Association of intraoperative hypotension with acute kidney injury after elective noncardiac surgery.

BACKGROUND: Intraoperative hypotension (IOH) may be associated with postoperative acute kidney injury (AKI), but the duration of hypotension for triggering harm is unclear. The authors investigated the association between varying periods of IOH with mean arterial pressure (MAP) less than 55, less than 60, and less than 65 mmHg with AKI. METHODS: The authors conducted a retrospective cohort study of 5,127 patients undergoing noncardiac surgery (2009 to 2012) with invasive MAP monitoring and length of stay of 1 or more days. Exclusion criteria were preoperative MAP less than 65 mmHg, dialysis dependence, urologic surgery, and surgical duration less than 30 min. The primary exposure was IOH. The primary outcome was AKI (50% or 0.3 mg/dl increase in creatinine) during the first 2 postoperative days. Multivariable logistic regression was used to model the exposure-outcome relationship. RESULTS: AKI occurred in 324 (6.3%) patients and was associated with MAP less than 60 mmHg for 11 to 20 min and MAP less than 55 mmHg for more than 10 min in a graded fashion. The adjusted odds ratio of AKI for MAP less than 55 mmHg was 2.34 (1.35 to 4.05) for 11- to 20-min exposure and 3.53 (1.51 to 8.25) for more than 20 min. For MAP less than 60 mmHg, the adjusted odds ratio for AKI was 1.84 (1.11 to 3.06) for 11- to 20-min exposure. CONCLUSIONS: In this analysis, postoperative AKI is associated with sustained intraoperative periods of MAP less than 55 and less than 60 mmHg. This study provides an impetus for clinical trials to determine whether interventions that promptly treat IOH and are tailored to individual patient physiology could help reduce the risk of AKI.

Interpretation of digital radiographs by pediatric critical care physicians using Web-based bedside personal computers versus diagnostic workstations.

OBJECTIVE: To determine whether the interpretations of digital radiographs by pediatric critical care physicians displayed on the bedside personal computer differ from the interpretations of images displayed on the diagnostic workstation. DESIGN: Paired comparison. SETTING: A 38-bed pediatric critical care unit in a 372-bed pediatric university hospital. SUBJECTS: Four pediatric critical care fellows and four pediatric critical care staff physicians. INTERVENTIONS: Eight critical care physicians interpreted 114 radiographs in random order on two separate occasions. Each radiograph was assessed for the presence or absence of five chest abnormalities, the correct or incorrect endotracheal tube position, and the position of central venous catheters. These interpretations were scored against a gold standard. MEASUREMENTS AND MAIN RESULTS: Sensitivity and specificity were calculated for the presence or absence of five chest abnormalities and the identification of correct or incorrect endotracheal tube position. Kappa was calculated to assess agreement in the interpretation of central catheter position. Regarding chest abnormalities, improvement in sensitivity on the diagnostic workstation was statistically significant for one critical care fellow. The specificity on the diagnostic workstation was significantly worse for two critical care fellows and two critical care staff physicians. Regarding endotracheal tube position, improvement in sensitivity on the diagnostic workstation was statistically significant for one critical care staff physician. There were no statistically significant differences between the two viewing modalities for specificity measures. For central venous catheter position, there were no statistically significant differences in the interobserver or intra-observer agreements between the two viewing modalities. CONCLUSIONS: With the exception of diffuse chest abnormalities, pediatric critical care physicians can use the Web-based bedside personal computer for clinical decision-making with the confidence that the decisions will be similar to those made on the diagnostic workstation.

Interpreting three-dimensional structures from two-dimensional images: a web-based interactive 3D teaching model of surgical liver anatomy.

BACKGROUND: Given the increasing number of indications for liver surgery and the growing complexity of operations, many trainees in surgical, imaging and related subspecialties require a good working knowledge of the complex intrahepatic anatomy. Computed tomography (CT), the most commonly used liver imaging modality, enhances our understanding of liver anatomy, but comprises a two-dimensional (2D) representation of a complex 3D organ. It is challenging for trainees to acquire the necessary skills for converting these 2D images into 3D mental reconstructions because learning opportunities are limited and internal hepatic anatomy is complicated, asymmetrical and variable. We have created a website that uses interactive 3D models of the liver to assist trainees in understanding the complex spatial anatomy of the liver and to help them create a 3D mental interpretation of this anatomy when viewing CT scans. METHODS: Computed tomography scans were imported into DICOM imaging software (OsiriX) to obtain 3D surface renderings of the liver and its internal structures. Using these 3D renderings as a reference, 3D models of the liver surface and the intrahepatic structures, portal veins, hepatic veins, hepatic arteries and the biliary system were created using 3D modelling software (Cinema 4D). RESULTS: Using current best practices for creating multimedia tools, a unique, freely available, online learning resource has been developed, entitled Visual Interactive Resource for Teaching, Understanding And Learning Liver Anatomy (VIRTUAL Liver) (http://pie.med.utoronto.ca/VLiver). This website uses interactive 3D models to provide trainees with a constructive resource for learning common liver anatomy and liver segmentation, and facilitates the development of the skills required to mentally reconstruct a 3D version of this anatomy from 2D CT scans. DISCUSSION: Although the intended audience for VIRTUAL Liver consists of residents in various medical and surgical specialties, the website will also be useful for other health care professionals (i.e. radiologists, nurses, hepatologists, radiation oncologists, family doctors) and educators because it provides a comprehensive resource for teaching liver anatomy.