Biomedical subjects

T I Omari

Publications and source records attributed to T I Omari.

At least 19 recordsLinked to original sources

PubMed2005

Assessment of the rectoanal inhibitory reflex in preterm infants with delayed meconium passage.

BACKGROUND: There is an inverse relationship between gestational age, birth weight and the time of first neonatal bowel movement. The authors hypothesized that delayed passage of meconium might result from a delayed maturation of the recto-anal inhibitory reflex (RAIR) in premature infants. OBJECTIVE: To evaluate whether the RAIR is absent in very preterm infants 28-32 weeks postmenstrual age with delayed meconium production. STUDY DESIGN: Anorectal manometry was performed in 10 preterm infants (seven male) with delayed meconium production (no meconium in the first 48 hours). Median postmenstrual age was 30 weeks (28-31 weeks). Birth weight ranged from 780 to 1930 g (median, 1395 g). A micromanometric assembly (outer diameter, 2.0 mm) was used which incorporated a 1.5-cm-long sleeve sensor for measurement of resting anal sphincter pressure and relaxation. Four side-holes recorded anal and rectal pressures. Rectal distension was performed with direct air insufflation to elicit the RAIR. RESULTS: The time from birth to passage of meconium ranged from 48 to 105 hours (median, 82 hours). The mean anal sphincter pressure, rectal pressure, and anal sphincter oscillation frequency were 22.0 +/- 5.0 mm Hg, 6.9 +/- 2.0 mm Hg, and 9.8 +/- 1.9/min, respectively. A normal RAIR was elicited in all infants. CONCLUSION: Anorectal manometry recordings in premature infants with delayed passage of meconium showed normal anorectal pressures and a normal RAIR, suggesting that delayed meconium passage is not related to the absence of a RAIR.

Anal Canal↗

PubMed2004

Nasopharyngeal pH monitoring in chronic sinusitis patients using a novel four channel probe.

OBJECTIVE: To determine the prevalence of acid reflux into the nasopharynx in patients with chronic sinusitis. STUDY DESIGN: Prospective study of patients presenting to a specialist rhinology practice with chronic sinusitis. METHODS: Forty patients with chronic sinusitis underwent ambulatory 24 hour pH testing. The mean age of the patients was 56.3 years (25 Female, 15 Male). The studies were performed using a specially developed bifurcated 4 channel pH probe, incorporating 2 circumferential sensors positioned at the naso- and hypo-pharynx, and 2 unidirectional sensors positioned at the proximal and distal esophagus. RESULTS: The circumferential band sensors yielded a stable recording largely free of artefact allowing meaningful recordings to be obtained from thirty-seven patients. Twelve patients (32.4%) were diagnosed with gastroesophageal reflux. A total of 809 reflux episodes were recorded. Of these, 596 (73.7%) reached the distal esophagus, with 187 (23.1%) and 24 (3.0%) reaching the proximal esophagus and hypopharynx respectively. Only 2 episodes (0.2%) were recorded in the nasopharynx. This occurred in 2 of 37 patients (5%). CONCLUSIONS: Acid reflux into the nasopharynx is a rare event in patients with chronic sinusitis even though a significant proportion (32.4%) have abnormal 24 hour pH studies. It is likely that alternative mechanisms other than direct acid contact are involved in the pathogenesis of chronic sinusitis.

Adult↗

PubMed2003

Maturation of the rectoanal inhibitory reflex in very premature infants.

OBJECTIVE: To characterize anal sphincter function in very premature infants < or =30 weeks' postmenstrual age (PMA) and to evaluate the time of maturation of the rectoanal inhibitory reflex (RAIR) by using a sleeve catheter. STUDY DESIGN: Anorectal manometry was performed in 16 healthy neonates (nine girls) with a mean PMA of 29 weeks (range, 27-30 weeks) and a birth weight of 640 to 1590 g (median, 1220 g) with a micromanometric assembly (outer diameter, 2.0 mm). The assembly incorporated a 1.5-cm-long sleeve sensor for measurement of resting anal sphincter pressures and relaxation, and four side holes recorded anal and rectal pressures. Rectal distention was performed with direct air insufflation to elicit the RAIR. RESULTS: The mean anal sphincter pressure, rectal pressure, and anal sphincter oscillation frequency were 24.5+/-11.4 mm Hg, 6.5+/-4.8 mm Hg, and 11.1+/-2.3/min, respectively. A normal RAIR could be elicited in 13 (81%) infants studied. In two infants, the RAIR could not be elicited because of a low anal sphincter pressure of only 5 mm Hg. In the other child, no RAIR was seen despite the repeated insufflation of at least 5 mL of air. CONCLUSION: The majority (81%) of premature infants older than 26 weeks' PMA have normal anorectal pressures and a normal RAIR.

Anal Canal↗

PubMed2003

Multipoint measurement of intragastric pH in healthy preterm infants.

BACKGROUND: The diagnostic use of 24 hour oesophageal pH monitoring in infants is controversial because of the impact of feed buffering of gastric acidity. AIM: To re-evaluate the effect of feeding on gastric pH and reflux using multipoint pH measurements. SUBJECTS: Fifteen healthy premature infants fed every four hours. METHODS: Oesophageal pH and intragastric pH at 3, 6, and 9 cm below the lower oesophageal sphincter were simultaneously measured using a four channel pH probe for four hours after bolus feeding. Parameters of pH were compared for the different levels within the stomach. During reflux episodes, the nadir pH was compared with intragastric pH at all levels. RESULTS: The proximal stomach was more significantly buffered by feeding and slower to re-acidify postprandially than the mid and distal stomach (42.2% of the time at pH < 4 compared with 58.7% and 55.7% respectively). During 27 of 62 gastro-oesophageal reflux episodes, nadir oesophageal pH was lower than the pH of the proximal stomach but always equal to or higher than the pH of the distal stomach. CONCLUSIONS: These data indicate that previous studies may have overestimated the effect of feeding on gastric acidity and reflux.

Enteral Nutrition↗

PubMed2002

Patterns of antropyloric motility in fed healthy preterm infants.

BACKGROUND: Antropyloric motility is important for regulation of gastric emptying and has not been adequately characterised in premature infants. AIM: To evaluate fed patterns of antropyloric motility in premature infants. SUBJECTS: Forty three healthy premature infants, 30-38 weeks of postmenstrual age. METHODS: Postprandial antropyloric motility was measured using a micromanometric feeding assembly (outer diameter 1.8 mm) incorporating a pyloric sleeve sensor. The occurrence of isolated pyloric pressure waves (IPPWs) and antral pressure wave sequences (PWSs) was characterised. Sequences were further classified as being antegrade, synchronous, antegrade-synchronous, and retrograde according to the direction of propagation. RESULTS: A total of 7289 pressure wave events were recorded, 48% IPPWs and 52% PWSs (18% antegrade, 12% synchronous, 13% antegrade-synchronous, 2% retrograde, and 7% undefined). IPPWs predominated in the first postprandial hour, peaking at 30-60 minutes. PWSs predominated in the period after one hour postprandially. Mean (SEM) half gastric emptying time was 42 (4) minutes. CONCLUSIONS: Monitoring of antropyloric motor patterns in healthy premature infants indicates that the neuroregulatory mechanisms responsible for the coordination of antropyloric motility and gastric emptying are well developed by 30 weeks of postmenstrual age.

Female↗

PubMed2002

Mechanisms of gastro-oesophageal reflux in preterm and term infants with reflux disease.

BACKGROUND: Transient lower oesophageal sphincter relaxation (TLOSR) is the predominant mechanism of gastro-oesophageal reflux (GOR) in healthy infants but the mechanisms of GOR in infants with GOR disease (GORD) are poorly understood. AIMS: To measure the occurrence of TLOSR, GOR, and gastric emptying (GE) rate in preterm and term infants with GORD. PATIENTS: Thirty six infants were studied and grouped as normals or GORD based on a routine clinical assessment and confirmation of an assessment of GORD by reflux symptom charts and oesophageal pH monitoring. METHODS: A micromanometric assembly incorporating a micro pH electrode recorded oesophageal motility and pH. GE rate was determined using the (13)C-octanoic acid breath test. RESULTS: TLOSR was the predominant mechanism of GOR, triggering 50-100% of GOR episodes (median 91.5%). Abdominothoracic straining significantly increased the occurrence of GOR in association with TLOSR. In infants with GORD, the number of TLOSRs overall was similar to normals but the proportion of TLOSRs accompanied by acid GOR was significantly higher than in normals (16.5% v 5.7%, respectively; p<0.001). Infants with GORD had a similar GE rate to normals. CONCLUSIONS: In infant GORD, acid reflux associated TLOSRs are abnormally common and likely to be a major contributing factor to the pathophysiology of GORD. Infants with GORD do not have delayed GE.

Analysis of Variance↗

PubMed2001

Pathophysiological mechanisms of gastroesophageal reflux disease in children.

Gastroesophageal reflux (GER) is an extremely common pediatric problem, but only in the past few years have we developed a better understanding of its pathophysiology. This is related to the wider use of investigative tools such as flexible endoscopy, 24-hour pH monitoring, and more recently, micromanometric methods and noninvasive breath tests, which have been particularly useful in infants. This paper reviews our current understanding of the esophageal and gastric mechanisms contributing to the pathophysiology of GER. In this context, we also highlight areas where new therapeutic approaches may be beneficial.

Child↗

PubMed2001

Characterization of anorectal pressure and the anorectal inhibitory reflex in healthy preterm and term infants.

OBJECTIVES: To evaluate anorectal motor function in healthy premature and term infants with the use of micromanometric techniques. STUDY DESIGN: Anorectal manometry was performed in 22 healthy neonates (9 female) with a mean postmenstrual age of 32 weeks (range, 30 to 38 weeks) with a micromanometric anorectal assembly (od 2.0 mm). The assembly incorporated a 2-cm-long sleeve sensor for measurement of resting anal sphincter pressures and relaxation, and 4 sideholes recorded anal and rectal pressures. Rectal distension was performed with a latex balloon or direct air insufflation to elicit the anorectal inhibitory reflex (AR). RESULTS: The mean anal sphincter pressure, rectal pressure, and rhythmic wave frequency were 40 mm Hg (range, 7 to 65 mm Hg), 11 mm Hg (range, 1 to 27 mm Hg), and 10/min (range, 8 to 14/min), respectively. A normal AR could be elicited in 21 of the 22 infants studied. CONCLUSION: An anorectal micromanometric sleeve catheter is suitable for use in evaluating anorectal pressures in preterm and term neonates. Insufflation of air without the use of a balloon to elicit the AR is reliable and suitable for use in infants <34 weeks. Premature infants older than 30 weeks' postmenstrual age have normal anorectal pressures and a normal AR.

Anal Canal↗

PubMed2000

Assessment of gastric emptying in the mouse using the [13C]-octanoic acid breath test.

1. Gastric emptying studies in small laboratory animals are hampered by the deficiency of a technique that is non-invasive and repeatable. The aim of the present study was to adapt the non-invasive [13C]-octanoic acid breath test, which has been validated in humans, to assess both liquid and solid gastric emptying in the mouse. 2. Gastric emptying rates were investigated for a liquid meal (Intralipid; Kabi Pharmacia AB, Stockholm, Sweden; n = 7) and two solid meals (egg yolk and mouse chow; n = 7) incorporating [13C]-octanoic acid. All meals were analysed for natural enrichment of [13C]. Mathematical analysis of the 13CO2 excretion rate allowed the determination of gastric emptying parameters. 3. Gastric emptying of Intralipid was more rapid than egg yolk (P < 0.0001). Gastric emptying of mouse chow could not be assessed due to intragastric separation of [13C]-octanoic acid and natural [13C] enrichment of the pellet. 4. The [13C]-octanoic acid breath test can reproducibly assess both liquid and solid gastric emptying non-invasively in the mouse. This method can now be used to assess gastric emptying in drug studies and disease studies for which there are established mouse models.

Animals↗

PubMed2000

Evaluation of miniature manometric techniques for the measurement of esophageal body pressure waves.

BACKGROUND AND AIMS: Perfused miniature manometric assemblies with lumina of 0.4-0.5 mm i.d. have been developed. Reduced luminal size offers the advantages of reduced assembly bulk and increased assembly complexity with greater numbers of lumina and lower manometric infusion volumes because of a slower perfusion rate. This study investigated the recording fidelity of miniature manometric assemblies in the measurement of esophageal peristalsis. METHODS: Four miniature manometric assemblies, each containing manometric lumina of either 0.4 or 0.5 mm i.d., were evaluated at 100 and 180 cm lengths. The fidelity of miniature manometric luminal recordings were evaluated in vivo during esophageal peristalsis by using a simultaneous comparison with the standard lumina and an intraluminal strain gauge. RESULTS: During esophageal peristalsis, miniature manometric lumina recorded the peak amplitude of pressure waves, with an accuracy at perfusion rates of 0.04 mL/min (0.4 mm, i.d.) and 0.15 mL/min (0.5 mm, i.d.). CONCLUSION: Miniature manometric assemblies of lengths that are practical for use in humans are suitable for recording esophageal peristalsis.

Adult↗

PubMed2000

Reflux in children.

Gastro-oesophageal reflux (GOR) is an extremely common paediatric problem that often runs a harmless and self-limited course. Physiological GOR however can lead to marked parental anxiety, many unnecessary investigations and often unwarranted and potentially harmful therapeutic interventions. Our ability to better define GOR and gastro-oesophageal reflux disease (GORD) has improved in the past 15 years with a better understanding of the pathophysiology in infants and children due to the development and wider use of flexible endoscopy, 24-hour oesophageal pH monitoring and, more recently, the use of micromanometric methods for studying oesophageal motility. This will be further enhanced in the future with the development of non-invasive breath testing to study gastrointestinal motility and the use of electrical impedance to study fluid movement. Our therapeutic interventions have also improved particularly in the areas of acid suppression, improved surgical techniques and most recently laparoscopic fundoplication. This chapter reviews these advances in the paediatric area especially with regard to pathophysiology, diagnostic testing and therapeutic intervention.

Age Factors↗

PubMed2000

Behavior and gastroesophageal reflux in the premature neonate.

BACKGROUND: The belief that behavioral observations assist in the clinical diagnosis of gastroesophageal reflux (GER) disease in premature neonates has not been formally tested. The purpose of this study was to determine whether esophageal acidification was associated with a recognizable pattern of behavioral changes in these infants. METHODS: The behavior of 14 healthy premature infants was recorded by a video camera while esophageal pH was simultaneously monitored. For each of 20 acid GER episodes recorded, a 10-minute video epoch, encompassing the onset of acid GER and lasting at least 4 minutes after the onset of GER, was examined. Two independent observers each scored reflux-associated epochs of "general" infant behavior and behavior previously shown to be indicative of reflux in normal term infants. RESULTS: The occurrence of esophageal acidification due to reflux did not significantly alter scores for general behavior. Infants frequently demonstrated reflux-specific behavior, including discomfort, head retraction, and mouthing; however, none of these behavioral patterns was temporally associated with the occurrence of acid GER. CONCLUSIONS: These data indicate that reflux-specific behavioral criteria, established in older term infants, may be inappropriate as diagnostic criteria for GER in premature neonates and may lead to the unnecessary use of antireflux therapy.

Behavior↗

PubMed2000

Evaluation of multiple-point measurement of sphincter of Oddi motility in the Australian brush-tailed possum.

Manometric assembly diameter is a major limitation on the number of perfused manometric recording points for recordings from the sphincter of Oddi (SO). We evaluated novel polyimide manometric assemblies whereby four recording channels were incorporated in an overall assembly diameter of 0.8 mm. Over the very low range of perfusion rates tested (0.005-0.04 ml/min), the assemblies had pressure offsets attributable to water perfusion from 2 to 23 mmHg and pressure rise rates from 20 to 163 mmHg/s. In six anesthetized Australian brush-tailed possums, manometric recordings from the SO showed a significant reduction in the recorded peak amplitude of pressure waves with perfusion rates below 0.02 ml/min. The pressure profile of the sphincter was found to be asymmetric, and phasic wave propagation patterns were complex (antegrade 35.6%, "mixed" 64.4%). In conclusion, accurate multipoint SO manometry in the possum can be performed with micromanometric assemblies at very low perfusion rates to give a more complete understanding of SO mechanics. These methods are also potentially applicable to perfusion manometry in other small laboratory animals such as mice.

Animals↗

PubMed1999

Characterization of esophageal body and lower esophageal sphincter motor function in the very premature neonate.

OBJECTIVES: To characterize esophageal body and lower esophageal sphincter (LES) motor function in very premature infants. STUDY DESIGN: Esophageal manometry was performed in 12 very premature infants of 26 to 33 weeks' postmenstrual age (PMA) (body weights of 610-1360 g). Esophageal motor patterns were recorded for 30 minutes with a perfused micromanometric sleeve assembly (outer diameter, 2.0 mm). RESULTS: Esophageal pressure waves triggered by dry swallows were predominantly (84%) peristaltic in propagation sequence. All infants showed tonic LES contraction; the mean resting LES pressure (LESP) for individual infants ranged from 5.0 +/- 4.1 mm Hg to 20.0 +/- 4.8 mm Hg. In all infants the LES relaxed (duration, 5.8 +/- 3.0 seconds; nadir pressure, 1.8 +/- 2.6 mm Hg) in response to pharyngeal swallows. Transient LES relaxations (TLESRs) (duration, 21.7 +/- 8.7 seconds; nadir pressure, 0.1 +/- 1.8 mm Hg) occurred on average 2.6 +/- 1.6 times per study; 86% of these relaxations triggered esophageal body common cavity events known to be associated with gastroesophageal reflux. CONCLUSIONS: Esophageal motor function is well developed in very premature infants. Our data also suggest that TLESR is the predominant mechanism of reflux in these babies.

Esophagogastric Junction↗

PubMed1999

Lower esophageal sphincter position in premature infants cannot be correctly estimated with current formulas.

OBJECTIVES: Strobel's formula (Esophageal length = 5 + 0.252 x Height) is frequently used as a guide for determining the distance from the nares to the lower esophageal sphincter (LES) in term infants. The aim of this study was to examine this relationship in premature infants. STUDY DESIGN: The distance from nares to LES was manometrically determined in 156 premature infants (26-40 weeks' postmenstrual age; body weights of 610-3050 g). The ability of body weight, height (body length), head circumference, and postmenstrual age to predict the manometrically determined LES position was evaluated with linear and non-linear regression analyses. RESULTS: Body weight and body length were the most predictive of distance from nares to LES (r(2) = 0.848 and 0.802, respectively). These relationships were non-linear and, in the case of body length, deviated substantially from Strobel's model. CONCLUSIONS: In premature neonates, a different formula is needed for prediction of the distance between nares and LES than that applied to term infants and children.

Anthropometry↗

PubMed1998

Mechanisms of gastroesophageal reflux in healthy premature infants.

OBJECTIVES: The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of healthy preterm infants. STUDY DESIGN: Esophageal motility was recorded for 2 to 3 hours after a feeding in 24 preterm infants, 31 to 38 weeks' postmenstrual age, by using a sleeveside hole micromanometric assembly incorporating a pH probe. RESULTS: Sixty acid GER episodes were recorded by pH probe, and 133 non-acid GER episodes were recorded manometrically by the presence of esophageal common cavities. Of the 193 GER episodes, 159 (82%) were associated with transient lower esophageal sphincter relaxation (TLESR). TLESRs were significantly longer in duration than single swallows (15.1 seconds vs 5.6 seconds, P < .001) and had lower nadir pressures (0.8 mm Hg vs 2.3 mm Hg, P < .001). A total of 3216 esophageal body pressure waves were analyzed; 70% of swallow-induced pressure waves were peristaltic in sequence compared with 5% of swallow-unrelated pressure waves. During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences. CONCLUSIONS: In healthy preterm infants, TLESRs are the predominant mechanism underlying GER, and esophageal clearance mechanisms are well developed by at least 31 weeks' postmenstrual age.

Cohort Studies↗

PubMed1998

A comparison of micromanometric and standard manometric techniques for recording of oesophageal motility.

Perfused micromanometric assemblies with an outer diameter of 2 mm or less have been developed for use in premature infants and small laboratory animals. Such assemblies offer advantages with regard to subject comfort and low perfusion rates that make them attractive for use in adults. The aim of this study was to investigate the recording fidelity of micromanometric assemblies in the measurement of oesophageal peristalsis in adults. Two micromanometric assemblies with an outer diameter of 1.8-2.0 mm and a length suitable for use in adults (165 cm), and containing micromanometric lumina of 0.28-0.35 mm i.d. and a standard lumen of 0.6-0.75 mm i.d. were evaluated. Each assembly was tested by measurement of pressure rise rate in response to sudden occlusion, and in vivo during oesophageal peristalsis by simultaneous comparison with an intraluminal strain gauge. At perfusion rates of 0.01-0.15 mL min-1 microlumina achieved pressure rise rates of 21-430 mmHg sec-1 that were comparable to 37-390 mmHg sec-1 for the standard lumina perfused at 0.15-0.6 mL min-1. During oesophageal peristalsis, micromanometric lumina recorded the occurrence and timing of all pressure waves accurately when compared with standard lumina and the microtransducer. However, microlumina under-recorded pressure wave amplitude to varying degrees dependent upon perfusion rate although the performance of microlumina could be improved to that of the standard lumen by shortening their length to 70 cm. Micromanometric assemblies are suitable for recording oesophageal peristalsis in adults although there is some impairment of absolute manometric fidelity. Fidelity can be improved by minimizing total assembly length.

Adult↗

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↗