A community-based pharmacist-led smoking cessation program, before elective total joint replacement surgery, markedly enhances smoking cessation rates.

INTRODUCTION: We compared smoking cessation outcomes between those who used a pharmacist-led community-based smoking cessation intervention and those who did not, prior to total joint replacement (TJR) surgery. Also, we examined intervention characteristics (e.g. number/duration of sessions attended, recommended therapy) and smoking cessation outcomes. METHODS: This prospective evaluation was nested within a comparative study from a centralized clinic that prepares over 3000 patients annually for TJR and focused on participants referred to the community-based smoking cessation program preoperatively. Pharmacists offered an individualized evidence-based intervention and collected visit, duration and intervention data. Smoking cessation, the primary outcome, was ascertained independently of participating pharmacists at 6 weeks post-operative using exhaled CO monitoring and at 6 months post-recruitment via telephone interview. RESULTS: Of 286 eligible candidates, 104 agreed to participate, with one subsequently withdrawing (n=103). At 6 weeks post-operatively, 66/103 (64%) participants returned for study re-assessment while 63/103 (61%) participants completed the post-recruitment interview at 6 months; non-respondents to study follow-up were considered smokers. Of 103 participants, 58 (56%) consulted with a pharmacist; those who did not consult a pharmacist (n=45) were slightly younger (p=0.02) with significantly higher CO level (p=0.02) on study entry. Validated 7-day point prevalence abstinence (PPA) at 6 weeks post-operative was 11/58 (19%) in pharmacist-compliant participants compared to 2/45 (4%) in non-compliant participants (p=0.04). At 6 months post-recruitment, 19/58 (33%) pharmacistcompliant participants self-reported a 7-day PPA compared to 2/45 (4%) by non-compliant participants (p<0.001). For pharmacist-compliant participants, 33/58 (54%) saw the pharmacist 4 times; the mean overall pharmacist time was 71.8±24.4 minutes/patient with 26/58 (45%) and 19/58 (33%) prescribed nicotine replacement therapy and varenicline, respectively, and 13/58 (22%) not using medication; post hoc analysis suggested varenicline was marginally more effective for smoking cessation than no medication (p=0.04). CONCLUSIONS: Community-based pharmacist-led smoking cessation programs are an effective addition to usual preoperative care for smokers awaiting elective TJR. Using existing community resources led to higher smoking cessation rates in smokers waiting for TJR relative to those not using these resources.

Society for Perioperative Assessment and Quality Improvement (SPAQI) Consensus Statement on Perioperative Smoking Cessation.

Smokers are at increased risk for surgical complications. Despite the known benefits of smoking cessation, many perioperative health care providers do not routinely provide smoking cessation interventions. The variation in delivery of perioperative smoking cessation interventions may be due to limited high-level evidence for whether smoking cessation interventions used in the general population are effective and feasible in the surgical population, as well as the challenges and barriers to implementation of interventions. Yet smoking is a potentially modifiable risk factor for improving short- and long-term patient outcomes. The purpose of the Society for Perioperative Assessment and Quality Improvement (SPAQI) Consensus Statement on Perioperative Smoking Cessation is to present recommendations based on current scientific evidence in surgical patients. These statements address questions regarding the timing and intensity of interventions, roles of perioperative health care providers, and behavioral and pharmacological interventions. Barriers and strategies to overcome challenges surrounding implementation of interventions and future areas of research are identified. These statements are based on the current state of knowledge and its interpretation by a multidisciplinary group of experts at the time of publication.

Impact of a standardized referral to a community pharmacist-led smoking cessation program before elective joint replacement surgery.

INTRODUCTION: Smokers undergoing total joint replacement (TJR) are more likely to develop infections and be re-admitted than non-smokers. The primary purpose of this study was to evaluate the effectiveness of standardized preoperative referral to a community-based pharmacist-led smoking cessation program compared to usual care for patients undergoing TJR. Secondarily, we evaluated the use of the smoking cessation program. METHODS: A pre-post quasi-experimental study was conducted at a central intake clinic that prepares approximately 3000 TJR patients annually. Participants were recruited at a mean of 13±11.1 weeks preoperatively and provided informed consent. Participants in the 'pre' observational phase (OP) received usual care for smoking cessation. For 'post' intervention phase (IP) participants, a referral was sent to a community-based pharmacist-led smoking cessation program. Smoking status was validated on study entry using exhaled carbon monoxide. Participants' smoking status was re-assessed using self-reported point prevalence abstinence at 6 months post-recruitment. RESULTS: We enrolled 120/150 (80%) potential OP candidates and 104/286 (36%) potential IP candidates. The groups were similar on study entry; overall, the mean age of participants was 58.7±9.1 years and 103 (47%) were male. They reported medium nicotine dependence with 37±11.6 mean years smoked. At 6 months post-recruitment, 8 (7%) OP participants self-reported 30-day point prevalence abstinence compared to 21 (20%) IP participants (p=0.003). Only 58 (56%) IP participants complied with the pharmacist referral, with 19 (33%) of those seeing the pharmacist reporting point prevalence abstinence at 6 months compared to only 2 (4%) of the 45 participants who did not see the pharmacist (p<0.001). CONCLUSIONS: Referral to a community smoking cessation program as preoperative standard of care is feasible and can enhance long-term quit rates, but voluntary participation led to low recruitment to the program.

Tapered vs. Uniform Tube-Load Modeling of Blood Pressure Wave Propagation in Human Aorta.

In this paper, tapered vs. uniform tube-load models are comparatively investigated as mathematical representation for blood pressure (BP) wave propagation in human aorta. The relationship between the aortic inlet and outlet BP waves was formulated based on the exponentially tapered and uniform tube-load models. Then, the validity of the two tube-load models was comparatively investigated by fitting them to the experimental aortic and femoral BP waveform signals collected from 13 coronary artery bypass graft surgery patients. The two tube-load models showed comparable goodness of fit: (i) the root-mean-squared error (RMSE) was 3.3+/-1.1 mmHg in the tapered tube-load model and 3.4+/-1.1 mmHg in the uniform tube-load model; and (ii) the correlation was r = 0.98+/-0.02 in the tapered tube-load model and r = 0.98+/-0.01 mmHg in the uniform tube-load model. They also exhibited frequency responses comparable to the non-parametric frequency response derived from the aortic and femoral BP waveforms in most patients. Hence, the uniform tube-load model was superior to its tapered counterpart in terms of the Akaike Information Criterion (AIC). In general, the tapered tube-load model yielded the degree of tapering smaller than what is physiologically relevant: the aortic inlet-outlet radius ratio was estimated as 1.5 on the average, which was smaller than the anatomically plausible typical radius ratio of 3.5 between the ascending aorta and femoral artery. When the tapering ratio was restricted to the vicinity of the anatomically plausible typical value, the exponentially tapered tube-load model tended to underperform the uniform tube-load model (RMSE: 3.9+/-1.1 mmHg; r = 0.97+/-0.02). It was concluded that the uniform tube-load model may be more robust and thus preferred as the representation for BP wave propagation in human aorta; compared to the uniform tube-load model, the exponentially tapered tube-load model may not provide valid physiological insight on the aortic tapering, and its efficacy on the goodness of fit may be only marginal.

Nicotine addiction management following surgery: a quality improvement approach in the post anesthesia care unit.

QUALITY PROBLEM: For smokers, hospital admission is accompanied by forced involuntary nicotine abstinence due to smoke-free site/grounds policies. An audit of patients admitted to our surgical wards revealed that identification of smoking status was inadequate and that nicotine addiction management (NAM) was infrequently offered. The project aimed to enhance both these metrics by initiating NAM in the post anesthesia care unit (PACU). INITIAL ASSESSMENT: Out of 744 patients admitted to our PACU in August 2015, 54% had their smoking status documented. The 200 patients (27%) out of the 744 were smokers and only 50% were offered NAM before discharge. CHOICE OF SOLUTION: PACU unit staff to determine the smoking status of every patient before discharge from the PACU (later changed to OR nursing staff) and, if a patient was identified as a smoker, to offer NRT (patch and mouth spray only) and initiate therapy prior to transfer of the patient to the ward. IMPLEMENTATION: Data about number of patients admitted, presence of documented smoking status, number of identified smokers, and number offered/accepted nicotine replacement therapy (NRT) were collected at baseline and thereafter quarterly. Engaging video education sessions addressed the education gaps highlighted in a needs assessment. Identification of smoking status was made part of preoperative checklist and NRT was made available in post-operative recovery room. RESULTS: These interventions resulted in an increase in screening for tobacco use from 54% at baseline to 95% and the offer of NRT to smokers from 50 to 89%.

Assessing the accuracy of algorithm-derived cardiorespiratory fitness in surgical patients: a prospective cohort study.

PURPOSE: To determine if a non-exercise algorithm-derived assessment of cardiorespiratory fitness (CRFA) accurately predicted estimated values obtained using a six-minute walk test (CRF6MWD) and the Duke Activity Status Index (CRFDASI). METHODS: Following research ethics board approval, an observational cohort study was conducted in selected, consenting patients undergoing elective surgery. Participants completed questionnaires assessing their self-reported exercise capacity. Their height, weight, waist circumference, and vital signs were measured. A six-minute walk test was performed twice with a 45-min rest interval between tests. The correlation between CRFA and both CRF6MWD and CRFDASI was determined. RESULTS: Two hundred forty-two participants were included. Mean age was 62 (range 45-88 yr); 150 (62%) were male, 87 (36%) self-reported walking or jogging > 16 km per week, and 49 (20%) were current smokers. The CRFA and CRF6MWD were highly correlated (Pearson r = 0.878; P < 0.001). CRFA and CRFDASI were less strongly correlated (Pearson r = 0.252; P < 0.001). Among patients capable of walking > 427 m in the six-minute walk test, CRFA, CRF6MWD, and CRFDASI were equivalent. CONCLUSION: A non-exercise algorithm can estimate cardiorespiratory fitness in patients presenting for elective surgery. The variables required to compute CRFA can be obtained in a clinic setting without the need to engage in formal exercise testing. Further evaluation of CRFA as a predictor of long-term outcome in patients is warranted.

A multicentre randomized-controlled trial of inhaled milrinone in high-risk cardiac surgical patients.

PURPOSE: Inhaled milrinone (iMil) has been used for the treatment of pulmonary hypertension (PH) but its efficacy, safety, and prophylactic effects in facilitating separation from cardiopulmonary bypass (CPB) and preventing right ventricular (RV) dysfunction have not yet been evaluated in a clinical trial. The purpose of this study was to investigate if iMil administered before CPB would be superior to placebo in facilitating separation from CPB. METHODS: High-risk cardiac surgical patients with PH were randomized to receive iMil or placebo after the induction of anesthesia and before CPB. Hemodynamic parameters and RV function were evaluated by means of pulmonary artery catheterization and transesophageal echocardiography. The groups were compared for the primary outcome of the level of difficulty in weaning from CPB. Among the secondary outcomes examined were the reduction in the severity of PH, the incidence of RV failure, and mortality. RESULTS: Of the 124 patients randomized, the mean (standard deviation [SD]) EuroSCORE II was 8.0 (2.6), and the baseline mean (SD) systolic pulmonary artery pressure (SPAP) was 53 (9) mmHg. The use of iMil was associated with increases in cardiac output (P = 0.03) and a reduction in SPAP (P = 0.04) with no systemic hypotension. Nevertheless, there was no difference in the combined incidence of difficult or complex separation from CPB between the iMil and control groups (30% vs 28%, respectively; absolute difference, 2%; 95% confidence interval [CI], -14 to 18; P = 0.78). There was also no difference in RV failure between the iMil and control groups (15% vs 14%, respectively; difference, 1%; 95% CI, -13 to 12; P = 0.94). Mortality was increased in patients with RV failure vs those without (22% vs 2%, respectively; P < 0.001). CONCLUSION: In high-risk cardiac surgery patients with PH, the prophylactic use of iMil was associated with favourable hemodynamic effects that did not translate into improvement of clinically relevant endpoints. This trial was registered at ClinicalTrials.gov; identifier: NCT00819377.

RéSUMé: OBJECTIF: La milrinone inhalée est utilisée pour traiter l'hypertension pulmonaire (HP) mais son efficacité, son innocuité et ses effets prophylactiques pour faciliter le sevrage de la circulation extracorporelle (CEC) et prévenir la dysfonction ventriculaire droite (VD) n'ont pas encore été évalués dans le cadre d'une étude clinique. L'objectif de cette étude était d'examiner si la milrinone inhalée avant la CEC serait supérieure à un placebo pour faciliter le sevrage de la CEC. MéTHODE: Des patients de chirurgie cardiaque à risque élevé et souffrant d'HP ont été randomisés à recevoir de la milrinone inhalée ou un placebo après l'induction de l'anesthésie et avant la CEC. Les paramètres hémodynamiques et la fonction VD ont été évalués à l'aide d'un cathéter de l'artère pulmonaire et d'une échocardiographie transœsophagienne. Les groupes ont été comparés selon notre critère d'évaluation principal, soit le niveau de difficulté du sevrage de la CEC. Parmi les critères d'évaluation secondaires examinés figuraient la réduction de la gravité de l'HP, l'incidence d'insuffisance cardiaque droite et la mortalité. RéSULTATS: Au total, 124 patients ont été randomisés. Le score EuroSCORE II moyen (écart type [ÉT]) était de 8,0 (2,6), et la pression systolique de l'artère pulmonaire moyenne de base (ÉT) était de 53 (9) mmHg. L'utilisation de milrinone inhalée a été associée à des augmentations du débit cardiaque (P = 0,03) et à une réduction de la pression systolique de l'artère pulmonaire (P = 0,04) sans hypotension systémique. Toutefois, aucune différence n'a été observée dans l'incidence combinée de sevrage difficile ou complexe de la CEC entre le groupe milrinone inhalée et le groupe témoin (30 % vs 28 %, respectivement; différence absolue, 2 %; intervalle de confiance [IC] 95 %, −14 à 18; P = 0,78). Aucune différence n'a été observée non plus en matière d'insuffisance cardiaque droite entre le groupe milrinone inhalée et le groupe témoin (15 % vs 14 %, respectivement; différence, 1 %; IC 95 %, −13 à 12; P = 0,94). La mortalité était augmentée chez les patients avec insuffisance cardiaque droite (22 % vs 2 %, respectivement; P < 0.001). CONCLUSION: Chez les patients de chirurgie cardiaque à risque élevé atteints de HP, l'utilisation prophylactique de milrinone inhalée a été associée à des effets hémodynamiques favorables qui ne se sont pas traduits en améliorations des critères pertinents d'un point de vue clinique. Cette étude a été enregistrée au ClinicalTrials.gov; identifiant : NCT00819377.

Exploring Attitudes of Children 12-17 Years of Age Toward Electronic Cigarettes.

The purpose of this study is to explore electronic cigarettes (EC) use among youth. Focus group sessions with youth (aged 12-17) were held to explore their knowledge and attitudes about EC use. Content analysis techniques were used. There has been an increase in the visibility and accessibility of EC in the past few years among youth. Compared with conventional cigarettes (CC), youth indicated that they would be more willing to use EC under their peer influence. This was motivated by the perception that EC were less harmful. Among youth EC are perceived as less harmful, easier to access and use than CC. Youth do not appear to have received much education about EC. However, they were not convinced that EC were risk free. Clear and unambiguous education about the risk of engaging in any form of smoking/vaping and enforcement of access restrictions appear to be required.

Waterpipe (Hookah) Smoking Among Youth and Women in Canada is New, not Traditional.

INTRODUCTION: When asserting the right of individuals to be free to smoke a hookah (waterpipe [WP]) in public places, the "cultural" importance of the practice is often cited. The purpose of this study was to explore the cultural significance of WP smoking. METHODS: Qualitative methods were used to elicit the views of groups of WP smokers from different cultural backgrounds. RESULTS: Sixteen group discussion sessions with a total of 75 WP smokers aged between 18 and 30 were conducted. A few participants saw culture as a factor supporting WP smoking initiation and maintenance. The vast majority indicated that WPs being perceived as "healthier" than cigarettes, and the availability of flavored shisha as important factors in their initiation and ongoing use. Most started smoking before the age of 18 calling it a "high school thing" and admitted that they had easy access to WP cafés. Many indicated that they did not know if they were smoking tobacco or a "herbal" substance. CONCLUSION: Peer influence, availability of flavored products and facile access to WP cafés are major factors in WP initiation. Ethno-cultural traditions play only a minor role. The assertion that cultural traditions and practice are inherent in WP smoking as implied by media and marketing was not supported by our findings. Contemporary use of WP is spreading among new non-traditional users. Lack of knowledge about the harms of WP smoking indicates a need for education and regulation to require packaging and health warning labels and restrictions on access, especially to minors.

Knowledge About the Waterpipe (Hookah), a Qualitative Assessment Among Community Workers in a Major Urban Center in Canada.

Waterpipe (WP) use has surged in popularity since the introduction of flavoured shisha. It is now an increasingly popular form of smoking among youth in North America. Health professionals/educators knowledge about the WP may well be inadequate. This study, using qualitative methods, sought to explore the knowledge and attitude of leaders in the community toward the WP. Family physicians, pharmacists, tobacco counsellors, social workers and educators were invited to participate in a one-one interview using open-ended questions. A total of 27 interviews were conducted. Individuals from Eastern Mediterranean backgrounds raised doubt about the overemphasised cultural significance of the WP and perceived this as a marketing strategy by industry. Most felt that WP smokers believed the WP to be less harmful than cigarettes and that the use of flavoured tobacco was motivating people to smoke. Participants believed that education should be directed at the general public and healthcare professionals, suggesting school programs and the use of social media to inform young smokers. Most thought that the current practices regarding packaging and second hand smoke exposure are confusing. They identified the lack of knowledge, poor enforcement procedures, "so called cultural aspects" and the economic impact of banning the WP on small businesses as barriers to change. Despite the awareness of an increase in WP use, our participants recognized that little has been done to curb this problem. Our findings emphasize the need for further education and better legislation to regulate WP use and availability.

Expanding the reach of the Quitline by engaging volunteers to market it in hospitals and shopping venues - a pilot study.

BACKGROUND: In Canada, although there are periodic media campaigns to raise awareness of Quitlines, these services are underused. We sought to determine if a dedicated kiosk, similar to that used in the retail industry but staffed by volunteers trained in smoking cessation techniques, would be effective method to enhance Quitline reach. METHODS: We located a kiosk in the foyer of two hospitals and in two shopping malls in Edmonton, Canada between Feb/2012 and July/2014. The cessation intervention was based on the 5 A's approach. Outcome was assessed by number of visits to the kiosk and referral rates to the Quitline. A cross sectional survey among small sample of visitors was used for evaluation. Descriptive statistics were used to summarize visitors' data. RESULTS: Of 1091 kiosk visitors, 53.3 % were current smokers, of whom 93.3 % indicated a willingness to quit. Of these, 32.1 % requested a Quitline referral at the time of the kiosk visit. Referral requests to the Quitline were greater when the kiosk was located in the non-hospital setting 39.1 % compared to 31.1 % in hospitals (P = 0.2). Referrals from the kiosk represented 6 % of total referrals received by the provincial Quitline during the study period. Following referral the Quitline was able to reach 50 % of those referred, of those, 17 % refused to proceed. At seven month follow up 30 day abstinence rate was 3.8 % of smokers who wished quit. Visitors agreed that the kiosk design was interesting (89.3 %) and increased their knowledge about tobacco and cessation options (88.8 %) and encouraged them to take action to quit (85.7 %). CONCLUSIONS: A "volunteer manned kiosk" can increase awareness of smoking cessation resources in the community and increase referral rates to Quitline services.

Quantification of wave reflection using peripheral blood pressure waveforms.

This paper presents a novel minimally invasive method for quantifying blood pressure (BP) wave reflection in the arterial tree. In this method, two peripheral BP waveforms are analyzed to obtain an estimate of central aortic BP waveform, which is used together with a peripheral BP waveform to compute forward and backward pressure waves. These forward and backward waves are then used to quantify the strength of wave reflection in the arterial tree. Two unique strengths of the proposed method are that 1) it replaces highly invasive central aortic BP and flow waveforms required in many existing methods by less invasive peripheral BP waveforms, and 2) it does not require estimation of characteristic impedance. The feasibility of the proposed method was examined in an experimental swine subject under a wide range of physiologic states and in 13 cardiac surgery patients. In the swine subject, the method was comparable to the reference method based on central aortic BP and flow. In cardiac surgery patients, the method was able to estimate forward and backward pressure waves in the absence of any central aortic waveforms: on the average, the root-mean-squared error between actual versus computed forward and backward pressure waves was less than 5 mmHg, and the error between actual versus computed reflection index was less than 0.03.

'Herbal' but potentially hazardous: an analysis of the constituents and smoke emissions of tobacco-free waterpipe products and the air quality in the cafés where they are served.

BACKGROUND: There are limited data on the composition and smoke emissions of 'herbal' shisha products and the air quality of establishments where they are smoked. METHODS: Three studies of 'herbal' shisha were conducted: (1) samples of 'herbal' shisha products were chemically analysed; (2) 'herbal' and tobacco shisha were burned in a waterpipe smoking machine and main and sidestream smoke analysed by standard methods and (3) the air quality of six waterpipe cafés was assessed by measurement of CO, particulate and nicotine vapour content. RESULTS: We found considerable variation in heavy metal content between the three products sampled, one being particularly high in lead, chromium, nickel and arsenic. A similar pattern emerged for polycyclic aromatic hydrocarbons. Smoke emission analyses indicated that toxic byproducts produced by the combustion of 'herbal' shisha were equivalent or greater than those produced by tobacco shisha. The results of our air quality assessment demonstrated that mean PM2.5 levels and CO content were significantly higher in waterpipe establishments compared to a casino where cigarette smoking was permitted. Nicotine vapour was detected in one of the waterpipe cafés. CONCLUSIONS: 'Herbal' shisha products tested contained toxic trace metals and PAHs levels equivalent to, or in excess of, that found in cigarettes. Their mainstream and sidestream smoke emissions contained carcinogens equivalent to, or in excess of, those of tobacco products. The content of the air in the waterpipe cafés tested was potentially hazardous. These data, in aggregate, suggest that smoking 'herbal' shisha may well be dangerous to health.

Smoking status and survival: impact on mortality of continuing to smoke one year after the angiographic diagnosis of coronary artery disease, a prospective cohort study.

BACKGROUND: Smoking is an undertreated risk factor for coronary artery disease (CAD) and is associated with adverse outcomes after myocardial infarction. Aims of our study were to determine if management of CAD by medical therapy (MT) alone or with coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) influence smoking status at one year following angiography and if a change in smoking status at one year influences long term survival. METHODS: Prospective cohort study using the APPROACH registry. Two cohorts were examined: (1) 11,334 patients who returned a one year follow-up questionnaire; (2) 4,246 patients propensity-matched based on their post-angiography treatment - MT or revascularization (RV). Multivariate modeling and survival analysis were used. RESULTS: In the propensity-matched cohort, quit rates at one year were greater among CABG patients (68%) than PCI (37%) or MT patients (47%). Smokers in the RV group, who self-reported quitting at one year, had a significantly reduced mortality compared to those who continued to smoke. CONCLUSIONS: CABG patients were more likely to quit smoking than those treated with MT alone or PCI. Quitting smoking was associated with improved long-term survival; smoking remains a key risk factor for mortality in patients with CAD. These data underscore the importance of nicotine addiction management in patients with CAD and the need to emphasize cessation particularly in those patients undergoing MT or PCI.

Subject-specific estimation of central aortic blood pressure via system identification: preliminary in-human experimental study.

This paper demonstrates preliminary in-human validity of a novel subject-specific approach to estimation of central aortic blood pressure (CABP) from peripheral circulatory waveforms. In this "Individualized Transfer Function" (ITF) approach, CABP is estimated in two steps. First, the circulatory dynamics of the cardiovascular system are determined via model-based system identification, in which an arterial tree model is characterized based on the circulatory waveform signals measured at the body's extremity locations. Second, CABP waveform is estimated by de-convolving peripheral circulatory waveforms from the arterial tree model. The validity of the ITF approach was demonstrated using experimental data collected from 13 cardiac surgery patients. Compared with the invasive peripheral blood pressure (BP) measurements, the ITF approach yielded significant reduction in errors associated with the estimation of CABP, including 1.9-2.6 mmHg (34-42 %) reduction in BP waveform errors (p < 0.05) as well as 5.8-9.1 mmHg (67-76 %) and 6.0-9.7 mmHg (78-85 %) reductions in systolic and pulse pressure (SP and PP) errors (p < 0.05). It also showed modest but significant improvement over the generalized transfer function approach, including 0.1 mmHg (2.6 %) reduction in BP waveform errors as well as 0.7 (20 %) and 5.0 mmHg (75 %) reductions in SP and PP errors (p < 0.05).

Data-driven lossy tube-load modeling of arterial tree: in-human study.

In this paper, we present and validate a data-driven method to lossy tube-load modeling of arterial tree in humans. In the proposed method, the lossy tube-load model is fitted to central aortic and peripheral blood pressure (BP) waves in the time domain. For this purpose, we employ a time-domain lossy tube-load model in which the wave propagation constant is formulated to two terms: one responsible for the alteration of wave amplitude and the other for the transport delay. Using the experimental BP data collected from 17 cardiac surgery patients, we showed that the time-domain lossy tube-load model is able to accurately represent the relation between central aortic versus upper-limb and lower-limb BP waves. In addition, the comparison of lossy versus lossless tube-load models revealed that (1) the former outperformed the latter in general with the root-mean-squared errors (RMSE) of 3.1 mm Hg versus 3.5 mm Hg, respectively (p-value < 0.05), and (2) the efficacy of the former over the latter was more clearly observed in case the normalized difference in the mean central aortic versus peripheral BP was large; when the difference was >5% of the underlying mean BP, lossy and lossless models showed the RMSE of 2.7 mm Hg and 3.7 mm Hg, respectively (p-value < 0.05).

Comparative study on tube-load modeling of arterial hemodynamics in humans.

In this paper, we assess the validity of two alternative tube-load models for describing the relationship between central aortic and peripheral arterial blood pressure (BP) waveforms in humans. In particular, a single-tube (1-TL) model and a serially connected two-tube (2-TL) model, both terminated with a Windkessel load, are considered as candidate representations of central aortic-peripheral arterial path. Using the central aortic, radial and femoral BP waveform data collected from eight human subjects undergoing coronary artery bypass graft with cardiopulmonary bypass procedure, the fidelity of the tube-load models was quantified and compared with each other. Both models could fit the central aortic-radial and central aortic-femoral BP waveform pairs effectively. Specifically, the models could estimate pulse travel time (PTT) accurately, and the model-derived frequency response was also close to the empirical transfer function estimate obtained directly from the central aortic and peripheral BP waveform data. However, 2-TL model was consistently superior to 1-TL model with statistical significance as far as the accuracy of the central aortic BP waveform was concerned. Indeed, the average waveform RMSE was 2.52 mmHg versus 3.24 mmHg for 2-TL and 1-TL models, respectively (p < 0.05); the r² value between measured and estimated central aortic BP waveforms was 0.96 and 0.93 for 2-TL and 1-TL models, respectively (p < 0.05). We concluded that the tube-load models considered in this paper are valid representations that can accurately reproduce central aortic-radial/femoral BP waveform relationships in humans, although the 2-TL model is preferred if an accurate central aortic BP waveform is highly desired.

Doxycycline reduces cardiac matrix metalloproteinase-2 activity but does not ameliorate myocardial dysfunction during reperfusion in coronary artery bypass patients undergoing cardiopulmonary bypass.

OBJECTIVES: Matrix metalloproteinase-2 proteolyzes intracellular proteins in the heart and induces acute myocardial contractile dysfunction in ischemia-reperfusion injury. Doxycycline, a matrix metalloproteinase inhibitor, prevented matrix metalloproteinase-2-induced troponin I cleavage in rat hearts and improved contractile function following ischemia-reperfusion. In patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass, increased atrial matrix metalloproteinase-2 activity was inversely correlated with cardiac mechanical function at 3 hours reperfusion. We performed a study in patients with coronary artery disease undergoing primary elective coronary artery bypass graft surgery with cardiopulmonary bypass to determine whether doxycycline reduces cardiac mechanical dysfunction, matrix metalloproteinase activity, and troponin I degradation after reperfusion. DESIGN: Randomized, double-blinded, placebo-controlled study. SETTING: University of Alberta Hospital. PATIENTS: Forty-two patients with coronary artery disease undergoing coronary artery bypass graft surgery with cardiopulmonary bypass. INTERVENTIONS: Patients were randomized to receive either oral administration of 20 mg of doxycycline or matching placebo pill twice a day at least 2 days prior to surgery, on the day of surgery, and for the first 3 postoperative days. MEASUREMENTS AND MAIN RESULTS: Left ventricular stroke work index was examined prior to cardiopulmonary bypass and at 24 hours reperfusion. Right atrial biopsies were collected before cardiopulmonary bypass and 10 minutes after aortic cross-clamp release to determine matrix metalloproteinase-2 activity and troponin I level. Blood was collected to determine matrix metalloproteinase activity and interleukin-6, C-reactive protein, and troponin I levels. Cardiac 72-kDa matrix metalloproteinase-2 activity was lower upon reperfusion in biopsies from the doxycycline group (p = 0.01), and the increase of matrix metalloproteinase-2 activity in the placebo group due to reperfusion did not appear in the doxycycline group (p = 0.05). Doxycycline, however, did not ameliorate cardiac mechanical dysfunction following reperfusion or the cardiopulmonary bypass-coronary artery bypass graft-induced increased plasma matrix metalloproteinase-9, interleukin-6, and C-reactive protein levels. Cardiopulmonary bypass-coronary artery bypass graft or doxycycline did not change tissue or plasma troponin I levels at 10 minutes reperfusion. CONCLUSIONS: Although doxycycline did not improve myocardial stunning following coronary artery bypass graft surgery with cardiopulmonary bypass, it reduced cardiac matrix metalloproteinase-2 activity in these patients. A larger trial and/or higher dose of doxycycline may yet be warranted.

Future physicians and tobacco: an online survey of the habits, beliefs and knowledge base of medical students at a Canadian University.

BACKGROUND: Little is known about the knowledge and attitudes towards tobacco use among medical students in Canada. Our objectives were to estimate the prevalence of tobacco use among medical students, assess their perceived level of education about tobacco addiction management and their preparedness to address tobacco use with their future patients. METHODS: A cross-sectional online survey was administered to University of Alberta undergraduate medical school trainees. The 32-question survey addressed student demographics, tobacco use, knowledge and attitudes around tobacco and waterpipe smoking, tobacco education received in medical school, as well as knowledge and competency regarding tobacco cessation interventions. RESULTS: Of 681 polled students, 301 completed the survey. Current (defined as "use within the last 30 days") cigarette, cigar/cigarillo and waterpipe smoking prevalence was 3.3%, 6% and 6%, respectively. One third of the respondents had ever smoked a cigarette, but 41% had tried cigars/cigarillos and 40% had smoked a waterpipe at some time in the past. Students reported moderate levels of education on a variety of tobacco-related subjects but were well-informed on the role of tobacco in disease causation. The majority of students in their final two years of training felt competent to provide tobacco cessation interventions, but only 10% definitively agreed that they had received enough training in this area. CONCLUSIONS: Waterpipe exposure/current use was surprisingly high among this sample of medical students, a population well educated about the role of tobacco in disease causation. The majority of respondents appeared to be adequately prepared to manage tobacco addiction but education could be improved, particularly training in behavioral modification techniques used in tobacco use cessation.

Impact of smoke-free hospital grounds policies: patient experiences and perceptions.

Implementation of a smoke-free hospital grounds policy changes the health care context for patients. This article examines patient's perspectives, providing insight into the shifting culture of smoking in hospitals and the impact of smoke-free policy during hospitalization. This qualitative study used semi-structured interviews (N=82) to explore patient perspectives of tobacco use, policy compliance, and abstinence support in Canadian hospitals with smoke-free grounds policies. Results indicated general support for smoke-free policies, but also highlighted that the intended goals were not realized; patients reported the policy is routinely violated, second-hand smoke exposure remained common at hospital entrances and assessment and treatment of tobacco dependency was inadequate. Patients provided rationales for policy violation, which included significant concern for personal safety. Health authorities must lend careful consideration to the effects of policy on hospitalization. Study results highlight patient views on tobacco dependence, hospitalization, and treatment expectations, which when adequately addressed could support abstinence, promote healthy recovery and hospital policy compliance.