Inter-relationships between gastric emptying and glycaemia:Implications for clinical practice

Gastric emptying(GE)exhibits a wide inter-individual variation and is a major determinant of postprandial glycaemia in health and diabetes;the rise in blood glucose following oral carbohydrate is greater when GE is relatively more rapid and more sustained when glucose tolerance is impaired.Conversely,GE is influenced by the acute glycaemic environment acute hyperglycaemia slows,while acute hypoglycaemia accelerates it.Delayed GE(gastroparesis)occurs frequently in diabetes and critical illness.In diabetes,this poses challenges for management,particularly in hospitalised individuals and/or those using insulin.In critical illness it compromises the delivery of nutrition and increases the risk of regurgitation and aspiration with consequent lung dysfunction and ventilator dependence.Substantial advances in knowledge relating to GE,which is now recognised as a major determinant of the magnitude of the rise in blood glucose after a meal in both health and diabetes and,the impact of acute glycaemic environment on the rate of GE have been made and the use of gut-based therapies such as glucagon-like peptide-1 receptor agonists,which may profoundly impact GE,in the management of type 2 diabetes,has become commonplace.This necessitates an increased understanding of the complex inter-relationships of GE with glycaemia,its implications in hospitalised patients and the relevance of dysglycaemia and its management,particularly in critical illness.Current approaches to management of gastroparesis to achieve more personalised diabetes care,relevant to clinical practice,is detailed.Further studies focusing on the interactions of medications affecting GE and the glycaemic environment in hospitalised patients,are required.

Nutrient stimulation of mesenteric blood flow-implications for older critically ill patients

Nutrient ingestion induces a substantial increase in mesenteric blood flow. In older persons(aged ≥ 65 years), particularly those with chronic medical conditions, the cardiovascular compensatory response may be inadequate to maintain systemic blood pressure during mesenteric blood pooling, leading to postprandial hypotension. In older ambulatory persons, postprandial hypotension is an important pathophysiological condition associated with an increased propensity for syncope, falls, coronary vascular events, stroke and death. In older critically ill patients, the administration of enteral nutrition acutely increases mesenteric blood flow, but whether this pathophysiological response is protective, or precipitates mesenteric ischaemia, is unknown. There are an increasing number of older patients surviving admission to intensive care units, who are likely to be at increased risk of postprandial hypotension, both during, and after, their stay in hospital. In this review, we describe the prevalence, impact and mechanisms of postprandial hypotension in older people and provide an overview of the impact of postprandial hypotension on feeding prescriptions in older critically ill patients. Finally, we provide evidence that postprandial hypotension is likely to be an unrecognised problem in older survivors of critical illness and discuss potential options for management.