Motility patterns of ex vivo intestine segments depend on perfusion mode

AIM:To evaluate and characterize motility patterns from small intestinal gut segments depending on different perfusion media and pressures.METHODS:Experiments were carried out in a custom designed perfusion chamber system to validate and standardise the perfusion technique used.The perfusion chamber was built with a transparent front wall allowing for optical motility recordings and a custom made fastener to hold the intestinal segments.Experiments with different perfusion and storage media combined with different luminal pressures were carried out to evaluate the effects on rat small intestine motility.Software tools which enable thevisualization and characterization of intestinal motility in response to different stimuli were used to evaluate the videotaped experiments.The data collected was presented in so called heatmaps thus providing a concise overview of form and strength of contractility patterns.Furthermore,the effect of different storage media on tissue quality was evaluated.HaematoxylinEosin stainings were used to compare tissue quality depending on storage and perfusion mode.RESULTS:Intestinal motility is characterized by different repetitive motility patterns,depending on the actual situation of the gut.Different motility patterns could be recorded and characterized depending on the perfusion pressure and media used.We were able to describe at least three different repetitive patterns of intestinal motility in vitro.Patterns with an oral,anal and oro-anal propagation direction could be recorded.Each type of pattern finalized its movement with or without a subsequent distension of the wavefront.Motility patterns could clearly be distinguished in heatmap diagrams.Furthermore undirected motility could be observed.The quantity of the different patterns varies and is highly dependent on the perfusion medium used.Tissue preservation varies depending on the perfusion medium utilized,therefore media with a simple composition as Tyrode solution can only be recommended for short time experiments.The more complex media,MEM-HEPES medium and especially AQIXRS-I tissue preservation reagent preserved the tissue much better during perfusion.CONCLUSION:Perfusion media have to be carefully chosen considering type and duration of the experiments.If excellent tissue quality is required,complex media are favorable.Perfusion pressure is also of great importance due to the fact that a minimum amount of luminal pressure seems to be necessary to trigger intestinal contractions.

Preoperative nuclear stress testing in the very old patient population

BACKGROUND Elderly patients awaiting moderate to high-risk surgery may undergo nuclear stress testing(NST)in order to evaluate their cardiovascular risk.The prognostic utility of such testing in the very elderly(≥85 years)has yet to be fully evaluated.Octogenarians and nonogenarians frequently have a number of concurrent conditions including a high rate of coronary disease,and therefore the prognostic value of NST for their preoperative risk assessment has been questioned.Our evaluation assesses the ability of nuclear stress testing to predict peri-operative cardiac outcomes in this patient population.AIM To investigate the ability of NST to predict peri-operative cardiac outcomes in elderly patients awaiting moderate to high-risk surgery.METHODS Patients≥85 years undergoing pre-operative NST were retrospectively evaluated.Patients undergoing low-risk surgery were excluded.Major adverse cardiac events(MACE)were considered any adverse event that occurred prior to discharge and included acute heart failure,arrhythmia,acute myocardial infarction,unstable angina,or death.Associations between patient risk factors,MACE,and the obtained results of the pre-operative stress testing,ejection fraction(<40%or≥40%),summed stress score(≤8,≥9),and the summed difference score(≤0,>0)were analyzed.RESULTS A total of 69 patients(mean age 88±2.6 years,31 males)underwent nuclear stress testing prior to surgery.There were 41(60%)patients found to have an abnormal NST.Sixteen(23%)patients were noted to experience post-operative MACE.No significant associations between risk factors and MACE were noted.Patients with an abnormal NST and/or a summed stress score≥9 weresignificantly(P<0.01)more likely to develop peri-operative MACE.CONCLUSION Indicated preoperative NST is useful to assess pre-operative risk in elderly patients≥85 years undergoing moderate to high-risk surgery.