Sleep and Circadian Medicine Laboratory, Department of Physiology, Monash University, Melbourne, Australia.
School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, Australia.
Sleep. 2018 Nov 1;41(11). doi: 10.1093/sleep/zsy161.
Periodic breathing (PB) is common in newborns and is an obvious manifestation of ventilatory control instability. However, many infants without PB may still have important underlying ventilatory control instabilities that go unnoticed using standard clinical monitoring. Methods to detect infants with "subclinical" ventilatory control instability are therefore required. The current study aimed to assess the degree of ventilatory control instability using simple bedside recordings in preterm infants.
Respiratory inductance plethysmography (RIP) recordings were analyzed from ~20 minutes of quiet sleep in 20 preterm infants at 36 weeks post-menstrual age (median [range]: 36 [34-40]). The percentage time spent in PB was also calculated for each infant (%PB). Spontaneous sighs were identified and breath-by-breath measurements of (uncalibrated) ventilation were derived from RIP traces. Loop gain (LG, a measure of ventilatory control instability) was calculated by fitting a simple ventilatory control model (gain, time-constant, delay) to the post-sigh ventilatory pattern. For comparison, periodic inter-breath variability was also quantified using power spectral analysis (ventilatory oscillation magnitude index [VOMI]).
%PB was strongly associated with LG (r2 = 0.77, p < 0.001) and moderately with the VOMI (r2 = 0.21, p = 0.047). LG (0.52 ± 0.05 vs. 0.30 ± 0.03; p = 0.0025) and the VOMI (-8.2 ± 1.1 dB vs. -11.8 ± 0.9 dB; p = 0.026) were both significantly higher in infants that displayed PB vs. those without.
LG and VOMI determined from the ventilatory responses to spontaneous sighs can provide a practical approach to assessing ventilatory control instability in preterm infants. Such simple techniques may help identify infants at particular risk for ventilatory instabilities with concomitant hypoxemia and its associated consequences.
周期性呼吸（PB）在新生儿中很常见，是通气控制不稳定的明显表现。然而，许多没有 PB 的婴儿可能仍然存在重要的潜在通气控制不稳定，而这些不稳定在使用标准临床监测时可能会被忽略。因此，需要有检测具有“亚临床”通气控制不稳定的婴儿的方法。本研究旨在使用早产儿安静睡眠时的简单床边记录评估通气控制不稳定的程度。
对 36 周龄（中位数[范围]：36 [34-40]）胎龄的 20 名早产儿约 20 分钟的安静睡眠期间的呼吸感应体积描记（RIP）记录进行了分析。还计算了每个婴儿的 PB 时间百分比（%PB）。识别自发性叹息，并从 RIP 迹线逐呼吸测量（未经校准的）通气。通过拟合简单的通气控制模型（增益、时间常数、延迟）来计算环增益（LG，通气控制不稳定的度量），以适应叹息后的通气模式。为了比较，还使用功率谱分析（通气振荡幅度指数[VOMI]）量化了周期性呼吸间变异性。
%PB 与 LG 高度相关（r2 = 0.77，p < 0.001），与 VOMI 中度相关（r2 = 0.21，p = 0.047）。显示 PB 的婴儿的 LG（0.52 ± 0.05 与 0.30 ± 0.03；p = 0.0025）和 VOMI（-8.2 ± 1.1 dB 与-11.8 ± 0.9 dB；p = 0.026）均显著高于无 PB 的婴儿。
从自发叹息的通气反应中确定的 LG 和 VOMI 可为评估早产儿通气控制不稳定提供一种实用方法。这种简单的技术可能有助于识别具有潜在通气不稳定的婴儿，同时伴有低氧血症及其相关后果。
