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Biomedical subjects

M R Cox

Publications and source records attributed to M R Cox.

49 records · Page 3Linked to original sources
PubMed1990

Response of canine lower esophageal sphincter to gastric distension.

The aim of this study was to localize the region of the stomach responsible for triggering distension-induced transient lower esophageal sphincter relaxation (TLESR). The canine stomach was partitioned into subsegments by a row of buttressed sutures. This separated either the fundus from the lesser curve or the proximal stomach from the antrum. After 1 mo each region was progressively distended while gastroesophageal pressures were monitored. At the time of the first TLESR, gastric wall tension was estimated from the bag pressure and volume. Distension of the intact stomach, lesser curve, or proximal stomach in 12 dogs produced a progressive increase in lower esophageal sphincter (LES) pressure, which was interrupted at low gastric wall tension (29, 35, and 40 mmHg.cm, respectively) by a superimposed TLESR. Background LES pressure fell progressively with distension of the antrum but was unchanged by distension of the fundus alone. Both the fundus and antrum had significantly higher thresholds for triggering TLESR (96 and 105 mmHg.cm). In another two dogs truncal vagotomy performed at the time of gastric partitioning prevented both the change in background LES pressure, and the triggering of TLESR, associated with proximal gastric and antral distension. We conclude that the subcardiac region of the stomach is primarily responsible for triggering TLESR induced by distension and that the effect on background LES pressure depends on the region distended.

Animals↗
PubMed1988

Effect of general anaesthesia on transient lower oesophageal sphincter relaxations in the dog.

This report investigates the hypothesis that gastro-oesophageal flow is modulated by central nervous activity. The hypothesis was examined using the canine model in which gastro-oesophageal flow was stimulated by gastric insufflation of air at 80 ml/min and central nervous depression was produced with the anaesthetic agents thiopentone, nitrous oxide and halothane. Duplicate paired studies were performed in four dogs, either unsedated or anaesthetized. Gastro-oesophageal flow was assessed manometrically by a sleeve catheter assembly and by pH electrode. Gastric compliance was assessed by inflation of a thin-walled, plastic bag. Transient lower oesophageal sphincter relaxation, the dominant mechanism of retrograde trans-sphincter flow in unsedated animals, was abolished by general anaesthesia. Retrograde flow of gas across the lower oesophageal sphincter in anaesthetized animals eventually occurred, but only after massive gastric distension and elevation of gastric pressure to lower oesophageal sphincter pressure. The effects observed could not be explained by a direct action of anaesthetic on the lower oesophageal sphincter or on the gastric wall. It is proposed that general anaesthesia results in blockade of the neural pathway responsible for transient lower oesophageal sphincter relaxation by withdrawal of facilitative higher centre activity. The findings have implications for the use of sedation in experimental studies on factors which control gastro-oesophageal reflux, and clinical application to the risk of tracheal aspiration during general anaesthesia.

Anesthesia, General↗
PubMedDate not supplied

Minimizing the risk of bile duct injury at laparoscopic cholecystectomy.

The introduction of laparoscopic cholecystectomy (LC) has been associated with an increase in the incidence of operative bile duct injuries. An operative technique that involves commencing the laparoscopic dissection on the body of the gallbladder and dissecting toward the cystic duct has been developed that minimizes the risk of major duct injury. The aim of this study was to assess prospectively the safety of this dissection technique. A group of 410 patients underwent LC for symptomatic cholelithiasis from January 1991 to December 1992. There was a single common hepatic duct injury: a small (1 mm) side hole in a patient with acute cholecystitis and choledocholithiasis. It was managed at open operation with exploration of the common bile duct and insertion of a T-tube. There were no partial or complete common bile duct transections in this series. We concluded that the technique of commencing the dissection on the gallbladder is safe and minimizes the risk of serious common bile duct injury at LC.

Bile Ducts↗
PubMedDate not supplied

Percutaneous cystogastrostomy with a new catheter for drainage of pancreatic pseudocysts and fluid collections.

We describe a new catheter for the initial percutaneous drainage of large symptomatic pancreatic fluid collections and abscesses using a transgastric approach to allow fluid drainage into the gastric lumen. A double-mushroom stent is placed secondarily for long-term internal drainage to the stomach, avoiding the need for an extended period of external catheter drainage. This technique, termed percutaneous cystogastrostomy (PCG), has been used in 19 consecutive patients with one recurrent symptomatic pseudocyst in the follow-up period fo 9-43 months. There was one death within 30 days of PCG and 1 patient proceeded to surgical necrosectomy. After evidence of resolution of the pseudocysts, the internal stent was retrieved in 17 patients by endoscopic snare.

Abscess↗
PubMedDate not supplied

Prospective randomized comparison of open versus laparoscopic appendectomy in men.

A prospective, randomized trial was performed to compare open appendectomy with laparoscopic appendectomy in men with a clinical diagnosis of acute appendicitis. Sixty-four patients with a median age of 25 years (range 18-84 years) were randomized to open appendectomy (n = 31) or laparoscopic (n = 33) appendectomy. Of the 64 men, 56 (87.5%) had appendicitis (27 open, 29 laparoscopic procedures). The mean operating times were 50.6 +/- 3.7 minutes (+/- SEM) for open and 58.9 +/- 4.0 minutes for laparoscopic appendectomy (p = 0.13). Five (15%) patients randomized to laparoscopic appendectomy had an open operation. The mean postoperative hospital stay was significantly longer for open appendectomy (3.8 +/- 0.4 days) than for laparoscopic appendectomy (2.9 +/- 0.3 days) (t = 2. 05,df = 62,p = 0.045). The complication rate after open appendectomy (25.8%) was not significantly different from that after laparoscopic appendectomy (12.1%). There was a single postoperative death due to a pulmonary embolus in the laparoscopic group and a single death due to cardiac and renal failure in the open group. The mean time to return to normal activities was significantly longer following open appendectomy (19.7 +/- 2.4 days) than after laparoscopic appendectomy (10.4 +/- 0.9 days), (t = 3.75,df = 49,p = 0.001). In conclusion, laparoscopic appendectomy in men has significant advantages in terms of a more rapid recovery compared to open appendectomy. There were no significant disadvantages to laparoscopic appendectomy compared to open appendectomy.

Adolescent↗
PubMedDate not supplied

Influence of posture on transient lower oesophageal sphincter relaxation and gastro-oesophageal reflux in the dog.

The hypothesis that suppression of transient lower oesophageal sphincter relaxation (TLOSR) in recumbent postures in the dog is dependent upon the sensing of a gastric pool of liquid in proximity to the lower oesophageal sphincter was examined. Constant gastric insufflation with air (80 ml/min) was used to evoke TLOSR in unsedated, fasting animals. Oesophageal motility was monitored with a perfused manometric sleeve catheter assembly. Gastrooesophageal flow was recognized manometrically and by oesophageal pH recording. TLOSR occurred significantly less frequently in three recumbent positions (right lateral, left lateral and supine) than when the dog stood on four legs, but was more likely to be associated with acid reflux when they occurred in recumbent positions. Aspiration of the gastric pool was found to have no effect on triggering of TLOSR although it reduced the frequency with which acid reflux was associated with TLOSR. It is concluded that the low rate of occurrence of TLOSR in recumbent positions is unlikely to be explained by the presence of a gastric pool of liquid in proximity to the lower oesophageal sphincter.

Animals↗