Steffey E P, Laster M J, Ionescu P, Eger E I, Gong D, Weiskopf R B
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, USA.
Anesth Analg. 1997 Dec;85(6):1382-6. doi: 10.1097/00000539-199712000-00037.
In a model anesthetic circuit, dehydration of Baralyme brand carbon dioxide absorbent increases degradation of sevoflurane to CF2=C(CF3)OCH2F, a nephrotoxic vinyl ether called Compound A. In the present study, we quantified this increase using "conditioned" Baralyme in a circle absorbent system to deliver sevoflurane anesthesia to swine. Mimicking continuing oxygen delivery for 2 days after completion of an anesthetic, we directed a conditioning fresh gas flow of 5 L/min retrograde through fresh absorbent in situ in a standard absorbent system for 40 h. The conditioned absorbent was subsequently used (without mixing of the granules) in a standard anesthetic circuit to deliver sevoflurane to swine weighing 78 +/- 2 kg. The initial inflow rate of fresh gas flow was set at 10 L/min with the vaporizer at 8% to achieve the target end-tidal concentration of 3.0%-3.2% sevoflurane in approximately 20 min. The flow was later decreased to 2 L/min, and the vaporizer concentration was decreased to sustain the 3.0%-3.2% value for a total of 2 h (three pigs) or 4 h (eight pigs). Inspired Compound A increased over the first 30 +/- 60 min to a peak concentration of 357 +/- 49 ppm (mean +/- SD), slowly decreasing thereafter to 74 +/- 6 ppm at 4 h. The average concentration over 2 h was 208 +/- 25 ppm, and the average concentration over 4 h was 153 +/- 19 ppm. Pigs were killed 1 or 4 days after anesthesia. The kidneys from pigs anesthetized for both 2 h and 4 h showed mild inflammation but little or no tubular necrosis. These results suggest that dehydration of Baralyme may produce concentrations of Compound A that would have nephrotoxic effects in humans in a shorter time than would be the case with normally hydrated Baralyme.
The vapor known as Compound A can injure the kidney. Dehydration of Baralyme, a standard absorbent of carbon dioxide in inhaled anesthetic delivery systems, can cause a 5- to 10-fold increase in Compound A concentrations produced from the inhaled anesthetic, sevoflurane, given at anesthetizing concentrations in a conventional anesthetic system.
在一个模拟麻醉回路中，碱石灰品牌的二氧化碳吸收剂脱水会增加七氟醚降解为CF2=C(CF3)OCH2F，这是一种名为化合物A的具有肾毒性的乙烯基醚。在本研究中，我们在循环吸收系统中使用“预处理过的”碱石灰对七氟醚麻醉的猪进行实验，以量化这种增加。模拟麻醉结束后持续供氧2天的情况，我们将5 L/min的预处理新鲜气流逆行通过标准吸收系统中原位的新鲜吸收剂，持续40小时。随后，将预处理过的吸收剂（不混合颗粒）用于标准麻醉回路，向体重78±2 kg的猪输送七氟醚。新鲜气流的初始流入速率设定为10 L/min，蒸发器设定为8%，以便在大约20分钟内达到3.0%-3.2%的七氟醚目标呼气末浓度。随后流量降至2 L/min，蒸发器浓度降低，以维持3.0%-3.2%的值，持续2小时（三头猪）或4小时（八头猪）。吸入的化合物A在最初30±60分钟内增加到峰值浓度357±49 ppm（平均值±标准差），此后缓慢下降，4小时时降至74±6 ppm。2小时内的平均浓度为208±25 ppm，4小时内的平均浓度为153±19 ppm。猪在麻醉后1天或4天处死。麻醉2小时和4小时的猪的肾脏显示有轻度炎症，但几乎没有或没有肾小管坏死。这些结果表明，碱石灰脱水可能产生的化合物A浓度，在比正常水合碱石灰更短的时间内就会对人体产生肾毒性作用。
名为化合物A的蒸汽会损害肾脏。碱石灰是吸入麻醉输送系统中标准的二氧化碳吸收剂，其脱水会导致在传统麻醉系统中以麻醉浓度给予吸入麻醉剂七氟醚时产生的化合物A浓度增加5至10倍。
