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Biomedical subjects

R K Mittal

Publications and source records attributed to R K Mittal.

At least 37 records · Page 2Linked to original sources
PubMed1998

Distension-related responses in circular and longitudinal muscle of the human esophagus: an ultrasonographic study.

Both circular muscles (CM) and longitudinal muscles (LM) of the esophagus participate in peristalsis. Various measurement techniques have yielded conflicting information as to the temporal correlation between contraction in the two muscle layers. High-frequency intraluminal ultrasound (HFIUS) is a novel technique to detect contraction of LM and CM of the esophagus. We investigated the temporal correlation between the CM and LM contraction during ascending excitatory and descending inhibitory reflexes using HFIUS. A manometric catheter equipped with two balloons and a 12.5-MHz ultrasound transducer catheter was used to study 10 normal healthy subjects. The changes in muscle thickness and pressure, proximal and distal to esophageal distension, were recorded at 5 and 10 cm above the lower esophageal sphincter (LES). The esophageal distension induced an increase in pressure and an increase in muscle thickness of both CM and LM layers proximal to the distension site. The onset of increase in muscle thickness and peak muscle thickness in two layers occurred at the same time. There was a close temporal correlation between the changes in pressure and changes in muscle thickness. Atropine inhibited the distension-related pressure and muscle thickness increase in both layers. Distal to the esophageal distension, there was no change in pressure but a decrease in the thickness of the two muscle layers. The decrease in muscle thickness of the two layers occurred at the same time. The responses of the two muscle layers to distension were similar at 5- and 10-cm sites above the LES. HFIUS is a relatively noninvasive technique to study the LM layer response during peristalsis in vivo. Our data indicate that the two muscle layers may contract and relax together during distension-related peristaltic reflexes in the esophagus.

Adult↗
PubMed1998

Acinetobacter sepsis in newborns.

OBJECTIVE: To evaluate the clinico-epidemiological profile of Acinetobacter sepsis in neonates. DESIGN: Retrospective study. SETTING: Level II Neonatal Care Unit. SUBJECTS: 79 neonates with blood culture positive for Acinetobacter. METHODS: Relevant information was collected on a predesigned proforma from the case records and analyzed for clinical and epidemiological characteristics. RESULTS: The incidence of Acinetobacter septicemia was 11.1/1000 live births. Fifty-five babies were hospital born, 24 were outborn. Out of these, 64.6% babies were born at term and 40.5% had a birth weight of 2500 g or more. A cluster of 53 cases was seen between May and September 1995. In cases with early onset sepsis (onset < 7 days of postnatal age), difficulty in breathing (n = 54), chest retraction (n = 35) and refusal to feed (n = 46) were seen more commonly as compared to late onset sepsis (p < 0.05). Complications observed included meningitis, bleeding manifestations and necrotising enterocolitis in three, six and five babies, respectively. The organism was sensitive to ciprofloxacin (96.2%), amikacin (92.4%) and gentamicin (87.3%). A response rate of 52.4% was observed with Ciprofloxacin in babies not responding to cefotaxime and amikacin combination. The overall mortality was 13.9%. CONCLUSION: Nosocomial Acinetobacter sepsis may affect fullterm, appropriate for gestational age babies. Clinical presentation is indistinguishable from Gram negative septicemia. Life threatening complications can also occur. Ciprofloxacin may prove to be useful drug in resistant cases.

Acinetobacter Infections↗
PubMed1997

Atropine inhibits gastric distension and pharyngeal receptor mediated lower oesophageal sphincter relaxation.

BACKGROUND: Atropine decreases the frequency of transient lower oesophageal sphincter relaxation (TLOSR) through an unknown mechanism. Gastric distension and pharyngeal receptor excitation are two possible sources for the afferent stimulus responsible for TLOSR. AIMS: To determine whether atropine affects gastric distension induced TLOSR and pharyngeal receptor mediated lower oesophageal sphincter (LOS) relaxation. METHODS: Oesophageal manometry and pH recordings were performed in 10 healthy volunteers on two separate days in the postprandial setting, following either atropine (15 micrograms/kg intravenous bolus and 4 micrograms/kg/h as a maintenance dose) or placebo. Pharyngeal receptor mediated LOS relaxation was studied in nine subjects by rapid injection of minute amounts of water (0.05, 0.1, 0.2, 0.3, and 0.4 ml) in the pharynx before and after atropine. Gastric distension mediated TLOSR was studied in eight subjects by insufflating the stomach with 300, 600 and 900 ml of CO2 before and after atropine. RESULTS: Atropine reduced the frequency of spontaneous gastro-oesophageal reflux and TLOSR compared with placebo (p < 0.05). Pharyngeal stimulation resulted in bolus volume dependent LOS relaxation. Atropine decreased the frequency and amplitude of pharyngeal receptor mediated LOS relaxation at bolus volumes of 0.05, 0.1, and 0.2 ml. Gastric distension resulted in intermittent episodes of TLOSR. The frequency of gastric distension induced TLOSR was significantly decreased by atropine. CONCLUSION: (1) Atropine reduces the frequency of spontaneous reflux and TLOSR in normal subjects; and (2) gastric distension induced TLOSR and pharyngeal receptor mediated LOS relaxation is inhibited by atropine.

Adult↗
PubMed1997

Frequency of gastroesophageal reflux events induced by pharyngeal water stimulation in young and elderly subjects.

Earlier studies have shown that isolated complete lower esophageal sphincter (LES) relaxation occurs as a result of pharyngeal water stimulation. Association of these relaxations with gastroesophageal reflux has not been studied systematically. Our aim was to determine this association in young and elderly subjects during precibal and postprandial periods. We studied 8 young subjects and 10 elderly subjects for 1 h before and 2 h after a 1,000-cal meal. In both groups, during the precibal period, negligible LES relaxation induced by pharyngeal water stimulation resulted in gastroesophageal reflux. In the postprandial period, gastroesophageal reflux events occurred after 16% of pharyngeal water injections in young subjects and after 44% in elderly subjects (P < 0.05). Intraabdominal length of the LES in elderly subjects was significantly shorter compared with younger subjects (P < 0.05). We conclude that gastroesophageal reflux events induced by pharyngeal water stimulation in the postprandial period are significantly increased compared with those of the precibal period and are significantly more prevalent in the elderly compared with the young. These differences seem to be associated with a significantly shorter intra-abdominal segment of the LES in the elderly.

Adult↗
PubMed1997

Asymmetry of lower esophageal sphincter pressure: is it related to the muscle thickness or its shape?

Lower esophageal sphincter (LES) pressure shows axial and circumferential asymmetry, the reasons for which are not clear. Our aim was to determine whether the muscle thickness and shape of the LES were the reasons for the axial and circumferential asymmetry in the LES pressure. High-frequency, catheter-based intraluminal ultrasonography was performed to obtain images of the human LES and esophagus. Station pull-through manometry was performed to record the axial and circumferential asymmetry of LES pressure. Circular and longitudinal muscle were thicker in the LES compared with in the esophagus. There was a close correlation between the axial asymmetry in LES pressure and circular muscle thickness. The thickness of LES muscle increased and decreased with an increase and decrease in the LES pressure, respectively. The circumferential asymmetry in resting LES pressure was related to the noncircular shape of the LES. A swallow-induced LES relaxation was followed by its contraction. During the contraction phase, the LES and esophagus showed relative symmetry in pressure and shape. We conclude that the axial asymmetry of LES pressure is explained by its muscle thickness. On the other hand, circumferential asymmetry is related to the noncircular shape of the LES.

Adult↗
PubMed1996

Characteristics of lower esophageal sphincter relaxation induced by pharyngeal stimulation with minute amounts of water.

BACKGROUND & AIMS: Injection of minute amounts of water in the pharynx leads to a long-duration lower esophageal sphincter (LES) relaxation that is an important feature of a transient LES relaxation. The aims of this study were to determine if a pharyngeal stimulus-induced LES relaxation is associated with crural diaphragm inhibition, esophageal common cavity, and acid reflux in normal subjects. METHODS: Esophageal and LES pressure, crural diaphragm electromyographs, and pH were recorded in the fasting and postprandial states in normal subjects. The pharynx was stimulated by injection of water at bolus volumes of 0.05 and 0.1 mL and then in 0.1-mL increments. RESULTS: Pharyngeal stimulation induced a long-duration LES relaxation in the absence of swallow and esophageal peristalsis. In the fasting state, none of the LES relaxations induced by pharyngeal stimulation were associated with inhibition of crural diaphragm, esophageal common cavity, and acid reflux. In the postprandial periods, only 8% of the pharyngeal stimuli resulted in crural diaphragm inhibition and esophageal common cavity. Esophageal reflux was found only at the times of simultaneous LES and crural diaphragm relaxation. CONCLUSIONS: Stimulation of the pharynx has different effects on the LES and crural diaphragm. Relaxation of crural diaphragm along with LES relaxation is essential for the occurrence of gastroesophageal reflux in normal subjects.

Adult↗
PubMed1995

Inhibition of resting lower esophageal sphincter pressure by pharyngeal water stimulation in humans.

BACKGROUND/AIMS: Normal inhibition of lower esophageal sphincter (LES) tone occurs during swallowing and belching. However, it is known that it may occur independently of these functions. The aim of this study was to characterize the effect of pharyngeal water stimulation on resting LES pressure. METHODS: The effect of rapid-pulse and slow continuous intrapharyngeal injection of minute increments of water on the resting tone of the upper and LES of 14 healthy young volunteers was evaluated by concurrent manometry, submental electromyography, and respirography. RESULTS: At a threshold volume, pharyngeal water injection induced an isolated LES relaxation in all volunteers. The threshold volume inducing LES relaxation by rapid-pulse injection, 0.16 +/- 0.01 mL, was significantly lower than that with slow continuous injection (0.5 +/- 0.05 mL) (P < 0.05). The duration and magnitude of LES relaxation were not volume dependent. The duration of LES relaxation induced by rapid-pulse injection was significantly longer than that of swallows. CONCLUSIONS: Minute amounts of liquid injected into the pharynx induce LES relaxation different from that of the normal swallow. Neither the duration nor the magnitude of this relaxation is volume dependent. Whereas the contribution of this finding to the mechanism of transient LES relaxation remains to be ascertained, it may partially explain the variability of the basal LES pressure.

Adult↗
PubMed1995

Effect of atropine on the frequency of reflux and transient lower esophageal sphincter relaxation in normal subjects.

BACKGROUND & AIMS: Low basal lower esophageal sphincter (LES) pressure is believed to be an important mechanism of reflux. The effects of atropine on the frequency and mechanisms of gastroesophageal reflux under the experimental conditions of a low basal LES pressure in 13 normal subjects were studied. METHODS: LES pressure, esophageal pressures, esophageal pH, and crural diaphragm electromyogram were recorded simultaneously in the postprandial period for 30 minutes before and two 30-minute periods after the injection of atropine. RESULTS: Atropine reduced the basal LES pressure from 16.4 +/- 3 to 8.7 +/- 2 mm Hg. The frequencies of reflux in the control and two postatropine periods were 3.5 +/- 0.5, 0.4 +/- 0.2, and 0.8 +/- 0.3, respectively (P < 0.05). The frequencies of transient LES relaxations decreased from 3.5 +/- 0.5 in the control to 0.4 +/- 0.2 and 1.5 +/- 0.4 in the two postatropine periods (P < 0.05). Transient LES relaxation and associated inhibition of the crural diaphragm was the major mechanism of reflux under conditions of low LES pressure induced by atropine. CONCLUSIONS: Atropine-induced low LES pressure does not predispose to reflux in normal healthy subjects. Atropine reduces the frequency of reflux by its inhibitory effect on the frequency of transient LES relaxation.

Adolescent↗
PubMed1995

Influence of breathing pattern on the esophagogastric junction pressure and esophageal transit.

The esophagogastric junction (EGJ) is guarded by two sphincters, a smooth muscle lower esophageal sphincter (LES) and a skeletal muscle crural diaphragm. The LES relaxes in response to a swallow but the crural diaphragm does not. Since contraction of the crural diaphragm is affected by the pattern of breathing, the latter may also influence the EGJ pressure and swallow-induced EGJ relaxation. Our aims were to study the effects of alterations of the breathing pattern on the EGJ pressure, swallow-induced EGJ relaxation, and esophageal transport of liquid bolus. Manometric, electromyographic, and videofluoroscopic studies were performed in 12 healthy subjects. The subjects were trained in two types of breathing patterns, hyperventilation and partial expiration, using the visual biofeedback from their own respiratory waveform. Hyperventilation increased the frequency of inspiratory pressure oscillations at the EGJ without affecting the end-expiratory EGJ pressure. Partial expiration resulted in an increase in the end-expiratory EGJ pressure. Swallow-induced relaxation at the EGJ was markedly reduced during partial expiration. An inspiration during a swallow (control breathing and hyperventilation) caused transient interruption of flow across the EGJ. Partial expiration resulted in cessation of the flow across the EGJ, failure of esophageal peristalsis to traverse the entire length of the esophagus, increased esophageal transit time, and incomplete esophageal clearance of a liquid bolus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The effects of psychological stress on the esophagogastric junction pressure and swallow-induced relaxation.

BACKGROUND/AIMS: Short-term psychological stress increases pressure in the upper esophageal sphincter and increases esophageal contraction amplitude. The effects of short-term psychological stress on the two sphincteric mechanisms at the esophagogastric junction (EGJ), the lower esophageal sphincter (LES) and crural diaphragm, were studied. METHODS: Studies were performed in 20 normal, healthy subjects. LES and crural diaphragm functions were measured simultaneously using an electrode sleeve sensor. Three psychological stress tasks, math, cold, and stress interview, were tested. The data were analyzed for tonic (end expiratory) and phasic (inspiratory increase) EGJ pressure and electromyographic changes during the stress period. Spontaneous swallow-induced EGJ relaxation was also assessed. RESULTS: A significant decrease in tonic EGJ pressure occurred during the math and cold tasks. The tonic EGJ pressure was 19 +/- 2 and 14 +/- 2 during baseline and the math task, respectively. Stress caused no change in the phasic EGJ pressures. Tonic and phasic crural diaphragm electromyographic activity increased during all three stress periods. Spontaneous swallow-induced relaxation at the EGJ during the stress periods was reduced from 60% +/- 2% in the baseline to 39% +/- 5% during the stress periods. CONCLUSIONS: Short-term psychological stress lowers EGJ pressure through inhibition of the LES and increases tonic and phasic crural diaphragmatic contraction. Diminished swallow-induced relaxation at the EGJ during stress may lead to changes in esophageal contractions.

Adult↗
PubMed1993

Human sphincter of Oddi motility and cholecystokinin response following liver transplantation.

The reported incidence of sphincter of Oddi dysfunction following orthotopic liver transplantation has ranged from 3% to 7%. If sphincteric dysfunction is unrecognized, therapy may be inappropriate; when recognized, extensive surgery may be required. To prospectively identify patients with sphincteric dysfunction, we performed sphincter of Oddi motility studies through the t-tube tract three months after transplantation. Baseline sphincter motility and response to intravenous cholecystokinin were evaluated. The results of 10 subjects are reported; nine had normal basal sphincter pressure (16 +/- 5.8 mm Hg), and all had normal frequency (3.6 +/- 1/min), amplitude (86 +/- 31 mm Hg), and duration (4.5 +/- 1 sec) of phasic contractions. One subject had an elevated basal pressure (47 mm Hg). All, including the subject with elevated basal pressure, demonstrated a normal response to intravenous cholecystokinin with significant inhibition of phasic contraction frequency and amplitude. We demonstrate that simultaneous studies of the sphincter and duodenum can be obtained via the t-tube tract, providing the opportunity for prospective evaluation of sphincteric function. We conclude that sphincter of Oddi function usually remains normal following liver transplantation with choledochocholedochostomy.

Cholecystokinin↗