Patellar tracking during simulated quadriceps contraction

The current study compared patella tracking during simulated concentric and eccentric quadriceps contractions in 12 knees from cadavers using a three-dimensional electromagnetic tracking system. The patella shifted (translated) and tilted medially during approximately the initial 22 degrees tibiofemoral flexion. The patella then shifted and tilted laterally for the remaining arc of tibiofemoral flexion (90 degrees). At 90 degrees tibiofemoral flexion, the patella had an orientation of lateral patella shift and lateral patella tilt. Patella shift was significantly more lateral between 40 degrees and 70 degrees tibiofemoral flexion during concentric quadriceps action than during eccentric contraction. Patella tilt was significantly more lateral between 45 degrees and 55 degrees tibiofemoral flexion during concentric quadriceps contraction than during eccentric action. No other significant differences were seen between the quadriceps contraction conditions. The current study supports the hypothesis that patellar instability is most likely a result of various anatomic and physiologic factors causing a failure of the extensor mechanism to deliver the patella into the femoral sulcus and that a patellar dislocation rarely would occur in a normal knee.     

The short-term and long-term effects of warm or tepid cardioplegia

BACKGROUND: Clinical studies of myocardial protection rarely identify differences in hard clinical outcomes after surgery, either early or late, because most trials lack sufficient statistical power to deal with low-frequency events. METHODS: Prospectively collected data concerning all isolated coronary bypass operations from November 1989 to February 2000 were analyzed to determine the effects of cold blood cardioplegia and warm or tepid blood cardioplegia on early and late outcomes after surgery. Warm blood cardioplegia was used in 4532 patients, whereas cold blood cardioplegia was used in 1532. The allocation of patients to receive warm blood cardioplegia and cold blood cardioplegia was random in 749 cases and according to surgeon preference in the remainder. Most patients in the cold blood cardioplegia group had surgery earlier in the time course of the study, and most in the warm blood cardioplegia group underwent surgery later. RESULTS: Perioperative death, myocardial infarction, and death or myocardial infarction were all more common in the cold blood cardioplegia group than in the warm blood cardioplegia group (death 2.5% vs 1.6%, P =.027, adjusted odds ratio 1.45, 95% confidence interval 0.95-2.22, P =.09; myocardial infarction 5.4% vs 2.4%, P <.0001, adjusted odds ratio 1.86, 95% confidence interval 1.36-2.53, P <.0001; death or myocardial infarction 7.3% vs. 3.8%, P <.0001, adjusted odds ratio 1.70, 95% confidence interval 1.30-2.21, P <.0001). Actuarial survival at 60 months was 91.1% +/- 1.4% in the warm blood cardioplegia group and 89.9% +/- 1.3% in the cold blood cardioplegia group (P =.09), whereas freedom from death or myocardial infarction was 84.7% +/- 1.8% and 83.2% +/- 1.6%, respectively (P =.16). In multivariate models, cold blood cardioplegia was associated with poorer survival (risk ratio 1.30, 95% confidence interval 0.96-1.75, P =.09) and freedom from any death or late myocardial infarction (risk ratio 1.93, 95% confidence interval 1.56-2.39, P =.0001). CONCLUSIONS: In 6064 patients undergoing isolated coronary artery bypass grafting, warm or tepid blood cardioplegia may be associated with better early and late event-free survivals than is cold cardioplegia.     

The health impact of health care on families: a matched cohort study of hospice use by decedents and mortality outcomes in surviving,widowed spouses

Alternative ways of caring for seriously ill patients might have implications not only for patients' own outcomes, but also, indirectly, for the health outcomes of their family members. Clinical observation suggests that patients who die "good deaths" may impose less stress on their spouses. Consequently, we sought to assess whether hospice use by a decedent is associated with decreased risk of death in surviving, bereaved spouses. We conducted a matched retrospective cohort study involving a population-based sample of 195,553 elderly couples in the USA. A total of 30,838 couples where the decedent used hospice care were matched using the propensity score method to 30,838 couples where the decedent did not use hospice care. Our principal outcome of interest was the duration of survival of bereaved widow/ers. After adjustment for other measured variables, 5.4% of bereaved wives died by 18 months after the death of their husband when their deceased husband did not use hospice and 4.9% died when their deceased husband did use hospice, yielding an odds ratio (OR) of 0.92 (95% CI: 0.84-0.99) in favor of hospice use. Similarly, whereas 13.7% of bereaved husbands died by 18 months when their deceased wife did not use hospice, 13.2% died when their deceased wife did use hospice, yielding an OR of 0.95 (95% CI: 0.84-1.06) in favor of hospice use. Our findings suggest a possible beneficial impact of hospice--as a particularly supportive type of end-of-life care--on the spouses of patients who succumb to their disease. Hospice care might attenuate the ordinarily increased mortality associated with becoming widowed. This effect is present in both men and women, but it is statistically significant and possibly larger in bereaved wives. The size of this effect is comparable to the reductions in the risk of death seen in a variety of other modifiable risk factors in women. Health care may have positive, group-level health "externalities": it may affect the health not only of patients but also of patients' family members.     

Effect of specific aspects of community social environment on the mortality of individuals diagnosed with serious illness

The purpose of this study was to examine the prospective and contextual effects of urban community environment on mortality among Medicare beneficiaries who were 67 years old or older in 1993, lived in the city of Chicago, and were hospitalized for one of 13 serious diseases. As expected, we found that advantageous socioeconomic context helps lower mortality risk among elderly patients over and above individual demographic and health background. We also found that collective efficacy was a health-enhancing social resource whereas criminal and violent activities in the community appeared to be deleterious. Inconsistent with our hypotheses, community social network density (measured by the size of social network and frequency of social interaction) was not protective but detrimental. Moreover, social support and the civic involvement of residents in the community do not seem to affect mortality. The complex relationship between community social environment and health found in this study may suggest that community-level social interventions based on social capital/social cohesion models are not likely to achieve fruitful results without concomitant effort in the economic and health care realm, at least in terms of influences on the health of older people once they are already ill.     

Extended rituximab therapy for previously untreated patients with Waldenström's macroglobulinemia

Waldenstr?m's macroglobulinemia is a low-grade lymphoplasmacytoid lymphoma characterized by CD20 expression on malignant cells. Several studies have indicated that the anti-CD20 monoclonal antibody rituximab has activity against this disease. Thus, we performed a prospective study in which 17 previously untreated patients with symptomatic macroglobulinemia were treated with rituximab 375 mg/m2 intravenously for 4 weeks. Three months after completion of rituximab, patients without evidence of progressive disease received repeat 4-week courses of this agent. Six patients (35%) achieved a partial response after extended treatment with rituximab. Median time to response was 3 months. The median time to progression (TTP) for all patients was 13 months. One of 6 responding patients has progressed at 10 months, while the other 5 patients remain progression free with a follow-up range of > 22-40 months. Eight patients (47%) were rated as stable disease, and their median TTP was 9 months. Treatment with rituximab was well tolerated and was not associated with myelosuppression; one third of the patients experienced infusion-related toxicity, usually fever and chills of mild degree. Our prospective trial of extended rituximab therapy for previously untreated patients with Waldenstr?m's macroglobulinemia indicates that this agent is active, well tolerated, and might be associated with a long period without the need for further treatment. Studies that will combine rituximab with chemotherapy or with other monoclonal antibodies might be of interest.     

Dipyridamole preserved platelets and reduced blood loss after cardiopulmonary bypass

Cardiopulmonary bypass activates and depletes platelets, which may contribute to postoperative bleeding. In addition, activated platelets may be deposited in the coronary vasculature after ischemia and cardioplegia, which may delay recovery of cardiac function and metabolism and may contribute to early bypass graft occlusion. The antiplatelet agent dipyridamole reduces platelet activation and depletion and may decrease postoperative bleeding and transfusion requirements. A prospective randomized trial was conducted in 58 patients undergoing elective coronary bypass operations to compare the effects of oral (19 patients) and intravenous (21 patients) dipyridamole to the results obtained in a control group (18 patients) who received no dipyridamole. Preoperative oral administration of dipyridamole resulted in lower plasma drug concentrations in the early postoperative period than perioperative intravenous administration (p = 0.0001 by analysis of variance). Postoperative arterial platelet counts were highest in the patients receiving intravenous dipyridamole, intermediate in those receiving oral dipyridamole, and lowest in the control group (p = 0.03 by analysis of variance). Postoperative blood loss and blood product transfusions were significantly reduced with both oral and intravenous dipyridamole (p = 0.04 by analysis of variance). Dipyridamole preserved platelets and reduced postoperative bleeding. Intravenous dipyridamole resulted in higher platelet counts than oral dipyridamole and may be required to reduce postoperative bleeding in high-risk patients.     

Decreased postoperative myocardial fatty acid oxidation

Myocardial substrate preferences following cardioplegic arrest for coronary bypass surgery have not been established. Fatty acids are believed to be the major fuel source for aerobic metabolism. Following cardioplegic arrest arterial fatty acid levels are elevated and myocardial fatty acid accumulation without oxidation may contribute to reperfusion injury. Perioperative fatty acid metabolism was evaluated in 18 patients undergoing elective coronary bypass surgery who were randomized to receive either blood (n = 11) or crystalloid (n = 7) cardioplegia. Palmitate labeled with 14carbon was infused perioperatively and arterial and coronary sinus blood samples were obtained to calculate myocardial fatty acid extraction and oxidation before and after cardioplegic arrest. Lactate and glycerol were released from the heart during both blood and crystalloid cardioplegia, suggesting ischemic glycolysis and lipolysis. Myocardial oxygen consumption was depressed and the myocardial consumptions of lactate, glucose, and fatty acids were minimal during the first 60 min after aortic clamp removal in both groups despite high arterial concentrations. Fatty acid oxidation was minimal after blood cardioplegia and was not found after crystalloid cardioplegia. Fatty acids were extracted by the heart, but were not aerobically metabolized following cardioplegic arrest. Myocardial fatty acid accumulation without oxidation may have been deleterious. The inability of the heart to oxidize exogenous fatty acids may reflect altered myocardial exogenous substrate preferences during reperfusion following coronary bypass surgery.