Department of Intensive Care Medicine, Radboud University Nijmegen Medical Centre, Internal Mail 685, Geert Grooteplein 10, 6500 HB Nijmegen, The Netherlands.
Clin Sci (Lond). 2011 Sep;121(5):215-22. doi: 10.1042/CS20110027.
HRV (heart rate variability) analysis is a widely employed method to assess cardiac autonomic nervous system activity. Accurate HRV measurement is critical to its value as a diagnostic and prognostic tool. Different breathing patterns may affect HRV, but results obtained under static conditions are conflicting. HRV indices decrease considerably during systemic inflammation evoked by experimental endotoxaemia, enabling the determination of the effects of different breathing patterns on HRV in a dynamic setting. We investigated the impact of different breathing patterns on short-term HRV measurements during experimental endotoxaemia. Furthermore, we assessed whether paced breathing improved HRV reproducibility. Twelve healthy male volunteers received an intravenous bolus (2 ng/kg of body weight) of endotoxin [LPS (lipopolysaccharide), derived from Escherichia coli O:113] on two occasions with an interval of 2 weeks. Five-minute HRV recordings were performed just prior to LPS administration and hourly thereafter until 8 h post-LPS. Three breathing protocols were employed every hour: (i) spontaneous breathing, (ii) metronome-guided breathing at the subject's normal respiratory rate ('paced') and (iii) metronome-guided breathing at 150% of the subject's normal respiratory rate ('mild hyperventilation'). LPS administration resulted in a sharp decrease in all of the HRV indices measured, which was similar during both LPS administrations. Neither paced breathing nor mild hyperventilation influenced HRV indices compared with spontaneous breathing. Paced breathing did not improve reproducibility as it did not exert a significant effect on intra-subject coefficients of variation and intra-class correlation coefficients (calculated between both visits). In conclusion, over a wide range of HRV magnitudes during experimental endotoxaemia, neither paced breathing nor mild hyperventilation affected HRV indices. Moreover, paced breathing did not result in a significant improvement in reproducibility. Therefore employing a paced breathing protocol is not required to obtain valid HRV data during endotoxaemia.
心率变异性（HRV）分析是评估心脏自主神经系统活动的一种广泛应用的方法。准确的 HRV 测量对于其作为诊断和预后工具的价值至关重要。不同的呼吸模式可能会影响 HRV，但静态条件下的结果存在冲突。在实验性内毒素血症引起的全身炎症期间，HRV 指数会显著下降，这使得能够在动态环境中确定不同呼吸模式对 HRV 的影响。我们研究了不同呼吸模式对内毒素血症实验中短期 HRV 测量的影响。此外，我们评估了有节奏的呼吸是否能提高 HRV 的可重复性。12 名健康男性志愿者在 2 周的间隔内两次接受静脉内推注（2ng/kg 体重）内毒素[脂多糖（LPS），源自大肠杆菌 O：113]。在 LPS 给药前和给药后每小时进行 5 分钟的 HRV 记录，直到 LPS 给药后 8 小时。每小时采用三种呼吸方案：（i）自然呼吸，（ii）以受试者正常呼吸频率为指导的节拍器呼吸（“有节奏的”）和（iii）以受试者正常呼吸频率的 150%为指导的节拍器呼吸（“轻度过度通气”）。LPS 给药导致所有测量的 HRV 指数急剧下降，两次给药时相似。与自然呼吸相比，有节奏的呼吸或轻度过度通气均未影响 HRV 指数。与自然呼吸相比，有节奏的呼吸并没有改善可重复性，因为它对内源性变异系数和组内相关系数（两次就诊之间计算）没有显著影响。总之，在实验性内毒素血症期间，HRV 幅度较宽的范围内，有节奏的呼吸或轻度过度通气均未影响 HRV 指数。此外，有节奏的呼吸并没有导致可重复性的显著改善。因此，在发生内毒素血症时，不需要采用有节奏的呼吸方案来获得有效的 HRV 数据。
