Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
Vet Anaesth Analg. 2020 May;47(3):356-367. doi: 10.1016/j.vaa.2020.01.004. Epub 2020 Feb 8.
To evaluate the equipment used for nasal insufflation of oxygen and determine its accuracy.
Original study.
Oxygen delivery assemblies consisting of a flowmeter, bubble humidifier, oxygen delivery tubing and nasal insufflation catheters were assembled. Single and double catheter assemblies were made for four sizes of nasogastric feeding tubes (3.5 Fr, 5.0 Fr, 8.0 Fr and 10.0 Fr) resulting in 64 individual assemblies. A gas flow analyzer measured oxygen flow at the tip of the nasal catheter assemblies and from the pressure relief valve (PRV) of the bubble humidifiers. Statistical analyses were conducted to assess the functionality of assemblies. For functional assemblies, the accuracy of oxygen flow relative to the prescribed flow settings was determined.
Catheter size was significantly associated with the functionality of assemblies. Probability (95% confidence interval) of 3.5 Fr, 5.0 Fr and 8.0 Fr assemblies being functional was estimated at 0.53 (0.14, 0.89), 0.83 (0.36, 0.98) and 0.98 (0.76, 0.99), respectively. All 10.0 Fr assemblies were functional. Functional assemblies, in general, consistently under-delivered the prescribed flow because a large portion of set flow was diverted through the bubble humidifier PRV.
Leaks through the PRV cause significant diversion of oxygen prior to it reaching the catheter tips. Smaller patients are particularly susceptible, as small catheters limit oxygen delivery creating proportionally greater leaks through the PRV.
It was not possible to accurately deliver oxygen because of leaks through the PRV. Targeting a specific outcome (e.g., oxyhemoglobin saturation > 94%, PaO 80-120 mmHg; 11-16 kPa) and avoiding unnecessarily high fractions of inspired oxygen cannot be done if flow delivery cannot be accurately assured. One possible solution would be to use a bubble humidifier with a 6 psi PRV that does not leak prior to reaching the opening pressure.
评估用于鼻内给氧的设备并确定其准确性。
原始研究。
组装由流量计、气泡式湿化器、给氧管和鼻内给氧导管组成的给氧装置。为 4 种规格的鼻胃管（3.5Fr、5.0Fr、8.0Fr 和 10.0Fr）制作单导管和双导管组件，共 64 个组件。气体流量分析仪测量鼻导管组件尖端和气泡式湿化器减压阀（PRV）的氧气流量。进行统计学分析以评估组件的功能。对于功能组件，确定相对于规定流量设置的氧气流量的准确性。
导管尺寸与组件的功能显著相关。3.5Fr、5.0Fr 和 8.0Fr 组件的功能概率（95%置信区间）估计分别为 0.53（0.14，0.89）、0.83（0.36，0.98）和 0.98（0.76，0.99）。所有 10.0Fr 组件均具有功能。功能组件通常会输送低于规定流量的氧气，因为大部分设定流量会通过气泡式湿化器 PRV 分流。
PRV 泄漏会导致氧气在到达导管尖端之前大量分流。较小的患者尤其容易受到影响，因为较小的导管限制了氧气输送，从而导致通过 PRV 的泄漏比例更大。
由于 PRV 泄漏，无法准确输送氧气。如果无法准确保证流量输送，则无法针对特定目标（例如，氧合血红蛋白饱和度>94%，PaO 80-120mmHg；11-16kPa）并避免不必要地高吸入氧分数。一个可能的解决方案是使用在到达开启压力之前不会泄漏的具有 6psi PRV 的气泡式湿化器。
