Biomedical subjects

Nam Q Nguyen

Publications and source records attributed to Nam Q Nguyen.

10 recordsLinked to original sources

PubMed2007

Proximal gastric motility in critically ill patients with type 2 diabetes mellitus.

AIM: To investigate the proximal gastric motor response to duodenal nutrients in critically ill patients with long-standing type 2 diabetes mellitus. METHODS: Proximal gastric motility was assessed (using a barostat) in 10 critically ill patients with type 2 diabetes mellitus (59 +/- 3 years) during two 60-min duodenal infusions of Ensure (1 and 2 kcal/min), in random order, separated by 2 h fasting. Data were compared with 15 non-diabetic critically ill patients (48 +/- 5 years) and 10 healthy volunteers (28 +/- 3 years). RESULTS: Baseline proximal gastric volumes were similar between the three groups. In diabetic patients, proximal gastric relaxation during 1 kcal/min nutrient infusion was similar to non-diabetic patients and healthy controls. In contrast, relaxation during 2 kcal/min infusion was initially reduced in diabetic patients (P < 0.05) but increased to a level similar to healthy humans, unlike non-diabetic patients where relaxation was impaired throughout the infusion. Duodenal nutrient stimulation reduced the fundic wave frequency in a dose-dependent fashion in both the critically ill diabetic patients and healthy subjects, but not in critically ill patients without diabetes. Fundic wave frequency in diabetic patients and healthy subjects was greater than in non-diabetic patients. CONCLUSION: In patients with diabetes mellitus, proximal gastric motility is less disturbed than non-diabetic patients during critical illness, suggesting that these patients may not be at greater risk of delayed gastric emptying.

Adult↗

PubMed2007

Feed intolerance in critical illness is associated with increased basal and nutrient-stimulated plasma cholecystokinin concentrations.

OBJECTIVE: Delayed gastric emptying and intolerance to gastric feeding occur frequently in the critically ill. In these patients, gastric motor responses to nutrients are disturbed. Cholecystokinin (CCK) slows gastric emptying. The aim of this study was to determine plasma CCK concentrations during fasting and in response to small-intestine nutrient infusion in critically ill patients. DESIGN: Randomized, controlled trial. SETTING: Level 3, mixed medical and surgical intensive care unit. SUBJECTS: A total of 31 mechanically ventilated, critically ill patients (23 men, 51 +/- 3 yrs) and 28 healthy subjects (21 men, 43 +/- 2 yrs). INTERVENTIONS: Subjects received two 60-min duodenal infusions of Ensure (complete balanced nutrition), at 1 and 2 kcal/min, in a randomized, single-blind fashion. The nutrient infusions were separated by a 2-hr "washout" period. Blood samples for measurement of plasma CCK concentrations were obtained immediately before and every 20 mins during nutrient infusion. MEASUREMENTS AND MAIN RESULTS: Baseline and nutrient-stimulated plasma CCK concentrations were higher in critically ill patients compared with healthy subjects (p < .001). The magnitude of the rise in plasma CCK in response to nutrients was also greater in the critically ill (p < .01). Of the 23 patients who received enteral nutrition before the study, nine were intolerant of gastric feeding. In these patients, both the baseline plasma CCK concentration and the magnitude of CCK increase during nutrient infusions were greater than in patients with feed tolerance (p < .002). Impaired renal function was associated with an increased baseline CCK concentration but had no effect on the CCK response to nutrients. CONCLUSIONS: Both fasting and nutrient-stimulated plasma CCK concentrations are increased in critically ill patients, particularly in those with feed intolerance. This may provide a humoral mechanism for delayed gastric emptying seen in critical illness.

APACHE↗

PubMed2007

Erythromycin is more effective than metoclopramide in the treatment of feed intolerance in critical illness.

OBJECTIVE: This study aimed to a) compare the efficacy of metoclopramide and erythromycin in the treatment of feed intolerance in critical illness; and b) determine the effectiveness of "rescue" combination therapy in patients who fail monotherapy. DESIGN: Randomized controlled trial. SETTING: Level III mixed medical and surgical intensive care unit. PATIENTS: Ninety mechanically ventilated, medical patients with feed-intolerance (gastric residual volume>or=250 mL). INTERVENTIONS: Patients received either metoclopramide 10 mg intravenously four times daily (n=45) or erythromycin 200 mg intravenously twice a day (n=45) in a double-blind, randomized fashion. After the first dose, nasogastric feeding was commenced and 6-hourly nasogastric aspirates were performed. If a gastric residual volume>or=250 mL recurred on treatment, open-label, combination therapy was given. Patients were studied for 7 days. Successful feeding was defined as 6-hourly gastric residual volume<250 mL with a feeding rate>or=40 mL/hr. MEASUREMENTS AND MAIN RESULTS: Demographic data, blood glucose levels, and use of inotropes, opioids, and benzodiazepines were similar between the two groups. After 24 hrs of treatment, both monotherapies reduced the mean gastric residual volume (metoclopramide, 830+/-32 mL to 435+/-30 mL, p<.0001; erythromycin, 798+/-33 mL to 201+/-19 mL, p<.0001) and improved the proportion of patients with successful feeding (metoclopramide=62% and erythromycin=87%). Treatment with erythromycin was more effective than metoclopramide, but the effectiveness of both treatments declined rapidly over time. In patients who failed monotherapy, rescue combination therapy was highly effective (day 1=92%) and maintained its effectiveness for the study duration (day 6=67%). High pretreatment gastric residual volume was associated with poor response to prokinetic therapy. CONCLUSIONS: In critical illness, erythromycin is more effective than metoclopramide in treating feed intolerance, but the rapid decline in effectiveness renders both treatments suboptimal. Rescue combination therapy is highly effective, and further study is required to examine its role as the first-line therapy.

Critical Illness↗

PubMed2006

Relationship between pressure wave amplitude and esophageal bolus clearance assessed by combined manometry and multichannel intraluminal impedance measurement.

OBJECTIVES: Esophageal wave amplitude is an important determinant of esophageal clearance. A threshold of 30 mmHg is widely accepted as the threshold for effective clearance in the distal esophagus. However, the precise relationship between wave amplitude and clearance has received relatively little attention. The aim of this study was to assess the impact of peristaltic wave amplitude on esophageal volume clearance using multiple intraluminal impedance (MII) measurement. METHODS: Concurrent manometry and MII were performed on 42 healthy asymptomatic volunteers and 13 patients with ineffective esophageal motility. Esophageal motility was measured at four sites 5-cm apart, starting 2 cm above the lower esophageal sphincter. MII was measured at corresponding sites with electrodes incorporated into the manometric assembly. Ten 5-mL liquid (saline) boluses and ten 5-mL low impedance viscous boluses were tested in each subject. Pressure wave amplitude was determined at each site as well as peristaltic success of the responses. Bolus clearance was measured from individual recording segment and from the esophagus as a whole. RESULTS: The proportion of liquid boluses cleared at each site was directly related to wave amplitude and did not increase significantly above a threshold of 25 mmHg in the proximal esophagus, 22 mmHg in the mid-esophagus, and 30 mmHg in the distal esophagus. Corresponding wave amplitudes for total esophageal clearance were 35-40 mmHg. There was a good correlation between the wave amplitude at one site of the esophagus and those of the rest of the esophagus. For both liquid and viscous boluses, the likelihood of impaired clearance was directly related to the number of segments with hypotensive pressure waves. CONCLUSION: The findings confirm the validity of the wave amplitude threshold required for effective liquid bolus clearance and have established the amplitude threshold for clearance of viscous boluses. However, the number of hypotensive pressure waves required for the definition of ineffective motility may be too low.

Adolescent↗

PubMed2006

Long-standing type II diabetes mellitus is not a risk factor for slow gastric emptying in critically ill patients.

OBJECTIVE: Delayed gastric emptying (GE) is common both in critical illness and in patients with diabetes mellitus (DM). The effect of DM on the incidence of slow GE in these patients is unknown. We evaluated the effect of DM on liquid GE in critically ill patients. METHODS: Retrospective analysis of GE using a standard [13C]octanoic acid breath test in 12 type 2 DM patients compared with (a) 44 critically ill patients without DM, including (b) a subgroup of 15 age- and sex-matched patients and (c) 15 healthy volunteers. We determined the gastric emptying coefficient (GEC) and the gastric half-emptying time (t50). Mean APACHE II scores, blood glucose levels and use of morphine were similar between patient groups. RESULTS: GE was faster in critically ill patients with DM (t50 122 +/- 11 min, GEC: 3.8 +/- 0.3) than in patients without DM (t50 168 +/- 16 min, GEC 2.8 +/- 0.1) and in age- and sex-matched controls (t50 165 +/- 13 min, GEC 2.7 +/- 0.2) and was similar to that in healthy volunteers (t50 148 +/- 13 min, GEC 3.5 +/- 0.1). The proportion of patients with slow emptying (GEC < 3.2) was greater in non-DM (all = 56%, matched = 60%) than in DM patients (25%) and healthy subjects (26%). CONCLUSION: Long-standing type diabetes mellitus is not a risk factor for slow GE in critically ill patients.

APACHE↗

PubMed2006

Fasting and nutrient-stimulated plasma peptide-YY levels are elevated in critical illness and associated with feed intolerance: an observational, controlled study.

INTRODUCTION: Delayed gastric emptying and feed intolerance occur frequently in the critically ill. In these patients, gastric motor responses to nutrients are disturbed. Peptide YY (PYY) slows gastric emptying. The aim of this study was to determine fasting and nutrient-stimulated plasma PYY concentrations and their relationship to cholecystokinin (CCK) in critically ill patients. METHODS: Studies were performed in 19 unselected mechanically ventilated critically ill patients (12 males; 48 +/- 7 years old) in a randomised, single-blind fashion. Subjects received a 60-minute duodenal infusion of Ensure at either 1 or 2 kcal/minute. Blood samples were collected at baseline and at 20, 40, 60, and 180 minutes following commencement of the nutrient infusion for the measurement of plasma PYY and CCK concentrations (using radioimmunoassay). Patient data were compared to 24 healthy subjects (17 males; 43 +/- 2 years old). RESULTS: Fasting PYY concentration was higher in patients (P < 0.05), particularly in those with feed intolerance (P < 0.05). Plasma PYY concentrations were higher in patients during nutrient infusion (area under the curve [AUC] at 1 kcal/minute: 2,265 +/- 718 versus 1,125 +/- 138 pmol/l.min, P < 0.05; at 2 kcal/minute: 2,276 +/- 303 versus 1,378 +/- 210 pmol/l.min, P = 0.01) compared to healthy subjects. The magnitude of PYY elevation was greater in patients during the 1 kcal/minute infusion (AUC: 441 +/- 153 versus 186 +/- 58 pmol/l.min, P < 0.05), but not the 2 kcal/minute infusion. Fasting and nutrient-stimulated plasma CCK concentrations were higher in patients (P < 0.05). There was a relationship between plasma PYY and CCK concentrations during fasting (r = 0.52, P < 0.05) and nutrient infusion (r = 0.98, P < 0.0001). CONCLUSION: In critical illness, both fasting and nutrient-stimulated plasma PYY concentrations are elevated, particularly in patients with feed intolerance, in conjunction with increased CCK concentrations.

Adult↗

PubMed2005

Push enteroscopy alters management in a majority of patients with obscure gastrointestinal bleeding.

INTRODUCTION: Although enteroscopy has been increasingly used to investigate occult or obscure bleeding, little is known about its impact on patient management. The aim of the present paper was to evaluate both the diagnostic yield and the impact of push enteroscopy on the management of patients referred to a tertiary Australian institution. METHODS: Data were collected prospectively in all patients undergoing push enteroscopy at Royal Adelaide Hospital. Fifty-five patients were investigated for obscure gastrointestinal (GI) bleeding (25 women, mean age 65.6 years), the cause of which remained unknown despite previous gastroscopy and colonoscopy. The patients were divided into two groups: occult-obscure (anemia without macroscopic blood loss) and overt-obscure (macroscopic bleeding). Findings at enteroscopy, therapeutic procedures, and complications were recorded. Patients were followed to establish the impact of the procedure on subsequent management and clinical outcome. RESULTS: Enteroscopy demonstrated a potential site of bleeding in 38 patients (69%), and 38% of lesions found were within the reach of the gastroscope. The most common lesions were small intestinal angiodysplasia. Seventy-five percent of patients with positive findings had alterations to their management. After subsequent treatment, 62% were no longer anemic and there was a significant reduction in rebleeding (P < 0.05) and transfusion requirements (P < 0.05) compared to patients with negative findings. The procedure was well tolerated and complications were rare. CONCLUSION: Enteroscopy has a positive impact on patient management and clinical outcome in a majority of patients with obscure gastrointestinal bleeding.

Adult↗

PubMed2005

Multichannel intraluminal impedance monitoring in the evaluation of patients with non-obstructive Dysphagia.

BACKGROUND: Non-obstructive dysphagia (NOD) often poses diagnostic problems. The aim of this study was to evaluate the value of the addition of multichannel intraluminal impedance (MII) recording to esophageal manometry in the work-up of patients with NOD. METHODS: A total of 40 consecutive patients with NOD underwent combined esophageal MII recording and perfusion manometry. Ten liquid and 10 viscous boluses were tested in each patient. Values for bolus presence time (BPT) at each of the four recording sites and total bolus transit time (TBTT) were calculated. Bolus transit (BT) was considered to be normal when BPT at all sites and TBTT were within the normal limits defined in 42 healthy subjects. Patients were judged to have normal transit if >or=80% of liquid and >or=70% of viscous swallows showed normal transit. RESULTS: The following manometric diagnoses were made: normal motility (20), ineffective esophageal motility (IEM) (13), diffuse esophageal spasm (DES) (4), and achalasia (3). Abnormal transit for liquid and/or viscous boluses was found in 35.3% of patients with normal motility, in 66.7% of DES patients, and in 100% of achalasia patients. In patients with achalasia quantification of BT was often made impossible by low initial impedance baseline. Two IEM patients (15.4%) showed normal liquid and viscous transit. Swallows showing normal transit had significantly longer duration of LES relaxation in patients with normal manometry and IEM (p < 0.05). CONCLUSIONS: MII recording identifies esophageal function abnormalities in NOD patients with normal manometry, IEM, and DES. The MII technique seems to be less suitable for the most severe end of the dysphagia spectrum like achalasia.

Adult↗

PubMed2005

Recent developments in esophageal motor disorders.

PURPOSE OF REVIEW: Over the past year, further insights into the control of esophageal motility and disturbances associated with motor disorders, and additional information about the treatment of esophageal motor disorders has emerged. This review outlines the major developments in these areas. RECENT FINDINGS: The pharyngeal and esophageal phases of swallowing appear to be controlled by different areas within the vagal nuclei. Differences in the density and activation of calcium channels may explain differences in activity between the circular and clasp fibers of the lower esophageal sphincter and in the peristaltic function of the esophageal body. Tonic cholinergic input is the major determinant of esophageal tone. Experimental diabetes mellitus alters the mechanics of the esophageal body. Subtle abnormalities of peristalsis have been identified by high-resolution manometry and 24-hour ambulatory manometry that are not evident on standard manometry in patients with non-obstructive dysphagia. In achalasia, additional support has been provided for vagal damage in some patients with achalasia as well as evidence for a viral-induced immune damage to the myenteric plexus. The three main treatments for achalasia - botulinum toxin, pneumatic dilatation, and minimally invasive myotomy have been re-evaluated. Myotomy continues to provide the best results. Intraoperative manometry would seem to be a useful aid to minimize the risk of incomplete myotomy. The usefulness of glucagon in relieving food bolus obstruction has been revisited in a retrospective study. SUMMARY: These studies provide further information with which to more effectively manage esophageal motor disorders.

Animals↗

PubMed2003

Gastroesophageal reflux disease.

Globally, gastroesophageal reflux disease (GERD) remains a common and important clinical disorder. This review summarizes the major advances in the understanding and treatment of GERD that have been made in the past 12 months. Epidemiologic studies have yielded additional data on the clinical presentation and natural history of GERD in the East. Further insights have been presented on the pathogenesis of GERD, including the immunoregulatory environment of GERD, the neurophysiology of transient lower esophageal sphincter relaxation (TLESR), the mechanics of the esophagogastric junction as well as the influence of Helicobacter pylori. Diagnostically, a new acid exposure sensor may be a helpful cost-effective tool. Developments have been made in pharmacotherapy for TLESR. There is ongoing interest in endoscopic therapy and further developments have been made in laparoscopic fundoplication. The cost-effectiveness of several management strategies has been evaluated, aiming to reduce the cost impact of GERD on the health care system.

Journal Article↗