Clinic of Anesthesiology, Hannover Medical School, Hannover, Germany.
Clinic of Anesthesiology, KRH Klinikum Robert Koch, Gehrden, Germany.
Paediatr Anaesth. 2022 Aug;32(8):961-966. doi: 10.1111/pan.14494. Epub 2022 May 31.
Intravenous fluids for perioperative infusion therapy should be isotonic to maintain the body fluid homeostasis in children. Modified fluid gelatin 4% in a balanced electrolyte solution has a theoretical osmolarity of 284 mosmol L , and a real osmolality of 264 mosmol kg H O . Because both values are lower than those of 0.9% saline or plasma, gelatin would be expected to be hypotonic in-vitro and in-vivo.
We thus hypothesized that the infusion of gelatin would be expected to decrease plasma osmolality. We performed an in-vitro experiment and an in-vivo study to evaluate the impact of gelatin on the osmolality in children.
In the in-vitro experiment, full blood samples were diluted with gelatin 4% or albumin (50 g L ) from 0% (pure blood) to 100% (pure colloid), and the osmolality was measured by freezing-point depression. In the in-vivo study, blood gas analyses from children undergoing major pediatric surgery were collected before and after gelatin infusion, and the osmolality was calculated by a modified version of Zander's formula.
In the in-vitro experiment, 65 gradually diluted blood samples from five volunteers (age 25-55 years) were analyzed. The dilution with gelatin caused no significant changes in osmolality between 0% and 100%. Compared with gelatin, the osmolality in the albumin group was significantly lower between 50% and 100% dilution (p < .05). In the in-vivo study, 221 children (age 21.4 ± 30 months) were included. After gelatin infusion, the osmolality increased significantly (mean change 4.3 ± 4.8 [95% CI 3.7-4.9] mosmol kg H O ; p < .01) within a normal range.
Gelatin in a balanced electrolyte solution has isotonic characteristics in-vitro and in-vivo, despite the low theoretical osmolarity, probably caused by the (unmeasured) negative charges in the gelatin molecules contributing to the plasma osmolality. For a better evaluation of the (real) tonicity of gelatin-containing solutions, we suggest to calculate the osmolality (mosmol kg H O ) using Zander's formula.
ClinicalTrials.gov (ID: NCT02495285).
围手术期输注治疗用的静脉输液应为等渗的，以维持儿童的体液内稳态。改良的胶体电解质溶液中的 4%明胶具有理论渗透压 284mosmol/L，实际渗透压 264mosmol/kgH2O。由于这两个值均低于 0.9%生理盐水或血浆，因此预计明胶在体外和体内都是低渗的。
我们假设明胶的输注预计会降低血浆渗透压。我们进行了一项体外实验和一项体内研究，以评估明胶对儿童渗透压的影响。
在体外实验中，将全血样本用 4%明胶或白蛋白（50g/L）从 0%（纯血）稀释至 100%（纯胶体），并通过冰点降低法测量渗透压。在体内研究中，收集行大型儿科手术的患儿的血气分析，在输注明胶前后进行，并通过修改后的赞德公式计算渗透压。
在体外实验中，分析了来自 5 名志愿者（年龄 25-55 岁）的 65 个逐渐稀释的血样。用明胶稀释不会导致渗透压在 0%和 100%之间发生显著变化。与明胶相比，白蛋白组在 50%至 100%稀释时渗透压明显较低（p<0.05）。在体内研究中，纳入了 221 名儿童（年龄 21.4±30 个月）。明胶输注后，渗透压显著升高（平均变化 4.3±4.8 [95%CI 3.7-4.9]mosmol/kgH2O；p<0.01），且处于正常范围内。
尽管理论渗透压较低，但平衡电解质溶液中的明胶在体外和体内均具有等渗特性，这可能是由于明胶分子中的（未测量到的）负电荷对血浆渗透压有贡献。为了更好地评估含明胶溶液的（实际）渗透压，我们建议使用赞德公式计算渗透压（mosmol/kgH2O）。
ClinicalTrials.gov（注册号：NCT02495285）。
