Causes of cancellations on the day of surgery at two major university hospitals.

Cancellations of elective cases on the day of surgery waste valuable operating-room time. The authors studied cancellations at an American hospital and a Norwegian university hospital to test (a) whether the quality of hospital administrative data on cancellations is sufficient for meaningful comparative analysis and (b) whether causes of cancellations at these 2 major academic hospitals are comparable. Large retrospective cause-of-cancellation data sets were obtained from each hospital. The authors then prospectively established root causes of cancellations by on-site investigation and interviews of the hospital personnel involved. The surgical department at the Norwegian hospital cancelled 14.58% of cases in 2003 and 16.07% in 2004. The American hospital cancelled 16.52% of all cases between May 1, 2003, and April 30, 2004. Administrative data may give a rough picture of causes of cancellations. However, most findings at either of the hospitals do not translate easily to the other.

Intestinal injury after thoracic aortic cross-clamping in the pig.

BACKGROUND: The mucosal surface epithelium is an essential part of the functional intestinal barrier, but its structural response to ischemia/reperfusion is only partly characterized. The purpose of this study was to provide a detailed morphological evaluation of intestinal surface epithelium after aortic cross-clamping. MATERIAL AND METHODS: Pigs were subjected to thoracic aortic cross-clamping for 60 min and subsequent reperfusion for 120 min. Tissue blood flow and high-energy phosphates were measured with microspheres and HPLC, respectively. Urinary excretion of (14)C polyethylene glycol (MW 4000 Da) (PEG-4000), loaded into an intestinal loop, provided an index of intestinal permeability. RESULTS: Jejunal blood flow was restored at 10 min after aortic declamping. Denudation of the basement membrane of the intestinal villi tips, as a consequence of epithelial shedding, increased markedly during the initial 60 min of reperfusion (P = 0.002). During the following 45 min, the denuded basement membrane was partly covered with low cuboidal and squamous-shaped cells extending lamellipodia over a wavy basement membrane. Restoration of ATP at 60 min after aortic declamping correlated inversely to the extent of denuded basement membrane (r = 0.75, P = 0.032). Permeability of PEG-4000 increased markedly after aortic declamping and was linearly correlated to the area of denuded basement membrane (r = 0.87, P = 0.01). CONCLUSIONS: Reperfusion for 2 h after aortic cross-clamping is associated with initial aggravation of ischemia-induced injury in the porcine jejunum, but thereafter with restitution of the surface epithelium. Restoration of ATP may be important to avoid intestinal injury after ischemia. Increased permeability of a macromolecule in response to reperfusion is closely correlated to injury of the surface epithelium.

Gut barrier dysfunction as detected by intestinal luminal microdialysis.

OBJECTIVE: To evaluate the use of gut luminal microdialysis as a tool for monitoring ischaemic metabolites, particularly glycerol, as markers of intestinal dysfunction during and after intestinal ischaemia. DESIGN: A randomised, controlled animal experiment. SETTING: National laboratory animal centre. INTERVENTIONS: In seven pigs the thoracic aorta was cross-clamped for 60 min followed by 2 h of reperfusion, while five pigs served as controls. MEASUREMENTS AND RESULTS: Glycerol, lactate and glucose in the intestinal lumen and mucosa were measured by microdialysis. Intestinal tissue blood flow was determined by means of colour-labelled microspheres. To assess intestinal permeability, (14)C-polyethylene glycol 4000 (PEG-4000) was instilled in a jejunal segment and then measured in venous blood. Intestinal blood flow was reduced to 10% of baseline by aortic cross-clamping ( p=0.001) and returned to baseline during reperfusion. Intestinal luminal lactate increased during ischaemia and further increased during reperfusion. The increase was paralleled by augmented intestinal permeability; there was a significant correlation between luminal lactate and venous PEG-4000 ( r=0.89, p<0.01). Aortic cross-clamping caused a marked increase in intestinal mucosal glycerol concentrations, which correlated with luminal glycerol during both ischaemia and reperfusion ( r=0.85, p<0.01). CONCLUSION: Microdialysis of lactate may be useful for monitoring intestinal ischaemia and reperfusion. Release of lactate into the intestinal lumen appears to be related to increased permeability. Intestinal luminal glycerol closely mirrored glycerol concentrations in the intestinal wall.