Department of Veterinary Surgery and Animal Reproduction, Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista (UNESP), Botucatu, SP, Brazil.
Department of Veterinary Surgery and Animal Reproduction, Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista (UNESP), Botucatu, SP, Brazil; Department of Anesthesiology, Faculdade de Medicina, Universidade Estadual Paulista (UNESP), Botucatu, SP, Brazil.
Vet Anaesth Analg. 2021 Mar;48(2):187-197. doi: 10.1016/j.vaa.2020.12.006. Epub 2021 Jan 12.
To evaluate the ability of transthoracic echocardiographic aortic flow measurements to discriminate response to a fluid challenge (FC) in healthy anesthetized dogs.
Prospective experimental study.
A total of 48 isoflurane-anesthetized dogs (14.2-35.0 kg) undergoing elective surgery.
Fluid responsiveness was evaluated before surgery by FC (lactated Ringer's 10 mL kg intravenously over 5 minutes). Percentage increases in transpulmonary thermodilution stroke volume (ΔSV) >15% from values recorded before FC defined responders to volume expansion. A group of 24 animals were assigned as nonresponders (ΔSV ≤15%). When ΔSV was >15% after the first FC, additional FC were administered until ΔSV was ≤15%. Final fluid responsiveness status was based on the response to the last FC. Percentage increases after FC in aortic flow indexes [velocity time integral (ΔVTI) and maximum acceleration (ΔVmax)] and in mean arterial pressure (ΔMAP) were compared with ΔSV.
After one FC, 24 animals were responders. For nonresponders, ΔSV was ≤15% after one, two and three FCs in eight/24, 15/24 and one/24 animals, respectively. The FC that defined responsiveness increased ΔSV by 29 (18-53)% in responders and by 8 (-3 to 15)% in nonresponders [mean (range)]. The area under the receiver operating characteristics curve (AUROC) of ΔVTI (0.901) was larger than the AUROCs of ΔVmax (0.774, p = 0.041) and ΔMAP (0.519, p < 0.0001). ΔMAP did not predict responsiveness (p = 0.826). Best cut-off thresholds for discriminating responders, with respective zones of diagnostic uncertainty (gray zones) were >14.7 (10.8-17.6)% for ΔVTI and >8.6 (-0.3 to 14.7)% for ΔVmax. Animals within the gray zone were 17% (ΔVTI) and 50% (ΔVmax).
Changes in VTI induced by FC can determine responsiveness with reasonable accuracy in dogs and could play an important role in goal-directed fluid therapy.
评估经胸超声心动图主动脉血流测量在健康麻醉犬中对液体反应的能力。
前瞻性实验研究。
共 48 只异氟醚麻醉犬（14.2-35.0 公斤）接受择期手术。
在手术前通过 FC（静脉内给予 10 毫升/公斤乳酸林格氏液，持续 5 分钟）评估液体反应性。从 FC 前记录的值中，SV 增加超过 15%的百分比定义为对容量扩张有反应。一组 24 只动物被分配为无反应者（SV 增加≤15%）。如果第一次 FC 后 SV 增加超过 15%，则给予额外的 FC，直到 SV 增加≤15%。最终的液体反应性状态基于对最后一次 FC 的反应。与 SV 相比，比较 FC 后主动脉血流指数[速度时间积分（ΔVTI）和最大加速度（ΔVmax）]和平均动脉压（ΔMAP）的增加百分比。
一次 FC 后，24 只动物为反应者。对于无反应者，8/24、15/24 和 1/24 只动物在一次、两次和三次 FC 后，SV 分别增加≤15%。定义反应性的 FC 将 SV 增加 29%（18-53%），而无反应者增加 8%（-3 至 15%）[平均值（范围）]。VTI 的接收者操作特征曲线（AUROC）面积（0.901）大于 Vmax 的 AUROC（0.774，p=0.041）和 MAP 的 AUROC（0.519，p<0.0001）。MAP 不能预测反应性（p=0.826）。用于区分反应者的最佳截断阈值（具有相应的诊断不确定区域（灰色区域））分别为>14.7%（10.8-17.6%）用于 VTI 和>8.6%（-0.3 至 14.7%）用于 Vmax。在灰色区域内的动物占 17%（VTI）和 50%（Vmax）。
FC 引起的 VTI 变化可以在犬中以合理的准确度确定反应性，并且在目标导向性液体治疗中可能发挥重要作用。
