Effect of calcium replacement on the hemodynamic changes associated with high dose interleukin-2 therapy.

Administration of high-dose IL-2 results in hemodynamic changes that are similar to those seen in septic shock. These include a decrease in systemic vascular resistance (SVR) with a resultant drop in mean arterial pressure (MAP). Hypocalcemia is seen in septic shock and with IL-2 administration. Calcium replacement in septic shock has been reported to result in hemodynamic improvement; we therefore administered calcium to patients receiving high dose IL-2 to correct ionized hypocalcemia. Five consecutive patients underwent invasive hemodynamic monitoring before and during IL-2 administration. Calcium chloride was administered to correct ionized hypocalcemia, and hemodynamic parameters were monitored before and after calcium administration. Ionized hypocalcemia was associated with an elevation in parathyroid hormone levels. There was no toxicity related to the administration of calcium. An improvement in the MAP and SVR was seen early and late (after a dose of IL-2 was held) in the IL-2 treatment cycle; there were minimal effects at other points. Because of the potential hemodynamic benefit of calcium replacement, we recommend that ionized hypocalcemia be corrected in patients receiving high-dose IL-2.     

Use of laser to extract unwanted pacemaker leads

Of the total number of pacemakers implanted each year, 6% must eventually be replaced because of infection, lead failure, or other problems. Often however, removal of the pacing leads is precluded by scarring at the tip of the leads. Because abandoned leads can cause serious problems, we initiated the present study to test the feasibility of using a laser to remove such leads. After performing in vitro experiments to establish the laser settings required for severing leads, we implanted 6 leads, from 4 different manufacturers, in 3 dogs. Five weeks later, we passed a laser fiber through each lead to the tip and delivered a 10-watt impulse for 2 seconds, which resulted in the successful removal of all the leads. When the dogs were killed 3 days later, postmortem examination revealed no thromboembolism in the heart or lungs and no myocardial damage. Subsequent experiments in 3 human cadaver hearts-involving leads implanted for 5 years, 2 years, and 2 months-yielded the same satisfactory results as did the canine experiments.     

An evaluation of commercial radioisotope methods for the determination of folate and vitamin B12.

Five commercial kits for the determination of folate and six kits for the determination of vitamin B12 were investigated. Their performance has been compared with microbiological methods for the two vitamins and with a non-commercial radioisotopic method for B12. The results show the importance of the determination of the reference range for an individual laboratory for each method. The precision of the kits varied appreciably, as did their performance using specimens from patients with different haematological disorders. In particular, certain kits failed to detect all patients with pernicious anaemia. The relative accuracy of the kits was assessed. Various factors which should be taken into account in the final selection of a satisfactory kit are discussed.