This study assessed the association between hyaluronic acid (HA) injections and time-to-total knee replacement (TKR) surgery for patients with knee osteoarthritis (OA). Patients 18 to 64 years of age who had TKR surgery between January 1, 2006 and December 31, 2011 were identified from the MarketScan Commercial claims database. All patients had 6 years or more of continuous enrollment prior to TKR surgery. There were two cohorts (1) patients with HA injections prior to TKR surgery and (2) patients who did not have HA injections prior to TKR surgery. Time-to-TKR was defined as the total days from the date of diagnosis of knee OA on the patient's first visit to an orthopedic surgeon to the date of TKR surgery. Results included 22,555 patients who had TKR surgery: 14,132 in the non-HA and 8,423 in the HA cohort. In this retrospective analysis of patients undergoing TKR, the median Time-to-TKR surgery was 326 days for the non-HA and 908 days for the HA cohort, a difference of 582 days. Those receiving HA injections had a median 1.6-year longer Time-to-TKR surgery versus those who did not receive HA injections. These results have both clinical and economic implications.

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We have recorded auditory evoked potentials before and during cardiopulmonary bypass in 10 adult patients undergoing cardiac surgery under moderate hypothermia to 27-28 degrees C. The immediate effect of bypass was a small decrease in latency and increase in amplitude of the early cortical response. We also studied two adults and two children during profound hypothermia with circulatory arrest during cardiopulmonary bypass. Reduction in core temperature to 25 degrees C resulted in an increase in latency and amplitude of the brain stem responses; below this temperature the amplitude decreased but latency continued to increase until the auditory evoked response trace became completely flat between 21 and 19 degrees C. These changes were reversible on rewarming.

Total serum calcium, its fractions and serum citrate concentrations were measured in children receiving massive blood transfusion for scoliosis surgery, and in other children undergoing open heart surgery with cardiopulmonary bypass. During scoliosis surgery, although up to 100% of blood volume was replaced, and no additional calcium salts were infused, serum ionized calcium concentration remained within normal limits, provided that infusion rates of blood did not exceed 30 ml kg-1 h-1. During cardiopulmonary bypass, in which citrate-containing blood priming solutions were used, serum ionized calcium concentrations decreased markedly during perfusion associated with extremely high serum citrate concentrations. Serum ionized calcium concentrations returned to normal by the end of bypass, but serum citrate concentrations remained five times the normal concentration 5 h after bypass.