The thermal effects of intramedullary reaming

OBJECTIVE: To study the effect of tourniquet control on intramedullary reaming. DESIGN: An experimental prospective nonsurvival animal study was performed using 5 mongrel dogs. A pneumatic tourniquet was randomized to either the right or left hind limb. Tibial intramedullary reaming was performed with progressively larger reamers. Cortical temperatures were measured using thermocouples inserted into the tibial diaphyseal cortex. Thermocouples were connected to an analog to digital converter that output continuous data that was collected on a computer. Upon completion of the procedure, the animals were killed. RESULTS: The peak and low temperatures for each thermocouple with each reamer passage were recorded. Reamer sizes larger than the internal diameter of the intramedullary canal produced higher peak temperatures. The mean delta t (peak temperature minus low temperature) was calculated for each reamer passage. This measurement represents the overall amount of heat generated during each reamer passage. There were no significant differences between the 2 conditions (P = 0.8, paired t test). Temperatures decreased in between reamer exchange but did not return to baseline levels. CONCLUSIONS: Because similar temperatures were measured both with and without a tourniquet, the risk of thermal necrosis appears to be related more to the process of intramedullary reaming than to the tourniquet. Higher temperatures were measured with reamer sizes larger than the internal diameter of the intramedullary canal. Increasing the time interval between the passage of successive reamers may allow heat to dissipate and decrease the risk of thermal necrosis. The clinical practice of limited reaming ("ream-to-fit") should minimize the occurrence of this complication.     

An Australian casemix classification for palliative care: technical development and results

OBJECTIVES: To develop a palliative care casemix classification for use in all settings including hospital, hospice and home-based care. SAMPLE: 3866 palliative care patients who, in a three-month period, had 4596 episodes of care provided by 58 palliative care services in Australia and New Zealand. METHOD: A detailed clinical and service utilization profile was collected on each patient with staff time and other resources measured on a daily basis. Each day of care was costed using actual cost data from each study site. Regression tree analysis was used to group episodes of care with similar costs and clinical characteristics. RESULTS: In the resulting classification, the Australian National Sub-acute and Non-acute Patient (AN-SNAP) Classification Version 1, the branch for classifying inpatient palliative care episodes (including hospice care) has 11 classes and explains 20.98% of the variance in inpatient palliative care phase costs using trimmed data. There are 22 classes in the ambulatory palliative care branch that explains 17.14% variation in ambulatory phase cost using trimmed data. DISCUSSION: The term 'subacute' is used in Australia to describe health care in which the goal--a change in functional status or improvement in quality of life--is a better predictor of the need for, and the cost of, care than the patient's underlying diagnosis. The results suggest that phase of care (stage of illness) is the best predictor of the cost of Australian palliative care. Other predictors of cost are functional status and age. In the ambulatory setting, symptom severity and the model of palliative care are also predictive of cost. These variables are used in the AN-SNAP Version 1 classification to create 33 palliative care classes. The classification has clinical meaning but the overall statistical performance is only moderate. The structure of the classification allows for it to be improved over time as models of palliative care service delivery develop.     

Stress, trauma, and risky sexual behaviour among American Indians in young adulthood

This paper examines the relationship of risky sexual behaviour to stress and trauma-often the mediators of the content and structure of everyday life-among young American Indians. School, work, social life, and home life bring about demands and stresses for youth; choices young people make may depend on the quantity and content of those demands. Traumatic events or highly distressing situations may shatter fragile (or even resilient) systems of external and internal support from which youth may draw. American Indians live in some of the most impoverished areas of the country, where everyday life includes a heavy burden of stress and trauma. Using data from a representative sample of youth from a Northern Plains tribe, bivariate and adjusted ordered logit models are used to show that stress and trauma do play a role in the sexual decision-making of young people, especially young women. For example, young women who have experienced a trauma have a 20% probability of having had multiple casual partners in the prior year compared to 9% for those who have not experiences a trauma. Types and levels of stress and trauma also make a difference by gender.