Locke R G, Wolfson M R, Shaffer T H, Rubenstein S D, Greenspan J S
Department of Physiology, Temple University School of Medicine, Philadelphia, PA.
Pediatrics. 1993 Jan;91(1):135-8.
In the clinical setting, nasal cannulas are frequently used to deliver supplemental oxygen to neonates and are not believed to affect the general respiratory status. In contrast, it was hypothesized that clinical changes associated with nasal cannula gas flow may be related in part to the generation of positive end-distending pressure. To test this hypothesis, alterations in esophageal pressure were quantified as an indication of end-distending pressure and thoracoabdominal motion was quantified as an indication of breathing patterns in 13 preterm infants at gas flow levels of 0.5, 1, and 2 L/min delivered by nasal cannula with an outer diameter of either 0.2 or 0.3 cm. Changes in esophageal pressure were assessed by esophageal balloon manometry. Ventilatory patterns were assessed from thoracoabdominal motion by using respiratory inductive plethysmography. Thoracoabdominal motion was quantitated as a phase angle (theta); larger values represent greater asynchrony. The 0.2-cm nasal cannula did not deliver pressure or alter thoracoabdominal motion at any flow. In contrast, the 0.3-cm nasal cannula delivered positive end-distending pressure as a function of increasing levels of gas flow (r = .92) and reduced thoracoabdominal motion asynchrony. The mean pressure generated at 2 L/min was 9.8 cm H2O. These data demonstrate that nasal cannula gas flow can deliver positive end-distending pressure to infants and significantly alter their breathing strategy. This finding raises important concerns about the indiscriminate therapeutic use, size selection, and safety of nasal cannulas for the routine delivery of oxygen in preterm infants.
在临床环境中，鼻导管经常用于为新生儿输送补充氧气，且人们认为它不会影响总体呼吸状态。相比之下，有假设认为，与鼻导管气流相关的临床变化可能部分与呼气末正压的产生有关。为了验证这一假设，对13名早产儿在通过外径为0.2或0.3厘米的鼻导管以0.5、1和2升/分钟的气流水平输送气体时的食管压力变化进行了量化，以此作为呼气末压力的指标，同时对胸腹运动进行了量化，以此作为呼吸模式的指标。通过食管气囊测压法评估食管压力的变化。使用呼吸感应体积描记法根据胸腹运动评估通气模式。胸腹运动被量化为一个相角（θ）；值越大表示异步性越大。0.2厘米的鼻导管在任何气流水平下都不会产生压力或改变胸腹运动。相比之下，0.3厘米的鼻导管随着气流水平的增加而产生呼气末正压（r = 0.92），并减少了胸腹运动的异步性。在2升/分钟时产生的平均压力为9.8厘米水柱。这些数据表明，鼻导管气流可以给婴儿输送呼气末正压，并显著改变他们的呼吸策略。这一发现引发了人们对鼻导管在早产儿常规输氧中的随意治疗用途、尺寸选择和安全性的重要担忧。
