Objective definition and detection of transient lower esophageal sphincter relaxation revisited: is there room for improvement?

BACKGROUND: The advent of drugs that inhibit transient lower esophageal sphincter relaxation (TLESR) necessitates accurate identification and scoring. We assessed the intra- and inter-assessor variability of the existing objective criteria for TLESR, improving them where necessary. METHODS: Two 3-h postprandial esophageal manometric and pH recordings were performed in 20 healthy volunteers. Each recording was duplicated. The recordings were analyzed by five experienced observers for TLESRs based on their expert opinion. TLESRs were also analyzed for the presence of the original four criteria as well as inhibition of the crural diaphragm (ID), a prominent after-contraction (AC), acid reflux and an esophageal common cavity. KEY RESULTS: The overall inter- and intra-observer agreements for TLESRs scored, according to observer's expert opinion, were 59% (range 56-67%) and 74% (60-89%), respectively. When TLESRs were restricted to those fulfilling the original criteria, these agreements fell to 46% (40-53%) and 60% (44-67%), respectively. Cleaning the recordings by removal of technically flawed sections improved agreements by 5%. Inclusion of additional criteria (ID and AC) resulted in inter- and intra-observer agreements of 62% (52-70%) and 69% (53-79%), respectively. A consensus analysis performed collectively by three observers and based on the new criteria (original ± ID and AC) resulted in 84% agreement between the paired recordings. CONCLUSIONS & INFERENCES: The original criteria for the definition of TLESRs allows for substantial inter- and intra-observer variability, which can be reduced by incorporation of additional objective criteria. However, the highest level of intra-observer agreement can be achieved by consensus analysis.

Neural regulation of tone in the oesophageal body: in vivo barostat assessment of volume-pressure relationships in the feline oesophagus.

Recent combined manometric-barostat studies demonstrated that the oesophageal body exhibits both peristaltic contractions and tone. This study further characterized the neural modulation of tone in the feline oesophageal body. Simultaneous oesophageal barostat and manometry were performed in 20 adult cats under ketamine sedation. Oesophageal tone and peristalsis were assessed in the distal smooth muscle oesophagus. Cholinergic modulation was studied using neostigmine, erythromycin, atropine and vagotomy. Nitrergic regulation was assessed using sildenafil to increase cellular cyclic guanosine monophosphate and the nitric oxide synthase blocker Nomega-nitro-l-arginine (l-NNA). The presence of a tonic contractile activity in the distal oesophageal body was confirmed. Peristaltic contractions proceeded along the oesophageal body over the background tonic contraction. Neostigmine and erythromycin enhanced (20-30%) whereas bilateral vagotomy and atropine strongly decreased oesophageal tone (50-60%). However, l-NNA increased (40%) and sildenafil decreased oesophageal tone (30%). Therefore, tonic contractile activity in the oesophageal body is mainly caused by a continuous cholinergic excitatory input. A nitric oxide inhibitory mechanism may have a complementary role in the regulation of oesophageal tone.

Effect of sildenafil, a phosphodiesterase-5 inhibitor, on oesophageal peristalsis and lower oesophageal sphincter function in cats.

The propagation of oesophageal peristaltic contractions and lower oesophageal sphincter (LOS) relaxation depends on neural release of nitric oxide (NO) which acts to increase intracellular cGMP. Sildenafil, a phosphodiesterase-5 inhibitor that increases cGMP, reduces basal LOS pressure in patients with achalasia. We investigated the effect of sildenafil on the propagation of oesophageal contractions and LOS relaxation in the cat. Oesophageal manometry was performed in five cats under light sedation. Peristaltic contractions were monitored at 1, 2, 3, 4 and 8 cm proximal to the LOS, at the LOS using a Dent sleeve, and at 3 cm distal to the upper oesophageal sphincter. Swallow-induced oesophageal contractions and LOS relaxation were recorded during 30 min before and 30 min after intravenous administration of sildenafil. Sildenafil reduced the amplitude of oesophageal contractions only in the smooth muscle oesophagus. The latency from swallow to distal oesophageal contractions was significantly delayed. LOS pressure was significantly reduced but the relaxation nadir was not modified by sildenafil. Sildenafil has profound effects on oesophageal motility: it modifies propagation and amplitude of oesophageal contractions and reduces LOS pressure. Slowing down the propagation of contractions in the transitional zone between the striated and smooth muscle can be a useful tool in patients with segmental aperistalsis or intermittent simultaneous contractions, while the effect on the LOS can benefit patients with achalasia.

The 'artificial high pressure zone'. A non-invasive method to study in man the effect of the inhibitory innervation to the oesophagus. Validation study using a combined manometric--barostat technique.

OBJECTIVE: We previously developed a technique to study the effect of inhibitory innervation in the human oesophageal body, by creating an artificial high pressure zone (artificial HPZ) using an intra-oesophageal balloon. Swallowing provokes a fall in pressure in the artificial HPZ that precedes the peristaltic contraction. We aimed to prove that the swallow-induced fall in pressure in the artificial HPZ is due to relaxation of a segmental tonic contraction of the oesophageal wall at that level. METHODS: Studies were performed in five healthy subjects. Oesophageal pressures were measured at 5, 10 and 15 cm above the lower oesophageal sphincter. A rubber balloon opposite the middle pressure sensor was used to induce the artificial HPZ. A barostat bag was glued to the opposite side of the balloon. The pressure in the barostat bag was pre-set at 8 mmHg below the pressure measured in the artificial HPZ. We studied deglutition-induced variations in the barostat bag volume after single and multiple swallows. RESULTS: Immediately after single swallows and during multiple swallows, we observed a fall in pressure in the artificial HPZ and a significant increase in the barostat bag volume (254+/-67%) from 0.99 (0.37-1.93) to 3.74 (1.91-4.34) (P = 0.005) denoting oesophageal wall relaxation. CONCLUSION: The swallow-induced fall in pressure in the artificial HPZ represents a real relaxation of a segmental tonic contraction of the oesophageal wall due to deglutitive inhibition. The oesophageal artificial HPZ is a simple method that can be used to study inhibitory phenomena in the body of the human oesophagus.