Edgard Ferro Collares

Gastric emptying in premature newborns with acute respiratory distress

Objectives: The authors hypothesized that acute respiratory distress (ARD) delays gastric emptying. The objective was to test this hypothesis by assessing gastric emptying on the second and seventh days of life in premature infants with ARD resulting from pulmonary disease. Methods: Thirty-nine newborns with ARD starting on the first day of life were selected and paired with 39 healthy control newborns matched by weight (within 250 g). Gestational age was ≤35 weeks and birth weight was ≤1750 g for all subjects. Gastric emptying was assessed at 48.0 ± 24.0 hours and at 168.0 ± 24.0 hours of life. A test meal consisting of 3 mL/kg of 5% glucose in water labeled with phenol red was administered by gastric tube over 1 minute and gastric retention was determined as percent test meal remaining in the stomach 30 minutes after administration. Results: Gastric retention at 30 minutes varied considerably in both groups and was significantly higher (P < 0.01) in newborns with ARD (61.4%) than controls (51.8%) at 48.0 ± 24.0 hours, decreasing significantly after partial or full remission of ARD at 168 ± 24 hours of life. Gastric retention was 60.2% in newborns with feeding intolerance and 36.8% in tolerant newborns (P < 0.001) at 168 hours. ARD and periventricular or intraventricular hemorrhage were predictors of gastric retention at 48 ± 24 hours of life, whereas feeding intolerance and gestational age were predictors of gastric retention at 168 ± 24 hours. Gastric retention was inversely correlated with gestational age. Conclusion: Gastric emptying is delayed in premature infants with ARD during the first 72 hours of life and may impair the initiation of enteral feeding.

Effect of fundoplication on the gastric emptying of liquids

To evaluate the effect of fundoplication on the gastric emptying (GE) of liquids, the authors studied 96 male Wistar rats divided into three main groups: group E (early postoperative), formed by 32 rats that received physiological saline as a test meal and whose gastric emptying was evaluated 8 days after surgery; group L (late postoperative), which received the same test meal but was evaluated 29 days after surgery; and group G (glucose), which received 5% glucose in water and was studied 8 days after surgery. Each group was subdivided in two subgroups of 16 animals: in one (atropine), the animals received intravenous (I.V.) atropine sulfate (0.3 mg/100 mg rat weight) 60 minutes before GE test; the other subgroup (controls) received I.V. physiological saline. In both subgroups 8 animals had been submitted to fundoplication and 8 to sham operation. Every test meal, containing 6 mg% red phenol, was infused by gravity through a metallic catheter. Gastric retention was determined by measuring the concentration of the marker in the liquid recovered from the stomach 10 minutes after infusion. In the animals of group E, fundoplication increased the gastric emptying of physiological saline, both in the control and the atropine subgroups. In the L group, gastric retention values were similar in fundoplication and sham-operated rats, suggesting an adaptation of the stomach to the fundoplication. In the G group, fundoplication enhanced GE among the control animals, but not among those receiving I.V. atropine sulfate. These results support the importance of gastric emptying studies in every patient to be submitted to fundoplication.

Effect of baclofen on liquid and solid gastric emptying in rats

CONTEXT Gamma-aminobutyric acid (GABA) is a potent inhibitory neurotransmitter. There is evidence that GABA(B) receptors located in the dorsal complex and in afferent fibers of the vagus nerve participate in the control of gastrointestinal motility. OBJECTIVE To assess the intracerebroventricularly (ICV) and intravenously (IV) effect of baclofen, a GABA(B) receptor agonist, on liquid and solid gastric emptying in rats. METHODS Adult male Wistar rats weighing 250-300 g (n = 6-8 animals) were used. Gastric emptying of liquid test meals labeled with phenol red was evaluated by the determination of percent gastric retention (%GR) 10 and 15 min after orogastric administration of saline and 10% glucose meals, respectively. Baclofen was injected ICV (1 and 2 µg/animal) through a tube implanted into the lateral ventricle of the brain and was injected IV (1 and 2 mg/kg) into a tail vein. The gastric emptying of liquid was determined 10 or 30 min after ICV and IV baclofen administration, respectively. The gastric emptying of the solid meal was assessed by the determination of percent gastric retention 2 h after the beginning of the ingestion of the habitual ratio by the animal, consumed over a period of 30 min. Baclofen was administered ICV (1 and 2 µg/animal) or IV (1 and 2 mg/kg) immediately after the end of the ingestion of the solid meal. The control groups received vehicle (sterile saline solution) ICV or IV. RESULTS The group of animals receiving baclofen ICV (2 mg/animal) presented a significantly lower (P<0.05, Tukey test) %GR (mean ± SEM) of the saline (18.1 ± 2.5%) compared to control (33.2 ± 2.2%). In the group receiving the drug IV, the gastric retention of the same test meal did not differ from control. ICV and IV administration of baclofen had no effect on the gastric emptying of the 10% glucose solution compared to control. ICV administration of 1 or 2 mg baclofen/animal significantly increased the gastric retention of the solid test meal (57.9 ± 6.5% and 66.6 ± 6.3%, respectively) compared to control (35.1 ± 4.4%). The same phenomenon was observed only with the IV dose of 2 mg/kg (71.9 ± 2.6%) compared to control (52.7 ± 2.8%). CONCLUSION Baclofen administered: 1. ICV (2 µg/animal), but not IV, increased gastric emptying of a non-caloric isotonic liquid test meal (saline); 2. when administered ICV or IV, it had no effect of gastric emptying of a 10% glucose solution; 3) when administered ICV (1 and 2 mg/animal) and IV (2 mg/kg) it delayed the gastric emptying of the solid meal.

Prolonged esophageal pH monitoring in the diagnosis of pathologic reflux in neonates

OBJECTIVES: To present indications and results of prolonged esophageal pH monitoring in diagnosing pathologic gastroesophageal reflux in newborns during their stay in the neonatal unit. METHODS: This retrospective descriptive-analytical study of 85 prolonged esophageal pH monitoring in neonates was performed, between October 1995 and March 1998, in a tertiary intensive care unity. A Digitrapper MKIII device, pH probes with one or two channels, and antimony electrodes were utilized. The probe was placed 3 cm above the gastroesophageal junction. RESULTS: The main indications of this esophageal pH study were hypoxemia episodes demanding supplemental oxygen, and caffeine resistant apnea. The means -/+ SD of birth-weight and gestational age in the patients evaluated were, respectively, 1,204-/+460 g and 30.5 -/+ 2.9 weeks. There was no statistical difference observed in newborns with and without pathologic gastroesophageal reflux according to clinical manifestations and monitoring conditions. Forty-eight newborns (56.4%) presented 17.6-/+9.1% of the whole examination time with a pH below 4. Of these patients, 31.1% presented birth-weight below 1,000 g. Duodenogastroesophagic was diagnosed in two cases. Of the studied premature with chronic lung disease, 66.7% presented pathologic reflux. CONCLUSION: Prolonged pH esophageal monitoring is helpful in the differential diagnosis of the unspecific and very frequent clinic manifestations in very low birth-weight infants.

THE ONTOGENY OF SALIVA SECRETION IN INFANTS AND ESOPHAGOPROTECTION

BACKGROUND Several studies have reported that severe reflux esophagitis is rare in infants despite the well known high occurrence of regurgitation in early infancy. There is evidence of the importance of saliva for the pre-epithelial protection of the esophageal mucosa. RESULTS A longitudinal study conducted on healthy infants indicated that the stimulated capacity of saliva secretion (saliva output per kg of body weight) was significantly higher during their first year of age compared to older children and adults. In addition, this secretion pattern was also observed in low weight newborns during the first weeks of life and persisted in infants with severe protein-calorie malnutrition (marasmus). CONCLUSION The greater ability to secrete saliva is an important physiological condition that may protect the infant from acid/pepsin aggression to the esophagus during early stages of development.

Neural Mechanisms and Delayed Gastric Emptying of Liquid Induced Through Acute Myocardial Infarction in Rats

Background In pathological situations, such as acute myocardial infarction, disorders of motility of the proximal gut can trigger symptoms like nausea and vomiting. Acute myocardial infarction delays gastric emptying (GE) of liquid in rats. Objective Investigate the involvement of the vagus nerve, α 1-adrenoceptors, central nervous system GABAB receptors and also participation of paraventricular nucleus (PVN) of the hypothalamus in GE and gastric compliance (GC) in infarcted rats. Methods Wistar rats, N = 8-15 in each group, were divided as INF group and sham (SH) group and subdivided. The infarction was performed through ligation of the left anterior descending coronary artery. GC was estimated with pressure-volume curves. Vagotomy was performed by sectioning the dorsal and ventral branches. To verify the action of GABAB receptors, baclofen was injected via icv (intracerebroventricular). Intravenous prazosin was used to produce chemical sympathectomy. The lesion in the PVN of the hypothalamus was performed using a 1mA/10s electrical current and GE was determined by measuring the percentage of gastric retention (% GR) of a saline meal. Results No significant differences were observed regarding GC between groups; vagotomy significantly reduced % GR in INF group; icv treatment with baclofen significantly reduced %GR. GABAB receptors were not conclusively involved in delaying GE; intravenous treatment with prazosin significantly reduced GR% in INF group. PVN lesion abolished the effect of myocardial infarction on GE. Conclusion Gastric emptying of liquids induced through acute myocardial infarction in rats showed the involvement of the vagus nerve, alpha1- adrenergic receptors and PVN.

Effect of an isolated mild to moderate ischemic brain injury in the gastric emptying of liquids in rats

PURPOSE To evaluate the effect of hypoxic-ischemic brain injury over the gastric emptying of liquids in rats. METHODS Fifty-two Wistar rats aged six weeks and weighing between 100 g and 150 g were divided in three groups. A Control group (C), a Sham group (S) undergoing sham procedure, and a Hypoxic-ischemic group (HI) consisting of 18 animals undergoing surgical ligature of the left carotid artery and exposure to hypoxic environment for three hours. Half of the animals were studied in the third day post-HI procedure (Early) and nine in the 14th day post-HI procedure (Late). Gastric emptying was evaluated by an infusion technique using fenolsulftalein as a marker. RESULTS After the HI procedure, all animals displayed left eyelid ptosis, and six animals showed minor sideway gait. Histological examination confirmed de brain injury in all animals from the HI group. There was no statistical significant difference among the mean gastric retention values of the three groups neither in the Early nor in the Late evaluation. CONCLUSION Isolated HI brain injury was not associated with delayed gastric emptying.

Efeito do lipopolissacarídio bacteriano sobre o esvaziamento gástrico de ratos: avaliação do pré-tratamento com dexametasona e azul de metileno

ABSTRACT – Background – The nitric oxide might be a putative mediator of the decrease in gastric emptying induced by bacterial lipopolysaccharidein rats. Aim – For that, we evaluated the effect of the pretreatment intravenous with dexamethasone and methylene blue in the retardationprocess of gastric emptying induced by intravenous application of lipopolysaccharide in rats. Dexamethasone has been shown to inhibit theinduction of NOS II (induced NO-synthase) while the methylene blue, that blocks the soluble guanylyl cyclase, inhibits nitric oxide synthasesand, in addition, inactivates nitric oxide directly. Material and Methods – Male Wistar rats, specific patogenic free, were used after a 24 hourfast and 1 hour-water withdrawn. The pretreatment was performed using dexamethasone solutions (3 and 6 mg/kg), methylene blue (2 mg/kg)or sterile vehicle. The treatment consisted in the application of lipopolysaccharide (50 µg/kg) or vehicle. The time period between thepretreatment and treatment was 10 minutes, excluding the study with dexamethasone 6 mg/kg that was 1 hour. The gastric emptying wasevaluated 1 hour after the lipopolysaccharide application, except for two studies with dexamethasone 3 mg/kg in which the time periods were2 and 8 hours. A saline solution containing phenol red was used as the test meal. The gastric emptying was determined by measuring gastricretention 10 minutes after the orogastric infusion of the test meal.

Efeito do lipopolissacarídio bacteriano sobre o esvaziamento gástrico de ratos: avaliação do pré-tratamento com Nw-nitro-L-arginine methyl ester (L-NAME)

BACKGROUND There is evidence that nitric oxide plays a role in the decrease in gastric emptying induced by bacterial lipopolysaccharide. AIM To evaluate the effect of pretreatment with Nw-nitro-L-arginine methyl to ester, one competitive inhibitor of the nitric oxide synthases, on the gastric emptying delay induced by lipopolysaccharide. MATERIAL AND METHODS Male Wistar rats, SPF, were used after 24 h fast and 1 h-water withdrawn. The pretreatment was done intravenously with vehicle (saline) or N(w)-nitro-L-arginine methyl to ester in the doses of 0.5, 1, 2.5 e 5 mg/kg. After 10 min, the animals were treated iv with lipopolysaccharide (50 microg/kg) or received vehicle (saline). The gastric emptying was evaluated 1 h after the lipopolysaccharide administration. A saline solution containing phenol red was used as the test meal. The gastric emptying was indirectly assessed by the determination of percent gastric retention of the test meal 10 min after orogastric administration. RESULTS The animals pretreated with vehicle and treatment with lipopolysaccharide have significant rise of the gastric retention (average = 57%) in comparison with the controls receiving only vehicle (38.1%). The pretreatment with the different doses of N(w)-nitro-L-arginine methyl to ester did not modify per se the gastric retention in comparison with the animals pretreated with vehicle. Pretreatment with N(w)-nitro-L-arginine methyl to ester with the dose of 1 mg/kg determined a discrete but significant reduction in the gastric retention (52%) of animals treated with lipopolysaccharide in comparison with vehicle-pretreated rats. Paradoxically, animals pretreated with 2.5 or 5 mg of N(w)-nitro-L-arginine methyl to ester/kg followed by treatment with lipopolysaccharide displayed a significantly higher gastric retention (74.7% and 80.5%, respectively) as compared to their controls, pretreated with the same doses of the inhibitor and treated with vehicle (40.5% and 38.7%, respectively) and to those pretreated with vehicle and treated with the same toxin. CONCLUSION The pretreatment with N(w)-nitro-L-arginine methyl to ester at low dose (1 mg/kg) resulted in a discrete inhibition of the gastric emptying delay induced by lipopolysaccharide. Nevertheless, N(w)-nitro-L-arginine methyl to ester at higher doses (2.5 and 5 mg/kg) induced an enhancement of the lipopolysaccharide effect on gastric emptying, despite not interfering with the gastric emptying per se.