Biomedical subjects

J Dent

Publications and source records attributed to J Dent.

At least 109 records · Page 6Linked to original sources

PubMed1997

Spatial patterns of fasting and fed antropyloric pressure waves in humans.

1. Gastric mechanics were investigated by categorizing the temporal and spatial patterning of pressure waves associated with individual gastric contractions. 2. In twelve healthy volunteers, intraluminal pressures were monitored from nine side hole recording points spaced at 1.5 cm intervals along the antrum, pylorus and duodenum. 3. Pressure wave sequences that occurred during phase II fasting contractions (n = 221) and after food (n = 778) were evaluated. 4. The most common pattern of pressure wave onset along the antrum was a variable combination of antegrade, synchronous and retrograde propagation between side hole pairs. This variable pattern accounted for 42% of sequences after food, and 34% during fasting (P < 0.05). Other common pressure wave sequence patterns were: purely antegrade-29% after food and 42% during fasting (P < 0.05); purely synchronous-23% fed and 17% fasting; and purely retrograde-6% fed and 8% fasting. The length of sequences was shorter after food (P < 0.05). Some sequences 'skipped' individual recording points. 5. The spatial patterning of gastric pressure wave sequences is diverse, and may explain the differing mechanical outcomes among individual gastric contractions. 6. Better understanding of gastric mechanics may be gained from temporally precise correlations of luminal flows and pressures and gastric wall motion during individual gastric contraction sequences.

Adult↗

PubMed1997

Lamivudine is effective in suppressing hepatitis B virus DNA in Chinese hepatitis B surface antigen carriers: a placebo-controlled trial.

Lamivudine is a novel 2',3'-dideoxy cytosine analogue that has potent inhibitory effects on hepatitis B virus replication in vitro and in vivo. We performed a single-blind, placebo-controlled study to assess its effectiveness and safety in Chinese hepatitis B surface antigen (HBsAg) carriers. Forty-two Chinese HBsAg carriers were randomized to receive placebo (6 patients) or lamivudine orally in dosages of 25 mg, 100 mg, or 300 mg daily (12 patients for each dosage). The drug was given for 4 weeks. The patients were closely monitored clinically, biochemically, and serologically up to 4 weeks after drug treatment. All 36 patients receiving lamivudine had a decrease in hepatitis B virus (HBV) DNA values of >90% (P < .001 compared with placebo). Although 25 mg of lamivudine was slightly less effective than 100 mg (P = .011) and 300 mg (P = .005), it still induced 94% suppression of HBV DNA after the fourth week of therapy. HBV DNA values returned to pretreatment levels within 4 weeks of cessation of therapy. There was no change in the hepatitis B e antigen status or in aminotransferase levels. No serious adverse events were observed. In conclusion, a 4-week course of lamivudine was safe and effective in suppression of HBV DNA in Chinese HBsAg carriers. The suppression was >90% but reversible. Studies with long-term lamivudine administration should be performed to determine if prolonged suppression of HBV DNA can be achieved.

Adolescent↗

PubMed1997

Hyperglycemia affects gastric electrical rhythm and nausea during intraduodenal triglyceride infusion.

Hyperglycemia slows gastric emptying and increases the intensity of perception of gastric distension during fasting and small intestinal nutrient stimulation. In order to examine the possibility that abnormalities of gastric electrical rhythm may be associated with the effects of hyperglycemia, the gastric electrical rhythm (cutaneous electrogastrogram) and the perception rating scores for upper gastrointestinal sensations (visual analog scale) were examined. Studies were performed during intraduodenal triglyceride infusion in 10 healthy volunteers under euglycemic and hyperglycemic (approximately 15 mmol/liter) conditions. During fasting, hyperglycemia had no effect on either gastric electrical rhythm or sensation. Intraduodenal triglyceride infusion was associated with an increase in bradygastria (<2.4 cpm) during both euglycemia (33 +/- 9%) and hyperglycemia (36 +/- 10%, P < 0.05 vs baseline for each). During intraduodenal triglyceride infusion, tachygastria (>3.6 cpm) was more prevalent during hyperglycemia when compared to euglycemia (25 +/- 10% vs 1 +/- 1%, P < 0.05) and the perception rating scores for nausea and abdominal discomfort were greater during hyperglycemia (P < 0.05 for both). The intensity of nausea correlated with the proportion of time spent in tachygastria (r = 0.64, P < 0.01). These data are consistent with the concept that postprandial upper gastrointestinal symptoms in patients with diabetes mellitus may be modulated by the blood glucose concentration.

Adult↗

PubMed1997

Prognostic factors influencing relapse of oesophagitis during maintenance therapy with antisecretory drugs: a meta-analysis of long-term omeprazole trials.

BACKGROUND: This meta-analysis investigated factors that may affect the risk of relapse of oesophagitis, and evaluated the predictive value of symptoms for the presence of relapse during long-term treatment. METHODS: Individual data from 1154 patients included in five independently conducted, randomized, long-term clinical trials of the efficacy of different dosage regimens of omeprazole, standard ranitidine treatment and placebo for the prevention of relapse of oesophagitis were pooled for this meta-analysis. The therapeutic regimens studied were omeprazole 20 mg o.m. (OME20) in 366 patients, omeprazole 10 mg o.m. (OME10) in 225 patients, omeprazole 20 mg weekends (OMEW) in 235 patients, ranitidine 150 mg b.d. (RAN) in 179 patients, or placebo (PLA) in 149 patients. RESULTS: OME20 maintained 82.4% (95% CI: 78.2-86.6%) of patients in endoscopic remission over the 6-month period compared to 71.9% (95% CI: 65.5-78.3%) for OME10, 52.3% (95% CI: 44.4-60.1%) for RAN, 42.7% (95% CI: 35.8-49.5%) for OMEW, and 10.6% (95% CI: 5.0-16.3%) for PLA. A Cox's regression analysis of time to recurrence of oesophagitis showed that four factors were associated with a higher relapse rate during placebo and active maintenance therapy: (a) pre-treatment severity of oesophagitis (P < 0.0001), (b) young age (P = 0.01), (c) non-smoking (P = 0.02) and (d) moderate/severe regurgitation before entry into the trials (P = 0.03). Asymptomatic relapse of oesophagitis was uncommon, being found in only 8.6% of the patients. CONCLUSIONS: Maintenance treatment with omeprazole 10 and 20 mg daily is superior to all other regimens tested, and is only marginally influenced by the pretreatment severity of oesophagitis. Age contributes to the factors that influence the outcome during long-term treatment with omeprazole. Symptom relief is highly predictive for the maintenance of healing.

Adolescent↗

PubMed1997

Responses of the rat lower oesophageal sphincter (LOS) to vagal efferent activation.

Nitric oxide (NO) is a major candidate in vagal-induced LOS relaxation. Vagal adrenergic fibres also innervate the gastrointestinal tract including the LOS. This study investigates the role of these two and other mechanisms in LOS responses to vagal activation in the rat, and provides functional and anatomical evidence for a smooth muscle LOS in this species. LOS, gastric and oesophageal pressures were measured in urethane anaesthetized rats during vagal stimulation. The LOS pressure (LOSP) response to Vagal stimulation (5 mA, 10 Hz, 0.5 msec pulses, 5 sec) comprised three consecutive stages: (1) brief reduction of LOSP, (2) transient increase of LOSP and (3) prolonged reduction of LOSP. The influences of additive treatment with several antagonist drugs on the LOS response to vagal stimulation were investigated. L-NAME (100 mg kg-1) reduced stage 1 and increased stage 2. Subsequent treatment with either phentolamine (1 mg kg-1) or prazosin (200 micrograms kg-1) abolished stage 1. After phentolamine, atropine treatment (400 micrograms kg-1) abolished stage 2. Stage 3 was evident throughout experiments. In five additional studies, treatment with hexamethonium (30 mg kg-1) abolished stages 2 and 3 leaving stage 1, which was later abolished by phentolamine or atropine. In the LOS response to vagal stimulation, the following major mechanisms are therefore evident: nicotinic transmission in both excitation and inhibition, alpha-adrenergic and NO-mediated inhibition, muscarinic excitation, and non-adrenergic, non-NO inhibition (not characterized further). Characteristics of these different neurotransmitter influences may be important in LOS relaxation associated with swallowing and gastro-oesophageal reflux.

Animals↗

PubMed1997

Pyloric motor response to central and peripheral nitric oxide in the ferret.

This study has investigated the relative importance of central nervous and peripheral nitroxidergic mechanisms in the control of pyloric motility. In 10 urethane-anaesthetized ferrets, drugs were administered directly to the CNS via a 0.5-mm-diameter cannula inserted into the 4th ventricle, approximately at the obex. Drugs were also given directly to the upper GI tract by close intra-arterial (i.a.) injection at the coeliac axis. Antropyloroduodenal pressures were recorded with a five-channel sleeve/sidehole micromanometric assembly (1.35 x 1.75 mm o.d.), which was introduced via the duodenum. Pyloric motility was stimulated throughout the main part of each study with a continuous i.v. infusion of CCK-8 (30 pmol min-1). This infusion produced an immediate and sustained increase in tonic and phasic pyloric activity, and sustained abolition of antral pressure waves. CCK-8 also induced a duodenal motor response, but this was short-lived (11.4 +/- 7.9 min). Coeliac axis injection of the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) decreased phasic pyloric activity (from 330 +/- 35 to 148 +/- 21 mmHg min-1 after SNAP 5 micrograms, P < 0.01). By comparison central SNAP administration over the same dose range had no effect on CCK-stimulated pyloric motlity. Inhibition of endogenous NO synthase with L-Nitro Arginine Methyl Ester (L-NAME, 100 mg kg-1 close i.a.) caused a marked increase of phase pyloric motor activity from 349 +/- 59 to 1044 +/- 140 mmHg min-1 (P < 0.01). In addition, SNAP caused marked stimulation of pyloric tone from 2.6 +/- 0.5 to 13.1 +/- 2.8 mmHg (P < 0.01). Central nervous administration of L-NAME caused modest enhancement of phasic pyloric activity (248 +/- 31 to 283 +/- 32 mmHg min-1 P < 0.05) and pyloric tone (2.6 +/- 0.5 to 3.7 +/- 0.7 mmHg, P < 0.05). Our data indicate that motor activity of the ferret pylorus is potently modulated by NO released within the upper gut. Additionally, there is potential for modulation of pyloric motility by central nervous system production of NO.

Animals↗

PubMed1997

Mechanisms responsible for gastroesophageal reflux in children.

BACKGROUND & AIMS: There is limited information about the motor mechanisms responsible for gastroesophageal reflux (GER) in children. The aim of this study was to evaluate the relationship between esophageal body and lower esophageal sphincter (LES) motor events and the occurrence of GER. METHODS: Concurrent esophageal manometry and pH monitoring was conducted for 4 hours postprandially in 37 children referred for evaluation of suspected pathological GER. Presence of esophagitis and/or abnormal esophageal acid exposure was used to classify patients into two groups: those with pathological GER (group A; n = 24) and those in whom GER was not confirmed (group B; n = 13). RESULTS: GER occurred during LES relaxations unassociated with swallowing within 5 seconds before and 2 seconds after the onset of LES relaxation in 58% (group A) and 69% (group B) of the analyzable episodes. These swallow-independent sphincter relaxations satisfied criteria for classification as transient LES relaxations. An additional 23% (group A) and 19% (group B) of reflux episodes could have been a result of transient LES relaxation associated with swallowing by chance. Persistent absence of LES tone was an infrequent association of reflux and was confined to group A patients (8% of episodes). CONCLUSIONS: Transient LES relaxation is the most important cause of GER in children. Absent basal LES pressure is a relatively infrequent cause of reflux and only in children with pathological GER.

Adolescent↗

PubMed1997

Characterisation of relaxation of the lower oesophageal sphincter in healthy premature infants.

BACKGROUND: Gastro-oesophageal reflux disease causes significant morbidity in premature infants, but the role of dysfunction of the lower oesophageal sphincter (LOS) in this condition is unclear. METHODS: Oesophageal manometry was performed after gavage feeding in 13 healthy preterm neonates (postmenstrual age > or = 33 weeks) with a perfused sleeve with side hole assembly. Swallow related (both single and multiple) and transient LOS relaxations (TLOSRs) were identified and the characteristics of these events defined. Reflux was identified with manometric criteria (common cavity episodes). RESULTS: Five hundred and eleven relaxation of the LOS were observed, 55% related to single swallows, 23% related to multiple swallows, and 22% TLOSRs. The time to maximal LOS relaxation was longer for TLOSRs than for single or multiple swallows (mean (SEM) 5.0 (0.3) s v 3.0 (0.1) s and 3.3 (0.1) s, p < 0.0001 and p < 0.005). The durations of multiple swallows and TLOSRs were longer than single swallows (12.2 (0.5) s and 11.2 (0.4) s v 5.3 (0.2) s, p < 0.0001). Most of the oesophageal body common cavity episodes (94%) occurred during TLOSRs. CONCLUSIONS: In healthy preterm infants (postmenstrual age > or = 33 weeks) the motor events associated with LOS relaxation were similar to those seen in healthy adults. TLOSRs may be an important mechanism of reflux in premature infants.

Deglutition↗

PubMed1997

Effect of intraduodenal fat on lower oesophageal sphincter function and gastro-oesophageal reflux.

BACKGROUND AND AIMS: Fatty foods are commonly reported to aggravate gastro-oesophageal reflux symptoms. In this study the hypothesis that fat provokes reflux by stimulating transient lower oesophageal sphincter relaxations via small intestinal receptors was investigated. METHODS: In 12 healthy volunteers and 11 patients with reflux oesophagitis, oesophageal motility and pH were measured over 30 minute periods during which saline or fat (10% Intralipid) were infused in random order into the duodenum. The infusion periods were separated by a 30 minute washout. The stomach was loaded with 200 ml 10% dextrose, maintained by an intragastric infusion. RESULTS: Fat decreased basal LOS pressure from 16.9 (SEM 2.1) to 12.4 (SEM 1.5) mm Hg in normal subjects but had no effect in patients with oesophagitis (18.8 (SEM 4.3) v 18.2 (SEM 3.0) mm Hg). During saline infusion, the rates of transient lower oesophageal sphincter relaxation and reflux episodes were greater in patients (4.5 (interquartile range 2-11)/30 min and 5 (2-14)/30 min respectively) than in controls (3 (2-4)/30 min and 3 (2-3.5)/30 min respectively). Fat increased the rate of reflux episodes in the reflux patients to 6.5 (3-25)/30 min. This effect was due to an increase in the incidence of reflux during transient LOS relaxations (65% v 91%), the rate of transient relaxations remaining unchanged. CONCLUSIONS: Instillation of fat directly into the duodenum aggravates reflux in patients with reflux disease, by increasing the proportion of transient LOS relaxations accompanied by reflux.

Adolescent↗

PubMed1997

Effect of fundoplication on transient lower oesophageal sphincter relaxation and gas reflux.

BACKGROUND: Fundoplication is used widely to treat severe gastro-oesophageal reflux disease. Difficulty in belching and increased flatulence are common side-effects. Transient lower oesophageal sphincter (LOS) relaxation is important to help vent gas from the stomach. The effect of fundoplication on LOS function and gas reflux was therefore investigated. METHODS: Oesophageal manometry was performed before operation and 3-15 months after fundoplication in 14 patients with reflux disease who had a total (360 degrees) fundoplication. Five patients also had highly selective vagotomy. Gastric distension was induced by 750 ml carbon dioxide. RESULTS: Fundoplication reduced the median number of episodes of gas reflux during 10 min of gastric distension from 5 (interquartile range (i.q.r.) 3-7) to 0 (i.q.r. 0), and the median number of transient LOS relaxations from 4 (i.q.r. 2-6) to 0 (i.q.r. 0-1). Fundoplication did not affect basal LOS pressure but significantly increased nadir pressure during swallow-induced relaxation. CONCLUSION: Fundoplication controls reflux by inhibiting the triggering of transient LOS relaxation and by preventing the complete ablation of pressure at the gastro-oesophageal junction during LOS relaxation. These effects may also contribute to the side-effects of the operation.

Adult↗

PubMed1996

Preservation of normal gastric emptying following gastric surgery by use of a muscle bridge.

BACKGROUND: Maintenance of descending antral intramural pathways may be important in normal functioning of the pylorus after pylorus-preserving gastrectomy. METHODS: We examined the effect of a 1-cm bridge of muscle as a means of maintaining pyloric connection to antral intramural motor control pathways in 10 pigs. Antropyloroduodenal pressures and transpyloric flow were measured during gastric emptying of saline before and after either total or subtotal transection and reanastomosis of antrum. RESULTS: Complete antral transection shortened the time interval between antral and subsequent pyloric lumen occlusion, significantly reducing total gastric emptying and volume of transpyloric flow pulses. Subtotal transection maintained pre-transection timing and was associated with normal patterns of transpyloric flow and emptying. CONCLUSIONS: Our results indicate that a muscle bridge is capable of maintaining normal gastric emptying and the coordination of antral with pyloric contractions. We propose that antropyloric coordination is maintained by transmission of neural signals through the muscle bridge.

Anastomosis, Surgical↗

PubMed1996

Esophageal motility and reflux testing. State-of-the-art and clinical role in the twenty-first century.

Esophageal function testing has an important place in the investigation of a significant proportion of patients with esophageal disorders. Appropriate application of these tests requires a proper understanding of their capabilities and limitations and careful primary assessment by other modalities. Esophageal manometry is most useful for assessing significant troublesome dysphagia in the absence of organic obstruction. Esophageal pH monitoring is an important adjunct to clinical assessment and endoscopy in the diagnosis of reflux disease. Although it is the gold standard for the measurement of esophageal acid exposure and assessment of the relationship of symptoms to reflux, there are weakness in both of these functions that should be understood when applying the test to the diagnosis of reflux disease.

Esophageal Motility Disorders↗

PubMed1996

The endoscopic assessment of esophagitis: a progress report on observer agreement.

BACKGROUND & AIMS: The study and management of reflux esophagitis require an endoscopic classification system founded on esophageal lesions that can be reproducibly identified. The aim of this study was to investigate interobserver agreement for the identification of endoscopic lesions typical of reflux esophagitis. METHODS: Paired comparisons of observers' descriptions were obtained. Seventeen endoscopists assessed 100 still images, and 42 endoscopists, including 13 endoscopists in training, assessed 23 endoscopic video recordings. In a third, ancillary study, using a simpler evaluation sheet, 219 gastroenterologists recorded their assessments of 20 still images. RESULTS: The agreement between endoscopists was similar for still images and video recordings. Agreement between experienced endoscopists was acceptable to good for recognition of minimal changes (erythema, friability, mucosal edema; kappa = 0.46 to kappa = 0.8), mucosal breaks (discretely, demarcated areas of slough or erythema; kappa = 0.84), and complications (ulceration, kappa = 0.92; stricturing, kappa = 0.80; columnar metaplasia, kappa = 0.81), although there was poor agreement when the circumferential extent and number of mucosal breaks were assessed. However, total circumferential extent of the mucosal break had a kappa value of 0.59. Agreement between inexperienced endoscopists was poor for recognition of minimal changes but was good for recognition of complications (kappa, 0.70-0.90). CONCLUSIONS: Endoscopists can identify mucosal breaks confined to a mucosal fold and lesions that extend throughout the esophageal circumference. Complications of reflux disease can be reproducibly recorded. Criteria for assessing the number of mucosal breaks and their radial extent must be defined more clearly, as must the features of minimal change esophagitis.

Esophagitis↗

PubMed1996

Hyperglycaemia affects proximal gastric motor and sensory function in normal subjects.

OBJECTIVE: Hyperglycaemia delays gastric emptying in normal subjects and patients with diabetes mellitus by uncertain mechanisms and may affect the perception of somatic sensations. The effects of hyperglycaemia on the motor function of the proximal stomach and the perception of gastric distension were evaluated in normal subjects. DESIGN: Paired studies were performed in randomized order in 10 healthy volunteers on separate days during euglycaemia and hyperglycaemia (blood glucose approximately equal to 15 mmol/l). METHODS: With a barostat and a balloon positioned in the proximal stomach, tasting subjects underwent a stepwise gastric distension. Each 2 mmHg step was maintained at a constant pressure for 2 min. The volume of the barostat balloon was measured and perception of the sensations of fullness, desire to belch, nausea, abdominal discomfort and hunger was scored at each step. RESULTS: Hyperglycaemia was associated with an increase in proximal gastric compliance (P < 0.01) evident from 2 mmHg above basal intragastric pressure. Perception scores for the sensations of nausea and desire to belch were greater during hyperglycaemia than euglycaemia (P < 0.05) in relation to both pressure at each step and volume. Hyperglycaemia did not affect perception of the sensations of abdominal discomfort, fullness or hunger. CONCLUSIONS: Hyperglycaemia increases proximal gastric compliance, reflecting a reduction in gastric tone. This may contribute to the previously observed delay in gastric emptying associated with hyperglycaemia. Hyperglycaemia appears to increase the perception of some of the sensations induced by gastric distension.

Abdominal Pain↗

PubMed1996

Effects of glyceryl trinitrate on the pyloric motor response to intraduodenal triglyceride infusion in humans.

The retardation of gastric emptying induced by infusion of triglyceride into the small intestine is associated with suppression of antral pressure waves and stimulation of basal pyloric tone in combination with phasic pressure waves localized to the pylorus. The role of nitric oxide (NO) mechanisms in the control of pyloric motility was evaluated in 12 healthy male subjects (21-43 years), using the NO donor glyceryl trinitrate (GTN). Antropyloric pressures were measured with a manometric assembly incorporating nine sideholes, spanning the antrum and proximal duodenum, and a pyloric sleeve sensor. On separate days, an intraduodenal triglyceride infusion (10% intralipid at 1 mL min-1) was started during antral phase I activity and continued for 60 min. On one of the days GTN (600 micrograms) was given sublingually 20 min after start of the triglyceride infusion. The tonic pyloric motor response to triglyceride [5.6 (SEM 0.8,) vs. 2.7 (1.3) mmHg, P < 0.001] and both the number 3.2 (0.2) vs. 2.2 (0.2) min-1, P < 0.05] and amplitude [40 (4) vs. 27 (5) mmHg, P < 0.05] of phasic isolated pyloric pressure waves were reduced by GTN. These observations suggest that NO mechanisms are involved in the regulation of pyloric motor activity in humans.

Adolescent↗

PubMed1996

Motor events underlying gastro-oesophageal reflux in ambulant patients with reflux oesophagitis.

Information on the mechanism of gastro-oesophageal reflux in patients with reflux disease is limited largely to studies in resting recumbent subjects. Evidence exists that both posture and physical activity may influence reflux. The aim of this study was to investigate reflux mechanisms in ambulant patients with reflux oesophagitis. Concurrent ambulatory oesophageal manometry and pH monitoring were performed in 11 ambulant patients with erosive oesophagitis. Lower oesophageal sphincter (LOS) pressure was monitored with a perfused sleeve sensor. Recordings were made for 90 min before and 180 min after a meal. At set times patients sat in a chair or walked. LOS pressure was < or = 2 mmHg at the time of reflux for 98% of reflux episodes. Transient LOS relaxation was the most common pattern overall and the predominant pattern in seven patients, whilst persistently absent basal LOS pressure was the most common pattern in four patients. The pattern of LOS pressure was not altered by the presence of hiatus hernia or by walking. Straining occurred at the onset of 31% of acid reflux episodes but often followed the development of an oesophageal common cavity. The occurrence of straining was not influenced by walking. In ambulant patients with reflux oesophagitis: (1) LOS pressure is almost always absent at the time of reflux, usually because of transient LOS relaxation, (2) persistently absent basal LOS pressure is an important mechanism of reflux in a few patients, (3) straining may help to induce acid reflux in a variable proportion of occasions and may in some instances be a response to gas reflux, and (4) walking does not influence the occurrence of reflux or its mechanisms.

Adult↗

PubMed1996

Intraluminal micromanometry: an evaluation of the dynamic performance of micro-extrusions and sleeve sensors.

Conventional manometric techniques are unsuitable for studies in premature infants and small laboratory animals. We have therefore developed silicone rubber 5-lumen and 10-lumen micromanometric extrusions with an o.d. 2.0 mm and lumina of 0.35 mm i.d. This study evaluates the suitability of microextrusions for intraluminal perfusion manometry. Pressure offset, post-occlusion pressure rise rate and sphincter model studies were used to assess the manometric performance of the extrusions and a miniature sleeve sensor (25 mm long) at infusion rates of 0.01-0.1 mL min-1. Micro-extrusions (5-lumen/10-lumen, respectively) had offsets (per 100 cm of length) of 3.8/5.0 mmHg at 0.01 mL min-1 and 25.6/26.2 mmHg at 0.1 mL min-1 and rise rates (in 160 cm lengths) of 64/43 mmHg sec-1 at 0.01 mL min-1 and 330/224 mmHg sec-1 at 0.1 mL min-1. Infusion rates 0.025 mL min-1 produced rise rates 100 mmHg sec-1. The miniature sleeve sensor had minimal resistance to perfusion, rise rates of 3 mmHg sec-1 at 0.01 mL min-1 and 23 mmHg sec-1 at 0.1 mL min-1 and recorded pressure as accurately as a side hole. We conclude that the performance of micromanometric extrusions and sleeves is sufficient for intraluminal perfusion manometry.

Animals↗

PubMed1996

The Cathlocator: a novel non-radiological method for the localization of enteral tubes.

Safe placement of nasogastric tubes requires reliable positioning of the tip of the tube within the stomach. Radiology and aspiration are currently used to confirm tube position, but suffer from significant problems of cost and efficacy, respectively. We have developed a novel method to locate the position of a catheter tip within the body, using the detection of low energy electromagnetic field generated in a coil located in the catheter with an external hand-held unit (Cathlocator). In vitro, the unit detected the distance of the coil from the detector with an accuracy of 0.1 cm over a range of 4-12 cm. In vivo studies were performed in 11 healthy volunteers using a purpose-built manometric assembly that incorporated the signal generating coil in its tip. In all subjects the Cathlocator showed the position of the signal generating coil to be cranial to the xiphisternum when manometric and transmucosal potential difference criteria showed it to be located above the lower oesophageal sphincter. When the coil was within the stomach, the Cathlocator identified its position within the epigastric, umbilical and left hypochondrial regions of the abdomen. The distance of the coil from the surface was significantly greater when in the duodenum mean (+/- s.e.m. 7.6 +/- 0.3 cm; P < 0.001) and oesophagus (8.6 +/- 0.2 cm; P < 0.002) than the stomach (5.0 +/- 0.4 cm). In one subject studied twice there was a close correlation between the location and depth measured by the device on each occasion. The Cathlocator is a novel non-radiological device that has the potential to be useful in the placement of gastrointestinal catheters.

Adult↗