Esophageal sphincter

XANTHINE DERIVATIVES. The patient taking theophylline may report heartburn because the drug relaxes the lower esophageal sphincter, allowing gastroesophageal reflux. Heartburn is minimized if the patient remains in an upright position and sleeps with the head of die bed elevated. 

The lower esophageal sphincter is a manometrically-defined zone of the distal esophagus with an elevated basal resting pressure. The sphincter is normally in a tonic, contracted state, preventing the reflux of gastric material from the stomach. It relaxes on swallowing to permit the free passage of food into the stomach. 

Second, reflux may occur after transient increases in intraabdominal pressure (stress reflux).3 An increase in intraabdominal pressure such as that occurring during straining, bending over, coughing, eating, or a Valsalva maneuver may overcome a weak lower esophageal sphincter, and thus may lead to reflux. 

Third, the lower esophageal sphincter may be atonic, thus permitting free reflux. Although transient relaxations are more likely to occur when there is normal lower esophageal sphincter pressure, the latter two mechanisms are more likely... 

The pathophysiology of GERD is a complex process. It is difficult to determine which occurs first gastroesophageal reflux leading to defective peristalsis with delayed clearing, or an incompetent lower esophageal sphincter pressure leading... 

Surgical intervention is a viable alternative for selected patients with well-documented GERD.1 The goal of surgery is to re-establish the anti-reflux barrier, to position the lower esophageal sphincter within the abdomen where it is under positive (intra-abdominal) pressure, and to close any associated hiatal defect.11 It should be considered in patients who (1) fail to respond to pharmacologic treatment (2) opt for... 

Gastroesophageal reflux occurs in approximately 18% of infants. As in adults, transient lower esophageal sphincter relaxations appear to be the most common cause of GERD.26 This is due to developmental immaturity of the lower esophageal sphincter.27 Other causes include impaired luminal clearance of gastric acid, neurologic impairment, and type of infant formula. 

GERD gastroesophageal reflux disease H2RA histamine2-receptor antagonist LES lower esophageal sphincter... 

Peppermint oil is widely advocated it acts as an antispas-modic agent due to its ability to relax gastrointestinal smooth muscle. However, it also relaxes the lower esophageal sphincter, which could allow reflux of gastric contents into the esophagus. The usual dose is 1 to 2 enteric-coated capsules containing 0.2 mL of peppermint oil two to three times daily. 

Gastroparesis/atony causing regurgitation Feeding tube malpositioned Compromised lower esophageal sphincter Diminished gag reflex... 

LES Lower esophageal sphincter NIH National Institutes of Health... 

In some cases, gastroesophageal reflux is associated with defective lower esophageal sphincter (LES) pressure or function. Patients may have decreased LES pressures related to spontaneous transient LES relaxations, transient increases in intraabdominal pressure, or an atonic LES. A variety of foods and medications may decrease LES pressure (Table 24-1). 

Decreased lower esophageal sphincter pressure Foods ... 

Avoid foods that may decrease lower esophageal sphincter pressure (fats, chocolate, alcohol, peppermint, and spearmint). 

Include protein-rich meals in diet (augments lower esophageal sphincter pressure). 

Stop smoking (decreases spontaneous esophageal sphincter relaxation). 

Avoid alcohol (increases amplitude of the lower esophageal sphincter, peristaltic waves, and frequency of contraction). 

Metoclopramide increases lower esophageal sphincter tone, aids gastric emptying, and accelerates transit through the small bowel, possibly through the release of acetylcholine. 

Botulinum toxin from Clostridium botulinum is the most potent poison known. The lethal dose in an adult is approx. 3x10 mg. The toxin blocks exo-cytosis of ACh in motor (and also parasympathetic) nerve endings. Death is caused by paralysis of respiratory muscles. Injected intramuscularly at minuscule dosage, botulinum toxin type A is used to treat blepharospasm, strabismus, achalasia of the lower esophageal sphincter, and spastic aphonia. 

Pharmacology The methyixanthines (theophylline, its soluble salts and derivatives) directly relax the smooth muscle of the bronchi and pulmonary blood vessels, stimulate the CNS, induce diuresis, increase gastric acid secretion, reduce lower esophageal sphincter pressure, and inhibit uterine contractions. Theophylline is also a central respiratory stimulant. Aminophylline has a potent effect on diaphragmatic contractility in healthy people and may then be capable of reducing fatigability and thereby improve contractility in patients with chronic obstructive airways disease. Pharmacokinetics ... 

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