Small bowel obstruction in older patients: challenges in surgical management.

BACKGROUND: Small bowel obstruction (SBO) is a common disease affecting all segments of the population, including the frail elderly. Recent retrospective data suggest that earlier operative intervention may decrease morbidity. However, management decisions are influenced by surgical outcomes. Our goal was to determine the current surgical management of SBO in older patients with particular attention to frailty and the timing of surgery. STUDY DESIGN: A retrospective review of patients over the age of 65 with a diagnosis of bowel obstruction (ICD-10 K56*) using the 2016 National Inpatient Sample (NIS). Demographics included age, race, insurance status, medical comorbidities, and median household income by zip code. Elixhauser comorbidities were used to derive a previously published frailty score using the NIS dataset. Outcomes included time to operation, mortality, discharge disposition, and hospital length of stay. Associations between demographics, frailty, timing of surgery, and outcomes were determined. RESULTS: 264,670 patients were included. Nine percent of the cohort was frail; overall mortality was 5.7%. Frail had 1.82 increased odds of mortality (95% CI 1.64-2.03). Hospital LOS was 1.6 times as long for frail patients; a quarter of the frail were discharged home. Frail patients waited longer for surgery (3.58 days vs 2.44 days; p < 0.001). Patients transferred from another facility had increased mortality (aOR 1.58; 95% CI 1.36-1.83). There was an increasing mortality associated with a delay in surgery. CONCLUSION: Patients with frailty and SBO have higher mortality, more frequent discharge to dependent living, longer hospital length of stay, and longer wait to operative intervention. Mortality is also associated with male gender, black race, transfer status from another facility, self-pay status, and low household income. Every day in delay in surgical intervention for those who underwent operations led to higher mortality. If meeting operative indications, older patients with bowel obstruction have a higher chance of survival if they undergo surgery earlier.

Reaction time measures of non-chromatic contamination in opponent stimuli.

Simple visual reaction times (RTs) are highly sensitive to the presence of transient activity. Transient and sustained visual mechanisms generate different RT versus contrast functions because they have different gains. To identify non-chromatic (transient) activity, we can compare RT versus contrast functions obtained with either fast or slow onset stimuli. To test this, the stimulus adopted was a temporal modulation along the red-green axis, introducing non-chromatic components by varying the red-green ratio. The technique was sensitive to departures from isoluminance for all observers; therefore, we present this method as a way to detect transient contamination in a chromatic stimulus.

The next frontier of acute care general surgery: fellowship training.

Acute care surgery (ACS) is an area of surgical specialization within general surgery and a model for clinical care delivery that has proliferated over the last 2 decades. Models of ACS in Canada exist in both academic and community settings and are used to manage patients in need of emergency general surgery (EGS) care, with or without the provision of trauma care. The implementation of the ACS model has changed the landscape of patient care, surgical education and the workforce, providing an option for some general surgeons to exclude EGS care from their regular practice. The rise of ACS as a concentration of surgical skill and content expertise has resulted in the establishment of dedicated ACS fellowship training programs. This is a landmark in the evolution of general surgery, as well as a stepping stone on the path to improving patient care, surgical education and scholarly endeavour in this field.

Operating room use for emergency general surgery cases: analysis of the Patterns of Complex Emergency General Surgery in Canada study.

BACKGROUND: Access to the operating room (OR) is variable among emergency general surgery (EGS) services, with some having dedicated EGS ORs, and others only a shared queue. Currently in Canada, only a limited number of acute care surgery services have dedicated daytime operating room (OR) access; hence, we aimed to describe the burden of after-hours EGS operating in Canada and differences associated with OR access. METHODS: In this multicentre retrospective cohort study, we used data from a previously conducted study designed to evaluate nonappendiceal, nonbiliary disease across 8 Canadian hospitals. We performed a secondary analysis to describe booking priorities and timing of operative interventions, compare sites with and without access to a dedicated EGS daytime OR, and identify differences in morbidity and mortality based on timing of operative intervention. RESULTS: Among 1244 patients, operations were performed during weekday daytime in 521 cases (41.9%), in the evening in 279 (22.4%), on the weekend in 293 (23.6%) and overnight in 151 (12.1%). Operating room booking priority was more than 2 hours to 8 hours in 657 cases (52.8%), more than 8 hours to 24 hours in 334 (26.9%) and more than 24 hours to 48 hours in 253 (20.3%). Substantial variation in booking priority was observed for the same preoperative diagnoses. Sites with dedicated EGS ORs performed a greater proportion of cases during daytime versus overnight compared to sites without dedicated EGS ORs (198/237 [83.5%] v. 323/435 [74.2%], p = 0.006). No significant differences in outcome were found between cases performed during the daytime, evening and overnight. CONCLUSION: We found considerable variation in OR booking priority within the same preoperative diagnoses among EGS patients in Canada. Sites with dedicated EGS ORs performed more cases during weekday daytime compared to sites without dedicated EGS ORs; however, this study showed no evidence of compromised outcomes based on OR timing.

David V. Feliciano: Contributions to acute care surgery.

SummaryDr. David Feliciano is a surgical triple threat whose contributions to the practice, research and teaching of trauma care have rarely been matched. Canadians benefit from his willingness to educate the country's clinical trauma surgeons and surgeon-scientists from coast to coast.

Resuscitative endovascular balloon occlusion of the aorta in Canada: a context-specific position paper from the Canadian Collaborative for Urgent Care Surgery (CANUCS).

SummaryResuscitative endovascular balloon occlusion of the aorta (REBOA) is a well-described intervention for noncompressible torso hemorrhage. Several Canadian centres have included REBOA in their hemorrhagic shock protocols. However, REBOA has known complications and equipoise regarding its use persists. The Canadian Collaborative on Urgent Care Surgery (CANUCS) comprises surgeons who provide acute trauma care and leadership in Canada, with experience in REBOA implementation, use, education and research. Our goal is to provide evidence- and experience-based recommendations regarding institutional implementation of a REBOA program, including multidisciplinary educational programs, attention to device and care pathway logistics, and a robust quality assurance program. This will allow Canadian trauma centres to maximize patient benefits and minimize risks of this potentially life-saving technology.

Failure to rescue in emergency general surgery in Canada.

BACKGROUND: The risk of death after a postoperative complication - known as failure to rescue (FTR) - has been proposed to be superior to traditional benchmarking outcomes, such as complication and mortality rates, as a measure of system quality. The purpose of this study was to identify the current FTR rate in emergency general surgery (EGS) centres across Canada. We hypothesized that substantial variability exists in FTR rates across centres. METHODS: In this multicentre retrospective cohort study, we performed a secondary analysis of data from a previous study designed to evaluate operative intervention for nonappendiceal, nonbiliary disease by 6 EGS services across Canada (1 in British Columbia, 1 in Alberta, 3 in Ontario and 1 in Nova Scotia). Patients underwent surgery between Jan. 1 and Dec. 31, 2014. We conducted univariate analyses to compare patients with and without complications. We performed a sensitivity analysis examining the mortality rate after serious complications (Clavien-Dindo score 3 or 4) that required a surgical intervention or specialized care (e.g., admission to intensive care unit). RESULTS: A total of 2595 patients were included in the study cohort. Of the 206 patients who died within 30 days, 145 (70.4%) experienced a complication before their death. Overall, the mortality rate after any surgical complication (i.e., FTR) was 16.0%. Ranking of sites by the traditional outcomes of complication and mortality rates differed from the ranking when FTR rate was included in the assessment. CONCLUSION: There was variability in FTR rates across EGS services in Canada, which suggests that there is opportunity for ongoing quality-improvement efforts. This study provides FTR benchmarking data for Canadian EGS services.

Comparison of macaque and human L- and M-cone driven electroretinograms.

PURPOSE: The macaque retina is often used as a model for the human retina. However, there are only a handful of direct in vivo comparisons of the retinal physiology in humans and macaques. In the current study, ERG responses to luminance, L-cone isolating and M-cone isolating stimuli with sinusoidal, sawtooth and square wave temporal profiles were measured. The results were compared with those obtained from human observers. METHODS: The responses from five anesthetized adult macaques were measured. Full field stimuli were created. L- and M-cone isolating stimuli were based on the triple silent substitution technique. Sinusoidal stimuli had temporal frequencies between 4 and 56 Hz in 4 Hz steps. Sawtooth stimuli with rapid-on ramp-off and with rapid-off ramp-on excitation profiles had a frequency of 4 Hz. Square stimuli were presented at 2 Hz. RESULTS: Macaque and human ERGs in response to L- and M-cone isolating stimuli reflect L/M opponency and luminance activity. In responses to sine waves, cone opponency dominates at low temporal frequencies (4-12 Hz); luminance dominates at high temporal frequencies. The responses to sawtooth and square wave stimuli reflect a mixture of chromatic and luminance activity. L:M response ratios vary between individuals both in macaques and humans. Macaques show more complex responses, including greater second harmonic contributions than those in humans. CONCLUSIONS: Macaque and human ERGs share basic underlying mechanisms reflecting L/M opponency and luminance activity. There may be quantitative differences possibly reflecting differences in contributions of inner retinal mechanisms to the ERGs.

Incidence of Intra-Abdominal Hypertension and Abdominal Compartment Syndrome: A Systematic Review.

OBJECTIVE: To determine the contemporary prevalence of intra-abdominal hypertension (IAH) and abdominal compartment syndrome in critically ill patients. DATA SOURCES: Medline, Embase, and Central databases. STUDY SELECTION: Studies reporting on the prevalence of IAH in consecutively admitted critically ill patients using the World Society of Abdominal Compartment Syndrome (WSACS) consensus guidelines for intra-abdominal pressure (IAP) measurement. DATA EXTRACTION: Duplicate independent review and data abstraction. DATA SYNTHESIS: The search identified 2428 titles with 6 eligible studies (n = 1965). Reported prevalence ranged from 30% to 49%. Despite abiding by the WSACS guidelines for IAP measurement, studies varied in their definition of IAH, frequency and duration of IAP measurement, and reporting of outcomes. Three of 6 studies reported that IAH, especially at higher grades, was an independent predictor of mortality. CONCLUSIONS: Intra-abdominal hypertension is a common finding in critically ill patients and may be associated with increased mortality, especially at higher grades. Further prospective research is required to examine the effect of screening and treatment of IAH on patient outcomes.

Drug use in Canadian patients with trauma after cannabis legalization.

Background: The federal Cannabis Act came into force on Oct. 17, 2018, in Canada, making Canada only the second country in the world to legalize the cultivation, acquisition, possession and consumption of cannabis and its by-products. This provided a unique opportunity to evaluate the impact of this legislation on drug-related trauma. Methods: We performed a prospective observational study on the use of cannabis and other illicit drugs in the trauma population at a lead Canadian trauma centre in London, Ontario, in the 3 months before (July 1 to Sept. 30, 2018) and 3 months after (Nov. 1, 2018, to Jan. 31, 2019) the legalization of cannabis in Canada. We defined cannabis use as a positive cannabinoid screen result at the time of assessment by the trauma team. We also screened for opioids, amphetamines and cocaine. Results: A total of 210 patients were assessed by our trauma service between July 1 and Sept. 30, 2018, and 141 patients were assessed between Nov. 1, 2018, and Jan. 31, 2019. Motor vehicle collisions were the most common cause of trauma both before (101 [48.1%]) and after (67 [47.5%]) legalization. The mean Injury Severity Score was 17.6 (standard deviation [SD] 13.0) and 19.7 (SD 14.8), respectively. Drug screens were done in 88 patients (41.9%) assessed before legalization and 99 patients (70.2%) assessed after legalization. There was no difference in the rate of positive cannabinoid screen results before and after legalization (22 [25%] v. 22 [22%]). There was a trend toward higher rates of positive cannabinoid screen results (2/10 [20%] v. 5/8 [62%]) and positive toxicology screen results (5/10 [50%] v. 6/8 [75%]) after legalization among patients with penetrating trauma, but our sample was too small to achieve statistical significance. Conclusion: We found no difference in the rates of positive cannabinoid screen results among patients assessed at our trauma centre in the 3 months before and the 3 months after legalization of cannabis; however, there was a trend toward an increase in the rates of positive results of toxicology screens and cannabinoid screens among those with penetrating trauma. These preliminary single-centre data showing no increased rates of cannabis use in patients with trauma after legalization are reassuring.

Contexte: La Loi fédérale sur le cannabis est entrée en vigueur ici le 17 octobre 2018, faisant du Canada le second pays à légaliser la culture, l'acquisition, la possession et la consommation du cannabis et de ses produits dérivés. Cette situation fournit une occasion unique d'évaluer l'impact de cette loi sur les traumatismes liés aux drogues. Méthodes: Nous avons procédé à une étude d'observation prospective sur la consommation du cannabis et d'autres drogues illicites chez une population de victimes de traumatismes dans un grand centre canadien de traumatologie de London, en Ontario, au cours des 3 mois précédant (1er juillet au 30 septembre 2018) et des 3 mois suivant (1er novembre 2018 au 31 janvier 2019) la légalisation du cannabis au Canada. La consommation de cannabis était confirmée par l'obtention de résultats positifs aux tests de dépistage des cannabinoïdes demandés par l'équipe de traumatologie. Nous avons aussi effectué un dépistage des opioïdes, des amphétamines et de la cocaïne. Résultats: En tout, notre service de traumatologie a vu 210 patients entre le 1er juillet et le 30 septembre 2018, et 141 entre le 1er novembre 2018 et le 31 janvier 2019. Les accidents de la route ont été la plus fréquente cause de traumatisme avant (101 [48,1 %]) et après (67 [47,5 %]) la légalisation. L'indice moyen de gravité des blessures a été de 17,6 (écart-type [É.-T.] 13,0) et 19,7 (É.-T. 14,8), respectivement. Un dépistage de drogues a été effectué chez 88 patients (41,9 %) vus avant la légalisation et chez 99 patients (70,2 %) vus après la légalisation. On n'a observé aucune différence quant aux taux de résultats positifs aux tests de dépistage des cannabinoïdes enregistrés avant et après la légalisation (22 [25 %] c. 22 [22 %]). Les taux de résultats positifs aux tests de dépistage des cannabinoïdes (2/10 [20 %] c. 5/8 [62 %]) et aux tests toxicologiques (5/10 [50 %] c. 6/8 [75 %]) ont eu tendance à être plus élevés après la légalisation chez les patients victimes de traumatismes pénétrants, mais notre échantillon était trop petit pour atteindre une portée statistique. Conclusion: Nous n'avons observé aucune différence quant aux taux de résultats positifs au dépistage des cannabinoïdes au cours des 3 mois précédant et suivant la légalisation du cannabis; par contre, les taux de résultats positifs aux tests de dépistage des drogues et du cannabis ont eu tendance à être plus élevés chez les victimes de traumatismes pénétrants. Ces données préliminaires provenant d'un seul centre qui ne montrent pas d'augmentation des taux de consommation de cannabis chez les polytraumatisés sont rassurantes.

Chest Tube Insertion Among Surgical and Nonsurgical Trainees: How Skilled Are Our Residents?

BACKGROUND: Competency-based medical education has renewed focus on the attainment and evaluation of resident skill. Proper evaluation is crucial to inform educational interventions and identify residents in need of increased training and supervision. Currently, there is a paucity of studies rigorously evaluating resident chest tube insertion skill. MATERIALS AND METHODS: Residents of all training levels before their intensive care unit rotation or currently rotating through the intensive care unit were invited to participate. Trainees inserted a thoracostomy tube on a high-fidelity simulator. Their performances were recorded and scored by blinded raters using the validated TUBE-iCOMPT rubric. Surgical and nonsurgical residents were compared. RESULTS: Forty-nine residents participated; 30 from nonsurgical and 19 from surgical training programs. Overall, trainees were most deficient in the "preprocedural checks" and "patient positioning and local anesthetic" domains. Surgical trainees demonstrated higher chest tube insertion skill than their nonsurgical peers (median total score 88 [interquartile range, 74-90] versus 75 [interquartile range, 66-85], respectively, P = 0.01), particularly in the "patient positioning" and "blunt dissection" domains (P = 0.01 and P = 0.03, respectively). These differences were no longer significant when controlled for experience and Advanced Trauma Life Support certification. CONCLUSIONS: Overall, surgical residents were more skilled than nonsurgical residents in tube thoracostomy placement. Relative skill deficits within the domains of chest tube insertion have also been identified among residents of different specialties. These areas can be targeted with educational interventions to improve resident performance, and ultimately, patient safety.

Anomalous pupillary responses to M-cone onsets are linked to ${\rm L}{:}{\rm M}$L:M ratio.

M-cone stimulation induces a pupil constriction to stimulus offset, whereas, with L cones, the pupil responds conventionally with a constriction to onset. To test the possibility that this paradox is linked to the ${\rm L}{:}{\rm M}$L:M ratio, we measured the strength of the effect by injecting a variable amount of positive or negative luminance contamination on either side of M-cone isolation and identifying a balance point at which the pupil responded equally to onset and offset. Nineteen individuals were recruited. In observers with low ${\rm L}{:}{\rm M}$L:M ratio, the paradoxical effect was weak. There was a significant relationship (${{r}^2} = {0.561}$r2=0.561) between the balance point and ${\rm L}{:}{\rm M}$L:M ratio. The effect is likely to be linked to strong inhibitory signals associated with cone-opponent pathways.

Patterns of complex emergency general surgery in Canada.

BACKGROUND: Most of the literature on emergency general surgery (EGS) has investigated appendiceal and biliary disease; however, EGS surgeons manage many other complex conditions. This study aimed to describe the operative burden of these conditions throughout Canada. METHODS: This multicentre retrospective cohort study evaluated EGS patients at 7 centres across Canada in 2014. Adult patients (aged ≥ 18 yr) undergoing nonelective operative interventions for nonbiliary, nonappendiceal diseases were included. Data collected included information on patients' demographic characteristics, diagnosis, procedure details, complications and hospital length of stay. Logistic regression was used to identify predictors of morbidity and mortality. RESULTS: A total of 2595 patients were included, with a median age of 60 years (interquartile range 46-73 yr). The most common principal diagnoses were small bowel obstruction (16%), hernia (15%), malignancy (11%) and perianal disease (9%). The most commonly performed procedures were bowel resection (30%), hernia repair (15%), adhesiolysis (11%) and débridement of skin and soft tissue infections (10%). A total of 47% of cases were completed overnight (between 5 pm and 8 am). The overall inhospital mortality rate was 8%. Thirty-three percent of patients had a complication, with independent predictors including increasing age (p = 0.001), increasing American Society of Anesthesiologists score (p = 0.02) and transfer from another centre (p = 0.001). CONCLUSION: This study characterizes the epidemiology of nonbiliary, nonappendiceal EGS operative interventions across Canada. Canadian surgeons are performing a large volume of EGS, and conditions treated by EGS services are associated with a substantial risk of morbidity and mortality. Results of this study will be used to guide future research efforts and set benchmarks for quality improvement.

CONTEXTE: La plupart des études sur les services de chirurgie générale d'urgence (CGU) s'intéressent seulement aux atteintes de l'appendice et de la vésicule biliaire. Pourtant, les chirurgiens du domaine traitent beaucoup d'autres problèmes complexes. L'objectif de l'étude était de décrire le travail chirurgical associé à ces problèmes dans l'ensemble du Canada. MÉTHODES: Notre étude de cohorte rétrospective multicentrique inclut les patients adultes (≥ 18 ans) qui ont subi en 2014 une opération non planifiée pour une atteinte qui ne touchait ni l'appendice ni la vésicule biliaire dans 1 des 7 centres sélectionnés, répartis un peu partout au pays. Nous avons recueilli les données suivantes : renseignements de base des patients, diagnostic, détails de l'intervention, nature des complications et durée d'hospitalisation. Puis nous avons dégagé les facteurs prédictifs de morbidité et de mortalité en appliquant un modèle de régression logistique. RÉSULTATS: L'échantillon totalisait 2595 patients, pour un âge médian de 60 ans (écart interquartile 46­73 ans). Les diagnostics principaux les plus courants étaient l'occlusion de l'intestin grêle (16 %), la hernie (15 %), la tumeur maligne (11 %) et les lésions périanales (9 %). Les interventions les plus fréquentes étaient la résection de l'intestin (30 %), la réparation d'une hernie (15 %), le débridement (11 %) et le débridement de tissus mous ou cutanés infectés (10 %). L'opération a eu lieu le soir ou la nuit (entre 17 h et 8 h) dans 47 % des cas. Le taux global de mortalité à l'hôpital était de 8 %. Des complications sont survenues chez 33 % des patients, dont les facteurs prédictifs indépendants étaient l'âge avancé (p = 0,001), un score ASA (de l'American Society of Anesthesiologists) élevé (p = 0,02) et le transfert à partir d'un autre centre (p = 0,001). CONCLUSION: Cette étude dresse le profil épidémiologique des interventions effectuées par les services de CGU du Canada en présence d'atteintes autres que celles de l'appendice et de la vésicule biliaire. Les chirurgiens du pays font beaucoup d'interventions générales urgentes, pour traiter des affections associées à un risque élevé de morbidité et de mortalité. Les résultats de l'étude guideront les prochaines recherches et serviront de points de référence en matière d'amélioration de la qualité.

A 30-day prospective audit of all inpatient complications following acute care surgery: How well do we really perform?

Background: Acute care surgery (ACS) and emergency general surgery (EGS) services must provide timely care and intervention for patients who have some of the most challenging needs. Patients treated by ACS services are often critically ill and have both substantial comorbidities and poor physiologic reserve. Despite the widespread implemention of ACS/EGS services across North America, the true postoperative morbidity rates remain largely unknown. Methods: In this prospective study, inpatients at 8 high-volume ACS/EGS centres in geographically diverse locations in Canada who underwent operative interventions were followed for 30 days or until they were discharged. Readmissions during the 30-day window were also captured. Preoperative, intraoperative and postoperative variables were tracked. Standard statistical methodology was employed. Results: A total of 601 ACS/EGS patients were followed for up to 30 inpatient or readmission days after their index emergent operation. Fifty-one percent of patients were female, and the median age was 51 years. They frequently had substantial medical comorbidities (42%) and morbid obesity (15%). The majority of procedures were minimally invasive (66% laparoscopic). Median length of stay was 3.3 days and the early readmission (< 30 d) rate was 6%. Six percent of patients were admitted to the critical care unit. The overall complication and mortality rates were 34% and 2%, respectively. Cholecystitis (31%), appendicitis (21%), bowel obstruction (18%), incarcerated hernia (12%), gastrointestinal hemorrhage (7%) and soft tissue infections (7%) were the most common diagnoses. The morbidity and mortality rates for open surgical procedures were 73% and 5%, respectively. Conclusion: Nontrauma ACS/EGS procedures are associated with a high postoperative morbidity rate. This study will serve as a prospective benchmark for postoperative complications among ACS/EGS patients and subsequent quality improvement across Canada.

Contexte: Les services de chirurgie dans les unités de soins actifs (CSA) et de chirurgie générale dans les services d'urgence (CGSU) doivent fournir rapidement des soins et des interventions à des patients dont les besoins sont parmi les plus complexes. En effet, les patients pris en charge par les services de CSA sont souvent gravement malades et présentent des comorbidités sur fond de faible réserve physiologique. Même si les services de CSA/CGSU se sont répandus en Amérique du Nord, les taux réels de morbidité postopératoire demeurent pour une bonne part inconnus. Méthodes: Dans cette étude prospective, on a suivi pendant 30 jours ou jusqu'à leur congé, les patients hospitalisés pour des interventions chirurgicales dans 8 centres de CSA/CGSU achalandés de divers endroits au Canada. On a également tenu compte des réadmissions dans les 30 jours. Les paramètres pré-, per- et postopératoires ont été enregistrés. Une méthodologie statistique standard a été appliquée. Résultats: En tout, 601 patients de CSA/CGSU ont ainsi été suivis pendant une durée allant jusqu'à 30 jours d'hospitalisation ou de réadmission après leur intervention urgente initiale. Cinquante et un pour cent étaient de sexe féminin et l'âge moyen était de 51 ans. Ces patients étaient nombreux à présenter des comorbidités de nature médicale substantielles (42 %) et une obésité morbide (15 %). La majorité des interventions ont été minimalement effractives (66 % laparoscopiques). La durée médiane des séjours a été de 3,3 jours et le taux de réadmission précoce (< 30 j) a été de 6 %. Six pour cent des patients ont été admis aux soins intensifs. Les taux globaux de complications et de mortalité ont été respectivement de 34 % et de 2 %. Cholécystite (31 %), appendicite (21 %), obstruction intestinale (18 %), hernie incarcérée (12 %), hémorragie digestive (7 %) et infections des tissus mous (7 %) comptent parmi les diagnostics les plus fréquents. Les taux de morbidité et de mortalité dans les cas de chirurgies ouvertes ont été respectivement de 73 % et 5 %. Conclusion: Les interventions de CSA/CGSU non liées à la traumatologie sont associées à un taux de morbidité postopératoire élevé. Cette étude fournira un ensemble de valeurs de références pour l'étude prospective des complications chez les patients pris en charge par les services de CSA/CGSU et l'amélioration subséquente des soins partout au Canada.

Vascular trauma: Does experience in the United States apply to a Canadian centre?

Summary: Trauma care has evolved similarly in the United States and Canada over the last 3 decades. Like much of modern trauma care, management of vascular trauma has been influenced by combat surgery experiences in recent wars. The American Association for the Surgery of Trauma sponsored the Prospective Observational Vascular Injury Treatment (PROOVIT) registry to document changes in the treatment of vascular trauma and determine outcomes in the US. However, differences in trauma populations and trauma systems between Canada and the US need to be considered. Here we compare the vascular trauma experience at a Canadian level I trauma centre over a 5-year period to the data in the PROOVIT registry.

Intra-Abdominal Hypertension Is More Common Than Previously Thought: A Prospective Study in a Mixed Medical-Surgical ICU.

OBJECTIVES: To determine the prevalence of intra-abdominal hypertension in mixed medical-surgical critically ill patients using modern definitions and measurement techniques. Secondarily to determine variables associated with intra-abdominal hypertension and ICU mortality. DESIGN: A prospective observational study. SETTING: Single institution trauma, medical and surgical ICU in Canada. PATIENTS: Consecutive adult patients admitted to the ICU (n = 285). INTERVENTION: Intra-abdominal pressure measurements twice a day during admission to the ICU. MEASUREMENTS AND MAIN RESULTS: In 285 patients who met inclusion criteria, 30% were diagnosed with intra-abdominal hypertension at admission and a further 15% developed intra-abdominal hypertension during admission. The prevalence of abdominal compartment syndrome was 3%. Obesity, sepsis, mechanical ventilation, and 24-hour fluid balance (> 3 L) were all independent predictors for intra-abdominal hypertension. Intra-abdominal hypertension occurred in 28% of nonventilated patients. Admission type (medical vs surgical vs trauma) was not a significant predictor of intra-abdominal hypertension. Overall ICU mortality was 20% and was significantly higher for patients with intra-abdominal hypertension (30%) compared with patients without intra-abdominal hypertension (11%). Intra-abdominal hypertension of any grade was an independent predictor of mortality (odds ratio, 3.33; 95% CI, 1.46-7.57). CONCLUSIONS: Intra-abdominal hypertension is common in both surgical and nonsurgical patients in the intensive care setting and was found to be independently associated with mortality. Despite prior reports to the contrary, intra-abdominal hypertension develops in nonventilated patients and in patients who do not have intra-abdominal hypertension at admission. Intra-abdominal pressure monitoring is inexpensive, provides valuable clinical information, and there may be a role for its routine measurement in the ICU. Future work should evaluate the impact of early interventions for patients with intra-abdominal hypertension.

Carbon monoxide and hydrogen sulphide reduce reperfusion injury in abdominal compartment syndrome.

BACKGROUND: Carbon monoxide (CO)- and hydrogen sulphide-releasing molecules (CORM-3 and GYY4137, respectively) have been shown to be potent antioxidant and antiinflammatory agents at the tissue and systemic level. We hypothesized that both CORM-3 and GYY4137 would reduce the significant organ dysfunction associated with abdominal compartment syndrome (ACS). MATERIAL AND METHODS: Randomized trial was conducted where ACS was maintained for 2 hours in 27 rats using an abdominal plaster cast and intraperitoneal CO2 insufflation at 20 mmHg. Three experimental groups underwent ACS and received an experimental molecule at the time of decompression: inactive CORM-3, active CORM-3, and GYY4137, whereas three groups underwent no ACS to serve as a sham. Sinusoidal perfusion, inflammatory response and cell death were quantified in exteriorized livers. Respiratory, liver, and renal dysfunction was assessed biochemically. RESULTS: Hepatocellular death and the number of activated leukocytes within postsinusoidal venules were significantly increased in rats with ACS (16-fold increase, 17-fold leukocyte activation, respectively, P < 0.05). Administration of CORM-3 or GYY4137 resulted in a significant decrease of both parameters (P = 0.03 and P = 0.009). ACS resulted in an increase in markers of renal and liver injury; CORM-3 or GYY4137 partially restored levels to those seen in sham animals. Myeloperoxidase was significantly elevated in the ACS group in lung, liver, and small intestine (P = 0.0002, P = 0.01, and P = 0.08, respectively). CORM-3 treatment, but not GYY4137, was able to completely block the response (65 ± 11 U/ml and 92 ± 18 U/ml, respectively versus 110 ± 10U/ml in the ACS group, lung tissue). CONCLUSIONS: We have demonstrated the effect of two molecules, CO and hydrogen sulphide, on tempering the reperfusion-associated metabolic and organ derangements in ACS. CORM-3 demonstrated a greater effect than GYY4137 and was able to restore most of the measured parameters to levels comparable to sham.

Rod- versus cone-driven ERGs at different stimulus sizes in normal subjects and retinitis pigmentosa patients.

PURPOSE: To study how rod- and cone-driven responses depend on stimulus size in normal subjects and patients with retinitis pigmentosa (RP), and to show that comparisons between responses to full-field (FF) and smaller stimuli can be useful in diagnosing and monitoring disorders of the peripheral retina without the need for lengthy dark adaptation periods. METHOD: The triple silent substitution technique was used to isolate L-cone-, M-cone- and rod-driven ERGs with 19, 18 and 33% photoreceptor contrasts, respectively, under identical mean luminance conditions. Experiments were conducted on five normal subjects and three RP patients. ERGs on control subjects were recorded at nine different temporal frequencies (between 2 and 60 Hz) for five different stimulus sizes: FF, 70°, 60°, 50° and 40° diameter circular stimuli. Experiments on RP patients involved rod- and L-cone-driven ERG measurements with FF and 40° stimuli at 8 and 48 Hz. Response amplitudes were defined as those of the first harmonic component after Fourier analysis. RESULTS: In normal subjects, rod-driven responses displayed a fundamentally different behavior than cone-driven responses, particularly at low temporal frequencies. At low and intermediate temporal frequencies (≤ 12 Hz), rod-driven signals increased by a factor of about four when measured with smaller stimuli. In contrast, L- and M-cone-driven responses in this frequency region did not change substantially with stimulus size. At high temporal frequencies (≥ 24 Hz), both rod- and cone-driven response amplitudes decreased with decreasing stimulus size. Signals obtained from rod-isolating stimuli under these conditions are likely artefactual. Interestingly, in RP patients, both rod-driven and L-cone-driven ERGs were similar using 40° and FF stimuli. CONCLUSION: The increased responses with smaller stimuli in normal subjects to rod-isolating stimuli indicate that a fundamentally different mechanism drives the ERGs in comparison with the cone-driven responses. We propose that the increased responses are caused by stray light stimulating the peripheral retina, thereby allowing peripheral rod-driven function to be studied using the triple silent substitution technique at photopic luminances. The method is effective in studying impaired peripheral rod- and cone- function in RP patients.

Paradoxical pupil responses to isolated M-cone increments.

M-cone onsets appear dimmer than the background and elicit electroretinograms (ERGs) resembling the light offset response. We sought a corresponding anomalous pupillary light reflex (PLR) using a 4-primary ganzfeld as stimulator and pupillometer. Increments and decrements of white light were compared with M- and L-cone onsets and offsets using silent substitution. Luminance bias (LB) could be added to or subtracted from the cone-isolating stimuli. There was a normal PLR to L-cone increments, but the pupil constricted mainly to M-cone decrements. Changing LB produced a neutral point where on and off responses were balanced. The results reflect ERG and psychophysical studies. This observation may be linked to the antagonistic nature of the M-cone input to cone opponent mechanisms.