated 1.6 [0.9 to 2.9], and poorly differentiated 3.1 [1.6 to 6.2]) were independently associated with survival differences in a multivariate Cox proportional hazards model. CONCLUSIONS: We conclude that longterm survival from pancreatic adenocarcinoma is possible if the disease is identified in its early stages. These and other similar data should provide further stimulus for the development and evaluation of novel screening strategies to improve early detection of this disease.

A novel approach to the intraoperative assessment of the uncinate margin of the pancreaticoduodenectomy specimen.

BACKGROUND: Currently, there is no consensus regarding the pancreaticoduodenectomy (PD) margins examined intraoperatively or the technical protocol for frozen section examination. The aim of this work was to summarize our experience regarding the intraoperative examination of the uncinate margin and to compare it with the published literature. MATERIALS AND METHODS: Our local protocol for the intraoperative assessment of the uncinate margin of the PD specimen is described in this article. A PubMed search limited to English language publications using terms along the theme of pancreaticoduodenectomy and margin was performed. Retrieved articles were categorized according to whether they discussed frozen section margin examination. RESULTS: Ten articles published between 1981 and 2005 were retrieved which discussed the intraoperative examination of PD specimens. Of the 10 articles, 5 discussed the intraoperative consultation for diagnostic purposes only, 2 discussed the consultation for both diagnostic purposes and assessment of margins, and 3 discussed intraoperative assessment of margins only. Of the total of five articles that discussed the intraoperative assessment of margins, none detailed the technical protocol for examining the uncinate margin. DISCUSSION: Our proposed protocol for the intraoperative assessment of the uncinate margin of PD specimens allows for its accurate evaluation and has not been described previously in the English literature.

Improved lymph node retrieval in Whipple specimens as a result of implementation of a new uncinate margin protocol.

BACKGROUND: Lymph node status is an important prognostic factor in pancreatic and peri-ampullary adenocarcinoma. We recently changed our protocol for assessment of the uncinate margin of Whipple specimens and noted that lymph nodes were often present in uncinate margin sections. MATERIALS AND METHODS: Whipple specimens from 2004 to 2006 were divided into two groups, those that were handled according to the en face protocol, and those handled according to the radial protocol. The numbers of lymph nodes found in uncinate margin sections were assessed, as well as the total number of nodes found in the specimen. RESULTS: Sixteen cases were handled according to the en face protocol, and 20 according to the radial protocol. In the en face group, 2 benign nodes were found in the uncinate margin (0.1 nodes per case), while in the radial group, 36 nodes (1.8 nodes per case) were identified (p=0.0005). Eight cases in the latter group had positive nodes in the uncinate margin sections. In two of these cases the positive lymph node was the only lymph node with metastasis, and in an additional case the involved node was one of two positive lymph nodes. Total lymph node retrieval was 15.5 lymph nodes per case in the en face group, and 20 nodes per case in the radial group (p=0.02). DISCUSSION: The improved lymph node retrieval may be due to additional nodes found in radial sections of the uncinate margin, or alternatively, due to increased vigilance in specimen handling. In 3 of 20 cases, nodes found in the radial sections influenced staging.

Combustion exhaust measurements of nitric oxide with an ultraviolet diode-laser-based absorption sensor.

A diode-laser-based sensor has been developed for ultraviolet absorption measurements of the nitric oxide (NO) molecule. The sensor is based on the sum-frequency mixing (SFM) of the output of a tunable, 395-nm external-cavity diode laser and a 532-nm diode-pumped, frequency-doubled Nd:YAG laser in a beta-barium borate crystal. The SFM process generates 325 +/- 75 nW of ultraviolet radiation at 226.8 nm, corresponding to the (v' = 0, v" = 0) band of the A2Sigma+-chi2II electronic transition of NO. Results from initial laboratory experiments in a gas cell are briefly discussed, followed by results from field demonstrations of the sensor for measurements in the exhaust streams of a gas turbine engine and a well-stirred reactor. It is demonstrated that the sensor is capable of fully resolving the absorption spectrum and accurately measuring the NO concentration in actual combustion environments. Absorption is clearly visible in the gas turbine exhaust even for the lowest concentrations of 9 parts per million (ppm) for idle conditions and for a path length of 0.51 m. The sensitivity of the current system is estimated at 0.23%, which corresponds to a detection limit of 0.8 ppm in 1 m for 1000 K gas. The estimated uncertainty in the absolute concentrations that we obtained using the sensor is 10%.

Minimising blood loss and transfusion requirements in hepatic resection.

BACKGROUND: Substantial blood loss and the requirement for blood transfusion remain major considerations for hepatic surgeons. We analysed the impact of a systematic protocol aimed at reducing intraoperative blood loss and homologous blood (HB) transfusion associated with hepatic resection. METHODS: Prospective clinical data were collected from 151 elective liver resections performed during the period between 1980 and 1999. Further data directly related to blood loss and anaesthesia were retrospectively collected from the anaesthetic intra-operative record. Strategies implemented in 1991 included preoperative autologous blood donation, low central venous pressure anaesthesia, aprotinin administration, ultrasonic dissection, hepatic vascular inflow occlusion and a Cell Saver. Blood loss and transfusion requirements were studied before and after the implementation of these strategies. RESULTS: There was no difference in the patient demographics, indications for operation or the scope of resections in the two time periods evaluated. Blood-saving strategies resulted in decreased estimated blood loss (4500 mL vs. 1000 mL p<0.001). In addition, the number of patients requiring transfusion decreased (91.8% vs. 25.5% respectively, p<0.001) and the mean number of units of HB transfusion was lower (I 3.7 vs. 2.3, p<0.001). Morbidity and mortality were also decreased (57.1% vs. 25.5%, p<0.001 and 10.2% and 4.9% p<0.001, respectively). No complications directly referrable to low CVP anesthesia were identified. CONCLUSION: Systematic implementation of strategies designed to control blood loss are effective and may reduce morbidity and mortality associated with hepatic resections.

Impact of lymph node retrieval and pathological ultra-staging on the prognosis of stage II colon cancer.

BACKGROUND AND OBJECTIVES: A minimum number of lymph nodes must be assessed for accurate diagnosis of stage II colon cancer. We assessed number of lymph nodes retrieved, pathological ultra-staging, and outcome in stage II colon cancer. MATERIALS AND METHODS: Consecutively treated patients with stage II colon cancer were identified. Baseline and outcome data were collected. Retrospective ultra-staging using lymphovascular invasion (LVI) and nodal micrometastases was performed. Patients were divided into two groups: group I had 6 nodes retrieved. Survival was analyzed. RESULTS: One hundred and fifteen patients were included in the study. The 5 year overall survival was worse in group I versus II (P = 0.03). LVI and micrometastases were identified but neither predicted survival. Disease failure in group I was due to distant metastases rather than local recurrence. CONCLUSIONS: Inadequate retrieval and assessment of lymph nodes is associated with worse outcome in stage II colon cancer patients. Recurrence patterns support the hypothesis that disease recurrence occurred due to inaccurate staging. In this small study, LVI or nodal micrometastases did not predict survival. Maximal attention should be paid to the total number of lymph nodes retrieved before embarking on potentially more resource intensive staging methods.