Browsing by Subject "Hemodynamics"
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Item The Association Between Tobacco Use and Intradialytic Hemodynamics in Hemodialysis Patients(2018-01-23) Sonderman, Mark; Van Buren, Peter NoelBACKGROUND: Intradialytic hypotension is known to be associated with increased mortality in maintenance hemodialysis patients. Smoking is a modifiable risk factor that is more commonly seen in patients with large decreases in intradialytic blood pressure as compared to any other intradialytic blood pressure pattern. However, the mechanisms of this association are unknown. We sought to explore the effect of lifetime tobacco use on vascular hemodynamics during dialysis. METHODS: We used impedance cardiography to measure total peripheral resistance index (TPRI) in 65 hypertensive hemodialysis patients. Additionally, we obtained blood pressure measurements before, during, and after midweek hemodialysis treatments. We then compared intradialytic hemodynamic changes between never smokers (n=35) and current or former smokers (n=30) using simple and multivariable linear regression. RESULTS: The mean change in TPRI during a single dialysis session was -438 dynes/sec/cm2/m2 in smokers and -105 dynes/sec/cm2/m2 in non-smokers (p=0.1). The intradialytic systolic blood pressure nadir was 115 mmHg in smokers and 123 mmHg in non-smokers (p=0.1). In multivariable linear regression controlling for diabetes, ultrafiltration rate, and other factors associated with intradialytic blood pressure changes, smoking was independently associated with lower nadir SBP (p=0.01) with a trend to also have a greater decrease in TPRI (p=0.08). CONCLUSIONS: Hemodialysis patients with a smoking history demonstrate a tendency towards a greater reduction in intradialytic TPRI as compared to non-smokers, with a significant independent association for lower nadir SBP. Smoking status should be aggressively ascertained in dialysis patients with significant intradialytic hypotension, but further studies are required to determine the effect of smoking cessation on intradialytic hemodynamics.Item Central Hemodynamic Monitoring of Train Drivers in Western Russia(2020-01-21) Duncan, Steven G.; Chang, Mary P.; Orlov, Sergei A.; Gorenkov, Roman V.BACKGROUND: Train drivers are exposed to work-related stressors which contribute to higher rates of cardiovascular disease. No studies have characterized precursors of this effect in Western Russia. AIM: This project aims to identify early disturbances and trends in central hemodynamic parameters among young locomotive driver assistants in order to elucidate patterns of decompensation. METHODS: This study is a retrospective review of hemodynamic parameters among train conductors in the Moscow region of the Russian Federation from December 2003 to September 2004. Subjects underwent regular hemodynamic monitoring within this period before every train departure. Automated oscillometric methods were used to obtain resting measurements of blood pressure, cardiac output, pulse wave velocity, and systemic vascular resistance with the device "KAP CG osm – 'Globus'". Men with pre-existing hypertension were excluded. RESULTS: The sample was comprised of 168 individuals and 8674 unique measurements; the mean age was 26.2 ± 4.6 years with an average of 52 ± 17 measurements per person over 33.8 ± 8.9 weeks. The average values for each hemodynamic parameter were within normal limits. Across all measurements, heart rate showed the greatest time-independent variation while systolic blood pressure showed the least; coefficients of variation (σ/x̄) were 10.6% and 6.8% respectively. Hypertensive episodes were observed in 36.3% of participants. Strong, positive correlations were observed between diastolic blood pressure and systemic vascular resistance (r = 0.72, p < 0.001), systolic blood pressure and cardiac output (r = 0.71, p < 0.001) respectively. Older subjects tended to have higher diastolic blood pressure (r = 0.51, p < 0.001). Over time, systemic vascular resistance showed the greatest variance with an average upward trend when data were fit to a linear regression model. Increasing systemic vascular resistance over time was positively correlated with decreasing systolic blood pressure and increasing diastolic blood pressure. DISCUSSION: Persistent changes in central hemodynamics can precede the development of clinical arterial hypertension. The results of this study suggest that implementation of early monitoring and prophylactic measures may be beneficial for high-risk individuals.Item Cocaine Use and General Anesthesia: A Prospective Study of Cardiovascular Effects(2018-01-23) Vu, Kevin; Kim, Agnes; Lu, Rachael; Sharifi, Eve; Moon, Tiffany SunBACKGROUND: Cocaine usage in surgical patients is a concern for many hospitals. In large urban hospitals, up to 1.0% of elective surgical patients and 38% of major trauma victims may test positive for cocaine preoperatively. Previous retrospective studies have shown that cocaine positive surgical patients do NOT have an increase in adverse hemodynamic events, length of stay, or mortality compared to cocaine negative controls. However, prospective studies evaluating the impact of recent cocaine use on intraoperative hemodynamics plus inflammatory and cardiac biomarkers have not been undertaken. HYPOTHESIS: This study will test the hypothesis that patients who have 1) a preoperative toxicity screen that demonstrates recent cocaine use, are 2) undergoing non-emergent surgery with general anesthesia, and 3) have normal vital signs will NOT experience an increased incidence of adverse perioperative cardiovascular events compared to similar control patients with a negative toxicity screen. METHODS: This prospective study stratifies patients into cocaine positive and cocaine negative cohorts. Cocaine positive patients were non-toxic with positive urine toxicology, while cocaine negative patients were defined as having used cocaine in the past year with negative urine toxicology. Anesthesia protocol was standardized. The primary outcomes measured were intraoperative hemodynamics and vasoactive medications, with a secondary outcome of pre- vs. post-operative troponin levels. DATA: Preliminary outcome analysis of cocaine positive (N = 59) and cocaine negative patients (N = 40) are shown in the table below: Primary Hemodynamic Outcomes as Percentage of Anesthesia Duration Hemodynamic Events Cocaine Negative Cocaine Positive MAP <55 or >110 mmHG 1.8 1.4 HR <50 or >100 BPM 3.2 2.7 Perioperative Change in Troponin T No Change 95.0% 100.0% Decrease 2.5% 0.0% Increase 2.5% 0.0% CONCLUSION: The data supports the idea that positive cocaine urine toxicology tests in non-toxic individuals are not associated with increased cardiovascular instability or troponin elevation. Thus, automatic cancellation of these patients may not be warranted. Further analysis of the full study cohort (N = 300) will be completed at the end of 2017.Item Developing a Real-Time, Axially Resolving Optical Monitor of Spinal Cord Blood Flow(2019-01-22) Gao, Feng; Busch, David R.; Goh, Chia Chieh; Lin, Wei; Yodh, Arjun G.; Floyd, Thomas F.BACKGROUND: Spinal cord ischemia is a disease of high morbidity and mortality often caused by surgeries repairing the thoracic and abdominal aorta. Current methods to monitor spinal cord hemodynamics such as electrophysiology methods, MR arterial spin labeling, and laser Doppler either have a slow response time or are unfeasible intra-operatively. In this study, we developed an optical probe to monitor spinal cord blood flow and oxygenation in real-time at multiple sites along the spine. METHODS: Experiments were conducted on 8 adult domestic pigs. Probes were inserted into the epidural space through a laminotomy prior to asphyxia and local ischemia via catheter balloon inflation. Vital signs, anesthetic parameters, and spinal hemodynamics were measured continuously prior to intervention, throughout asphyxia, and during inflation/deflation of the balloon catheter. Optical blood flow measurements were compared against microspheres. Optical hemoglobin saturation of spinal cord was compared to mixed venous blood gases. RESULTS: The fiber optic probe detected changes in flow and oxygenation in all asphyxia and balloon inflation trials across multiple sites along the spine. We observed significant changes in spinal cord blood flow during balloon inflation in the epidural space. We also observed a significant correlation between optically measured hemoglobin saturation and mixed venous blood gases. CONCLUSION: We developed an intra-operative tool that provides continuous, real-time monitoring of spinal cord hemodynamics at multiple sites along the spine. We hope this tool can more safely guide surgeons in reducing the incidence of spinal cord ischemia.Item Hemodynamic assessment of aortic stenosis(1991-12-05) Grayburn, Paul A.