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Critical Care C ycling to Improve Lower Extremity Strength (CYCLE): protocol for an international, multicentre randomised clinical trial of early in-bed cycling for mechanically ventilated patients. BMJ Open 2023; 13:e075685. [PMID: 37355270 PMCID: PMC10314658 DOI: 10.1136/bmjopen-2023-075685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 06/26/2023] Open
Abstract
INTRODUCTION In-bed leg cycling with critically ill patients is a promising intervention aimed at minimising immobility, thus improving physical function following intensive care unit (ICU) discharge. We previously completed a pilot randomised controlled trial (RCT) which supported the feasibility of a large RCT. In this report, we describe the protocol for an international, multicentre RCT to determine the effectiveness of early in-bed cycling versus routine physiotherapy (PT) in critically ill, mechanically ventilated adults. METHODS AND ANALYSIS We report a parallel group RCT of 360 patients in 17 medical-surgical ICUs and three countries. We include adults (≥18 years old), who could ambulate independently before their critical illness (with or without a gait aid), ≤4 days of invasive mechanical ventilation and ≤7 days ICU length of stay, and an expected additional 2-day ICU stay, and who do not fulfil any of the exclusion criteria. After obtaining informed consent, patients are randomised using a web-based, centralised system to either 30 min of in-bed cycling in addition to routine PT, 5 days per week, up to 28 days maximum, or routine PT alone. The primary outcome is the Physical Function ICU Test-scored (PFIT-s) at 3 days post-ICU discharge measured by assessors blinded to treatment allocation. Participants, ICU clinicians and research coordinators are not blinded to group assignment. Our sample size estimate was based on the identification of a 1-point mean difference in PFIT-s between groups. ETHICS AND DISSEMINATION Critical Care Cycling to improve Lower Extremity (CYCLE) is approved by the Research Ethics Boards of all participating centres and Clinical Trials Ontario (Project 1345). We will disseminate trial results through publications and conference presentations. TRIAL REGISTRATION NUMBER NCT03471247 (Full RCT); NCT02377830 (CYCLE Vanguard 46 patient internal pilot).
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Age alters cardiac autonomic modulations during and following exercise-induced heat stress in females. Temperature (Austin) 2018; 5:184-196. [PMID: 30377635 DOI: 10.1080/23328940.2018.1432918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 01/26/2018] [Accepted: 02/07/2018] [Indexed: 12/19/2022] Open
Abstract
The aim of this study was to examine the effect of natural ageing on heart rate variability during and following exercise-induced heat stress in females. Eleven young (∼24 years) and 13 older (∼51 years), habitually active females completed an experimental session consisting of baseline rest, moderate intensity intermittent exercise (four 15-min bouts separated by 15-min recovery) and 1-hour of final recovery in a hot and dry (35°C, 20% relative humidity) environment. Respiratory and heart rate recordings were continuously logged with 10-min periods analysed at the end of: baseline rest; each of the exercise and recovery bouts; and during the 1-hour final recovery period. Comparisons over time during exercise and recovery, and between groups were conducted via two-way repeated-measures ANCOVAs with rest values as the covariate. During baseline rest, older females exhibited lower heart rate variability compared to young females with similar levels of respiration and most (∼71-79%) heart rate variability measures during repeated exercise and recovery. However, older females exhibited heart rate variability metrics suggestive of greater parasympathetic modulation (greater long axis of Poincare plot, cardiac vagal index; lower low-high frequency ratio) during repeated exercise with lower indices during the latter stage of prolonged recovery (less very low frequency component, Largest Lyapunov Exponent; greater cardiac sympathetic index). The current study documented several unique, age-dependent differences in heart rate variability, independent of respiration, during and following exercise-induced heat stress for females that may assist in the detection of normal heat-induced adaptations as well as individuals vulnerable to heat stress.
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Impact of surgical approach on perioperative and long-term outcomes following esophagectomy for esophageal cancer. Surg Endosc 2017; 32:1892-1900. [PMID: 29067584 DOI: 10.1007/s00464-017-5881-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 09/13/2017] [Indexed: 01/07/2023]
Abstract
BACKGROUND Surgical resection remains a critical component of esophageal cancer treatment with curative-intent. The aim of this study was to compare open (OE) to minimally invasive Ivor Lewis esophagectomy (MIE) with respect to perioperative and oncologic outcomes. METHODS Retrospective single-institution review of MIE and OE patients operated between 2001 and 2015 was conducted. Univariable and multivariable models were created using Cox regression. The Kaplan-Meier method was used to compare oncologic outcomes. Propensity score matching was used to compare oncological outcomes in MIE and OE patients. RESULTS Of 210 esophageal resection patients, 47% had OE (137/291) and 25% had MIE (73/291). The MIE and OE groups were comparable with respect to patient factors and operative details. Fewer OE patients received neoadjuvant chemoradiation. MIE was associated with improved lymph node yield, (MIE = 30 [IQR:22-39]; OE = 14 [IQR:7-19], p < 0.001), less intraoperative blood loss (MIE = 312 mL [100-400]; OE = 657 mL [350-700], p < 0.001), and shorter median length of stay (MIE = 10 days [IQR = 8-14]; OE = 14 days [IQR = 11-22] p < 0.01). The OE group had significantly more adverse events resulting in reoperation or intensive care unit admission (MIE = 21%; OE = 34%; p < 0.01). On multivariable analysis, age and positive resection margins were associated with decreased odds of survival. The number of lymph nodes retrieved, positive resection margins, and pathologic stage were significant predictors of disease-free survival. Analysis of 69 matched pairs showed equivalent median overall survival (MIE = 49 months [18-67]; OE = 29 months [17-69]; p = 0.26) and disease-free survival (MIE = 9 [6-22]; OE = 13 [6-22]; p = 0.45) between the two groups. CONCLUSIONS Although long-term oncologic outcomes appear to be similar, MIE is associated with significantly less intraoperative blood loss, improved lymph node yield, less risk of severe postoperative adverse events, and shorter length of stay.
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Reply. Ann Thorac Surg 2017; 104:724. [PMID: 28734423 DOI: 10.1016/j.athoracsur.2016.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 11/08/2016] [Indexed: 10/19/2022]
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Adjuvant sunitinib following chemoradiotherapy and surgery for locally advanced esophageal cancer: a phase II trial. Dis Esophagus 2016; 29:1152-1158. [PMID: 26663741 DOI: 10.1111/dote.12444] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The prognosis for locally advanced esophageal cancer is poor despite the use of trimodality therapy. In this phase II study, we report the feasibility, tolerability and efficacy of adjuvant sunitinib. Included were patients with stage IIa, IIB or III cancer of the thoracic esophagus or gastroesophageal junction. Neoadjuvant therapy involved Irinotecan (65 mg/m2 ) + Cisplatin (30 mg/m2 ) on weeks 1 and 2, 4 and 5, 7 and 8 with concurrent radiation (50Gy/25 fractions) on weeks 4-8. Sunitinib was commenced 4-13 weeks after surgery and continued for one year. Sixty-one patients were included in the final analysis, 36 patients commenced adjuvant sunitinib. Fourteen patients discontinued sunitinib due to disease recurrence (39%) within the 12-month period, 12 (33%) discontinued due to toxicity, and 3 (8%) requested cessation of therapy. In the overall population, median survival was 26 months with a 2 and 3-year survival rate of 52% and 35%, respectively. The median survival for the 36 patients treated with sunitinib was 35 months and 2-year survival probability of 68%. In a historical control, a prior phase II study with the same trimodality therapy (n = 43), median survival was 36 months, with a 2-year survival of 67%. Initiation of adjuvant sunitinib is feasible, but poorly tolerated, with no signal of additional benefit over trimodality therapy for locally advanced esophageal cancer.
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Heart rate variability during exertional heat stress: effects of heat production and treatment. Eur J Appl Physiol 2014; 114:785-92. [PMID: 24390688 DOI: 10.1007/s00421-013-2804-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 12/16/2013] [Indexed: 11/29/2022]
Abstract
PURPOSE We assessed the efficacy of different treatments (i.e., treatment with ice water immersion vs. natural recovery) and the effect of exercise intensities (i.e., low vs. high) for restoring heart rate variability (HRV) indices during recovery from exertional heat stress (EHS). METHODS Nine healthy adults (26 ± 3 years, 174.2 ± 3.8 cm, 74.6 ± 4.3 kg, 17.9 ± 2.8 % body fat, 57 ± 2 mL·kg·(-1) min(-1) peak oxygen uptake) completed four EHS sessions incorporating either walking (4.0-4.5 km·h(-1), 2 % incline) or jogging (~7.0 km·h(-1), 2 % incline) on a treadmill in a hot-dry environment (40 °C, 20-30 % relative humidity) while wearing a non-permeable rain poncho for a slow or fast rate of rectal temperature (T re) increase, respectively. Upon reaching a T re of 39.5 °C, participants recovered until T re returned to 38 °C either passively or with whole-body immersion in 2 °C water. A comprehensive panel of 93 HRV measures were computed from the time, frequency, time-frequency, scale-invariant, entropy and non-linear domains. RESULTS Exertional heat stress significantly affected 60/93 HRV measures analysed. Analyses during recovery demonstrated that there were no significant differences between HRV measures that had been influenced by EHS at the end of passive recovery vs. whole-body cooling treatment (p > 0.05). Nevertheless, the cooling treatment required statistically significantly less time to reduce T re (p < 0.001). CONCLUSIONS While EHS has a marked effect on autonomic nervous system modulation and whole-body immersion in 2 °C water results in faster cooling, there were no observed differences in restoration of autonomic heart rate modulation as measured by HRV indices with whole-body cold-water immersion compared to passive recovery in thermoneutral conditions.
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Sampling rate of heart rate variability impacts the ability to detect acidemia in ovine fetuses near-term. Front Pediatr 2014; 2:38. [PMID: 24829897 PMCID: PMC4017161 DOI: 10.3389/fped.2014.00038] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 04/18/2014] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND To evaluate the impact of sampling rate on the predictive capability of continuous fetal heart rate (FHR) variability (fHRV) monitoring for detecting fetal acidemia during labor, we tested the performance of the root mean square of successive differences (RMSSD) in R-R intervals from the ECG when acquired with the sampling rate of 4 Hz currently available in FHR monitors, in comparison to the gold standard of 1000 Hz. METHODS Near-term ovine fetuses (N = 9) were chronically prepared with precordial electrodes for recording ECG, vascular catheters for blood sampling, and an umbilical cord occluder. For 1 min every 2.5 min, animals underwent mild partial umbilical cord occlusions (UCO) × 1 h, moderate partial UCO × 1 h, then complete UCO × 2 h, or until arterial pH reached <7.00. Arterial blood samples were drawn at baseline and every 20 min during the UCO series. RMSSD was calculated continuously in 5 min windows using an automated, standardized system (CIMVA.com). RESULTS are presented as mean ± SEM with significance assumed for p < 0.05. RESULTS Repetitive UCO resulted in pH decreasing from 7.35 ± 0.01 to 7.00 ± 0.03. In all nine animals, RMSSD increased from 16.7 ± 1.0 ms at baseline to 44.4 ± 2.3 ms, 70 ± 15 min prior to reaching the pH nadir when sampled at 1000 Hz. When sampled at 4 Hz, RMSSD at baseline measured 36.1 ± 6.0 ms and showed no significant increase during the UCO series until the pH nadir was reached. Consequently, early detection of severe hypoxic-acidemia would have been missed in all fetuses. CONCLUSION RMSSD as a measure of fHRV when calculated from FHR sampled at 1000 Hz allowed for the early detection of worsening hypoxic-acidemia in each fetus. However, when calculated at the low sampling rate of 4 Hz used clinically, RMSSD remained unchanged until terminally when the nadir pH was reached. For early detection of fetal acidemia during labor, more sensitive means of acquiring FHR are therefore recommended than currently deployed, e.g., trans-abdominal fetal ECG.
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Predicting Lymph Node Metastases in Early Esophageal Adenocarcinoma Using a Simple Scoring System. J Am Coll Surg 2013; 217:191-9. [DOI: 10.1016/j.jamcollsurg.2013.03.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 03/21/2013] [Accepted: 03/21/2013] [Indexed: 02/08/2023]
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Comparison of heart and respiratory rate variability measures using an intermittent incremental submaximal exercise model. Appl Physiol Nutr Metab 2013; 38:1128-36. [PMID: 24053520 DOI: 10.1139/apnm-2012-0370] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To better understand the alterations in cardiorespiratory variability during exercise, the present study characterized the patterns of change in heart rate variability (HRV), respiratory rate variability (RRV), and combined cardiorespiratory variability (HRV-RRV) during an intermittent incremental submaximal exercise model. Six males and six females completed a submaximal exercise protocol consisting of an initial baseline resting period followed by three 10-min bouts of exercise at 20%, 40%, and 60% of maximal aerobic capacity (V̇O2max). The R-R interval and interbreath interval variability were measured at baseline rest and throughout the submaximal exercise. A group of 93 HRV, 83 RRV, and 28 HRV-RRV measures of variability were tracked over time through a windowed analysis using a 5-min window size and 30-s window step. A total of 91 HRV measures were able to detect the presence of exercise, whereas only 46 RRV and 3 HRV-RRV measures were able to detect the same stimulus. Moreover, there was a loss of overall HRV and RRV, loss of complexity of HRV and RRV, and loss of parasympathetic modulation of HRV (up to 40% V̇O2max) with exercise. Conflicting changes in scale-invariant structure of HRV and RRV with increases in exercise intensity were also observed. In summary, in this simultaneous evaluation of HRV and RRV, we found more consistent changes across HRV metrics compared with RRV and HRV-RRV.
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Embracing the certainty of uncertainty: implications for health care and research. PERSPECTIVES IN BIOLOGY AND MEDICINE 2013; 56:65-77. [PMID: 23748527 DOI: 10.1353/pbm.2013.0009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
"Uncertainty" is the ongoing realization that we cannot predict the future, and "surprise" reminds us lest we forget. Despite the fact that uncertainty is an undeniable fact of everyday experiences, in particular when providing care to patients, it is ignored and under-evaluated scientifically. Understandably and appropriately, medical science seeks knowledge, certainty, and prediction; however, the fundamental truth of intrinsic irreducible uncertainty remains neglected. The principal hypothesis of this article is that greater acceptance and understanding of intrinsic uncertainty offers valuable insights towards improving the delivery and management of health care, as well as the performance of clinical and basic science research. This review highlights the ubiquitous presence and acceptance of irreducible uncertainty in diverse domains of science, defines and classifies uncertainty arising from this awareness, and explores the insights and implications of this understanding with regard to health-care practice, health-care management, physician-patient communication, basic science research, and clinical research. It offers specific recommendations in each area of focus that are proposed to stimulate deliberation and investigation.
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Impact of patient selection, disease progression, and adverse events on esophageal cancer outcomes after trimodality therapy. Ann Thorac Surg 2012; 94:1659-66. [PMID: 22981444 DOI: 10.1016/j.athoracsur.2012.05.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 05/08/2012] [Accepted: 05/11/2012] [Indexed: 12/17/2022]
Abstract
BACKGROUND Neoadjuvant chemoradiation followed by surgery (NeoCRT) has been advocated as standard therapy for resectable esophageal cancer. Our objective was to compare oncologic outcomes between NeoCRT and upfront surgical resection (SURG). METHODS We conducted a single-institution, retrospective review of all potentially resectable esophageal cancer patients treated with NeoCRT or SURG. RESULTS From 2003 to 2010, 151 patients had NeoCRT (n = 48; 31.8%) or SURG (n = 103; 68.1%). Histology was mostly adenocarcinoma (77.5%) or squamous carcinoma (19.2%). Mean radiation dose was 44 ± 0.1 Gy, and 80.8% received platinum-based doublet chemotherapy. There were more women in the SURG group (23.3% vs 4.2%; p < 0.01) and more cardiovascular comorbidity in the NeoCRT group (39.6% vs 21.4%; p = 0.027). There was no difference in age, histology, R0 resection rate, and treatment-related mortality (NeoCRT = 4.2%; SURG = 3.9%; p = 0.15). Failure to undergo resection after NeoCRT (n = 11; 22.9%) was mainly due to disease progression (n = 6) or treatment-related mortality (n = 4). Resection could not be performed in 4 SURG patients (3.9%; p < 0.001; unresectable = 2; occult metastases = 2). NeoCRT did not improve median survival (NeoCRT = 29 ± 6; SURG = 26 ± 3 months; p = 0.376) or recurrence-free interval (NeoCRT = 25.8 ± 5; SURG = 19.4 ± 2 months; p = 0.19). Complete pathologic response (n = 8; 21.6%) was not associated with improved survival. If we exclude from analysis NeoCRT patients who did not undergo surgery, survival was significantly improved after NeoCRT (NeoCRT = 41 ± 15; SURG = 24 ± 8 months; p = 0.0082). CONCLUSIONS Patient selection and early assessment of treatment response may be key factors in identifying the best candidates for trimodality therapy.
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Cardiovascular and Thermal Responses to Repeated Head-Up Tilts Following Exercise-Induced Heat Stress. ACTA ACUST UNITED AC 2010; 81:646-53. [DOI: 10.3357/asem.2733.2010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Hemorrhagic shock resuscitation with a low molecular weight starch reduces neutrophil-endothelial interactions and vessel leakage in vivo. Surg Infect (Larchmt) 2003; 2:275-87; discussion 287-8. [PMID: 12593703 DOI: 10.1089/10962960152813313] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The polymorphonuclear neutrophil (PMN) has been implicated in the pathogenesis of endothelial cell (EC) damage and organ injury following hemorrhagic shock. Pentastarch (PTS), a low substituted medium molecular weight (MW) colloid, improves hemodynamics in hypovolemic shock and cardiac surgery. No data exist comparing the immunomodulation of PTS and Ringer's lactate (RL) on the activation of PMN in hemorrhagic shock in vivo. METHODS Using an in vivo murine hemorrhagic shock model (blood withdrawal to maintain 50 mmHg x 45 min), circulating PMN were observed every 15 minutes using intravital microscopy on cremaster muscle. EC-PMN interactions (videorecorded and subsequently analyzed blindly), vessel leakage (live epifluorescence after injection of 50 mg/kg fluorescent albumin) and PMN expression of L-selectin (immunofluorescent monoclonal antibodies and flow cytometry) were evaluated in three resuscitation groups: PTS (7.14 mL/kg 10% pentastarch/0.9% NaCl + shed blood, n = 13), RL (RL [2 x shed blood volume] + shed blood, n = 13) and SHAM (0 hemorrhage, 0 resuscitation, n = 9). Significance was evaluated by ANOVA with Bonferroni correction. RESULTS PMN rolling was significantly diminished in PTS and SHAM as compared to RL animals at all time points. Similar differences were found in PMN adherence to EC at most time points onwards from 15 minutes following resuscitation. In vivo vessel permeability was lowest in SHAM and PTS animals (mean 0.274 +/- 0.07 and 0.356 +/- 0.15, respectively, p > 0.05) and highest in RL animals (0.667 +/- 0.09, p < 0.001 vs PTS or SHAM). PMN L-selectin expression tended to be higher in the RL group than either SHAM and PTS groups. There were no flow-mechanics differences between groups (vessel diameter, mean red cell velocity, shear stress, shear rate). CONCLUSIONS 10% pentastarch reduces RL-associated EC-PMN interactions and vessel leakage following hemorrhagic shock. These results support the use of low MW starches to resuscitate hemorrhagic shock, potentially reducing PMN-mediated tissue injury.
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Decreased systemic polymorphonuclear neutrophil (PMN) rolling without increased PMN adhesion in peritonitis at remote sites. ARCHIVES OF SURGERY (CHICAGO, ILL. : 1960) 2000; 135:959-66. [PMID: 10922259 DOI: 10.1001/archsurg.135.8.959] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Previous in vitro studies have demonstrated that the host response to intra-abdominal infection produces increased generalized polymorphonuclear neutrophil (PMN) adherence to vascular endothelial cells (ECs), which may lead to subsequent endothelial damage, leaky capillaries, and organ dysfunction. There are scant data to demonstrate this enhanced systemic PMN adherence in vivo or the influence of PMN rolling on PMN endothelial adherence. HYPOTHESIS Systemic PMN adherence in the animal with sepsis is increased. DESIGN In vivo murine model of a 2-front infection using intravital microscopy of the cremasteric muscle to quantify PMN-EC adherence in a septic response. SETTING Basic science laboratory and animal surgical facility. PATIENTS OR OTHER PARTICIPANTS One hundred CD1 male mice. INTERVENTIONS Animals underwent cecal ligation and puncture peritonitis, cremasteric muscle Escherichia coli infection, both infections, or neither (controls). Eighteen hours later, the mice underwent exteriorization of the cremasteric muscle under an intravital microscope for measurement of PMN-EC interactions. Blood was then drawn for calculation of circulating PMN counts. MAIN OUTCOME MEASURES Adherence of PMNs, PMN rolling flux, PMN rolling velocity, and circulating PMN counts. RESULTS Circulatory mechanics did not differ between the groups. Unlike static in vitro systems, we could not detect an increase in PMN adherence after peritonitis with this dynamic in vivo model. A local (cremasteric) infection was associated with marked PMN adherence. Peritonitis was associated with reduced PMN adherence at a local infection site as well as reduced rolling adhesion and PMN rolling velocity. CONCLUSIONS The data suggest that intra-abdominal infection does not increase remote PMN adherence, and may actually result in reduction of systemic adherence via modulation of PMN rolling.
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Abstract
OBJECTIVES The objectives of this article are to introduce and explore a novel paradigm based on complex nonlinear systems, and to evaluate its application to critical care research regarding the systemic host response and multiple organ dysfunction syndrome (MODS). DATA SOURCES Published original work, review articles, scientific abstracts and books, as well as our personal files. STUDY SELECTION Studies were selected for their relevance to the applications of nonlinear complex systems, to critical care medicine, and to the concepts presented. DATA EXTRACTION We extracted all applicable data. DATA SYNTHESIS Following a brief review of MODS, an introduction to complex nonlinear systems is presented, including clear concepts, definitions, and properties. By examining the multiple, nonlinear, interrelated, and variable interactions between the metabolic, neural, endocrine, immune, and inflammatory systems; data regarding interconnected antibody networks; and the redundant, nonlinear, interdependent nature of the inflammatory response, we present the hypothesis that the systemic host response to trauma, shock, or sepsis must be evaluated as a complex nonlinear system. This model provides a new explanation for the failure of trials using various antimediator therapies in the treatment of patients with sepsis and MODS. Understanding the host response as a complex nonlinear system offers innovative means of studying critical care patients, specifically by suggesting a greater focus on systemic properties. We hypothesize that analysis of variability and connectivity of individual variables offer a novel means of evaluating and differentiating the systemic properties of a complex nonlinear system. Current applications of evaluating variability and connectivity are discussed, and insights regarding future research are offered. CONCLUSION The paradigm offered by the study of complex nonlinear systems suggests new insights to pursue research to evaluate, monitor, and treat patients with MODS.
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Polymorphonuclear neutrophil (PMN) recruitment in a 2-front murine injury model: triage of PMNs to competing stimuli of recruitment. Surgery 2000; 127:323-8. [PMID: 10715989 DOI: 10.1067/msy.2000.103497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Intensive care unit patients as a group have the highest rate of nosocomial infections, such as pneumonia, urinary tract infections, and wound infections. The triage of polymorphonuclear neutrophils (PMNs) during an acute inflammatory response was investigated to determine if the severity of injury or infection contributes to PMN delivery. METHODS A murine cecal ligation and puncture-induced peritonitis model with polyvinyl sponge discs were used to collect the PMNs in the abdomen (primary site) and in the subcutaneous tissue of the dorsum (remote site). Eighty CD1 male mice--20 in each of 4 groups--were assigned to the following: cecal ligation and puncture (CLP), sham laparotomy with cecal manipulation (CM), polyvinyl sponge placement in the abdomen and back only (SP), and sponge placement in the back alone (CON [control]). After 24 hours, the sponges were harvested, and the PMNs were collected and counted on a hemocytometer. RESULTS These data, reported as mean PMN cells x 10(5) +/- SEM, demonstrated that back sponges contained significantly fewer PMNs in the CLP group (3.29 +/- 1.1) than in the CM group (7.77 +/- 1.61, P = .04), the SP group (8.69 +/- 1.67, P = .01), and the CON group (11.04 +/- 1.91, P < .001). CONCLUSIONS These results demonstrate that PMN delivery to sites of secondary injury are inversely correlated to the severity of the primary injury or peritonitis.
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Abstract
BACKGROUND There have been no attempts to objectively compare resident teaching ability with resident knowledge level. METHODS Resident teaching ability, as rated by medical students and junior surgical residents, was compared with resident knowledge level, estimated by in-training examination results, for 18 PGY5 and PGY4 surgical residents at McGill University (September 1996 to July 1997). RESULTS There was a trend to suggest that greater teaching ability is associated with higher in-training examination scores; this did not achieve statistical significance. PGY4 residents were rated as better teachers than PGY5 residents. Resident self-evaluation revealed a high degree of interest in teaching; inadequate time was the principal deterrent to resident teaching; enjoyment and learning during teaching were found to be the most common incentives. CONCLUSIONS Our results suggest an association between resident level of knowledge and teaching ability. The principal deterrent to teaching--inadequate time--must be addressed to effectively assist surgical resident teaching.
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Reduction in neutrophil cell surface expression of tumor necrosis factor receptors but not Fas after transmigration: implications for the regulation of neutrophil apoptosis. ARCHIVES OF SURGERY (CHICAGO, ILL. : 1960) 1998; 133:1305-10. [PMID: 9865647 DOI: 10.1001/archsurg.133.12.1305] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVES To test the hypothesis that loss of polymorphonuclear neutrophil tumor necrosis factor alpha (TNF-alpha) receptors during transmigration renders the exudate neutrophil refractory to TNF-alpha-mediated stimulation of apoptosis; and to investigate the surface expression of Fas on both circulating and exudate neutrophils. DESIGN A prospective cohort study. SETTING Surgical laboratory of a tertiary care hospital. PARTICIPANTS Twenty-one healthy human volunteers. INTERVENTIONS All subjects had circulating neutrophils and exudate neutrophils collected by venipuncture and skin window methods, respectively. MAIN OUTCOME MEASURES Circulating and exudate neutrophils were incubated in culture medium (1.0x10(6) neutrophils per milliliter) alone or with TNF-alpha (100 ng/mL). Apoptosis was evaluated by flow cytometry (annexin V-fluorescein isothiocyanate and propidium iodide). Tumor necrosis factor alpha-phycoerythrin and anti-human Fas-fluorescein isothiocyanate were used to evaluate neutrophil TNF-alpha receptors and surface expression of Fas. RESULTS Exudate neutrophils had a significant delay in apoptosis rates when compared with circulating neutrophils. The percentage of neutrophils expressing TNF-alpha receptors was significantly diminished after exudation (80%+/-15% vs 33%+/-9%; P<.001), as was the median channel number of TNF-alpha phycoerythrin fluorescence (8.1+/-1.6 vs 5.2+/-0.5; P=.001). However, the expression of Fas was unchanged after transmigration (percentage positive for Fas: 98.7%+/-0.7% vs 92.8%+/-3.4%, P=.89; Fas antibody-fluorescein isothiocyanate median channel fluorescence: 12.2+/-1.1 vs 13.1+/-1.2; P=.80). Exposure of exudate neutrophils to TNF-alpha failed to increase their rate of apoptosis. CONCLUSIONS Exudate polymorphonuclear neutrophils are confirmed to have delayed apoptosis. Loss of TNF-alpha receptors during transmigration is necessary for neutrophil survival in the extravascular inflammatory milieu.
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