Nichols Robert H, Blinn Justin A, Ho Thuan M, McQuitty Robert A, Kinsky Michael P
The University of Texas Medical Branch at Galveston, Galveston, Texas.
Stanford University School of Medicine, Stanford, California.
Respir Care. 2018 Apr;63(4):448-454. doi: 10.4187/respcare.05723. Epub 2017 Dec 5.
The use of monitored anesthesia care for endoscopic procedures increases the risk of respiratory depression, necessitating careful monitoring of patient ventilation. We examined the effectiveness of an impedance-based respiratory volume monitor (RVM) in improving the safety of patients undergoing upper and lower gastrointestinal endoscopies under total intravenous anesthesia. We hypothesized that feedback from the RVM would allow anesthesiologists to maintain adequate ventilation, which would reduce the duration of respiratory depression (ie, hypoventilation and apnea) compared to a blinded control group.
Sixty-five subjects were enrolled in a randomized controlled trial and monitored with a noninvasive impedance-based RVM, which displayed respiratory traces and calculated expiratory minute ventilation (V̇), tidal volume (V), and breathing frequency (f) measurements. Prior to induction of anesthesia, a baseline V̇ measurement (V̇) was taken as a measurement of normal breathing. V̇ was monitored throughout the procedure for signs of hypoventilation and apnea. Hypoventilation was defined as V̇ < 40% V̇, and apneas were defined as V̇ = 0 for > 15 s.
Sixty-five subjects were randomly assigned to either a control ( = 38) or RVM intervention group ( = 27). Subjects in the intervention group had a higher V̇% for the entire procedure ( = .045), as well as the third and fourth quartile of the procedure compared to the control group ( = .01). Likewise, subjects in the RVM intervention group spent significantly less time below 40% V̇ compared to the control group throughout the entire procedure (12 ± 15% vs 32 ± 24%, respectively) ( < .001). The median number of apneas per subject was greater in the control group (median 2, interquartile range 1-2, maximum 4) compared to the RVM intervention group (median 1, interquartile range 1-2, maximum 3) ( = .037).
The control group had a higher incidence of hypoventilation and apnea compared to the RVM intervention group. Respiratory monitoring using the RVM can potentially be a useful tool for identifying early signs of respiratory depression and for titrating anesthetics to maintain adequate ventilation while minimizing patient risk.
在内镜检查过程中使用监护麻醉会增加呼吸抑制的风险，因此需要对患者的通气情况进行仔细监测。我们研究了基于阻抗的呼吸容量监测仪（RVM）在提高接受全静脉麻醉的上消化道和下消化道内镜检查患者安全性方面的有效性。我们假设，与盲目对照组相比，RVM的反馈将使麻醉医生能够维持足够的通气，从而缩短呼吸抑制（即通气不足和呼吸暂停）的持续时间。
65名受试者参加了一项随机对照试验，并用基于阻抗的无创RVM进行监测，该监测仪可显示呼吸轨迹并计算呼气分钟通气量（V̇）、潮气量（V）和呼吸频率（f）测量值。在麻醉诱导前，测量一次基线V̇测量值（V̇）作为正常呼吸的测量值。在整个手术过程中监测V̇，以观察通气不足和呼吸暂停的迹象。通气不足定义为V̇ < 40%V̇，呼吸暂停定义为V̇ = 0持续超过15秒。
65名受试者被随机分配到对照组（n = 38）或RVM干预组（n = 27）。与对照组相比，干预组受试者在整个手术过程中的V̇%更高（P = .045），在手术的第三个和第四个四分位数期间也是如此（P = .01）。同样，在整个手术过程中，RVM干预组的受试者低于40%V̇的时间明显少于对照组（分别为12 ± 15%和32 ± 24%）（P < .001）。对照组中每位受试者的呼吸暂停中位数（中位数为2，四分位数间距为1 - 2，最大值为4）高于RVM干预组（中位数为1，四分位数间距为1 - 2，最大值为3）（P = .037）。
与RVM干预组相比，对照组通气不足和呼吸暂停的发生率更高。使用RVM进行呼吸监测可能是一种有用的工具，可用于识别呼吸抑制的早期迹象，并调整麻醉剂量以维持足够的通气，同时将患者风险降至最低。
