Early benefit of preserved cognitive function is not sustained at one-year after cardiac surgery: a longitudinal follow-up of the randomized controlled trial.
PURPOSE: Recently, we showed that processing of shed blood with a continuous-flow cell saver during cardiopulmonary bypass resulted in a clinically significant reduction in postoperative cognitive decline (POCD) six weeks after coronary artery bypass graft (CABG) surgery. The current study examined if the early benefit of reduced POCD was sustained in the same patient population at one-year follow-up. METHODS: One hundred seventy patients (cell saver group, n = 84; controls, n = 86) underwent neuropsychological testing at baseline and one year after surgery. The raw scores for each test were converted to Z-scores, and a combined Z-score of ten main variables was then calculated for each study group. RESULTS: Postoperative cognitive decline was present in 16 of 84 (19%) patients in the cell saver group (95% confidence interval [CI], 10.8 to 27.2) vs 15 of 86 (17.4%) patients in the control group (95% CI, 9.6 to 25.2) (P = 0.786). Six of the 15 patients in the control group with POCD at six weeks had the impairment at one year and five did not; four were lost to follow-up. Three of the six cell saver patients with POCD at six weeks still had impairment at one year, two did not, and one was not tested. Thirteen (15.4%) and nine (10.5%) patients in the cell saver and control groups, respectively, developed new POCD which was not evident at the six-week follow-up. CONCLUSIONS: The short-term preservation of cognitive function in elderly patients using the cell saver management strategy did not translate into a long-term benefit one year after CABG surgery. The presence of progressing cerebrovascular disease may be responsible for the long-term cognitive decline. (ClinicalTrials.gov number, NCT00193999).
PMID: 22290354 [PubMed - as supplied by publisher]
Evaluation of TAPSE as a measure of right ventricular output.
Can J Anaesth. 2012 Feb 3;
Authors: Tousignant C, Kim H, Papa F, David Mazer C
Abstract
PURPOSE: This study was designed to show the relationship between tricuspid annular plane systolic excursion (TAPSE) and stroke volume (SV) by thermodilution using three different methods and also to assess whether TAPSE can track hemodynamic changes associated with volume loading and ephedrine administration. METHODS: This was an observational study in 61 elective patients with a pulmonary artery catheter who were undergoing coronary artery bypass graft surgery in a cardiac surgical centre. We measured TAPSE by three methods using transesophageal echocardiography: M mode, speckle tracking at the lateral wall, and tissue tracking at the inferior wall. There were two interventions: leg raising (volume recruitment) or administration of ephedrine 5 mg iv. Echo and hemodynamic measurements were performed before and after each intervention. RESULTS: Eleven patients were excluded due to poor imaging. There were 26 patients in the leg raising group and 24 patients in the ephedrine group. The correlation coefficient between stroke volume (SV) and TAPSE by M mode, speckle tracking, and tissue tracking was 0.48, 0.44, and 0.09, respectively. There was a significant increase in SV following each intervention; however, the changes in TAPSE by any method and velocity were not large enough to reach statistical significance. CONCLUSION: Tricuspid annular plane systolic excursion by M mode and by speckle tracking correlates modestly with SV. There was no correlation between TAPSE and SV by tissue tracking at the inferior wall of the right ventricle. Tricuspid annular plane systolic excursion by M mode and by speckle tracking does not track changes in SV following either volume loading or ephedrine administration.
PMID: 22302303 [PubMed - as supplied by publisher]
A case of drug rash with eosinophilia and systemic symptoms (DRESS) syndrome complicating airway management.
Can J Anaesth. 2012 Jan 20;
Authors: Kumar A, Goldfarb JW, Bittner EA
Abstract
PURPOSE: Drug rash with eosinophilia and systemic symptoms (DRESS) syndrome is a severe multi-system reaction defined by fever, rash, eosinophilia, and internal organ involvement. The condition typically occurs one to eight weeks following exposure to inciting medications. In severe cases, it can develop into multi-organ system failure and death. We present a case of DRESS syndrome with mucosal edema that led to extreme difficulties with airway management. CLINICAL FEATURES: A 65-yr-old male treated for an esophageal perforation with broad-spectrum antibiotics developed fever, eosinophilia, and extensive rash consistent with DRESS syndrome. This condition resulted in a rapid progression to multi-organ system dysfunction, severe hemodynamic instability, and the need for high-dose vasopressors and tracheal intubation. Extensive mucous membrane involvement led to significant complications with airway management and a nearly impossible tracheal intubation, features in the disease not previously described. With the airway secure, initiation of steroids resulted in regression of the disease within 24 hr, resolution of airway edema, and uneventful tracheal extubation a few days later. CONCLUSION: We emphasize the need for early identification of DRESS syndrome as well as the possible airway implications associated with this increasingly recognized clinical entity.
PMID: 22271506 [PubMed - as supplied by publisher]
Plasma methemoglobin as a potential biomarker of anemic stress in humans.
Can J Anaesth. 2012 Jan 20;
Authors: Hare GM, Mu A, Romaschin A, Tsui AK, Shehata N, Beattie WS, Mazer CD
Abstract
PURPOSE: Transfusion of allogeneic red blood cells (RBCs) is one of the main treatments of acute anemia secondary to blood loss and fluid resuscitation within the operating room. Decisions to transfuse blood are based largely on intermediate biological markers (hemoglobin, arterial oxygen saturation, blood pressure, heart rate) which may not accurately reflect inadequacy of tissue oxygen delivery. Based on experimental studies, we hypothesized that anemia-induced tissue hypoxia activates adaptive mechanisms which promote local vascular nitric oxide (NO) production to improve tissue perfusion and survival during acute anemia. Hemoglobin (Hb) oxidation to methemoglobin (MetHb) may be a byproduct of such local NO production. Therefore, we tested the hypothesis that MetHb is a biomarker of hypoxic-anemic stress during acute hemodilution associated with cardiopulmonary bypass. METHODS: With institutional ethics approval, routine laboratory arterial blood gas and co-oximetry values were obtained from 295 patients undergoing heart surgery during February 1 to September 30, 2010, and the values were assessed retrospectively. All samples with an arterial oxygen saturation value ≥90% were included (n = 1,421). The maximal change in Hb associated with hemodilution on cardiopulmonary bypass was determined within 48 hr of surgery (n = 180). A chart review was performed to determine the incidence of RBC transfusion and exogenous nitrate administration. All anonymous data were analyzed by linear regression to determine the relationship between Hb and MetHb. A Wilcoxon Signed Rank Test and Student’s t test were used to determine changes in Hb, MetHb, and carboxyhemoglobin (CarboxHb) levels. All data are presented as mean and significance was assigned at P < 0.05. RESULTS: A significant decrease in Hb [118 (20) g·L(-1) vs 94 (18) g·L(-1)] was associated with an increase in MetHb [0.88 (0.22)% vs 0.95 (0.24)%] (P < 0.001 for both), but not CarboxHb [1.08 (0.47)% vs 1.08 (0.49)%]. Regression analysis revealed a significant relationship between the change in Hb and MetHb (F = 40.3; P < 0.001) but not between the change in Hb and CarboxyHb (F = 0.2; P = 0.694). This correlation was not influenced by RBC transfusion or exogenous nitrate use. CONCLUSIONS: A negative correlation was observed between the change in Hb and MetHb in patients undergoing cardiac surgery and cardiopulmonary bypass. These data support the previously unreported hypothesis that MetHb may be a marker of anemic stress associated with reduced tissue perfusion during acute hemodilution in humans. Further prospective studies are needed to determine if these changes in MetHb are linked to adverse outcomes in patients undergoing cardiac surgery.
PMID: 22271507 [PubMed - as supplied by publisher]
Review article: Medical education research: an overview of methods.
Can J Anaesth. 2012 Jan 4;
Authors: Boet S, Sharma S, Goldman J, Reeves S
Abstract
PURPOSE: This article provides clinician-teachers with an overview of the process necessary to move from an initial idea to the conceptualization and implementation of an empirical study in the field of medical education. This article will allow clinician-teachers to become familiar with educational research methodology in order to a) critically appraise education research studies and apply evidence-based education more effectively to their practice and b) initiate or collaborate in medical education research. SOURCE: This review uses relevant articles published in the fields of medicine, education, psychology, and sociology before October 2011. PRINCIPAL FINDINGS: The focus of the majority of research in medical education has been on reporting outcomes related to participants. There has been less assessment of patient care outcomes, resulting in informing evidence-based education to only a limited extent. This article explains the process necessary to develop a focused and relevant education research question and emphasizes the importance of theory in medical education research. It describes a range of methodologies, including quantitative, qualitative, and mixed methods, and concludes with a discussion of dissemination of research findings. A majority of studies currently use quantitative methods. This article highlights how further use of qualitative methods can provide insight into the nuances and complexities of learning and teaching processes. CONCLUSIONS: Research in medical education requires several successive steps, from formulating the correct research question to deciding the method for dissemination. Each approach has advantages and disadvantages and should be chosen according to the question being asked and the specific goal of the study. Well-conducted education research should allow progression towards the important goal of using evidence-based education in our teaching and institutions.
PMID: 22215522 [PubMed - as supplied by publisher]
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