Background

To present and evaluate a new respiratory level biofeedback system that aids the patient to return to a consistent breath-hold level with potential application in image-guided interventions.

Methods

The study was approved by the local ethics committee and written informed consent was waived. Respiratory motion was recorded in eight healthy volunteers in the supine and prone positions, using a depth camera that measures the mean distance to thorax, abdomen and back. Volunteers were provided with real-time visual biofeedback on a screen, as a ball moving up and down with respiratory motion. For validation purposes, a conversion factor from mean distance (in mm) to relative lung volume (in mL) was determined using spirometry. Subsequently, without spirometry, volunteers were given breathing instructions and were asked to return to their initial breath-hold level at expiration ten times, in both positions, with and without visual biofeedback. For both positions, the median and interquartile range (IQR) of the absolute error in lung volume from initial breath-hold were determined with and without biofeedback and compared using Wilcoxon signed rank tests.

Results

Without visual biofeedback, the median difference from initial breath-hold was 124.6 mL (IQR 55.7–259.7 mL) for the supine position and 156.3 mL (IQR 90.9–334.7 mL) for the prone position. With the biofeedback, the difference was significantly decreased to 32.7 mL (IQR 12.8–59.6 mL) (p < 0.001) and 22.3 mL (IQR 7.7–47.0 mL) (p < 0.001), respectively.

Conclusions

The use of a depth camera to provide visual biofeedback increased the reproducibility of breath-hold expiration level in healthy volunteers, with a potential to eliminate targeting errors caused by respiratory movement during lung image-guided procedures.

中文翻译：

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通过视觉生物反馈进行呼吸水平跟踪，以实现一致的屏气水平，并在图像引导干预中具有潜在的应用。

背景

提出并评估一种新的呼吸水平生物反馈系统，该系统可帮助患者恢复到一致的屏气水平，并在图像引导干预中具有潜在的应用。

方法

该研究得到了当地伦理委员会的批准，并放弃了书面知情同意书。使用深度相机记录八名健康志愿者仰卧和俯卧的呼吸运动，测量到胸部、腹部和背部的平均距离。志愿者在屏幕上获得实时视觉生物反馈，就像随着呼吸运动上下移动的球一样。出于验证目的，使用肺活量测定法确定从平均距离（以毫米为单位）到相对肺体积（以毫升为单位）的转换因子。随后，在没有肺活量测定的情况下，志愿者接受了呼吸指导，并被要求在有或没有视觉生物反馈的情况下在两种姿势下在呼气时恢复到最初的屏气水平十次。对于这两个位置，在有和没有生物反馈的情况下确定初始屏气肺容量绝对误差的中值和四分位距（IQR），并使用 Wilcoxon 符号秩检验进行比较。

结果

在没有视觉生物反馈的情况下，仰卧位与初始屏气的中位差异为 124.6 mL（IQR 55.7-259.7 mL），俯卧位为 156.3 mL（IQR 90.9-334.7 mL）。通过生物反馈，差异显着分别降至 32.7 mL (IQR 12.8–59.6 mL) ( p  < 0.001) 和 22.3 mL (IQR 7.7–47.0 mL) ( p  < 0.001)。

结论

使用深度相机提供视觉生物反馈，提高了健康志愿者屏气呼气水平的可重复性，有可能消除肺部图像引导手术期间呼吸运动引起的瞄准误差。