Rotary ventricular assist devices (VADs) are less sensitive to preload than the healthy heart, resulting in inadequate flow regulation in response to changes in patient cardiac demand. Starling‐like physiological controllers (SLCs) have been developed to automatically regulate VAD flow based on ventricular preload. An SLC consists of a cardiac response curve (CRC) which imposes a nonlinear relationship between VAD flow and ventricular preload, and a venous return line (VRL) which determines the return path of the controller. This study investigates the importance of a physiological VRL in SLC of dual rotary blood pumps for biventricular support. Two experiments were conducted on a physical mock circulation loop (MCL); the first compared an SLC with an angled physiological VRL (SLC‐P) against an SLC with a vertical VRL (SLC‐V). The second experiment quantified the benefit of a dynamic VRL, represented by a series of specific VRLs, which could adapt to different circulatory states including changes in pulmonary (PVR) and systemic (SVR) vascular resistance versus a fixed physiological VRL which was calculated at rest. In both sets of experiments, the transient controller responses were evaluated through reductions in preload caused by the removal of fluid from the MCL. The SLC‐P produced no overshoot or oscillations following step changes in preload, whereas SLC‐V produced 0.4 L/min (12.5%) overshoot for both left and right VADs. Additionally, the SLC‐V had increased settling time and reduced controller stability as evidenced by transient controller oscillations. The transient results comparing the specific and standard VRLs demonstrated that specific VRL rise times were improved by between 1.2 and 4.7 s ( = 3.05 s), while specific VRL settling times were improved by between 2.8 and 16.1 seconds ( = 8.38 s) over the standard VRL. This suggests only a minor improvement in controller response time from a dynamic VRL compared to the fixed VRL. These results indicate that the use of a fixed physiologically representative VRL is adequate over a wide variety of physiological conditions. 相似文献
ObjectiveTo propose the Intense Pulsed Light (IPL) therapy as a helpful supplementary treatment in patients with dry eye disease.Material and methodsRetrospective cross sectional design. Medical records of patients in whom dry eye disease symptoms were not satisfactorily controlled with medical therapy alone and who underwent additional IPL with at least three sessions completed. Data were analyzed before therapy and 3 weeks after its completion to asses improvement. Determination of symptoms, through a visual analog scale; tear film stability, through tear Break Up Time (tBUT); measurement of tear secretion, through Schirmer Test; and ocular surface staining with Van Bijsterveld score were evaluated. SPSS software and nonparametric analysis of repeated measures were used. The study was approved by the ethics committee.Results50 eyes from 25 subjects were reviewed. There were 9 males (36%) and 16 females (64%), with a median age of 59 years (IQR 52-64). The median of the symptoms scale was 8 (IQR 8-9) and 3 (IQR 2-4) before and after the therapy respectively (P < .05). The median of BUT was 4 (IQR 3-5) and 10 (IQR 8-11), Schirmer test was 13 (IQR 12-15) and 15 (IQR 13-20), and Van Bijsterveld score was 3 (RIC 3-4) and 2 (IQR 2-3) before and after the therapy respectively (P < .05, for all measurements).ConclusionIPL treatment has excellent results regarding both: dry eye disease symptoms improvement and in office objective tests such as tBUT, Schirmer test and Van Bijsterveld score; IPL could be considered as an effective adjunct for dry eye disease. 相似文献
Objectives: There is a paucity of reporting on surgical outcomes of isolated posterior cruciate ligament reconstruction (PCLR). We hypothesize that isolated PCL injuries failing nonoperative treatment achieve good outcomes and are able to return to sport following PCLR.
Methods: A retrospective analysis was performed to identify patients with isolated PCL injuries that underwent reconstruction between 2001 and 2014. Patients with multi-ligamentous injury or another concomitant knee pathology were excluded. Medical records were reviewed for demographic, clinical and operative data. Patients were contacted for administration of a telephone-based questionnaire which included the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation form, Lysholm-Tegner scales, Marx activity scale (MAS), return to sport status, and patient satisfaction instruments.
Results: A total of 15 isolated PCL reconstructions in 14 patients with a mean age of 27.5 years (range 17–43) met the study inclusion criteria; mean follow up was 6.3 years (range 1.4–15.2). Pre-operatively, the primary complaint was knee instability in all patients; on physical examination, lack of a firm end point during posterior drawer testing was found in 93% (14/15) of the knees. In total, 12 of 15 knees underwent transtibial, single-bundle PCLR and three of 15 underwent tibial inlay, double bundle PCLR. Graft types included: quadriceps autograft (7/15), Achilles allograft (6/15), and hamstring autograft (2/15). There were no graft failures in our patient cohort. At most recent follow up the mean scores respectively on the IKDC form, Lysholm-Tegner scales and MAS were (standard deviation): 77.3 (16.5), 83.1 (17.9), 6.13 (2.6), and 7.1 (6.0). All fourteen patients were athletes prior to their injury and 79% (11/14) returned to sport and overall patient satisfaction was 9.2/10.
Conclusions: Isolated PCLR provides good outcomes at mean medium-term follow up with restoration of function, high rate of return to sport and overall patient satisfaction. 相似文献
Online physician rating websites are increasingly used by patients to evaluate their doctors. The purpose of this investigation was to evaluate factors associated with better spine surgeon ratings.
METHODS
Orthopedic spine surgeons were randomly selected from the North American Spine Society directory utilizing a random number generator. Surgeon profiles on three physician rating websites, namely, www.HealthGrades.com, www.Vitals.com, and www.RateMDs.com, were analyzed to gather qualitative and quantitative data on patients’ perceptions of the surgeons. Independent variables from the websites were analyzed in relation to overall physician or patient satisfaction rating. Comments were coded by subject into following three categories: professional competence, bedside manner, and practice characteristics.
RESULTS
A total of 250 surgeons were evaluated, and 92% (n=230) of these doctors had at least one rating among the three websites. The surgeons with a higher average rating had significantly better trust (p<.01), scheduling (p<.01), staff (p<.01), helpfulness (p<.01), and punctuality (p<.01) scores but significantly less experience (p<.05). A linear regression model for the average rating of each surgeon (R2 value=0.754) yielded only following three significant variables: trustworthiness (p<.01), experience match (p<.05), and the average number of negative comments on surgeon's professional competence (p<.05). Trustworthiness (β=0.749) was the strongest predictor variable of physician rating, followed by the number of negative professional competence comments (β=?0.132) and experience match (β=?0.112).
CONCLUSIONS
This investigation assessed spine surgeon online patient ratings and categorized factors that patients associate with quality care. Trustworthiness was the most significant predictor of positive ratings, whereas ease of scheduling, quality of staff, helpfulness, and punctuality were also associated with higher patient ratings. Understanding what patients value may help optimize care of spine surgery patients. 相似文献
Etomidate is frequently selected over propofol for induction of anaesthesia because of a putatively favourable haemodynamic profile, but data confirming this perception are limited.
Methods
Patients undergoing cardiac surgery were randomised to induction of anaesthesia with propofol or etomidate. Phase I (n=75) was conducted as open-label, whereas Phase II (n=75) was double blind. Mean arterial blood pressure (MAP) and boluses of vasopressor administered after induction were recorded. The primary endpoint was the area under the curve below baseline MAP (MAP-time integral) during the 10 min after induction. Secondary endpoints were the use of vasopressors over the same period, and the effect of blinding on the aforementioned endpoints. Groups were compared using regression models with phase and anaesthetist as factors.
Results
The mean difference between etomidate and propofol in the MAP-time integral below baseline was 2244 mm Hg s (95% confidence interval, 581–3906; P=0.009), representing a 34% greater reduction with propofol. Overall, vasopressors were used in 10/75 patients in the etomidate group vs 21/75 in the propofol group (P=0.38), and in 20/74 patients during the blinded phase vs 11/76 during the open-label phase (P=0.31). The interaction between randomisation and phase (open-labelled or blinded) was not significant for either primary (P=0.73) or secondary endpoints (P=0.90).
Conclusions
Propofol caused a 34% greater reduction in MAP-time integral from baseline after induction of anaesthesia than etomidate, despite more frequent use of vasopressors with propofol, confirming the superior haemodynamic profile of etomidate in this context. The proportion of patients receiving vasopressors increased slightly, albeit not significantly, in both groups in the blinded phase.
Clinical trial registration
Australian and New Zealand Clinical Trials Registry, ACTRN12614000717651. 相似文献