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Biomedical subjects

William J Sibbald

Publications and source records attributed to William J Sibbald.

At least 19 recordsLinked to original sources
PubMed2006

Hospital volume and mortality for mechanical ventilation of medical and surgical patients: a population-based analysis using administrative data.

OBJECTIVE: In an effort to improve efficiency and quality of care, regionalization of adult critical care services, similar to trauma and neonatal intensive care, has been suggested. However, there is little research to understand if hospitals with higher patient volumes have better outcomes. Our objective is to determine whether hospital volume is associated with improved survival for medical or surgical patients receiving mechanical ventilation. DESIGN: Population-based retrospective cohort study. SETTING: Province of Ontario, Canada. PATIENTS: A total of 13,846 medical and 6,373 surgical patients receiving mechanical ventilation for greater than two consecutive days between 1998 and 2000. INTERVENTIONS: None. MEASUREMENTS: Odds ratio for death within 30 days of initiation of mechanical ventilation was calculated in relation to hospital volume of ventilation. Estimates were adjusted for patient demographics, diagnoses, and urgency status; hospital region and rural location; and accounted for clustering within hospitals. MAIN RESULTS: There was no effect of volume on mortality for surgical patients. After adjustment for clustering, among medical patients, the lowest-volume category (<100 episodes/yr) had a nonsignificant increase in mortality, with an odds ratio (95% confidence interval) of 1.13 (0.87-1.47) compared with the highest-volume category (> or =700 episodes/yr). A post hoc analysis revealed that within the lowest-volume category, the proportion of patients transferred to larger hospitals was 81% for hospitals with <20 episodes/yr and only 32% for hospitals with 20-99 episodes/yr, with odds ratios (95% confidence interval) for mortality of 0.74 (0.49-1.12) and 1.18 (0.90-1.54), respectively, compared with the highest-volume category. CONCLUSIONS: For surgical patients requiring mechanical ventilation for >2 days, hospital volume had no effect on mortality. For medical patients, higher mortality may occur in a subgroup of low-volume hospitals that do not routinely transfer their patients to larger-volume facilities. This finding needs further investigation in a larger-sized study.

Aged↗
PubMed2006

Intensive care and emergency medicine: progress over the past 25 years.

Over the last quarter of a century, intensive care medicine has developed into an established hospital specialty with its own unique identity and characteristics. Significant advances have occurred, mostly in a succession of small steps rather than any dramatic leap, with many being linked to advances in health care across other disciplines. In addition, many changes have resulted from the scientific identification of the detrimental effects of certain traditional practices once thought to be therapeutic. Here, in an attempt to learn from the past and offer guidance for future progress, we detail some of the key changes in various aspects of intensive care medicine including respiratory, cardiovascular, metabolic, and nutritional care, as well as sepsis, polytrauma, organization, and management.

Cardiovascular Diseases↗
PubMed2005

Differential inducible nitric oxide synthase activity in circulating neutrophils vs. mononuclears of septic shock patients.

OBJECTIVE: To compare nitric oxide synthase (NOS) activity in circulating neutrophils and mononuclear cells of patients with septic shock to healthy subjects. DESIGN AND SETTING: Prospective study in the general intensive care unit (30 beds) of a university affiliated-hospital and the A.C. Burton Vascular Biology Research Laboratory. PATIENTS: Six septic patients and seven healthy volunteers. MEASUREMENTS AND RESULTS: We measured NOS in circulating neutrophils and mononuclears. Constitutive (cNOS) and inducible (iNOS) activities were analyzed by the [3H]L-arginine-L-citrulline assay. Plasma NOx- was determined by chemiluminescence. NOx- was higher in septic vs. controls (median 110, IQR 39-250 vs. 23, 14-46 microM; p<0.05). cNOS in septic cells was unmeasurable. iNOS in septic neutrophils was higher (median 34.9, IQR 10.4-95.8 vs. controls 2.5, 0-2.7 U; p<0.05) while iNOS in septic mononuclears was unaltered (median 16.4, IQR 9.1-52.6 vs. controls 8.9, 5.9-20.3 U; p=0.240). CONCLUSIONS: Increased iNOS activity was found in circulating neutrophils of septic shock patients compared to healthy volunteers. Moreover, differential iNOS activity was evident in circulating neutrophils vs. mononuclears of patients with septic shock. Further investigations are warranted to confirm this differential iNOS activity and to explore its significance.

Hospitals, University↗
PubMed2005

Projected incidence of mechanical ventilation in Ontario to 2026: Preparing for the aging baby boomers.

OBJECTIVE: The aging baby boomers are expected to have a significant impact on the healthcare system. Mechanical ventilation is an age-dependent, costly, and relatively nondiscretionary medical service that may be particularly affected by the aging population. We forecast the future incidence of mechanical ventilation to the year 2026 to understand the impact of aging baby boomers on critical care resources. DESIGN: Population-based, sex-specific, and age-specific mechanical ventilation incidences for adults for the year 2000 were directly standardized to population projections to estimate the incidence of mechanical ventilation, in 5-yr intervals, from 2006 to 2026. Sensitivity analyses were performed by varying population projections and mechanical ventilation incidence for the elderly. SETTING: Province of Ontario, Canada. PATIENTS: Noncardiac surgery, mechanically ventilated adults. INTERVENTIONS: None. MAIN RESULTS: The projected number of ventilated patients in 2026 was 34,478, representing an 80% increase from 2000. The crude incidence increased 31%, from 222 to 291 per 100,000 adults. The annually compounded projected growth rate during this 26-yr period was 2.3%, similar to the actual growth rate experienced in the 1990s. The projected incidence was relatively insensitive to changes in assumptions, with estimates for 2026 ranging from 31,473 to 36,313 ventilated adults. CONCLUSIONS: The incidence of mechanical ventilation projected to the year 2026 will steadily increase and outpace population growth as occurred in the 1990s. In the current environment in which intensive care unit resources are limited and ventilated patients already use a significant proportion of acute care resources, planning for this continued growth is necessary. Existing evidence-based strategies that improve both the efficiency and efficacy of critical care services should be carefully evaluated for widespread implementation.

Adult↗
PubMed2004

Shockingly complex: the difficult road to introducing new ideas to critical care.

Resuscitation of critically ill patients with trauma or sepsis continues to challenge clinicians. Early imperatives include diagnostic judgment as to the presenting problem - sepsis or trauma. Subsequently, the clinician decides on the phase of resuscitation required for support - 'ebb' versus 'flow'. Finally, the clinician needs to determine what therapeutic strategies to employ and then judge when resuscitation is complete. Shortcomings of current approaches to determining the adequacy of circulatory resuscitation have prompted the evaluation of new technologies purported to directly assess microcirculatory flow as a clinical endpoint for the adequacy of resuscitation. While early studies are intriguing, this technology requires much more study before it can be considered for widespread adoption by the clinician.

Critical Care↗
PubMed2004

Transmission of severe acute respiratory syndrome during intubation and mechanical ventilation.

Nosocomial transmission of severe acute respiratory syndrome from critically ill patients to healthcare workers has been a prominent and worrisome feature of existing outbreaks. We have observed a greater risk of developing severe acute respiratory syndrome for physicians and nurses performing endotracheal intubation (relative risk [RR], 13.29; 95% confidence interval [CI], 2.99 to 59.04; p = 0.003). Nurses caring for patients receiving noninvasive positive-pressure ventilation may be at an increased risk (RR, 2.33; 95% CI, 0.25 to 21.76; p = 0.5), whereas nurses caring for patients receiving high-frequency oscillatory ventilation do not appear at an increased risk (RR, 0.74; 95% CI, 0.11 to 4.92; p = 0.6) compared with their respective reference cohorts. Specific infection control recommendations concerning the care of critically ill patients may help limit further nosocomial transmission.

Adult↗
PubMed2004

Multicentre, cluster-randomized clinical trial of algorithms for critical-care enteral and parenteral therapy (ACCEPT).

BACKGROUND: The provision of nutritional support for patients in intensive care units (ICUs) varies widely both within and between institutions. We tested the hypothesis that evidence-based algorithms to improve nutritional support in the ICU would improve patient outcomes. METHODS: A cluster-randomized controlled trial was performed in the ICUs of 11 community and 3 teaching hospitals between October 1997 and September 1998. Hospital ICUs were stratified by hospital type and randomized to the intervention or control arm. Patients at least 16 years of age with an expected ICU stay of at least 48 hours were enrolled in the study (n = 499). Evidence-based recommendations were introduced in the 7 intervention hospitals by means of in-service education sessions, reminders (local dietitian, posters) and academic detailing that stressed early institution of nutritional support, preferably enteral. RESULTS: Two hospitals crossed over and were excluded from the primary analysis. Compared with the patients in the control hospitals (n = 214), the patients in the intervention hospitals (n = 248) received significantly more days of enteral nutrition (6.7 v. 5.4 per 10 patient-days; p = 0.042), had a significantly shorter mean stay in hospital (25 v. 35 days; p = 0.003) and showed a trend toward reduced mortality (27% v. 37%; p = 0.058). The mean stay in the ICU did not differ between the control and intervention groups (10.9 v. 11.8 days; p = 0.7). INTERPRETATION: Implementation of evidence-based recommendations improved the provision of nutritional support and was associated with improved clinical outcomes.

APACHE↗
PubMed2004

Tissue oxygen delivery and the microcirculation.

In health, acute anemia is accompanied by changes in the distribution of blood flows at all of the central, regional, and microcirculatory levels. This redistribution in blood flows provides the capacity to maintain tissue oxygenation with hematocrit as low as 21%. What is not known with certainty is whether the capacity to maintain tissue oxygenation in the presence of acute anemia can be influenced significantly by concurrent disease such as sepsis and cardiac disease. The single clinical trial found an apparent survival benefit by not exposing patients with sepsis to blood transfusions until the hemoglobin concentration was less than 70 g/L. The question remains as to whether this observation was the consequence of a protective effect anemia or an injurious effect of transfusing old stored blood.

Anemia↗
PubMed2004

Pseudomonas pneumonia-mediated sepsis induces expression of pancreatitis-associated protein-I in rat pancreas.

Severe impairment of exocrine pancreatic secretion has recently been demonstrated in a clinical study in sepsis and septic shock patients. The purpose of this study was to further evaluate involvement of the pancreas in the acute phase reaction in sepsis. Using a normotensive rat model of Pseudomonas pneumonia-induced sepsis, we assessed the expression of PAP-I, amylase and trypsinogen mRNA, PAPI protein levels, and cytokine expression in the pancreas by Northern and Western blot analysis and RT-M PCR, respectively. Presence of several well-established features of pancreatitis in sepsis-induced animals were examined by biochemical and histopathological methods as well as by a determination of both water and myeloperoxidase content. Sepsis resulted in an up-regulation of PAP-I gene expression and increase in its protein level in pancreas while the mRNA levels of amylase and trypsinogen were down-regulated. Differences in the pancreatic cytokine expression, serum amylase and serum lipase levels, the occurrence of pancreatic edema as well as the severity of inflammatory infiltration and necrosis were not significantly different between sham and pneumonia groups. Acinar cells showed increased vacuolization in pneumonia animals 24 hours after the treatment. These findings demonstrate that the pancreas is actively involved in the acute phase reaction in sepsis of remote origin. This involvement occurs without concomitant biochemical and histopathologic alterations observed in pancreatitis. Taken all together, these features are indicative of a sepsis-specific dysfunction of the pancreas.

Acute-Phase Reaction↗
PubMed2004

Mechanical ventilation in Ontario, 1992-2000: incidence, survival, and hospital bed utilization of noncardiac surgery adult patients.

OBJECTIVE: Mechanical ventilation is a common therapy used in caring for critically ill patients, but its epidemiology is poorly understood. We describe population-based, temporal trends in the incidence, survival, and hospital bed utilization of mechanically ventilated, noncardiac surgery adult patients. DESIGN: Retrospective, observational cohort study using linked administrative databases. SETTING: Province of Ontario, Canada. PATIENTS: Subjects were 150,755 unique patients who received mechanical ventilation between 1992 and 2000. INTERVENTIONS: None. MEASUREMENTS: Annual measures of mechanical ventilation incidence, 30-day patient mortality rate, and number of mechanical ventilation days and inpatient days for mechanically ventilated patients as a proportion of total adult inpatient bed days. MAIN RESULTS: From 1992 to 2000, the crude and age- and gender-adjusted incidence of mechanical ventilation increased 9% (p <.001) and 2% (p <.027), respectively, to 217 per 100,000 adults. Crude mortality rate 30 days after initiation of mechanical ventilation increased from 27% to 32% (p <.001). Significant predictors of 30-day mortality rate (adjusted hazard ratio, 95% confidence interval) were calendar year (1.03, 1.02-1.03), age >80 yrs (2.3, 2.2-2.3), Charlson score 3+ (2.0, 2.0-2.1), and specific diagnosis. From 1992 to 2000, the number of mechanical ventilation days and inpatient days for mechanically ventilated patients, as a proportion of total adult inpatient bed days, increased 69% and 30% (both p <.001), respectively, to 1.8% and 6.2%. CONCLUSIONS: There was a small, but important, increase in mechanical ventilation incidence and a substantial increase in the proportion of inpatient bed days used by mechanically ventilated patients in Ontario during the 1990s. These trends are important in planning for expansion of health care resources to meet the needs of the aging population. The increase, over time, in risk-adjusted mortality rate of mechanically ventilated patients is concerning and requires further investigation.

Adult↗
PubMed2003

Effect of nitric oxide on capillary hemodynamics and cell injury in the pancreas during Pseudomonas pneumonia-induced sepsis.

Sepsis-induced nitric oxide (NO) overproduction has been implicated in a redistribution of flow from the pancreas making it vulnerable to ischemic injury in septic shock. To test this hypothesis in a remote injury model of normotensive sepsis, we induced Pseudomonas pneumonia in the rat and used intravital video microscopy (IVVM) of the pancreas to measure functional capillary density, capillary hemodynamics [red blood cell (RBC) velocity, lineal density, and supply rate], and lethal cellular damage (propidium iodine staining) at 6 and 24 h after the induction of pneumonia. With pneumonia, plasma nitrite/nitrate [NO2(-)/NO3(-)(NOx(-))] levels were doubled by 21 h (P < 0.05). To assess the effect of NO overproduction on microvascular perfusion, N6-(1-iminoethyl)-L-lysine (L-NIL) was administered to maintain NOx(-) levels at baseline. Pneumonia did cause a decrease in RBC velocity of 23% by 6 h, but by 24 h RBC velocity and supply rate had increased relative to sham by 22 and 38%, respectively (P < 0.05). L-NIL treatment demonstrated that this increase was due to NO overproduction. With pneumonia, there was no change in functional capillary density and only modest increases in cellular damage. We conclude that, in this normotensive pneumonia model of sepsis, NO overproduction was protective of microvascular perfusion in the pancreas.

Animals↗
PubMed2003

Critically ill patients with severe acute respiratory syndrome.

CONTEXT: Severe acute respiratory syndrome (SARS) is a newly recognized infectious disease capable of causing severe respiratory failure. OBJECTIVE: To determine the epidemiological features, course, and outcomes of patients with SARS-related critical illness. DESIGN, SETTING, AND PATIENTS: Retrospective case series of 38 adult patients with SARS-related critical illness admitted to 13 intensive care units (ICUs) in the Toronto area between the onset of the outbreak and April 15, 2003. Data were collected daily during the first 7 days in the ICUs, and patients were followed up for 28 days. MAIN OUTCOME MEASURES: The primary outcome was mortality at 28 days after ICU admission. Secondary outcomes included rate of SARS-related critical illness, number of tertiary care ICUs and staff placed under quarantine, and number of health care workers (HCWs) contracting SARS secondary to ICU-acquired transmission. RESULTS: Of 196 patients with SARS, 38 (19%) became critically ill, 7 (18%) of whom were HCWs. The median (interquartile range [IQR]) age of the 38 patients was 57.4 (39.0-69.6) years. The median (IQR) duration between initial symptoms and admission to the ICU was 8 (5-10) days. Twenty-nine (76%) required mechanical ventilation and 10 of these (34%) experienced barotrauma. Mortality at 28 days was 13 (34%) of 38 patients and for those requiring mechanical ventilation, mortality was 13 (45%) of 29. Six patients (16%) remained mechanically ventilated at 28 days. Two of these patients had died by 8 weeks' follow-up. Patients who died were more often older, had preexisting diabetes mellitus, and on admission to hospital were more likely to have bilateral radiographic infiltrates. Transmission of SARS in 6 study ICUs led to closure of 73 medical-surgical ICU beds. In 2 university ICUs, 164 HCWs were quarantined and 16 (10%) developed SARS. CONCLUSIONS: Critical illness was common among patients with SARS. Affected patients had primarily single-organ respiratory failure, and half of mechanically ventilated patients died. The SARS outbreak greatly strained regional critical care resources.

APACHE↗
PubMed2003

Intermittent flow increases endotoxin-induced adhesion of human erythrocytes to vascular endothelial cells.

OBJECTIVE: To investigate the effects of different conditions of flow on endotoxin induced adhesion of human red blood cells (RBC) to human umbilical vein endothelial cells (HUVEC). DESIGN AND SETTING: Prospective, randomized, controlled in vitro study in a university-affiliated cell biology laboratory. SUBJECTS. Human erythrocytes, human vascular endothelial cells. INTERVENTIONS: Superfusion of HUVEC monolayers with human erythrocytes incubated with either saline (CON) or endotoxin (ETX) with different flow pattern (basic flow rates of 0.65 or 1.3 ml/min; intermittent flow, IMF). The CON/0.6, CON/1.3, CON-IMF/1.3 ( n=7/group) groups served as control, and in test groups ETX/0.6, ETX/1.3, ETX-IMF/0.6, and ETX-IMF/1.3 ( n=7/group) both RBC and HUVECs were incubated with ETX and flow pattern and rates varied. In the IMF experiments flow rates of 0.65 and 1.3 ml/min were combined with stop-and-go flow pattern. MEASUREMENTS AND RESULTS: At continuous flow of 0.65 ml/min erythrocyte adhesion was 61+/-5 cells/mm(2) in CON and 172+/-25 cells/mm(2) after ETX. When flow rate was increased to 1.3 ml/min, adhesion decreased to 27+/-4 cells/mm(2) in CON and 93+/-18 cells/mm(2) after ETX. IMF conditions had no effect on RBC adhesion of naive RBC but increased the number of adhesive erythrocytes after incubation with ETX both at 0.65 ml/min (287+/-33 cells/mm(2)) and at 1.3 ml/min (148+/-13 cells/mm(2)). CONCLUSIONS: RBC adhesion to vascular endothelium is affected by rate and pattern of blood flow. Higher flow rates or shear forces reduce RBC adhesion while stop-and-go flow pattern favored adhesion of ETX-treated erythrocytes to HUVECs. These findings suggest that altered RBCs interact with altered flow patterns potentially contributing to the microcirculatory injury observed in sepsis.

Cell Adhesion↗
PubMed2003

Interhospital variability in satisfaction with withdrawal of life support: room for improvement?

OBJECTIVE: To develop instruments to measure the current level of satisfaction with the withdrawal of life support among nurses and respiratory therapists and to use these instruments to determine whether differences in satisfaction levels with the withdrawal of life support could be found among different institutions. DESIGN: A multicenter, self-administered, questionnaire-based study. SETTING: The intensive care units of three academic and 11 community hospitals. SUBJECTS: A total of 412 critical care nurses and 117 respiratory therapists working in these intensive care units. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: After developing two similar questionnaires for critical care nurses and respiratory therapists, we assessed the reliability of the individual items for each questionnaire and only used those found to be reliable in the analyses. We found variability in the satisfaction level of critical care nurses among different intensive care units and among academic and community hospital intensive care units. Being involved in the plan for withdrawal of life support, comfort with the way discussions with the family had gone, comfort with patient sedation, and increasing experience with withdrawal of life support were items associated with increased nurse satisfaction. For respiratory therapists, there seemed to be similar differences among institutions in satisfaction level, although numbers were limited. Having the physician explain the plan to them and becoming more comfortable with withdrawal of life support as a result of increased experience were found to be associated with increased satisfaction levels for respiratory therapists. CONCLUSIONS: Satisfaction levels of intensive care unit nurses and respiratory therapists with the process of withdrawing life support vary among institutions. This variation may represent an opportunity for improvement in the process of withdrawing life support within this region.

Euthanasia, Passive↗