Effects of sevoflurane and enflurane on lower esophageal sphincter pressure and gastroesophageal pressure gradient in children

Purpose. The effects of sevoflurane and enflurane on the intraluminal pressure of the lower esophagus (LE), lower esophageal sphincter (LES), and stomach were investigated in paralyzed and mechanically ventilated children under general anesthesia. Methods. A total of 14 children, ASA physical status class I without risk factors for regurgitation, scheduled for orthopedic surgery were studied. After induction of anesthesia, we inserted a gastrointestinal pressure sensor nasally and monitored the intraluminal pressure of the LE, LES, and stomach under various concentrations of sevoflurane or enflurane with 66% nitrous oxide in oxygen prior to surgical incision. The barrier pressure (BrP), which is the difference between LES pressure and intragastric pressure, was calculated. Results. Sevoflurane at 2.0 and 2.5 minimum alveolar concentration (MAC) decreased LES pressure, and enflurane at 2.0 and 2.5 MAC decreased both LES pressure and BrP in anesthetized children. The intraluminal pressure of the LE and stomach were not altered in either group. Conclusion. Sevoflurane and enflurane have an inhibitory effect on LES smooth muscle in anesthetized children. However, since the reduction was relatively low, even at high concentrations, these inhalation anesthetics are unlikely to influence gastroesophageal reflux during anesthesia. Received for publication on April 16, 1998; accepted on July 21, 1998     

Effect of hyperparathyroidism and hypercalcemia on lower esophageal sphincter pressure

Heartburn is a frequent and sometimes initial complaint in hyperparathyroidism, and it is often relieved by successful parathyroid surgery. Four of five patients with primary hyperparathyroidism and heartburn obtained relief of symptoms and had an increase in lower esophageal sphincter pressure after successful operative treatment. Four of five volunteers undergoing calcium infusion exhibited a decrease in lower esophageal sphincter pressure after about 2.5 to 3 hours of infusion. Calcium infusion in a treated patient who had an increase in lower esophageal sphincter pressure postoperatively resulted in a transient return of lower esophageal sphincter pressure to preoperative levels.     

七氟醚对小儿食管下段括约肌功能的影响

目的　观察七氟醚麻醉对小儿食管下段括约肌 (LES)功能的影响。方法　 15例行择期手术小儿 ,年龄 3～ 7岁 ,ASAⅠ～Ⅱ级 ,术前无胃食管反流症状 ,亦未用术前药。静脉注射γ 羟基丁酸钠和阿曲库铵诱导插管后 ,吸入七氟醚维持麻醉。吸入前及吸入浓度分别达 0 5、1 0和1 5MAC时 ,用PaPolygrafHR胃肠动力监测系统进行测压。用专业软件处理、储存下列数据 :LES压力 (LESP)、胃压 (GP)、屏障压 (BrP)、长度 (SL)、压力向量容积 (PVV)。结果　随七氟醚MAC的升高 ,LESP、BrP和PVV均有所下降 ,与基础值相比 ,0 5MAC和 1 0MAC时差异无显著意义 (P >0 0 5 ) ;1 5MAC时差异有显著性意义 (P <0 0 5 )。而SL和GP无明显变化。结论　七氟醚对小儿LES功能的影响较小 ,有利于维持其功能稳定。但有高度反流危险的小儿 ,应避免使用高浓度七氟醚     

Reduction of lower esophageal sphincter pressure with Stamm gastrostomy

Although recent clinical studies suggest an association between Stamm gastrostomy and gastroesophageal reflux (GER), no significant experimental data is available. This study evaluates alterations in lower esophageal sphincter (LES) pressure after Stamm gastrostomy in cats. Eight male cats (average weight 3 to 4 kg) were induced under general anesthesia using 20/mg/kg ketamine intramuscularly (IM). Esophageal manometrics were determined for each animal using a continuous perfusion catheter and recording system. Three measurements were taken for each animal. Stamm gastrostomy was then placed in the anterior wall of the stomach two thirds of the way down from the fundus. This was tacked to the anterior abdominal wall 3.0 cm lateral to the midline at the appropriate longitudinal level. Esophageal manometry was repeated after abdominal closure. The animals were awakened and returned to their cages for ad libidum feedings. The animals were reanesthetized with ketamine and manometrics repeated at 7 and 14 days. Each animal served as its own control. Five animals underwent barium esophagram 14 days postoperatively to evaluate for GER. Preoperative mean LES pressure measured 11.4 +/- 3.5 torr. This decreased to 7.8 +/- 2.8 torr immediately after Stamm gastrostomy (P less than .025). When evaluated at 1 and 2 weeks after gastrostomy, further decrease in LES pressures to 6.6 +/- 1.6 torr and 4.8 +/- 1.6 was observed (P less than .02 v preoperative). Three of five cats undergoing barium swallow demonstrated significant reflux radiographically. Stamm gastrostomy caused significant reduction of the LES pressure in all cats studied. This resulted in clinical GER as documented by barium swallow in three of five cats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of hemorrhagic hypotension and hypoventilation on lower esophageal sphincter pressure.

Dysfunction of the lower esophageal sphincter has been demonstrated in the cat shock model. Analogies have been drawn to reflux and aspiration in the critically ill patient. In a cat shock model, lower esophageal sphincter pressure is reduced and response to bethanechol is impaired. Upon resuscitation to basal state with heparinized shed blood, the lower esophageal basal pressure returns to normal values, and response to bethanechol is restored. This model may explain reflux and aspiration in the critically ill patient.     

The role of motilin and cisapride in the enteric nervous system of the lower esophageal sphincter in humans

To assess the pharmacophysiological significance of the enteric nervous system and the responses of the human lower esophageal sphincter (LES) to motilin and cisapride, the mechanical responses of esophgeal tissues from six patients with esophageal cancer and seven patients with gastric cancer were investigated. Circular muscle reactions were recorded to evaluate the in vitro esophageal responses to electrical field stimulation (EFS), motilin, and cisapride, evoking the adrenergic and cholinergic nerves before and after treatment with various autonomic nerve blockers. The findings of this study revealed that: cholinergic nerves are mainly involved in the regulation of enteric nerves in the steady state, while nonadrenergic non-cholinergic (NANC) inhibitory nerves also exist; motilin may act both via nerves and also directly on the LES smooth muscle; and cisapride releases acetylcholine from the end of the postganglionic fiber of the cholinergic nerve in human LES thereby inducing contraction of the LES. These results suggest that cholinergic and NANC inhibitory nerves play an important role in human LES, and that motilin and cisapride is clinically useful for improving the impaired LES of patients with gastroesophageal reflux. Part of this work was presented at the 15th Annual Conference of Gut Hormones held on July 21, 1994, in Shizuoka, Japan.     

地氟醚与安氟醚对小儿食管下段括约肌功能的影响

目的观察地氟醚与安氟醚麻醉对小儿食管下段括约肌(LES)功能的影响.方法26例行择期手术小儿,年龄3～7岁,ASAⅠ～Ⅱ级,术前无胃食管反流症状,亦未用术前药.静脉注射羟丁酸钠和阿曲库铵诱导插管后,随机分为地氟醚(D组)和安氟醚(E组)两组.在吸入地氟醚与安氟醚前以及当其吸入浓度分别达到0.5MAC、1.0MAC、1.5MAC时,用PaPolygraf HR胃肠动力监测系统测定下列数据LES压力(LESP)、胃压(GP)、屏障压(BrP)、长度(SL)、压力向量容积(PVV)和向量容积的三维立体图象.结果随地氟醚或安氟醚MAC的升高,D组各项指标与吸入前相比无明显变化(P＞0.05);而E组的LESP、BrP和PVV则呈进行性下降,与其基础值相比差异显著(＜0.01),并且也低于相同MAC的D组相应各值(＜0.01).结论地氟醚对小儿LES功能无明显影响而安氟醚对其影响较大,故有高度反流危险的小儿,以选用地氟醚维持麻醉更为安全.     

The mechanism of acid-induced increases in canine lower esophageal sphincter pressure

Acidification of the gastric cardia has been shown to increase lower esophageal sphincter pressure (LESP). The mechanism by which this phenomenon occurs remains unknown. This study was undertaken to examine the effect and mechanism of action of proximal gastric acidification on LESP in the dog model. In long-term studies, acidification resulted in a significant increase in mean LESP (23.2 cm H2O). Pretreatment with either topical lidocaine or subcutaneous atropine blocked the sphincteric response to acidification. Neither truncal vagotomy and pyloroplasty, proximal gastric vagotomy, antral vagotomy and pyloroplasty, nor circumferential gastric myotomy significantly altered the sphincteric response to acid. Pretreatment with 6-hydroxydopamine or somatostatin also failed to alter the increase in LESP in response to acid. In short-term studies, after gastric transection 5 cm distal to the gastroesophageal junction, acidification of a vagally innervated distal gastric pouch produced a slight decrease in LESP, whereas acidification of the proximal (orad) section of gastric mucosa still resulted in a significant increase in LESP. These studies suggest that the increase in LESP observed with acidification of the gastric cardia is a local mechanism mediated by an intrinsic neural pathway dependent on cholinergic neurotransmission. This phenomenon of local reflex excitation may be another contributing mechanism to the barrier against gastroesophageal reflux.     

Preoperative lower esophageal sphincter pressure affects outcome of laparoscopic esophageal myotomy for achalasia

The primary aim of this study was to identify factors that influence outcome of the surgical treatment of achalasia. A secondary aim was to compare outcomes after laparoscopic Heller myotomy and partial fundoplication using either a Dor or Toupet hemifundoplication. Between 1994 and 2002, a total of 78 patients underwent laparoscopic Heller myotomy and partial fundoplication. Preoperative investigations included esophageal manometry, a videoesophogram, and upper gastrointestinal endoscopy with biopsy. In 64 patients (35 males and 29 females), telephone contact was possible at a median 24 months (IQR 14–34). A Dor fundoplication was performed in 41 patients and a Toupet fundoplication in 23. Symptoms were assessed prior to surgery and at follow-up by an independent physician using standardized definitions to grade the severity of dysphagia, regurgitation, and chest pain. To assess outcome, dysphagia was categorized as persistent or resolved. Persistent was defined as dysphagia that occurred on a weekly or daily basis. Resolved was defined as dysphagia that occurred occasionally or not at all. At follow-up, patients were asked to make a personal evaluation of their outcome as to whether (1) their swallowing was improved by the procedure, (2) they were satisfied with the outcome, and (3) they would undergo surgery again under the same circumstances. There was a significant improvement in dysphagia and regurgitation scores after surgery (P<0.05). The scores for chest pain/heartburn remained unchanged. By physician assessment, dysphagia was resolved in 49 patients (77%) and persisted in 15 (33%). By patient assessment, 62 patients (97%) reported an improvement in the symptom of dysphagia, and 60 (94%) stated that they were satisfied with their improvement and would undergo surgery if they had to make the choice again. On univariate analysis, patients who had resolution of their dysphagia had a significantly higher resting lower esophageal sphincter (LES) pressure prior to myotomy (P=0.01) and on multivariate analysis only a high resting LES pressure prior to surgery was a predictor of resolution of dysphagia (P=0.015). Outcome comparison of patients with Dor and Toupet fundoplications showed no significant differences in physician assessment of postoperative symptom scores and resolution of dysphagia, patient assessment of outcome, or postoperative use of proton pump inhibitors. Ninety-four percent of patients are satisfied with their surgical myotomy for achalasia. By physician assessment dysphagia was resolved in 77% of patients. Ahigh LES resting pressure before surgery predicted resolution of dysphagia.     

The effect of cyclizine hydrochloride on lower oesophageal sphincter pressure in man.

Gastro-oesophageal reflux and pulmonary aspiration of acid gastric content remain significant causes of morbidity and mortality. A drug which increases lower oesophageal sphincter (LOS) tone would reduce this hazard. The effect of LOS function of intravenous cyclizine (25 mg), in half the recommended adult dose, was investigated in 8 volunteers. Cyclizine increased the LOS pressure by an average of 14,4 cm H2O (P less than 0,005). Cyclizine, like metoclopramide, has a desirable functional effect on the LOS. Both drugs are, in addition, potent anti-emetics. On the grounds of these pharmacological properties they are recommended in the preparation of patients for emergency surgery.     

Celecoxib (celebrex) increases canine lower esophageal sphincter pressure

BACKGROUND: Prostaglandins inhibit the contraction of gastrointestinal smooth muscle and may decrease lower esophageal sphincter tone. The purpose of this study was to determine whether the cyclooxygenase-2 inhibitor celecoxib (Celebrex) could increase lower esophageal pressure (without affecting gastric emptying) compared to placebo and cisapride (Prepulsid), a compound previously used to treat reflux disease. MATERIALS AND METHODS: Six mongrel dogs were assigned to receive celecoxib, cisapride, and placebo using a randomized cross-over design with a 1-week washout period between treatments. Prior to dosing, each dog underwent an esophagopexy to provide access to the esophagus and stomach. On the fourth day of dosing, sphincter tone was measured in awake unsedated dogs using radial manometry. In a different set of six dogs, liquid and solid gastric emptying rates were scintigraphically determined. RESULTS: Celecoxib significantly increased mean and average maximum lower esophageal pressures compared to placebo without affecting the gastric emptying rate. The magnitudes of these increases were similar to that produced by cisapride. CONCLUSIONS: Celecoxib had a positive effect on canine lower esophageal sphincter tone. This finding, combined with the drug's low incidence of gastrointestinal toxicity, suggests that celecoxib may warrant consideration and investigation as a pharmacotherapy for human reflux disease.     

Interaction of lower esophageal sphincter pressure and length of sphincter in the abdomen as determinants of gastroesophageal competence

This study defines the components of distal esophageal sphincter function which predict gastroesophageal competence and examines the mechanisms by which three antireflux procedures restore competence to the cardia. In a prospective study, the reflux status of 391 patients was determined by 24 hour pH monitoring. Distal esophageal sphincter pressure and length of sphincter exposed to the positive pressure environment of the abdomen was measured by esophageal infusion manometry. Similar pre- and postoperative studies were performed in 45 patients who were randomized to three equal groups for the Hill, Belsey and Nissen antireflux procedures.Two hundred sixty-seven (68 percent) of the 391 patients had a positive 24 hour pH test. Competence of the cardia was related to pressure in the distal esophageal sphincter, to the length of sphincter in the abdomen and to an interaction between both (all p < 0.05). Thus, competence of the cardia requires an adequate pressure and length of sphincter in the abdomen. In determining competence, the pressure and length effects are not additive, but have an interacting relationship.Sphincter pressure and abdominal length are independently corrected by surgery. Restoration of competence requires increases in both. The gastric fundic wrap best augments distal esophageal sphincter pressure by application of normal functioning smooth muscle to the lower esophagus. Sphincter dynamics are normal after a wrap as the gastric fundus and distal esophageal sphincter share the functions of synchronous contraction and simultaneous relaxation on deglutition.