Age-related impairment of esophagogastric junction relaxation and bolus flow time

AIM To investigate the functional effects of abnormal esophagogastric(EGJ) measurements in asymptomatic healthy volunteers over eighty years of age. METHODS Data from 30 young controls(11 M, mean age 37 ± 11 years) and 15 aged subjects(9 M, 85 ± 4 years) were compared for novel metrics of EGJ-function: EGJcontractile integral(EGJ-CI), "total" EGJ-CI and bolus flow time(BFT). Data were acquired using a 3.2 mm, 25 pressure(1 cm spacing) and 12 impedance segment(2 cm) solid-state catheter(Unisensor and MMS SolarGI system) across the EGJ. Five swallows each of 5 m L liquid(L) and viscous(V) bolus were analyzed. Mean values were compared using Student's t test for normally distributed data or Mann Whitney U-test when non-normally distributed. A P value < 0.05 was considered significant.RESULTS EGJ-CI at rest was similar for older subjects compared to controls. "Total" EGJ-CI, measured during liquid swallowing, was increased in older individuals when compared to young controls(O 39 ± 7 mm Hg.cm vs C 18 ± 3 mm Hg.cm; P = 0.006). For both liquid and viscous bolus consistencies, IRP4 was increased(L: 11.9 ± 2.3 mm Hg vs 5.9 ± 1.0 mm Hg, P = 0.019 and V: 14.3 ± 2.4 mm Hg vs 7.3 ± 0.8 mm Hg; P = 0.02) and BFT was reduced(L: 1.7 ± 0.3 s vs 3.8 ± 0.2 s and V: 1.9 ± 0.3 s vs 3.8 ± 0.2 s; P < 0.001 for both) in older subjects, when compared to young. A matrix of bolus flow and presence above the EGJ indicated reductions in bolus flow at the EGJ occurred due to both impaired bolus transport through the esophageal body(i.e., the bolus never reached the EGJ) and increased flow resistance at the EGJ(i.e., the bolus retained just above the EGJ).CONCLUSION Bolus flow through the EGJ is reduced in asymptomatic older individuals. Both ineffective esophageal bolus transport and increased EGJ resistance contribute to impaired bolus flow.

Mechanisms underlying feed intolerance in the critically ill: Implications for treatment

Malnutrition is associated with poor outcomes in critically ill patients. Although nutritional support is yet to be proven to improve mortality in non-malnourished critically ill patients, early enteral feeding is considered best practice. However, enteral feeding is often limited by delayed gastric emptying. The best method to clinically identify delayed gastric emptying and feed intolerance is unclear. Gastric residual volume (GRV) measured at the bedside is widely used as a surrogate marker for gastric emptying, but the value of GRV measurement has recently been disputed. While the mechanisms underlying delayed gastric emptying require further investigation, recent research has given a better appreciation of the pathophysiology. A number of pharmacological strategies are available to improve the success of feeding. Recent data suggest a combination of intravenous metoclopramide and erythromycin to be the most successful treatment, but novel drug therapies should be explored. Simpler methods to access the duodenum and more distal small bowel for feed delivery are also under investigation. This review summarises current understanding of the factors responsible for, and mechanisms underlying feed intolerance in critical illness, together with the evidence for current practices. Areas requiring further research are also highlighted.

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.

Lower esophageal sphincter relaxation is impaired in older patients with dysphagia

AIM: To characterize the effects of age on the mechanisms underlying the common condition of esophageal dysphagia in older patients, using detailed manometric analysis. METHODS: A retrospective case-control audit was performed on 19 patients aged ≥ 80 years (mean age 85 ± 0.7 year) who underwent a manometric study for dysphagia (2004-2009). Data were compared with 19 younger dysphagic patients (32 ± 1.7 years). Detailed manometric analysis performed prospectively included basal lower esophageal sphincter pressure (BLESP), pre-swallow and nadir LESP, esophageal body pressures and peristaltic duration, during water swallows (5 mL) in right lateral (RL) and upright (UR) postures and with solids. Data are mean ± SE; a P-value < 0.05 was considered significant. RESULTS: Elderly dysphagic patients had higher BLESP than younger patients (23.4 ± 3.8 vs 14.9 ± 1.2 mmHg; P < 0.05). Pre-swallow LESP was elevated in the elderly in both postures (RL: 1 and 4 s P = 0.019 and P = 0.05; UR: P < 0.05 and P = 0.05) and solids (P < 0.01). In older patients, LES nadir pressure was higher with liquids (RL: 2.3 ± 0.6 mmHg vs 0.7 ± 0.6 mmHg, P < 0.05; UR: 3.5 ± 0.9 mmHg vs 1.6 ± 0.5 mmHg, P = 0.01) with shorter relaxation after solids (7.9 ± 1.5 s vs 9.7 ± 0.4 s, P = 0.05). No age-related differences were seen in esophageal body pressures or peristalsis duration. CONCLUSION: Basal LES pressure is elevated and swallow-induced relaxation impaired in elderly dysphagic patients. Its contribution to dysphagia and the effects of healthy ageing require further investigation.

Modulation of individual components of gastric motor response to duodenal glucose

AIM:To evaluate individual components of the antro-pyloro-duodenal(APD)motor response to graded small intestinal glucose infusions in healthy humans.METHODS:APD manometry was performed in 15healthy subjects(12 male;40±5 years,body mass index 26.5±1.6 kg/m2)during four 20-min intraduodenal infusions of glucose at 0,0.5,1.0 and 1.5 kcal/min,in a randomised double-blinded fashion.Glucose solutions were infused at a rate of 1 mL/min and separated by 40-min"wash-out"period.Data are mean±SE.Inferential analyses are repeated measure analysis of variance with Bonferroni post-hoc testing.RESULTS:At 0 kcal/min frequency of pressure waves were:antrum(7.5±1.8 waves/20 min)and isolated pyloric pressure waves(IPPWs)(8.0±2.3 waves/20min)with pyloric tone(0.0±0.9 mmHg).Intraduodenal glucose infusion acutely increased IPPW frequency(P<0.001)and pyloric tone(P=0.015),and decreased antral wave frequency(P=0.007)in a dosedependent fashion.A threshold for stimulation was observed at 1.0 kcal/min for pyloric phasic pressure waves(P=0.002)and 1.5 kcal/min for pyloric tone and antral contractility.CONCLUSION:There is hierarchy for the activation of gastrointestinal motor responses to duodenal glucose infusion.An increase in IPPWs is the first response observed.

Impact of bolus volume on small intestinal intra-luminal impedance in healthy subjects

AIM: To assess the impact of bolus volume on the characteristics of small intestinal (SI) impedance signals.METHODS: Concurrent SI manometry-impedance measurements were performed on 12 healthy volunteers to assess the pattern of proximal jejunal fluid bolus movement over a 14 cm-segment.Each subject was given 34 boluses of normal saline (volume from 1 to 30 mL) via the feeding tube placed immediately above the proximal margin of the studied segment.A bolus-induced impedance event occurred if there was > 12% impedance drop from baseline,over ≥ 3 consecutive segments within 10 s of bolus injection.A minor or major imped-ance event was defined as a duration of impedance drop < 60 s or ≥ 60 s,respectively.RESULTS: The minimum volume required for a detectable SI impedance event was 2 mL.A direct linear relationship between the SI bolus volume and the occurrence of impedance events was noted until SI bolus volume reached 10 mL,a volume which always produced an impedance flow event.There was a moderate correlation between the bolus volume and the duration of impedance drop (r = 0.63,P < 0.0001) and the number of propagated channels (r = 0.50,P < 0.0001).High volume boluses were associated with more major impedance events (≥ 10 mL boluses = 63%,3 mL boluses = 17%,and < 3 mL boluses = 0%,P = 0.02).CONCLUSION: Bolus volume had an impact on the type and length of propagation of SI impedance events and a threshold of 2 mL is required to produce an event.