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Biomedical subjects

S S Kadirkamanathan

Publications and source records attributed to S S Kadirkamanathan.

11 recordsLinked to original sources
PubMed2001

Compliance measurement of lower esophageal sphincter and esophageal body in achalasia and gastroesophageal reflux disease.

Little is known about the effect of achalasia and gastroesophageal reflux disease (GERD) on compliance of the esophageal body and the lower esophageal sphincter (LES). Twenty-two patients with achalasia, 14 with GERD, and 14 asymptomatic volunteers were assessed. Recording apparatus consisted of a specially developed PVC bag tied to a compliance catheter, a barostat, and a polygraph. Intrabag pressures were increased incrementally while the bag volume was recorded. In each subject, pressure-volume graphs were constructed for both the esophageal body and LES and the compliance calculated. In achalasia, compliance of the esophageal body was significantly higher (P < 0.01) than in controls, whereas LES compliance was similar. Patients with GERD had a highly compliant LES in comparison to both controls and to patients with achalasia (P < 0.01 and P < 0.001, respectively); however there was no difference in their esophageal body compliance. In conclusion, foregut motility disorders can cause changes in organ compliance that are detectable using a barostat and a suitably designed compliance bag. Further measurement of compliance may provide clues to the pathogenesis of these disorders.

Adult↗
PubMed2001

Electrical stimulation for propelling endoscopes.

BACKGROUND: Methods are needed for propulsion of endoscopes and wireless video capsules along the small intestine. This work aims to test the hypothesis that electrical stimulation could propel an endoscope by stimulating muscular contraction. METHODS: Prototype acrylic ovoid-shaped devices were constructed with 2 stainless steel electrodes mounted on the tapered section. Five devices 15 to 23 mm diameter with a taper of 28 degrees to 40 degrees (included angle) were tested. When these devices were in contact with the bowel wall, electrostimulation was applied causing circular muscle contraction, which when applied to the taper of the ovoid resulted in forward propulsion of the device. The method does not induce peristalsis but works by stimulating local contraction. The device was tested in the small intestine and esophagus of anesthetized pigs. RESULTS: Electrostimulation caused the ovoid to advance rapidly (6 mm/sec) up and down the esophagus by inducing circular esophageal muscle contraction. When stimulated at 15 Hz with 30-ms pulses, the threshold for movement in the small intestine was 12 mA; at 20 mA the device moved reliably in either direction in the small intestine at speeds of up to 4.5 mm/sec and negotiated tight curves. CONCLUSION: Electrostimulation can move endoscopes in the small intestine.

Animals↗
PubMed1999

An ambulant porcine model of acid reflux used to evaluate endoscopic gastroplasty.

BACKGROUND: There is a lack of suitable models for testing of therapeutic procedures for gastro-oesophageal reflux disease. Endoscopic sewing methods might allow the development of a new less invasive surgical approach to treatment of gastrointestinal disorders. AIMS: To develop an animal model of gastro-oesophageal reflux for testing the efficacy of a new antireflux procedure, endoscopic gastroplasty, performed at flexible endoscopy without laparotomy or laparoscopy. METHODS: At endoscopy a pH sensitive radiotelemetry capsule was sewn to the oesophageal wall, 5 cm above the lower oesophageal sphincter, in six large white pigs. Ambulant pH recordings (48-96 hours; total 447 hours) were obtained. The median distal oesophageal pH was 6.8 (range 6.4-7.3); pH was less than 4 for 9.3% of the time. After one week, endoscopic gastroplasty was performed by placing sutures below the gastro-oesophageal junction, forming a neo-oesophagus of 1-2 cm in length. Postoperative manometry and pH recordings (24-96 hours; total 344 hours) were carried out. RESULTS: Following gastroplasty, the median sphincter pressure increased significantly from 3 to 6 mm Hg and in length from 3 to 3.75 cm. The median time pH was less than 4 decreased significantly from 9.3% to 0.2%. CONCLUSIONS: These are the first long term measurements of oesophageal pH in ambulant pigs. The finding of spontaneous reflux suggested a model for studying treatments of reflux. Endoscopic gastroplasty increased sphincter pressure and length and decreased acid reflux.

Animals↗
PubMed1998

A randomised controlled comparison of injection, thermal, and mechanical endoscopic methods of haemostasis on mesenteric vessels.

BACKGROUND AND AIMS: A randomised controlled comparison of haemostatic efficacy of mechanical, injection, and thermal methods of haemostasis was undertaken using canine mesenteric vessels to test the hypothesis that mechanical methods of haemostasis are more effective in controlling haemorrhage than injection or thermal methods. The diameter of arteries in human bleeding ulcers measures up to 3.45 mm; mesenteric vessels up to 5 mm were therefore studied. METHODS: Mesenteric vessels were randomised to treatment with injection sclerotherapy (adrenaline and ethanolamine), bipolar diathermy, or mechanical methods (band, clips, sewing machine, endoloops). The vessels were severed and haemostasis recorded. RESULTS: Injection sclerotherapy and clips failed to stop bleeding from vessels of 1 mm (n = 20) and 2 mm (n = 20). Bipolar diathermy was effective on 8/10 vessels of 2 mm but failed on 3 mm vessels (n = 5). Unstretched elastic bands succeeded on 13/15 vessels of 2 mm but on only 3/10 vessels of 3 mm. The sewing machine achieved haemostasis on 8/10 vessels of 4 mm but failed on 5 mm vessels (n = 5); endoloops were effective on all 5 mm vessels (n = 5). CONCLUSIONS: Only mechanical methods were effective on vessels greater than 2 mm in diameter. Some mechanical methods (banding and clips) were less effective than expected and need modification. Thermal and (effective) mechanical methods were significantly (p < 0.01) more effective than injection sclerotherapy. The most effective mechanical methods were significantly more effective (p < 0.01) than thermal or injection on vessels greater than 2 mm.

Animals↗
PubMed1996

Antireflux operations at flexible endoscopy using endoluminal stitching techniques: an experimental study.

BACKGROUND: Three antireflux operations-gastroplasty, fundoplication, and anterior gastropexy-were developed for performance at flexible endoscopy without laparotomy or laparoscopy. METHODS: An endoscopic sewing machine mounted on a standard gastroscope, endoscopic knotting devices, overtube, and nylon thread were used to perform these operations in adult beagle dogs. RESULTS: Gastroplasty (n = 10) was accomplished by suturing the anterior and posterior wall of the stomach to create a gastric tube (neoesophagus) along the lesser curve. An anatomic arrangement similar to fundoplication (n = 6) was achieved by invaginating the esophagus and fixing it to the stomach 2 cm distal to the cardioesophageal junction. Anterior gastropexy (n = 6) was performed using a technique similar to that used in creating percutaneous gastrostomies. There was no mortality. Ninety percent of sutures were seen at repeat endoscopy at 4 to 8 week intervals. The gastroplasty group was selected for more extensive evaluation. Manometry using a three-channel perfused catheter system before and after the procedures showed an increase in the lower esophageal sphincter pressure (preoperative median 4.6 mm Hg; post-operative median 13.33 mm Hg, p = 0.008) and cardiac yield pressures (preoperative median 10 mm Hg; postoperative median 19 mm Hg, p = 0.007). CONCLUSIONS: This study demonstrates the feasibility of performing antireflux operations at flexible endoscopy, without laparoscopy or laparotomy, by use of endoluminal suturing techniques.

Animals↗
PubMed1996

A comparison of the strength of knots tied by hand and at laparoscopy.

BACKGROUND: The strength of knots tied at laparoscopy was compared with that of hand-tied knots. STUDY DESIGN: The force needed to undo or break eight types of knots that were tied in fresh postmortem human stomachs was measured. The knotting performance of nylon, polyglactin 910, braided silk, polytetrafluoroethylene, braided polyester fiber, braided polyester suture, polyamide 66, and polydiaxone was also compared. RESULTS: Measurements of knot strength of two to six half hitches (hand tied) showed that four half hitches were necessary to tie a secure nonslipping knot with most monofilament threads (nylon, polytetrafluoroethylene, braided polyester suture, and polyamide 66), while three half hitches were adequate to secure a knot when polyglactin 910, braided polyester fiber, silk, and polydiaxone were used. Additional throws did not increase knot strength once the knot no longer slipped (p = NS). Some commonly tied knots, three half hitches and surgical knots at laparoscopy were weaker than the same hand-tied knots (p < 0.05) but an additional throw increased knot security (p < 0.01). Differences between laparoscopic and hand-tied knot strengths were greater for monofilament than multifilament threads. There was a wider distribution of strengths for laparoscopically tied than hand-tied knots. Four half hitches were the most secure configuration for laparoscopically tied knots and were significantly stronger than three half hitches and surgical knots (p < 0.01). The extracorporeally tied slipknot (Roeder loop) was significantly less secure than four half hitches (p < 0.05). CONCLUSIONS: This study demonstrates that laparoscopically formed knots may be weaker than those tied by hand and shows that improvements in knot strength at laparoscopy can be achieved by choice of optimal knot configuration for different suture materials.

Evaluation Studies as Topic↗
PubMed1995

Physiological and symptomatic outcome after laparoscopic gastric fundoplication.

The complications of open antireflux operations may be reduced by laparoscopic techniques. Fifteen patients of median age 42 (range 16-79) years with gastro-oesophageal reflux underwent laparoscopic fundoplication. Preoperative and postoperative assessment was by clinical scoring, oesophageal pH measurement and manometry. Median (range) operating time was 115 (60-210) min and hospital stay 3 (1-6) days, with no conversions to open operation and only one minor wound infection. Four patients had occasional reflux symptoms on postoperative assessment at a median of 7 weeks and nine had occasional dysphagia. Median DeMeester symptom scores improved from 4 to 1.5 (P = 0.001). There were significant increases in both lower oesophageal sphincter pressure and length. The nocturnal proportion of time at pH < 4 decreased from 9.6 to 0.05 per cent (P = 0.02), although the drop in total proportion of time at pH < 4 (10.4 to 2.2 per cent) was not statistically significant (P = 0.08). Early objective results of laparoscopic fundoplication show improved symptoms, decreased acid reflux and altered lower sphincter function. The procedure combines the benefits of early mobilization and reduced morbidity with the efficacy of the traditional open operation.

Adolescent↗
PubMedDate not supplied

Knot tying at flexible endoscopy.

Four new knotting techniques were developed for use at flexible endoscopy: (1) half hitches tied with knot-pusher, (2) thread-locking device, (3) self-tightening slip-knot, and (4) externally releasable knot. Remoteness from site of action, access through small-diameter orifice, and difficulty in applying lateral traction to tighten knots are problems met in knot tying at endoscopy. All four knotting techniques were studied in experiments on postmortem human stomachs and used for radio-telemetry studies and anti-reflux operations in survival studies in dogs using endoscopic sewing techniques. Half hitches tied at endoscopy with a knot-pusher were also used in human studies to treat esophageal reflux and secure pH radio-telemetry capsules for long-term measurements. Externally releasable knots were used to secure nasogastric tubes to the stomach of five patients for long-term nutrition. Knot tying is feasible at flexible endoscopy by a variety of new techniques. Endoscopically tied knots can be as secure as surgically hand-tied knots and have been used successfully in man.

Animals↗