Modified 2-stage IPAA has similar postoperative complication rates and functional outcomes compared to 3-stage IPAA.

INTRODUCTION: Reconstructive ileal-pouch anal anastomosis (IPAA) for ulcerative colitis (UC) is often created in 3-stages: colectomy â€‹+ â€‹ileostomy, proctectomy â€‹+ â€‹pouch creation with diverting loop ileostomy, then subsequent ileostomy closure. Modified 2-stage IPAA is without pouch diversion, thus avoiding a third operation. This study compares perioperative complications, quality of life (QOL) and functional outcomes of 3- versus modified 2-stage IPAA. METHODS: Charts were reviewed for adult UC patients undergoing IPAA between 2010 and 2020. QOL and function were assessed with EQ-5D-3L Quality of Life and Pouch Functional Score questionnaires. RESULTS: 152 patients were identified. 43 modified 2-stage and 109 3-stage IPAA were similar for anastomotic leak (9.3% vs. 1.8%, p â€‹= â€‹0.06), SSI (34.9% vs. 29.7%, p â€‹= â€‹0.51) and ileus (32.6% vs. 33%, p â€‹= â€‹0.96). Modified 2-stage had less bowel obstruction than 3-stage IPAA (7.0% vs. 30.1%, p â€‹= â€‹0.006). 92 patients returned questionnaires with similar QOL and pouch function. CONCLUSIONS: Perioperative complications, QOL and function are similar for 3-stage IPAA and modified 2-stage IPAA. Modified 2-stage IPAA in select patients is safe and has less postoperative bowel obstruction than 3-stage IPAA.

A cost-utility study of elective haemorrhoidectomies in Canada.

AIM: The aim was to estimate the 10-year cost-utility of haemorrhoidectomy surgery with preference-based measures of health using Canadian health utility measures and costs. METHODS: Patients undergoing elective haemorrhoidectomies by general and colorectal surgeons in British Columbia, Vancouver, between September 2015 and November 2022, completed preoperatively and postoperatively the EuroQol five-dimension five-level health-related quality of life questionnaire (EQ-5D-5L). Quality-adjusted life years (QALYs) attributable to surgery were calculated by discounting preoperative and postoperative health utility values derived from the EQ-5D-5L. Costs were measured from a health system perspective which incorporated costs of hospital stay and specialists' fees. Results are presented in 2021 Canadian dollars. RESULTS: Of 94 (47%) patients who completed both the preoperative and postoperative questionnaires, the mean gain in QALYs 10 years after surgery was 1.0609, assuming a 3.5% annual discounting rate. The average cost of the surgery was $3166. The average cost per QALY was $2985 when benefits of the surgery were assumed to accrue for 10 years. The cost per QALY was higher for women ($3821) compared with men ($2485). Participants over the age of 70 had the highest cost per QALY ($8079/QALY). CONCLUSIONS: Haemorrhoidectomies have been associated with significant gains in health status and are inexpensive relative to the associated gains in quality of life based on patients' perspectives of their improvement in health and well-being.

Transanal Endoscopic Microsurgery (TEM) for rectal GI stromal tumor.

BACKGROUND: Transanal endoscopic microsurgery (TEM) is effective in treating adenomas and select early rectal cancers. Our objective is to evaluate TEM in treating early rectal GISTs. METHODS: Patients were identified in a prospective database with pathology confirmed rectal GIST prior to TEM over 10 years. Demographic, pathologic, operative and follow-up data was analysed and presented with descriptive statistics. RESULTS: 7 cases of rectal GIST were treated with TEM with a follow-up time of 31 months (0-71). Median tumor distance from the anal verge was 4 cm (2.5-6) and median tumor size was 3 cm (2-5.7). Negative margins were achieved in 4/7 patients. Those with positive margins were treated with repeat TEM or imatinib. 1 patient had local recurrence successfully treated by TEM. CONCLUSIONS: Overall, TEM is safe for locally excising GISTs. As rectal GISTs are rare, a multicenter registry may better elucidate outcomes with this treatment.

Surgical site infection in elective colonic and rectal resections: effect of oral antibiotics and mechanical bowel preparation compared with mechanical bowel preparation only.

AIM: Surgical site infections are disproportionately common after colorectal surgery and may be largely preventable. The objective of this retrospective cohort study was to determine the effect of oral antibiotics and mechanical bowel preparation on surgical site infections. METHOD: A retrospective study of a consecutive series of elective colonic and rectal resections following an Enhanced Recovery After Surgery pathway, which also included mechanical bowel preparation, from 1 September 2014 to 30 September 2017. The addition of oral antibiotics (neomycin and metronidazole) to the mechanical bowel preparation procedure was assessed. Development of surgical site infections within 30 days was the main outcome measured. The secondary outcome was assessment of possible surgical site infection predictors. RESULTS: Seven-hundred thirty-two patients were included: 313 (43%) preintervention (mechanical bowel preparation only); and 419 (57%) postintervention (mechanical bowel preparation plus oral antibiotics). Surgical site infection rates preintervention and. postintervention were: overall, 20.8% vs 10.5%, P < 0.001; superficial, 10.9% vs 4.3%, P < 0.001; and organ space, 9.9% vs 6.2%, P = 0.03. Subgroup analysis of colonic resections revealed a significant reduction in overall (17.1% vs 6.8%), superficial (10.7% vs 4.3%) and organ space (6.4% vs. 2.6%) infections. Rectal resections had significant reduction in overall (26.2% vs 15.3%) and superficial (11.1% vs 4.4%) infection rates but not in organ space infections (15.1% vs 10.9%). Multivariate regression analysis revealed open vs minimally invasive surgery (P < 0.001) and omission of oral antibiotics (P = 0.004) as independent predictors of surgical site infections. CONCLUSION: Administration of oral antibiotics resulted in significant reduction of superficial and organ space infections after colonic resection; after rectal resection, significant reduction only of superficial infections was found.

A multi-centre randomized controlled trial of open vs closed management of the rectal defect after transanal endoscopic microsurgery.

AIM: Transanal endoscopic microsurgery (TEM) is a technically challenging strategy that allows expanded indications for local excision of rectal lesions. Transluminal suturing is difficult, so open management of the resultant defect is appealing. Expert opinion suggests there is more pain when the defect is left open. The aim of this study was to determine if closure of the defect created during full thickness excision of rectal lesions with TEM leads to less postoperative pain compared to leaving the defect open. METHOD: At the time of surgery, patients undergoing a full thickness TEM were randomized to sutured (TEM-S) or open (TEM-O) management of the rectal defect. At five Canadian academic colorectal surgery centres, experienced TEM surgeons enrolled patients ≥ 18 years treated by full thickness TEM. The primary outcome was postoperative pain measured by the visual analogue scale. Secondary outcomes included postoperative pain medication use and 30-day postoperative complications, including bleeding, infection and hospital readmission. RESULTS: Between March 2012 and October 2013, 50 patients were enrolled and randomized to sutured (TEM-S, n = 28) or open (TEM-O, n = 22) management of the rectal defect. There was no difference between the two study groups in postoperative pain on postoperative day 1 (2.8 vs 2.6, P = 0.76), day 3 (2.8 vs 2.1, P = 0.23) and day 7 (2.8 vs 1.7, P = 0.10). CONCLUSION: In this multicentre randomized controlled trial, there was no difference in postoperative pain between sutured or open defect management in patients having a full thickness excision with TEM.

Salvage TME following TEM: a possible indication for TaTME.

BACKGROUND: Salvage surgery after transanal endoscopic microsurgery (TEM) has shown mixed results. Transanal total mesorectal excision (TaTME) might be advantageous in this population. The aim of this study was to assess the short-term oncologic and operative outcomes of salvage surgery after TEM, comparing TaTME to conventional salavge TME (sTME). METHODS: Consecutive patients treated with salvage surgery after TEM were identified. Patients who underwent TaTME were compared to those who had conventional sTME. The primary outcome was the ability to perform an appropriate oncologic procedure defined by a composite outcome (negative distal margins, negative radial margins and complete or near complete mesorectum specimen). RESULTS: During the study period, 41 patients had salvage surgery after TEM. Of those, 11 patients had TaTME while 30 patients had sTME. All patients in the TaTME group met the composite outcome of appropriate oncologic procedure compared to 76.7% for the conventional sTME group (p = 0.19). TaTME was associated with significantly higher rates of sphincter preservation (100 vs. 50%, p = 0.01), higher rates of laparoscopic surgery (100 vs. 23.3%, p < 0.001) and lower rates of conversion to open surgery (9.1 vs. 57%, p < 0.001). No difference was found in postoperative morbidity (36.3 vs. 36.7%, p = 0.77). CONCLUSIONS: The present study demonstrates that for patients requiring salvage surgery after TEM, TaTME is associated with significantly higher rates of sphincter-sparing surgery when compared to conventional transabdominal TME while producing adequate short-term oncologic outcomes. Salvage surgery after TEM might be a clear indication for TaTME rather than conventional surgery.

Randomized double-blind trial comparing the cosmetic outcome of cutting diathermy versus scalpel for skin incisions.

BACKGROUND: Controversy exists about whether cutting diathermy for skin incisions leads to a cosmetically inferior scar. Cosmetic outcomes were compared between skin incisions created with cutting diathermy versus scalpel. Wound infection rates and postoperative incisional pain were also compared. METHODS: This was a randomized double-blind trial comparing cutting diathermy and scalpel in patients undergoing bowel resection. Scar cosmesis was assessed at 6 months after surgery by a plastic surgeon and a research associate using the Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scale (POSAS). Patients also used POSAS to self-evaluate their scars. Wound infections within 30 days were recorded, and incision pain scores were measured on the first 5 days after operation. RESULTS: A total of 66 patients were randomized to cutting diathermy (31) or scalpel (35). At 6 months, there was no significant difference between the diathermy and scalpel groups in mean(s.d.) VSS scores (4·9(2·6) versus 5·0(1·9); P = 0·837), mean POSAS total scores (19·2(8·0) versus 20·0(7·4); P = 0·684) or subjective POSAS total scores (20·2(12·1) versus 21·3(10·4); P = 0·725). Neither were there significant differences in wound infection rates between the groups (5 of 30 versus 5 of 32; P = 1·000). Pain scores on day 1 after operation were significantly lower in the diathermy group (mean 1·68 versus 3·13; P = 0·018), but were not significantly different on days 2-5. CONCLUSION: Cutting diathermy is a cosmetically acceptable technique for abdominal skin incisions. There is no increased risk of wound infection, and diathermy may convey benefit in terms of early postoperative wound pain. REGISTRATION NUMBER: NCT01496404 ( http://www.clinicaltrials.gov).

Differences between referred and nonreferred patients in cancer research.

BACKGROUND: In Canada, provincial cancer registries have been established to provide rigorous population-based data for patients with colorectal cancer. Databases maintained by regional cancer agencies contain a broader scope of information and have been used as a surrogate source of information for colorectal cancer research. It is unclear whether these data can be reliably extrapolated to all patients affected by colorectal cancer. We sought to determine whether patients included in a referral-based database are systematically different from patients who are not included. METHODS: We conducted a retrospective cohort study to compare patients referred to the British Columbia Cancer Agency with those who were not referred. Comparison was based on age, sex and geographic location. We used univariate and logistic regression analysis to identify significant differences between the cohorts. RESULTS: Univariate analysis demonstrated that the referral and nonreferral cohorts differed in sex, age and geographic location. For patients with rectal cancer, the referral and nonreferral cohorts varied in age and geographic location. Multivariate analysis demonstrated significant differences in age and geographic location but not sex for patients with colon and rectal cancer. CONCLUSION: Patients included in the referral database differed in age and geographic location from those included only in the provincial database. Studies using large data sets from referral centres must be interpreted with caution and may not be representative of the entire patient population.

CONTEXTE: Au Canada, on a établi des registres provinciaux en oncologie pour générer des données représentatives rigoureuses au sujet des patients atteints de cancer colorectal. Les bases de données maintenues par les agences régionales du cancer contiennent un éventail plus large de renseignements et ont servi de source de données de substitution pour la recherche sur le cancer colorectal. Or, on ignore s'il est possible d'extrapoler ces données de manière fiable à tous les patients atteints de cancer colorectal. Nous avons voulu déterminer si les patients inclus dans une base de données de référence sont systématiquement différents des patients qui n'y figurent pas. MÉTHODES: Nous avons procédé à une étude de cohorte rétrospective pour comparer les patients référés à l'agence de lutte contre le cancer de la Colombie-Britanniqueà ceux qui n'y avaient pas été référés. La comparaison reposait sur l'âge, le sexe et l'emplacement géographique. Nous avons utilisé une analyse de régression univariée et logistique pour dégager les différences significatives entre les cohortes. RÉSULTATS: L'analyse univariée a démontré que les cohortes référée et non référée différaient aux plans du sexe, de l'âge et de l'emplacement géographique. Pour les patients atteints d'un cancer rectal, les cohortes référée et non référée variaient selon l'âge et l'emplacement géographique. L'analyse multivariée a révélé des différences significatives aux plans de l'âge et de l'emplacement géographique, mais non au plan du sexe en ce qui concerne les patients atteints de cancer du côlon et du rectum. CONCLUSION: Les patients inclus dans la base de données de référence étaient différents de ceux qui ne figuraient que dans la base de données provinciale, pour ce qui est de l'âge et de l'emplacement géographique. Il faut interpréter avec prudence lesétudes reposant sur d'importantes séries de données provenant de centres de référence, car elles pourraient ne pas être représentatives de toute la population de patients.

Assessment of sonographic quality of anal sphincter muscles in patients with faecal incontinence.

OBJECTIVE: The main application of endoanal ultrasonography (US) in evaluation of faecal incontinence is to identify surgically correctable sphincter defects. The aim of our study was to determine whether qualitative changes in echogenicity and in uniformity of internal (IAS) and external (EAS) anal sphincter muscles detected on endoanal US correlate with other anal laboratory tests and modified Wexner faecal incontinence functional score. METHOD: Records on 99 patients having complete information on anorectal manometry, faecal incontinence scoring and available endoanal US imaging of the anal sphincters were included in statistical analysis. Anatomic appearance and changes in echogenicity of the anal sphincter muscles were recorded according to the proposed scoring system. Endoanal US defect and quality component scores for IAS and EAS as well as the total score were correlated with anal laboratory tests and incontinence score using Spearman's correlations test. RESULTS: There was a trend for correlation between IAS quality score and incontinence score (P = 0.06), but no correlation for IAS defect score. EAS defect score had a significant negative correlation with maximum squeeze pressure (MSP) (P = 0.031). Distal EAS quality score had a significant correlation with incontinence score (P = 0.002). EAS total score correlated with MSP (P = 0.02) and incontinence score (P = 0.006). Endoanal US total score was significantly correlated with incontinence score (P = 0.006), maximal resting (MRP) (P = 0.035) and MSP (P = 0.045) and high pressure anal canal zone length (P = 0.03). CONCLUSION: Sonographic morphology of anal sphincter muscles correlates with anal laboratory tests and functional incontinence score. Qualitative ultrasound scoring instrument may improve evaluation of patients with faecal incontinence.

Imaging findings of unusual anorectal and perirectal pathology: a multi-modality approach.

The objective of this review is to discuss the less common causes of rectal and perirectal disease with an emphasis on their differentiating radiological features and the importance of a multimodality imaging approach. Radiologists should be aware of the ultrasound, computed tomography, and magnetic resonance imaging appearances of the wide variety of uncommon lesions arising from the rectal and perirectal regions that may simulate adenocarcinoma in order to render an accurate diagnosis and facilitate appropriate management.

Predictors of positive radial margin status in a population-based cohort of patients with rectal cancer.

BACKGROUND: Surgical margin status is an important predictor of risk of relapse among patients with rectal cancer. METHODS: Patients referred to the British Columbia Cancer Agency for consideration of adjuvant therapy for rectal adenocarcinoma were included. Predictors of margin positivity were determined from uni- and multivariate analysis. RESULTS: Among 340 patients, 83% had negative resection margins. In 268 patients with resectable tumours, a significantly higher rate of margin positivity was observed in low rectal tumours (32.2%) as compared with mid-rectal (3.9%) and high rectal (14.3%) tumours. Among 59 patients with locally advanced rectal cancer treated with preoperative radiation (with or without chemotherapy), 32% with low tumours had margin positivity. Of patients with T4 tumours, 50% (11/22) had a positive resection margin. CONCLUSIONS: In a population cohort, distal-third rectal location, locally advanced presentation, and T4 cancer represent subgroups for whom further improvement in therapy is required.

Results of curative surgery and postoperative chemoradiation for rectal adenocarcinoma in British Columbia, 1985 to 1994.

OBJECTIVE: To assess factors affecting survival and pelvic recurrence after surgery and postoperative chemoradiation for rectal cancer in order to design improved management strategies. DESIGN: A chart review. SETTING: The British Columbia Cancer Agency. PATIENTS: One hundred and ninety-one consecutive patients who had rectal cancer treated between 1985 and 1994. Median follow-up was 39 months. INTERVENTIONS: Surgical excision of the cancer with intent to cure followed by chemoradiation. OUTCOME MEASURES: Multivariate analysis, to determine whether survival and pelvic recurrence were affected by tumour stage, nodal status, type of surgical procedure and presence of residual disease, and the quality of pathology reporting with respect to evaluation of radial resection margins and number of lymph nodes examined. RESULTS: Overall 5-year disease-specific survival was 60% and pelvic recurrence was 25%. Survival was affected by tumour stage (p < 0.02), nodal status (p < 0.001), type of surgical procedure (p < 0.04), presence of residual disease (p < 0.02) and pelvic recurrence (p < 0.0001). Pelvic recurrence was affected by the presence of residual disease (p < 0.001) but not by tumour stage (p < 0.14), nodal status (p < 0.37) or type of surgcial procedure (p < 0.20). Radial margins were evaluated in 44% of pathology reports and the median number of lymph nodes assessed was 6. CONCLUSIONS: Survival was most significantly affected by pelvic recurrence. Strategies to minimize pelvic recurrence including preoperative radiation and the principle of careful mesorectal excision to maximize the achievement of negative radial resection margins and negative residual disease are recommended. Also needed are standards for evaluating radial margins and lymph nodes to improved pathology reports.

Enteral feeding decreases gut apoptosis, permeability, and lung inflammation during murine endotoxemia.

We tested the hypothesis that endotoxemia and fasting are associated with increased gut apoptotic activity, gut permeability, and inflammation in a distant organ. Fed or fasted CD-1 mice were studied 6 h after intraperitoneal injection of either saline (sham) or endotoxin (4 mg/kg of 0111:B4 Escherichia coli lipopolysaccharide). We found that endotoxin increased gut caspase-3 and -6 activity by 4.9 +/- 0.6- and 4.5 +/- 0.5-fold, respectively (P < 0.001), and increased terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) staining of mucosal cells (P < 0.05). Feeding decreased caspase-3 activity by 40% (P < 0.05) and decreased endotoxin-induced TUNEL staining (P < 0.05). Endotoxin increased gut poly(ADP-ribose) polymerase activity by 15% (P < 0.05). Endotoxin increased gut permeability by 44% (P < 0.05), an effect reduced 36% by feeding (P < 0.05). Similarly, endotoxin increased pulmonary neutrophil infiltration (6.0 +/- 1.0-fold, P < 0.001) and increased lung interleukin (IL)-6 (5.9 +/- 0.1-fold, P < 0.001) and macrophage inflammatory protein (MIP)-2 expression (290 +/- 40-fold, P < 0.001), whereas feeding decreased this effect by 43% for neutrophils, 40% for IL-6 (P < 0.05), and 35% for MIP-2 (P < 0.05). Thus endotoxin increases gut apoptotic activity, gut permeability, and pulmonary inflammation. Enteral feeding may decrease the distant organ inflammation by reducing gut apoptosis, thereby maintaining gut mucosal function during endotoxemia.

Initial management of trauma by a trauma team: effect on timeliness of care in a teaching hospital.

The objective of this study was to determine if timeliness of care would improve after implementation of the team approach in trauma management in a single teaching hospital. To make this determination, we used a before-and-after retrospective cohort series for a 550-bed teaching and tertiary referral hospital that was not a level 1 trauma center. We included all patients who presented to the Emergency Department and who were admitted to St. Paul's Hospital because of trauma during 2 baseline months (May and November 1987; n = 111) and 2 follow-up months (May and November 1990; n = 142). In 1988, a formal trauma team was developed to coordinate the care of trauma patients who were seen in the Emergency Department. Indications for calling the trauma team were based on the criteria of the American College of Surgeons for triage to a trauma center. We calculated elapsed time from assessment in the Emergency Department to arrival of the trauma surgeon, discharge from the Emergency Department, and arrival of the patient in the operating room (for urgent or emergent surgery). We also determined the Revised Trauma Score, the Injury Severity Score (1985 version), the crude mortality ratio, and the Z statistic (population outcome comparison). After implementation of the trauma team, median elapsed time from initial nursing assessment in the Emergency Department to arrival in the operating Room for blunt trauma patients decreased from 11.33 to 4.82 hours (P = .05), but there were no significant differences in any other measures of timeliness, crude mortality, or adjusted mortality. We conclude that implementation of a trauma team in a teaching hospital is associated with a minimal effect on timeliness of care for admitted trauma patients.

Techniques and complications of ileostomy takedown.

OBJECTIVE: We use a loop ileostomy for temporary fecal diversion because of ease of technical construction and assumed low complication rate. Here, we review our complications of loop ileostomy and takedown using three techniques of closure. METHODS: We reviewed charts of all patients who had temporary ileostomies constructed during 1987 to 1995 (n = 366). Ileostomy takedown was performed in 339 patients using one of three closure techniques: enterotomy suture (65%), resection with handsewn anastomosis (20%), and stapled anastomosis (15%). Complications were recorded for pre-takedown and 30-day post-takedown intervals. RESULTS: Overall complication rate was 28%. Pre-takedown complications occurred in 21 patients (5.7%), including small bowel obstruction (2.5%) and dehydration/electrolyte derangement (2.2%). Post-takedown complications occurred in 83 patients (24.5%), including wound infection (14.2%), small bowel obstruction (5%), anastomotic leak (2.9%), and 1 death from a cardiac event. Post-takedown obstruction was higher for closure using resection with sutured anastomosis (12%) compared with enterotomy suture (2.3%), P < or = 0.003. Stapled anastomosis had an intermediate rate of obstruction (7.7%). Anastomotic leak was similar between closure techniques. CONCLUSIONS: Loop ileostomy and takedown are associated with low rates of serious complications (5% or less). As such, we continue to advocate use of loop ileostomy as a diversion procedure. Closure by enterotomy suture is preferred over resection. However, if resection is required, closure by stapled anastomosis is preferred over suture anastomosis.

The effects of retroperitoneal carbon dioxide insufflation on hemodynamics and arterial carbon dioxide.

BACKGROUND: Laparoscopic techniques are being increasingly used for retroperitoneal surgery. However, hemodynamic and ventilatory efforts of retroperitoneal carbon dioxide (CO2) insufflation have not been studied. We hypothesized that differences in absorptive surface, anatomy, and compartment compliance could result in different hemodynamic and ventilatory effects between retroperitoneal and intraperitoneal insufflation. METHODS: Pigs (n = 7) were anesthetized and stabilized. The peritoneal cavity was incrementally insufflated with CO2 to a maximum pressure of 25 cm H2O and the gas released. Hemodynamics and arterial blood gas values were recorded initially, at each level of insufflation, and following the pneumoperitoneum release until baseline values were reached. This insufflation protocol was repeated in the retroperitoneum. RESULTS: Mean arterial pressure (111 mm Hg, 95% confidence interval 99 to 156) and cardiac output (3.7 L/min, 2.8 to 5.2) did not change with increasing insufflation pressure of either intraperitoneum or retroperitoneum. PaCO2 was directly related to insufflation pressure in both spaces, increasing from 41.2 mm Hg (37.3 to 43.4) at baseline to 57.7 mm Hg (47.6 to 82.1) at insufflation pressure of 25 cm H2O. After release of the insufflation gas, time to return to baseline PaCO2 was slightly less from the retroperitoneal space (73 minutes, 45 to 105) than the intraperitoneal (107 minutes, 35 to 175). CONCLUSIONS: The effects of CO2 insufflation on hemodynamics and PaCO2 are the same in the retroperitoneal and intraperitoneal spaces.

Effect of crystalloid administration on oxygen extraction in endotoxemic pigs.

We asked whether crystalloid administration improves tissue oxygen extraction in endotoxicosis. Four groups of anesthetized pigs (n = 8/group) received either normal saline infusion or no saline and either endotoxin or no endotoxin. We measured whole body (WB) and gut oxygen delivery and consumption during hemorrhage to determine the critical oxygen extraction ratio (ERO2 crit). Just after onset of ischemia (critical oxygen delivery rate), gut was removed for determination of area fraction of interstitial edema and capillary hematocrit. Radiolabeled microspheres were used to determine erythrocyte transit time for the gut. Endotoxin decreased WB ERO2 crit (0.82 +/- 0.06 to 0.55 +/- 0.08, P < 0.05) and gut ERO2 crit (0.77 +/- 0.07 to 0.52 +/- 0.06, P < 0.05). Unexpectedly, saline administration also decreased WB ERO2 crit (0.82 +/- 0.06 to 0.62 +/- 0.08, P < 0.05) and gut ERO2 crit (0.77 +/- 0.07 to 0.67 +/- 0.06, P < 0.05) in nonendotoxin pigs. Saline administration increased the area fraction of interstitial space (P < 0.05) and resulted in arterial hemodilution (P < 0.05) but not capillary hemodilution (P > 0.05). Saline increased the relative dispersion of erythrocyte transit times from 0.33 +/- 0.08 to 0.72 +/- 0.53 (P < 0.05). Thus saline administration impairs tissue oxygen extraction possibly by increasing interstitial edema or increasing heterogeneity of microvascular erythrocyte transit times.