Fletcher J, Wirz A, Henry E, McColl K E L
Department of Medicine and Therapeutics, Gardiner Institute, Western Infirmary, University of Glasgow, Glasgow G11 6NT, Scotland, UK.
Gut. 2004 Feb;53(2):168-73. doi: 10.1136/gut.2003.022160.
Oesophageal pH is conventionally recorded from a point 5 cm above the lower oesophageal sphincter. However, the mucosal changes of reflux oesophagitis and intestinal metaplasia tend to affect the segment of oesophagus distal to this and close to the squamocolumnar junction. This study set out to investigate oesophageal acid exposure of squamous mucosa close to the squamocolumnar junction.
Dual channel 24 hour pH monitoring was carried out in 11 patients with endoscopy negative dyspepsia and no evidence of gastro-oesophageal reflux by conventional oesophageal pH metry. Oesophageal pH was recorded from electrodes positioned 5 mm and 55 mm proximal to the squamocolumnar junction. A novel technique was developed using metal clips to secure the pH catheter to the oesophageal mucosa and maintain these electrode positions. Oesophageal manometry indicated that the distal electrode was within the high pressure zone of the lower oesophageal sphincter.
We found that 24 hour oesophageal acid exposure (per cent time pH <4) was greater 5 mm above the squamocolumnar junction compared with the conventional position 5 cm more proximal (11.7% v 1.8%; p<0.001). The greater acid exposure at the distal versus the conventional site was apparent in both the upright (12.7% v 2.3%) and supine (10.5% v 1.3%) positions, as well as during preprandial (14.2% v 1.6%) and postprandial (21.8% v 2.8%) periods (p<0.001 for each). The number of reflux events recorded close to the squamocolumnar junction was also higher than at the conventional position (168 v 33; p<0.001). There was no correlation between acid exposure at the two sites.
The squamous mucosa of the most distal oesophagus is exposed to substantial acidic reflux, even in patients without evidence of conventional reflux disease. This short segment reflux may explain the high incidence of metaplasia and neoplasia at the gastro-oesophageal junction.
传统上，食管pH值是在下食管括约肌上方5厘米处记录的。然而，反流性食管炎和肠化生的黏膜变化往往会影响该部位远端且靠近鳞柱状上皮交界处的食管段。本研究旨在调查靠近鳞柱状上皮交界处的鳞状黏膜的食管酸暴露情况。
对11例内镜检查阴性的消化不良患者进行双通道24小时pH监测，且通过传统食管pH测量法未发现胃食管反流迹象。食管pH值是从位于鳞柱状上皮交界处近端5毫米和55毫米处的电极记录的。开发了一种新技术，使用金属夹将pH导管固定在食管黏膜上并维持这些电极位置。食管测压表明远端电极位于下食管括约肌的高压区内。
我们发现，与近端5厘米处的传统位置相比，在鳞柱状上皮交界处上方5毫米处的24小时食管酸暴露（pH值<4的时间百分比）更高（11.7%对1.8%；p<0.001）。在直立位（12.7%对2.3%）、仰卧位（10.5%对1.3%）以及餐前（14.2%对1.6%）和餐后（21.8%对2.8%）期间，远端部位的酸暴露均明显高于传统部位（各p<0.001）。在靠近鳞柱状上皮交界处记录的反流事件数量也高于传统位置（168对33；p<0.001）。两个部位的酸暴露之间无相关性。
即使在没有传统反流疾病证据的患者中，食管最远端的鳞状黏膜也会暴露于大量酸性反流中。这种短段反流可能解释了胃食管交界处化生和肿瘤形成的高发生率。
