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.

Neutrophil kinetics and function after major trauma:A systematic review

BACKGROUND Immune dysfunction following major traumatic injury is complex and strongly associated with significant morbidity and mortality through the development of multiple organ dysfunction syndrome(MODS),persistent inflammation,immunosuppression,and catabolism syndrome and sepsis.Neutrophils are thought to be a pivotal mediator in the development of immune dysfunction.AIM To provide a review with a systematic approach of the recent literature describing neutrophil kinetics and functional changes after major trauma in humans and discuss hypotheses as to the mechanisms of the observed neutrophil dysfunction in this setting.METHODS Medline,Embase and PubMed were searched on January 15,2021.Papers were screened by two reviewers and those included had their reference list hand searched for additional papers of interest.Inclusion criteria were adults>18 years old,with an injury severity score>12 requiring admission to an intensive care unit.Papers that analysed major trauma patients as a subgroup were included.RESULTS Of 107 papers screened,48 were included in the review.Data were heterogeneous and most studies had a moderate to significant risk of bias owing to their observational nature and small sample sizes.Key findings included a persistently elevated neutrophil count,stereotyped alterations in cell-surface markers of activation,and the elaboration of heterogeneous and immunosuppressive populations of cells in the circulation.Some of these changes correlate with clinical outcomes such as MODS and secondary infection.Neutrophil phenotype remains a promising avenue for the development of predictive markers for immune dysfunction.CONCLUSION Understanding of neutrophil phenotypes after traumatic injury is expanding.A greater emphasis on incorporating functional and clinically significant markers,greater uniformity in study design and assessment of extravasated neutrophils may facilitate risk stratification in patients affected by major trauma.

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.

Management of critically ill patients with type 2 diabetes:The need for personalised therapy

Critical illness in patients with pre-existing diabetes frequently causes deterioration in glycaemic control.Despite the prevalence of diabetes in patients admitted to hospital and intensive care units,the ideal management of hyperglycaemia in these groups is uncertain.There are data that suggest that acute hyperglycaemia in critically ill patients without diabetes is associated with increased mortality and morbidity.Exogenous insulin to keep blood glucose concentrations < 10 mmol/L is accepted as standard of care in this group.However,preliminary data have recently been reported that suggest that chronic hyperglycaemia may result in conditioning,which protects these patients against damage mediated by acute hyperglycaemia.Furthermore,acute glucose-lowering to < 10 mmol/L in patients with diabetes with inadequate glycaemic control prior to their critical illness appears to have the capacity to cause harm.This review focuses on glycaemic control in critically ill patients with type 2 diabetes,the potential for harm from glucose-lowering and the rationale for personalised therapy.

Sleep during and following critical illness:A narrative review

Sleep is a complex process influenced by biological and environmental factors.Disturbances of sleep quantity and quality occur frequently in the critically ill and remain prevalent in survivors for at least 12 mo.Sleep disturbances are associated with adverse outcomes across multiple organ systems but are most strongly linked to delirium and cognitive impairment.This review will outline the predisposing and precipitating factors for sleep disturbance,categorised into patient,environmental and treatment-related factors.The objective and subjective methodologies used to quantify sleep during critical illness will be reviewed.While polysomnography remains the gold-standard,its use in the critical care setting still presents many barriers.Other methodologies are needed to better understand the pathophysiology,epidemiology and treatment of sleep disturbance in this population.Subjective outcome measures,including the Richards-Campbell Sleep Questionnaire,are still required for trials involving a greater number of patients and provide valuable insight into patients’experiences of disturbed sleep.Finally,sleep optimisation strategies are reviewed,including intervention bundles,ambient noise and light reduction,quiet time,and the use of ear plugs and eye masks.While drugs to improve sleep are frequently prescribed to patients in the ICU,evidence supporting their effectiveness is lacking.