Intraoperative study on the relationship between the lower esophageal sphincter pressure and the muscular components of the gastro-esophageal junction in achalasic patients.

OBJECTIVE. The lower esophageal sphincter (LES) resting tone originates from the tension of the muscular fibers of the gastro-esophageal (GE) junction. This study determined which of the muscular structures' of the GE junction are actually responsible and to what degree for the LES resting tone in achalasic patients. SUMMARY BACKGROUND DATA. Controversy still exists as to the length of myotomy on the esophageal and gastric sides of the GE junction. Experimental and clinical studies have supposed that the anatomical complex formed by the U and the sling fibers of the lesser curvature of the stomach can be part of the LES. METHODS. The variations induced on the LES resting tone by the separate division of the esophageal and gastric muscular fibers of the GE junction were studied by means of intraoperative manometry in 32 patients who underwent myotomy for achalasia. RESULTS. After surgical preparation of the GE junction, the mean pressure was 29.3 +/- 13 mmHg. After esophageal side myotomy, the mean LES pressure decreased to 13.6 +/- 7.9 mmHg (paired t test, p < 0.0005). The residual pressure was further reduced after gastric side myotomy (3.4 +/- 1.9 mmHg; paired t test, p < 0.0005). CONCLUSIONS. In achalasic patients, 45% of the LES resting tone is maintained by the gastric side anatomical component of the GE junction. The range of variability of the gastric component of the LES is wide. This information should be taken into account when performing extramucosal myotomy as therapy for esophageal achalasia.     

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.     

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)     

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.     

Assessment of lower extremity venous function using foot venous pressure measurement.

BACKGROUND: Measurement of foot venous pressure (FVP) is useful for evaluating chronic venous insufficiency (CVI) functionally, because CVI always causes venous hypertension. In the present study, the various FVP parameters were analysed according to the new classification of venous disorders based on clinical, aetiological, anatomical and pathophysiological data (the CEAP classification). METHODS: During the past 7 years, a total of 257 legs in 196 consecutive patients with CVI have been studied. The following FVP parameters were assessed: the percentage decrease in pressure from rest with manual calf compression, the rate of increase of pressure during 4 s after compression (4SR) and the time to 50 per cent recovery of pressure (RT50) after release of compression. RESULTS: The incidence of skin changes due to venous stasis increased as the percentage pressure drop and RT50 fell. In addition, a pressure drop of less than 72 per cent and an RT50 of less than 20 s could detect legs with skin changes with a sensitivity of 76 per cent and a specificity of 62 per cent. In legs with primary varicose veins, pressure drop, 4SR and RT50 values deteriorated in proportion to the severity of the associated deep venous reflux. CONCLUSION: FVP parameters correlate well with the severity of clinical manifestations and venous reflux, and could be used quantitatively to evaluate the severity of CVI.     

Improvement in lower esophageal sphincter pressure following surgery for complicated gastroesophageal reflux.

A comparison was made of the pre- and postoperative lower esophageal sphincter (LES) pressures in nine patients undergoing a posterior gastropexy for complicated gastroesophageal reflux. LES pressure was increased from 4.4 plus or minus 0.4 mm Hg to 13.9 plus or minus 0.5 mm Hg following surgery (p less than .01). The ratio of the change in LES pressure compared to the change in gastric pressure during increases in intra-abdominal pressure delta S/delta G, was 0.59 plus or minus 0.05 preoperatively and 0.94 plus or minus .01 postoperatively (p less than .01). All patients were asymptomatic after surgery. Both the resting LES pressure and the S/G ratio following surgery were significantly less than the comparable values obtained in an age-matched control population (p less than .01). These studies suggest that the clinical improvement following surgery for gastroesophageal reflux may be due to the increase in resting LES pressure and the improved response of the LES to increased intra-abdominal pressure.     

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.     

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.     

Intraoperative measurement of pharynx/esophagus retraction during anterior cervical surgery. Part I: pressure

Temporary dysphagia after anterior cervical discectomy (ACD) is common. However, its mechanism is poorly understood. Pressure induced by retractor blades onto pharynx/esophagus were measured intraoperatively in order to gain more information regarding traumatization of the pharynx/esophagus wall. Thirty-one patients underwent anterior cervical discectomy and fusion (ACDF) for degenerative disc disease. An online pressure transducer was applied to the rear side of the medial retractor blade (epi-esophageal-pressure, epi-P) and a cylindric, inflatable transducer was preoperatively inserted into the pharynx/esophagus under fluoroscopic guidance at the level to be operated on (endo-esophageal-pressure, endo-P). Pressure values were recorded continuously during the operation. Mean arterial pressure (MAP) and endotracheal cuff pressure (ETCP) were recorded additionally. An in vitro model was developed in order to analyze the impact of the retractor blade design onto the epi-esophageal-pressure. Mean epi-P before and following adequate retractor opening for exposure of the disc space was 58.3 and 92.7 mmHg. Thirty, 60 and 90 min later the epi-P decreased to 79, 70 and 66%, respectively. Mean basal endo-P was 9.8 mmHg and increased to 20.6 mmHg after retractor placement. Thirty, 60 and 90 min later the endo-P decreased to 80, 71 and 62%, respectively. The mean MAP was 76 mmHg and the ECTP was adjusted to 25 mmHg during the procedures. In the in vitro model retraction pressure correlated inversely with the contact area between visceral wall and retractor blade. During ACDF the retraction pressure onto the pharyngeal/esophageal wall exceeds MAP and even more the mucosal perfusion pressure of 25 mmHg. Over time the pharynx/esophageal wall adapts to the applied pressure induced by the retractor blade. The contact area between them influences the retraction pressure.Part II of this article can be found under http://dx.doi.org/10.1007/s00586-006-0070-7     

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.     

Intraoperative measurement of shoulder translation

Assessing laxity of the shoulder joint in patients who are under anesthesia is a standard procedure before arthroscopy. The aim of this study was to evaluate a novel instrument for quick and reliable intraoperative measurement of glenohumeral translation. Previous testing of various designs has resulted in a device secured by 1 pin in the acromion and 1 pin in the proximal humerus. These pins are interconnected by a sliding ruler that gives translation values in millimeter increments as the laxity tests are performed. Comparison between manual arbitrary approximation of laxity and instrumented translation measurements showed that manual testing is reasonably good for assessment of anterior and posterior translation, without, however, providing values of translation in millimeter increments. The low correlation between manual assessment and instrumented inferior translation measurements indicates that inferior translation is more difficult to approximate manually. The shoulder translation tester was used in 102 patients. The mean values for clinically stable shoulders (n = 58) were 5 mm for anterior translation, 5 mm for posterior translation, and 4 mm for inferior translation. The corresponding values in unstable shoulders were significantly higher than in the stable shoulders, especially in patients with multidirectional instability. We conclude that the shoulder translation tester is easy and quick to use. It provides quantitative values of translation and will thus contribute information for correct diagnosis, therapy, and documentation.     

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