Recognizing nonerosive reflux disease (NERD) as a distinct presentation of gastroesophageal reflux disease (GERD) was one of the most important developments in the field of GERD in the last decade. Whilst the definition of NERD has not changed significantly over the years, the disorder accounts for the majority of the GERD patients and those who failed proton pump inhibitor (PPI) treatment. Recent developments in NERD focused primarily on understanding the pathophysiology and natural history. The introduction of esophageal impedance + pH has led to the assessment of other forms of gastroesophageal reflux in causing NERD. Therapeutic modalities still focus on acid suppression, but there is growing recognition that other therapeutic strategies should be considered in NERD.

Correspondence 823 Pethidine, metoclopramide and the gnstro-oesophageal sphincter Gastro-oesophageal reflux after pethidine? We were interested to read the paper by Hey ef al. (Anaesthesia 1981; 3 6. 173-6) but feel that they have failed to provide direct support for their suggestion that pethidine increases the possibility of gastro-oesopha-geal reflux, and that metoclopramide is a useful adjunct in the prevention of reflux in patients receiving pethi-dine. Their study would have been much more valuable if they had actually demonstrated acid reflux which can be easily done with an intra-oesophageal pH probe at the same time as manometric measurements. They have demonstrated lowering of lower oesophageal sphincter (LOS) pressure with pethidine and conclude that this must lead to the increased possibility of reflux because a study of Hall et a1.l quoted by them suggested that this was so. However, in contrast, atropine is also known to lower LOS pressure in man2 but it does not increase epidsodes of acid reflux.) It is true that Hall et aZ.I did find some correlation between gastro-oesophageal re-flux and lowering of the LOS pressure, this has not been the finding of other workers and there is a considerable overlap between the LOS pressure in those who reflux and the pressure in those who do not."7 Indeed Bennett6 showed that individuals with a LOS pressure as low as 8 cmH2O may not reflux whereas those with a LOS pressure as high as 32 cmHzO do. There is, therefore, a lack of precise correlation between LOS pressure and the presence or absence of reflux. This is probably related, in part, to the problem of determining a pressure reading from what is not a single pressure but a group of varying pressures which depend on the position of the manometric probe in the moreover the LOS does not have a static of fixed pressure, and it varies considerably with mechanical stress, hormonal factors, and even emotional fac-It is unwise to imply that lowering the LOS pressure with pethidine is likely to lead to reflux without demonstrating acid reflux into the oesophagus, and it is even more unwise to assume that, because metoclopra-mide appears to oppose the effect of pethidine on LOS pressure, it actually would prevent any gastro-oesopha-geal reflux that might occur. DB. The effects of premedication drugs on the lower oesophageal high pressure zone acid and reflux status of Rhesus monkeys and man. Gut 1975; 1 6 347-52. 2. LIND JS, CRISPIN JS, MCIWR DK. The effect ofatropine on the gastroesophageal sphincter. Canadian Journal of Physiology and Pharmacology 1968; 46.233-8. 3. SKINNER DB, CAMP TF. Relation of esophageal reflux to lower esophageal sphincter pressures decreased by atro-pine. Gastroenterology 1968; 54: 543-51. 4. POPE CE. A dynamic test of sphincter strength: its application to the lower esophageal sphincter. Gastroenterology 1967; 5 2 779-86. 5. HADDAD JK. Relation of gastroesophageal reflux to yield sphincter pressures. Gastroenterology 1970; 58: 175-84. 6. BENNETT JR. The physician's problem. Gut 1973; 14: 24...

Management of refractory GERD patients remains an important clinical challenge. Recent studies have cemented the value of impedance-pH testing in pursuing proper treatment. Presently, the most promising therapeutic development for this patient population is transient lower esophageal sphincter relaxation reducers.