Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

Improvements in dynamic GPS positions using track averaging

The issue of improving a Global Positioning System (GPS), Precise Positioning System (PPS) solution under dynamic conditions through averaging is investigated. Static and dynamic data from the Precision Lightweight GPS receiver (PLGR) were used to analyze the error characteristics and design an averaging technique for dynamic conditions. It was found that the errors in PPS solutions are dominated by the satellite broadcast ephemeris parameters. The solution errors are highly correlated for a given set of satellites/ephemeris. The variation can be as low as 0.4 m in dynamic conditions, but a slowly changing "bias" of several meters is also present. For fitting the location of a road observed repeatedly with a PPS receiver a technique based on "space curves" was developed. Here the solutions are transformed from functions of time to functions of space (location). These then are used. Curves could be fit with a Bezier polynomial easily to the 0.4 m level. These analytic curves were then used to form an ensemble average. The bias vectors between the solutions were found with least squares estimation. These vectors were averaged using several techniques. This idea was applied to a short road segment. Using 9 independent measurements taken over 6 months, the road was surveyed at the submeter level

High Latitude Aspects of a Differntial GPS Aircraft Landing System

The use of differential Global Positioning System (DGPS) in an aircraft landing system at high latitude has been investigated. Both the effects of the high latitude on geometry and accuracy and the effects of scintillations on availability have been studied. Data was taken at McMurdo, and South Pole station, Antarctica over a two year period. It was found that commercially available systems should meet the FAA requirements for Special Category I landing systems in Antarctica.NISE-West/Vallej

Coordinates

Paper describing types of coordinates

Improvements in dynamic GPS positions using track averaging

This issue of improving a Global Positioning System (GPS), Precise Positioning System (PPS) solution under dynamic conditions through averaging is investigated. Static and Dynamic data from the Precision Lightweight GPS Receiver (PLGR) were used to analyze the error characteristics and design an averaging technique for dynamic conditions

High latitude aspects of a differential GPS aircraft landing system

The use of differential Global Positioning System (DGPS) in an aircraft landing system at high latitude has been investigated. Both the effects of the high latitude on geometry and accuracy and the effects of scintillations on availability have been studied. Data was taken at McMurdo, and South Pole station, Antarctica over a two year period. It was found that commercially available systems should meet the FAA requirements for Special Category I landing systems in Antarctica. (jg)http://archive.org/details/highlatitudeaspe00clynN

Precise Time and Time Interval Clocks, Time Frames and Frequency

In the Naval Postgraduate School course on Mapping, Charting, and Geodesy (OC 3902) an overview of precise time and time interval is given. This note is a summary of that material. Both the civilian and military world make heavy use of precision clocks and accurate time. Th