Letters To The Editor: Letters & Announcements
I have read with interest the review article by Ng and Smith (1). I would like to make the following points.
- 1. In Table 2, ranitidine is shown to have no effect on lower esophageal sphincter (LES) pressure. No reference is given to this statement. One study has shown no effect (2). Other studies have shown ranitidine to increase the LES tone (3,4). Furthermore, if ranitidine is given before atropine, there is no significant decrease in LES. This is also true for metoclopramide in both nonpregnant and pregnant subjects (5). This is important information for those clinical anesthesiologists who like to use atropine before general anesthesia, especially in the pregnant subject (5).
- 2. Protective airway reflexes have been shown to be decreased by many drugs including ketamine, neurolept analgesia with diazepam, and nitrous oxide in oxygen (6–8).
- 3. The author’s recommendation that a nasogastric tube should be left in situ during a rapid sequence technique induction is not supported by the evidence given by the authors. In a study by Manning et al. (9), episodes of reflux were significantly higher in patients with a nasogastric tube. Added to this was the fact that the LES pressure was lower in patients with a nasogastric tube compared with those without. Clinicians who have seen aspiration of gastric contents with a nasogastric tube in situ will, no doubt, remove the nasogastric tube before anesthesia induction to hopefully prevent aspiration.
- 4. It is well known that the LES tone showed adductive changes with increased abdominal compression. This is akin to the pregnant patient (10).
John G. Brock-Utne, MD, PhD
1. Ng A, Smith G. Gastroesophageal reflux and aspiration of gastric contents in anesthesia practice. Anesth Analg 2001; 93: 494–513.
2. Denis P, Galiniche JP, Ducrotte P, et al. Effect of ranitidine on resting gastric pressure and pentagastrin response of human lower esophageal sphincter. Dig Dis Sci 1981; 26: 999–1002.
3. Bertaccini C, Molina E, Bobbio P, Fogg E. Ranitidine increases lower oesophageal sphincter pressure in man. It J Gastroenterology 1981; 13: 149–50.
4. Brock-Utne JG, Downing JW, Humphrey D. Effect of ranitidine given before atropine sulphate on lower oesophageal sphincter tone. Anaesth Intensive Care 1984; 12: 140–2.
5. Brock-Utne JG, Dow TGB, Welman GE, et al. The effect of metoclopramide on the lower oesophageal sphincter in late pregnancy. Anaesth Intensive Care 1978; 6: 26.
6. Taylor PA, Towey RM. Depression of laryngeal reflexes during ketamine anaesthesia. BMJ 1971; 2: 688.
7. Brock-Utne JG, Winning TJ, Kingston HG Jr. Laryngeal incompetence during neuroleptanalgesia in combination with diazepam. Br J Anaesth 1976; 48: 699–701.
8. Rubin J, Brock-Utne JG, Greenberg M, et al. Laryngeal incompetence during experimental “relative analgesia” using 50% nitrous oxide in oxygen. Br J Anaesth 1977; 49: 1005.
9. Manning B, McGreal G, Winter DC, et al. Nasogastric intubation causes gastrooesophageal reflux in patients undergoing elective laparatomy. Br J Surg 2000; 87: 637.
10. Dow TGB, Mrcog JG, Brock-Utne JG, et al. The effect of atropine on the lower esophageal sphincter in late pregnancy. Obstet Gynecol 1978; 51: 426–30.