Objectives To determine whether preoperative optimisation of oxygen delivery improves outcome after major elective surgery, and to determine whether the inotropes, adrenaline and dopexamine, used to enhance oxygen delivery influence outcome. Design Randomised controlled trial with double blinding between inotrope groups. Setting York District Hospital, England. Subjects 138 patients undergoing major elective surgery who were at risk of developing postoperative complications either because of the surgery or the presence of coexistent medical conditions. Interventions Patients were randomised into three groups. Two groups received invasive haemodynamic monitoring, fluid, and either adrenaline or dopexamine to increase oxygen delivery. Inotropic support was continued during surgery and for at least 12 hours afterwards. The third group (control) received routine perioperative care. Main outcome measures Hospital mortality and morbidity. Results Overall, 3/92 (3%) preoptimised patients died compared with 8/46 controls (17%) (P = 0.007). There were no differences in mortality between the treatment groups, but 14/46 (30%) patients in the dopexamine group developed complications compared with 24/46 (52%) patients in the adrenaline group (difference 22%, 95% confidence interval 2% to 41%) and 28 patients (61%) in the control group (31%, 11% to 50%). The use of dopexamine was associated with a decreased length of stay in hospital. Conclusion Routine preoperative optimisation of patients undergoing major elective surgery would be a significant and cost effective improvement in perioperative care.

Excessive stress in our daily lives is known to be a key determinant of economic, health and social outcomes. The impact of stress on cognitive abilities, such as memory, is well documented in animal studies but it is not yet clear how stress in human social interactions affects memory. This review systematically explored the evidence regarding the effects of psychosocial stress on memory and its associated cognitive abilities. To do this, we searched PubMed, PsycInfo and Web of Science databases for studies of psychosocial stress that also assessed long-term memory or related cognitive functions, such as working memory or attention. Fifty-one papers assessing the effects of psychosocial stress on memory were identified and compared based on the timing of stress induction. No overall effect of psychosocial stress induction was seen on long-term or working memory regardless of whether stress induction occurred following encoding or before retrieval. Psychosocial stress had a moderate differential effect when emotional vs. neutral stimuli were used, but the direction of the effect varied across studies. Psychosocial stress decreased performance on executive function tasks. Our findings demonstrate that, in humans, psychosocial stress may not have the clear effects on memory previously ascribed to it, highlighting differences with previous reviews on mainly physiological stress. We offer some perspectives for future research and identify gaps in the literature, including the need for adequate control groups, the impact of inter-individual differences in responsivity to stressors, and a need to improve our understanding of the mechanisms through which psychosocial stress impacts upon cognition.

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Physical stress, such as from the cold‐pressor test, has been robustly associated with altered memory retrieval, but it is less clear whether the same happens following psychosocial stress. Studies using psychosocial stressors report mixed effects on memory, leading to uncertainty about the common cognitive impact of both forms of stress. The current study uses a series of four carefully designed experiments, each differing by only a single critical factor to determine the effects of psychosocial stress on specific aspects of episodic memory. In three experiments, we induced psychosocial stress after participants encoded words, then assessed retrieval of those words after a prolonged delay. These experiments found no effect of post‐encoding stress on recognition of neutral words or cued recall of word‐pairs, but a small effect on recollection of semantically related words. There were, however, positive relationships within the stress group between measures of stress (cortisol in experiment 1 and self‐reported‐anxiety in experiment 3) and recollection of single word stimuli. In the fourth experiment, we found that psychosocial stress immediately before retrieval did not influence word recognition. Recollection, particularly for semantically related stimuli, may therefore be more susceptible to the effects of psychosocial stress, and future studies can assess how this relates to other forms of stress. Overall, our findings suggest that the effects of psychosocial stress on episodic memory may be more subtle than expected, warranting further exploration in larger studies.

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