Comparison of preoperative versus postoperative transversus abdominis plane and rectus sheath block in patients undergoing minimally invasive colorectal surgery.

AIM: Ultrasound-guided transversus abdominis plane and rectus sheath block (TAPRSB) decreases pain scores and narcotic use postoperatively after colorectal surgery (CRS). It is unclear if the effectiveness of TAPRSB varies according to whether it is performed preoperatively or postoperatively. Our aim was to investigate this. METHOD: We compared patients who underwent preoperative TAPRSB or postoperative TAPRSB during minimally invasive CRS. Primary end-points were pain scores and oral morphine milligram equivalent (MME) use postoperatively. Secondary end-points included perioperative factors affecting pain scores and postoperative MME. Summary statistics and univariate analysis by nonparametric tests were utilized. The mixed-effect model was applied to model the repeatedly measured pain score. RESULTS: From April 2015 until May 2018 168 patients received TAPRSB before (115) or after (53) minimally invasive CRS. The cohort included 79 (47.0%) women, and had an average age of 59.11 (±12.32) years and mean body mass index of 28.32 (±5.82) kg/m2 . Indication for surgery was cancer in 66 (39.3%), polyp in 43 (25.6%) and diverticulitis in 43 (25.6%). Right colectomy was performed in 61 (36.3%), low anterior resection in 46 (27.4%) and sigmoid colectomy in 40 (23.8%) patients. The demographics of the groups were similar. Postoperative TAPRSB was only associated with lower pain scores at 12 h postoperatively. As secondary outcomes, average pain scores and MME were lower in patients who were older, had right colectomy or intracorporeal anastomosis. CONCLUSIONS: Postoperative TAPRSB resulted in lower pain scores than preoperative TAPRSB 12 h after minimally invasive CRS, but otherwise no differences were seen in pain scores or MME use.

Comparing depth from motion with depth from binocular disparity.

The accuracy of depth judgments that are based on binocular disparity or structure from motion (motion parallax and object rotation) was studied in 3 experiments. In Experiment 1, depth judgments were recorded for computer simulations of cones specified by binocular disparity, motion parallax, or stereokinesis. In Experiment 2, judgments were recorded for real cones in a structured environment, with depth information from binocular disparity, motion parallax, or object rotation about the y-axis. In both of these experiments, judgments from binocular disparity information were quite accurate, but judgments on the basis of geometrically equivalent or more robust motion information reflected poor recovery of quantitative depth information. A 3rd experiment demonstrated stereoscopic depth constancy for distances of 1 to 3 m using real objects in a well-illuminated, structured viewing environment in which monocular depth cues (e.g., shading) were minimized.